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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I'm hopeful of getting to a chassis dyno with my new setup. I know though I doubt I'll explore the part throttle side of things as dyno time is expensive and I'm looking for the WOT numbers so as to generate a decent profile for some further simulations. I might give a go at part throttle and 2500 RPM as that's where I spend most of highway time. That bit of info and working through the timing there (I've approached 50° advance with a very lean 16:1 cruise) would pay dividends on an extended (and planned) cross country tour. Just once. It does rattle there however but nothing was damaged during the last tear down. Not sure if the dyno operator would be obliging but they shouldn't care really.
That said, I'm in a transition where I think most of attention will be at the track and the street will only be occasionally. But I do like to drive. Fuel has just gotten so damned expensive that it kind of kills the hobby.
Fuel has gotten higher for sure, but I am still taking the 1987 G20 on Power Tour this year. Should not be too bad on fuel, with the Proflow 4 system on the mild L31 in it and cruising ~2,500 rpm @ 70. I debated throwing a spare 4L80E into it, but I have a good TH400 and 3.08s in it currently and swapping in the questionable condition used 4L80E would cost me more than any potential fuel savings would recover on that trip. I bet it will not get 5,000 miles a year on it after.
I am very happy with the overall combination. L31 with LT1 flat tops, a little head work on aftermarket vortecs, GM 6492 roller cam and 1.6 rockers. I have since swapped the single plane Proflow 4 manifold for a Mercruiser dual plane MPFI manifold, keeping the rest of the Proflow 4 system untouched. It runs very smoothly, pulls great vacuum and really sips on fuel compared to more cammed up combinations I have run. It runs smooth even at 1,000 rpm under load and the dual plane manifold has loads more off-idle and low speed torque than the single plane. I let it run without load on the driveline for a while since the TH400 and rear end had been sitting a couple of years. Wanted everything to come up to temperature and get re-lubricated adequately. Help the clutches get re-soaked with fluid, seals to heat cycle and hopefully soften back up a bit, etc. I have driven it around a bit, has good torque and moves along pretty nicely without really having to lay into the throttle hard at all. I have only been into the secondaries of the 4bbl throttle body and the TH400s detent downshift switch on the gas pedal a couple of times and it really wakes up when it is shifting about ~5,500. When I am not into the downshift switch it shifts about ~4,000 rpm at heavy part-throttle which is a great fuel saver. When the gas pedal starts to pickup the detent switch and the throttle linkage starts to pickup the secondary throttle plates, the pedal gets about 2x as stiff which is kind of nice actually.
I actually finished the ac rebuild recently. I need to update that thread in the cooling system area when I find time to. It is nice and cold now, cooling low 30s at the vent at idle on a 90F day. It goes to the muffler shop and alignment shop later this week. Then I plan to put a fair bit of mileage on it and finish up interior work before heading off in June for the week long Power Tour.
So, I had a few more emails back and forth with Mike Jones, and he really helped me crystalize the situation and my options, which I think should be helpful for others.
When I explained I was considering the 180s as an alternative to the 195's, he simply stated:
For peak HP at 5,500rpm and a 2,000 stall, go with the 180's.
For peak HP at 6,000rpm and a 2,600 stall, go with the 195's.
Then when I followed up, which I realize in retrospect I was sort of asking the same question, but I asked if changing my mind on head runner volume would change cams, and explained my plan to stay as cast for cost reasons, he responded with the following:
It's simple.
The 195's will make more power above 5,000rpm.
The 180's will make more power below 3,000rpm.
The correct option would be the AFR 180 Eliminator heads, but that's an additional $800. They have the flow capacity of the 195's, and the port velocity of the 180's.
If you don't have the money for the correct head, you have 2 choices. Give up some bottom-end, or give up some top-end.
I can make adjustments with the cam, to minimize the losses in either case, but you have to decide which way you want to go.
Thats really about all there is to the decision... I am trying to minimize cost, but I do recognize there are certain situations where forking out some extra funds just makes sense in the long run and I think this may be one of those situations, going with the 180 street cnc AFR heads. Higher runner velocities, but better overall flow than the 190 as cast! It's an extra ~$800, but I believe this option may allow me to get heads with both perimeter and center bolt cover mounting holes, which will allow me to keep using my factory valve covers, which while boring, will save me around $200, so that reduces the difference a bit, and I can always change them out later with ease.
So, I had a few more emails back and forth with Mike Jones, and he really helped me crystalize the situation and my options, which I think should be helpful for others.
When I explained I was considering the 180s as an alternative to the 195's, he simply stated:
For peak HP at 5,500rpm and a 2,000 stall, go with the 180's.
For peak HP at 6,000rpm and a 2,600 stall, go with the 195's.
Then when I followed up, which I realize in retrospect I was sort of asking the same question, but I asked if changing my mind on head runner volume would change cams, and explained my plan to stay as cast for cost reasons, he responded with the following:
It's simple.
The 195's will make more power above 5,000rpm.
The 180's will make more power below 3,000rpm.
The correct option would be the AFR 180 Eliminator heads, but that's an additional $800. They have the flow capacity of the 195's, and the port velocity of the 180's.
If you don't have the money for the correct head, you have 2 choices. Give up some bottom-end, or give up some top-end.
I can make adjustments with the cam, to minimize the losses in either case, but you have to decide which way you want to go.
