It's quite easy to calculate the theoretical top speed of any car if you just know the red line, gear ratios, and tire size. Horsepower and the drag coefficient has nothing to do with it. If you're in top gear and at the red line then your speed will be X, regardless of anything else. Horsepower and the drag coefficient are what determine if you can even get to that red line.

This is simply the first Google hit for "top speed calculator":

http://www.catherineandken.co.uk/sti/tyres.html

I don't have the specs handy but someone can easily plug them in for a 240Z and let us all know what the answer is.

I'd think my four speed would be readlined at 110mph considering it's just a little over 3500rpm going 65mph in fourth. Can't wait until I can one day swap a 5speed in her....

I have had my 76 280 up to 135mph and that is about all she would go with a stock engine. My 1990 TT has hit the 160mph mark one time but it has a couple of mods.

Road & Track showed a top speed for the original 4 speed '70 240Z of 122 MPH. The test data does not say "Est.", which in those days means they actually clocked it.

That said, no way I'd want to try that in mine prior to the installation of the front Spook.

I got mine up to 123 mph in 1974.... clocked by a state trooper with a radar unit. I should have saved the paperwork. He said I was breathing fire out of the rear. I was flat out, with nothing more to go. Today I realize that I am not immortal and would not even attempt it. I don't think that I've topped 90 in the one I have now... Just not enough control of the vehicle at over that speed.

Without aero mods, my '70 starts getting pretty squirrelly at 90 - 95. At 100 it's a near death trap.

I installed a front air dam from MSA and an IMSA-style rear spoiler. Bear in mind that my engine is far from stock, and the suspension is 2" lower than stock. With the aero mods, the Z handles like a rock at any speed I choose to drive. On a near-closed course one early Sunday morning, 130 mph was slightly surpassed with the tach reading a bit over 6500 rpm. Standard 4 speed with an R-180 w/3.36 gears. The car will go faster, but I was running out of road and the tires are only H-rated.

The HybridZ wind tunnel study, published by Nissan MotorSport, indicates that air dams and rear spoilers add sufficient downforce, both front and rear, to keep the S30 planted firmly on the pavement at most achievable speeds....some are better than others, obviously, but they all contribute to stability.

Regards,

Yeah, the R&T test car (bone stock, obviously) ran out of steam at 5800 RPM in fourth gear.

This 70 gets real light in the nose at 90 -95. Anything above that stock and you lose control as was stated above.

up to 140 with power to go. didn't have the guts to keep going. measured with an aftermarket tachometer, assuming that in 79 280zx fifth gear 2350 rpm = 65 mph

I had a gentleman's bet of $1 with the owner of the car most likely to make 150mph using an N/A L-Engine Six Cylinder in an S30 with a stock body (no G-Nose)...Didn't have to pay, though he was close.

Physics is not your friend, indeed it is a harsh taskmaster. For all those with 'stock' 140mph 240Z's, I have two words...

"Speedometer Error"

Or, depending on my mood...

"Bovine Excrement"

And yes, with a G-Nose, 173.325mph on a closed course, in less than 3 miles, from a standing start blowing by like a mother but the fees were already paid...

Actually, in stock bodied cars, I have seen V8's struggle mighitily and not exceed 155. The aero is terrible at that speed, and cubic horsepower really means just that! 350 will get you in the area, but it's still not likely!

Physics is not your friend, indeed it is a harsh taskmaster. For all those with 'stock' 140mph 240Z's, I have two words...

"Speedometer Error"

Or, depending on my mood...

"Bovine Excrement"

You forgot "Tail Wind"

Physics is not your friend, indeed it is a harsh taskmaster

Someone needs to explain all of this to people who post things like

"I have plans for a 1000whp rb26det in the s30, capable of 200+mph"

or ramblings like

"I should get 500 horsies pretty easily with that and 800-1100 with the twin turbos".