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Re: Headers and exhaust options for 700 hp street car
Probably a good guideline but cfm is highly dependent on gas temp. EGT will vary on tune and fuel type slightly, and on pipe material as it moves thru the system. Different grades of steel will shed different amounts of heat so egt will vary downstream
exhaust length tuning is also dependent on gas temp. Pipemax has an egt value
Re: Headers and exhaust options for 700 hp street car
Originally Posted by BadSS
I've never used PipeMax - verify it, but I suspect that it's giving inside diameter of the pipe. Most 18 gauge 1.75" headers (advertised outside diameter) have an inside diameter of 1.65". 18 gauge 1.875" headers will have an inside diameter of 1.775".
I’ve been sizing exhaust systems around Vizard’s “Zero Loss” formula for many years without disappointment. He established (dyno testing – flywheel HP - straight pipes) that you need approximately 2.2 CFM of flow per HP at 20.3" to not see any reduction in power..
PipeMax uses O.D. based on an .065" wall thickness. I will double check that when I'm back at my PC.
Following Vizard you are also aware that his "zero loss" system, which I'm very familiar with, also consists of exhaust termination boxes (or box as on the 2000 something 700 HP Corvette he describes in several of his books).
You are NOT going to get open header output without those boxes. Something has to trigger the pressure wave which what's needed to simulate open headers. Without it, all you have is a high capacity exhaust with zero tuning qualities. Not that there's anything wrong with that. But for the purposes of this discussion, this is the highest output option for a 700 HP 3rd gen Camaro.
This is why, considering that it's all but impossible to put a termination box on a 3rd gen (although I DO have a plan of sorts), cutouts are the closest thing you'll get to open headers. In actuality, cutouts ARE open headers.
Re: Headers and exhaust options for 700 hp street car
Keep in mind this is on nitrous. While a somewhat small shot, nitrous motors seem to behave differently. Im not sure exhaust wave tuning is as prevalent on nitrous motors as it is on na. Id be curious to see, im sure some on something like this. The heavy nitrous guys just want to get the exhaust out as fast and efficiently as possible.
off the bottle this would apply more. I havent seen anyone really pull off the termination box idea on a thirdgen. The typical header collector lengths for best result usually is 15-18” and thats right at the trans subframe with no room. Next best would be double length so 30-36”. Then 60-72”. Those may be more doable. But weaker signal. Nevermind trying to get all the primary tubes correct length
Re: Headers and exhaust options for 700 hp street car
I understand the nitrous side of things. And yes, it would seem bigger is better. Then again, if the OP had built a dedicated N20 engine, with a cam spec to suit, I probably wouldn't be replying as my experience with nitrous is a ways back when street racing had less of a stigma. And the science then wasn't what it is today.
As for termination boxes, I've posted too that it's all but impossible on a 3rd gen. That said, I've calculated that an oval 4" pipe about 36" long would serve as a sufficient size to get the job done. It would have to be incorporated like the Vette picture posted earlier. Both collectors entering a single chamber. Then whatever you want out the backside. 4" would work well. There may or may not be room alongside the torque arm and driveshaft though.
But, I don't believe that's an objective here.
Sufficient capacity certainly is.
The addition of cutouts would definitely be a game changer with respect to output though. I'll go out on a limb and say 10% improvement over even the best exhaust. The results from others seem to indicate that.
Regarding the primary pipe lengths, it's been put forward that there is an upside to having different lengths and that's that the "power band" is spread out some. Then again you can see that a given pipe length operates over a range of RPM. So there's plenty of room for overlapping lengths. That is if you subscribe to that particular theory.
Re: Headers and exhaust options for 700 hp street car
I am fairly confident that I do NOT have the real-estate under the car to do a true dual exhaust, and I really also don't have the desire to make that work just to have a "dual system". Can not do dumps or side-exit either, because this is a street car. A big diameter single exhaust is my most likely choice.
FWIW my $159 5.3L LM7 with 220,000 miles makes 750bhp (520-620rwhp most days) through a $40 single exhaust system composed of ~3" Pipe salvaged from diesel trucks at U-Pull-it.
It is a daily driver with focus on reliability, cleanliness, simplicity (single exhaust is very simple)
The key to ignoring all the BS/$$ involved with exhaust size, placement, tuning & efficiency is turbocharging. It can also eliminate the need for nitrous.
A turbo also improves engine RPM capability thanks to exhaust cushion which protect rod end caps, allowing higher RPM and less wear and tear.
I used a resonator and muffler to bring the noise level down to OEM sound. People standing behind the car thinks it still has a stock engine, the 2.4L 4 cylinder.
Quiet, simple, reliable, turbocharging improves everything, highly recommend you get familiar with it, as it allows us to skip all the tiny nickles and dimes details regarding length/tuning/cam/etc... and just focus on turning a boost dial up until you see the power you want.
Re: Headers and exhaust options for 700 hp street car
Some pics so you don't need to dig through massive build thread
This is the 3" exhaust composed of random stainless tube salvaged from various sources. Some of it was literally scrap on the floor of my friend's shop.
You want Thick walled as possible through the entire system to conserve heat energy which reflects in the exhaust gas velocity. It is ideal to dump the exhaust once it reaches approx 200-300*F because the low heat energy causes it to begin to condense, swirl (turbulence) which will hinder exhaust flow. If the system is built using the proper thick-walled exhaust tube, the exit temp at the tailpipe will be near 250*F~ or so. The muffler should boil water pretty much, thats how you know its hot enough for 'good' performance. I put a $37 cutout on it to mess around but it really isn't needed at just 500-600rwhp.
