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Discussion Starter · #1 ·
After searching for some info regarding the yamaha 2UR-GSE and its exploits, the IS-F can actually hit 205 mph up another 35 from its limited 170 mph which incidentally is far and away best in its class! I wonder what the rpms are at 170 in 8th gear?
 

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After searching for some info regarding the yamaha 2UR-GSE and its exploits, the IS-F can actually hit 205 mph up another 35 from its limited 170 mph which incidentally is far and away best in its class! I wonder what the rpms are at 170 in 8th gear?

Where did you get this info?
 

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After searching for some info regarding the yamaha 2UR-GSE and its exploits, the IS-F can actually hit 205 mph up another 35 from its limited 170 mph which incidentally is far and away best in its class! I wonder what the rpms are at 170 in 8th gear?

There should bee a simple way to do the math on this question:

The rear end in the ISF has a 2.937 and the 8th gear ratio is 0.685
Now at 170 MPH what would be the rpms.

Lets just see who can come up with the right answer and how they obtained the answer.

Any real gearheads out there. Who will be the first with the correct answer?


old$parts
 

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Here's a chart on the IS-F's gear ratios.

This was posted on CL by lobuxracer:
 

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Flipside909,

Congratulations you are the winner!
Great information!
Thanks for your input and diligent efforts.

old$parts
 

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Discussion Starter · #9 ·
My friend actually read an article in Japan (he's stationed in atsugi) about the engineering of the IS F. I think an engine designed by Yamaha and the Skunk guys with the venerable 2jz Supra to their credit is more than capable of high end top speed numbers. I mean if a Porsche carrera S with a 3.8 liter 6 can do 190...it makes sense that a 5.0 yamaha racing motor can hit 200 mph with the right tune!
 

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IMHO, one factor not accounted for is drag. i sure the ISF could hit the 180s but drag beyond 186 is a huge factor. I certain ISF is sleek CG wise but do not know specifics.
 

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I just ran my ISF to 171mph and I was in 6th gear at 7,000 rpm in 1.5 miles, with 7th and 8th gear left and some more road I don't know what I could of done. I will have to do some further research. I have a dash video of the whole run.
 
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