m42/m44 hybrid into e30

[deekay]

ok, so my buddy working on my car while i'm deployed tells me engine has started making "worrisome noises"... this after i just dumped about $3k into a complete suspension rebuild and 5-lug swap. -sigh- he's hoping it's just the water pump or another ancillary, but in the interest of planning for the worst, i'm drawing up plans for "the best twin-cam four you can build with factory parts"-

i searched through enough threads to find out that the e36 m42 head will swap straight into the e30. people say the cams are effectively the same or near enough to make no difference, but they do come with thinner valve stems, and while it's out i can have him put in the VW lifters i've seen mentioned. so there's a little extra high-rpm happiness and flow. nothing huge, i understand, but if i'm going to put in a replacement i might as well use a slightly better one.

on the bottom-end side of things, what about using an m44 block for that extra .1l? my thinking is, again; if i'm going to be swapping in a new engine, why not go for the displacement bump. i know the later engines have a knock sensor and the e30 does not, but i'd think that just means i won't have anything from the harness to plug in there; so no worries. anything else i need to worry about?

just so i'm clear, i'm only talking about swapping in a new longblock; engine management, intake/exhaust manifolds; driven accessories all stay the same. since the tranny has to come out too i *may* use an e36 m42 tranny for it's 1:1 5th because i love short gearing and i can get the shift points a little bit higher with a markD chip.

all advice and comments are welcome.

[deekay]

ok, found more threads that for some reason didn't come up with my original "e30 m44" search.

looks like using the e30 manifolds/wiring/ecu and the e36 head will eliminate most of my headaches-

the following threads made clear that i'm gonna need to run a hack with the temp sensors:

http://www.m42club.com/forums/showthread.php?t=442
http://www.m42club.com/forums/showthread.php?t=3717

Looks like the temp sensor issue is impossible to sort as with 3 days of tweaking we cannot get a reliable signal to the gauge from the M44 Dual feed Sensor. The only sure way is to stick the original M42 sensor in the water pipe or thermostat housing.

however, it appears that swapping the original ECU temp sensor over to the M44 block is a go; you just need to splice the other one into a hose so the gauge cluster works as well.

everything else; as long as you have all the ancillaries (meaning, are replacing an M42 and not something else) to put onto your new hybrid motor, you should be fine; which is about what i expected.

sorry if i'm rehashing old data here, but maybe this'll help someone else hoping to use this specific combo of parts.

a couple of the threads i found mentioned "tuning the ECU for the new engine"- i can't see ~100cc more making a huge difference using what basically amounts to the same cam profiles and compression ratio; but if you're uber-paranoid about it, you can always go check the injector-upgrade thread for something incrementally larger.

now, wish me luck that i don't have to do this, because once this crusty old vert is sorted out i'd rather just get to work on the turbo setup