Use All V-bands on the exhaust system for easy access. I can disconnect my entire system with basically 3 V-band clamps and have the engine out quickly.
Position the turbo and exhaust with plug access priority. I can reach all 8 plugs and change them in 30 minutes- this is a necessity for performance cars.
The key to longevity, oil control, clean engine, is a fully factory PCV system like found on Toyota Supra / Nissan Skyline,
with short as possible hoses between compressor inlet and crankcase. A 1.5" Hg pressure drop post filter drives WOT pcv, using the turbo like a scavenging pump.
This is how all factory turbo cars are setup. This eliminates the intake manifold oil related issues (blow by being pushed into the intake manifold) because boost slams the PCV valve shut tightly at WOT.
Sorry to interject here I just wish you will see how easily done and the simplicity of turbocharging for reliability. I recommend aim for longevity with each component i.e. Low lift camshaft, slow ramp opening rate for valves, maintain low engine RPM redline, stock unmodified bottom end, high quality air filter, full PCV system, and the engine will last like stock 200k 300k miles or whatever, leak free. Then provided you have the right fuel system (I used $99 in tank fuel pump and 5/16" Hard lines support 600rwhp) just turn up the boost until target power goal. Once you wish to pass 600rwhp into the 800rwhp range there are several important details to reconsider but for just 500-600rwhp it is very simple setup and affordable.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by BadSS
I’ve been sizing exhaust systems around Vizard’s “Zero Loss” formula for many years without disappointment. He established (dyno testing – flywheel HP - straight pipes) that you need approximately 2.2 CFM of flow per HP at 20.3" to not see any reduction in power.
Here is a portion of the the article that everybody always talks about.
The 2.2 cfm/Hp is actually just one point in a curve with 2.2 approaching asymptotic (black curve). There is a range where the losses are not that big of a deal for the sake of easier packaging. This curve was developed with a particular engine not even close to 700 Hp and I highly question whether it is scalable to higher output engines. If I'm down as much as this curve says then I need to strap on some duals and go blow away the n/a dyno record at my local speed shop. But I can guarantee I don't have enough engine to do that so my 3.5" single is doing better than this curve suggests.
Unfortunately I couldn't keep tires from spinning on the rollers so I never got good comparison with and without the mid-pipe. The run without mid-pipe it was obvious the engine was making a lot more torque at low rpm but tires spun at 400 lb-ft just like all my runs that day. I've thought about going back after fixing the bind in my torque arm but it's not worth the money for just a number.
Re: Headers and exhaust options for 700 hp street car
I am really digging this in-depth discussion. Keep it rolling fellas.
Also, glad that BadSS chimed in and Kingtalon, two very knowledgeable people and great advice.
it is good to know WHY the thicker tube-walls are preferred too.. and that it will benefit overall heat conductivity out o fhte tailpipe. I had not thought of that. The 4"mufflex system is indeed described as heavy and thick-walled, even by Denny at Mufflex.
I spoke to him on the phone today and will be heading down there to pickup the system on Friday of this week. He reccomended a 4"-to4" y-pipe from a company called coan, (or cone, or cohn) who is based out of california. I'll ask him for more details when i get there since I didnt have luck finding it during a quick google search. i did find that flowmaster scavenger pipe that BadSS mentioned, it looks to be about 17" long. Here is a link to it: https://www.holley.com/products/exha...MaAh1dEALw_wcB
I am DEFINITELY going to be doing V-band clamps as much as possible on this system. With the ways I use the car and the times I will need to remove the exhaust, it just makes sense. I will have to find soem good quality ones, but Vbands will be used where they can be fit in.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by QwkTrip
Here is a portion of the the article that everybody always talks about.
For me, here's the key takeaway from that article. This is what I alluded to earlier.
To build a no-loss muffled, high performance/race system, it is vital we work with the two key exhaust system factors in total isolation from each other. The first of these factors is the pressure-wave tuning from our length/diameter selection, and the second is minimizing backpressure by selecting cats and mufflers with suitable flow capacity for the power concerned.
What's being said here is despite what you might try and achieve with pipes and mufflers, at best you'll have free flowing exhaust (which again is what you want to achieve on one level) but you'll never get to the zero loss output plateau (or very nearly so) without some sort of open air chamber.
That said, there is one interesting approach. However, due to the packaging, it's not entirely fit-able under a third gen. That would be to work with the values calculated with a suitable software program (or trial and error like in the old days...does anyone remember painting the collector extensions?) and once a length has been established, somewhere along the 2nd order harmonics (~50" for the OP's car) you hang the right kind of muffler there. A glasspack style muffler would compliment the length of pipe for the overall dimension whereas a Flowmaster muffler would hang off of that 50" as it represents the open air reflective quality we're looking for.
Something you can fit on a vehicle with sufficient ride height but very difficult in a lowered 3rd gen. That would be known as dumps before the axle. Sort of like my old 68 Beaumont (Chevelle). Plenty of room there. Problem was I didn't know the science when that car was active.
One option I explored with the Camaro when I was at the chassis shop regularly was to cut out the rear seat pockets and flatten the floor in that area. Then the mufflers tuck up in there. A kind of thanks but no thanks for me.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
I am really digging this in-depth discussion. Keep it rolling fellas!
