Blackbirdws6

iTrader: (7)

I will try and keep the story short but perhaps some of the experts here can provide some insight into why this engine drinks oil. Here is the basic setup.

Procharged (~18-20lbs of boost) 383 LT1 - Callies Dragonslayer crank, compstar 5.7 rods, JE 2618 blower pistons, total seal gapless top rings. EFI 24x LS1 pcm conversion tuned by two reputable tuners. PCV alterations have included a RX Extreme Catch Can with a breather on the passenger valve cover/ Mighty Mouse PCV boosted catch can (no breathers, breathers on both valve covers, breathers on one valve cover). No change.

I built the original iteration and while it made decent power (700+rwhp) and lived for 3 years with routine beatings, it would drink a quart every 120-150 miles. Once built, the car was started to confirm no leaks and put on the dyno for tuning.

I got tired of the oil consumption and pulled the engine. Before doing so, I did a leak down test and it was clear the rings were not sealing. I dropped it off at Ellwein Engines since he has built many proven LT1's, including boosted setups. Everything was torn apart and after he got the block to the machinist, if was determined the prior machine shop did not bore the cylinder to 4.030 but 4.027. The bores were also slightly oval. Not good for a ring seal so we felt confident we found the smoking gun.

Here is the build link with images (click them for a large image) - http://www.ellweinengines.com/ERE48/ERE48.htm

Everything was brought back to spec, new total seal gapless rings, etc etc. Cylinder heads were gone through completely. I followed a strict break in procedure and beat on the engine pretty well to seat the rings. Unfortunately the oil consumption has come back the same as before.

The motor is back with the Karl Ellwein. Upon tear down with around 600 miles, the cylinders are like mirrors with no appearance of a crosshatch. The machine shop doesn't know why the engine is consuming oil or the rings didn't seat properly. This isn't their first rodeo machining a LT1 block for boost. I sent a piston with rings to Total Seal for inspection. The person I have been speaking with has been kind and very eager to help determine the issue. Unfortunately, they indicated nothing appeared out of order and rings show signs of seating.

So now with everything apart, the plan was to switch a few components around. New 5.85 rods, custom diamond coated pistons, bump compression a little bit and run a conventional set of total seal rings made to handle the boost. Before I spend any more money on this, I am looking for any and all insight on why this engine continues to burn oil.

Aside from the oil consumption and smoke out of the tail pipe, it has always run hard and hasn't given me any major issues.

WE TODD DID

iTrader: (2)

Over fueling the engine is washing the oil away from the cylinders. No oil means no lube. No lube means the rings are wearing the cylinders out.

Blackbirdws6

iTrader: (7)

Thanks for the input. The rational makes sense. How easy is it to wash down a cylinder? I monitor a/f with a wideband and the idle would be rich (IMO) at around 12.5. Heavy part throttle was too rich (high 10s) and WOT was around 11.5-11.8. I guess I may be answering my own question a bit and confirming your response but I was under the impression (perhaps the incorrect one) that it took a lot more fuel than that to wash down a cylinder?

WE TODD DID

iTrader: (2)

It really depends on a lot of factors. One of them being the hone job on the cylinders. On a nitrous or boosted application, you hone differently than a n/a application. You want the cylinder walls to hold more oil in your case. 10 or 11 anything on your afr is way too fat.

Shownomercy

iTrader: (1)

If we assume the two builds were completely different and no relation between the two, the only issue that reappears is the tune used on both. Which apparently, was a shitty one. I find it damn near impossible for you and Karl to make the exact same mistake if it was a mechanical issue to prevent ring seat properly.

When the second rebuild was at dyno for tune, was the tune tweaked at all? However that was after a few hundred miles of running around on the previous initial tune correct?

Blackbirdws6

iTrader: (7)

Good feedback. Thank you.

Since startup of the rebuild and through break-in, the original tune was used. The retune was done after I had already put ~600 miles on the engine. The tuner did what they could but without a clean running engine, it was likely an effort in futility (which I forced).

stevieturbo

Not quite clear about your crankcase breather system ?

It does have the ability to breathe ? and unrestricted ?

Add a pressure sensor or gauge and monitor crankcase pressure to see if it is excessive.

12.5 AFR at idle is very very rich, no need for that at all.

the fact the same problem is happening with 2 different engines....means it's more than likely nothing to do with the engine, and something bolted to it.

ie breathers, poor tuning as far as the very rich AFR's etc

You dont mention things like valve guides etc, although they'd need to be pretty bad to be pulling a lot of oil in.

Were there any signs of oil around the intake valves ?

Blackbirdws6

iTrader: (7)

Agreed on the AFR not being ideal in certain situations. Basically I've tried every possible breather solution so I don't think that's an issue. Ive used the catch cans designed for boosted systems and even tried ditching them and tossing breathers on the valve covers with the pcv vented to a can. Basically, this thing has been allowed to breath.

