anondude13

http://www.holley.com/HiOctn/ProdLin...FMS/SR/SR.html

ditchbangr

iTrader: (1)

There have been a couple write ups on the HSR in camaro performers and I just got the new chevy high performace issue and they install the hsr on their project camaro. My machinist does alot of dirt track carb. stuff around here. When he did the 406 for me and I dripped off the HSR for it you should have seen his eyes they got as big as 8 *****. It is a pretty trick looking piece, especialy the base. We kinda live out in the sticks I guess, for performance cars here in MN.

ditchbangr

iTrader: (1)

DP

grumpyvette

the one major factor most of you are ignoring is that all the intake manifolds are designed to operate at differant rpm ranges and if the compression and cam used does not exactly match the intakes rpm range the intake will produce far lower numbers!

my PORTED STEALTH RAM produced far better power with both a CRANE 119661 and CROWER 00471 than with cams that worked correctly with the PORTED TPI with high flow runners

grumpyvette

the one major factor most of you are ignoring is that all the intake manifolds are designed to operate at differant rpm ranges and if the compressionratio fails to be correctly matched to the cam and if the cam used does not exactly match the intakes rpm range the intake will produce far lower numbers!
then your also ignoring the fact that once the intake flow exceeds the heads flow potential , the intake will show no significant gains past that level significantly reducing the hp/tq numbers the intake test will show yet the intake still may have far greater potential and the fact that the larger the displacement and higher the compression the more effective the high flow intakes become!

my PORTED STEALTH RAM produced far better power with both a CRANE 119661 and CROWER 00471 than with cams that worked correctly with the PORTED TPI with high flow runners

Rockin-Iroc

You make sense. You are absolutely correct. It's all in the combination. For most people, a perfectly-matched ported TPI would feel very adequate and quick in their street car. But I can completely see the potential of the Stealth Ram. I might try a Stealth Ram myself when I stroke my engine to a 383. I'd also like to get a pair of those Vortec heads. I'll probably get iron and then ceramic coat the combustion chambers like I did the Corvette's big block iron heads. That will add some additional octane tolerance.

DON 88T/A

The Mini-ram "only" peaked at 6200...
I've seen other MR combos pull much higher...if they were using unported trickflows like mentioned way back along with a smaller TB it would have really held back the MR.
The stealhram is a nice peice but was done @6000..yes it would have faired better with a bigger set of heads too...the MR held 500hp for 600+rpm's...
Like said above each intake has its strenghts..put a set of hogged out afr210's on that motor with a solid roller..and then you'll see what the MR is made of.
The fact that the MR only made 50 more hp then the TPI is very telling of how choked it was up top...big cams are great..you need big heads to work with them.

Red Devil

That was from the magazine themselves, so yes, the TFS heads were unported.

Bill Speed

What happens in the octane range? Many magazines hint at just going for a LS1/LT1 or other engine with more modern attributes. Both projects look relatively costly in a car known for traction problems and body flex (unibody! ha)
I'd be looking to stay at 91/90 octane and going to a max 350HP increase, just to keep the car economic, also being a daily driven convertible. Low end torque tends to suit me.
Bill

Rockin-Iroc

This is just my opinion, but if low end torque suits you best, then the stock-style tuned port is probably the best option for you. However, you can update the heads to something like a Vortec head, which will give you the best bang for the buck. And then definitely get a better cam. The stock cam leaves a lot to be desired, it is TOO mild. My stock tuned port responded beautifully to the Iskendarian 270 Mega-Cam. I also zero decked my block and shaved the heads to get 10:1 compression. (This is on a 350).

Maybe at the most, you would want to upgrade the tuned port tubes to larger tubes, but the stock tubes DO build nice torque, and if that's what's important to you, then the above modifications might be good.

GMPP sells a crate motor with Vortec heads that makes 330 hp with only 9.0:1 compression. This is pump gas friendly at any altitude. Some magazine had managed over 400 hp with these heads at a higher 10.4:1 compression. (Hot Rod, I think). So your goal of 350 hp is possible. I'd like to swap my ported stock heads for a set of Vortecs myself. I think I'd see a large gain.

okfoz

The problems I forsee with the Vortec heads is the following:

1) The available lift on them is limited, I think the highest cam lift is about .490, so you need to modify them to accomidate higher lift cams.