Do you envision a y-pipe similar to this?
This was much nicer when new. That's 2 1/2" stainless made out of a bunch of J-Y bends. The same could be replicated in 3".
Personally, I'd skip stainless altogether and go for a thermal coating. (Which I believe is your plan?)
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
I will have to find soem good quality ones, but Vbands will be used where they can be fit in.
You'll want one side of the y pipe to be slip fit so you can make adjustments for final fit when you throw it up in place. That's the way my stainless works is and it never goes in exactly the same way twice, that slip fit is really important
Re: Headers and exhaust options for 700 hp street car
There are two kinds of generic v-bands to be aware of
One with out a lip, and one with a centering lip which makes the joint extremely rigid. Pay attn to which and where you use these different styles.
The centering lip is very important for exhaust near the engine, because it prevents leaks. Use them close to the engine as possible to help ensure leak free joints.
The issue with centering lip is that it forces the exhaust into some exact position, and holds it there rigidly. This can make the joint difficult to connect over time especially if parts of the system warps or moves for whatever reason. When the system begins warming up and expanding this can create stress if no other part of the system can respond with flexibility.
The same goes for when the engine torques (moves) position, the exhaust needs some kind of rubber mount system between it and the vehicle or it will stress and eventually crack because engines do not sit still, therefore I suppose that an exhaust system cannot be held rigidly to anything other than the engine itself to which it is bolted and only for some distance as materials begin to flex and warp and torque due to the overall length of the system makes highly concentrated stress more possible the further we get from the engine (more torque for larger distance between engine and the part of the exhaust system you are investigating for stress).
Thus, There should be a flexible pipe section between any two centering style V-band clamps to prevent stress due to movement between them.
As we go further back the in the exhaust system cooling down say 700*F 600*F 500*F ranges there may be a second V-band, for example the flange in my first picture. That position of clamp can/should be be non-centering for a couple of reasons. First, it will make connecting and dropping the exhaust system much easier. The Centering style v-bands tend to glue together and separate suddenly with a different range of stresses on the system depending how long its been and go together equally as rigidly, it needs to be some perfect matching angle. If the goal is speedy access, you will appreciate the non-centering style of V-band in these type of locations for quick attachment, and possible slight misalignment. Second, it allows the flange to move subtlety overtime into a lower energy position (least stress) for the system. If its been properly lubricated , the V-band using anti-seize and kept it clean by shielding it from debris, the lubricated flange may gradually drift due to the stresses imposed on the system and over time it will settle and become comfortable in the best position for low stress in the system while fully warmed up and vibrated by driving. If positioned properly, the V-band is very speedy and quick to access the 1 nut so you can come back couple days after installing the system and lightly tap the V-band flange while re-tightening it a little bit and inspect behavior and positioning when they are new.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by QwkTrip
Your 3-in single is really quiet compared to what you're about to get into. Anything you do to make the exhaust system naturally support a lot of horsepower is going to result in the exhaust system being very loud. My 3.5-in single has caused me hearing damage.
The way around that is large dual pipes with S-tube mufflers. Basically the exhaust system is so big that the restrictive mufflers aren't actually a restriction for your setup. But we don't have the real estate for that under our cars.
So that leads back to the cutouts. It pretty much always leads back to cut outs because we don't have the real estate for better things.
If you want duals then you could retrofit a 4th Gen dual exhaust into your third gen. At least the hard part of the bends over the axle will be done for you. Texas Speed, Kooks, Speed Engineering all have dual 3-in for the 4th gen. And they're all loud as heck... I mean super freaking loud.
The other way around the noise issue is 100 lb of sound dampening in the interior. You make the noise, but less of it gets to you.
The conversation always starts out with which exhaust system makes the most power and eventually ends with damn my car is too loud. You don't have a race car, you have a street car that makes a lot of power and you want to be able to enjoy driving it. Your ears can only take so much and that has to be considered.
Re: Headers and exhaust options for 700 hp street car
Engine Masters hosted by David Freiburger at the WestTech Dyno has some great videos on exhaust sizing and mufflers backed up by Dyno runs. A lot of myths blown out of the water. If you haven't seen the series definitely worth watching. Engine Masters is hosted on Amazon Prime and on YouTube.
Here's a link for the 2.5" vs 3" exhaust;
Re: Headers and exhaust options for 700 hp street car
A lot of myths blown out of the water...
The problem with a number of the Engine Master's videos is that they aren't very scientific.
If you tell me that smashing a primary tube on a header until it's almost flat won't make any difference in power output, I'll say BS.
Some of them I enjoy. Others are flawed.
Re: Headers and exhaust options for 700 hp street car
I don't know what the "right" answer is. When I had the thirdgen with the 412" sbc, and the t-trim supercharger I was running the 1 3/4" stainless headers with 3" single aerochamber dual out after a big flowmaster Y collector around the tail shaft of the trans. I knew the headers were good for the power, but the 3" single exhaust was suspect. I went through a lot of ideas in my head, I really wanted to either do a dual 2.5" over axle or side pipes. It's just very tough with the thirdgen chassis to do big exhaust and be able to use it on the street. In comparison, my C4 has a huge tunnel area and enough room over the IRS to run dual 3" if I wanted to. (I don't, it's only a 450hp car).
