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HP gain on TPI 350

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Old Mar 1, 2021 | 09:09 PM
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GreenieG's Avatar
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
HP gain on TPI 350

I've searched around on here about this, most results I see are about building a drag car type stuff, I just use my Camaro for weekend driving and the day here and there taking it to work on nice days. I wanna know what I need to do to get around 300-325 HP at the flywheel. Its a l98 out of a 91 formula that switched my MAF TPI stuff onto instead of keeping it SD, only mods Ive done are when i swapped it i put hooker headers and 3inch catless flowmaster exhaust on it. Other 3rd gen guys i know reckon im at around 260-270 hp right now. So what else can i do to get up to my goal and keep it TPI? My budget is 2 to 3k. I plan on swapping in a T56 at some point as well.
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Old Mar 1, 2021 | 10:07 PM
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From: Northern NY
Car: 1988 Trans Am GTA and 1979 Trans Am
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: HP gain on TPI 350

Your off to a good start with the exhaust mods, that and the intake base seem to be the biggest bottle necks in TPI cars. There are a few options to get in your ball park for power IMO.

1) Order a First TPI set up, $1Kish and you should be there. Get it tuned after and it should be right there. You can also port it for more power. It even looks a bit like factory TPI only larger.

2) Keep it old school TPI and find a aftermarket base like a TPIS big mouth, Accel, or edelbrock on here or eBay. Pair that with aftermarket runners (AS&M still make them for $500) and a ported/gasket matched plenum. Add an adjustable fuel pressure regulator and a new chip..will cost a little more probably with less power but if keeping TPI is important it’s a solid option.

I went with option 2 and my car is a weekend cruiser/sunny day commuter but I have yet to install my parts( this spring). If you want more you could go into heads and a cam but that will likely blow your budget depending on what you choose.
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Old Mar 1, 2021 | 10:24 PM
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From: WA
Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: HP gain on TPI 350

75 shot of nitrous and a fresh fuel system will get you there well within budget.
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Old Mar 1, 2021 | 10:25 PM
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
Re: HP gain on TPI 350

Ok cool, I dont mind doing aftermarket runners, still keeps the vibe of the TPI so Im cool with it. I was initially thinking a stroker kit and all that goes with it but idk if its worth it for just cruising around with. I have the stock 9 bolt 3.45 rear end on mine that should be fine with the HP gains?
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Old Mar 1, 2021 | 10:27 PM
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
Re: HP gain on TPI 350

Originally Posted by Komet
75 shot of nitrous and a fresh fuel system will get you there well within budget.
Yea theres always that as well.
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Old Mar 1, 2021 | 10:49 PM
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: HP gain on TPI 350

Naw, you don't need to stroke it unless you're going to a short-runner intake like a Stealth Ram or Mini Ram.

I made 282 RWHP and 380 RWTQ with ZZ4 heads and cam, headers, TPIS intake and AS&M runners.

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Old Mar 1, 2021 | 11:15 PM
  #7  
GreenieG's Avatar
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
Re: HP gain on TPI 350

Originally Posted by Kevin91Z
Naw, you don't need to stroke it unless you're going to a short-runner intake like a Stealth Ram or Mini Ram.

I made 282 RWHP and 380 RWTQ with ZZ4 heads and cam, headers, TPIS intake and AS&M runners.
Nice, Thats up my wheel house for sure. thanks for the info!
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Old Mar 2, 2021 | 06:34 AM
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: HP gain on TPI 350

Full bolt ons should get you close to 260 whp. First tpi system, go with a 1.6 rocker ratio and underdrive pullies. Maybe even electric water pump. Few hp there.

i would say 260 wheel is close to 300 flywheel
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Old Mar 2, 2021 | 07:31 AM
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From: Northern NY
Car: 1988 Trans Am GTA and 1979 Trans Am
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: HP gain on TPI 350

Originally Posted by Orr89RocZ
Full bolt ons should get you close to 260 whp. First tpi system, go with a 1.6 rocker ratio and underdrive pullies. Maybe even electric water pump. Few hp there.

i would say 260 wheel is close to 300 flywheel
Would he have to worry about 1.6 full rollers with the the pressed in factory studs? Seems like as long as you stay self aligning and have the push rods measured right it would be fine correct? Harland Sharpe and Scorpion have pretty nice full rollers available.
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Old Mar 2, 2021 | 07:45 AM
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From: Mass
Engine: 350 TPI
Transmission: A4
Axle/Gears: 3.23
Re: HP gain on TPI 350

I have a 91 350TPI with bolt ons and put down 250rwhp on a Mustang Dyno in the hot summer days.
TPIS Big Mouth ported
SLP runners ported
ported plenum
airfoil
Dyno Don headers with no cats
Magnaflow catback
homemade "ramair" with K&N filters
AFPR with Bosch 3 injectors
lot of tuning on the AUJP PROM

Id like to get another 30-45 hp out of her but I know it will require heads and a cam and then the whole tuning process starts all over again.

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Old Mar 2, 2021 | 07:49 AM
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From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: HP gain on TPI 350

Originally Posted by Reddragon88gta
Would he have to worry about 1.6 full rollers with the the pressed in factory studs? Seems like as long as you stay self aligning and have the push rods measured right it would be fine correct? Harland Sharpe and Scorpion have pretty nice full rollers available.
yes it would be fine. Doesnt have to be full roller but it helps. Narrow body style to fit under covers
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Old Mar 2, 2021 | 10:24 AM
  #12  
GreenieG's Avatar
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
Re: HP gain on TPI 350

Originally Posted by Orr89RocZ
Full bolt ons should get you close to 260 whp. First tpi system, go with a 1.6 rocker ratio and underdrive pullies. Maybe even electric water pump. Few hp there.

i would say 260 wheel is close to 300 flywheel
Does that First system come with its own ECM?
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Old Mar 2, 2021 | 01:52 PM
  #13  
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: HP gain on TPI 350

No it can use whatever efi system you want
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Old Mar 2, 2021 | 03:05 PM
  #14  
GreenieG's Avatar
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From: Kalamazoo,MI
Car: 1985 IROC-Z
Engine: 350 TPI
Transmission: T5 manual
Re: HP gain on TPI 350

Originally Posted by Orr89RocZ
No it can use whatever efi system you want
Ok cool thanks
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