Heads looked great and the intake ports and valves were spotless when we took it apart the first time and this time. To be clear, this is the same engine. The first I assembled and ran for a few years. Figuring I did something wrong, I sent it to a reputable builder and had essentially the same result.

jimmyblue

iTrader: (11)

Well, I have no idea what's the norm for turbo oil consumption
but high cylinder pressure pushes a lot of blowby, and high RPM
makes you a nice oil fog up top, to be sucked out by PCV. But
is the oil ending up in the catch can, or elsewhere? That is one
"cut" for diagnostics.

Turbo oiling, is perhaps clearance there too large or pressure
too high, and losing it there?

Not sure how thigns are plumbed on LT1s, but what I've
seen on LS1s is that, at WOT, the "real" PCV system is out
of the picture, and valve cover air is drawn backward by
light vacuum in the intake tract / crankcase pressure and
you get a snail track from the PCV "inlet" port (which is
back-flowing) down the TB throat from all the sucked-in
oil fog. I put a catch-can there and none in the regular line
(using a plastic sump-style fuel filter).

Blackbirdws6

iTrader: (7)

I understand some blow-by is expected with larger ring gaps and boost. The original builds PCV system used a Rx Catch Can. One line went from the PCV port into the can and fresh air was drawn in from either the blower inlet or port to the intake. The lines had check valves to avoid boosted air from pushing back through the system. It would collect that nice brown mud but nothing ridiculous.

For the new build, I switched to a MightMouse PCV can. The can one inlet and outlet. The outlet going to the port in the intake has a check valve to avoid boost pressure backflow. A -10AN line ran from PCV port goes into the can. One of the valve covers has a breather for fresh air. In talking with my builder, he indicated the two other very high HP LT1 builds (over 1000hp) have the PCV port plugged and just a breather on each valve cover.

stevieturbo

Again, stick a pressure gauge and check pressure within the crankcase under load.

It will cost almost nothing to do, and at least give you an idea if there is a problem in that area

What oil did you bed the engine in with, and what oil is in it now ?

WE TODD DID

iTrader: (2)

I think you missed the part where he said his cylinder walls look like mirrors. That is your oil consumption. With no ring seal, there is going to be a ton of crankcase pressure. I don't believe his initial problem was the engine(s) themselves, but the tune that ended up killing the ring seal.

stevieturbo

Did he not say this happened with 2 engines ?

ie old one with bad bores, and new one with new pistons, new bore finish, rings etc ?

WE TODD DID

iTrader: (2)

Yep, but if it had the same shitty tune..... Mirrored cylinder walls are a tale tale sign of fuel wash.

Blackbirdws6

iTrader: (7)

The engine is out of the car so no chance of testing unfortunately. Initial build was broken in with the comp cams break in oil. This rebuild was Rotella straight 30.

I follow the logic, just still a bit amazed it was that bad to wash the cylinders.

JGalt

some ideas

- measure your crankcase pressure with a pressure gauge
- 10+ AFR under power is not going to washdown anything
- you can get great sealing and no excessive oil consumption under boost with even a crappy hand-hone job using a harbor freight hone and sloppy hand drill work, assuming the cylinder out of round is within spec

Were the ring gaps aligned properly?

Do all the cylinders look exactly the same as far as the immediate hone removal?

Do you have any problems with oil pressure? What if your oil pressure failed and killed the lube then that killed the hone job and now you have high oil consumption, can that be ruled out?

Blackbirdws6

iTrader: (7)

- ring gaps were aligned per the manufacturer spec
- all cylinders look the same. Some Pistons were a little dirtier than others
- oil pressure was always excellent. 60 psi cold, 35-40 hot idle and back up to 60+ at WOT. No fluttering either.

JGalt

is there ANYTHING that could have prevented the oil from getting to the cylinders? do you have absolute confirmation that oil is actually reaching the cylinder walls? The oil pressure gauge may show the oil manifold is pressurized but if something funny is going on there could be a blockage or a hole is too big or who knows what, and it doesnt reduce the overall oil pressure but it prevents the right amount of oil from getting to the wall.

If this happened after 30,000 miles then I'd say probably not. But since it happened twice after the engine was apart within a few hundred miles then "something funny" is definitely possible. Did they do anything that could have left particles or beads in the oil passages? Could the bearings be in backwards? How exactly are the cylinders lubricated in your setup and is there some way you can confirm all is well?

JGalt

Is it possible on this motor to have the rods backwards and therefore point squirter holes the wrong direction?

Ari G

iTrader: (25)

Might be a bad piston design as you have alot of stroke and then piston design gets critical with rock at BDC that will cause blowby and oil consumption

Are the pistons the same on both builds?

What hone job and rings are you using?