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Turbo this engine?
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- Posts: 336
- Joined: Feb 12, 2006 12:00 PM
- Location: Fort Fun Colorado
Turbo this engine?
I just got my leakdown test numbers back for my 216,000 mile m30b34 '88 535is.
18%, 14%, 10%, 14%, 20%, 12%
"Fair - leakage is from both valves and rings; rings more so on cyls # 1, 5, and 6"
I'm considering a TCD S1 set up running 8 - 10 psi. I'm not looking to drag race, but I do enjoy the driving schools and would like some more giddyup on the long straights.
What do you think? Would it last another 50K? I do have another block and head that I could rebuild in the meantime.
Thanks,
Andy
18%, 14%, 10%, 14%, 20%, 12%
"Fair - leakage is from both valves and rings; rings more so on cyls # 1, 5, and 6"
I'm considering a TCD S1 set up running 8 - 10 psi. I'm not looking to drag race, but I do enjoy the driving schools and would like some more giddyup on the long straights.
What do you think? Would it last another 50K? I do have another block and head that I could rebuild in the meantime.
Thanks,
Andy
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- Posts: 242
- Joined: Sep 02, 2007 5:16 PM
- Location: KANSAS
Leakdown past the rings is usually more even across all cylinders. Its odd to me that you would have significantly more on some cylinder than others if the rings were at fault.
Have the valves recently been adjusted? Its a WAG, as they usually affect compression, not leak down. But if you had some real tight ones that could be causing this.
Turbocharging this motor would result in significant amounts of blowby, should it be going past the rings. You would need an oil catch can for sure.
Does the engine use any oil?
Have the valves recently been adjusted? Its a WAG, as they usually affect compression, not leak down. But if you had some real tight ones that could be causing this.
Turbocharging this motor would result in significant amounts of blowby, should it be going past the rings. You would need an oil catch can for sure.
Does the engine use any oil?
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- Posts: 242
- Joined: Sep 02, 2007 5:16 PM
- Location: KANSAS
Compression is a dynamic test and leak down is static.superbeeblaze wrote:How would a leaking valve effect compression and not leakdown?
Has this motor been sitting any length of time or is it in a daily driver? How hard does it get driven?
Sometimes a good old "Italian tune up" is in order. I put a junkyard M20 in my racecar last year that would spew oil smoke the first weekend but it has completely gone away after being run hard.
Valve adjustment can affect one and not the other. Leakdown tests are performed at TDC on the compression stroke with compressed air, compression tests use valve timing to fill the cylinders. If you've got a tight valve it will drop compression as it hangs the valve open on the closing ramp of the cam. It might not be so tight that it hangs open all the time, which would affect both tests, but just a little tight or adjusted differently than the rest will affect compression tests and not leakdown.superbeeblaze wrote:How would a leaking valve effect compression and not leakdown?
I never said anything about a burned valve. Read the post.
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- Posts: 336
- Joined: Feb 12, 2006 12:00 PM
- Location: Fort Fun Colorado
Thanks for all the replys.
Superbeeblaze - I was sad when the numbers came back and yes I have another 535i to drive
Turbodan - I've had this car for ~ 130K miles and adjust the valves myself every 15K to .013 cold. The valves don't have to be adjusted much when I do it. They are due to be adjusted in another 5k miles. The engine uses about a quart every 3,000 (Mobil 1 15w-50) - not bad at all the leakdown results suprised me because the car drives/accelerates nicely. I have noticed a slight drop in mpg's though but my idle starts to hunt between 600 and 800 when warm so it could be a coolant temp sensor issue.
Skeen - I drive the car daily and I'm not hard on it 90% of the time, but it does see a couple of ~6,000 rpm shift points daily. I just did a hot soak with Seafoam and ran it hard prior to the test. The car also does at least one day of driving school a year.
If I was to turbo this tired engine, would I damage anything that would make a rebuild down the road more expensive? Is blowby directly related to boost pressure?
Andy
Superbeeblaze - I was sad when the numbers came back and yes I have another 535i to drive
Turbodan - I've had this car for ~ 130K miles and adjust the valves myself every 15K to .013 cold. The valves don't have to be adjusted much when I do it. They are due to be adjusted in another 5k miles. The engine uses about a quart every 3,000 (Mobil 1 15w-50) - not bad at all the leakdown results suprised me because the car drives/accelerates nicely. I have noticed a slight drop in mpg's though but my idle starts to hunt between 600 and 800 when warm so it could be a coolant temp sensor issue.
Skeen - I drive the car daily and I'm not hard on it 90% of the time, but it does see a couple of ~6,000 rpm shift points daily. I just did a hot soak with Seafoam and ran it hard prior to the test. The car also does at least one day of driving school a year.
If I was to turbo this tired engine, would I damage anything that would make a rebuild down the road more expensive? Is blowby directly related to boost pressure?
Andy
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- Posts: 242
- Joined: Sep 02, 2007 5:16 PM
- Location: KANSAS
You could turbocharge it. Blowby is directly related to combustion chamber pressure, so it does increase with boost. It wont cause any damage though. Considering your oil consumption I would consider having the leak down test performed again at a different shop. It seems strange to me that a motor that uses so little oil is supposedly leaking down past the rings, and unevenly at that.andy535iyes wrote:Thanks for all the replys.
Superbeeblaze - I was sad when the numbers came back and yes I have another 535i to drive
Turbodan - I've had this car for ~ 130K miles and adjust the valves myself every 15K to .013 cold. The valves don't have to be adjusted much when I do it. They are due to be adjusted in another 5k miles. The engine uses about a quart every 3,000 (Mobil 1 15w-50) - not bad at all the leakdown results suprised me because the car drives/accelerates nicely. I have noticed a slight drop in mpg's though but my idle starts to hunt between 600 and 800 when warm so it could be a coolant temp sensor issue.
Skeen - I drive the car daily and I'm not hard on it 90% of the time, but it does see a couple of ~6,000 rpm shift points daily. I just did a hot soak with Seafoam and ran it hard prior to the test. The car also does at least one day of driving school a year.
If I was to turbo this tired engine, would I damage anything that would make a rebuild down the road more expensive? Is blowby directly related to boost pressure?
Andy
By all other indications, it sounds like you've got a good motor for a turbo. If I were you, I'd do it to it and see how it does. Its not going to hurt anything other than performance if its leaking past the rings or valves.
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- Posts: 336
- Joined: Feb 12, 2006 12:00 PM
- Location: Fort Fun Colorado
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+1 on that.
I had fun beating my worn out engine with a turbo on it. I got it tuned in with NO worries about frying it. Now that I am rebuilding, I feel much better that I won't have to go through the tuning process completely from scratch. Unless you really know what you are doing, I would get a base tune and work out all your bugs with a well broken in engine.
I had fun beating my worn out engine with a turbo on it. I got it tuned in with NO worries about frying it. Now that I am rebuilding, I feel much better that I won't have to go through the tuning process completely from scratch. Unless you really know what you are doing, I would get a base tune and work out all your bugs with a well broken in engine.
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- Posts: 336
- Joined: Feb 12, 2006 12:00 PM
- Location: Fort Fun Colorado