2) The bolt pattern is different than the 87-95 standard SBC, and either you have to modify the head to bolt to the intake, or modify the intake, or get a different base (I believe Scoggin-Dickey or something like that makes one).

Otherwise I would have already gotten a set.

John

Dave Farr

for those of us that value the info presented in 3rd gen but prefer trucks, what is the best choice for mid range torque. have an 89 k1500, 5.7l, vortec heads, 700r4, 4.10, 31" tyres, 6000lbs, currently with edelbrocks tbi to mpfi conversion kit and ported tb flowing 640cfm- works well but always liked the tpi looks but not the rpm limit, need to pull to 5500rpm. i like the engine masters competition- its not the peak power, but the area under the curve. was thinking of the hsr but am afraid of loosing too much grunt down low. am going to use an engle hyd roller 477/479 206/212 @ 050-114 deg, too many problems in the past with low vacume and speed density.

robsgta

Go with a stroker crank a 383 or 396 will help pull that truck with a lot more umphhh.

Rockin-Iroc

And switch to TPI. Best truck motor GM ever made...except that they didn't put it in a truck.

I am pretty sure I've seen base plenums for sale from GMPP for the Vortec heads. Plus for a small fee, a good machinist can easily machine the Vortecs for larger springs. Or you can buy them that way, already fitted with larger springs.

kdrolt

I think the proper saying, as I've heard it is:

"TPI - the best truck motor GM never made."

On the converted LT1 intake -- if you look at a Miniram, inside & outside, it's virtually the same as the LT1. So I would expect similar results for the converted LT1 intake as for the Miniram.

Dave Farr

well with fuel prices topping $1.05/liter here the 350 will stay a 350 i almost went 383 but didn't. collecting pieces for torque via edelbrock/vortec base, slp runners, will try a 48mm tb first, 24pph ford injectors should get me in the ballpark. by the way looking for 89-92 hi flow runners...

vbMike

iTrader: (2)

This is kind of a dumb question but whatever. I have a 87 L98 350 that I plan to put a ati supercharger on as soon as I get the money. Right now the car has the stock TPI intake. My question is, if I supercharge the engine and then later switch to the TPIS bigmouth base, larger tube runners, a 52mm throttle body, and ported plentum will this increase the hp if the engine is already supercharged. I assume that it would help but when I think about it like if I ramming 9lbs of boost down the stock intake or 9lbs down the TPIS in take will is make a difference. After all 9lbs of boots is still 9lbs or am I thinking about this wrong. Will the TPIS intake allow the air to be more free flowing and there for give me more power?

okfoz

vbmike
I did not know that there were Superchargers currently available for 85-87 F-bodies. Or are you converting over to the serpentine belts from an 88-92 car?

John

robsgta

Vb Mike thats a good question.
Anything that helps speed the velocity(porting but mostly polishing intake) of air or increases the density (intercooler)flow of the boost entering your motor will give you additional horses.
If you get a 9lb boost ATI and a boost gauge, your going to see that it doesnt necessarily guarantee your going to get exactly 9lbs of boost . Every ones set up is going to be a lil bit different according to and inluding the angle of bends that the air flows the diameter of the tubing and any obstructions will impede air flow like Maf screens left in size and type location of the air filter used.
Try to get a good exhaust as well I collapsed a single 3 inch flow master with a 12 psi ATI a few years back, made me think I blew my motor when it happened.

VincentZ28

iTrader: (2)

Paxton makes a S/C for 85-87 TPI cars. It's been around for about 17 years.

vbMike

iTrader: (2)

As far as I know the paxton kit for the 85 - 87 has been discontinued. I am planning on doing the serpentine swap. I alread have hooker headers and a 3 inch hooker cat back so I'm all set there.

Hey robsgta, so your saying that a new intake will help out with the hp even with the supercharger? Do you think the intake gains would be more or less with the supercharger than without the supercharger? I'm just trying to figure out if the money for a new intake is going to be worth it if the cars going to be supercharged.

