Transmission gear vs. RPM chart.

[jcammisa@alwaysonline.net (Jason)]

At 12:42 PM 3/18/2002, mathews.rg@pg.com wrote:
>  DO NOT use . 75 5th if
>you do not have a highly modified car and drive highway at more than 65.  The
>engine will have no power when you tromp it.

*SCREETCH*  Whoa there bud. :)

I did the 0.75 with the stock final drive on my stock 1.8 and was fine with 
it.  Of course, there is a difference, but I still never encountered a hill 
on the highway where I had to downshift.

And what's this about a "highly modified car"?   A 2.0 16V with an 0.75 5th 
gear has only 7.5% less power available at the wheels at 120km/h (~75mph) 
than a 1.8 16V does with the *stock* 5th gear.

Therefore, if you have a 2.0 16V, the 0.75 5th will put your midrange 5th 
gear acceleration back where it was with the stock 5th gear and a 1.8.
At speeds over 75mph (where the stock 5th is past its torque peak), at 
*worst*, a 1.8 w/ an 0.75 will have a 17.5% reduction in power.  At worst.

That's not "no power" -- that's slightly reduced power.  Don't expect your 
mileage to increase all that much with the 0.80 or the 0.75 by the 
way.  Mine jumped from 32 to 33 on the highway.  A 
gain?  Yes.  Huge?  No.  The reason is that the 16V's peak torque (and 
therefore peak efficiency) is at ~4200rpm -- which is right around 75mph 
with the stock gear.  Dropping it to 3200 (with the 0.75) does lower revs 
and cause greater throttle openings (both of which add to efficiency), but 
the drop in torque and efficiency negates some of those gains.

YMMV.  (Pun partly intended).
Jason