suck thru the head?
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Cruiser
Joined: May 2007
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suck thru the head?
Can the wrap off my V&H quiet baffles get sucked back thru the head and into the cylinder? I heard that when the poppping sound on decel happens its air going back thru. If this is so could it take some insulation with it? I am thinking of using ceramic blanket (2300 degres) and that probably wouldnt help things if this were true. Any experts out there?
Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
RE: suck thru the head?
If it were true, you would be sucking rain, bugs, dust and all other sort of nasties back into the cylinder.
Urban myth....the exhaust is pushed out by the piston raising on the exhaust stoke while the exhaust valve is open, the intake stroke, the intake valve is open and the exhaust is closed.
The popping on decel is unburned fuel getting into the muflers and then igniting caused by air leaks in the exhaust system or to rich of a mixture when the throttle is closed.
Urban myth....the exhaust is pushed out by the piston raising on the exhaust stoke while the exhaust valve is open, the intake stroke, the intake valve is open and the exhaust is closed.
The popping on decel is unburned fuel getting into the muflers and then igniting caused by air leaks in the exhaust system or to rich of a mixture when the throttle is closed.
Advanced
Joined: May 2007
Posts: 65
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From: Bay Area, Left Coast
RE: suck thru the head?
What he said...
Not an expert, but it would seem to me that the chances of your blown out insulation being sucked back through the head are about as much as a golf ball being sucked through a garden hose...
Not an expert, but it would seem to me that the chances of your blown out insulation being sucked back through the head are about as much as a golf ball being sucked through a garden hose...
Outstanding HDF Member
Joined: May 2007
Posts: 2,304
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From: Florida
RE: suck thru the head?
Reversion most certinly will take what ever is in the path and suck it into the head if the pipes are that bad. WE all get reversion in a certin area of our power band...how else would you explain the carbon build up on the back side of the intake valve and into the intake trac.
I've seen that ceramic pipe coating get sucked into the cylinder doing extinsive damage to the cylinder...how ever exhaust fiber glass, I doubt it ever makes it up the pipe far enough for reversion to take it into the cylinder.
As far as the exhaust valve being closed during the intake event....only with a stock cam. Overlap in a hi-performance cam has both valves open at the same time at TDC, the more over lap the longer they are open together.
I've seen that ceramic pipe coating get sucked into the cylinder doing extinsive damage to the cylinder...how ever exhaust fiber glass, I doubt it ever makes it up the pipe far enough for reversion to take it into the cylinder.
As far as the exhaust valve being closed during the intake event....only with a stock cam. Overlap in a hi-performance cam has both valves open at the same time at TDC, the more over lap the longer they are open together.
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Joined: May 2007
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From: Bay Area, Left Coast
RE: suck thru the head?
I agree Doc. I just didn't think the possiblitity of the exhaust fiberglass making it that far was a real concern. As I said though, I am not an expert. Doc is. Be careful what information that you take off and run with...
Outstanding HDF Member
Joined: May 2007
Posts: 2,304
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From: Florida
RE: suck thru the head?
Like I said, I don't see fiberglass from the muffler going up far enough to get caught in the reversion wave to carry it into the head. the Galss will be spit out of the pipe. Your both correct.....just wanted to let you know there is reversion waves going on.
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Cruiser
Joined: May 2007
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RE: suck thru the head?
many thanks to the experts for stepping up. I decided to go with a ceramic blanket wrap instead of the fiberglass. I feel if it comes a bit undone, it would blow out.It sounds awesome runs great. As a side note it didnt pop at all and I hope I didnt screw up.
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Road Warrior
Joined: Jan 2007
Posts: 1,276
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From: Minneapolis Area, MN
RE: suck thru the head?
ORIGINAL: Doc 1
...I've seen that ceramic pipe coating get sucked into the cylinder doing extinsive damage to the cylinder...
...I've seen that ceramic pipe coating get sucked into the cylinder doing extinsive damage to the cylinder...
I just had this done and I hadn't heard anything bad about ceramic coating headers.
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Outstanding HDF Member
Joined: May 2007
Posts: 2,304
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From: Florida
RE: suck thru the head?
Years ago people used to paint the inside of their pipes thinking it would stop the bluing of the chrome( due to a wrong AFR ) After these people realized that the heat coming out of the head was around 1300 degrees and the paint was for 650 degrees this wasn't working.......So some one got the bright idea to coat the inside of the pipe with a ceramic product. Good idea for the temp in the pipe but most people installed this product over a carbon layer and/or anoil soakedpipe. First time down the road the reversion pulse wave took the pieces of ceramic that came off from a poor bond back in to the cylinder doing a lot of damage the the cylinder and exhaust valve seat.
Now this has nothing to do with coating the outside of the pipe so be at ease if this is what you did...lol.
Now this has nothing to do with coating the outside of the pipe so be at ease if this is what you did...lol.
Road Warrior
Joined: Jan 2007
Posts: 1,276
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From: Minneapolis Area, MN
RE: suck thru the head?
ORIGINAL: Doc 1
Now this has nothing to do with coating the outside of the pipe so be at ease if this is what you did...lol.
Now this has nothing to do with coating the outside of the pipe so be at ease if this is what you did...lol.
Maybe I verify with the shop what was actually done to my pipe.