Interestingly enough, my convertible has side exhaust and it's bigger than my high-hp thirdgen was. 1 7/8" long tube headers, and big side pipes. (not even sure the diameter, but bigger than 3" by far). I have two sets of these in fact. I bet they could support 800+ hp easily, and believe it or not they are not as loud as one would think.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by anesthes
I know one thing for sure, that generation of Corvette with those side pipes is still one of my favourites iconic cars.
I remember very vividly the look and the sound of whatever sportscar class they raced in, bombing around Mosport Park when I was much younger. I got to drive a couple of them back in the day. A 350/350 4 speed and another big block version. No "Lake Pipes" though.
I'd buy one today if it didn't take my entire retirement fund portfolio.
(Is that an American Racing wheel?)
Re: Headers and exhaust options for 700 hp street car
Originally Posted by skinny z
I know one thing for sure, that generation of Corvette with those side pipes is still one of my favourites iconic cars.
I remember very vividly the look and the sound of whatever sportscar class they raced in, bombing around Mosport Park when I was much younger. I got to drive a couple of them back in the day. A 350/350 4 speed and another big block version. No "Lake Pipes" though.
I'd buy one today if it didn't take my entire retirement fund portfolio.
(Is that an American Racing wheel?)
The side pipe exhaust has a very distinct tone. It's interesting. My favorite sounding exhaust is a dual 2.5" with flowmaster 40's. Not a high horsepower exhaust but a good sound.
They are getting expensive, like everything else. Driver condition cars are having no problem fetching 35-40k. Show quality is just insanely priced. But then again, I was looking at new pickup trucks and to replace my Sierra it will be around $75k..
The wheels are US mags, new in September (with new tires). truthfully I don't like the way they look, and put them on the facebook marketplace with the tires. Going to go back to a stock 15" wheel.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
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Headers should be arriving on Thursday
Be sure to post the specs of those headers. It'll be interesting to know how they stack up against the PipeMax recommendations.
Primary lengths, shortest to longest.
Primary diameter and wall thickness.
Collector length in this case is somewhat irrelevant as you'll be extending them anyway. They'll become part of the y -pipe you're building. You may also want to check where the merge might be as it would roughly correspond to where a crossover is ideally located.
Re: Headers and exhaust options for 700 hp street car
Yeah, I didn’t see the note in the printout about all pipes being outside diameter. I had input his data into the Engine Analyzer - it recommended an optimal size of 1.662” and it’s based on inside diameter. Figured it was probably inside on the PipeMax as well since the numbers were so close. However, I’m not completely surprised PipeMax, or any other simulation, would recommend what amounts to a 1 5/8” “street header”. Sometimes extenuating factors of “the real world” can seem to contradict a simulation’s recommendation. This is when there’s no substitute for actual testing.
I’ve installed and swapped out a number of headers on 450-600HP, 383-406 street/strip engines back in the day. Most were running full dual exhausts or at least turndowns. I have never, repeat never, seen a time where off the shelf 1 3/4” headers didn’t pick up a 450HP or greater SBC over 1 5/8” off the shelf headers.
It’s possible that a lower RPM torquey 530HP engine might produce more power with a set of custom length 1 5/8” dyno headers where the flange doesn’t overlap the port and the primary has a long straight length before making the bend down. However, most off the shelf 1 5/8” headers overlap the ports on performance heads and have a right bend right off the header flange whether it’s needed or not. Plus you’re more or less stuck with the lengths available unless you want to modify them at the collector area. Heck even off-the-shelf 1 3/4” headers can overlap some performance head’s port, especially when ported. I think that’s why I’ve never seen a 1 5/8” header out perform a 1 3/4” header in anything I’ve dealt with. I suspect others would see similar results.
Yes, I’m familiar with a terminator box - a buddy welded up one for me and I’m running it on my 2009 G8 GT. It replaced 3 of 5 factory mufflers on the car and made a significant difference in throttle response. In the event anyone is interested here’s a link to where I posted about it on the G8 forum. https://www.g8board.com › threadsMid-Mufflers Delete - 36” Long Terminator Box | Pontiac G8 Forum
It takes a lot more work than most people would be willing to do to fit a terminator box, or boxes, under many cars. While I will always run one when I can, I’ve come within 0.14-seconds of uncapped with tuned torque tube (about the same or better than just uncapping) compared to a relatively straight 3” dual exhaust system with turndowns before the rear axle on my G-body car. I later swapped to a dual 3.5” exhaust due to the amount of nitrous I was running and while it only dropped a little less than a tenth without the nitrous, if you do the math, it put me within about 0.05-seconds of uncapped with the 3” torque tubes.
Anyway, for what it’s worth, if I had kept my IROC, I would by hook or crook fit a good set of 1.75” long tubes and get a 3” dual exhaust system under the car.
If that couldn’t happen then I’d run dual 3” pipes for as long as I could, use that big FlowMaster Y into the 4” pipe, and fit the biggest straight through 4” muffler I could fit in the stock location. Unless the OP plans on more HP and/or nitrous this should work nicely.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by BadSS
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I was a little surprised as well to see a street header with a 1 5/8" primary considering that's it's a fairly big motor in an old school way ( thinking now you can buy a 572 or 632 BBC over the counter (632! really?)). Then again that 1 5/8" has a full exhaust hanging off of it so somewhere in the analysis it's suggested to keep the pipe sizes down. Is that a velocity thing? I can't say.
