if your heads are changed then it has to be your intake sumwhere or injectors wat injectors u runnin again???

Ok, the results are in.....

The dyno session produced a whopping 373 HP & 410 TQ to the rear wheels.

Kevin91z also laid down 364 HP & 386 TQ

It just proves TPI can make power when you fix the intake system to flow some air.

Those numbers are better than mine.

Fellow TPI'rs,

I hope that this string is still going. I've had an 86 IROC sitting in my driveway for years. After a few failed attemps to sell it, I've decided to restore it. It will be all original with the exception of the motor and trans. The trans is complete, I have Marsh pulleys, L 98 aluminum heads (not ported), edlebrock headers, and a few other go-fast parts from TPIS. My question is what intake should I be going with to achieve 350-375 HP while it remains street driveable. The fols at TPIS said it will never happen with a TPI because of the long tube runners. XBased on what I have read, here's what I was hoping to do:

Runners - AS&M seem to be the best compared to EDBK, SLP - including the siamese runners, (plus they make TPIS).

Throttle Body - Mixed reviews on this. Should I port out my stock 48 mm to 52 or is that at all necessary. DOn't really see why I should pay 300 bones for a new one.

Plenum - Keep stock unit just port match to large tube runners

Intake - Looks like edlebrock makes the best hi-flow out there (also make s the one for TPIS)

Please give me some feedback on what I'm trying to do, but more importantly, what you have done successfully and unsuccessfully to your cars.

Thread jacking is considered rude. Good luck with your project and try the search button

what's thread jacking?

"to achieve 350-375 HP"

For clarification is this flywheel horsepower?

It is when you join a thread with 6 pages of post discussing a member’s ride, and posting questions about your ride that has no correlation to the existing thread. Make a thread concerning your own car and get help there.

Thanks for the pointer. Admittedly, I just joined and did not know of that. I just that that this was a group of Chevy Men who were all looking to help each other regardless of who started the thread and to who's car that it applied to. The topic is flowing better TPI and that's the question that I raised. Does everyone share your view.?

RWHP.

Yes, clarifying what he said, this thread is information for you to digest, if you want to know what to do to your project, start a new thread.

This thread is about what we found out that makes a TPI flow better.

Hopefully this info can help you and many others.

What reply post # has the complete engine setup that pulled the 373 Hp? OR, can you give us a new reply with a completed engine mod setup. Pretty please!

Here's mine in the signature. I have another motor going on the engine dyno in a few weeks that I expect over 400rwhp with the same induction system.

How do you think this setup would work on a 406 small block?do you think it could flow enough cfm's.I was thinking of getting a set of SLP's and doing the mods in this thread.

Depending on what mods you are talking about you can get well over 300cfm out of the runners. Intake manifolds as well.

Thanks for the reply.

what specif mods are you referring to...lats listed above.

Don,
I'm curious as to the specs of your intake after the work was done to it. Target torque peak, runner length up to the siamesed point, port diameter/size (both round and rectangular portions), and engine specs. Your engine seems to run decent but I wonder if the rest of the power I think you are looking for might be lost in a loss of synchronization of the intake runner length and cross sectional area for the intended RPM range.

I'm doing some port work now on my '88 GTA and I'm working my manifold in the garage now. I've taken great care to make sure the port length and diameter match the desired RPM range so the engine doesn't fall flat because of complications in the wave tuning effect. I should be ready to install the parts on the car later this week, as well as a host of other mods. The only hard time I'm having is finding someone who can cut me a PROM for that car, as it seems most have gotten out of the business of TPI proms and moved onto the newer PCM's.

I would like to see these flow numbers compared side by side with the alternative Intakes out there ie- MR, SR, HSR, First ect.. Reason being, Im contemplating a 383 TPI boost build, and im torn between keeping and further modifyimg my TPI, or going MR, I really would luv to stick with TPI though.

