building a 24v DOHC engine

[2002maniac]

:banstick

[lifeiskaos]

:banstick

worthless post much?

[lifeiskaos]

so much nonsense in this thread!



the cylinder wall spacing is exactly the same on all x5x motors. in fact, it's exactly the same as the M20 and M42. I really doubt there is a real difference in cylinder wall thickness, and even if there were, have you EVER heard of somebody blowing out a cylinder bore from boost? I've never heard of such a thing. Usually people end up with broken ring lands from too much advance, or burned valves from not enough, and head gaskets that push out because they used shitty bolts.

But blowing a hole through the side of the cylinder wall? That's never going to happen. Maybe if you throw a rod through the block, but that's likely from improper assembly or a $shift. If 1 mm less material (on the radius, for 2mm overall) makes the cylinder wall suddenly collapse, I don't think you'd want to use that particular engine for boost in the first place.

Boring it to 86mm isn't going to hurt it for boost if you use the right hardware. the S52 is already larger than that and they're fantastic for boost. Same damn block too, so you aren't going to suddenly punch through the walls because you did a measily 2mm overbore.

thanks for the post nando. from what i've read, the problem with boring out an m50/m52 to 85mm+ is that there wont be much headgasket between the cylinders. seems like it would be quite easy to pop at >1.0 bar of boost

[2002maniac]

This whole thread is worthless. If you were serious about this you would do the research yourself. Similar builds have been done on bfc. Search!

[lifeiskaos]

you have no reason to be posting in my thread unless you have knowledge and experience with said situation, and are willing to share in a constructive way, so please stop wasting your time and mine, and gtfo

thanks

[SpecM]

But blowing a hole through the side of the cylinder wall? That's never going to happen. Maybe if you throw a rod through the block, but that's likely from improper assembly or a $shift. If 1 mm less material (on the radius, for 2mm overall) makes the cylinder wall suddenly collapse, I don't think you'd want to use that particular engine for boost in the first place.

Boring it to 86mm isn't going to hurt it for boost if you use the right hardware. the S52 is already larger than that and they're fantastic for boost. Same damn block too, so you aren't going to suddenly punch through the walls because you did a measily 2mm overbore.

truth

[lifeiskaos]

bitches... :finger:

[jahnaboi]

Good start. Do it!

[e30serg]

You got some female dogs running around your yard?
:)

The reason you don't want to bore out the cylinders out too much is because they can flex when detonation happens and allow compression gases to blow-by the rings. This makes you lose some power and increases your crankcase pressure.

If you're going to bore it out, make sure you use a torque plate to mimic the stresses put on the block by the head bolts.

Good luck!

[nando]

a torque plate is a great idea - but if your engine is detonating, you're going to be losing power either way and likely damage something, so you shouldn't be driving around like that anyway.

but then this is r3v, home of putting random engine parts together with an off the shelf chip (if that) and hoping it doesn't blow up..

[z31maniac]

thanks for the post nando. from what i've read, the problem with boring out an m50/m52 to 85mm+ is that there wont be much headgasket between the cylinders. seems like it would be quite easy to pop at >1.0 bar of boost

Time to use our critical thinking cap kids. The bore spacing on all the motors talked about is the same, why would an m5x with an 86mm bore be any more likely to pop a headgasket than an s5x with an 86mm bore.

Did you actually read AND comprehend nando's post?

[lifeiskaos]

Time to use our critical thinking cap kids. The bore spacing on all the motors talked about is the same, why would an m5x with an 86mm bore be any more likely to pop a headgasket than an s5x with an 86mm bore.

Did you actually read AND comprehend nando's post?

why said anything about an s50? the point is im not going to bore it to 86mm, or anything like an s5* engine, and i dont know if a standard m52 headgasket is big enough for an 85mm bore. as of now im going to stick with the stock bottom end, get some s52 cams, and work from there

[nando]

why said anything about an s50?

I did, actually. same bore spacing, 91mm, on everything from the M20B20 to the S54B32.

[lifeiskaos]

I did, actually. same bore spacing, 91mm, on everything from the M20B20 to the S54B32.

right, but like i said, it's easier to blow a headgasket when there is less material between cylinders. did you guys read AND comprehend my post?

[nando]

at some point, sure, but it doesn't seem to be a problem for all the turbo M3 guys pushing 1000hp.