Should I rebuild or get a used motor and lower compression

[Jim M3]

Well the hits just keep on coming. I found out today that my motor did get damaged from my supercharger coming apart. So now I face the dilema of rebuilding the motor and beefing it up or getting a used motor and replacing it.

I found a used motor with 28k on it for $3,800 with a tranny. I don't need a tranny or the wiring harness or cams, so that is a low cost options since they could be re sold.

The other advice I have heard from two people is bore the cylinders and put in some 87mm pistons. Get the tops ceramic coated and use some good forged rods. I was also advised to ceramic coat the exhaust valves and lower the compression slightly to 9.5 to 1.

I am looking for advice from people that have done engine builds and their suggestions.

On top of all this I probably also have to buy a new aftercooler as well since metal could be stuck in the core and could break loose with air pressure UHHH.

[BMWManiac]

BUILD IT....do it!!!

I think that would be THE final thing for you to do. I think you'll be happy in the long run and not regret it later.

[jmargo]

What damage was done to your motor ?

[gerry_miranda]

wow....cut the losses and get a car more suited to tracking that will require only minimal mods...I say you have hit the limits of your car with the power you want and its track use

[Shuasha]

You don't need rods, I think that most of the turbo guys are proof of that. Maybe forged pistons but even that might be overkill if you don't need them.

Also, why lower the compression if you were fine before? Wouldn't that drop your power levels?

[Jim M3]

The cylinder walls are damaged from the debris from the blower siezing. The motor didn't fail it was the blower breaking apart that caused the damage.

[Jean-Claude]

Instead of spending $2k on another aftercooler. Have a shop cut the top off then remove the core. Have a new one made and installed. Then have the top welded back on. You could probably have it done for $200.

You might be able to clean the original core out and not have to buy/build another one.

[jmargo]

With the core I would first cover the inlet with a fine mesh (like womens hose) and blow air or pour water through the outlet and check for shavings.

Its got to be salvageable.

[jandizzle]

hey, since u guys are talking about engine rebuilding. im thinking of rebuilding the engine for my 325, i want to get a M3 engine in it if its possible. i seriously have no idea how to start or where. can u guys give me a lil info, cuz i wanna do it ASAP. thanks

[jrhaile]

hey, since u guys are talking about engine rebuilding. im thinking of rebuilding the engine for my 325, i want to get a M3 engine in it if its possible. i seriously have no idea how to start or where. can u guys give me a lil info, cuz i wanna do it ASAP. thanks

is there a "shaking your head" smiley anywhere? If there was, I'd post it...

[Jean-Claude]

hey, since u guys are talking about engine rebuilding. im thinking of rebuilding the engine for my 325, i want to get a M3 engine in it if its possible. i seriously have no idea how to start or where. can u guys give me a lil info, cuz i wanna do it ASAP. thanks


http://forums.bimmerforums.com/forum/search.php?searchid=4413157

[chewysjetta]

i would possibly by the tranny and cams. That is if you gave me a sweet deal.

[jmargo]

i would possibly by the tranny and cams. That is if you gave me a sweet deal.

OK vultures, this isn't a parting out thread. No more asking for parts publicly. :nono

[Jim M3]

I decided on doing a rebuild. I am doing an overbore to 87mm and going with CP pistons at 10.5 to 1 ratio with a .80 cometic headgasket for a 10.3 to 1 ratio no additional boost. Same recipe as I had before with new CP pistons and more displacement. I also am redoing all of the bearings, new oil pump, new racing timing chain, oil pan baffles. should be a new motor with a fresh lease on life. I am also getting the aftercooler taken apart to get out the loose potential parts.

Now I wait for my pistons to come in.

[bimmeracer3]

Im still a noob, but wouldnt the engine be better with a VAC MLS .140 HG, cp pistons, eagle rods, VAC MLS .140, and ARP Head studs?
that should bring the engine around 8.9-1 im guessing.

[97m3john]

With a turbo maybe,but not supercharged.

[Jim M3]

The stock rods are fine at this HP, I have the ARP studs, and I don't want a bandaid head gasket. This is an SC build so the compression is fine at stock levels.

The only dilema is the wait VAC has 11 to 1 pistons in stock but I don't want to do the ultra thick headgasket to lower compression.

[gboezio]

Don't ceramic coat everything, heat retension increase knock, maybe ceramic coat the exhaust valve if anything, or use Na cooled valve and /or wider valve seats for heat transfer. Just make shure there is no red-hot edges/parts like hot spark plugs too hot ceramics, etc...

[carcrazed4life]

I say if the blower is gone, time for a T-Trim. If your doing a HG, maybe a slightly beifer one. But the build up of boost on a T-Trim will be more linear and quicker then a V2... at least from the math I've been doing running the same psi/pulley past 9psi.

Maybe I got it backerwards though :)

[Jim M3]

No T-trim for me I don't want to mess with this car or any experiments. This car will be fine once it is fixed and I am leaving it alone. No more power improvements just reliable built power.

It has plenty of power and will pick up some torque with the increased displacement. Then I will drive it and not worry about it breaking. I will also rebuild the blower every two years to be safe.

Believe me when I say grenading a blower is a VERY expensive proposition.

[M3Jokster]

The cylinder walls are damaged from the debris from the blower siezing. The motor didn't fail it was the blower breaking apart that caused the damage.

Jim,

from the time the blower seized to the time you shut your engine...how long was it? or how many miles did u drive with the seized blower?

How much debri would you say was in your manifold and aftercooler?

mine seized and i immediatly shut down the motor and figured out that the blower seized. :mad

after removing the blower, i can see some metal shavings..(micro size....very very fine debri) in the aftercooler and in the manifold...

very little in the manifold..more in the aftercooler..

i removed my after cooler and washed it out with a high pressure washer.

Hope my engine's ok...so far...900 miles...

[pbonsalb]

Buy a magnetic drain plug. Change your oil immediately and again in another 1000 miles.

Philip Bradley

[Jim M3]

The car stopped itself. The seize was catastrophic and instant. There was metal everywhere in my car and it went past the aftercooler. I just bought a magnetic drain plug as well. There was metal in the oil and it actually melted right in the cylinder walls. The spark plugs were trashed and got coated in aluminum sludge. It was very bad the cylinders walls had scoring and aluminum melted to the sides of the cylinders walls.

[gboezio]

The air is moving insanely fast time to shut the engine off is probably well under a second before the first shavings enters the engine, it's all a matter of luck, it could all go trough the exhaust and do almost nothing, but more likely...well you know the rest...

[bimmeracer3]

Today i was wondering if one of those green gizmos could of saved you engine?
Would anyone be able to answer this?

[marc1119]

Today i was wondering if one of those green gizmos could of saved you engine?
Would anyone be able to answer this?

The gizmo would have been "before" ..where the damaged happened..

The aftercooler tank (between the blower and t-body), would have been the only thing to save the engine, and it didn't.....