Saculia

iTrader: (1)

Hi,
I have a 91 formula TPI with the 5 speed manual transmission, WS6 stage three suspension, the 3.42 posi rear end, and all wheel disk brakes. The car also has the dual catalytic converters. I believe that it was rated at 230 hp and 300 ft-lb of torque. I believe that it also came with an aluminum drive shaft.
Does anyone know how many of these were produced (or know how to find out that info)
I was also wondering if anyone knew how fast the car would go. I think that it will redline in 5th gear. I have taken the car to 120 mph and the car was well over 3000 rpm. Would the car be able to do 140 without blowing the engine because of the high revs? At 120 mph it was pulling hard in 5th gear, unfortunately I did not pay attention to the tack to see exactly where it was.
I have no idea of what the gear ratios of the borg warner T5 in my car are. Does anyone have that info.
Thank you for taking the time to read this thread. Any info would be appreciated.

91 formula t5 WS6
underdrive pulleys
K$N air filter
muffler eliminator
Eibach lowering springs.
Sub frame connectors and Strut tower brace

SKFengineer

If you go to the main home page for the thirdgen site you can pick "Tech Articles" from the menu on the left. Once in "Tech Articles" pick the first link I believe it is "calculations" that page has, big surprise here, speed and ratio calculations but the nice part is if you scroll down they give the trans gear ratios for each model year and trans.

Hope that gets you started...

Viprklr

iTrader: (5)

With your setup you should have 245hp and 345lb-ft torque. Same as my 92 GTA.
I'm auto with 3.23's and so far have been up to an indicated 142. Ran out of road. Still pulling but only like a slug.

D's89IROCZ

His is only the 305 though , he said he had a 5 speed.


My current setup ( minus turbo) I had mine burry the 245 speedo easily ( 3.73 gears) and I was still motoring pretty good after it was burried )

Viprklr

iTrader: (5)

Where does he say 305?

Saculia - forgot that your RPO code for the Al DS should be JG1

D's89IROCZ

5 speeds only came with a 305


thats why I say he has a 305 only ....especially seeings how he also said it was rated at 230 hp ( which was the rateing for the dual cat 305 in his year)

luvofjah

iTrader: (2)

My 305 TPI with a 5 Speed, we were past 100 mph in 4th and still climbing...
3.08 gears...

Of course, at some point, the speed limiter turns on... at what point that is...???

Rayvan

You have basically the same set up as my '89 Formula (305 5sp. Dual Cat 3:4X gears). Mine is only rated at 225 HP (because of the crap airbox). I had mine at 140 MPH (read by a GPS) and it didn't seem to want to go much more. There was a headwind, but not too much...

D's89IROCZ

I had that setup before I plopped this one in . Yeah I remeber hiting 160 km's before going into 4th . Took 4th to 170ish km/h . But alas she was limited to 110 mph ( just past 180km/h)

So I say for you ...110mph .

Zepher

iTrader: (1)

with no limiter, 140 should be easy to get to, just may take awhile.

Rayvan

Depends on what the speed rating of the tires that the car came stock with: If you had the Z-Rated Goodyears, there is no speed limiter.

If you had a droptop, they were limited to 105 mph.

Saculia

iTrader: (1)

Thank you for your info.
I have taken the car to 120 mph. There is no speed limiter. The car came with z rated tires. At 120mph she was pulling hard. My main concern in not to cause the engine harm my taking it close to redline. I looked at the calculator, and gear ratios for different transmissions in the tech article section. I think that at 5000 rpm the car is supposed to do something like 150.
Thanks for your replies.

PimpWillis

iTrader: (1)

I don't think the limiter goes by the MPH but rather the tach readings. Mine always started to shut off at 3,000 RPMs. I noticed when I changed the 3.08's and stepped up to 3.54's, I couldn't hit 115 MPH anymore.

Grim Reaper

Actually, all cars have a speed limit in the eprom, just some are set to a very high value. The 305 TPI 5speed & L98s all had Z-rated tires from the factory and the speed limiter is set to 255 mph...the highest setting possible.

All other F-bodies are set somewhere between 110 to 120, depending on the tires that came on the car. Not sure on the convertibles though.

The speed limter can only be changed by modifying the eprom in the memcal. But, unless you actually change the programming within the eprom (very hard to do), the fastest you can ever go is 255 mph. So please keep that in mind if you plan to go to Bonneville to set a new speed record.

Viprklr

iTrader: (5)

Duh. My bad. The dual cat thing kind of messed me up as well. I thought only dual cats came on the 350.
----------
Yeah. 140mph+ headwind.

