I recently purchased an L98 equip'ed '88 IROC. This is my first 3rd gen Fbody and although I promised myself I'd leave it stock......ish
The bug has already bitten and I want to go faster.

The car has great low-mid range torque but the top end sucks !! It's pretty embarassing to floor it out on the highway and........ nothing happens.

My only mods thus far is a Dynomax 3" converter and cat-back, home-made "ram-air" and I ripped off the smog pump and de-screened the MAF sensor 3 days ago.

I've been reading up on possible options as far as the intake is concerened as I'm well aware this is the reason for the TPI's COMPLETE LACK OF TOP END POWER

Athough Holly's new Stealth-ram appears to have the most potential, I just can't get over the fact it looks like a Kleanex Box . I've always loved the look of the runners on these TPI engines and in my opinion, those alien-looking runners hanging out the sides are what made these things the coolest looking engines produced by GM.

I'm willing to loose a few horses on the top-end by sticking with the traditional runner style over the HSR.

Basically, I've narrowed my choice down to Arizona Speed & Marine's TPI runners. They look stock and from the dyno run's I've seen in the past by those few who actually own them, they are THE TPI runner to beat in terms of both flow capabilities and HP/Torque increase over the factory set-up.

My question to those who run them is, tell me their experience with them? I'm particulary interested in results of cars that were not already highly modified (ie. heads, cam, stroker or power adder etc. etc.) I've seen a few TPI's with these runners dyno throughout the years and all had very impressive results, much higher than what I've seen with other runners, but none of the cars were "bolt-on" cars. In other words, they were all running aftermarket heads and cam so I'm just curious what the results were for "stockish" L(8's with the AS&M runners.

Thanks in advance.

 

i can tell you this from what i have seen/read here.... replacing the runners or base by itself wont do quite that much... its the combination of the two that open up flow.

it be best to port the stock base you have when you put those runners on or else buy a new aftermarket piece too. should be worth nearly .3 tenths or more in the 1/4 from what i seen.

i am interested in the as&m runners myself, except the siamesed ones...

 

Gonna suggest you do a search on TPI INTAKE and FLOW NUMBERS...then back calculate flow vs HP if ya need too...but keep in mind once you remove the runners, the base is a restriction as well...

If emissions is not a concern, I'd really look into the HSR or LT1 intake swap.

The cool factor wears off when a 5.0 blows your doors off

 

Sorry, I forgot to mention tha I'd also be upgrading the base at the same time aswell. (May as well hit two birds with one stone).

So how much HP/Toque would you guess I'd make over the stock set-up on a bolt-on car??

Oh, and as far as getting beat by a Mustang, that doesn't bother me much. This car is purely a daily driver for me. Any performance mods I do are for my own personal enjoyment. I don't plan on racing anything and everything with it. I'll save that for my 10 sec. Firebird. (hopefully 9 sec this time next summer) I'll continue to pick on the Mustangs with my LT1.

With the 3rd gen, I just want a quick DD.

 

the power increases across the band will be nice.... i would say about 20hp would be a nice real life figure... depends tho.. maybe more with adjustable fuel pressure regulator.

 

It's more than a few horsepower. Get over your appreciation of the 'look' of the TPI intake and upgrade to a better flowing unit.

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

I ran 12.5's with an upgraded TPI intake an heads/cam, etc.
With a MiniRam I ran low 12's. With cam/heads that worked better with the MiniRam I ran 11's. Big difference in usable power with a better intake.

Tim

 

I understand what your saying, and it's obvious a TPI intake is not the best choice if you're going for all-out high RPM HP, but as I said, I'm not looking to build a race car or a max-effort street car,. I have my LT1 Formula for that.

I just want a quick DD.

You said you ran mid 12's with TPI. That's perfectly fine with me as I'd be more than content running that number on an every-day car. If need be, I could just spray another 75 or so and run 11's.

My mind isn't made up 100% just yet on the TPI (maybe 95% ) but I'm still leaning toward the AS&M's.

