i need some thought's on piston set up in by b27

[KillaCam]

i am thinking of buying 11:1 pistons and running a stock 731 head on top.
what do you think. it will be a stock block and everything.
i'm not going to boost or anything on this engine

[nando]

make sure you run some sort of aftermarket cam, or you'll have detonation up the wazoo on pump gas.

also with said cam, check/cut valve reliefs.

[ForcedFirebird]

make sure you run some sort of aftermarket cam, or you'll have detonation up the wazoo on pump gas.

also with said cam, check/cut valve reliefs.

x2.

Stock cams are not known for overlap lol.

[lennon]

i would get an 885 head and pistons made for whatever rods/crank you're using (eta i assume) + the 885 head. it has bigger valves and dual valve springs already.

[KillaCam]

i would get an 885 head and pistons made for whatever rods/crank you're using (eta i assume) + the 885 head. it has bigger valves and dual valve springs already.

well i got a 731 head already for cheap cheaper than a 885 head and i ported and pollished it both sided and i'm going to runn all the 'i' stuff. I can get bigger valves and stuff and a after market cam but if i ran a aftermarket cam would i have valve clearence problems?

[5KWattson]

24v ftw

[KillaCam]

make sure you run some sort of aftermarket cam, or you'll have detonation up the wazoo on pump gas.

also with said cam, check/cut valve reliefs.

i don't know what denotation is and what do you mean by check/cut valve reliefs

[KillaCam]

24v ftw

i could go with 24v and i was thinking about it i found a 328is stick crashed for 400$$ but i didn't have $$$ or space

[5KWattson]

ahhh i wanna do a m52 turbo build

[nando]

24v ftw

thanks for your poignant and insightful post. Please share more of your wisdom with the forum.

[ForcedFirebird]

well i got a 731 head already for cheap cheaper than a 885 head and i ported and pollished it both sided and i'm going to runn all the 'i' stuff. I can get bigger valves and stuff and a after market cam but if i ran a aftermarket cam would i have valve clearence problems?

Junkyards don't know the difference between an "i" and "e" head, but if you swap the "i" springs and have the head drilled for the extra cam bearings, at least you will be able to rotate the motor higher - even though the 731 head runs out of steam after 5k RPM.

i don't know what denotation is and what do you mean by check/cut valve reliefs

Detonation is how a diesel operates. Instead of having a spark plug, they rely on compressing the fuel SO much that it will actually "self ignite" from the heat generated by the compressing of the air/fuel mixture. In the case of a gasoline engine, this is very bad because if this happens it means that it will be happening TOO early and forcing your piston down when it should be moving up - possibly damaging pistons, rods, rod bearings and in extreme cases, the crank.

i could go with 24v and i was thinking about it i found a 328is stick crashed for 400$$ but i didn't have $$$ or space

No offense, but if you are talking about putting custom pistons in your engine and are balking at $400, you have a long financial road ahead of you. I have been building engines of all kinds, makes and sizes, and it's not uncommon to spend $400 on the pistons alone, bearing packages alone, gaskets alone, machine work alone etc - never mind being able to re-build an engine with custom parts to boot for that kind of budget.

Maybe I should ask the same questions as I ask my customers at the shop, and on my site:

What's your budget? What parts you already have? What's your abilities/experience/tooling? What's your power goals?

[KillaCam]

ok so this is telling me i should just put the 731 head on with stock eta pistons. I was looking to buy early euro eta pistons for 150 bux there raised flat top 11:1. or should i go with seta dome pistons. I want to get the most power from stock stuff.

[lennon]

You need to do way more research and also pick up lots of basic engine knowledge before you attempt to do any of this work to your motor. How can you expect to be successful at putting together a custom engine if you don't even know what "valve reliefs" in pistons are, or any of the other stuff you're asking us? I actually know about this subject but I had to stop myself from even trying to explain it to you, because I'm pretty sure there's no point.

[briansjacobs]

11:1 compression on pump gas. Motor will last you a week. I was running 11:1 in my old 2.5 and would get detonation on 110 octane. It was not until I ran 110 octane that the motor was safe to run.

And you will spend the better part of $800-$1000 on the pistons.

[nando]

didn't you say that was with a stock cam though? that wouldn't surprise me. at 11:1 I'd be looking at a schrick 288 or even 304. you'd have to retard it a bit at peak torque but it should be great past 5000rpm.