But, looking at a race only header, which you have to admit, full exhaust or not, any racer is going to go for it even it means that it'll produce less output when combined with the rest of the package (so says the analysis). That race header is 1-3/4" I.D. (more or less) so it falls in line with what you've observed in the racing world. No argument there.
I'll say that anyone that's has experimented with, let alone has had success with termination boxes (TB's), is OK in my books. At the very least it demonstrates an appreciation of the science and I applaud you for the effort and results. Wish I could do the same in the Camaro.
Getting the right exhaust system, whether dual 3" or a single 4" I'll say is key. Not that it's going to yield open header results as would the TB's (or nearly so) but it's part of the plan if you want to be competitive.
Which brings us around to strategically placed cutouts. I think there's room for them, even with the subframe and trans crossmember getting in the way. Flick a switch and BAM! There's your open header results.
That's my plan ultimately. We'll see where the OP goes with it.
Re: Headers and exhaust options for 700 hp street car
Cutout is def the most fun thing on my car. Absolutely use it every day, every time I Drive anywhere, its like a magic switch and it serves so many different uses you would be surprised. Its really really good when the exhaust is OEM silent when the cutout is closed, though. Because you can hide a crazy combo under the hood....
Re: Headers and exhaust options for 700 hp street car
If that couldn’t happen then I’d run dual 3” pipes for as long as I could, use that big FlowMaster Y into the 4” pipe, and fit the biggest straight through 4” muffler I could fit in the stock location. Unless the OP plans on more HP and/or nitrous this should work nicely.
thats a good combo, seen it work well. Nice merge.
on my last turbo car i did dual 3” off the turbos into sections of 3.5” into a Y pipe with 5” outlet. Diesel exhaust all way back. It was 70 lbs and gigantic, sounded awesome. And fit surprisingly well. But dont know if it did anything for the combo or not
Re: Headers and exhaust options for 700 hp street car
Originally Posted by BadSS
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If that couldn’t happen then I’d run dual 3” pipes for as long as I could, use that big FlowMaster Y into the 4” pipe, and fit the biggest straight through 4” muffler I could fit in the stock location. Unless the OP plans on more HP and/or nitrous this should work nicely.
Originally Posted by Orr89RocZ
thats a good combo, seen it work well. Nice merge.
on my last turbo car i did dual 3” off the turbos into sections of 3.5” into a Y pipe with 5” outlet. Diesel exhaust all way back. It was 70 lbs and gigantic, sounded awesome. And fit surprisingly well. But dont know if it did anything for the combo or not
What muffler would you run with that?
Biggest 4" sounds ear splitting. At least for everyday driving. At the track, not so much.
Re: Headers and exhaust options for 700 hp street car
Best 4” stuff i found were the dynomax ultraflo rounds. They had two versions a 6” round case and a 9” round case i think it was at that time. Def much quieter than a bullet. But still loud on a high compression engine.
probably would try a bullet upstream in driveshaft tunnel area then a big ultraflow in stock location.
other better idea is 4” down the tunnel then split into dual tips out back along the frame rails, use ultraflo round 3” mufflers with 6” case. They fit but its tight
I also like the Dynomax ultraflo mufflers. They do make a 4” inlet that’s 6” round and 22” long so that might be a good choice especially at $112.
The bigger the case size the better the noise suppression so in this case (pun intended) I’d fit as large as you can wherever you end up placing the muffler(s).
That said, Orr knows what he’s talking about and what works on these 3rd gens, so going with anything he suggests should make you happy.
Re: Headers and exhaust options for 700 hp street car
awesome stuff recently written on here. I have been busy so I will catch up on all this tomorrow and reply accordingly.
But I did get the headers and drove down to mufflex today and grabbed the 4" setup... will take pics tomorrow and type up a good update.
Hoping to have some of the parts installed by end of the weekend so that I can discuss the proper way to design this "middle section" of the exhaust system.
Re: Headers and exhaust options for 700 hp street car
I'm actually really surprised somebody makes a 3" dual for our cars now. First time I've ever seen this. Stupid expensive but maybe other companies will follow suit.
Re: Headers and exhaust options for 700 hp street car
Stupid expensive is right!
Plus you have to have their headers. Good for the LS swap guys but not so much for the Gen 1 crowd.
The duals do look nice though. Curious to know what they use for mufflers
Re: Headers and exhaust options for 700 hp street car
I recall having a conversation with Matt (mw66nova) of Walter Racecraft and he described how the 3" Speed Engineering duals for a 4th gen will fit our cars with little to no modification. There has to some fiddling with the head pipes as it would have to fit any number of header brands but it looks to be that the bulk of the work is done.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by skinny z
Good for the LS swap guys but not so much for the Gen 1 crowd.
Engine doesn't matter, if you have long tubes then exhaust is going down the tunnel. That's why it would be handy if there are more third gen kits out there.
Fourth gen starts to look the same after the x/y pipe but everything forward of that needs to be trashed and remade for third gen. Hanger locations will need to be relocated for third gen too.
Re: Headers and exhaust options for 700 hp street car
Yeah. There's always going to be some cobbling together of the head pipes.
You're right that it would be nice if we a little variety.
I've some flexibility there though as my y-pipe is three pieces. I could toss the Magnaflow 2 into 1 merge and build an X-version.
Saturday morning musings...
Re: Headers and exhaust options for 700 hp street car
holy smokes Qwk, that is crazy expensive for that 3" dual system! whewww!