So Don, when are you going to start selling these by mail order. I think it will bring you ALOT of new biz.

He started with siamesed runners, but they were opened up and the divider wall removed except for the last inch or so and the first inch where the bolt goes through. His tuned length is the distance through the base plus 1 inch.

Dont forget the cylinder head. That counts as runner length, which is roughly 5.5", depending on the head. So his runner length is approximately 13.5". And I'm assuming the ID is still 1.75"?

When comparing the TPI against other intakes, dont look too much into them. For a tuned port, cfm should only be used to judge efficiency of the flow through the runners. Of course, the more the better, but there is more to it than just the numbers the intake puts out. The intake specs are far more important.

I was thinking about this problem about the TPI not flowing enough while riding to work, Could be second hand news but sure it isnt the dual plate throttle body and extremely small intake leading into it instead of the runners? I just recall from my 6 cyl mustang (not saying ford designs better cars trust me chevy does better) but its engine had a much larger fenderwell intanke tube especially down at the end where the filter house meets the intake as well as the throttle body was a single plate that was larger, as ive read someone said that air dosent like to turn corners wouldnt the duel plate design restrict airflow vs having the same size throttle body just with a single plate?

"ive read someone said that air dosent like to turn corners"

That is true. Air has mass and the faster it goes the more it wants to travel in a straight line. That is one of the reasons I have opened up my plenum like I did and also the design of my runners. The bigger the opening the slower the air will travel and make the turns easier. Where you want the air speed is in the actual runner feeding the head to get a ram air effect at the intake valve. Even in the runner there is an optimum maximum air speed that is somewhere around 260fpm give or take.

with your intake/motor setup with a T56,light clutch,carbon driveshaft,long tubes do you think 400rwhp is possible ?

Hey Dyno Don do u think its possible to reach 400rwhp with your intake/motor setup but with 11:1 compression,T56 with a lightweight flywheel/clutch,carbon driveshaft,and full length headers? All that has to be worth at least 20rwhp. What do you think?

I wonder what would happen if you built this motor again with the same intake mods but opted to go with forced induction...just cheat your way to get a lot of air in...lol. I've been getting mixed ideas on my 377 TPI/ProCharged spec'd build but after perusing this thread...I might just go ahead with it....good info!

Yes, I do think it is possible.

Don, I ran what I know about your engine and these are the results. I was assuming a 1.75" ID runner when I simulated it.

Peak torque RPM based on CSA of 2.4: 4770 RPM
Tuned intake length based on 4770 RPM on a 355: 17.6"

Judging from what I can gather, assuming your head runner length of 5.5" and base runner length of 6.5" plus 1" for the runners, I figure 13" of actual runner length so the tuning effect is weak to nonexistent.

I dont know if you were planning on running the manifold as tuned, but since you can't really reduce the CSA, I would lengthen the runner a little if you can to match the CSA in order to boost torque and kick up to a little larger of a camshaft.

Curious, what is the port width and height on your heads?

Have you ever gone to these post?
http://www.thirdgen.org/techboard/al...super-ram.html (Another modded Super Ram)
http://www.thirdgen.org/techboard/al...car-today.html (Dynoed my Car Today)

That looks pretty good! I'm trying to hit 400RWHP/550ft.lbs with mine...

Alot of good info here .A question I have is, refering to your dyno pulls, siamesing the intake almost seems benificial only if you're running large runner heads 220cc intake or larger . Tuning the runners,makes sense, siamese porting down the throat, accelerates the dry air .Once the air is directed down the individual port to the intake, and fuel is introduced, wouldnt porting another open deck under the injectors ,cause an unwanted turbulence. Two banks of air rushing down individual ports, then colliding and mixing fuel, then having to be routed, once again to individual ports .That flat/open spot in the ported baseplate/intake seems more off a hinderance. If intake siamesing was that effective, I would think a manufacturer would make a single oval tube runner to accomodate both intake ports . The dyno, if I read it right only shows a gain of 10hp@ higher RPM, while sacrificing almost 40lbs of torque . doesn't seem worth it unless your running +200mph ,like around a big oval.
Just had couple of cups of coffee(JP-4 jetfuel) and started to wonder if baseporting is benificial and or worth time/money? If racing is the goal then I can see needing the extra ponies to finish the race. But loosing power at the launch , you'll be hoping those 10hp are gonna make-up for lost punch at the start. As for me, Im just building a screamer to hold her own on the street and maybe the occasional Friday night track jaunt.
Thanks again guys

