M30 Turbo engine build

[Good & Tight]

My intent was to run stock main bolts but when initial torque down didn't feel right I pulled them out to find this. streeeeeetch

[RagtopE30]

This is awesome! I am looking forward to watching this progress.

[Doughnut]

This is turning out to be a great thread with fantastic information.

Keep us posted Otis

[ForcedFirebird]

Now they are all perfect..!

:)

most stuff is only hearsay like alot of performance products and so forth.

Yup. Dealing with this stuff for a living makes it necessity to have facts. Hard to argue with results.

[digger]

Always glad to help, Otis. :) Did the other John agree with a main cap hone? Seems like it's a hit/miss if there will be issues from going to ARP and NOT honing but never head of troubles with the bores corrected.



Not sure how gapless rings would create any more drag, as the side wall touching the cylinder wall is still the same thickness as a standard ring (same amount of ring touching). The ring doesn't have anymore tension on the walls than any other ring, either. They are gapless because there are 2 top rings, one with a groove to accept the secondary compression ring. When laid on top of each other with gaps facing opposite directions, they become gapless.



I could see where people have issues with second gapless rings and standard compression rings, like you said, if the piston was not gas ported, the top ring would be pushed up/out.

There is also argument that compression gapless are not as good as standard because they don't let enough gasses to pass through to push out the second ring - but many racers I know of use gapless top rings without issue. I am trying gapless tops in the Pink turbo car as well.

most stuff is only hearsay like alot of performance products and so forth.

[Good & Tight]

Always glad to help, Otis. :) Did the other John agree with a main cap hone? Seems like it's a hit/miss if there will be issues from going to ARP and NOT honing but never head of troubles with the bores corrected.
.

Yes, in fact a few were ever so slightly out of round. Now they are all perfect..!

[ForcedFirebird]

Always glad to help, Otis. :) Did the other John agree with a main cap hone? Seems like it's a hit/miss if there will be issues from going to ARP and NOT honing but never head of troubles with the bores corrected.

Never heard anyone respected recommend the gapless second, apparently it unseats the top ring due them to causing a higher pressure between the top and second ring (presumably due to better seal) which lifts the top ring a little more hurting ring seal. Many piston companies use an accumulator groove between top and second ring which is a reservoir so that any blow by the top ring cause lower pressure on the underside of the top ring which helps stop it flutter.

Most recommend the top be gapless if gapless are used and claim it better maintains the seal and shows lower leak down numbers when the engine has mileage on it. Could be better for reducing oil contamination which is good for E85

Others say there is nothing to be gained with gapless over a good conventional ring with torque plate hone and bed in process and the gapless wear out faster and better seal is overcome by higher friction (torque to spin short block by hand). Everyone has an opinion on it, those trying to sell you something are usually bias…..so who knows probably depends….

IMO you probably need to be running a vacuum pump and/or low tension rings of some kind to see any big difference between various rings and the torque plate and hone finish is more important so trust a competent machinist and GTG.

Not sure how gapless rings would create any more drag, as the side wall touching the cylinder wall is still the same thickness as a standard ring (same amount of ring touching). The ring doesn't have anymore tension on the walls than any other ring, either. They are gapless because there are 2 top rings, one with a groove to accept the secondary compression ring. When laid on top of each other with gaps facing opposite directions, they become gapless.



I could see where people have issues with second gapless rings and standard compression rings, like you said, if the piston was not gas ported, the top ring would be pushed up/out.

There is also argument that compression gapless are not as good as standard because they don't let enough gasses to pass through to push out the second ring - but many racers I know of use gapless top rings without issue. I am trying gapless tops in the Pink turbo car as well.

[bmw335isturbo]

I am at work and saw this!!!!
������ looks to be a good year.
The m90 I forgot when I get home I can look it up, I just figured some one might be able to help what year/ model did this block come out of?
Sorry to stomp on your thread. I like where you are going with this.
Ok I found it. Google��

[CorvallisBMW]

sub'd for m30 pr0n :)

[digger]

Otis, the total seal rings, is there a particular reason why you went with the top ring instead of the secondary ring? Is there any kind of particular benefit in chosing the top ring over the secondary ring, when using those total seal rings?

Otis, the total seal rings, is there a particular reason why you went with the top ring instead of the secondary ring? Is there any kind of particular benefit in chosing the top ring over the secondary ring, when using those total seal rings?

Never heard anyone respected recommend the gapless second, apparently it unseats the top ring due them to causing a higher pressure between the top and second ring (presumably due to better seal) which lifts the top ring a little more hurting ring seal. Many piston companies use an accumulator groove between top and second ring which is a reservoir so that any blow by the top ring cause lower pressure on the underside of the top ring which helps stop it flutter.

Most recommend the top be gapless if gapless are used and claim it better maintains the seal and shows lower leak down numbers when the engine has mileage on it. Could be better for reducing oil contamination which is good for E85

Others say there is nothing to be gained with gapless over a good conventional ring with torque plate hone and bed in process and the gapless wear out faster and better seal is overcome by higher friction (torque to spin short block by hand). Everyone has an opinion on it, those trying to sell you something are usually bias…..so who knows probably depends….

IMO you probably need to be running a vacuum pump and/or low tension rings of some kind to see any big difference between various rings and the torque plate and hone finish is more important so trust a competent machinist and GTG.

[LowR3V'in]

What power did you end up making on the junkyard build?

[Cronopoulos]

This is dope!

[ThatOneEuroE30]

This will be good

[Red88]

Can't wait!

[Good & Tight]

whats your opinion on the "race" bearings? worth the extra money? I'm still deciding between OEM of those for my build.

Never used race bearings they don't add HP. IMO OEM bearings last for 300k+ so I don't see the added benefit for race one's. That's my take on it.

It's more critical to have the correct clearance's on the rotating assembly, main & rod bearings.

Otis, the total seal rings, is there a particular reason why you went with the top ring instead of the secondary ring? Is there any kind of particular benefit in chosing the top ring over the secondary ring, when using those total seal rings?

This will be the first time using gapless top, always used gapless secondary one's. Lets see what happens..!


grsmonkey= I have to check the compression, ordered this combo 5 years ago so I don't remember.