Thread: engine harshness at high revs
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Old 07-06-2009, 12:03 PM   #42 (permalink)
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Quote:
Originally Posted by turbo8765 View Post
It's largely an inherent property of the engine. A V6 is not inherently balanced. Neither is an inline 4 cyl, a boxer 4 cyl is.

Straight 6 cyl and 90 degree v8s are inherently balanced also. That's partly why BMW uses straight sixes and refers to a V6 as a bent six.

When u take a motor that's not inherently balanced and give it large pistons and a long stroke (high velocity), it's going to vibrate a lot. You must then add counter weights to smooth things out, but that robs power and increases complexity. They can be made smooth ie NSX, but it's not easy.

I have an M3 and a 335, and they're smoth as silk. Coming from that, the VQ37 feels VERY harsh.

You can't compare the vq37 to the v8 because the v8 is an inherently balanced configuration.

I could explain in much more detail, but I'm typing on my iPhone
That was my theory, but the V8 "version" of our engine is also rough in the high revs. That's what my post pointed to, but it's got to be something else or the VK50 would be smooth and apparently it's not.
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