Thread: exhaust scavenging

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i just finished my exhaust up and some people were telling me that wrapping your exhaust increases scavenging...if that is true is it worth the extra weight you add to the car. is it worth the money for the wrap

Thermotec wrap weighs very little. The basic theory is that as the exhaust gas cools, it looses energy, and slows down. I can't say for sure that you will gain power, but it keeps under hood temperatures down, helps prevent heat soak of starter, and will save you from blistered knuckles if you have to work under the hood with hot exhaust.

axhaust scavenging is accomplished with full lenght (long tube) TUNED headers.

What causes the scavenging is that the exhaust gases pulsate (or flow in a bubble) down the header. When this "bubble" reaches the collector, a pulse of negative pressure is sent back up the header tube. Tuned means that it reaches the exhaust valve just as it opens, sucking the new bubble of exhaust gas out of the cylinder.

Wrapping your headers is only a means of keeping the heat from the header tubes from heating up everything under the hood. Basically, ceramic coating does the same thing.

Frank

ok it seems like more than anything its a matter of opinion. ive just got shorty headers and thats all i want to run because i live in rockford il and there are potholes and all kind of bumps around here. long tube headers would be part of my tune up every year if i had them. is there anything i can do to better my exhaust

I tried wrapping a set of headers on my 4x4, didn't drop the temp as much as I hoped it would. I have since swapped to ceramic coated headers and noticed a big difference, that's what I recommend

Sinister is right about ceramic coating. Some years ago, I had a '29 Ford roadster with chrome outside the frame headers. I have scars (header tatoos) on my arms from brushing against a header pipe. Second degree burn every time. After I had them ceramic coated, I happened to brush my arm up against a pipe, and instead of a blister, it only left a red mark. I still got a burn, but there was a big difference in temperature. I usually wore a sleeve when working around hot headers, but sometimes I simply did not want to take the time and my arm paid the price occasionally.

ok thanks for the advice. also i heard of people wrapping there entire exhaust system to increase scavenging what are your opinions on that?

They claim an x-pipe will help in exhaust scavenging.

I cannot say who "They" are, lest I forfeit my life!

Don't bother to wrap the entire exhaust. Road debris will damage the wrap, and it will be hanging in tatters by the year's end. Thermotec gets very delicate after it has been heated. As long as it isn't hit, it will last forever ( insofar as I have had experience with it ) but the stuff does get dam delicate. If the headders are close to the starter, then double wrap them in the area of the starter.

As for burn protection, you can't beat wrap. You can come in after a long run, pop the hood, and touch ( briefly ) the headers and won't even get a red mark.

Another caveat: you can paint the wrap. Just use any color of 1200 degree rated rattle can. My favorite is the aluminum color. Hold the nozzle about 1/2" from the wrap, and soak it. It will smoke like hell the first time you fire up, but the color holds. If you don't paint it, the color will be a light tan, like a paper grocery bag.

ok sweet i wont bother with the exhaust then. our roads are so bad that they have day and night crews around here patching since end of winter...and winter is just about back...sad well thanks alot for the advice i appreciate it, but just out of curiosity does wrapping the entire system do anything

It might keep the underside of your floor boards cooler. But other than that.......... NOTHING!!!!!!!

Frank

I had a 64 falcon with side pipes, and the exhaust came real close to the floor where they wrapped around the front fender. Wrapped them in thermotec and no more hot feet.

haha okay i dont have that problem but thanks for the info fellas

Originally Posted by 91 camaro 383

ok sweet i wont bother with the exhaust then. our roads are so bad that they have day and night crews around here patching since end of winter...and winter is just about back...sad well thanks alot for the advice i appreciate it, but just out of curiosity does wrapping the entire system do anything

Yeah, it'll do two things:
1. Lighten your wallet.
2. Hold the salt water in next to the steel pipe.