Zepher

iTrader: (1)

it's MPH, not RPM.
If you change to numerically higher gears without re-programming the chip or putting in the correct speedo gears, the car will have a lower "real" top speed.
Example, on my friends 91 305TBI Auto, he went from 2.73 to 3.42 gears and at 92mph (real speed) his speedo would read 115 and the limiter would kick in.
I reprogrammed a new prom for him with the limiter raised to max.

Grim Reaper

Absolutely correct.

It is actually best to do is also change the speedo gears as certain eproms/ECM combos utilze the VSS for various things that can greatly affect the proper operation of the engine and torque convertor (autos).

Andy 91GTA

iTrader: (2)

91 & 92 350 TPI Firebird's came with 240 hp and 340 lb/ft of torque. They had a more restrictive air intake than the Camaro which is why they made less power.

91 Formula

iTrader: (1)

I also have a 91 formula ws6 with the t5. I have pegged out the speedo and still climbing to around 160mph with the hypertech chip. Just do some tuning to it . Mine is hanging with the stock LT1. With alittle work you can really pull some power that you will be happy with

Viprklr

iTrader: (5)

I believe that. Chevy always got better numbers than Pontiac because it's a chevy engine. Apparently then the 91&92 bird specs are wrong at our home page.
That's crap. Pontiac is an upscale Chevy.

Grim Reaper

Actually, it's a marketing issue and it depends on which publication you look at. In 1990, they were rated 240 but in 1991-1992 they were rated 245. I had brochures for my 1991 L98 GTA that stated 245 HP (which I wish I kept)as well as my 1991 Factory Shop Manual lists 245 HP.

The biggest mistake people make about the 1991-1992 L98s is the compression ratio. It was increased to 9.75:1 in 1991 by use of a different piston (though I am sure someone will claim it was actually done in 1990).

Again, my GM Factory Shop Manual clearly states the compression ratio as 9.75:1 and I have had this confirmed years ago by GM that 1991 & 1992 L98s had 9.75:1.

But, in the real world, 5 HP is insignificant. And, by opening up the air filter cannister, you can make the intake breathe better on a Firebird. In fact, with proper CUSTOM tuning of the eprom (NOT an off-the-shelf eprom), you can easily obtain another 30+ TQ from the mid-range to top-end and get another 30+ HP at the top-end. And, with some tuning and invoking Highway Mode, you can also get a 10-20% increase in fuel economy.

Viprklr

iTrader: (5)

My Helms also states 245hp and 9.75:1 compression.
I've had my joys in prom burning. Once I get everything back together again I get to delve into that world once again.
Definitely should've kept your 91 GTA.

90 white Z

Why would you possibly want to go that fast

Zepher

iTrader: (1)

Because it is fun.

Steve86TA

iTrader: (57)

Make sure you let us all know when and where you will be doing this.I dont want to be anywhere near this

jack harrison

my 87 t/a done 148mph on a dyno run in third gear (700r4). it only has a 140 speedo, any ideas what i could run if it went into top gear? the engine is a 350 tpi our of a 91 gta. it has heads cam borla and headers. oh and 3;73 rear.

Zepher

iTrader: (1)

maybe 155. On a Dyno there is no air for the car to push through so you are only limited by your RPM and gearing.
On the road, the faster you go the more power the car needs to push through the air. It gets exponential, to a point, as you approach 180mph.
Example, 300hp can get you to 180mph but to hit 200 you will need 600hp.

jack harrison

that would be good!! sure puts a smile on my face when im the highway! not that i break the speed limit not bad for a 20 year old car! oh and according to my time slips ,with nitrous, she'll do 0-60 in 4 seconds! porshe eater!!

FeNyX_6

I had a last week produced Van Nuys 91' Firebird Formula LB9 5spd (Black/with a grey interior and had the dealer take the decals off) with T-tops(GVW 3050) ... with my brother and a friend in the car on a trip upstate and a full tank of gas we just stopped to get, I hit the fastest I could get it to go ... that car was awesome, and some people I met who worked at the Van Nuys plant have said the late production cars had more oomph than earlier ones in '91, as there were so few orders for V8 Firebirds and Camaros in 91' cause everyone was waiting for the 4th gen to come out and that legendary plant was closing ... also why the 92's are just holdovers from '91 ... 1st went to 45mph, 2nd 0mph and 3rd 90mph, 0-100 was ridiculously fast, and what I wanted, but after 110 in fourth it crept and took over a mile to get up to my fastest 135 mph in it ... My 0-60 clocked was 5.0 secs adjusted and my clocked 1/4 mile was 14.8 secs @ 108mph ... STOCK, before I upgraded the ignition and some other things ... only did those things once as my life changed completely shortly thereafter ... good times ...

Tuned Performance

iTrader: (92)

cool story bro, sure everyone in this 07 post will enjoy the read.

Viprklr

iTrader: (5)

Oldie but goodie.