Acceld Z

.......and sucks the big one compared to the ATI or Vortech gear

Rockin-Iroc

I drove a Paxton centrifugal supercharged 305 TPI IROC-Z Camaro before I bought the IROC I have now. At lower rpm's the 305 still felt like a 305. But in the midrange to upper rpm's, the centrifugal supercharger would start "pulling" and the 305 started to feel impressive. I also noticed that the tuned port engine, which normally would have fallen on its face around 4500 rpm in stock form, pulled much higher than 4500 rpm with the supercharger. It was obvious that it WAS force-feeding the engine beyond the tuned port's designed rpm range.

However, larger runners, base plenum, ported top plenum, and larger TB would definitely make a difference. You would see an increase in power as a result. Just as without a supercharger, opening up the flow into and out of an engine results in power gains.

One place to look for a supercharger is in swap meets. I always see several various superchargers for sale there, and for bargain prices, compared with new. You could also check on e-bay, but it's harder to get a good deal on e-bay. There's always someone with more money than you willing to spend stupid money on anything and it's kind of hard to win bids.
But you could get lucky...it's worth a try for the savings.

robert1

iTrader: (3)

Did anyone ever figure out how to get all this info to print in a normal frame? Thanks.

Thirdgen89GTA

iTrader: (5)

Little button down at the bottom of this page called "show printable version"

robert1

iTrader: (3)

I tried that, and have wasted a bunch of paper! It's also different because of some post widths. I just printed a few pieces of certain pages that I needed. Thanks anyway.

Thirdgen89GTA

iTrader: (5)

You can always print just the images themselves.

Here is another option.

hit the printable version, then select the text you want to print. Right click on the text you want to print and select "print" from the pop-up menu. Then under page range in the lower left hand part of the dialogue box click "selection".

It will only print the parts there were hilighted.

robert1

iTrader: (3)

I had two problems with that too. When I right-clicked, "print" wasn't highlighted for me to click on. Once the printer was open, "Selection" wasn't highlighted either. Ah, I'll just skip it, and read it when I want to. Thanks again people.

grumpyvette

http://stealthram.com/flowcomparison.html

http://stealthram.com/intakecompare.html

http://www.lt1intake.com/

http://www.eecis.udel.edu/~davis/z28...age021105.html

http://www.eecis.udel.edu/~davis/z28...age010511.html

http://www.eecis.udel.edu/~davis/z28...age031229.html

http://www.gmhightechperformance.com...holleystealth/

you may find this interesting,,, what youll find is that a mildly ported HOLLEY STEALTH RAM will give an exceptioal and well matched power curve to a engine combo designed for maximum power PROVIDED the cam ,compression and rear gear ratio are designed to match the 3500rpm-6500rpm power range the intakes designed for, and that a stock or mildly ported TPI is designed to match the stock rear gear and rpm band of the stock engine at a much lower 1500rpm-4500rpm power band.

yeah before you point it out, it won,t in un-modified form fit under a stock corvette hood, it has no EGR provisions, and yeah youll loose some low rpm torque potential but more than gain back extra power at high rpms to compensate!.. yeah, a high stall converter,cam,and rear gears are necessary to get it all to work correctly

Rockin-Iroc

The reason the stock TPI falls on its face at 4500 rpm has more to do with the ridiculously wimpy cam GM chose to use with that engine, and the highly restrictive log manifolds. I can't believe GM was trying to bring back horsepower during that era. They were making obvious mistakes.

I wouldn't underestimate an ideally matched TPI. You can get another 700 or 800 rpm out of it by putting a better matched cam in it and freeing up the intake and exhaust. As with anything, it will respond nicely to standard run-of-the-mill hotrod mods.

You can think of the TPI as boosting torque like a nice dual plane intake would, and the stealth ram as boosting top end power like a nice single plane intake would. It all depends on your combination and what is more important to you.

Personally, I prefer the VERY strong torque of my TPI, which also responds well to higher stall and good gears. But to each their own.

1989GTATransAm

iTrader: (3)

Yeah, you basically have to make it a "deTuned Port Injection".

