Night Hawk

Here's the deal, the project is a 1988 L98 GTA with the following mods:

3.73 gears
Ported upper plenum
SLP 1 3/4" headers
Edelbrock cat-back
Cold air intake
Adjustable fuel pressure regulator
Crane Ignition
Air foil
All free mods

I would like a nice broad 300 hp power band, the car peaks to quickly and I know it is because of the gears, but I want to keep those in the car. Would new runners such as AS&M large tube runners partially accomplish this? How about Crane Gold 1.6" full roller rockers?

What are your suggestions to reach the goal on a budget?

TheWraith

you want it to pull to a higher rpm, then some siamesed runners are a good start. Ideally, you're best ditching tpi altogether eventually tho.

Ed Maher

Siamaesed runners on an aftermarket base or a miniram are a good start. A cam like the comp XR w/ 212/218 and a mild set of heads.

That'll give you better than 300 peak hp and a much flatter longer torque curve...and it'll work perfectly with your gears.

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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

TransamGTA350

iTrader: (2)

Runners are a must along with a ported lower base. Heads would be next after that. The cam would be the last thing since it is the least restrictive of the setup. Without the cam, you're looking at 300hp, with a cam (something like the ZZ4 take-off cam), you'd be around 325-330hp

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

IROC5.7TPI

I'd try a stock LT4 cam.

Also, if you're running out of breath at high rpms, then I think you need to reconsider your combo. IMHO I think 3.73's are way too much gear for a TPI setup unless its extremely modified and the cam/heads are matched accordingly.

If you want 300 RWHP then you need to get into the engine. I don't think you're gonna do it on stock heads/cam.



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Mike L.
It ain't pretty.......

1987 IROC Z TPI 350 A4 3.27 Borg-Warner.

Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog

http://www.MichaelLasiuta.home.att.net

**BOYCOTT LAPEER DRAGWAY**

Ski89Z28

ROLMAO, TheWraith stop trying to bring him to the DARK SIDE! hehe.
But I think TheWraith is trying to say it'll cost less with a carb.

For a BROAD 300 hp band you will need a miniram, AFR heads and a aftermaket intake and a cam wouldn't hurt.

On the cheaps you could get SLP runners and grind out the seperator in them all the way. This has given a few guys extrs rpms say to 5500rpms but NOT 300 HP. How ever you may not get this 5500rpms with the stock intake and heads.

I'm kinda confused in you question since your talking like you have 300 hp now. But with the mods you listed you don't, well that is what I think.
If your looking to get 300hp out and want to know what mods to do first tell us where the 300hp is at, the flywheeel? Or the rear wheels?
Either way on a 88 model it isn't too cheap!


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89 IROC 350 Auto
MSD 6AL
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
And Free mods.
(stock intake, runners and suspension)

13.879 @ 98.90 mph (with 2.77 gears!)


Moderator of http://www.iroczone.com

Member of JFA Crew

Dan87IROC-Z

A MiniRam intake isn't going to make a very flat power curve. Well, it will be somewhat flat from like 4500 to 6500 or so, but below that, the power curve isn't going offer lots of flat, low end power. But with your gears, and maybe a 2800 or so stall converter, you'll be in pretty good shape.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Catco 3" High-Flow Catalytic Converter, Hooker 3" Aerochamber Cat-Back System, Transgo Shift Kit, Performance Resource Chip, Accel Ignition, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET: 14.32 @ 97.7mph
(corrected for elevation)

Night Hawk

Right now I'm guessing I have maybe 240-250hp from my mods, true? My ultimate goal will be a VERY streetable and reliable 300hp. I'm not too interested in taking out the distributor out of the intake manifold after a nightmare with a 79 vette that I used to own where it wouldn't line up correctly after, eventually it worked but it caused a few sleepless nights and I would prefer not to do it again....anyways, who makes the best siamesed runners out there? They seem like a fairly easy mod to install, true? How much horsies would I gain from the runners out of my current setup? I need to replace the valve seals, so I will get into the valvetrain, is there any suggestions for power there?

fly89gta

iTrader: (1)

LOL Mike...Alex(The Wraith) is going Ram Jet...that little bastard

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Originating member of the SJNEP Crew
Vice President of the Jersey Fbody Crew(JFA)
Check out MyGTA Nicknamed:The Big Red Machine
***AOL IM RiceEatinGTA***
Moderator at www.transamgta.com
"What does not kill us only makes us stronger"

Tony

Grim Reaper

I think you should be saying "Torque" not HP. To have a flat HP line, you would want an engine with a very "peaky" torque line that constantly drops off (sound like TPI?).

Remember that HP is only a function of torque. The formula is HP=TQ*RPM/5252.

If you want HP, you gotta "spin it". What people normally strive for is a "flat torque" line...similar to my sister's bra size.

[This message has been edited by Glenn91L98GTA (edited July 11, 2001).]

Grim Reaper

Damn stupid computer..double post.

[This message has been edited by Glenn91L98GTA (edited July 11, 2001).]

Matt87GTA

Ahhhhhh.............O...K...... bwahhhhhhhhaaaahhhhhaaaaaaa rofl

Kyle F

I like flat chest, as long as they are on older chicks so I am assuming your sister is older than 18, SO hook me UP!!!!! LOL J/K couldn't resist

300HP out of a 350 without removing the intake is going to be impossible without forced induction.

Whgen you say peaks to soon, the only way to remedy that is more RPS, Which on TPI means new Runners and base. The runners are gfood to 4500 RPM and the base is good to around 5000 in my opinion because I had good power up to 4800RPM with a SLP cam POrted Upper intake to match SLPs siamesed Runners.I had about 275 HP at the wheels with that set up, Ofcourse I had full exhaust headers back and all free MODs and lots of time experimenting with the Timing fed by a MSD and the Fuel pressure. I found it all worked the best after I got the 58mm TB, woke the car up, but I also was using a 2200RPM stall converter to.

Do your Homework and MAtch you Cam, INtake, Heads, and Torque converter to give you what RPM range you want. THen you will know what kind of"Tuned" runners to put on you TPI. From there you just build. This will be a easy way to get 300HP that is very streetable on pump gas no problem, infact you should end up with more because I had 275 with stock heads on mine.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

Night Hawk

[This message has been edited by Night Hawk (edited July 12, 2001).]

Night Hawk

Alright then I will change the intake along with the runners, but what combination will give me the nice broad power curve I'm looking for that will work with my setup and gears?

BC86TPI-Z51

The accel intake/Lingenfelter SuperRam...the Large tube runners and intake will never flow like the SR.
You need to push your peak HP higher and a large tube set up, albeit a larger TPI will still run out of breath before you want it to.

With 3.73 gears id say the Miniram as well...Will push your peak Rpm HP higher over the SR...the choice is yours.

PETE

iTrader: (1)

supercharge the damn thing and move on screw the hp when you can try to double the tourqe(good luck putting it tto the ground though)port the intake procharge it andd get a vigillante it will give you some more horse but a lot more tourqe

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87 trans am 350 L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ads strip chip,relocated iat sensor,tb bypass,hollowed maf,a/c delete(whole lotta room in there now)

14.10@97mph w/2.01 60'

slp catback is finally on!!!
saturday came and went no fastchip damn fed ex!!
FLOWMASTER S.U.C.K.S