Doing a 731 head on Eta bottom end, cam question..

[MR 325]

Doing a port and polished 323i head on an Eta bottom end. Which camshaft would be better for my needs... M20B23 cam or M20B25 cam?

[blueapplesoda]

b23 cam is hotter than the b25 cam
b23 cam has more duration than the b25 cam
b23 cam has less lift than the b25 cam

[hotballs]

I'm running an i cam (b25) in my 731 head. The heads apparently been ported. It pulls to the top, it's not flat like I've read but I have nothing to compare it to.

If I had both laying in front of me I would try the b23 cam. Everyone says it's a "hot cam"

[MR 325]

Thanks guys, you rock.

[eta]

I beileve the above is right about the cam expect the lift. I far as I am aware the lift on the b23 and b25 cams is the same from the spec I have seen. I have not measured on so if blueapplesoda has then his info is good.

To put in perspective a UK owner of a 327i (a 731 head on a eta block) recently swapped the B25 cam he had in the head for the B23 cam. He did not lose any power but peak power was moved 500 rpm to the right of his dyno plot.

[jbshaw11]

outcome of 731 head

I'm about to pop on a 731 with 323i cam, 323i intake and TB. 325i headers and no cat to 325i muffler, mark d'sylva chip.

What kind of gains did you end up getting with your build?