abray1

In a 350 bored 30 with the very best base and runners ported to there max like tpis or accel, slp etc. What is the highest usable rpm you can get out of a 355 SBC. If it was solid roller and had all the trimmings how much air would it support before it fell on its face like a stock one does at 4600RPM on a stock 350.
2nd question, Which base and runners works the best that is stock style not the fast tpi.

vetteoz

iTrader: (13)

Not going to help ; the long runners ( in any form ) are the restriction

This popular comparison shows the relative working rev ranges of the various SBC EFI intakes.
http://xtremecarzone.com.au/index.php?showtopic=386

Note that most LR setups are flat past 5K (compare the curves , not the Hp reading )
Observe the working rev range once a short runner or SP intake is used

MassD

iTrader: (1)

If you want any sort of real rpm out of the motor youre going to need a short runner style intake, like a 4150 style throttle body on a carb intake, or a stealth ram type design. Long runners are designed for low end power, you can rev the motor but it wont make any sort of horsepower.

abray1

You guys are mind readers. I have a stealth ram ready for a new 350 (very Mild) to go in my 92 Z vert. Since our cars are getting in the antique catagary I thought I might leave the stock tpi on it or find an accel slp or tpis stuff and have it ported for the look and have some performance.I would like it go to at least low 6000 RPM but if five is going to be the limit I guess I will go stealth ram. I already have it and have the good fuel regulator and the fittings for it so why not. You know in my opinion TPI is the best looking induction they ever made. It looks like something Darth Vador would use and destroy the universe with in his tie fighter.

vdoggie

yes to the last sentence!!

Thirdgen89GTA

iTrader: (5)

Cannot Argue with That!

efiguy

iTrader: (2)

Sorry but you are incorrect. The LONG runners aren't the issue, it's the SIZE of the runners. In other words the cross sectional area.
Look at an LS, they'll spin right up. But look at the runners, even the stock ones. They're already larger than the TPI stuff.

Your rpm will be limited by wherever the bottle neck is, intake, runners, or throttle body. Whatever is the most restrictive.

Orr89RocZ

iTrader: (20)

Agreed! The CSA of the port and runner tubes are way to small.

If you did port a base to the max without welding, and used a regular big tube shelf runner, you could spin to well over 6k with enough cam. Hp will peak by 5000 or so but cam big enough will hang on until 6k easily. Thats what restriction does, and eventually it may spike in hp like a second peak due to approaching a new harmonic wave length region.

If you weld the base to allow even more area in the port, and make even larger custom tube runners, you can pull closer to 7k. 1989gtatransam on this site peaks in the 6600 range and shifts by 7k

anesthes

iTrader: (12)

Runner length affects rpm range. Vizard, Bowling, Yunick, Wallace all have books detailing the physics behind proper intake manifold design.

Hogged out aftermarket bases are roughly 2 square inches. The total runner length of a TPI setup is: manifold 8” runners 11.25”, cylinder head 6” total 25.25”

What does a hot 350 with a XR288HR (for example) camshaft need to make decent power? Well peak torque should be around 3700-4000 RPM, and peak HP 6000-6200 RPM.

350 cubic inches, 288 degrees advertised, 4 harmonic waves comes out to about 2 square inch runner diameter, and 9.8" total runner length. A far cry from the 25" of a TPI setup.

An LS1 head has 5" of runner, and 10.5" in the manifold for a total of 15.5" TOTAL runner length. While slightly long compared to a HSR (12.26" TOTAL), or a victor jr (11.25" TOTAL), they are still quite short compared to a TPI.

You should consider changing your name to Accelguy, since you don't really know a lot about manifold/efi/engine design, and really not much about anything but Accel DFI. When the screen name is misleading, and your opinions are not backed up by fact or science we have a problem.



-- Joe

anesthes

iTrader: (12)

That's not exactly scientific evidence that his combo is superior and without fault. When he switches to a singleplane intake (which if I recall he was planning on doing shortly), he will probably pick up a half a second in the quarter.

My 355 hogged out and welded TPI pulled to 6,000 RPM with a 224 degree camshaft. Replacing it with a singleplane, it still pulled to 6,000 RPM. It just went 10mph faster in the quarter mile.

You are not getting your value our of your heads, compression ratio, camshaft profile, etc when your intake manifold has the wrong RPM range cast in.

-- Joe

jmd

iTrader: (4)

An L69 with a cam and headers that shifted nicely in the low 6000s with 4bbl is choked before 5000 with a TPI intake. A modified intake that still has loooooong runners isn't going to change that. Torque under the curve is still negatively affected by the mismatch of a cam and intake suitable for peak power at totally different ranges.

Either do a very slight cam that maximizes torque up to 5000, or ditch the intake and build something that truly matches and maximizes the combination.