I'll probably scroll up to the top of the page and read/respond later, but i wanted to put out some info of my progress, so that I could run my ideas for the "middle area" past you fells... so sorry If I didn't get to reply to some of the recent posts.
I broke the exhaust system down into thirds, so I knew how I was going to handle each segment.
1st third: Headers only (ebay stainless steel kit)
2nd third: header collectors, cutouts, and 3"-4" merge pipe (to be determined)
3rd third: main pipe, over axle pipe, muffler, and tailpipe (mufflex 4" system with magnaflow muffler)
My headers arrived in the mail on Thursday. the box was beat up, but fortunately all of the pipes inside the box were in good shape. I bought this $212 ebay kit knowing full well that I would not be using the 2.5" collector pipes or the 2.5"into3" merge Ypipe. After discussion with you fellas here, I determined it would be perfectly ok to cut-off the necked-down 2.5" diameter section of the header collector and leave it at 3" diameter. The flanges are not warped at all and are thick, The welding on the inside of the primary pipes is pretty decent too surprisingly. There is 1 bung/port for an oxygen sensor, but I had planned on welding in my own instead so this port will stay capped closed.
Yesterday, despite the morning snow storm, I drove down to Mufflex in Trenton, NJ and purchased their single 4" system. I decided ont he straight through design of the magnaflow muffler, taking into account everything you guys said in these past two thread pages. I'm sure some of you had the same reaction to seeing a 4" diameter exhaust, and man this pipe diameter is big! It is an aluminized system, with the stainless steel magnaflow muffler. It came with a bunch of band-clamps, hangers, and hardware. I spent a good amount of time chatting with Denny at mufflex and he gave me a heads up that this exhaust might cause my AFR to lean out a bit; so I should beware that I might have to add some fuel into my fuel tables. Good to know! Any of you guys have similar experience with a free flowing exhaust making the afr lean out a little bit? He also recommended some other things, but nothing we haven't already covered.
Got everything unpacked this morning and laid it out in the driveway, putting my old exhaust system next to it. I measured the lengths of the primary header pipes on both the new ebay headers as well as the old DynoDon's headers. I started drawing out what my middle section might be comprised of, based on our discussions above and some photos that others have posted on previous threads here on TGO. I knew that it really would be better for my visualization if I bolted stuff on the car, so after lunch I started bolting stuff on (see next post).
Below are just a few photos showing the similarities/differences of the dynodons vs the ebay headers.
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Last edited by IROCZman15; 01-08-2022 at 08:59 PM.
Re: Headers and exhaust options for 700 hp street car
...continued
flanges/ports:
Inside Ebay collector:
Inside DynoDons collector
Magnaflow muffler:
I got everything picked up off the driveway and brought the new components into the garage, where I turned on the heat and put on some tunes. I cut off the necked-down section of the header's collectors and I will true up the cut before I weld a V-band onto it. Then, I started with the passenger side header, and I predicted it would be easy, but I did not expect it to be that freakin easy. I probably didn't need to even take out the spark plugs, plug wires, or undo the other wiring, but I do think that I would have needed to remove the starter...which i had already done. This header slipped right in like a dream. I was laughing in astonishment as it was happening! Then I went to the drivers side, where I had also already removed the plugs and wires, oil pressure sensor, as well as the Walter-racecraft steering shaft. It went right in just as easy as the passenger side! The only cursing I was doing in my garage was to the tune of "holy s***, I can't f****** believe this is going this easy! Underneath, I was elated to find out that these headers truly do not hang all that low and at the bottom of them, they are still about 1" above the bottom of the oil pan. I only installed them with 3 header bolts per side, but they are snugged up and I used the old gaskets for now...knowing that I will be taking them out for welding. Oh, and the protective covering on them is Glad peel-n-stick kitchen wrap, just to prevent my hands or tools from scuffing them up. I will be putting a T-fitting for my oil pressure sending unit,and I am going to be adding a secondary oil pressure gauge to the car, up on the A-pillar in February. As for the oem steel transmission fluid lines, I have always fought with those and I am done. I am going to buy a few linear feet of 5/16" copper-nickel tubing and some fittings so that I can route the lines in a less obtrusive manner under the car. I will also be getting some DEI heat shielding to slip over the trans cooler lines too.
I had the headers in so quick that I just kept on moving and decided to mock-up the mufflex system too. I wanted to see where the "front" of the main pipe would be so that I could start to figure out the middle #2 section. The mufflex pipes are very big but I was super impressed by the fitment and placement of the bends. Looking under the car before installing them, I said, man this wont work. But once I put em in, I was like wow, this is niiiice. .
So that leads me to the complex project of what to do in the middle. I absorbed everyone's input as well as other technical research I did across the internet, and I am hoping I can pull off my plan here. I am fully aware that this will require me either building a new transmission mount/crossmember and also notching out some portions of the oem frame to create pockets, and I am ok with doing that. I also will need to cut and redo parts of the S&W crossmember that holds the torque arm and doubles as a driveshaft safety loop. However, if I can do that properly, I think I can have a long 3" collector off of each header pipe and then bring this to a 3" y pipe with a cutout on each side. These dual 3" y-pipes can then join into a 4" flowmaster Y (part number Y300400) which can then meet up with the mufflex system. I did a rough 2-Dimensional sketch of this on cardboard.
