CCV smokin'
Postmaster
Joined: Apr 2004
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From: Ellensburg, Washington
Originally Posted by ernesteugene
I'd sure like to see your CC pressure measurements to support your claim, because based on both measurements and analysis I don't think your claim is possible!
I used my CC pressure gauge to measure the CC pressure in two trucks with your suggested setup. I took measurements on both trucks at idle conditions and revving the engine with no load, and one truck during a WOT dyno run. Even at idle their CC pressure exceeded the 4" H20 Racor recommended maximum, which is also a Ford CC spec. At WOT the CC pressure went to about 27" H2O, or almost X7 higher than the maximum safe level.
This pic might help explain why connecting your CCV hose to the tailpipe causes a positive (above ambient) pressure in your CC and not a below ambient pressure like you claim. First, the setup you describe isn't a Venturi, but even if you wanted to insert an actual Venturi into your tailpipe like the one in the pic, that wouldn't work either!
The pressure difference shown in the pic is between the lower pressure in the Venturi section and the higher pressure in the upstream flow region of the pipe. For a carburetor application the upstream pressure is ambient and the fuel bowl is at ambient, and the slightly lower pressure developed in the Venturi sucks the fuel from the bowel.
In your tailpipe the upstream pressure is higher than ambient and it increases for higher engine loads, and your CC should never be allowed to go higher than 4" H2O above ambient. Since 1 psi = 27.68" H2O, if the upstream pressure in the tailpipe is a typical 1 psi, the Venturi would have to develop a differential pressure in excess of 28" H20 to provide a vacuum to the CC. I can supply more details of my analysis involving tailpipe pressure vs exhaust flow velocity vs Venturi pressure if needed, but no one would want to clog up their exhaust flow with a Venturi anyway, so I don't think there'd be much reason for giving it.
I used my CC pressure gauge to measure the CC pressure in two trucks with your suggested setup. I took measurements on both trucks at idle conditions and revving the engine with no load, and one truck during a WOT dyno run. Even at idle their CC pressure exceeded the 4" H20 Racor recommended maximum, which is also a Ford CC spec. At WOT the CC pressure went to about 27" H2O, or almost X7 higher than the maximum safe level.
This pic might help explain why connecting your CCV hose to the tailpipe causes a positive (above ambient) pressure in your CC and not a below ambient pressure like you claim. First, the setup you describe isn't a Venturi, but even if you wanted to insert an actual Venturi into your tailpipe like the one in the pic, that wouldn't work either!
The pressure difference shown in the pic is between the lower pressure in the Venturi section and the higher pressure in the upstream flow region of the pipe. For a carburetor application the upstream pressure is ambient and the fuel bowl is at ambient, and the slightly lower pressure developed in the Venturi sucks the fuel from the bowel.
In your tailpipe the upstream pressure is higher than ambient and it increases for higher engine loads, and your CC should never be allowed to go higher than 4" H2O above ambient. Since 1 psi = 27.68" H2O, if the upstream pressure in the tailpipe is a typical 1 psi, the Venturi would have to develop a differential pressure in excess of 28" H20 to provide a vacuum to the CC. I can supply more details of my analysis involving tailpipe pressure vs exhaust flow velocity vs Venturi pressure if needed, but no one would want to clog up their exhaust flow with a Venturi anyway, so I don't think there'd be much reason for giving it.
Cowboy Steve
Posting Guru
Joined: Oct 2007
Posts: 2,225
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From: Farmington, Minnesota
quote:
Don't run the CCV hose up and over the brake cylinder, make sure you can pour a cup of water in the doghouse end and have it drain completely into a cup at the other end. Any other configuration is asking for a potential problem. Don't use a collection trap or hook your CCV hose to your tailpipe!
Why shouldn't you run the hose over the brake cylinder?