Thats really about all there is to the decision... I am trying to minimize cost, but I do recognize there are certain situations where forking out some extra funds just makes sense in the long run and I think this may be one of those situations, going with the 180 street cnc AFR heads. Higher runner velocities, but better overall flow than the 190 as cast! It's an extra ~$800, but I believe this option may allow me to get heads with both perimeter and center bolt cover mounting holes, which will allow me to keep using my factory valve covers, which while boring, will save me around $200, so that reduces the difference a bit, and I can always change them out later with ease.
Every test I have seen and even my own results using larger port heads shows the exact opposite of what Mike claims. Under 3,000 rpm the larger port wins or is atleast equal in torque production every time. The 180 cc port might make a little more midrange but will give up power down low and up top compared to the larger 195cc port. Personal experience here as well, eventually the 350 bottom end will give you issues and nobody in their right mind stays at 350 cubic inches when they rebuild their short block in a performance application. The difference between a 180cc and 195cc or even 210cc runner is so miniscule in torque on a 350 it will not even be noticeable from the driver seat. Might as well get a bigger port head that will work even better on a 383 or 396 later.
AFR had a smog legal 190 or 195cc head at one point and tested it on a TBI 350 Suburban. The head had excellent torque and power gains on an essentially stock L05 350 in a Suburban and that was with the stock TBI manifold and TBI still on it. That engine was tested with a stock cam and 1.6 rocker upgrade.
Every test I have seen and even my own results using larger port heads shows the exact opposite of what Mike claims. Under 3,000 rpm the larger port wins or is at least equal in torque production every time. The 180 cc port might make a little more midrange but will give up power down low and up top compared to the larger 195cc port. Personal experience here as well, eventually the 350 bottom end will give you issues and nobody in their right mind stays at 350 cubic inches when they rebuild their short block in a performance application. The difference between a 180cc and 195cc or even 210cc runner is so miniscule in torque on a 350 it will not even be noticeable from the driver seat. Might as well get a bigger port head that will work even better on a 383 or 396 later.
Don't go throwing what I though was clear logic upside down!!! LOL!
I think the big thing that people may not be considering is the as cast vs CNC bit, it makes a huge difference to flow numbers, though velocities should be what they are for the given size, or even higher since you're getting more flow through the same length port...
I guess the question I ask you, would you get a 195 as cast AFR, or the 180 CNC'ed chamber and runners? (I guess the 185 CNC'ed could be a third option, but I haven't even tried to wrap my head around that one, lol!)
Feels like I may need to let the coupon lapse, and just wait till I get another one later in the year, many SCCA Chicago Region evens have those by the stack for the taking...
Don't go throwing what I though was clear logic upside down!!!
I guess the question I ask you, would you get a 195 as cast AFR, or the 180 CNC'ed chamber and runners? (I guess the 185 CNC'ed could be a third option, but I haven't even tried to wrap my head around that one, lol!)
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In as much as I appreciate Fast355's exhaustive testing, I'd be inclined to follow through on what the guy grinding my cam has to say.
Seems the 180 CNC is the way to go for a cake and eat it too point of view. That said, as Fast has pointed out, the differences between those and the as cast 195 might be difficult to detect. If I have a chance, I'll run an engine simulation using both with the cam Mike spec's.
My little 357 (yes, in a different world I would have gone 383) with the small heads (< 180 cc) but flow 255@.500" , along with 10.2:1, .040" quench and small tube headers (open) sims at 460 HP, 460 TQ. This is right in line with Mike's estimation. His design also takes into account the new stall converter I still don't have!.
Remember he's built countless 350's so I trust his experience.
Every test I have seen and even my own results using larger port heads shows the exact opposite of what Mike claims. Under 3,000 rpm the larger port wins or is atleast equal in torque production every time. The 180 cc port might make a little more midrange but will give up power down low and up top compared to the larger 195cc port.
Say what? You are quotings post talking stock GM castings. More at play there than intake port cc or flow. Different chamber designs, different sized chambers, big differences in exhaust port flow, spark plug locations and very fast burning swirl port vs non-swirl port intake ports. Also when I said the 163cc aluminun Vette head is efficient at lower engine speeds it is also because of the 58cc chamber vs the 64cc chamber of a Vortec. Compression helps build low-speed torque. The LS head comparison is the same, the 706/862s bump a 6.0Ls compression a full point compared to a 317 head. Compression trumps flow in low speed torque production. There was also a test done with the old LT-1 350. They built one with the early 70 model closed chamber heads that flow less and then swapped it to the 71+ open chambers, reducing the compression from 11:1 to 9:1 but increasing flow. The open chamber version lost a lot of torque but made more top-end power. Losing 2 points of compression cause a big loss in torque.
Yeah? I agree with you....about the compression part.
Originally Posted by Fast355
Also when I said the 163cc aluminun Vette head is efficient at lower engine speeds it is also because of the 58cc chamber
Originally Posted by Fast355
113s added torque is from compression and from port velocity. Those 163cc intake ports are efficient at lower engine speeds.
In ^that^ thread, I actually said that compression was the reason for more low end tq. I had told you to retest your claims, using the same compression ratio. ^That was your response to my statement; you emphasized the port size/velocity etc. -not just in that quote but throughout the thread. I don't actually care which heads do what...it's just weird what claims get applied to what, depending on the scenario.
