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bykr
New User
| Posts: 2
| Joined: 10/07
Posted: 10/24/07 08:48 PM
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Almost $400 spent on a breather system?Have you guys heard of a PCV system.I put one on my car that was having a problem similar to yours.A breather on one side, a pcv on the other a "T" and some hose.Maybe $15.And before you slam it for being a stock type system,check the mags for many 9 and 10 second cars using it!Myself included.Plus it's better for the enviroment And I love your mags homebuilt hotrod $20K or less focus!
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Posted: 11/20/07 05:20 PM
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I still need to address this on my Fairlane. Like you I've had good luck with a PCV system, but some cars need more in the form of a catch can system.
The PCV should work in my case since I have minimal blow by and it's really only at higher RPM.
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Falcon67
New User
| Posts: 44
| Joined: 04/07
Posted: 11/28/07 08:12 AM
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I ragged them on this in another spot here: Breath of Fresh Air $7500 motor and no though to venting. Really, now.
1967 Falcon 4 door - 351C 1970 Mustang coupe - 351C http://raceabilene.com/kelly/hotrod Owner built, owner abused.
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Posted: 11/29/07 11:20 PM
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PCV systems are for modestly powered cars. A high-horsepower application has significantly more crankcase pressure to vent--which is why race cars don't have them. There is usually significant oil aeration in the crankcase vapors--regardless of the actual amount of crankcase vapor being vented.
It has nothing to do with how well the ring seal is, and everything with avoiding (at all costs) aerated oil being introduced to the combustion process. Even a small amount of oil in combustion will lower the effective octane of the air/fuel charge, introducing detonation.
We're aware that a lot of people use PCV systems in high-powered cars. On balance, the engine damage resulting from oil detonation will actually cause more pollution in the long run.
If you want to use a PCV system really bad, go ahead. We're recommending you do otherwise on high-output engines because it will save your engine in the long run.
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Falcon67
New User
| Posts: 44
| Joined: 04/07
Posted: 11/30/07 09:23 AM
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My main point really was that you dropped big *** on a motor and nobody thought about or planned a breather system for the engine, which should be a given. I had the pieces for my chosen method in the parts pile with all the other engine stuff because it was part of package in my mind.
Maybe you didn't really mean for the article to convey that message, but that's the impression I came away from it with.
I agree that a high end engine needs a good, tunable evac system. Most of the lower budget race cars at our track run a header evac setup and the higher buck cars and dragsters all run a big $$$ pump and catch can. Dyno shows the pumps worth 20+HP, depending on the configuration. Some street/strip cars have both PCV and a pump, then plug the PCV and slip on the belt at the track.
The 351C-2V in the Mustang uses a PCV setup. It's not ideal, but it works. Teardown after 2000 rounds showed still good ring seal and no evidence of oil contaminating the combustion process. That engine will be converted to a header evac setup this winter. It spends a lot of time at full throttle and PCV (as you noted) doesn't work at full throttle. Unless you have a really small carb LOL.
1967 Falcon 4 door - 351C 1970 Mustang coupe - 351C http://raceabilene.com/kelly/hotrod Owner built, owner abused.
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Posted: 11/30/07 09:01 PM
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Like a lot of other people, I consider an evac system part of the accessory drive, not part of the engine build-up. I see very few (ok, I've seen none) engine build-ups in magazines with evac systems as part of that. On the engine dyno, it was just vented into the dyno cell. In fact, we didn't even have a breather on it when we tested the 496 at Westech.
It would've been great if the engine only needed two breathers. Then it wouldn't have needed a breather system.
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Posted: 08/21/08 02:38 PM
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My only complaint is that you didn't let the oil drain back to the dipstick.
I was thinking of grabbing one of those dress-up dipsticks with the flexible sheaths, splicing in a tee, then connecting the petcock to the tee.
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