Cam and headwork

[z31maniac]

Worth it on an M20 with stock compression? How much can you up the compression from milling the head or is negligible?

[BMWLA]

raising the compression isnt hard to do but there are alot of other things to factor in.
Dan C was quite the wizard with porting m20 m30 and 42s in the 90s he may have the answeres. as far as caming goes it's pretty dependant on what you are willing to put up with for idle

[nando]

anything abouve a 272 isn't worth it with stock compression, a 284 or higher is best suited to 10:1. there are plenty of gains to be had with the M20 head, and there is a lot more in depth discussion about this topic on E30tech if you are interested. most of the gains come from porting the exhaust, reshaping the short side radius and bowl work.

[2002maniac]

Have you considered an M50 swap? :)

j/k I'd say go with a 272, but seriously, M50....

[nando]

Have you considered an M50 swap? :)

j/k I'd say go with a 272, but seriously, M50....

this is why asking M20 questions here is so fruitless

[Jesse30]

2002 maniac meant to say m52. you should think about an m52 swap. :D




seriously though, 272 camshaft, oversized exhaust valves, gasket matched ports should give you some decent gains. IMO anything more than that is a waste unless your playing with the internal of your m20 while your at it.

[nando]

oversized valves aren't worth it on a stock m20 bottom end either, you'll gain maybe 3-5% more flow rom +1mm valves vs 15-20% from good porting. This is even more true with a milder cam like the 272.

[Jesse30]

you can get a ~25% flow increase with porting and oversized valves. if the head is off and getting worked over then why not do it right?


same mentality as if your going to be in there doing your tb then you might want to consider doing the waterpump while your there.

[nando]

you can get a ~25% flow increase with porting and oversized valves. if the head is off and getting worked over then why not do it right?


same mentality as if your going to be in there doing your tb then you might want to consider doing the waterpump while your there.

yes but the point is that 5% gain is exponentially more expensive than the initial 20%. not the same mentality as a $40 waterpump at all.

[Jesse30]

yes but the point is that 5% gain is exponentially more expensive than the initial 20%. not the same mentality as a $40 waterpump at all.

haha you're right, :)

[BMWLA]

porting, cc ing etc done well is not cheap but there are some serious gains to be had it is worth it to some like me personally im a purist.

[Farbin Kaiber]

What the fuck is a Dan C?

[BMWLA]

What the fuck is a Dan C?

what is a good question the zen guy dan colegrove he use to do a lot of flow bench stuff

[Farbin Kaiber]

Oh, If you would have said DCColegrove, I'd have known right away.

[BMWLA]

Oh, If you would have said DCColegrove, I'd have known right away.

i wonder what the extra c is for?