Exhaust wrap. Good or bad?

[miket]

Stainless is really a misnomer with 409. Wierd stuff.

I was worried about the salt than just the water alone and sometimes weird things happen at the welds.

I think it will help to not melt the undertray and to keep the underhood temperatures down given the partial grille block.

Thanks for the practical experience and advice.

[miket]

I assumed i'd remove the clamped metal heat shield on the short pipes between the cats and the engine.

[miket]

I looked it up and 409 turns red from heat but doesnt rot out like regular steel except when covered with salt water where it will slowly pit.

The exhaust wrap companies sell a high temperature siicone spray paint to seal the wrap up. For extra protection i'm going to use that to seal the pipe first , then wrap and seal the wrap.

What i wonder is if the wrap fibers stick to the pipe or if they rub the metal with the heat and vibration cycles. If they do the latter then the underneath coat would wear away and maybe a high temp coating of antisieze or lubricant would be a better barrier than paint on the inside.

[Christ]

Originally Posted by miket

I looked it up and 409 turns red from heat but doesnt rot out like regular steel except when covered with salt water where it will slowly pit.

The exhaust wrap companies sell a high temperature siicone spray paint to seal the wrap up. For extra protection i'm going to use that to seal the pipe first , then wrap and seal the wrap.

What i wonder is if the wrap fibers stick to the pipe or if they rub the metal with the heat and vibration cycles. If they do the latter then the underneath coat would wear away and maybe a high temp coating of antisieze or lubricant would be a better barrier than paint on the inside.

No worries about abrading... I've seen headers that have been used in high-temp applications with wrap for years, and still no noticeable abrasion from the wrap.

There's less chance for dirt and moisture to get stuck in the wrap if you wrap it backwards.. from the rear of the pipe to the front.

[miket]

My concern wasnt possible abrading of the metal but a soft paint layer on it. I think i'll unwrap part of the pipe a year after to check how its working.

[ConnClark]

I did a little research last night on how much exhaust wrap can actually help. Your looking at maybe 1 to 1/2 a percent improvement in power. Some of the power gained is because the wrap improves scavenging which allows more fuel to be burned (This doesn't mean that you will burn more fuel).


this link has some useful info and a test done with a graph.
Header Tech - Collector Styles And Coatings - Stock Car Racing Magazine

[miket]

Probably helps a few more percent with turbocharged engines. If i get a 1% bonus in FE than great!

I want to reduce the temperatures under the hood and underneath the truck. Restricting the grille airflow and putting an undertray under the vehicle would make it even more beneficial.

[FlashT]

I've been using exhaust wrap on my TDI for the past couple months and the only noticeable difference is lower under-bonnet temps. I also sprayed my exhaust pipes with Rustoleum high-heat paint to keep the downpipe from rusting. Not sure about the increases in hp though.