EasyC
12-02-2003, 11:44 AM
Ok this is gonna get a little confusing so if you are easily confused....hit the back button.
we all know the stock tire size for a GT-S is 205/50/R16. This would imply a tire that is 73.1 inches in circumference and requires 866 Rotations per mile.
the tire size i have is 205/55/R16 which has a circumference of 78.2 inches and needs 810 rotations per mile ultimately resulting in a speedo reading that is approximately 7% slow.
well through some calculations i figured that with the larger diameter tire i would be driving at 92 MPH @ rev limiter in 3rd (8350 for an 00') while my speedo would read the stock speed of 86 MPH.
So when i brought it up to rev limiter in 3rd i was not alarmed to find the speedo read 86-87 Mph because that is 7% slow....however when my tach was reading 3000 rpm in 6th (should report as a reading of 64MPH on the speedo which is the stock tire size speed at that rpm.) i was shocked to see the corrected reading of 68-69 (which IS correct for my oversized tire).
how could the speedo be supposedly 7% slow at the end of third but not at the middle of 6th? It couldnt be the tach cuz it bounced off rev limiter.
The amazing and somewat coincidental discovery i made was that the speeds that my speedo reports at the end of each gear (rev limiter) match the speeds it should report if my rev limit was 7800 rpm on my size tires.
Can some one please clarify this phenomenon. I am beginning to think that my tach is 300 RPMS off because it hits rev limiter at 8100 RPM indicated (which i always assumed to be 8350). But i own an 00' when the ecu limit should have been 8350....not 7800
naturally if my rev limit is indeed 7800 that would mean that my ecu was replaced with an 02 and it would indicate the Miles on the odo as the miles from the vehicle it was take from right?
we all know the stock tire size for a GT-S is 205/50/R16. This would imply a tire that is 73.1 inches in circumference and requires 866 Rotations per mile.
the tire size i have is 205/55/R16 which has a circumference of 78.2 inches and needs 810 rotations per mile ultimately resulting in a speedo reading that is approximately 7% slow.
well through some calculations i figured that with the larger diameter tire i would be driving at 92 MPH @ rev limiter in 3rd (8350 for an 00') while my speedo would read the stock speed of 86 MPH.
So when i brought it up to rev limiter in 3rd i was not alarmed to find the speedo read 86-87 Mph because that is 7% slow....however when my tach was reading 3000 rpm in 6th (should report as a reading of 64MPH on the speedo which is the stock tire size speed at that rpm.) i was shocked to see the corrected reading of 68-69 (which IS correct for my oversized tire).
how could the speedo be supposedly 7% slow at the end of third but not at the middle of 6th? It couldnt be the tach cuz it bounced off rev limiter.
The amazing and somewat coincidental discovery i made was that the speeds that my speedo reports at the end of each gear (rev limiter) match the speeds it should report if my rev limit was 7800 rpm on my size tires.
Can some one please clarify this phenomenon. I am beginning to think that my tach is 300 RPMS off because it hits rev limiter at 8100 RPM indicated (which i always assumed to be 8350). But i own an 00' when the ecu limit should have been 8350....not 7800
naturally if my rev limit is indeed 7800 that would mean that my ecu was replaced with an 02 and it would indicate the Miles on the odo as the miles from the vehicle it was take from right?