driver84

Hello All-

I have a friend who had a beast of a motor installed in his 2007 Corvette coupe about 18 months ago.

Here are the specs on the motor:

GM LSX Block (455c.i.)
Callies 4.250 Forged Crankshaft
4.130 Diamond Pistons
Callies 6.100 Rods
ARP 2000 Rod Bolts
Race Main and Rod Bearings
Warhawk LSX 235cc Heads (Heads have been ported and polished)
Comp Cam 242/244 .620 114lsa
Comp R lifters
Comp Cam Chromemoly pushrods
Rollermaster timing chain
Melling Hi-Flo Oil Pump
MTI XCelerator Intake
Ported Fast 90mm
Ported TB
Kook’s 1 7/8” Long Tube Headers
3” Hi-Flo Catted Mid Section
Corsa Sport Exhaust (Quad Tips)
NGK TR6 Spark Plugs
MSD Plug Wires
Underdrive Pulley
160 Thermostat


He has had (and still has) a few gremlins to work out of the motor.

The one I am concerned with at the moment is that he tells me since he had the oil changed a month (~400) miles ago (doesn't get driven much), it has consumed a quart and a half of oil!
It doesn't seem to be leaking it (the motor is practically brand new and has less than 5K miles on it). I would really hope it isn't consuming it, but that will be determined later.

The oil has to be going somewhere. If it is an internal issue either the rings or valve stem seals aren't sealing, and I will perform a leak down test sooner or later to try and determine this.

The other possibility that crossed my mind is that maybe there is a PCV issue. Has anyone on here seen huge amounts of oil consumed due to this? Again, this is a custom-built LSX block.

Any other ideas?

redtan

iTrader: (5)

If there is no visual proof of external leaking, then it's obviously internal. If it's internal and that bad (1.5 quarts per 400 miles), then there will be very very obvious signs of either burning (blue smoke) or mixing in with coolant. Check his exhaust/engine bay for such smoke, and check his coolant for oil contamination. If these are clear, then it has to be an external leak somewhere that maybe is hard to see.

There's only 2 places it can go, and at that rate like I said there will be very clear signs of where it goes.

LS6427

iTrader: (2)

Thats a terribly long stroke for how short the cylinders are on the LSX iron block. If his builder didn't put the proper piston ring combo in there, its a build issue. Happens alot with long strokes. He shouldn;'t have gone more than 4.125". Preferably a 4.1". 4.0 is great.

.

peterock98

iTrader: (25)

Try using regular oil.If you using synthetic maybe it's making the rings unseat.

fleetmgr

Synthetic won't make seated rings magically unseat. It might prevent them from seating in the first place, though.

peterock98

iTrader: (25)

Same Difference

LS6427

iTrader: (2)

That engine is old.....the rings were seated in a couple miles after it first ran.

Unless they had it running pig rich right from the get go and "gas washed" the rings and they never seated properly. I know people that have screwed up their tunes and had just that issue. Had to rebuild it to fix the oil burning after just a month or two.

.

driver84

Apparently, the motor was never "broken in." Break-in oil, or even non-synthetic was never run to let the rings seat. In addition to that, the tune was recently changed after it was found the A/F ratio was running as rich as 8 or 9:1 in some instances ...This would explain the chugging at low rpm...The car has since been retuned.

Oh, another great find: the throttle plate has a hole drilled in it...As we all know that is the lazy man's way of tuning or you are no good at tuning in the first place...These are modern engines with electronic throttle bodies, people!

Did a compression test yesterday, and the numbers aren't bad. One of the cylinders (still has good pressure) had a good amount of oil on the spark plug, though...Weird

The intake manifold is full of oil, so here is my plan of action...

1) Get an FSM and verify the PCV hose routing and make sure the valve is operating properly (not gummed up)

2) Add a crank case breather and a catch can to help meter how much oil is coming through

3) Properly break in the engine, which should have been done in the first place.

Whaddya all think?

driver84

I forgot to address this, but as you have already realized this...

The motor is 4.250 x 4.130

FMX05

iTrader: (3)

Do some research on Catch can setups. Most of the catch can's you will find for LSX's don't work very well. I know of two or three people with big name brand setups with all lines ran correctly that still get a full quart of consumption that doesn't stop in the can every 2,000-3,000 miles. RevExtreme used to be a sponsor here and their setup works great. In all honesty you need a dual can setup on these cars to catch ALL of the oil.

driver84

The catch can is the least of my worries at the moment...A quart in a couple thousand miles wouldn't bother me, it's the 1-2 quarts in a tank of gas that I am worried about!

conkrete21

Ben, while the oil consumption is notibily high, the car is not burning 2 quarts of oil within one tank of fuel or every 200 miles.

driver84

Well, we aren't sure how many miles were put on the car after the oil change and before you got it back from the shop. We will get a better idea of how much it is consuming tomorrow.