top speed calculator, accurate?

[CamaroAdam73]

I had to replace the differential in my car, ended up with a 2.41 gear ratio.

Using this top speed calculator, http://www.catherineandken.co.uk/sti/tyres.html, it calculates my cars top speed to be 176 MPH. Really?

My axle ratio is 2.41, TH350 , 265/65/15 rear tires.

Makes me wonder if the engine i built can actually do it.

 

[FE3X CLONE]

That's likely a theoretical top speed based trans, gear ratio and tire size. It doesn't take into account engine power or aerodynamics.

 

[84cutspreme]

Or your tires speed rating

 

[CWPottenger]

Not accurate at all. It does not take into account any real world variables and assumes 100% efficiency and unlimited HP/Tq.

Using that calculator my cars specs would put me into the fastest street car ever built world...

 

[MeanBuicks]

Seems realistic to me. Says my VIN A Cutlass with the 2.41 and 200-4R will go 245 MPH. I'm entering the NASCAR Talledega race with it this year.

 

[CamaroAdam73]

Seems realistic to me. Says my VIN A Cutlass with the 2.41 and 200-4R will go 245 MPH. I'm entering the NASCAR Talledega race with it this year.

LOL i'll meet you there, you can be my top competitor! Realistically i believe my car MIGHT be able to muscle 160 turning this 2.41 gear, it pulls pretty wicket through 1st and 2nd if i let it shift at 4500-5000. 84cut, yeah i doubt my tires would last long at those speeds either.


Has anybody ever seen a good build turning a higher gear ratio like mine??

 

[rustyroger]

It's only a theoretical calculator. My '87 Olds would in theory be good for 170 mph or so, but unfortunately it would be 300bhp short of the power required to overcome wind resistance.
I have heard that some supercars, if driven at top speed, will empty their fuel tanks pretty quickly as they supply the engine with enough fuel to make the power required to push them through the air at 200+mph.....
Just as well in the case of a Bugatti Veyron, less than an hour of top speed driving and you need a new set of tires as well as gas. Maybe $300 for gas, but $20k for four tires....
Makes a BB powered G Body seem like a fuel miser economy car.

Roger.

 

[dogsht]

Even if you have the power a lot of the gbodys tend to start to push & float at around 140 to 145 depending on road rises & dips, wind, tires, suspension, stance etc. Both my GN & 442 would even with factory spoilers, good tires, poly bushings etc. Although the MCSS Aero coupe and Grand Prix 2+2 certainly had the potential to help with this a lot.

 

[pontiacgp]

They run metrics (G body) at Rockingham and they have to have a wing on the roof to slow them down and to keep them stable at high speeds. The design of the rear window are creates a low pressure are which lights the back end plus the air entering the engine compartment creates a high pressure area slowing the car down on a street car. By that calculator my GP is good for 221 mph...

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[CamaroAdam73]

Wow lol. Yeah GP my top speed in that calculator was way out in spare somewhere, i think it said 236 mph. Roger, with my old setup (SBC 355/ 700R4 3.42 GR) i topped the speedometer out at 115MPH and kept going for another 1000 RPM and it got scary, the car felt kind've squirrel-ish.


Are there any GOOD build atricles out there using a high gear ratio like mine? I'm just curious to see, i hate how hard it bit into acceleration, but i love the passing action on the highway.