Jim 86 IROC

Thanks much for this info and the article.

Though I still have the '86 IROC I'm mostly working now on the '88 Vette.

For those wanting to use the #113 Vette heads ('88-'91), be aware that they may be a little weak for much over 400-450chp.

89IrocZ350TPI

Wow thats a pretty cool article.

Jim 86 IROC

The cam & heads have a lot to do with power band, though a stock TPI limits air flow much above 5k RPM.

I've done the siamese intake base mod (first shown on this Forum) on the '88 Vette and, along with 1.6:1 RRs it now pulls well to 5,800rpm with stock cam, heads and exhaust headers.

There was of course a little low end torque loss but going from a 1,500rpm TC to a 2,000rpm unit more than compensated for that.

Though it still "looks" stock it must now be condidered a "modified TPI".

Rockin-Iroc

Yeah, if I ever build that 355 into a 388 (3.75" stroke, 0.060" overbored), that's probably what I would do too.

For those that don't think the TPI is worth a turd, I just pulled on an LS1 5th gen Vette. He couldn't match my torque. If midrange torque is your goal, it is really hard to beat the torque output of a TPI.

okfoz

What I find intersting is After the TPI GM went to the LT1 where they emilinated the tuned intake... But the new LS1,LS2,LS6 & LS7 are all back to the tuned intake. Its funny how things come and go. I noticed that about the time Chevrolet droped the TPI in 1992 Buick developed their own tuned intake for the 3800 as well...

Although possibly crude to some people I think the TPI has a lot of potential, and could run easily with the LS1 with the right setup. From what I understand from the LS series engine is there is alot of technology in the heads that really help the power.

John

Rockin-Iroc

Tuned ports use the concept of "Inertial Supercharging". That's what boosts their torque. The disadvantage is that the range of rpm is limited, and GM chose the range most often encountered in everyday street driving 90% of the time in the TPI. This limited top end horsepower, so in the "numbers game", TPI loses. A lot of people today are too concerned with "horsepower" and don't realize that 90% of the time, it is TORQUE they are feeling, torque pushing them back in their seat, and torque that blows away another car from a traffic light. TPI was designed to increase torque. With the right modifications and combinations of parts, TPI is still a very powerful option.

I had the opportunity to have a carb on a modern dual plane AND TPI on the same 355 engine. The TPI is quite a bit more powerful on that same engine with no other modifications. My old induction system was a 650 Holley double pumper on a Wieand Action Plus dual plane.

Besides the obvious boost in power, I am enjoying 5 mpg better gas mileage with the TPI.

So why do people hate it so much? I don't get it. When I can outpull a C5 Vette off the launch (okay maybe not top end, but definitely up to 60 mph or so), I can't understand why the TPI has such a bad reputation. My guess is because a lot of people give up on it rather than trying to improve it.

okfoz

I think it may go to the mentality that its "old Technology" Its like talking about the Buick 3800 to some people. THey think since its an old pushrod engine that it should be retired. It was suposed to be retired in 2000, then 2003 and now 2007... Funny thing, it works well, it runs forever, its quiet and refined to a good little engine. But its good technology and should be remembered.

In the same way the TPI engine was one of the first if not the first Tuned engine with Fuel injection by GM. They learned alot from it, unfortunately they will probably forget and re-invent the engine all over again... Someone will have a great idea, only to realize that it was already done so long ago.

The neat thing about the TPI engine is it is so versitile with some simple tuning.

John

robert1

iTrader: (3)

I think that they "give up", just because it's old. I agree that it is the ONLY way to go for good mileage, low torque, and reasonable cost. I'm rebuilding my 350 to a 383 now, and am keeping my big-tubed TPI. The only thing that I'm doing is getting it Extrude Honed, for better flow. Other than that, I'm VERY happy with the driveability of it as a 350, and mileage.

