Generation IV External Engine - excessive oil consumption LS3 427 stroker??

Guys,

I have some issues with in my opinion extreme oil consumption in a LS3 block based 427 stroker with 4.065 bore and 4.1" stroke. This is a quite hefty street engine in a Corvette C5. It got all the goodies and has forged JE pistons with std. tension oil rings build by a very respected LSx engine builder over there and has been broken in well.

Still, it consumes about 1 quart per 300 miles of Valvoline VR1 20W50 so does not run any thin soup or so.

The PCV system and crankcase vent is all spot on and has a catch can, I can not see any mistakes in plumbing of the venting system either.

For the heck of I can't think of where the oil goes too:

something I checked:
-rocker arm bolts are sealed into ETP 255 head threads (new heads)
-catch can is not connected to FAST90 intake, has a breather on top.

PCV system is routed as follows: left and right valve covers into catch can, crankcase vent into catch can, catch can has a huge breather on top.

It might be imagination but I feel it might have quite high crankcase pressure.

what would you suggest to look at first?

Get the Pcv system and catch can off the car all together and get you a GZ vacuum pump. That has been the only thing to date to fix my oil consumption. When first built it was burning as much as yours and got better but still would burn oil until I put the vacuum pump on it. By far one of the better upgrades I have done. I am very happy with mine.

could you please send me a picture of your vacuum pump routing and setup?

if it helps I will definitely consider it before tearing engine apart and not finding anything wrong

well I can tell you I would not run all the lines to a catch can with a breather. I would get one of the RevXtreme cans and run it with the breather filter bonded to the oil fill cap like they sell it. Route the valve covers and crank case to the can and then a vacuum line off the manifold (just like stock was) to the can. As it sits now, i don't believe you are pulling anything out of the crank case by force (vacuum) you are just letting it all go out on its own.

Pics are at the bottom of page 1. Oil pressure issues were nothing.




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No doubt a vac pump will work but is that the cure or the problem?

No doubt a vac pump will work but is that the cure or the problem?


If you have any vacuum lines hooked up to the intake system you will burn oil. No matter if you have 15 inline filters it will get through. You need to get the oil away from the intake. If you have good compression and leak down checks good then your rings are good just need to eliminate the oil getting into the intake.

I agree on a unrestricted line between can and intake but a restricted (down to 1/8") line will keep the can from huffing at idle.

My point is if you are getting blow by then a pump will mask it, but the problem is the blow by. You should not need a pump.

I agree on a unrestricted line between can and intake but a restricted (down to 1/8") line will keep the can from huffing at idle.

My point is if you are getting blow by then a pump will mask it, but the problem is the blow by. You should not need a pump.


Agreed.

The increased stroke pull's the piston out the bottom of the cylinder more.

Feel free to call me direct & I can walk you through the right design & as long as you don't have a piston/ring issue I can solve your problem.

A vac pump if done correctly will work wonders as well, but not very practical for the street. :thumb:

Tracy

Feel free to call me direct & I can walk you through the right design & as long as you don't have a piston/ring issue I can solve your problem.

A vac pump if done correctly will work wonders as well, but not very practical for the street. :thumb:

Tracy



I know of 5 personally running the GZ kit on the street and hp ranges from 450 to 921 at the wheels with zero issues. Only issue we seen is with a procharger you need the katech tensioner due to the factory style tensioner will throw the belt but other than that we are running the stock setup.

I was initially thinking of the rings possibly being pre-maturely worn from an improper break in, but the thought of worn valve guides also entered into my mind as a possibility, however not likely. The PCV system should IMO be deleted and in turn replaced with breathers with a LS3 427ci. I'm sure you already know what kind of vacuum you are pulling at idle, let alone at wot with that ammount of internal volume! My 1987 Eldorado uses 1 quart every 200 miles and I know for a fact it's due to the rings. A compression test will tell you the story of how your rings have been doing.

and has forged JE pistons

Exactly what kind of pistons? If they are not made specifically for your long stroke (ie short skirt), you're out of luck. Had my own little experience with that thanks to Diamond lol

these are custom pistons made for this combo, but my mistake, they are Wiseco not JE. Don't have any further particulars from the spec sheet but they had an awful long delivery time for sure.

i've given in on my 383 and am about to change the block due to oil consumption, if i blast mine to the red line in third gear coast down to say 2K rpm, then hoof it again i get a plume of blue smoke, classic ring problem. I opened the rocker covers and have vented them to atmosphere, but it still does it, better but still has similar oil consumption to yours, how does yours behave if you do this? ( I have NEW heads also ).

does none of those things actually. It doesn't smell when kicking it, but without catch can does push out oil vapour through the breathers because these sheet metal valve covers have no baffles in them.