...it's just weird what claims get applied to what, depending on the scenario.
I think it just goes to show that it's not a clearly defined thing. Is there a general trend? It would appear so. Look at what Mike Jones had to say about the two different heads and the effect of power output.
Then there's the testing done by others. Fast 355's myriad of tests have something to say about the trend not necessarily being evenly applied.
So, I guess it depends. There are too many variables in a cylinder head that would affect the outcome. Volume, shape, MSCA, gasket size, valve size, the relative efficiency between intake and exhaust, the valve job, et al, are all factors to consider.
I'm still of the mind that all else being more or less equal (if that's even possible) then for a given CFM, the smaller port is likely to impart a little more energy into the intake charge thereby helping VE and torque.
At least I'm hopeful that'll be the case. My current engine will be a reasonable comparison to the AFR 195 headed 350 that preceded it. But it won't really be apples to apples.
Might check warranties on the heads you're interested in. I see Brodix heads are listed as "race" heads and either have no warranty or a 30 day by the seller. AFR heads advertise lifetime warranty that I saw in a couple ads. With Chinese castings and who knows who machining a good warranty is critical with the dollars being spent I think. But any performance head with current design chambers and 64cc or so would be a good power adder.
I added the CNC Eliminator 180s to my chart and curves. The difference is really pretty staggering, improved flow across the board, while maintaining velocity. I think that has to be the right choice for me, now with my current plans, not the 383 bottom end I MAY upgrade to years in the future...
Only problem is the Eliminator heads will make me put the project on pause to save a few more bucks, hopefully a good deal presents itself some time throughout the summer and I'll pull the trigger then...
If you're going to upgrade at any point, the 180s are a waste. More cubes and/or more rpm, just get the afr cnc 195s for the exact same price (at least they were, idk about now) as the cnc 180s. If you're ruling out more power, the 180s are fine. Not that you can't ring out a bunch of power from the 180s, there's just way more to be had from the larger castings.
I doubt there's much you'll notice in low speed power loss on the street with the 195s. More slow speed power is lost in a cam, you make that up in gearing, in which case, WOT you won't be under 3000 rpm. And larger cubes can take advantage of more air. Long in the short is it's easy to get caught up in every detail and at the end may not make any noticeable difference to what you're doing with it because you won't really know without testing. It's so much more than cc and cfm.
If someone said they were putting 200cc heads on a small factory cammed 327 that idles at 500rpm, you'd think they were nuts. But that's pretty much what a stock 5.3 lsx is, seems to work just fine.
AFR’s 180cc "Street" heads are recommended for street, towing, or street/strip engines with displacements up to 383 cubic inches, operating up to 6000 RPM. AFR`s 195cc "Street" heads recommended for displacements up to 400 cubic inches, operating up to 6500 RPM.
It was once impressed upon me by more than one professional engine builder that you only want enough cylinder head to reach the performance goal.
If there are future plans, then so be it but planning for that will likely compromise the current build.
An important thing to note is that the cam will be spec'd for a given cylinder head and CID (among other things) so you design it around a package. Otherwise, there'll be further comprises and you're left with something that'll not perform as it should.
I've been there and done that. It gets expensive to make those changes down the road. If I were to do it again, I'd have left my original 350 with the RHS 170cc heads and small cam alone and built another engine altogether. Then I'm free to move up in displacement and get the proper parts to suit.
The only reason my AFR 195 headed LT1 lacks for torque is because I went with a yuge cam for 7000rpm peak power potential.
If I had put a more reasonable cam in there, say something in the 220° range, with a narrow LSA, or something more like a 225° with a wide LSA to keep the overlap down I'd have all the torque I could want at low engine speeds.
And honestly, by 3000rpm I'm making PLENTY of torque. I only lack torque below 2500rpm because of the overlap.
Ask yourself why then did GM put 200cc heads on the the LS1, a mere 346ci engine that in stock form makes peak power at 5600rpm?
Fun fact TPI nostalgia ignores. Both the LT1 and LS1 make more torque than the TPI L98 did below 3000rpm, while also making significantly more power than the TPI. The LT1 does it with a short-runner intake, while the LS1 does it with a medium length runner.
GM spent millions developing the LS series engines and yet they went with a 200cc intake runner for the LS1. The LS3 is 6.2L, so yeah, more displacement, but it's got a 260cc intake runner as cast.
If you talk to some of the old guys they will tell you that there is no way you should run a 260cc runner on something that isn't a monster 427 stroker that revs to 7000rpm.
Modern port design on good heads is EXTREMELY efficient. Even when stuck using the old SBC port layouts.
Buy the best head you can afford, bar NONE. More head, less cam to meet the goal.
The only reason my LT1 doesn't have set of a AFR 245cc heads is because I didn't shell out the money to have the block bored .030" or .060" over and if had gone with the larger head I'd have shrouded the valves and eliminated the flow gains from the larger head. So I went with CNC 195's.
Ask yourself why then did GM put 200cc heads on the the LS1, a mere 346ci engine that in stock form makes peak power at 5600rpm
GM spent millions developing the LS series engines and yet they went with a 200cc intake runner for the LS1. The LS3 is 6.2L, so yeah, more displacement, but it's got a 260cc intake runner as cast.
