Cam and headwork

[BMWLA]

ok thanks is their something about the rods too?

[Jesse30]

z31, your block can either be an early or late since your smack dab in the middle. only way i know how to check is to look at the bearings :)

[Jesse30]

there really isnt much difference in the bearings either. its more preference of the builder. one has 2 tangs i believe the other had 1. im also just waking up so my memory is kinda foggy.

[nando]

there really isnt much difference in the bearings either. its more preference of the builder. one has 2 tangs i believe the other had 1. im also just waking up so my memory is kinda foggy.

it's more than that. read my previous post. :p

as an aside, I have a brand new set of late bearings I don't need if anyone wants them. lol. I think they'll fit in an M50/S50 block too (same part # anyway)

[SpecM]

Any input on S52 vs M54B30 crank? They both have the same 89.6 stroke, correct? Are they the "same?" IE, same construction/weight, is one preferred over the other?

s52b32 and m54b30 cranks are 100% the same, even the same OEM part #

about the blocks: there is a difference in the early/late main bearings, but they are interchangeable (crank-wise) and no one has really proven that one is better than the other.

[nando]

about the blocks: there is a difference in the early/late main bearings, but they are interchangeable (crank-wise) and no one has really proven that one is better than the other.

no they are not. They won't fit in the other block unless you mutilate the tabs. Trust me, I found out the hard way (i think that mistake cost me about $75). And no, I don't have proof, but I'd much rather have the 360 degree thrust bearing than 180 degrees, especially since the M20 only has one.

[z31maniac]

z31, your block can either be an early or late since your smack dab in the middle. only way i know how to check is to look at the bearings :)

I would build up another block while still driving the car with the motor that's in it. It has less then 128k, barely broken in for an M20.

SpecM, thanks for info on the cranks.

[SpecM]

no they are not. They won't fit in the other block unless you mutilate the tabs. Trust me, I found out the hard way (i think that mistake cost me about $75). And no, I don't have proof, but I'd much rather have the 360 degree thrust bearing than 180 degrees, especially since the M20 only has one.

are you saying that the crankshaft from a '88e will not fit in an '85e block, or the other way around?

[z31maniac]

I thought he was saying the cranks are interchangeable, but the earlier blocks have a 360° thrust bearing vs 180°

[nando]

I thought he was saying the cranks are interchangeable, but the earlier blocks have a 360° thrust bearing vs 180°

this, and that the bearings are not interchangeable between blocks.

[z31maniac]

If you were going to build a big bad high comp stroked M20, what cam would you go after? A lopey idle is OK by me.

Can you go any higher than 11:1? I know once you go past 10:1, you can no longer have the valve reliefs incase of a TB failure, but I would up the TB maintenance interval on a high reving stroked M20.

[nando]

if it's still a mostly street car, maybe the schrick 288, or the catcams cam that digger is running (220whp on a dyno dynamics is damn impressive for an M20).

I don't think you can really go much higher than 11:1 on pump gas, and you'd need some crazy cam profile to go with it anyway.

[SpecM]

but they are interchangeable (crank-wise) and no one has really proven that one is better than the other.

that's what I meant ^

the cranks are interchangeable, but not the bearings

[z31maniac]

if it's still a mostly street car, maybe the schrick 288, or the catcams cam that digger is running (220whp on a dyno dynamics is damn impressive for an M20).

I don't think you can really go much higher than 11:1 on pump gas, and you'd need some crazy cam profile to go with it anyway.

A 220 whp M20 would be insane and EXACTLY what I want!

Although I would think a well planned and well built M20 should be able to hit 200whp, which would be more than enough to have some fun in.

[der affe]

there is no reason not to do head work on a stock motor if you have the time and or funds!

you are getting it all wrong. like DCColgrove said, it is tedious, time consuming and mind numbing to do, but it will yield you gains in ANY motor, from a ford taurus to a BMW. there are gains to be made.

if you have a bigger displacement motor the gains will be greater.
if you have better induction, the gains will be even greater.
if you have better exhaust the gains will be even greater.
if you have a higher lift longer duration cam the gains will be even greater.

if you have the whole package, you will have the GREATEST gains possible from you engine combo.

it isn't going to set you back in the seat, just doing the head work and a match ported manifold, but it is a good start. you can always swap that head to your "new" bigger motor when you get it done.

you may run into problems when you are trying to tune it though. head work will change the flow characteristics of the motor (that is what you are trying to improve) and you may discover that you have flat spots in the acceleration that were not there before.