The "how high should i rev?" thread

[Porch]

So, someone posted this:
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Reading through there, we have:

ALL LS1 cars, no matter the yr, have a 6200 fuel cutoff from the factory.

a ~6700 rev limiter (Z06's)

A rev limiter is not something that's intended to be reached. It is there to prevent damage. If you're shifting on the rev limiter, you're losing.

If you have a 6700rpm rev limiter, and your car makes peak horsepower in the 6400rpm range, then you should be shifting at your peak power. A stock LS1 hits peak power in the 58-5900 range, an LS6 in the 6400 range.

Personally i read a lot of stuff on the internet, but i wouldn't consider it a fact (i mean, you should see the stuff they post at HondaTech.com!!!). I built a 7500rpm SBF a long time ago, and i know what goes into it!

Not saying you can't spin these motors that high, just saying that I wouldn't try to build a motor to rev that high for something i daily drive, and I wouldn't expect it to live long at those rpms. Now if you have an LS7 with titanium rods, THEN we'll talk

[xschop]

So what were my RPMs the other day when I maxed out the NA 5th and the speedo hit 148mph on 285-30-18's?

[Dawgz83948]

It's doable @ 5700rpms.

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[xschop]

I thought that was conservative too as my speedo has become intermittent the last couple weeks (been yellin' gimme a break byatch) and taller tires throws the calcs off.

[Dawgz83948]

actually your tires are too small in diameter. 225 50 16's are 25". Yours are under 25" in diameter.

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[Porch]

Here's a good online calculator!
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[xschop]

So what RPM will the Turbo Trans with NA 5th be on my tires at 70mph where I am suppose to commute as a law abiding citizen?

[docwyte]

Dude, I'm going to rev mine to 11!

hehe. I'll probably stick to 6500 rpm with my motor. Cam is supposed to give a power band to 6400...

[Porch]

Go measure your tires, xschop! Measure from the center of the wheel to the ground, then multiply by 2.

[Dawgz83948]

Or he could measure the whole wheel and multiply by 1.

[944-LT1]

Nope. Measure the whole wheel and divide by 1.

[xschop]

The largest caliper I have is 24" lol

Didn't Dawg just post that my tires are 24.84"?
I'm curious what the RPM drop will be at 70mph turbo trans with the NA 5th swap. Would be nice to see a solid 32mpg's out of this 5.3

[Porch]

Re: Measuring the tires... You're supposed to measure from the center to the ground because tires compress under the weight of the car.

For example, a wheel may be 24" diameter without a load on it (12" radius). With the car's weight on it, maybe it drops down to 11.5" radius--which is like having a 23" diameter wheel. Makes a difference

[944-LT1]

I was just havin' fun with ya.

[Dawgz83948]

Me too, but I already posted the tire diameter anyway so it's a moot point.

[Porch]

LOL, just checkin