Rockin-Iroc

I once came up with an invention for a TPI. By combining the long tubes of the TPI with the short tunnel ram tubes, like a Holley Stealth, and then a sliding plate within the upper plenum to block off the tunnel ram ports for lower rpm operation, you could have the best of both worlds, sort of like the ZR-1 engine built by Mercury Marine. I was never sure how to build it though. Probably by starting with a carbureted tunnel ram intake and somehow heliarcing the individual tubes to the lower part of the tunnel ram's ports, and then building an upper plenum box. Then the question arose of how to actuate the slider plate to expose the tunnel ram ports at the right time. Computer control maybe, or vacuum control.

But I decided it probably wasn't worth the trouble, just to pick up a little bit of top end. If I had more money and resources, I could see experimenting with something like that, but I don't.

okfoz

Kind of like a trombone?

John

Rockin-Iroc

kind of. More like a sliding valve that would open up a freer breathing set of ports. I think the Corvette ZR1 used a similar principle.

5.7tpiroc

im in the process of putting my converted lt1 intake on my 5.7, it would've been pretty neat to see that in comparison to the hsr's, and mini rams, etc. considering they are all $650+ and mine was only $75 (got a great deal)!

Red Devil

Certain other members have come up with similar ideas years ago, most from the SHOs set up over a ZR1's. Making it or something similar is actually being worked on from my understanding, along with a few other ideas as well. Doubt they'll hit market but... :shrug:

Rockin-Iroc

I've done some reading in an old issue of Corvette Fever magazine, concerning swaps from the L98 TPI induction to a higher rpm Miniram intake. The C4 Corvette's stock gears were 3.42:1 and it was running a 700R4 with a 2500 rpm stall. When they made the initial swap, they noted that the engine revved higher, but was still limited due to the very small L98 camshaft. They also slowed down quite a bit in the quarter, because although they removed the rpm limit of the TPI, they also gave up a HUGE amount of torque in the conversion, and the old combination was PERFECT for the TPI's torque curve.

The next step in the conversion was to put a larger ZZ9 camshaft in the engine, some ported heads, and a rear end gear change to 4.10:1. And THEN they improved their 1/4 mile ET's to between 0.1 and 0.2 seconds quicker.

...Hardly worth all the expense they incurred.

Corvette Fever's advice was to use the larger plenums and runners, and the larger throttlebody, along with a larger camshaft, and keep the TPI system, just because it's all about the whole combination.

seanof30306

iTrader: (4)

http://www.compcams.com/Community/Ar...?ID=1737510521

I found the article on the Comp Cams website. I'd suggest everyone interested copy it; you never know when they'll take it down!

seanof30306

iTrader: (4)

I know this is old, but, sorry, I disagree. Just because the engine is not INCREASING hp doesn't mean it's stopped pulling. That engine is continuing to increase it's rpms (and therefore accellerating) at the same hp level. It will not have nosed over until that hp number begins to drop.

As I understand it, once you hit peak hp, the next relevant issue is where the shift recovery will place you in the torque curve. Ideally you want to fall right back into the torque peak, or just slightly below it. That 1600 rpm hp "sweet spot" gives you a lot of room to work with here. Normally, you're forced to find a compromise, either having to rev past the nose-over point to place yourself in the ideal torque range, or shifting at the ideal HP point and falling below the ideal torque range. You wouldn't have to do that here, nor would you with several of the other LTR setups they tested.

Archaea

so I'm building a 383 right now...I have the stock Intake with the ported base matching my 113 heads...

Would I be better off for a daily driver using the TPI? or a Superram with a Edlebrok high flow base?

Archaea

newest link that works!

hosted by compcams

Articles That Use Comp Cams® Products

robsgta

Hey Archaea, your 383 will make a great daily driver. Since most of your driving will be at the lower rpm and hp ranges.(buy some Nitto drag radials first)
The off the line torque is nice for light to light driving but the intake will be choking your motor. The stock intake even ported and matched isnt enough for a stock 350 that wants to rev past 4500 in the quarter mile. ( go to a Holley Stealth Ram )
I have had the same delima that you will be having. My motor stops pulling right at 4500 rpm's.
A stock 350 with bolt ons and an after market intake will be able to keep up with you if you keep the stock intake on.
The stock intake has no place sitting on top of a stroked or heavily modified motor unless your going to be using forced induction; "NOS,or some type of charger "

Rob