Edit: That quote didn't work for some reason
Don't run the CCV hose up and over the brake cylinder, make sure you can pour a cup of water in the doghouse end and have it drain completely into a cup at the other end. Any other configuration is asking for a potential problem. Don't use a collection trap or hook your CCV hose to your tailpipe!
Why shouldn't you run the hose over the brake cylinder?
Edit: That quote didn't work for some reason
Last edited by jhand124; Nov 2, 2007 at 07:17 PM.
Postmaster
Joined: Jun 2006
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From: Fulltime RVer
Originally Posted by powerstroked162
Oh boy Jim, now you've done it! Gene will argue til the day he dies that the venturi effect is not possible. Best of luck to ya Jim, your gonna need it.....
Cowboy Steve
Cowboy Steve
For example, one person claimed that just because he saw the tell tale white mist of the CCV fumes coming from his tailpipe when he hooked his CCV hose to the tailpipe fitting, that he proved there must be a vacuum at the tailpipe fitting which was "sucking" the fumes from his CC.
I tried to explain that the blow by gases in the CC originate from a several thousand psi combustion that leaks past the rings, and the CC pressure will continue to increase until it blows these waste gases out of the CC, and that might mean building a CC pressure of about 1 psi=28" H2O to overcome the back pressure from the tailpipe fitting, or building to an even higher pressure to blow the condensation from an improperly run CCV hose that gets clogged.
Continued high CC pressure might cause oil to leak from the end seals in the turbo bearing because the oil drain back to the CC is a gravity feed that gets slowed by excessive CC pressure. The surface area of the oil pan is more than 100 in2, and that means a 1 psi CC pressure is placing more than a 100 lb load on the pan, and replacing that seal requires pulling the engine!
I just hope my posts here make people think twice before sticking their CCV hose up their tailpipe!
Postmaster
Joined: Jun 2006
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From: Fulltime RVer
Originally Posted by jhand124
Why shouldn't you run the hose over the brake cylinder?
The right angle fitting that I see in most installations increases the resistance to flow by several inches H20 at the higher flows during WOT operation. The up and over means that the reduced flow coming out of the right angle fitting now has to fight against gravity to go up and around another restrictive bend at the brake cylinder. Finally, condensation flows back into the doghouse and saturates the wire mesh which might cause some additional restriction to flow.
My approach is to let everything the CC is trying to vent get out of there with the least resistance possible. Towing a grade I've seen as high as 3" H20 with my minimum back pressure installation. As my rings wear more this number will increase. Racor claims a x4 increase in blow by gases from a new engine to an old high mileage engine ending the end of its service life. Now this doesn't mean a X4 increase in CC pressure, only that the mass flow of blow by gases increases by x4, and this will increase CC pressure by an amount that depends on the restriction of your CCV vent hose.
For about $30 and a half hour installation, everyone can have a CC gauge like is shown in my gallery. I think I can find links to my detailed installation and testing posts if there's an interest. If you tow a lot and start burning a piston, that gauge might save you from blowing an engine.
still plays with trucks
Joined: Mar 2004
Posts: 1,743
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From: Twin Falls Idaho
I routed my CCV mod into my exhaust and and it poses no problems. I did install a one way check valve from an Air Diverter (think old air injection systems of the 80's) It works, you can create a vaccum. I won't argue the point. too much space has been wasted with theorys and disertations. but I put the system in practice and it works for me. I haven't put a guage on it. but I ran the same system on the circle track car years ago and it would pull 15 in. of vaccum at 5000 RPM.
Postmaster
Joined: Jun 2006
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From: Fulltime RVer
Originally Posted by bfife
I routed my CCV mod into my exhaust and and it poses no problems. I did install a one way check valve from an Air Diverter (think old air injection systems of the 80's) It works, you can create a vaccum. I won't argue the point. too much space has been wasted with theorys and disertations. but I put the system in practice and it works for me. I haven't put a guage on it. but I ran the same system on the circle track car years ago and it would pull 15 in. of vaccum at 5000 RPM.
