Lets hear some top speeds! any 3rd gen just tell us what you have! stock or not.

 

My 87 LB9 gov at 114 but I have a 9 bolt rear end so 107 it really noise dive to it get there really fast I hate it doe give a chance for ppl to catch up (LB9 305 TPI) I have other mods cam headers

 

There are probably 40 different, detailed threads about this.

89 TTA Pace car = 165mph (several mags verified this).
L98 Top Speed = low 15x mph. A few mags have reached "150 plus".
LB9 Top Speed = In the high 14x mph range with M5.
LB9 Peanut Cam Top speed is probably in the 130s because its smaller cam falls off faster, so it has less power overall, and even less power up top.
TBI 305? 130's if lucky, probably more like 120s.
3.1L v6 = 120s if you get past the governor.

My G6 GTP has a governed top speed of 138mph. I've seen it. Grrr.....


Most 700r4s disallow 100% throttle in 4th, automatically downshifting. The one 150mph L98 run I know of was in 3rd, and is probably hosted on this site in the magazine section. I'd need to re-read them to find the exact one.

 

NM, found it first off.
https://www.thirdgen.org/rt_october1...s_camaro_irocz

Not quite 150 for the 86 preview of the L98 87 Iroc-Z. Later L98's had more power, and probably will break 150.

 

holy shizz 149 never thought si but good to know

 

Keep in mind this is a 7.5 mile oval that they were already exiting the corner at speed. So the chances of seeing 150mph in a factory thirdgen is slim. You'd have to have the pedal buried for a LONG time.

 

W/ my LB9 in my 87 138 was as fast as it could go and took awhile to get there.
My 91 w/ current setup ??? My speedo only goes to 145, I can hit 140 at 6000- 6200rpm in 3rd gear....

 

I still have the Car & Driver article from 1989 on the Turbo Trans Am. They got it up to 153 mph. The GTA sourcepage has the article hosted. Quite a fast car at the time with it's 0-60 in 4.6 seconds.
http://www.gtasourcepage.com/8920thTACDReview.html

I can't see any L98 F-body doing 150+ stock. A 1990 Z51 Corvette only made it to 148 mph. Although Car & Driver did note that the 6 speed cars had lower top speeds than the automatic cars. (The 148 mph car by nature of being a Z51 mandated the 6 speed). The 1990 Corvettes with manual transmissions came with 3.33 axles rather than the 3.54 which was available in early 1989. (The change from 3.54 to 3.33 came midway through the '89 model year). So with the 3.54, a slightly better top speed was possible. How much, I don't know.

I'd say with an L98 stock F-body, you'd be doing well to be anywhere in the 140's. Unfortunately most of us (me included) got stuck with that annoying WOT 3-4 no shift "feature" that GM gave us.

 

Scott Kelly, tech. rep for PAS said at test runs at Indy back in 89 it did 171 mph. Don't know if they f^cked with it or not, but I know from experience a paperclip and a crescent wrench can get you 3/10 in the quarter.

 

I can definitely see an average example of a higher mileage L98 losing out on top end where HP is needed the most. A tired engine can be down on power big time. But a well running example should be able to edge over 150.

Several mags state Pontiac said the car's top speed was 161mph (been searching),but I can't find any scans of those magazines. We all understand the TTA was conservatively rated at 250hp since it runs #s that are well beyond the 5hp and weight difference between the GTA and TTA.

I've never tested the top speed on my GTA, never truly opened it up. Closest I got was the standing mile, coming in at 138mph. This is with a bolt-on LT1 swap so its not so accurate in the end. The car has gone 13.3 @ 103 with said engine.

 

Depends on the transmission and gear ratios mostly. If you had a T5, you obviously didn't have to worry about WOT kickdowns like some of the 700R4 cars had to deal with stock. The thing is that the 2.77 rears were bad for top speed as they could never top off 4th (700R4) or 5th (in a T5) at power peak, so you might get 140mph out of an L98 if you were lucky. The 3.08 with the T5 was a near perfect combo, putting the LB9 close to 150mph stock. The L98 with the 3.23/3.27 was also the best combo as it put the car near power peak at around 150.

The TTA was an interesting car as it had the GN 200R4, which has a little lower 4th gear - 0.67 if I remember correctly. It also had the advantage of more power at high RPMS with the 3.8 turbo vs. the L98 TQ falloff at high RPM. Apples to oranges actually.

But, I would love the see what a L98 with the full SLP package would do in top speed as it added a lot of power above 4500rpm and sort of helped the motor around the restrictive design of the TPI intake tract. Thinking around 157 to 160mph.

 

Lol I found out that my car had a ~115mph govenor on it late one night on the expressway years ago. I stayed at that speed for a couple of minutes playing with 3rd or 4th by adjusting the postion of my foot on the gas lol

 

Buried the 145mph speedo in my L98 90 Iroc.