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You can't compare LS heads to gen 1. They're two totally different animals. This is what makes the LS such a potent engine. Similarly a cam spec'd for a 5.3 or 6.0 will be very different for a same sized Gen 1 with equally sized intake runners. But equally sized doesn't imply that they're equal.
Old school rules for old school engines. Now, if you want to talk about SBC development outside of the LS platform, look at the SB2. Way better heads by design. NA sees over 800 HP at 8000+ RPM on 358 cubes. But that too isn't a fair comparison.
By further to the OP, as was discussed earlier, whatever head he choses, the cam has to be spec'd with it in play if top results are to be expected. That applies to any engine.
Here's something to consider.
Looking at AFR's flow charts for their CNC'd 180 and 195 heads you'll see that at moderate valve lifts, .300" for example, that they're pretty much even. It can be seen that the larger intake valved 195 has a slight edge but...
Given very similar CFM, which port do you think will have a greater charge energy at those lower lift numbers? All else being equal, it looks to be that VE will be better with the smaller port at lower lifts as that greater energy promotes better cylinder filling. Mid-lift is where the valve spends more it's time rather than at full lift.
That said, for a given cylinder head, with that is a different engine spec altogether. Or at least it should be. RPM range, CID to feed and camshaft will/should all change with the different heads.
Pick a performance target and build towards that.
If it were me, I'd go with the smaller cylinder head.
Seeing as you intend to keep the revs below 6k, the benefit of the larger port isn't likely to be realized. I'd say your autocrossing would be better served with more torque rather than out and out HP. That's my thinking anyway.
In the cylinder head spec department, I've measured mine (as best I could) to determine port volume but just as importantly, the minimum cross sectional area. This is typically at the pushrod pinch (in a SBC anyway) although it could be at the valve seat throat. But it gives a good indication of air speed relative to CFM. The faster the air, up to a point, the more inertia it has to aid in cylinder filling. That's were the torque bump comes from as I understand it.
The valve job too has a significant impact on VE. Better and /or different profiles impact the flow at the seat in different ways. It's really difficult to do a valid comparison though as you'd need all of the heads in question tested on the same bench. In that case about all you could do is the old YouTube search for somebody like Eric Weingartner. He has a kajillion SBC heads tests with great data as a result.
This is why I'm keen to see what my little ports (~175-180 cc) and MCSA of 1.90 sq. in. will do for drag racing a 357 at 6000-6500. If my science is right I will have maximized the potential of that particular package which also includes small diameter headers at 1-5/8" and a dual plane intake with 750n CFM vacuum secondary carb.
Whatever you decide on for heads, if it's not the spec you provided to Jones Cams, get another recommendation. You could ask too that if you keep the revs to a certain point (and he could tell you what that point is) that you may be able to reuse your current lifters. That said, for the dollars involved it's cheap insurance with new lifters. Don't forget a valve spring recommendation. Mike and I discussed that and I went with his PAC 1218 suggestion.
Regarding your rear gear, as an example, I've a 700R4 that's been thoroughly modified. That includes your upgrades plus quite a bit more. Presently using a 10" TCI lockup converter. With my 3.73 rear gear and a 26" tire, 75 MPH sees 2500 RPM locked up in O.D. Seems like a highway cruising sweet spot. I've managed to tune it to 20+ MPG(US) in it's worn out and over-cammed version. I expect better with a fresher tighter engine and shorter cam.
As for the angled plug vs your header question, I can't say I'll be of any help there. I've got Hedman 1-5/8" long tube headers and other than needing more than one kind of tool for plug removal, (a 5/8" offset box end wrench is super handy in a couple of cases) the straight plugs have plenty of clearance. This included the plug boot to header gap as well. I've never had the need for a larger primary pipe other than a few seasons running the 350 out to 7000 on track days. I've dialed it back since then and the small pipes should be better suited.
This advice is spot on. Guys always pick too big of a head thinking it'll flow more so it'll add more hp. This is true on a given engine size but not true at all really. Without airspeed that CFM number wont be realised and without the right CSA you can forget airspeed. Theres a crazy test on Engine Masters somewhere that shows them using AFR heads on a 400+ ci, they picked a 165, a 195 and like a 210. While the 195 was the winner, the 165 was the wise choice for the street as average power was much better and Brule was all over it.
Id go with a 180cc max for a bolt on and run deal. As for the cam, you will need to re spec it for a different head if you do a custom grind. Mike is pretty good at cams and he will taylor it for what youre trying to do. It sounds like it needs to be street friendly with a lot of midrange to get you out of corners. I'd go for the Brodix 180 or AFR I guess. Profilers are awful nice too though and I think they are Eric W's. Fav. I think theyre Chads fav. too.
This advice is spot on. Guys always pick too big of a head thinking it'll flow more so it'll add more hp. This is true on a given engine size but not true at all really. Without airspeed that CFM number wont be realised and without the right CSA you can forget airspeed. Theres a crazy test on Engine Masters somewhere that shows them using AFR heads on a 400+ ci, they picked a 165, a 195 and like a 210. While the 195 was the winner, the 165 was the wise choice for the street as average power was much better and Brule was all over it.
