Crankcase Evacuation System for a street car....

[67coronetman]

I am getting ready to run a Crankcase evacuation system on my street car i read where it could junk up your mufflers how many out here run it and has it caused you any issues so far...

:headbang::headbang::headbang::hello2::hello2::hello2::hello2:

 

[snakeoil24]

Not really mean't for street use. Why would you want it? Also will put heavy wear and tear on Rings.

 

[sleepar]

If you drive full throttle a quarter mile at a time you will be ok.... after about a 1000 miles the rings will be done..... seen it on a 600 hp 305 in a monza.... he was warned but found out when he lost 1/2 his compression

 

[383man]

My setup is not the evac system as I have hoses on my breathers but they just go down under the car and vent to atmosphere. It works good on my street car and I only put the hoses on so that it would not blow any oil out on the valve covers when racing but it never has any oil drip from the hoses. The evac system wont work good anyway when you run a full exh system like I do. Ron

 

[Mr Belvedere 30144]

Meant for hi compression race engines and will ruin a street engine is short order. Why would you even consider doing this?

 

[67coronetman]

Interesting replies it never hurts to ask as i was wondering if & how it would be good or bad so now i am thinking maybe it would be better not to do it... Unless it will work i am just asking..

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[Hemirunner]

Now, I just have to ask you experts, just how exactly, will adding pan evacs to a street driven engine will ruin it?

 

[67 B-body]

How is it different than using a good PCV system?
Just asking for specifics here......

 

[Mr Belvedere 30144]

For an evac system to function well and be of any help the engine must be sealed well. A screw in dip stick and no pcv or breathers is recommended. The oil pulled from the crank case usually dumps into the exhaust so smoke will be present in the exhaust. The oil level must be watched closely as you will slowly deplete your oil level. The oil required to lube your rings will be pulled out causing premature wear. It is a lot of work for little gain on a street engine. This is really meant for 14:1 and up compression engines as it will always have more blow by than stock compression ratios. In a race engine 30hp gains are common with an evac system.

 

[Hemirunner]

How is it different than using a good PCV system?
Just asking for specifics here......

A good PCV system on a high performance car will just allow oil to get in the charge which leads to detonation which is NOT YOUR FRIEND.

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For an evac system to function well and be of any help the engine must be sealed well. A screw in dip stick and no pcv or breathers is recommended. The oil pulled from the crank case usually dumps into the exhaust so smoke will be present in the exhaust. The oil level must be watched closely as you will slowly deplete your oil level. The oil required to lube your rings will be pulled out causing premature wear. It is a lot of work for little gain on a street engine. This is really meant for 14:1 and up compression engines as it will always have more blow by than stock compression ratios. In a race engine 30hp gains are common with an evac system.

This is a lot of mis information in one place. I have run header evacs and vac pumps on the street without using a screw in dipstick of any sort. Watching your oil level is basic maintenance 101 on any engine. A header evac will NOT pull enough vacuum to pull oil off of anything. Poor evac installation location or lack of a baffle is usually the cause of pulling oil out of the engine and into the exhaust. A vacuum pump should not be used on an engine with tight clearances and is typically not used on a street car. However, when you put a nearly 600 cubic inch engine and run it down the highway for hours at a time, adding a GZ vac pump built for street use can keep the blow by to a minimum. Just because there is vacuum present in the crankcase doesn't mean that oil can't get splashed on the cylinder walls to lubricate the rings. You guys should base your judgement on your own experience rather than relying on the internet or the local expert. You'll learn more. If you've got a hot BB mopar stroker on the street, I'd rather run header evacs that a PCV so you aren't sucking oil into the combustion charge. And evacs are way nicer on your rings than just breathers. All that air built up underneath the piston causes ring flutter. That's why a vac pump on any engine will ALWAYS make more power than without it.

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The evac system wont work good anyway when you run a full exh system like I do. Ron

This is the main reason NOT to run header evacs on a street car. It will just put pressure into the crankcase. If you run a high flow, performance exhaust setup with a straight flow through muffler, you'll be fine. If your run a muffler with any direction changes in it, you'd be better off with a setup like this. Ron has a very nice setup for a performance street car. If it's a restored type stocker, stick to PCV.

