[Keith Seymore]

Originally Posted by GTOnly70

I have a stock 389 tri-power 4-speed, 3:55 posi '65 GTO and there is no way that car is sniffing 13.0 in the quarter...

Our's went 12.90's first time out, but that was after a Royal tuneup. We never made a showroom stock pass in it.

Ran that first season in B/Stock in the 12.40's range.

K

[NeighborsComplaint]

http://www.streetmusclemag.com/news/...o-trans-am-ae/

[mrrat1]

Showroom stock I'd say

68 RA II Firebird
69 RA IV Firebird
66 RA Tri Power GTO

All sticks and 4.33 gears

[judgethis]

The 89 turbo Trans Am like johnta1 said.

[geeteeohguy]

Since this post is about fastest (top speed), it looks like the '89 Turbo TA has a top end of 162mph. Try doing that in anything with a 3.90 or 4.33 rear gear....

[ponyakr]

Originally Posted by geeteeohguy

Since this post is about fastest (top speed), it looks like the '89 Turbo TA has a top end of 162mph. Try doing that in anything with a 3.90 or 4.33 rear gear....

Yeah, looks like we need several different categories here.

Real Pontiac engines--'81 & older.

Any engine used in a Pontiac body-'82-up.

0 to 60 mph time

1/4 mile time

Top speed--mph

And, it needs to be specified if the car must have been as received from the factory, or if super tuning, upgraded exhaust, & dealer installed options are OK.

[bird72]

Working bugs out on the new HO / T400 and for rear was putting in 3.23 to change out 2.73 along with Safe-T-Track but the 3.23 were not up to snuff (used) so mid install decided to just add posi to the 2.73. So hopefully in next week or two can road test that gear with some power vs the 2V 350 that was in it with same gear. I need to do tire / gear calc, but should see better side of 120mph easy, wondering what 5K is at what mph.... Definitely highway cruiser material, but non OD is a sticky wicket. I wanted a road car that would have top end. I see the OD advantage already.... but staying old school... not sure if I will like this set-up....

[Half-Inch Stud]

Originally Posted by camerjeff

a 67 230 OHC-6 Sprint FB yes to around 7000 rpm, I would like to see a stock 250 OHC-6 rev above 6000 rpm. They used weaker valve springs as a built in rev limiter on all the factory 250 engines.

Ahhhhhhhh not the one I had.

[Half-Inch Stud]

Originally Posted by GTOnly70

I have a stock 389 tri-power 4-speed, 3:55 posi '65 GTO and there is no way that car is sniffing 13.0 in the quarter...

TH400 option and you'd be there.

[ponyakr]

Originally Posted by Half-Inch Stud

TH400 option and you'd be there.

My guess is that a TH400 with a stock converter would be slower than a 4-speed, unless you miss a gear or the clutch is slipping.

[Don Keefe]

In terms of box-stock, no tune and stock tires, the 1989 TTA has it hands-down for one reason- there was no vehicle speed limiter. The press event held at Watkins Glen in the summer of 1988 had Pontiac PR people put a chicane in the straightaway, as the press writers were topping 150 and the officials feared a high-speed disaster. The cars had quite a bit left, speed-wise.

Top speeds varied somewhat for the TTAs, but 162-165 was the accepted and was largely determined by the outside air temperature. If you had dry roads and winter temps, that is where my betting money would go. The LS-powered machines would have easily topped that, especially the G8 GXP but they were speed-limited to 155 mph, give or take a few mph.

In terms of a traditional Pontiac-powered car, I have no way to prove it but I think that a '74 Trans Am would win, based on its horsepower and aerodynamics, as well as its forged rods and pistons. I don't think a Ram Air IV-powered anything would last that long above 6,000 rpm with cast rods. Plus, the cars those engines came in were bricks. Why they didn't put the 421 SD rods in that engine is beyond me. The fact that they built so many SR engines proves that they could have saved money by spending the few dollars for good rods.

[mrrat1]

old mans 66 cat buried the speedo on the PA turnpike 389 2 bbl auto & 2.41 rear.
I wonder what a 421 HO would top out at with that rear gear?

[ponyakr]

Originally Posted by mrrat1

old mans 66 cat buried the speedo on the PA turnpike 389 2 bbl auto & 2.41 rear.
I wonder what a 421 HO would top out at with that rear gear?