Id go with a 180cc max for a bolt on and run deal. As for the cam, you will need to re spec it for a different head if you do a custom grind. Mike is pretty good at cams and he will taylor it for what youre trying to do. It sounds like it needs to be street friendly with a lot of midrange to get you out of corners. I'd go for the Brodix 180 or AFR I guess. Profilers are awful nice too though and I think they are Eric W's. Fav. I think theyre Chads fav. too.
180cc is too small for a strong running 350. I had heads that ranged from 170-185cc on my 305 builds and even they ran strong everywhere. GM used a ~190cc port on the LT4s from the factory.
A bunch of marine 350s and 377s had the GM 200cc Fastburn heads on them, a small 196/206 @ 0.050 cam and GM TBI on a dual plane manifold. They had a ton of low-midrange torque and only turned 5,300 rpm max. Malibu marinized some of the LT4s as well and put them into the Malibu Corvette. That boat would outrun a lot of 502 big block boats.
Put a better head on it and the cam does not have to be as large to make the same power. The smaller cam will boost low-midrange torque more than a smaller port head ever though about doing.
I will also add that a couple of years ago I worked on a ZZ5 in a heavy 2nd gen with a TH350 and a 2.73 gear. It was lacking low-midrange power and the owner was convinced it was the FastBurn heads costing him torque. Rather than buying heads and swapping them out, I convinced him to let me put a spreadbore dual plane intake on it with a well setup Q-Jet to replace the crappy GM single plane they shipped on the ZZ5 and 750 double pumper he had on it. Lets just say the head swap never happened because it was a completely different engine after. Even with those 200cc heads and not so great gearing it absolutely ripped from a stop.
This guy went from 163cc ZZ4 113 heads to old 190cc AFRs with a TPI combination. Wish he had pulled the engine lower, but the AFR 190s made more power trhoughout the recorded RPM range.
He then put a StealthRam on it.
https://www.eecis.udel.edu/~davis/z28/winter01/dyno/dyno021105/webpage021105.html
He did a lot of testing with that car back in the day. Some interesting data too from various combinations.
https://www.eecis.udel.edu/~davis/z28/winter01/dyno/
This guy went from 163cc ZZ4 113 heads to old 190cc AFRs with a TPI combination. Wish he had pulled the engine lower, but the AFR 190s made more power trhoughout the recorded RPM range.
I wouldn’t doubt that. The 113’s dont flow that well stock. Not anywhere near an AFR head. I like the smaller ports that flow well. Theres been a shift since the LS came out to use big ports/small cam because that’s how they get it done with less valve angle, but before all that mess it was common knowledge to use an intake port sized correctly for the application. FWIW, there’s A TON of guys running circle track with small port Vortec and other 180cc heads for a reason. It gets the midrange tq done and they make good power. These bad boys are still pulling some RPM too.
if the OP wants he can check the port sizes and velocity measurements using flow and see where he ends up.
Edit, youll still make power either way... But for 6k and under HP, smaller ports shine. If this was a 7000rpm+ deal... 200cc would be a no brainer.
Last edited by MrIROBZ; 04-07-2024 at 09:09 AM.
Reason: grammar
This guy went from 163cc ZZ4 113 heads to old 190cc AFRs with a TPI combination. Wish he had pulled the engine lower, but the AFR 190s made more power trhoughout the recorded RPM range.
By the way, good to see you still on here. TXTtopZ was my old handle, all the way back in 2010, before that I don’t remember what it was. You and I used to defend the 305’s against the 350 guys who were still reeling from not being top of the food chain anymore thanks to LS motors. The 305 is getting a lot of love these days!
You can't compare LS heads to gen 1. They're two totally different animals. This is what makes the LS such a potent engine. Similarly a cam spec'd for a 5.3 or 6.0 will be very different for a same sized Gen 1 with equally sized intake runners. But equally sized doesn't imply that they're equal.
Old school rules for old school engines. Now, if you want to talk about SBC development outside of the LS platform, look at the SB2. Way better heads by design. NA sees over 800 HP at 8000+ RPM on 358 cubes. But that too isn't a fair comparison.
By further to the OP, as was discussed earlier, whatever head he choses, the cam has to be spec'd with it in play if top results are to be expected. That applies to any engine.
Agree here too.
For anyone looking at LS for hint's on SBC performance, don't waste too much time. It's got a much straighter short side radius which pushes the TQ peak up another 1000-1500 RPM. That also allows smaller cams because the air doesnt have to navigate turns and lose velocity and momentum. Its a straight shot compared to the old 23 degree stuff. Might as well be an engine from another manufacturer when comparing the two. Its too bad theyre so ugly.
By the way, good to see you still on here. TXTtopZ was my old handle, all the way back in 2010, before that I don’t remember what it was. You and I used to defend the 305’s against the 350 guys who were still reeling from not being top of the food chain anymore thanks to LS motors. The 305 is getting a lot of love these days!
I do remember. My good friend David Kauffung and I still defend 305s. Always hated how Engine Masters got so political in their rules and disqualified his 305 the 2nd year after they decided to make an oil pan rule that took a lot of budget built stuff out of the competitions. They wanted more exotic aftermarket looking stuff in those competitions. His Fastburn headed 305 went from the 394 hp the first year to 468 hp the 2nd year with a more aggressive cam and more rocker ratio.