Anyone have any thoughts on why this would NOT be a good idea, or if it is genuinely a pretty good way of building things, I would liek to start ordering some parts tomorrow night. I would need a second DMH cutout, along with its corresponding Y-pipe ($199 total). The flowmaster 3"-4" Y pipe is like $60. I am considering some of that fiberglass heat-wrap on this whole Y-pipe section. I am fully aware that heat wrapping it can trap moisture and rust the pipes, but it might be beneficial to keep the heat inside the exhaust pipes instead of radiating out of the pipe's exterior and baking the transmission, underside of the cabin, and nearby lines/electronics. Thoughts? If I do decide on some heat wrapping, it might make sense for me to use some sections of my old hooker 3" exhaust system to use for straights, curves, and pie cuts when building each collector. I already have the pipes and it would save some money on buying new sections of 3" tubes to cutup and weld together.
So, that is where I am at for now. Got wayy more done today than i had planned on, so thats good.
Last edited by IROCZman15; 01-08-2022 at 09:11 PM.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
As for the oem steel transmission fluid lines, I have always fought with those and I am done. I am going to buy a few linear feet of 5/16" copper-nickel tubing and some fittings so that I can route the lines in a less obtrusive manner under the car. .
That was always a PITA for me too.
Then I adapted an AN fitting to the transmission and have a 12" length of braided steel flex hanging off. I swung those up onto the frame rail in front of the firewall and adapted to steel tube up to the cooler.
You wouldn't necessarily have to go to the frame rail. You could adapt to your existing metal lines along the engine ( if that's what you have) at a convenient spot.
Makes that part of a transmission removal pretty slick.
The -6 AN to 5/16ths steel tube adapters can be seen in the bottom left. Also required is the trans case cooler fitting to -6 AN.
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Before I sold the IROC and was looking at running dual 3", I was looking at buying a couple of these and possibly cutting and extending the center oval section and/or putting in the bent oval tubing if/where needed. I never got any deeper than just an initial look under the car before I got an offer for it that I couldn't refuse.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by obeymybird
Zman not sure how much you will gain from the cut outs. I mean this setup is going to breath pretty free as is.
It's not a gain really. It's that the engine will have a reduced output if the exhaust scavenging isn't exploited.
About a 10% recovery is the kind of result reported from some back to back tests.
For 50 HP, I'd give it a go. It's about trying to reproduce the output the engine made when it was dyno'd in the builder's shop with open headers.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by skinny z
It's not a gain really. It's that the engine will have a reduced output if the exhaust scavenging isn't exploited.
There may be more scavenging when exhaust is flowing undisturbed for greater lengths of a system than when it is cut short, as the still-hot exhaust is leaving the system before it can perform flow work on the exhaust valve
I've seen it in turbo cars, 2L engines with open downpipes vs the well designed Greddy style systems 3.15" full length exhaust,
the full length has been noted to improve spool character and increase top end breathing ability (higher compressor wheel speed, reduced exhaust gas pressure), which is strange since its usually one or the other
Re: Headers and exhaust options for 700 hp street car
Originally Posted by Orr89RocZ
Id be willing to bet the turbine dampens exhaust pressure wave pulse and may be much less effective at scavenging as in a na deal.
Exactly. Just think if the turbo application can take advantage of a full length system, what such a system could do for an NA engine. That was kinda my point.
Although it may have more to do with exhaust gas velocity and flow work than individual pulse tuning.
Both gas velocity AND harmonic play a role in scavenging and pressure drop signal presented at the ends of a tube where there is some flow.
It surprised me because I used to think that all turbos would prefer a drop in backpressure over any kind of lengthy system- but no. There is definitely a spool and subtle onset of increased torque with a cutout partially closed on my system for example (I tried with 2L and 5.3L same results), and less tire spin because the slight restriction keeps boost from suddenly increasing as fast as well. There is probably a bonus to pressure drop at the turbine because of exhaust gas velocity is good and pressure is lower due to low mass flow rate- remember that 400 500 600lb-ft of torque at 3200rpm where a good street turbo spools is only a few hundred horsepower or whatever worth of flow say 35lb/min, so it does well inside a limited, low flow pipe which isn't good for peak horsepower at just 35lb/min but supports incredible street midrange torque. And actually it says something for cutouts which open after a certain boost or RPM point trigger, where additional flow rate is required beyond some point, taking advantage of both low diameter and then large diameter systems. And this is exactly what the 1995-2002 Toyota 2jz-gte twin sequential turbo does, it uses 1 turbo exhaust at first and then brings the next online at some point using actuator in the exhaust, a 'cutout' except the cutout leads to another turbo.
Closed system ideal for starting from a dead stop- open system seems ideal when already highway rolling.
And it seems like the right exhaust length/design can enhance both.
IMO the harmonics are really important for headers, header length and size, collector volume. The Exhaust gas flow within individual tubes from each cylinder. The same way a TPI engine harmonics play a role- individual tubes with a collective plenum volume sort of thing. The effect is called 'water hammer' in the fluid mechanics book, and there is some great pictures of the pressure wave dispersion or disparity or whatever, it shows the low and high points, explains how it happens, and there is some math showing how it relates to a periodic function. I spent many hours trying to memorize exactly what it means but its not easy to understand from conceptualization of molecules point of view like I normally do things.
Once the exhaust hits the 'plenum' of the system the acoustics are supposed to bounce back towards the engine at that point. SO anything or any length of exhaust system downstream to that I would think will interact with the collector more than the engine in terms of downstream harmonics.
