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Need some help improving my L98

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Old 09-09-2007, 07:10 PM
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Car: Trans AM GTA 1989
Engine: 383 HSR AFR195 JRC Cam280/286
Transmission: T56 Conversion
Axle/Gears: 3.27 9bolt
Need some help improving my L98

Hi!

I'm planning to get some more power for my t/a.

At the moment my Engine is bone stock.

I don't know anything about all those cam specs and different cylinder head types, which intake i should use, etc.

In the next months I have to replace my Hydraulic Lifters, so I could spend some more money on some fine parts....

My budget will probably be about 4000$ incl. some of the kind of work I shouldn't do by myself. ( porting heads for example ).

What can I do with that budget?
Nitrous and Forced Induction would be a problem, not really street legal in germany

So I thought of some new heads, another cam, intake+headers and a custom prom.

I'd like to see that my MPG doesnt decrease by those mods.
and it would be great if my engine goes past 5000 rpm's
6000 would be great - for being as fast as a porsche.

some suggestions?
if this information is necessary, my l98 is one of those with 9th injector (cold start) and center bolt - valve covers .

Sorry if I'm asking questions that I could answer myself with using the search-function, but my head starts to ache while reading too much english furthermore i have not much knowledge about engines
Old 09-09-2007, 07:57 PM
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Car: 1989 Firebird Formula
Engine: 5.7L 355 TPI
Transmission: 700 R4 with TCI rebuild kit and valve body mods
Re: Need some help improving my L98

headers and gears make the world of difference in our cars.........
Old 09-09-2007, 08:27 PM
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Car: 1989 T-Top GTA
Engine: 5.7L TPI> 6.2L
Transmission: 700R-4
Axle/Gears: 3.27
Re: Need some help improving my L98

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

Add that link into your address bar....... It's a good article for 3rd Gen F-bodys
It will show you what the different intakes do.
I believe that the engine is a 383 but it will give you something to think about.
Heads....... AFR, Trickflow, Edelbrock, Brodix keep the intake ports less than 200 cc's for improved throttle response on the street ( big ports breathe up high but smaller ports repond better to throttle input..... keep it between 170-200cc)
Cams......... hard one there it's all personal preferance the stock computer will only handle a certain amount of variation from stock. Your camshaft determines where your powerband is. I think Paul Huryk wrote in the facts section of this website that our computers like 112 degrees of lobe seperation. SLP 1992 Firehawk cam was 214/224 degrees duration int/exh and 470/.490 inches of lift int/exh........ you can go higher lift but I think that the stock computer likes this duration........not much more. The higher your duration, the higher in the RPM range you engine is makes more torque/HP
Headers........ Most will say no larger than 1 5/8 inch primary tubes Long/Short, your choice. Shorties work better for automatic transmissions. Check exhaust page......
Custom Prom......... Aftermarket proms suck.... most will say... so you have to learn to program them yourself cause there is no prom begging or chips for commercial sale on this website (Darn!!!!) I have to learn too!!!
Well that's my 2 cents....... everyone will have an opinion though, it depends what you want to do with your car in the first place......Although I will say that I wish that I had $4000.oo bucks to upgrade a couple of things.
(By the way porting is no problem at all)
I would suggest that you read the Third Gen Tech FAQ on the "home" page to familiarize yourself with some valuable information
Old 09-10-2007, 06:26 AM
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Car: Trans AM GTA 1989
Engine: 383 HSR AFR195 JRC Cam280/286
Transmission: T56 Conversion
Axle/Gears: 3.27 9bolt
Re: Need some help improving my L98

@bigchief: i don't want to change my gears
If my 700R4 get's the OD as an fully usable 4th-gear, even at WOT , then i would change to 3.23:1 rearend.

