If you were rebuilding an M50 for 6.5 psi...

[Jon K]

This is "totally" hypothetical. But let's say you were pulling your M50 non vanos out of the car in the winter to rebuild it. You know you're going to do a headgasket (thicker, to drop compression). You're burning a oil, so you're thinking piston rings. What else would you replace while in there WITHIN REASON? We're not talking $999 forged JE pistons or new connecting rods etc. The motor is in great mechanical shape other than the burning of oil. It's a M50 non vanos so it's already got dual valve springs and good connect rods as well as 10.0:1 compression though I am probably going to go to ~9.5:1.

Budget is, let's say... $600 in parts. Labor is of no issue.

[winfred]

your oil may be due to worn valve guides, i think some of the early m50s had crap guides, it's worth a check

[winfred]

ps id think about head studs over the turd stock bolts for extra security

[Jon K]

ps id think about head studs over the turd stock bolts for extra security


Winfred I plan on ARP head studs.

[632 Regal]

valve guides and seals since your burnin oil goods. Piston rings perhaps if thats the cause...i still lead to guides and seals.

[ryan roopnarine]

about 2 yrs ago (2003) i was going to rebuild a regular m50. i made a long @ss laundry list of parts (bearings, rings, et cetera) and called them into bma. the best they could do was about 280 barebones plus shipping. it wouldn't be an exaggeration to say it would be a good bit more than that now (roughly 400 , maybe lower). $600 budget might be lowballing it a wee bit, especially if you are going to be thorough about doing right by your turbo setup.

[Jon K]

about 2 yrs ago (2003) i was going to rebuild a regular m50. i made a long @ss laundry list of parts (bearings, rings, et cetera) and called them into bma. the best they could do was about 280 barebones plus shipping. it wouldn't be an exaggeration to say it would be a good bit more than that now (roughly 400 , maybe lower). $600 budget might be lowballing it a wee bit, especially if you are going to be thorough about doing right by your turbo setup.


Considering it's an M50 non vanos, it's more of a tank than the TU was. Connecting rods are RIDICULOUSLY large. The block chambers are better walled. The double valve springs help it rev +7000k. My bearing should be fine, I am really only thinking of rings, arp head stud conversion, head gasket, oil pan gasket, going to weld the oil pan nut on, and maybe valve guides and seals but I am not sure that's where i am burning the oil.

@ Jeff and Winred:

Anything "WRONG" with burning oil? Yeah it sucks to have to top it off every so often. I am only making 6.5 psi supercharged. I am not going to get pyscho and start upping boost (since its pulley based, thats difficult). So would you think the motor should be ok for now as-is? Anything WRONG in just burning some oil? I've got a catchcan installed, I've caught about 1/2 ounce of oil in the intake tract in about 3 months. So blow-by isn't too bad i guess.

[niall]

Big end bearings, Main bearings, front
and rear main seal, oil pan gasket,

is this the sort of thing your talking about,
its all pretty cheap ?

[jjw]

Could be as simple as bad PCV valve cause the burning oil. How many miles is the engine?

[Anton CH.]

You didn't state your milage, so for a high milaged supercharged/turboed engine it may be an idea to consider a new oil pump since you are changing the pan gasket anyway.

[niall]

You didn't state your milage, so for a high milaged supercharged/turboed engine it may be an idea to consider a new oil pump since you are changing the pan gasket anyway.

yeah, or at least check the lash and clearances

[gibbp]

The first thing you should do even before pulling it is to run both a compression and leakdown test. This will give you some idea for any blowby issues and the cylinders it effects.

Frankly, with only $600 to spend I'd simply replace any obviously worn parts and instead for a higher head gasket have headwork done to unshroud the valves and cleanup the intake track. Depending on the amount of bowl work done, this will increase the size of the combustion chamber and lower your compression a bit.

Honestly, I wouldn't worry about running 6.5 psi of boost with 10:1 compression. It really isn't a problem. As long as you have the correct fueling and timing set that is a non-issue. BTDT

Gibb

[632 Regal]

the main issue with burning oil is it can cause detonation from lowering the octane level. It can also build up on the piston tops leading to more detonation, I still dont think your blowby issue is adequite with them small hoses.

[Jon K]

the main issue with burning oil is it can cause detonation from lowering the octane level. It can also build up on the piston tops leading to more detonation, I still dont think your blowby issue is adequite with them small hoses.


Jeff, what do you mean you do not think that the blowby is adquite with the small hoses? I am confused as to what you're talking about.

[632 Regal]

we discussed this a while back, I think with any type of boost you need a larger system to handle engine blowby. Your little "catch" can doesnt catch everything for one and its too small for my liking.

I dont want to ruffle any feathers about this, it's just my oppinion. We simply disagreed on it so I let it go.

[Jon K]

we discussed this a while back, I think with any type of boost you need a larger system to handle engine blowby. Your little "catch" can doesnt catch everything for one and its too small for my liking.

I dont want to ruffle any feathers about this, it's just my oppinion. We simply disagreed on it so I let it go.


Well thing is, every turbo/supercharger setup for an M50 (E36 obviously) uses the stock lines. This is not an added system to the car. I merely put a catch can in-line with 1/2" fuel line from the stock 1/2 or 3/8" fuel line for the crank case vent. So, I know the capacity of my container is small... but it's only got a half ounce in it in 3 months. It is a stock crank case ventilation line, which is left completely stock in AA and TT turbo kits and AA/Rennsport supercharger kits.