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      05-02-2012, 10:29 PM   #394
GoingTooFast
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Drives: fat cars are still boats
Join Date: Jun 2007
Location: compensating a fat car with horsepower is like giving an alcoholic cocaine to sober him up.

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Quote:
Originally Posted by BiscottiGelato View Post
I meant at 40mph, with low end torque, I can get away just stepping on the throttle in 4th gear. The complaint is you can't do that on the Toyobaru. My resposne is, drop it into 2nd and rev the darn thing!
If I can drop the Toyobaru into 2nd why wouldn't I do just that also in the 135i or the 1M for that matter?!

I'm not talking strictly about straight acceleration... I'm talking about steering on throttle control at low speeds.

With the Toyobaru the rev limiter in 2nd gear kicks in at 59.2 mph... so, from 40 mph onward a very narrow usable window is left before you need to shift-up into 3rd increasing speed and losing both the low gear torque advantage and, what matters the most, the throttle authority over the chassis.

Let me do the math for you using the above formula:

7450 rpm (BRZ's rev limiter) * k (const.) = 59.2 mph

x rpm (rpm @ 40.0 mph) * k (const.) = 40.0 mph

x = (40.0 mph * 7450 rpm) / 59.2 mph = 5033 rpm


This means that at 40 mph in 2nd gear you don't even benefit of the Toyobaru's engine full potential because you haven't reached engine's max. torque yet which only appears at 6400 rpm.

@ 6400 rpm the speed has already increased to (40.0 mph * 6400 rpm) / 5033 rpm = 50.9 mph

So, you get the best useful window ONLY over 1050 rpm (7450 - 6400) with a max. speed variation of 8.3 mph before you need to shift up.

Whereas in the 135i your best useful window extends from 1200 all way up to above 5000 rpm in each gear.


Do you understand the difference now?!

Last edited by GoingTooFast; 05-02-2012 at 10:42 PM.
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