@gta sammy: thanks a lot... interesting article

i've found a program called "Dyno2003", has anyone used it yet? seems to be very easy to use. but would that program calculate a nearly correct hp/tq-curve for new cam/intake/head/exhaust setups?

i could'nt believe, when i typed in the data of a comp cams xtreme ( i think 274-282 .... ) , added full length headers, the peak hp raised to 335hp and peak torque to 450 at only 2000rpm ....
ok, this cam was NOT computer compatible

if i search on summit , i only get "4x4" cams, that are computer compatible.... hmmmm.....
Old 09-10-2007, 01:11 PM
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Car: 1989 T-Top GTA
Engine: 5.7L TPI> 6.2L
Transmission: 700R-4
Axle/Gears: 3.27
Re: Need some help improving my L98

Article on Cams

https://www.thirdgen.org/mods3

THings you should know (GREAT ARTICLE)

https://www.thirdgen.org/mods2
Old 09-10-2007, 02:26 PM
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Re: Need some help improving my L98

i wouldnt do a cam just yet. stock heads wont handle it, or atleast anything worthwhile putting in, so you'll need aftermarket heads or get machine work to the stockers to fit larger springs and decent cam. Not worth it tho

I'd upgrade your intake setup...ditch that TPI and get a holley stealth ram. then look into matching that to a nice 180-195 cc head with a 276 like cam, something in the low 220's intake duration at .050 lift. high 220's low 230 on exhaust side. lift between .500-.550".

That should rev out to near 5800 rpms and make a good deal of power if you tune it right. i expect near 360-375 whp atleast with good heads and tune.

i dont know what you have available in germany, so its gonna be tough to get parts i assume.

But basically, a good 1200 in heads atleast, 550 with the HSR plus maybe 100 in extra parts to bolt it up but that will all depend on how you route fuel lines and what fittings you use, and another 250 for a cam. Tuning will be the part that will be expensive if you cant do it yourself. mail orders can get close but they are hit or miss sometimes
Old 09-10-2007, 03:44 PM
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Car: Trans AM GTA 1989
Engine: 383 HSR AFR195 JRC Cam280/286
Transmission: T56 Conversion
Axle/Gears: 3.27 9bolt
Re: Need some help improving my L98

@sammy: thanks a lot -- bookmarked

@Orr89RocZ : thanks, i think this will help me a lot. most of the parts i would buy from summit, even with shipping an taxes it would be a lot cheaper than buying from german dealers. biggest problem would be the custom prom...
for sure, there are some specialists out there, but they are pretty expensive
Old 09-10-2007, 08:18 PM
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: Strange 12 bolt 3.42
Re: Need some help improving my L98

well i know LSracing chips have some good success tuning these cars. have heard good things about them.

If you do heads and holley stealth ram, they can give you a good tune if you use LT4 Hotcam which is a 218/228 cam. I know one guy was working with the tuner there and got a nice bin for that combination. any cam similar to the hotcam will be close with their tune i would imagine. hotcam and proper heads is capable of 330whp or so. abit bigger cams will net near 350whp
Old 09-11-2007, 02:00 PM
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Car: Trans AM GTA 1989
Engine: 383 HSR AFR195 JRC Cam280/286
Transmission: T56 Conversion
Axle/Gears: 3.27 9bolt
Re: Need some help improving my L98

one question about the HSR :

At Summit I've found the HSR for 310 & 570$ ( depending on it's finish )
Do I need the "Holley EFI Fuel Rails" ??
Would the Stock Throttlebody be ok, or should I use another one? ( 2x 58mm)
thanks

alex
Old 09-11-2007, 02:23 PM
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Re: Need some help improving my L98

you can use any throttle body that works with TPI including the stock one. And yes you do need the hollley fuel rail kit which is an extra 170-200 or so depending on what regulator you go with. I like the idea of a adjustable regulator so you can set your fuel to factory specs or go beyond. But some ppl have had issues with holley's regulator. Mine i have had no problems with so far. knock on wood. Kirban makes a nice unit but its another 110 bucks or so.
Old 09-11-2007, 04:04 PM
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Car: 1989 T-Top GTA
Engine: 5.7L TPI> 6.2L
Transmission: 700R-4
Axle/Gears: 3.27
Re: Need some help improving my L98

Remember you'll have to trim the underside of your hood a little bit for the HSR throttlebody and plum new fuel lines to attach to your new fuel rails
Search some more..........
I'm planning on all the same stuff........ Collecting peices slowly
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