I wouldn’t doubt that. The 113’s dont flow that well stock. Not anywhere near an AFR head. I like the smaller ports that flow well. Theres been a shift since the LS came out to use big ports/small cam because that’s how they get it done with less valve angle, but before all that mess it was common knowledge to use an intake port sized correctly for the application. FWIW, there’s A TON of guys running circle track with small port Vortec and other 180cc heads for a reason. It gets the midrange tq done and they make good power. These bad boys are still pulling some RPM too.
if the OP wants he can check the port sizes and velocity measurements using flow and see where he ends up.
Edit, youll still make power either way... But for 6k and under HP, smaller ports shine. If this was a 7000rpm+ deal... 200cc would be a no brainer.
An inexpensive offshore 200cc aluminum casting with some slight sanding roll cleanup and a good valve job got it done for me on my L31 350 when the Mexican 062s on it cracked. I was less $ into the pair even with good valves, springs, and hardware than a single head in a 180cc offering would have cost. The 200cc heads flowed about 265 @ 0.600 and made more power everywhere than the iron Vortecs and allowed me to use 87 octane to make that power vs needing 91+. One would really be hard pressed to notice any difference in average torque between a 180cc and a 200cc port on a 350.
I will even go so far as to say David Kauffungs 305 had very strong torque even with the 200cc FastBurns on it, especially when he went away from the mild 112 LSA cam, (229@ 0.050) and ran something with a good bit more duration (242 @ 0.050) and tighter LSA for more overlap. Picked up his mid-range torque by a signifigant amount. He went from 394 hp to 468 hp with a cam and rocker change. Those 200cc Fastburns were working very well on his 305.
An inexpensive offshore 200cc aluminum casting with some slight sanding roll cleanup and a good valve job got it done for me on my L31 350 when the Mexican 062s on it cracked. I was less $ into the pair even with good valves, springs, and hardware than a single head in a 180cc offering would have cost. The 200cc heads flowed about 265 @ 0.600 and made more power everywhere than the iron Vortecs and allowed me to use 87 octane to make that power vs needing 91+. One would really be hard pressed to notice any difference in average torque between a 180cc and a 200cc port on a 350.
I will even go so far as to say David Kauffungs 305 had very strong torque even with the 200cc FastBurns on it, especially when he went away from the mild 112 LSA cam, (229@ 0.050) and ran something with a good bit more duration (242 @ 0.050) and tighter LSA for more overlap. Picked up his mid-range torque by a signifigant amount. He went from 394 hp to 468 hp with a cam and rocker change. Those 200cc Fastburns were working very well on his 305.
Its funny you mention that. David and I have been friends for a long time too. He's on my FB page still pushing the 305... I dig it.
From my understanding I look at street engines totally different than a EMC engine or even a drag/race type deal. Its not hard to get annoyed by a big cam, lots of RPM or sluggish response so I look at total package. What is happening at a stop light with the wife in the car? Is it going to annoy us? How is this thing going to drive just cruising to the local show or even out on a twisty road? For me, its about having my cake and eating it too. I want the car to be NICE. Idle nice, drive nice and feel responsive. I want to blow the tires off when I mat the pedal and fry them at a 30-45mph roll. I want the car to be fun and enjoyable because theres no way Im going to go out and win any roll races on the highway against anything modern with a blower, and around here in Central Texas there are some seriously fast cars. So I default to total package. I would hate to have a thirdgen SBC that has a big cam lope, big heads and drives like a typical big cam hot rod that just ends up losing anyway when ran against new stuff. To me there is no payoff in that situation. If I was to build a SBC to run with modern stuff, Id use a 4.125+ bore, a MR intake, a 240+ cam, probably a 3.825+ stroke, some 220-240cc heads and a power adder of some sort. These TPI 350's are a long way from that. So why embarrass myself?
Heres what the defines the correct head from the incorrect head. The PRP or pushrod pinch. This is the MCsA (minimum cross sectional area) that all flow speeds are created by and CFM is either made or restricted. You can see for a 350 aiming for 6000rpm, the PRP needs to 1.90 sq inches for 320fps. So then you ask yourself what does the MAX CSA need to be? Do you need a 200cc head which has a MUCH larger CSA to feed that small of an area? Your intake and head port sizes can't even match up using TPI or some of its variants without major porting and if you do that, youre trying to do what the guys 15 years ago did, which is make HP beyond 6000rpm.
From what I understand... 260-350fps is usually what average port airspeeds are in an intake port. If AFR says it flows 295cfm@.500" lift, that CFM number has an airspeed attached. If you don't have enough motor, or too big of an intake port, your airspeeds will fall and so will your cfm. Among that it makes it harder to tune, doesn't drive as nice, off idle response and TQ suffers. Will a 200cc head be horrible? No. Itll work. So would a 195... with room to grow if you wanted. But if youre trying to build something that wont be modified later... I would stick with the high velocity and smaller intake port of a 180cc head and enjoy the snappy throttle response and all the other benefits that go with it.
I'm just about spot on with that chart.
357. Cam spec'd to peak at 6200. Carry to 6500.
Heads flow 255 @ .500". MCSA is 1.9 in² (+/-). Runner volume started as an advertised 170cc. Minor bowl work to blend the valve job (not a stellar one though) so cc's might be 175 cc.
Some of my sims have shown this to be a tight package. That is to say, maximizing the heads so suit the CID and RPM. Jones did the cam and I spec'd more drag race that street with a 4000 stall convertor.
