Inaccurate Tachometer?

sen2two · 06-25-2010, 10:56 AM

I used an safc NEO and an autometer digital tach to check how the stock tach was reading. They both matched each other within 10rpm. So i trusted them for this test. Turns out the higher i go in the rpm's, the more my stock tach is off. At idle, the stock tach is pretty close to correct. And only a few hundred off in the lower rpm's. but close to 1000rpm's off by 7k! That's pretty bad if your trying to get good shift points to better your times.

So you are idling fine at 750 or so. But the higher you go, the more it's off...

*Also, if you changed from the stock tire height (not rim size, but full tire height) then your stock speedo is off.

06-25-2010, 10:56 AM	#6
sen2two KTEC Join Date: Jan 2009 Posts: 642 Rep Power: 0	I used an safc NEO and an autometer digital tach to check how the stock tach was reading. They both matched each other within 10rpm. So i trusted them for this test. Turns out the higher i go in the rpm's, the more my stock tach is off. At idle, the stock tach is pretty close to correct. And only a few hundred off in the lower rpm's. but close to 1000rpm's off by 7k! That's pretty bad if your trying to get good shift points to better your times. So you are idling fine at 750 or so. But the higher you go, the more it's off... Also, if you changed from the stock tire height (not rim size, but full tire height) then your stock speedo is off. __________________ what I have:* 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2 Last edited by sen2two; 06-25-2010 at 11:02 AM.