Speed in gears

[renzop]

Does anyone know the speeds at fuel cutoff for 2005+ Boxsters (non-S) with both 5 and 6 speed trannys? And/or does anyone know the rear axle ratios for 2005+ Boxsters (non-S) with 5 and 6 speed trannys?

Thanks,

Alan

[White987S]

Alan, wouldn't the rev-limiter cut-off the fuel at redline? Which is about 7,200 RPM. Should not be speed related but rather RPM dependent.

As for the axel ratios, that should be listed in either your owners manual, near the back, or the 2005 sales brochure.

Edited November 5, 2007 by White987S

[renzop]

Alan, wouldn't the rev-limiter cut-off the fuel at redline? Which is about 7,200 RPM. Should not be speed related but rather RPM dependent.

As for the axel ratios, that should be listed in either your owners manual, near the back, or the 2005 sales brochure.

Thanks for the quick reply. Traditionally rev limiters kick in a few hundred rpm above redline. also I cannot find axle ratios in the 2008 sales brochure and do not have an owners manual.

Regards,

Alan

[seafeye]

Alan, wouldn't the rev-limiter cut-off the fuel at redline? Which is about 7,200 RPM. Should not be speed related but rather RPM dependent.

As for the axel ratios, that should be listed in either your owners manual, near the back, or the 2005 sales brochure.

Thanks for the quick reply. Traditionally rev limiters kick in a few hundred rpm above redline. also I cannot find axle ratios in the 2008 sales brochure and do not have an owners manual.

Regards,

Alan

http://www.renntech.org/forums/index.php?a...&showcat=15

I didn't see the 2005 there but i there is a 2006 and 7.

Page 267

[atld]

You can calculate the approx ground speed at fuel cut off for all gears as follows:

5 sp. forward gears (std 17" tyres)

("current engine rpm"/1000)*5*("transmission gear#")= "x" mpg

i.e. for 3rd gear at redline (7200/1000)*5*(3)=108 mpg

I've noticed that interesting relationship before while driving; the gears are almost exactly evenly separated so you can approx groundspeed knowing only rpm and gear. This is for the 5sp only on the Boxster std.

ATLD

Edited November 28, 2007 by atld

[jayray]

You can calculate the approx ground speed at fuel cut off for all gears as follows:

5 sp. forward gears (std 17" tyres)

("current engine rpm"/1000)*5*("transmission gear#")= "x" mpg

i.e. for 3rd gear at redline (7200/1000)*5*(3)=108 mpg

I've noticed that interesting relationship before while driving; the gears are almost exactly evenly separated so you can approx groundspeed knowing only rpm and gear. This is for the 5sp only on the Boxster std.

ATLD

the final ratio for the boxter is 3.75 and for Boxter S, 3.84. This is why the RPMs in 5th in the Boxter are very close to that of the 6sp. So much for fuel savings with the 6sp. Just google rpm calculator and you can figure out speeds at various rpms knowing a few specs for each boxter.

Edited December 23, 2007 by jayray