So far, just doing the first 50 miles of break-in, it responds like a champ with the old ignition and fuel tuning (all analog) from the overcammed and worn out 355 previous to this.
I'm just about spot on with that chart.
357. Cam spec'd to peak at 6200. Carry to 6500.
Heads flow 255 @ .500". MCSA is 1.9 in² (+/-). Runner volume started as an advertised 170cc. Minor bowl work to blend the valve job (not a stellar one though) so cc's might be 175 cc.
Some of my sims have shown this to be a tight package. That is to say, maximizing the heads so suit the CID and RPM. Jones did the cam and I spec'd more drag race that street with a 4000 stall convertor.
So far, just doing the first 50 miles of break-in, it responds like a champ with the old ignition and fuel tuning (all analog) from the overcammed and worn out 355 previous to this.
Thats perfect. Theres a guy on ST who I talk to regularly using 175cc heads on a 383 making 520hp and doing it at 7k. I don’t think I’m as big of a small port guy as he is but I default back to the dynos I’ve seen and my foxbody days where a set of GT40 and GT40ps used to make the car run 11’s and 12’s and absolutely annihilate tires! Very fun street cars!
Do you mind if I ask what Jones specd out for you? Just curious since it’s still a stock stroke deal with 175cc heads… or thereabouts…
Thats perfect. Theres a guy on ST who I talk to regularly using 175cc heads on a 383 making 520hp and doing it at 7k. I don’t think I’m as big of a small port guy as he is but I default back to the dynos I’ve seen and my foxbody days where a set of GT40 and GT40ps used to make the car run 11’s and 12’s and absolutely annihilate tires! Very fun street cars!
Yes. SpeedTalk has a litany of drag racers that race outside of the box. 406's with Vortecs. And quick too. Plenty of 383's although it was suggested that my heads on a 383 would probably be limited to peak HP RPM of 5700 give or take.
The heads I have just squeak the 357 into the RPM limit I was targeting. Then again, even with the heads, a different cam spec would push the RPM's further.
Of course not, but it might give us all (even the OP) a good idea on what custom grinders are up to. Has the OP even picked a cam?
Here you go. Most of the specs:
Pretty sure the OP contacted Jones however the head choice was still undecided IIRC.
357: 4.040” x 3.48” 10.24:1 Wiseco forged 5 cc piston Eagle SIR rods 5.7” GM forged crank Balanced .008” deck 750 Barry Grant VS RPM Air Gap RHS Pro Torker Vortec heads. 175cc, 254@.500 Jones Cam: 280°/284° @ .006", 232°/236° @.050", 108° LSA, 104° ICL .360"/.360" Lobe Lift .576"/.576" Valve Lift 1.6 rocker ratio 4.100" x .032" head gasket Headers: 1 5/8” x mid length, 3" collector
Following the theme of port volume a little further, as we've discussed here, it's not volume per se that is the measuring stick to be used. It's all of the other measurements that make one head work better than another.
Eric Weingartner did this video about a year back. The explanation, or most of it, is in there.
Following the theme of port volume a little further, as we've discussed here, it's not volume per se that is the measuring stick to be used. It's all of the other measurements that make one head work better than another.
Eric Weingartner did this video about a year back. The explanation, or most of it, is in there.
Yeppers! Thats a good video and he explains why the big ports should be used and when not to use them. Ive watched it a few times. FYI - I spoke with Chad Speier on my lunch break about this (which coincidentally is close to the same thing im doing, just with iron) and he recommended the average CSA be no more than 2.0-2.1 for a 1.90" MCSA. If that doesn't tell the OP which head he should choose, nothing will. Just looking at the airspeed and cfm requirements he gave me that ought to tell you all you need to know. 383+ go 195 or maybe 200 ish... depending on RPM and head... 350/355 Stay 180-185 or even less. I also spoke to Charlie earlier kicking around some ideas for the TPI build... He also agrees on this. So you have a few guys who do this for a living all saying the same thing. I dont know what else to say...
I just noticed AFR makes an L98 optioned cylinder head using the 180cc heads. That right there is what I would get if I wasnt trying to be sneaky on my stuff. Looking at the port sizes on the AFR heads, you have 2.050x1.250" for a csa of 2.56 without the corners subtracted... so probably 2.5.... maybe less. Keep in mind runners on a TPI system have a CSA of 2.08 with big tubes... So your cross section goes from small to big which is why I started with a smaller head for TPI. If I was running a Super Ram or HSR, I would open up the heads CSA to something like an AFR.
Wow, that was a lot to read and digest. Not sure if it was lost through the thread, but I am running a holley stealth ram, I'll have to look up the port dimensions and calculate csa. (Cross sectional area, right?) I did get a suggested Jones cam but that was for the as cast afr 195. It 8s pasted earlier in this thread.
Two things to point out, it seems there are two very different camps on the topic, and the way posts have been going back and forth, its nearly making my head spin, lol!
I feel like a big missing part of this discussion though, is the port and chamber condition, people keep throwing volumes around, but looking at the cnc afr 180, it flows more at nearly every lift than the as cast 195, but obviously with much better velocity.
