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That line is his only source of vacuum for the whole system. The best yet most simple setups I have seen had 2 or 3 lines going to the intake pipe.
Originally Posted by Atomic
With that filter he will never pull vacuum in the can, and under boost if there is a check valve in there he will be splitting blow-by between the filter and the front of the turbo which is exactly what you dont want to happen.
I would say oil in the intake has something to do with pinging at 5psi.
So if I delete the pcv system. Do a log for BBP he should see the pinging stop?
Can I just run both valve covers to the vented catch can and cap the vac source and fresh air source? I assume I would also need to change the check valve fitting to a regular one. I think deleting the pcv is my best bet for now especially if it gets rid of the pinging.
With that filter he will never pull vacuum in the can, and under boost if there is a check valve in there he will be splitting blow-by between the filter and the front of the turbo which is exactly what you dont want to happen.
I would say oil in the intake has something to do with pinging at 5psi.
The catch can is basically just a crude filter to catch the moisture of blow by. The 'filtered' air is now drawn back into the engine. I've seen it pulled with a pump, a fitting in the downpipe, or most commonly the intake pipe. Either way, you want a vacuum source on it to pull the blow-by out of the valve covers.
My setup is just like his without the filter on the can and a larger hose to the intake pipe. In the last 10000 miles I've drained the can twice and all my intake piping from the intake filter to the intake manifold are spotless.
From a thread on the DSM forum where the line from the intake pipe was measured:
During cruise (15-20% throttle) at highway speeds I saw a low of only -.6in/hg while the map was reading -5in/hg to -9in/hg
At 5psi, 23% throttle at the highway speeds the lowest I saw was -1.1in/hg.
At idle it's equal atmospheric pressure.
At WOT, 23-24psi of boost, I usually see a low of -5in/hg to -6in/hg.
40% throttle, highway speeds, 15psi of boost I see around -3in/hg to -4in/hg
Any turbo OEM car I know of doesn't have a catchcan setup and the inside of the intake piping is coated with blow-by, yet it functions fine. Properly or improperly setup, I don't see how it would affect OPs detonation. I think it's something unrelated, maybe too much ignition timing *shrug*.
Can I just run both valve covers to the vented catch can and cap the vac source and fresh air source? I assume I would also need to change the check valve fitting to a regular one. I think deleting the pcv is my best bet for now especially if it gets rid of the pinging.
What's the difference between that and just putting two breather caps directly on the valve covers? If anything that would just be more restriction for the blow-by and have an adverse affect IMO.
The catch can is basically just a crude filter to catch the moisture of blow by. The 'filtered' air is now drawn back into the engine. I've seen it pulled with a pump, a fitting in the downpipe, or most commonly the intake pipe. Either way, you want a vacuum source on it to pull the blow-by out of the valve covers.
My setup is just like his without the filter on the can and a larger hose to the intake pipe. In the last 10000 miles I've drained the can twice and all my intake piping from the intake filter to the intake manifold are spotless.
From a thread on the DSM forum where the line from the intake pipe was measured:
Any turbo OEM car I know of doesn't have a catchcan setup and the inside of the intake piping is coated with blow-by, yet it functions fine. Properly or improperly setup, I don't see how it would affect OPs detonation. I think it's something unrelated, maybe too much ignition timing *shrug*.
The LS engines are known to have a problem with oiling in the intake from the PCV system in stock form. Thats the reason even a lot of NA guys use catch cans on these engines. Any oil that manages to make it to the combustion chamber will greatly increase the chances of detonation. Im not saying that is the OPs entire problem, but eliminating that risk is a good idea.
Breathers on both covers would work fine as well. Under boost there will be airflow out of the crankcase due to blow by. Most guys do the vent to atomsphere to prevent pushing seals, which the LS engines will do if you dont let the crankcase breathe. Trying to recirculate used air by using a vaccum source sure is a lot of trouble for very very little benefit. If someone is super hung up on that, then a vacuum pump is a much better idea anyway.
What's the difference between that and just putting two breather caps directly on the valve covers? If anything that would just be more restriction for the blow-by and have an adverse affect IMO.
The only purpose would be to catch the oil instead of dripping off the filters.
Your saying if I had a sealed can it would be working and hooked up correctly?
The LS engines are known to have a problem with oiling in the intake from the PCV system in stock form. Thats the reason even a lot of NA guys use catch cans on these engines. Any oil that manages to make it to the combustion chamber will greatly increase the chances of detonation. Im not saying that is the OPs entire problem, but eliminating that risk is a good idea.
Breathers on both covers would work fine as well. Under boost there will be airflow out of the crankcase due to blow by. Most guys do the vent to atomsphere to prevent pushing seals, which the LS engines will do if you dont let the crankcase breathe. Trying to recirculate used air by using a vaccum source sure is a lot of trouble for very very little benefit. If someone is super hung up on that, then a vacuum pump is a much better idea anyway.
My engine went bad at 49000 miles from consuming oil. It had consumed 3 quarts of oil with only 2500 miles since the last oil change. It was rebuilt under warranty. Hopefully this rebuilt engine I have now is not doing the same thing.
Trying to recirculate used air by using a vaccum source sure is a lot of trouble for very very little benefit. If someone is super hung up on that, then a vacuum pump is a much better idea anyway.
The vent to atmosphere is without question the ideal setup on a max effort build, but I still think a properly functioning sealed can is a vast improvement vs nothing at all. The vacuum draw setup is used on the majority of street turbo lsx from what I've seen. He would need to have a stupid amount of blowby for crankcase pressure to cause his detonation with the sealed can I would think?
Not sure how that can is plumbed. Just ensure that no air that has passed through the MAF is ever vented and that no air that has not passed through the MAF is drawn into the intake.
Looks like some funky stuff going on with your timing just cruising even when there is no knock.
Looks like I am using alot of oil. This is from the catch can. Doubt I have 500 miles since i installed it. Seems like alot also about a quart low on oil with 1500 miles since oil change.
Think this is my problem? Any thoughts on the cause?
Jun 25, 2016 | 12:42 PM