This might be even a better question. Were the 2.41 or similar gears available in any of the 2x4 421SD cars ? Hey, with the good forged rods, forged pistons, & solid lifter Mac-#10 cam, the 421SD cars could reach some high speeds, with the right rear gear.

http://www.oldride.com/library/1962_...uper_duty.html

https://www.hemmings.com/magazine/mu...y/1281458.html

http://thethrottle.com/2014/09/28/mu...-69-hq-photos/

Fireball Roberts was on the pole, for the '62 Daytona, with a fastest lap of nearly 157mph. And this was back when the cars had the real factory steel bodies. So, on a straight, flat road, with even higher speed gears, how fast would this car have gone ?

http://www.racing-reference.info/race/1962-05/W

[ponyakr]

"...I think that a '74 Trans Am would win, based on its horsepower and aerodynamics, as well as its forged rods and pistons..."


I'm thinkin the 744 spec cam would be the limiting factor. But, an SD455 Bird, with the 041 spec cam & 2.41 gears would have been pretty fast.


"...a Ram Air IV-powered anything...the cars those engines came in were bricks..."

Just curious, how much faster do you think a '74 Bird would be than a '70 Bird, with exactly the same engine/gears ? Or, said another way, how much slower would a '70 Bird body be, than a '74 Bird body ?

[racer_x]

Originally Posted by ponyakr

0 to 60 mph time

1/4 mile time

Those would belong in a separate thread titled, "Quickest Pontiac"

[Don Keefe]

Originally Posted by ponyakr

"...I think that a '74 Trans Am would win, based on its horsepower and aerodynamics, as well as its forged rods and pistons..."


I'm thinkin the 744 spec cam would be the limiting factor. But, an SD455 Bird, with the 041 spec cam & 2.41 gears would have been pretty fast.


"...a Ram Air IV-powered anything...the cars those engines came in were bricks..."

Just curious, how much faster do you think a '74 Bird would be than a '70 Bird, with exactly the same engine/gears ? Or, said another way, how much slower would a '70 Bird body be, than a '74 Bird body ?

As far as the aerodynamics, I wasn't thinking so much about the 88 LS1 1970 Trans Ams that were built, though they were far more slippery than a 1969 GTO or Firebird. Nevertheless, I stand by my statement, as in this case, I think peak torque is more of a factor than all-out horsepower. You can put 2.41 gears behind a 421 Super Duty but it won't have enough power to pull the gear to redline. That's why the NASCAR SDs typically came with 3.42 gears, because that was the highest (numerically lowest) gear they could pull to the redline.

To answer your question, I think that the 455 SD's superior torque would allow it to post a higher top speed than a Ram Air IV-powered '70 Trans Am. The difference is probably not that much, but keep in mind that the '74 has the advantage of slightly better aerodynamics, better peak torque and the availability of radial tires would no doubt add a few mph.

[ponyakr]

"...I think that the 455 SD's superior torque would allow it to post a higher top speed than a Ram Air IV-powered '70 Trans Am..."


Would an SD455 pull to 6000rpm with the stock 744 spec cam & stock lifters ?


"...You can put 2.41 gears behind a 421 Super Duty but it won't have enough power to pull the gear to redline. That's why the NASCAR SDs typically came with 3.42 gears, because that was the highest (numerically lowest) gear they could pull to the redline..."

I've read that the actual hp of a 421SD was about 450. So, with the forged rods/pistons & solid lifter cam, what was the redline ?

[johnta1]

Would an SD455 pull to 6000rpm with the stock 744 spec cam & stock lifters ?

Yes.

[Don Keefe]

According to Pete's second book (page 104), he states,

"At these kinds of sustained RPM's, bottom end strength and oil control are extremely important. Don't think that by using a 2.56 gear, you can it 150 MPH with fewer RPM's. It just doesn't work that way."

He added that "...Average speeds for NASCAR stockers in those days were around 150-155 mph. A 28" racing tire and 3.42 gears required the engine to buzz at 6200-6300 (153) mph) for sustained periods."

[Wareagle]

For Quickness > Jim Mino's 68 400 RA II Firebird ran consistent mid 12's @ 109 mph - stock stroke etc. in the Supercar Showdown series 86-87 - and in one Race embarassed a 87 Buick Gran National Turbo - For top speed the 62-63 SD-421 Catalina is my pic - in one race Fireball Roberts hit around 170 mph - remember these could be ordered as a Factory produced car .