Can it really make the exhaust more efficient? I heard that if you keep the gas as hot as possible all the way out, it moves faster and can actually be more efficient. Is this true, and would wrapping from the header back be a feasable idea?

 

umm well depends on what you mean by that...if its hotter when its combusting the answer is yes it would be more efficient because its just a carnot engine and the more difference there is in temperature between the hot sink and the cold sink the more efficient the engine will be now if your talking about hotter through the exhaust piping it really wouldnt make much of a difference and if anything keeping that much hotter to make it move out faster could eventually cause you to lose backpressure and that wouldnt be good

 

I use this on my street bike,(only on the header) works a little but not recomended for regular everyday use. When the wrap gets wet it locks the moisture to header and causes it to rot.
on our little 130hp Protege's....hardly worth the effort. You would be better off to wrap your intake tube (if you have a CAI)and further reduce heat soak into the air charge.

 

not to sound like a pompus *** but what do you think a backfire is? its when you loose backpressure...now is a backfire good? no all the heated air that builds up in your exhaust is what gives your backpressure (because heat causes pressure to rise) so loosing backpressure and keeping heat in your exhaust are two totally contradictory things...without backpressure your car wont move anywhere, go get yourself a large enough exhaust and lose backpressure and we will see how fast you drive around town (thats why when people put these rediculously large exhaust systems on their cars and dont do anything else to help the horsepower out it doesnt cause much of a gain in horsepower, because without enough horsepower the exhaust has too large of an exit hole without enough gas being combusted to hold the heat in the exhaust)...so your right you DO need to keep heat in the exhaust, but you DONT want to lose backpressure...

 

So Jesse, what exactly makes it a bad idea for a daily driver? I live in a fairly dry city, but when it rains, it pours, and I need to drive in it. Wouldn't the heat from the exhaust burn off the moisture?

 

i agree with psuedo. The point of a tuned exhaust is to evacuate the gases AS FAST AS POSSIBLE with AS LITTLE BACKPRESSURE as you can. It's a very touchy balance. Yes people with say a 3" exhaust on a stock 100hp car are hurting themselves b/c the exhaust is becoming turbulent in the pipes instead of flowing out. In the same notion shrinking the pipe size to increase gas speed is ideal, but you have to stop somewhere or you begin to choke the engine with backpressure (say if you had a .25" exhaust). This is why people call backpressure parasitic.

The proof is in the pudding. But backpressure is not all bad. Some backpressure (in most cars) is used to control the exhaust pulses (as psuedo said) which maintains a constant pressure in the pipes.

 

Not necessarily. Moisture still tends to get trapped under the wrap, and when the moisture under the wrap DOES get hot enough, it turns into superheated steam. One of the best ways to get steel to rust quickly is to blast it with steam.

FWIW some types of ceramic coating will also keep heat inside the header like wrap does, but without the corrosion problems. It's just more expensive than header wrap.

 

That's what I'd suggest as well. Jet Hot is my all time favorite.

http://www.jet-hot.com/

I'd never use a wrap on a daily driven street vehicle. Actually, I'd never use it period. Ceramic coating is by far more expensive, but lasts the test of time, and won't hurt a thing.

I plan on sending my AWR header (if the damn thing ever gets here) to Jet Hot.

HTH - Jim

 

I feel there needs to be some corrections on the above statement.

1. A backfire is not a loss of backpressure, it's extra fuel in the exhaust which explodes when it gets hot enough - like from the next exhaust port firing into the fuel vapor in the exhaust. Caused by an incomplete combustion cycle from any number of reasons.
2. Heat in the exhaust isn't the expanding air that gives you backpressure, the air is restricted from even pushing through a pipe and you've got a muffler and such with restrictions that create a few PSI of pressure in the exhaust system.
3. No backpressure is a good thing cause your engine doesn't have to work as much to push the exhaust gas out. But the over loud exhausts don't add enough on small engines really. Find a little dirtbike, purposely restrict the exhaust and you'll loose power (read anything on cars with plugged cat converters), then pull the muffler all the way off, you'll gain power. Manufacturers design the valving in the engine with a particular backpressure in mind, if it changes you may start blowing just a bit of your not-yet-combusted intake air/fuel out the pipe which could backfire if there's enough of it.

So you can add whatever wrap you like to keep the exhaust hot - it should keep corrosives evaporated in the pipes so there's less rust... this is why highway driving is better for the exhaust cause it lets anything in there burn / evaporate away. Short drives can leave condensation in the exhaust = moisture with corrosive exhaust gasses in it = rusted out pipes.

 

Sure it evaporates the moisture away.




When your driving it. What happens when it rains overnight and you don't drive your car for a day or two? Even if you do drive it the morning after it rains, moisture still sat there and settled.

 

yea i've heard that the wrap can absorb moisture and mold / rott and such. I've been curious if the fiberglass tape muffler bandage stuff can be used to rustproof the pipe? has anyone tried this? though it probably won't wrap smoothly and seal everything in any case.

 

If you want it - i have a roll of wrap you can have for $5 plus shipping.

 

hey yall , beings yall are talking about exhaust, can someone tell me what the 07 2.3 hatch sounds like straight piped behind cat conv, or is there a special muffler i can put on it to sound good, i dont have the speed, any info would be greatly appreciated

 

We are the 3rd Genners - so i am not sure we can help you...

 

It'll probably sound much like hell.. as any 4-cyl with no muffler does.