Engine Revs w/ Various Gears @ 70mph

[HAZ-Matt]

Since I did the calculations for a post on CZ28... I have this information, and I decided to post it here just for fun.

The first list is for the 4L60E

At 70mph, 4th Gear 0.70:1

Gears----RPM

2.73------1718
3.08------1938
3.23------2032
3.42------2152
3.73------2347
4.10------2580
4.56------2869

Since I love you all so much, I'll throw in the numbers for the T5...

At 70mph, 5th Gear 0.74:1

Gears----RPM

2.73------1815
3.08------2048
3.23------2148
3.42------2275
3.73------2481
4.10------2727
4.56------3033

Maybe someone should save these numbers, for future generations [img]smile.gif[/img]

EDIT: I fixed the numbers for the T5... I meant to do this yesterday, but forgot.

[ March 01, 2003: Message edited by: HAZ-Matt ]</p>

[dstrbd1]

that lends credence to my notion that i have something bigger than 3.73. i don't know about 70mph, but my car runs at 3k at 75mph.

[speedy-v6-camaro]

I wouldn't count on your tach....most of them aren't that accurate.

[hou-tex-six]

Interestingly my T-5 (with 3.23's) at 70mph runs at approximately 2050 RPMS. You sure you dont have A4 and M5 switched? Seems strange to me...

Cp

[ February 26, 2003: Message edited by: hou-tex-six ]</p>

[Camarorulz]

You're pretty much right on with the A4 3.42s. Mine is about at 2300 rpm @70mph.

[99Camaro99]

<blockquote>quote:</font><hr>Originally posted by Camarorulz:
You're pretty much right on with the A4 3.42s. Mine is about at 2300 rpm @70mph.<hr></blockquote>

I think you're one of the unlucky ones w/o an accurate tach. [img]tongue.gif[/img] Going by the numbers, mine lines up perfectly...just a tad above 2,100rpms! :D

[hou-tex-six]

Something still doesent look right here. For some reason I was under the impression that a T-5 would run at lower RPM's in comparison with a 4L60E with same rear end ratio. Then again I never had any real data to prove it, maybe this proves that wrong, but Im not convinced.

Cp

[HAZ-Matt]

Actually my numbers are a little off... I had used 0.75 as the 5th gear in the T5, but it is actually 0.74... I will re-edit with the proper numbers.

CP... with the same rear end ratio, the T5 in 5th gear will run at higher rpm than the 4L60E in 4th gear because it is a lower gear. 5th in the T5 is 0.74:1 whereas 4th gear in the 4L60E is 0.70:1.

BTW, these aren't the absolute numbers. I used an approximation for the wheel height based on the 235/55R16 tires. There shouldn't bee too many rounding errors, as I did this in Excel...that is to say that there was no rounding until the end, when I rounded the revs to the nearest rpm.

EDIT: When I say they aren't absolute, don't try and pretend like they are 100rpm off. I didn't do any propagation of errors but I don't see why they wouldn't be within 10rpm. Wheel height is the biggest factor... make sure your tires are inflated, have a lot of tread, and are not 245/50's.

If you try to guess what the engine revs are at a certain speed by looking at the tach you have a couple of problems. First of all, the tach is probably not accurate to anywhere near 10rpm... it's only divided into 500rpm divisions, and the needle well over 10rpm wide [img]smile.gif[/img]

Secondly, The speedometer isn't completely accurate either. It's probably reading ~1mph slow if it follows the tradition of standard GM equipment speedometers.

[ March 01, 2003: Message edited by: HAZ-Matt ]</p>

[shortdog273]

Yep, mine is around 2100-2200 rpms also.

[99redcamaro]

i was looking at my tachometer yesterday night [img]smile.gif[/img]

70 MPH 2000 RPM's even
75 MPH between 2100 and 2200 RPM's
80 MPH betwwen 2400 and 2500 RPM's

A4 and 3.42

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by 99redcamaro:
i was looking at my tachometer yesterday night [img]smile.gif[/img]

70 MPH 2000 RPM's even
75 MPH between 2100 and 2200 RPM's
80 MPH betwwen 2400 and 2500 RPM's

A4 and 3.42<hr></blockquote>

I'd bet your tach reads low, or you would have to have higher than stock tire height. I get about 2000rpm at 65 mph w/ my 3.42's.

Interestingly enough... like I posted, 2000rpm is what a 3.08 car pulls at 70mph.

[ March 01, 2003: Message edited by: HAZ-Matt ]</p>

[99redcamaro]

i have to make a correction

80 MPH between 2200 and 2300 RPM's
85 MPH between 2300 and 2400 RPM's

by the way i have Goodyear 235/55/16 and 3.42

[ March 01, 2003: Message edited by: 99redcamaro ]</p>

[99Camaro99]

<blockquote>quote:</font><hr>Originally posted by 99redcamaro:
i have to make a correction

80 MPH between 2200 and 2300 RPM's
85 MPH between 2300 and 2400 RPM's

by the way i have Goodyear 235/55/16 and 3.42

[ March 01, 2003: Message edited by: 99redcamaro ]<hr></blockquote>

hmmm...

I get 2,500 at around 81mph and 2,700 at ~ 86/87

245/55/r16s

[Distephano]

I've got a T5, and give or take 50-100 RPM, thats just about dead on for me :D

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by 99Camaro99:


hmmm...

I get 2,500 at around 81mph and 2,700 at ~ 86/87

245/55/r16s<hr></blockquote>

That's about what mine reads too... but with 235/55R-16