Why not invest $30 in a gauge and make some measurements under different loads. Can you explain why I measured over 20" H20 of positive pressure on Strokin's truck who has a similar setup with his CCV hose going into his tailpipe?
Postmaster
Joined: Jun 2006
Posts: 2,647
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From: Fulltime RVer
Originally Posted by Tenn01PSD350
This is not speculation. This is how International routes theirs. Any questions?
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Hotshot
Joined: Dec 2003
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From: iowa
Well I have not put my ccv hose in my exhaust on my truck but I do run crank case exhaust evac on my race engine, this is a gas engine of coarse, with almost 14:1 compression intentionally setup loose to be fast thus has more blow by then most engines, runs at over 7500 rpms and the evac system produces between 2-5" of vac at WOT and zero at idle thus no preasure. So if these systems don't work please explain this to me because that engine has much more blow by than our psd's do until they have a lot of miles on them.
Post Fiend
Joined: Feb 2006
Posts: 11,892
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From: Middle Tennessee
It goes straight down the back of the block and dumps right there. I have seen this on several commercial trucks.
Monster, I won't pretend to do any analysis on that except that it seems odd the designer/manufacturer of our engines dumps the ccv straight down via a metal tube, and we try to burn it. I would say emissions only.
So if these systems don't work please explain this to me because that engine has much more blow by than our psd's do until they have a lot of miles on them.
Last edited by Tenn01PSD350; Nov 2, 2007 at 09:09 PM.
Hotshot
Joined: Dec 2003
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From: iowa
Tenn I agree running it through the turbo is bad, and my CCV currently goes down from the VC to the frame and back to the rear axle. But this stuff of saying that exhaust evac systems will build pressure is what i am questioning, it's a system that has been run in race engines for 50 yrs effectively and still used to this day by guys that will polish the counter weights on a crankshaft to reduce windage and improve power. I. E. guys that are **** retentive on their engines.
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From: Fulltime RVer
Originally Posted by monsterbaby
Well I have not put my ccv hose in my exhaust on my truck but I do run crank case exhaust evac on my race engine, this is a gas engine of coarse, with almost 14:1 compression intentionally setup loose to be fast thus has more blow by then most engines, runs at over 7500 rpms and the evac system produces between 2-5" of vac at WOT and zero at idle thus no preasure. So if these systems don't work please explain this to me because that engine has much more blow by than our psd's do until they have a lot of miles on them.
Does your gasser engine have a turbo? Seems to me that makes a big difference, because the PSD turbo literally brings the exhaust flow to a screeching halt at the turbine housing, and then the exhaust gases kind of trickle out the tailpipe under a residual pressure of about 2 psi with a stock tailpipe and a pressure of about 1 psi with a larger tailpipe, this is based on data measured by Banks, and I posted it here... https://www.ford-trucks.com/forums/666835-a-quick-way-to-estimate-your-dyno-results.html#post5265024 if you're interested.
The exhaust gas flow in the tailpipe following a turbo is much different than in a high RPM gasser. Much of the flow gets stymied at the turbine, and about 25% of the heat energy is removed. After the turbo the flow is mostly driven by residual expansion pressure as the gas continues to cool. In a gasser the tailpipe flow is driven by the full heat of expansion pressure, the full effect of the pistons pushing it, and throw some sonic pressure waves for good measure. I don't think you can claim that just because it works for a gasser that it will work for a PSD!
I used to race sports cars. I had a 14:1 compression ratio, and removed one of the compression rings on each piston to reduce friction. I had so much blow by that my puke bottle would burp enough oil that I once got blacked flagged. I redesigned my exhaust using a flared trumpet like exhaust piece from a motorcycle and vented to that expansion section which seemly did no harm and was probably not any higher restriction than my vent bottle was. But I used to tear my race engine apart every few races, so I really was worried about long term effects of CC pressure anyway!