1978 Trans Am is wrong!

[b1gdav3]

I also don't know who has told them about the Focus ST but my God that thing is terrible, and I've had one since they were first shipped...

 

[kearnej]

top speed for a '78 TA stock pontiac 400 w/quadrajet carb 350 turbo hydramatic trans and eagle st tires is 132 mph proven on I480 in Cleveland,oh in 1987 when gas was $1.04 a gallon...I was really rattled because the hood was shaking really bad....rpm's were never in the red.....

 

[CeltMage]

Car & Driver stated 133 mph for the 1978 6.6 liter 403 Olds with auto trans. I remember reading and dreaming of having that car, but I was 12 back then. Most sites state 132 mph not mentioning which engine. I did own a 1971 Firebird 400 cid that I was slowly turning into a Trans Am but that is another story. lol I miss that car.

Unrelated: My first mod to my first car was a head swap. I put 1972 heads on a 1974 318 and went from 150 hp to 220. I don't know the compression difference, I've never thought to look it up since it was 34 years ago when I did it. lol Chrysler did this in an effort to reduce emissions. I don't remember where I learned to do that but it sure made my Plymouth Valiant Scamp a lot more fun to drive.

 

[Polsixe]

top speed for a '78 TA stock pontiac 400 w/quadrajet carb 350 turbo hydramatic trans and eagle st tires is 132 mph proven on I480 in Cleveland,oh in 1987 when gas was $1.04 a gallon...I was really rattled because the hood was shaking really bad....rpm's were never in the red.....

Weren't they called "shaker hoods" for that reason?

 

[Sick Cylinder]

Weren't they called "shaker hoods" for that reason?

Shaker hoods were so called because the air inlet was fastened to the engine and protruded through an opening in the bonnet (hood). Especially at idle, or when the throttle was blipped, the inlet could be seen shaking relative to the bonnet.

 

[HAmerican]

By how fast I passed the cars with 250 KPH limiters on them, and these people in these 12 cylinder BMW 750iL's didn't want this American car to pass them! I have had several times when I know I was going over 160 MPH. Came across a lot of fast cars over that six year period.

My speedometer would wrap back around, just short of zero before it pegged out.

My 1978 Formula Firebird 400 BB (not modified) wrapped all the way around to 35 before I let off the gas. Likely 165mph.

 

[Torquebeatshp]

You my friend, or no expert.

See my last post.

Try a 2.41 rear axle sometime in a real one.

My ‘77 w/6.6 & 2.41 axle at 80mph was running 2500rpm, I don’t remember the rpm at 120, maybe 3750, but, do remember it was still pulling hard and would hit 140 or close to it. I had been driving a 65 mustang GT, the Mustang was quick but caught a lot of air at speed. The Trans Am was solid at any speed, Bought it new. List price was $7202, I paid $6741.85. No Ttop but was loaded other than that.

 

[eran0004]

Tell me if my math if off, and under this assumption.

Peak power is 4000 RPM

Stock car, at 124 MPH is 5500 RPM, and power curve at at 5500 RPM is 60% of peak power.

160 MPH/124 MPH = 1.29.

It is a square function relationship between power and speed to push a car through the air, i.e. it take four time the power to double the speed.

1.29 x 1.29 = 1.664.

1/1.664 = 0.601.

Looks right to me. The same factory car that tops out at 124 MPH at redline will hit 160 MPH if you change the gears to hit 160 MPH at 4000 RPM.

Since nobody commented on this yet...

The power required to overcome the aerodynamic drag is not proportional to the square of the speed, but to the cube of the speed. The aerodynamic drag is proportional to the square of the speed, but that's a force. Power is not a force, power is the rate of doing work and can be written as force × speed.

So the aerodynamic drag increases with the square of the speed, while the force output of the car decreases linearly with the speed.

We can form an equation:
power / speed = constant × speed^2

Solving for power gives:
power = constant × speed^3

Let s1 and s2 be two different speeds, p1 and p2 be the power required to overcome the aerodynamic drag at those speeds and c be the constant:

p2/p1 = (c × s2^3) / (c × s1^3)
= (s2/s1)^3

So increasing the speed from 124 to 160 mph would require (160/124)^3 = 2.15 times the power, a little more than double the power output, ignoring all other resistances.