Orr89RocZ

iTrader: (20)

You are missing the key aspect of different orders of harmonics found in the induction cycle. 4-5 harmonic waves happen over various lengths. Most i believe shoot for the 2 or 3 order harmonic wave as its usually the strongest and the lengths are reasonable to acheive in a car, but a 4 order length could also work which has much longer length

1989gtatransam intake was designed around a very specific and scientific process calculating the runner length for his specific combo. Everything matched and his numbers proved exactly that

NufNuffZ28

iTrader: (10)

I can't wait to install my single plane


In all reality, OP, you will be shifting at 6000 and that's only to fall back in the meat of usable power. My car with OVER 20 lbs on it I still shift around 6000

anesthes

iTrader: (12)

I understand the harmonic waves and powerbands. I started experimenting with different runner lengths over a decade ago. (look at my old threads). If you review my quoted post, you'll see I said "4 harmonic waves" (although I meant the 4th harmonic wave).


I was actually thinking of NufNuffZ28, not 1989gtatransam. However I did look up his combination regarding how he determined what runner length he needed.

In his own words: "However I used PipeMax and a friends EA Pro to determine the best intake tract sizes for my motor using 6500 rpm for peak horsepower and the 3rd harmonic. I used a set of SLP runners and mated them to the First Intake manifold. The only way to achieve the goal with what we had was to siamese the pairs of runners and using the remaining divider wall to "shorten" the runner length. "

So yes, he scientifically determined that to make the aftermarket TPI setup work, he had to shorten the runner length.

He doesn't say in his thread his final runner length, but if I do the calculations with his given 1.9 sq. in and third harmonic, I come up with 15.5" total runner length. Again, a far cry from 25" TPI.

He could have saved himself a lot of cutting/grinding if he just bolted on a different intake.

-- Joe

Orr89RocZ

iTrader: (20)

I was refering to his second design. He used 2" diameter tubing for runners and no siamesing. Runner length was around 20.25" and pulled well over 6500 rpm, peaks at around 6500. Very impressive. That was second order harmonics. I believe i have my orders mixed, 1-2 are longer than 3-4.

So it can be done. The whole brainwashed idea that long tube runners cant support rpm is incorrect. Shelf parts are simply not big enough in area to make it happen. If you fabbed a tpi that could fit under these cars with bigger runners, it would work fine over 5500 rpm depending on cubes. A 350 could easily rev out beyond 6500.

That said, other short runner intakes fit the bill both space wise and financially. To fab a big LTR setup like 1989gta's would be rather expensive

anesthes

iTrader: (12)

So he built a combo optimized for the the 2nd harmonic (20.25" runner to 7k) ? So he traded a wide power curve for a narrow peak. I don't know that you should be citing him as proof of accomplishment my friend. An 11" runner would have yielded him the same peak, but the curve would be flatter and wider.

It's not a 'brainwashed idea'. It's science.

Edit: I just realized this dude is from California - the TPI belt. I suspect his combination was built to comply with the smog ****'s.

-- Joe

Orr89RocZ

iTrader: (20)

Peaky curve? Thing made power everywhere

And the whole point of this thread is can a tpi ltr rev with usable power past the typical internet hype of 5000 rpm

The final and correct answer is yes a long runner can do it. There are ways to do it. Shelf products do not necessarily do it. If you cant understand it or believe it then I cant help you

This is for the die hard tpi guys. I wouldnt go thru the trouble of creating such beast as many other intakes are available like single planes and stealth ram types

anesthes

iTrader: (12)

No it didn't. It went up to 5500, then went back down, then hit the 2nd harmonic around 6200 and fell flat on it's face at 6600.

https://www.thirdgen.org/forums/atta...yno-run-36.jpg

And he did a great job of proving that he can make 413HP at 6500 RPM, instead of making 413HP at 5000 RPM like most aftermarket TPI setups on hot 350s. He took advantage of the 2nd harmonic wave and got a goofy dyno pull graph.


Trust me, I understand it. You are really impressed with that engine?

I don't know that their is many 'die hard TPI guys'. Their is a bunch of whackjobs in Socal who are restricted by the SMOG folks, and seem to have embraced those restrictions (stockholm syndrome?)



-- Joe

Orr89RocZ

iTrader: (20)

You have your opinion, i'll leave it at that lol

Dyno Don

iTrader: (7)

Don't forget it ran 11.57/116.xx @2500 DA and 3800#

anesthes

iTrader: (12)

Fair enough

-- Joe

Burnout91

Who are these whackjobs, Joe?

VincentZ28

iTrader: (2)

The car has all the interior in it. The driver weighs around 280lbs. Car and driver total weight is around 3900lbs. Oh yea and wait! On the dyno graph where goes down and go back up, that was the converter locking up. Here's one of the videos I took of the car on the dyno.

abray1

Anyone know of how much (approximately) it cost to do all that welding and siamezing and who does it?

Dyno Don

iTrader: (7)

The welding is around $100 Dr. J does the porting for $525
He is in So Cal

Dr. J's Performance