"running large runner heads 220cc intake or larger ."

How did you assume that? Most of us are running heads in the 195-200cc range. Again most of us have gained torque with our modifications.

have you tested diff between high flo TPI base porting and Hi flo base not being ported( deck on runner side) for a hp and torque comparison ,both using siamesed plenum and runners . All components the same except for base porting on the runner side?

The closest was on a 400 cubic inch with a Super Ram. We opened up the intake manifold and and then opened up the runners and at the same time shortening the effective length. The motor made good gains in both the torque and horsepower department. I would have to search for the exact data. Everything else was the same.

I didn't lose any torque

do you have a test run w/out the base port work (on runnerside of intake) .Just tryng to see if baseplate port work is cost effective

"As for me, Im just building a screamer to hold her own on the street"

Then the answer your question is yes. There are choke points in the intake manifold. Plus you can make the transition from the intake manifold port into the head much better.

k i just read through all 6 pages and have a couple questions. has anybody been able to compare different runners on the same flow bench? I would really love to see comparisons between the runners especially with as cast vs. ported. also while I'm bringing it up what's the stock ID for the AS&M runners?

We haven't run any flow tests on the runners, mostly because there isn't much runner left in SLP setups (1 1/2"- 2").

We did flow one manifold with the modified super ram runners, there was no difference in flow with or without them. (300+)

Stock ID on AS&M runners is 1.650.

Here is a dyno sheet on a 350 auto w/ extrude honed TPIS base, extrude honed Edelbrock runners full length (1.660), and extruded honed plenum.
LT4 Hotcam, 1.6 rockers, ported corvette heads, 1 3/4" shortys etc.

i did the HSR swap. love the difference even runs better. alot easier to work on too!

I know that the swirlie heads play a part in that low end torque,these are the 193s cause i have them on my l98 engine,need to find a upgrade of some sort like porting just right.

I just wanted to add we still have not figured out why my engine drops 100+ horsepower at 5700 RPM on the dyno every time.

Also, we tried a 52mm and a 58mm throttle body on Don's engine at the dyno, and it made no difference in rear wheel horsepower or torque.

I remember reading about a possible 383, AFR headed, FIRST intake build that was also gonna be compared. Did I miss the results or was it never tested?

There was a 369" TPI motor with AFR heads that was tested. That one had a First TPI intake manifold, SLP runners and factory plenum. There was a 383 with Edelbrock heads and Superram that was on the chasis dyno and did pretty darn good. Just trying to remember what post you might be talking about.

It was a post by Dyno Don (Page 4, Post 178), but this is a pretty complete thread. I'm sure if this engine had been available to you guys, the results would have been posted. I was just curious.

I did find the results for your post though with the above reference motor. Thanks

i know that the original 193 heads on tpi engines starve for air at the high 5 thousand rpm.i know this one guy who used the vortex heads and had no more problems with high torque end.

Has anyone tried the full FIRST TPI intake set? I would like to see some dyno results with that. From looking at it, siamesed runners would be fairly easy to do. Or just extrude hone them. 1.9" should flow quite well.

Just leave an half inch to 1 inch of divider in the Siamese Runners and that will give you a RPM range up to 6700 RPMs. Find out if your manifold flows at least 310cfms. That too will help you get to 6700RPMs with the ZZX cam. That cam works up to 7000RPMs.