The exhaust gas velocity on the other hand- hot moving fluids can do work in the tube, even from great distance. Think siphoning energy. This is where I would concentrate my efforts if I had to run an exhaust system some great length, and especially if it was going to be changing size or shape at any point. You don't want to transition the size of an exhaust or intake pipe unless you have to, it tends to obliterate the tuning AND velocity, creates turbulence or pressure changes that have big picture impacts. It depends where we are talking also, like after an intercooler upsizing the intercooler pipe is fine becuase the intercooler is a giant turbulence factory and everything coming out of it needs to reorganize anyways.
And something else to be aware of. The speed of sound in a fluid is dependent on temperature. Any harmonic/helmholtz tuning calculations therefore must be done with some temperature in mind. Then, the system will function optimally near those temperatures, but it's character will wander as temp deviates. And exhaust tends to cool rapidly as it leaves a cylinder- there can be a large difference "differential" in the exhaust temp. Which is another reason why thermal barriers are so important- coatings, wrap, shields, blankets, etc...
Re: Headers and exhaust options for 700 hp street car
Had a busy day working on everything aside from the car, so no updates; I also have to order parts in order to proceed.
Skinny: yup, I thought about going with some -AN adapters and a flexible trans lines, but I'm really digging the copper nickle stuff. My whole brake system uses copper nickle, and all my hard-lines on the nitrous system are also copper nickle. Super freakin easy to work with, so i might just make a set of copper nickle transmission fluid hard-lines and route them somewhat similar to how you did it. The steel lines were always in the wrong spot at the wrong time, and they don't budge, so I am tired of that.
BadSS: Wow, that round-oval-round pipe is super awesome. I expected it to cost WAY more than that price. If I decide to skip the cutouts, that might be the pipe I need (one each side) to get me past the trans-mount area. Awesome. thanks for sharing that. Also, I had never heard that phrase "by hook or by crook" until you mentioned it last week, and I found myself saying it just yesterday right as I was preparing to put in the fit header. I was like " well, I gotta make these fit, by hook or by crook!" and now its in my head!
obeymyburd: that my other train of thought.. do i really "need" the cutouts, or is it more of just a "bonus" to this already very free flowing exhaust system? Still trying to determine that. Not having to buy another cutout would save me a good $200, and I could probably sell the existing 3" cutout for a gain of about $100. But, will I leave any noticeable performance aspects hindered or un-attained? Thats what I can't decide upon just yet. and that brings me to what skinny and Kingtalon were posting just next..
...about keeping hot flowing exhaust pulses in BOTH of the pipes for a longer distance instead of having them BOTH belch right out after passing the tailshaft...leaving the rest of the 4" system very "unfilled" with any hot exhaust gasses at all really.
And that photo of the long dual pipes under that car, I actually have that photo that I printed out after taking a screenshot of it. It has been a photo i have looked at many times, and as his work with the pipemax program showed, this would be a great setup. However, With my S&W subframe kit, there is no way i could pull that off. The S&W kit has extra "outrigger" bars that go from the subframe connector bars over to the outside door rockers (I put my floor jack on these when lifting the car from the side). I was going to post a link to the S&W kit, but it looks like they drastically changed the kit that I have had in the car for the past 12 years. No photos came up of my setup during a quick google search, so I will take some "under car" shots soon to show you guys.
So, tomorrow night I will read what you guys suggest and take some more measurements under the car. If the decision to do cutouts is a resounding "yes" then I will buy another cutout and prepare myself for the extra work involved in that aspect of the project. However, if I (and we) come to the conclusion that It makes more sense to simply run the car with no cutouts for a year or so, then I can plan the project that way. There is nothing saying I can't add them in later, but on the other hand, if I am already in the trans tunnel cutting and modifying stuff, it would be sensible to do it all at one time. On the other hand, by saving the money on not buying a cutout, I could put that saved money towards having the home-built section of the collectors/y-pipe thermally coated instead of using the fiberglass heat wrapping and metal zip-ties.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
. I spent a good amount of time chatting with Denny at mufflex and he gave me a heads up that this exhaust might cause my AFR to lean out a bit; so I should beware that I might have to add some fuel into my fuel tables. Good to know! Any of you guys have similar experience with a free flowing exhaust making the afr lean out a little bit? He also recommended some other things, but nothing we haven't already covered.
This is how I discovered how restrictive the spintech single in, dual outlet muffler really was. I had to add a significant amount of fuel to the tune above 5500 when I put the straight through muffler on. You could noticeably feel the power lay over. I'd keep a close eye on afr's after you get it together and probably go ahead and ramp in some more fuel in the upper rpm range before you take it out.
Re: Headers and exhaust options for 700 hp street car
Regardless of what exhaust you end up with, you’ll be doing the final fine tuning in car so expect some adjustments over any engine dyno tune etc. i havent seen any major change in afr on exhausts but the changes i have made werent that significant i guess. I seen cutouts make 15-20 whp changes on some mild combos but fueling was not noticeable different so idk. It would have to be very restrictive to cause issues imo.
A full exhaust system headers to catback on a stock ls1 car i had ran ok without any tuning and with tuning picked up 12 whp. exhaust itself added a good amount over stock but changes in fuel and timing only made 12 on that car. Your mileage will vary lol
01-04-2022, 06:39 AM
