A few 2.7 i questions

[CorvallisBMW]

Can you use the 'e' rods (with custom pistons, of course), or just the 'i' rods when building this motor? Also, does a 283/283 cam require performance valve springs or would the normal 'i' springs be fine up to 7000rpm?

[MrK]

I used 'e' rods and custom pistons, so from first hand experience, I say yes you can. A 283/283 cam can be used with stock springs, if they're new. I wouldn't try to use them with 15+ year old springs.

[SpecM]

-BUT I would suggest useing longer (135mm vs 130) "i" rods. Better revability, better with the cam too.

[Mr Deagle]

In my build, im going to be using an e crank, with i rods. with custom pistons, and schrick 284 cam, schrick valves, and schrick springs

[nando]

284 is the highest duration you can run on stock springs (according to schrick)

but upgraded springs are certainly reccomended. Personally, I'm using new stock springs with a schrick 284/272 and it runs fine. I'm not sure if schrick springs would make any difference in power or not.

[Mr Deagle]

Lol, springs will definitely not make a difference in power, unless the m20 can make more power at higher rpms

[nando]

I meant if it was floating the valves, that HD springs would help. But I really don't know if it is or not.

[Mr Deagle]

new stock springs should be good to 6500 continuously, anything above that, and i would want something stronger. which is why i got the schrick springs. im thinking maybe 7500 rpm?

[nando]

my motor runs out of breath by 6500, so yeah. not much point in me going higher than that.

[CorvallisBMW]

new stock springs should be good to 6500 continuously, anything above that, and i would want something stronger. which is why i got the schrick springs. im thinking maybe 7500 rpm?

So no 7000rpm on new stock springs?

[nando]

So no 7000rpm on new stock springs?

you can probably get away with it, but it doesn't matter. you aren't going to make any useable power up there, so there's no reason to rev that high anyway.

[JGood]

ummm, if you race that's pretty useable, when you can avoid a shift mid corner.

[nando]

sure. but trying to rev to 7k in the hope of making more power isn't worth thinking about, unless you spend a lot of time on headwork..

[CorvallisBMW]

good to know.

[Mr Deagle]

sure. but trying to rev to 7k in the hope of making more power isn't worth thinking about, unless you spend a lot of time on headwork..

Or a proper cam, that has the profile designed for high rpm use