engine harshness at high revs

turbo8765 · 07-06-2009, 10:04 AM

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

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07-06-2009, 10:04 AM	#15 (permalink)
turbo8765 Base Member Join Date: Jun 2009 Location: Southeast Posts: 11 Drives: M3, considering 370z Rep Power: 16	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