building a 24v DOHC engine

[lifeiskaos]

ehh i should just start a new thread. plans have changed a bit. i had fun with the turbo m20, im thinking of trying to build a nice NA engine for now. s52 crank with 84mm bore yields 2.97L iirc so i'll reach my 3L goal no problem. s52 cams, and if i decide to turbo later, i'll get low comp pistons and possibly mls headgasket

[lifeiskaos]

but for srs bsns, is 413 the ecu i should be looking for to run an obd1 m52? will i need a chip?

[z31maniac]

You should be banned for your outright laziness in this endeavor.

[e30this]

but for srs bsns, is 413 the ecu i should be looking for to run an obd1 m52? will i need a chip?

The red lle 413 is non EWS and the silver lable is EWS.
From what I understand the 506 ECU is M3 specific.
I read it some place but dont quote me on it, it has been a while.

[lifeiskaos]

You should be banned for your outright laziness in this endeavor.

stay the fuck out of my threads

[Massive Lee]

stay the fuck out of my threads

The initial post is soooo funny. :giggle:

In fact, not just the initial post. I knew there was no meat around the bone.

[lifeiskaos]

after several hours of research and calculations today, i've seem to come up with a final plan. the numbers, work out to be perfect, almost too good to be true.

according to my calculations, using an 89.6mm crank from an m54b30 or an s52, stock m52 pistons, stock headgasket, stock bore, i'll get 2.97L, so my goal of 3L shall be done. now i also determined that if i use 130mm rods, which i happen to have laying around in the garage, i can lower the compression from 10.2:1 to 8.9:1, which will be very suitable for boosting. is it physically possible to use said crank, 130mm (eta) rods, and stock m52 pistons?

[nando]

physically? sure, but I don't see why you'd want to do that. the rod ratio is going to be very low leaving you with very high piston velocities and higher wear on the cylinder walls. Not to menition it's going to change the CR (piston will be .6mm lower in the deck) but not likely a full point. They are also really heavy.

why not use the M54 crank with it's rods and pistons?

[JGood]

Getting the correct CR is only part of the big picture. Is the rod ratio, squelch area, swirl effect, etc... all ideal with the parts you are throwing together? One thing that always had me curious with people mix and matching parts from various engines is the above questions. Sure, it fits, but is it worth it? You spend all that money to build an engine, when custom parts for a little more money (maybe less?) could net you much better results.

Not that your combo won't work well, because I have no idea, and it very well could work great. But you seem to be doing all kinds of calculations that aren't focused on other important aspects of a custom build.


Edit: Nando kinda beat me to it...

[lifeiskaos]

physically? sure, but I don't see why you'd want to do that. the rod ratio is going to be very low leaving you with very high piston velocities and higher wear on the cylinder walls. Not to menition it's going to change the CR (piston will be .6mm lower in the deck) but not likely a full point. They are also really heavy.

why not use the M54 crank with it's rods and pistons?

well that is what i'm not sure of. i know 1.45 rod ratio (130:89.6) isnt the greatest, but i really dont know enough to argue. if that's really a bad idea, then i suppose i'll get pistons. im just trying to work with what i have and what i know, neither of which adds up to a whole lot. the pistons will actually be 2.2mm lower than stock at TDC, which is required to lower the c/r, especially with the added stroke

[lifeiskaos]

Getting the correct CR is only part of the big picture. Is the rod ratio, squelch area, swirl effect, etc... all ideal with the parts you are throwing together? One thing that always had me curious with people mix and matching parts from various engines is the above questions. Sure, it fits, but is it worth it? You spend all that money to build an engine, when custom parts for a little more money (maybe less?) could net you much better results.

Not that your combo won't work well, because I have no idea, and it very well could work great. But you seem to be doing all kinds of calculations that aren't focused on other important aspects of a custom build.

no, i havent taken much of that into account at all. i'll do more research on that, but any insight is much appreciated

[JGood]

no, i havent taken much of that into account at all. i'll do more research on that, but any insight is much appreciated

I'm not the guy to go to. Hell I can't even spell right 'squelch' should = 'squish'. Or Quench area. Or something along those lines, I'm not an engine guy...

[lifeiskaos]

haha well thanks anyways

[JGood]

Here:

http://books.google.com/books?id=UtxI5gXM1yQC&pg=PA213&l

Start reading 8-)

[lifeiskaos]

thanks for the link