Currently I am using venturi or slashcut tubes in my exhaust to create a vacuum for crankcase ventilation. I ran this setup last year and was not happy with the results. It did pull a decent vacuum but it was shooting alot of oil into the exhaust which resulted in alot of smoke. When the car was idleing it would randomly let out a cloud as oil entered the exhaust. I could put in a catch can to prevent this but I think I want to ditch the setup all together. This method is best used for car running a open header in nonturbo applications. The check valves are prone to failure when running in high temp turbo applications which could result in exhaust dumping straight into the crankcase.
To replace my setup I was thinking about going with a vacuum pump setup, specifically a electric vacuum pump for crankcase ventilation. This would remove the parasitic loss that occurs with a belt driven pump and would not require modification to fit it into the current drivebelt assembly. I think the only way I could run a belt driven assembly would be to remove the ac compressor.
I found some info on the net, specifically from dpecorvettes.com. Here is his setup
He listed all the benefits
Prevents oil leaks from seals and gaskets by eliminating crankcase pressure.
Reduces parasitic losses from pistons pumping against crankcase air.
Improves piston ring seal.
Increases HP and makes your engine last longer.
Eliminates your PCV system and the possibility of oil being sucked into your engine keeping your intake system and combustion chambers clean.
Eliminates the need for mechanical belt driven evacuation pump that robs some HP and needs rebuilding frequently.
Superior to valve cover breathers and exhaust path suction type pcv systems which contaminate your exhaust system and mufflers with oil.
Pump can be set up with the filtered crankcase exhaust routed to air filter housing instead of out to breather if desired for a closed loop system (emission friendly).
Fits in factory battery tray for easy access to engine. (Battery must be relocated to trunk or rear compartment).
Ideal for Turbo, Supercharged and high compression engines which create higher crankcase pressures at high RPM’s/Loads.
Creates 5 inches of vacuum in your crankcase with a very high CFM air flow when needed at high RPM’s, exhausting and filtering all blowby, while still maintaining its vacuum for ring seal.
The waste oil level is easily seen through sight hose and drained through a valve on the side of catch can. If any oil vapors pass the modified Catch can, they will be condensed and caught in the Air Dryer before reaching the pump to ensure long pump life.
Sooo now I just have to find the right pump which is not too easy. He used a M3 secondary air injection pump which seems to be the perfect fit. Also I need to find the boost switch to activate the pump when I hit boost.
I’m not familiar with how your motor works, but if you have PCVs and they are up to the task, why would you need to have extra ventilation? Why not just find a more temp-resistant or better flowing PCV system and re-route it so that it has less of a chance to pick up oil?
The parasitic loss elimination from your oil pump and “increase in HP” are going to be minimal I’d think from a system like this. But the rest of the positives are nice.
My stock PCVs (2 of them) pickup in places where they tend to suck up oil… it makes everything inside look like poop. And every time I track the car, I get clouds of oil smoke out the exhaust as I accelerate out of a turn. However there is a way to re-route them to stop this problem that I’m going to do in the spring.
The switch is called a Hobbs switch. they are adjustable, They close a circuit when your desired pressure is reached. They are kinda cool. Carnut knows where to get them locally, I don’t remember where we got them.
So LS1s have electric crankcase pumps? I heard cobras have them too but im not sure. I since found a switch and and the bmw pump, the setup will not cost much just some time to fab it correctly.
we have air pumps for emissions. pumps clean air from the exhaust. low volume however.
as soon as oil hits them they burn out. some people try it and “like” it. imo, it doens’t accomplish much.
imo, if you can’t fit a real belt driven pump, and you dont have a 100% full time 100% FREE FLOWING exhaust aka dumped headers or like 5inch unmuffled, just run a nice breather setup. you will always be compensating somewhere
Those BMW secondary air pumps are really expensive due to their role in the emmisions control and really a waste of money on anything that’s not a BMW. I’m sure there are other less expensive alternatives.
im just going by my own configurations. i haven’t really been to the point of blowing out the dip, but any more ring seal is a good thing. obviously im putting a lot of pressure in the wrong places with my kind of setup. same with poopra
yea, these motors suck as far as stock PCV setup. alot of things have been tried, from check valves upto this kind of rig. This is one of the few that has held up to larger turbos / more boost. IIRC the “fastest” guy (high 8s) runs something similar.
ive spent weeks and weeks last year pondering the best setup possible. (less belt pump)…i was about to use drag style venturi setup with a check valve. but that’d only work at the perfect spot before my OPEN cutout, with a SEALED case. so when the first variable is negatory, and the case is sealed, then where does the pressure release?
i def didnt want oil in places it shouldnt be. i tried a well baffled setup from my valve covers to my turbo inlet. hell ya it pulled some air. AND OIL. nawww
2 years ago i ran these same lines to a vented catch can. MESSY
this year i am running oil breathers on both covers i believe. hope it works. simple, cheap, HOPEFULLY clean
I think the big problems with the electric pumps, which was already stated, is the fact that they dont last in oil supposedly. You could fab up a air/oil separator to run before “it” which will definitely help. The other issue is how much vacuum can the electric pumps pull under high boost and high rpm, where the crankcase pressure would be the worst? You probably dont need much, maybee 5inhg, 10inhg max.
Ever try measureing how much vacuum your current setup can pull? Im always curious, since the slash cut tubes effectiveness can vary drastically with the angle and location in the exhaust path.
I started putting together a mechanical setup, but its been more or less permanently put on hold in lieu of actually having the car running and driving :-p. Any electric setup just seemed like it would either not perform great and/or not last. This is obviously not always true as there are some people that have had great results with electric pumps. :gotme:
Exactly…running an air/oil seperator before the pump should help, but the oil vapor may still kill it over time.
I can get exhaust check valves for anyone interested in going that route. I know they hold 35 psi (haven’t found their limit yet) and I’ve used them in extreme heat.
I’d like to see how the current setup on the Supra works after adding an air oil separator before the check valves.
Im not too comfortable with the check valves that I have, they are made for open header applications with low exhaust temps. I rather move to something that is failsafe.
This is a great example of a well thought out crankcase ventilation system. Any GM secondary air injection pump can be used and they are fairly easy to come by. Visit any junkyard and look for any 98-01 blazer or jimmy. It would be nice to see this made and enclosed in a box with just the fittings on the outside using bulkhead connectors.
I know alot of GM guys that have run this for years. When I worked in the dealers we used to get these pumps all the time for warranty repairs because GM wanted you to replace everything in the SAI system. The pumps still worked so guys used them. They saw 7" of vacuum on their small blocks from the dipstick tube.