Could anyone post some pic's of their Holley STealth Ram's? I've seen some pic's before but they weren't very good one's. I'd like to see some shot's of the over-all engine compartment to get a good idea of what this thing looks like.

Thanks.

P.s. That link you posted shows some very valuable info. I'm going to bookmark that for future reference.

 

I disagree.
He already has his go-fast car (10 second firebird, not too shabby). If this is purely a bolt-on car...whatever that means...get the AS&M runners, get an aftermarket base, port match everthing, get some headers and a cat-back, and be done with this car. That way you can focus on more important things like getting into sinle digits

 

Hey LT1FUN. I personally have always liked the look of the AS&Ms. They are supposed to be the best flowing intake runners around and they look close to stock. I'd like to slap on a set of AS&Ms and a SuperRam base intake someday (probably on an L98 GTA though). What kind of intake manifold will you be using?



If you're interested in buying some new ones, I have a friend who can get some for you. Ask for Colin.

http://www.performanceplus.com/Qstore/Qstore.cgi

 

Thanks for the link, I'll check it out. As far as the intake manifold, I'm still reading up on that to find out which flows the best.

Any suggestions/reccomendations??

 

Accel seems to be more common, but i've heard nothing but good things about the Edelbrock base.

Whassup Tim?

 

Ask madmax what he thinks of Edelbrock products...

 

I've heard nothing but horrible things about the Edelbrock base...

Soft aluminum, stripping, cracking, etc.

 

those prices are outrageous

but yeah, 12.5's out of a TPI daily driver isnt bad at all

 

those prices are cdn funds. so peanuts to you guys.

 

I had a set of AS&M semisiamesed runners on my car with a stock base, and a ported plenum. I also had ported stock heads, LPE 211/219 cam, and a full exhaust.

For more pics.... http://student.dpg.devry.edu/~d00712...hcie/index.htm
A rolling blast to 100mph just after it was all said and done. This was with 24# injectors, but still a 22# injector constant. VERY rich.



A G-tech once reported 0-60 in 5.2 seconds. Don't know how accurate that is, but it was still quick enough for me.

Now I have a stealthram and it pulls just as hard down low, and way harder up top. Overall it was cheaper than a set of runners and base too.

$475 - AS&M SS runners (I paid $300 for them used.)
$400 - New TPI aftermarket base.
$000 - your time porting the plenum with a dremel or other tool.

The total is about $900 after tax. A Steathram will cost you about $650 all said and done. A LT1 intake conversion will cost you about $550.

And if you are really good you can do the LT1/LT4 heads and intake conversion for about $900 total and go way faster.

There are better ways to spend your money, but if you want to stay LTR then a AS&M setup with a good ported base is the best way to go. Aside from the superram which does not maintian the stock look of a TPI car anyways.

______________________________________________

All of this was enough to keep up with an LT1/M6 car on the highway till about 140mph where I either had the choice of red lining the engine (was already turning 6,000rpm), or letting off the gas so it could shift into 4th at about half throttle.

Pulled on several LT1 cars, Audi S4's and one supra TT (musta been stock) from 40mph on up. I never got the tune right and never had all of the torque down low that it should have had.

 

.

 

At WOT I don't notice much difference. There is some slight bog down low, but so much about my combo isn't stock. Its really hard to say anything solid about a stock HSR swap.

However, there are people on the boards who have done a HSR swap and done a full write-up on it. Esams is one of them I think.

This thread has plenty of info on the HSR swap and its effects on a stock L98.
https://www.thirdgen.org/techbb2/sho...k+L98+dyno+hsr

In the end he gained about 10 peak HP and lost about 40lb/ft torque.

Other repots show guys who have lost very little down low and gained a whole bunch up top. I think I'm one of those people. It pulls hard when its not detonating. It does that alot though, I'm still playing with timing and don't have my chip burning stuff yet so I'm limited to playing with just the base timing.