excessive oil consumption LS3 427 stroker??
05-26-2008, 05:09 PM
#1
Staging Lane
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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?
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?
05-26-2008, 08:07 PM
#2
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.
05-27-2008, 07:39 AM
#3
Staging Lane
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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
if it helps I will definitely consider it before tearing engine apart and not finding anything wrong
05-27-2008, 12:20 PM
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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.
05-27-2008, 07:53 PM
#7
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.
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05-27-2008, 08:01 PM
#8
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.
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.
05-30-2008, 07:46 PM
#12
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.
05-30-2008, 11:14 PM
#13
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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.
06-02-2008, 02:49 PM
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Staging Lane
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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.
06-02-2008, 03:24 PM
#16
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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 ).
06-02-2008, 03:35 PM
#17
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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.
06-13-2008, 11:40 PM
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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.
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.