I've got a friend with the same problem with his LS2 stroker. The engine puts out no smoke, gets 26-27mpg on the highway, puts out good power and the bottom end has been bulletproof. Checked the intake and the runners for excessive oil, they look fine. The leakdown and compression tests were done by two shops, and the numbers were good.

It just likes to drink oil when driven hard. The engine has 10K miles on it and he's just going to keep beating it until something goes seriously wrong.

Good Info good to know :)

Is that 4.1" stroke on the stock sleeves? I'm gonna take a wild guess here and say that's your problem if your answer is yes...

I'm having the same trouble, 2 quarts of oil disappeared in less than 200 miles... None in catch can and can is not tied to the intake... So where is it going? Seems as thou the crank seal is dripping... Could the lack of PCV be causing oil to push out the crank seal a past the rings just not enough to notice?

the oil is being vaporized in the engine thru the inatke and u should see black soot in ur tailpipes and on the ground below ur tailpipes.

I bet it has something to do with your heads. My brand new 331 stroker used a quart every 500 miles and there was black soot on the floor around the tailpipes. when we pulled the heads they had alot of oil residue. heads were brand new TFS TW 205's.

we traced the problem to incorrect instructions from TFS on installing the heads and using the proper head bolt thread sealer. using that much oil there is something definetely wrong with ur motor.

There is black soot in the exhaust, but I'm a little confused as how to the oil is getting into the intake? It has a catch can. If I were burnig that much oil wouldn't it be smoking?

Have you checked to see if theres piston rock?

I've heard from a few people that the bigger cube strokers have that problem not sure if thats it getting between the rings that way? Are you noticing any detination?

No detonation, did a cylinder leak test with 3-10 percent across the board compression test with 190-210 across the board... I don't think there is piston rock, the engine sounds smoothe when cranking and no piston slap is noticeable

What intake are you running?
What intake manifold?
Do you have a catch can? If is it closed or does it have a breather?

pull the intake and VC's and look for excess oil residue in the intake and on the heads. if excess oil is on the heads, pull them and look for where the oil is being pulled to.

I guarantee u the oil is being vaporized in the intake and burned, and it cannot be seen.

It has a vented catch can, and there is no oil in the intake as u have already looked. To my knowledge you cant get oil in the intake if there is no PCV system... The valley and both vc are vented to the catch can

Been through this on a 427 I found out the rings where not gap correctly plus they where in the wrong position. The combust ring gaps where on top of each other, Super heated one side of the oil ring causin it to flatten out. Had to do a light hone done and new rings fix the issue.

Not saying this is wrong with yours. But a thought.

pull the intake and VC's and look for excess oil residue in the intake and on the heads. if excess oil is on the heads, pull them and look for where the oil is being pulled to.

I guarantee u the oil is being vaporized in the intake and burned, and it cannot be seen.

+1 thats what i would think. to OP, just wondering, how often do you check your catch can and how much oil do you drain from it?

I'd take a look at the spark plugs, they'll tell you if your burning excessive amounts of oil. IMO, your engine needs the vacuum created by connecting the PCV to the intake, otherwise the excessive crank pressure will find another way out through seal, gaskets, or rings. Usually running 2 catch-cans inline before the intake vacuum inlet will eliminate any oil in the intake;at least it does for me. :nod:

Had the same issue on a new 404 stroker as Outlawz Racing. Ran ever fricking vacuum hose and breather setup I found on forums and worked many suggestions with both Vengeance and Cartek. Thanks to each for the time working with me to resolve issue on an engine they didn't build. In the end, oil was going past the rings on one of the cylinders. I was also told to use 20/50 from the builder. You'll get a lot of opinions on that, but there are a lot of vendors that don't use this wt, even on a stroker, unless tracking a car.

A suggestion: Wash up car and then go out and do some accells, WOT, with engine decells to brake the engine vice using brakes. After a few of these, go back to your rear panel/fascia and run your finger along it to see if you detect any slippery oil. If you do, you will probably have to do a rering. BTW, my engine passed leak down, compression, and only blew smoke on one situation after 3200 miles. Noticed light, very light oil film on the rear of the car and wrote it off as some road gunk, till it happened 3 different times. Even checked underneath for bad main seals, but no dice.

I agree, it's best to find the root cause now to ensure you don't cause any additional damage. Wish you all the luck brah, I know the feeling after you get a new engine and it starts using oil.

Mike C sends :usa:

I have tried everything and I can't figure it out... The engine used 2 quarts in 200 miles, I changed the oil, 5.5 quarts. Drove about 100 easy commute miles and rechecked, good same level... Took the car to the track, made about 10 passes
over a 2 day period and was maybe 1/8-1/4 quart low.
That's when I killed the trans, so it's out for rebuild and I'm
going to install a gz pro pump when I get the trans straightened out, worst case scenario I paid a grand for 10-15hp... Still not bad bang for the buck... Thanks for the help men