M60B40 Heads on M62B44 Block

[CoreyZ]

I remember someone stating that both the b40 and b44 have flat top pistons that reach the top of the block. Assuming that the head gaskets are the same thickness, it should be pretty close to 11:1 comp on the frankenstein.

[sticksdaman]

^ you me and everyone else!

Come on spring!

[iamsam]

I am still eagerly awaiting some real world data and results. If this conversion DOES work, I would expect over 300 bhp.

[The Dark Side of Will]

Haha no need, I just like to "overthink" things sometimes I guess to be 100% sure etc.

Maybe this weekend I'll clean up the M62 head combustion chamber and fill both up with water and measure the difference :)

It's all that much talk until you throw down and have the chambers cc'd.
In addition to that, you'll need to take an accurate measurement of piston deck height and know head gasket thickenss.

Compression ratio is the ratio of (displaced volume + clearance volume)/(clearance volume)

Clearance volume consists of:

-piston deck volume (positive if piston is in the hole, negative if out of the hole)
-piston dome volume (negative if pop-up, positive if dish, zero if flat)
-head gasket volume (bore^2 * Pi * thickness of head gasket)
-chamber volume
-If you *really* want to get anal, include the crevice volume around the top ring land.

What are the bores in the two head gaskets?

[iamsam]

Yup, look at my build thread... there are pictures of the engine assembly. The valves are the same, the M60 has dual valve springs and slightly hotter cams, plus the dual row timing chain. Plus a 1 point boost in compression ratio, due to the smaller bore... should be peppy:D:D:D

Garey

reading through it now...

[bmwmech1]

So you effectively have a 4.4L OBD1 M60??

keep us updated, I eagerly await!!!

Also another question: Are there valve diameter differences between the B40 and B44 heads?

Yup, look at my build thread... there are pictures of the engine assembly. The valves are the same, the M60 has dual valve springs and slightly hotter cams, plus the dual row timing chain. Plus a 1 point boost in compression ratio, due to the smaller bore... should be peppy:D:D:D

Garey

[iamsam]

Yup, mine's already built and sitting in my E30, awaiting the first fire up! Done and done... Except for the ECU... Mark D'Sylva will be doing mine, once I get him some baseline numbers...

Garey

So you effectively have a 4.4L OBD1 M60??

keep us updated, I eagerly await!!!

Also another question: Are there valve diameter differences between the B40 and B44 heads?

[dnick]

ooo i like this thread...

[Jean]

^ exactly what Garey did :) I am just looking at the data since I didn't see any of it posted before.

[bmwmech1]

so..... Would it be relatively simple to build an OBD1 "M60B44" with an M62 block/crank/pistons, and M60B40 heads as well as M60B40 everything else?

As in, take an M60B40, remove block/rotating assembly, replace w/ block/rot assy from M62?

Could this be the new secret to making >300bhp NA motors for cheap??? Would the M60B40 ecu compensate for the differences?

Starting to get a boner...

Yup, mine's already built and sitting in my E30, awaiting the first fire up! Done and done... Except for the ECU... Mark D'Sylva will be doing mine, once I get him some baseline numbers...

Garey

[iamsam]

so..... Would it be relatively simple to build an OBD1 "M60B44" with an M62 block/crank/pistons, and M60B40 heads as well as M60B40 everything else?

As in, take an M60B40, remove block/rotating assembly, replace w/ block/rot assy from M62?

Could this be the new secret to making >300bhp NA motors for cheap??? Would the M60B40 ecu compensate for the differences?

Starting to get a boner...

[Jean]

Haha no need, I just like to "overthink" things sometimes I guess to be 100% sure etc.

Maybe this weekend I'll clean up the M62 head combustion chamber and fill both up with water and measure the difference :)

[dirty30]

I think the M60 forum needs to buy Jean a christmas present next year for sharing all his research with us. Nice thread!

[Jean]

Talked to a friend of mine to pick his brain, showed him both heads and gaskets. Said putting smaller combustion chamber heads on bigger blocks is nothing new
(honda guys have been doing this to get more hp) and will bump the compression ratio (need to measure and calculate ). 11 should still be fine on pump gas although may be worth looking into e85 .

[g3n0cid3]

Correct me if I am wrong but, at that compression ratio would a smog pump be needed to pass emissions?