: crankcase evacuation
Apr 5th, 00, 02:23 PM
i have asked this before but here goes again. does anybody run a racing style crankcase evacuation system (hose from breathers to header collectors) on their street/strip car?
355, SUPER T10 4 SPD
Apr 5th, 00, 03:17 PM
I know of a couple of guys that do, but I think more for the look than anything. If there is ANY back pressure at all in the exhaust system, it will not allow the system to function at all. Backpressure would actually push the crankcase fumes backwards, tending to pressurize the crankcase.
Just my opinion,
Advanced Automotive Machine
Apr 5th, 00, 06:35 PM
I have run a crankcase evac system on my last three Pro Street cars with great success. Never any problems or leaks. They were all run with mufflers and the valve was installed in the collector. Never any backpressure,as a matter of fact if you removed the breather hose with the engine running it was pulling about 8-12" of vacuum from the hose. I have heard many say not to run this set up on a street car but it has always worked for me..On my new car I am currently building I am going to run a vacuum pump instead,they pull better vacuum. Just adding my experiences..
Apr 5th, 00, 06:44 PM
I run an evacuation system on my 69 396SS camaro. Mine works good. If you stick your finger to the end of one of the hoses, you can really feel the suction. Alot of people say that it's overkill, but I like it.
Apr 6th, 00, 01:50 AM
I am running it on my 396 the engine builder told me it would help the valves and plugs run cleaner than through the carb
Apr 6th, 00, 03:32 AM
Just curious. What is its main function? Does it aid in engine coolingas well as block venting? Do you need to run a dual vent filler cap, one on each valve cover?
Apr 6th, 00, 07:06 AM
The main function of the cranckcase evac system is to promote ring seal and vent cranckcase pressure. Yes you should run a breather on each valve cove.. I have seen a couple of cars that only run a valve on one header collector and tee in the two breathers together to that valve,but not sure how effective it is. The kits are sold with two valves,pipes and breathers by Moroso and MR. Gasket...Or you can by the pieces individually, It is just a smog air valve from a late 70's early 80's GM car, a couple of pieces of pipe, and a pair of Mopar breathers..Hope this helped!!
Apr 6th, 00, 08:11 AM
Sure did her69. Thanks alot for the explanation on this. I had an idea but wasnt totlly sure.
Apr 6th, 00, 03:27 PM
thanks for the info everyone,now here is why i asked. iwas running a breather on one side and a pcv valve on the other, it kept spitting oil out the breather when i ran it hard, so i figured with the big cam i'm running, i probably wasn't pulling enough vacuum to make the pcv effective, so i thought why not replace the pcv valve with another breather, so i did. now i seem to be pushing oil out of intake gaskets and etc. i built the motor last summer, 12;1 compression,256 duration and 523 lift. so have decided now that maybe a crankcase evacuation system is what i need. any otherthoughts, anyone?
355, SUPER T10 4 SPD
Apr 6th, 00, 04:06 PM
just a tidbit - I have a crankcase evac system on a BB w/blower. I didnt have any other way to pull vacuum for the PCV (without a elec pump) and so elected this method. The one way valves we (Her69 and I ) welded into the collector are incapable of "negative pressure" and pressurizing the crankcase. The vacuum being pulled into the headers is strong enough at idle to pull your thumb over the 5/8" hose and form a very good seal. It has worked for me and I would do it again. As a note, the "pro-street" cars Her69 references he built were very serious street cars making high triple digit horsepower (or in the case of the Duster - 4 digit HP) and NO expense was spared in formulating a working engine combo. I just had to blow the horn because I know he wouldnt!!! Crankcase evac works when installed right.
Apr 9th, 00, 09:00 AM
Afriend of mine runs a 94 ford stang with 600 hp at the flexplate.He was pushing too much excess oil thru the intake valve.He had to switch to long tube headers and an evac system or to use a vacuum pump.I recently read about using a Moroso pump.After a couple of pulls on the dyno,the article claimed a hp gain of 40 hp,which chp claims is very possible.My friend needed an evac because the crankcase pressure was causing the intake to lift slightly causing the gasket to lift,thus causing a vacuum leak.
Apr 14th, 00, 05:45 PM
That type of system works wonders on a car without a restrictive exhaust system. You need to run Borla or an equally free flowing mufler.If not at high RPMs the the exhaust pressure will acually cause more crankase pressure.My 69 camaro with a 383 ran high 11s,but had a plug fowling problem on the street because of the pressure forcing oil and spent gasses past the rings.when I put the system on the car the plugs started burning cleaner.It also stoped some oil leaks.I was running flow masters at first but they were too restrictive.My problem was acually worse.switched to borla and the system worked perfectly.
Apr 16th, 00, 01:53 AM
Tell you what.
I´ve even had probs with the collector mounted ones pulling to hard!
Sucking oil right out of the motor!
Still run an AN 12 based system on ol´slo´.
Works like a charm.One way valves i use btw,are common Volvo pulse air ones.Works great.
482 cubes of fogger injected thunder in a 71 z.