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And for the record, in a big cammed, big inch stroker, I always lock out the timing on the street. They run far better!! LOL

 

[Mr Belvedere 30144]

Unless you are racing and need a few tenths more etc It is a lot of unnecessary work and expense for little to no gain in a regular street car and is not needed as it is in a high compression race engine. Hey but what ever blow your skirt up. JMHO

 

[Hemirunner]

Unless you are racing and need a few tenths more etc It is a lot of unnecessary work and expense for little to no gain in a regular street car and is not needed as it is in a high compression race engine. Hey but what ever blow your skirt up. JMHO

I would agree 100% with this. I'm just wanting to point out that it's not going to ruin your engine just because you do it. Could it? Yes, if you throw them on with a restrictive exhaust, it will do it by filling the crankcase with corrosive exhaust gases rather than evacuating the crankcase pressure. Will it suck the oil off the walls or out of the pin bores? Not likely. Could a vac pump do this? Sure it could if you have tight pin bores or stock style components. It won't if you build the engine to work with it. A lot of people read these forums and just don't fully understand the what's and why's of all the things going on in an engine. Putting out blanket statements without an explanation just adds to the confusion.

 

[ykf7b0]

Interesting comments. I have had a crankcase evac system on my 10.15 compression street/strip car for 13 years now with no problems. I can't verify if it hurts or helps e.t.'s because I have only ran my car with the system.

 

[sleepar]

Now that is settled..... run a pvc valve in both valve covers teed into each other and use a single push on breather off the oil fill tube

 

[Hemirunner]

Now that is settled..... run a pvc valve in both valve covers teed into each other and use a single push on breather off the oil fill tube

That's the conclusion that you got out of this thread??? LOL If so, then all we did is just muddy up the water!!

 

[sleepar]

Pvc and evacuation are similar in theory the big difference is pvc draws a max of say 25hg that doesn't pull a vacuum in the block. Just removes blow by gasses where the evacuation draws a mutch greater vacuum enough to create a negative pressure... if you build the motor from the start that way and its tight it will last street/ strip /off shore etc... but it would be wasteful to take a healthy street motor and strip it down and rebuild over for evacuation street use.... but to each their own...

 

[67coronetman]

I was not trying to cause a fire storm i was just asking a question cause i have friends that run them & some that don't and i have never heard any of them say not to at this point... That have them on there cars.

 

[383man]

The best I can say is just be aware that with a street car and a full exh system the evac system with the check valves in the collectors may not be your friend and may cause more hassle then its worth. If your friends have got away with it they must run a very free flowing exh and thats good if it works for them. Myself I am happy with just breathers on mine as its worked good for me. My old 440 combo that had the MP .557 cam had a PCV in it that I used and it worked OK. But since I use a bigger cam and less vacum in this eng and I figure when I race at wide open throttle a PCV vlave wont be working anyway as you have no vacum at wide open throttle so I figured I would be better anyway with breathers on both valve covers as it will vent more crankcase pressure when racing then if I had a PCV valve system on it. And as I said I just put the hoses on the vent the crankcase fumes down low as I was afraid when racing the breathers might get oil on my valve covers but I have seen no oil in the hoses I put on and its had no eng oil leaks. Ron

 

[67 B-body]

PCV.... NOT PVC......

There is no way in hell, that the cyl walls will lack lubricant with any type of EVAC system brought up in this thread....
Oil on the cyl wall is placed there by the crankshaft slinging it.... What kind of vacuum will suck oil off the cyl walls???? You could hook a 2.5hp shop vac up to your valve cover and not suck the oil off of your cyl walls....
Also,,, all of the systems that hook to the headers SHOULD have a check valve to prevent exhaust gasses from pressurizing the crankcase......

 

[kidmopar]

if u use the complete kit with the check valves and breathers on the front of valve covers with baffles theres no problems!! no oil comes out or smokes if its done properly! if u follow instructions with the kit theres no issues however u must have a good exhaust system ,, i use it because its cheap horsepower!!!

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the real trick is the check valves,, if its working right u can pull the hose off the breather and it will suck like a pcv unit, if it blows exhaust out of the hose to the breather its bad thats why they recommend a very free flowing exhaust,, one guy i know who chimed in has gone 13 years with no problems!! its all in the details!!! a homemade unit is only as good if its copied after the real deal like the ones moroso or mr gasket offers.. i use the mr gasket unit. and keep the paper work it tells u what replacement valve to use if needed