I think my current thought is that ill save up for a few months to get the 180 cnc afr eliminators. They flow better than the as cast 195, as stated, and it makes sense to me about throttle response, and velocity, so i think im joining that camp. Plus afr advertises that head for up to 6k rpm, which i dont plan to exceed, and up to 383 ci. I think once i do redo my bottom end i may just go 355, but even if I went 383, I could. I will have to reach back out to Jones to get an updated cam suggestion, but I'm not sure how much it will change, considering my goals are the same, and the two heads flow about the same amount...
First things first now though, I just pulled my camaro out of storage, and need to change my tc lockup settings cause I'm over heating my trans... below 50 mph...
Welcome back.. Im going to tell you right now that if you are planning going 383 and have an HSR, 195's will do fine. HSR intake ports are straighter and dont have the 180 degree turn going into a dogleg intake base and then the transition into the head issue. This means you dont have to shrink the port to keep the air going. IF youre staying 350/355, 180's for sure.
Your HSR intake ports are probably still smaller than a AFR 195 head, but porting them would fix that. FYI, you could also get the 180's and port them later. Theres definitely some guys who will work some magic on that head and get better results than AFR which will be more custom tailored to you application. That being said, don't be afraid of a 195 for this given your goals.
HSR is my favorite aftermarket intake btw. It makes more TQ than the MR for the street which is what I like.. But if I were you, I would build the 350 then start saving for a Dart SHP 4.125" bore deal... Port the HSR and then step up to a Profiler V2.50 or something. Ever heard a 420+ cube SBC scream at 7,000rpm?+ Its better than coffee in the morning, ill tell you that. lol
From a casual observation, without all of the math details, it would appear that the Stealth Ram and the 180 CNC AFR eliminators would be a decent fit on a 350.
Not sure if I had said it here or in another thread, but if I had yet another engine planned, I wouldn't revise/retrofit the one I have as I've typically done in the past. I'd keep the current assembled and strong running engine intact and build something new from the ground up. (I like the idea of a 4.125" bore too).
It is a big hit up front in expenses but to have a complete spare does pay dividends down the road. Or at least it did for me the one time I did a wholesale change with this current chassis. In my case, I sold off the spare to offset some of the costs after the new engine was proven performer.
At 350ish ci, "lower" rpm range, I don't know if you'd see any difference. My disclaimer to that statement is that you never know without testing. I went with 180s and a HSR, port match is nearly identical with both parts being untouched
I'll repeat this. Again, if not you're going to upgrade, the 180s are a good match. This is a picture of the port match of the same parts(180 eliminators, HSR), untouched. But if you decide for more power the 195 eliminators are the EXACT same price. The 180s would be a waste. There are lots of people with mild-ish cams and larger heads. It works, maybe not optimum, but still plenty good. Decide your end goal before deciding your part choices. You'll spend more time building than driving if you don't have an end goal. Or just leave it alone and drive it. Projects sometimes just end up perpetual projects whether you like that or not. Your car looks nice, it'd be a shame if it sat on jack stands for years at a time.
Last edited by aliceempire; 04-09-2024 at 12:46 PM.
I'll repeat this. Again, if not you're going to upgrade, the 180s are a good match. This is a picture of the port match of the same parts, untouched. But if you decide for more power the 195 eliminators are the EXACT same price. The 180s would be a waste. There are lots of people with mild-ish cams and larger heads. It works, maybe not optimum, but still plenty good. Decide your end goal before deciding your part choices. You'll spend more time building than driving if you don't have an end goal. Or just leave it alone and drive it. Projects sometimes just end up perpetual projects whether you like that or not. Your car looks nice, it'd be a shame if it sat on jack stands for years at a time.
I agree with you and your logic and looking at the potential end goal. I've been exactly in this spot. That said, I did learn something along the way. Initially, I built towards a well suited package. Heads, cam, intake, carb sizing were all developed to compliment each other. The mistake I made was in the quest to go faster. What I did was the usual hot rodding approach and took it apart which at various stages left me exactly where you describe. Up on stands and not being driven. What I should have done was leave the first engine intact, enjoy it and build the next big thing off on the side. At the end of the day, I'd have two engines both of which were designed as a unit.
I suppose in the end what I'm saying is, build a well sorted engine and leave the prospect of the "what if" for another project altogether. My thinking is reinforced by the fact that I'm still stuck with a 350 and small heads because I kept picking at it. I could easily have a 406 built and the 350 with the money I've spent on one engine alone.
I agree with you and your logic and looking at the potential end goal. I've been exactly in this spot. That said, I did learn something along the way. Initially, I built towards a well suited package. Heads, cam, intake, carb sizing were all developed to compliment each other. The mistake I made was in the quest to go faster. What I did was the usual hot rodding approach and took it apart which at various stages left me exactly where you describe. Up on stands and not being driven. What I should have done was leave the first engine intact, enjoy it and build the next big thing off on the side. At the end of the day, I'd have two engines both of which were designed as a unit.
I suppose in the end what I'm saying is, build a well sorted engine and leave the prospect of the "what if" for another project altogether. My thinking is reinforced by the fact that I'm still stuck with a 350 and small heads because I kept picking at it. I could easily have a 406 built and the 350 with the money I've spent on one engine alone.
Solid advice! Not only that but its better to do your r&d, build it and then put it in the car. It saves the car from getting beat up by constantly rearranging stuff and tools smacking around it... Leaning on the fenders... Nose etc.
03-31-2024, 04:39 PM
