rboorgu

Anybody got suggestions for a thermal wrap for a stainless steel downpipe. I am trying to reduce my underhood temps

Raj

tmiked

this was just recently discussed.


http://store.summitracing.com/defaul...rt=header+wrap

wylie

All kinds of good stuff

http://www.designengineering.com/products.html

pomanferrari

iTrader: (1)

If you're running a cat. Don't do it. It will ruin your motor.

Not sure if it's ok with a MidPipe.


My turbos looked like this running a cat w/o the thermal wraps. Imagine with the thermal wraps.

https://www.rx7club.com/forum/showth...+nonsequential

volley1

Why will it ruin your motor if you are running a cat? I have a Mild steel dp with thermal wrap on it. Should I take it off?

tmiked

Your turbos dont know if your DP is wrapped or not. I wouldnt worry about it. Watch out for rust on mild steel.

volley1

Yeah, that is why I painted it with high temp ceramic paint. Looked pretty cool before I wrapped it.

RonKMiller

I think it puts less stress on your motor since you are scavenging exhaust gas faster.

Not to mention it will dramatically decrease underhood and tranny tunnel temps as well as prolong the life of rubber and plastic underhood components.

Make sure you do not wrap the head of the dp and never wrap a cat. Put the stock heat shield back in place.

volley1

Which stock heat shield are you talking about?

D-town R2

I wrapped mine with a ceramic blanket backed with aluminum tape. Its about 1/2" thick x 3"x 12'. Just enough for a downpipe. It is designed for temperatures up to 2300 deg F. Mc master carr had it to me in two days, page 3235. Use safety wire or steel bands to hold it in place. $12. Somewhat fragile though.

pomanferrari

iTrader: (1)

Back in the 70s, BMW had a thing called a thermal reactor located very near where the DP and MP would meet on our car. The thermal reactor was supposed to reduce emission by forming a location that has high heat concentration so that combustion would be more complete, i.e., less harmful emission byproducts so that a catalytic converter wouldn't be needed.

Well, they learned that the reactor was so good at keeping heat in, it warped the cylinder heads of the I-6 in just about all of the engines over time.

So wrapping a DP connected to a catalytic converter in our car would in effect arrive at a thermal reactor concept of BMW. This would cause the engine to warp due to the high heat of the turbos etc.

I have a friend with four engine replacements in 4 years all due to coolant leaks through the housings. He's got a real nice wrap between the turbo and the cat. And it's so good that you can almost touch the DP after a 30 minute drive.

At least that's my theory anyway. Now, note that I didn't say it's harmful if you're running with a MP, just with a cat.

Would any one be so kind as to disprove my theory?

tmiked

Several of us have, we are running wrapped DP's

no problemo

RonKMiller

The one directly over top the head of the stock pre-cat.

It pretty much shields some wiring and the ABS unit.

rynberg

It's a good theory, but I'm not sure how valid it is. The 79-80 RX-7s had a thermal reactor and those engines did not suffer coolant seal problems. Albeit, that was obviously not a turbo-charged situation.

DaedelGT

Why would wrapping the DP cause the engine to heat up more? Would the exhaust gasses right after the turbos be any hotter than normal?

Kento

Yes, that's why the FD's turbos spool so quickly, because the exhaust turbines are located right next to the exhaust ports. The abundant energy from these hot gases is transfered to the turbos, which is both a blessing (quick spooling) and a curse (cracked manifolds). As soon as the spent gases leave the combustion chamber, they lose heat. The original concept behind wrapping an exhaust is that hotter gases keep their velocity longer, thus aiding in exhaust port/combustion chamber scavenging (in a NA engine), thus providing more room for fresh intake charge in the CC, thus resulting in more power.

DaedelGT

Maybe I'm just not seeing it. How are the gasses being any hotter than they normally would be? Less heat transferred to the DP? Sure, but so what? The gasses aren't just hanging around up there. If anything I would think the cat would get a little hotter.

Explain away oh mighty Kento. I just can't picture it.

dgeesaman

iTrader: (7)

Can't prove or disprove, but the only way to cause the heat to build up is to make that spot have backpressure. The BMW design had to have some baffles or restriction or else it wouldn't have done anything. A dp adds about 0 backpressure, so the free-flowing exhaust gas would heat the engine less, even though the pipe itself might be hotter from being wrapped.

Dave

tmiked

There's some confusion. In general, some ppl wrap exhaust manifolds between the engine and turbo for increased HP at the cost of possible shorter turbo life. As Kento said, this is not really necessary on the FD or part of this topic, it just somehow got thrown in by post-******

Wrapping the DP just reduces underhood heat with no real negatives.

Kento

Mighty? Hardly....I'm just another rotary/FD junkie

It's not so much that the gases are "hotter than they normally would be"; it's maintaining as much of the heat energy in the combustion gases as possible from the combustion chamber to the exhaust tip.

In a simplistic nutshell: hotter combustion gases travel faster (especially around corners) than cooler combustion gases, because they have more energy. The instant combustion takes place, however, those gases are transfering (losing) their heat energy to all the metal parts they come in contact with, because metal is an excellent heat conductor. This is why ceramic coatings and other heat insulation products have been sought after by race engine builders; the more heat energy you maintain to propel the piston (and in a turbocharged engine, the exhaust turbine blades as well), the more power generated.

I'm not saying that wrapping the DP will affect the longevity of the engine/turbos; that's open to debate. I'm just explaining how the concept of wrapping exhaust headers came to be.

DaedelGT

But how is it any worse than before? That's what I don't get.

Kento

I don't understand what you mean by "worse".

DaedelGT

Wow, I'm stupid. I thought you were arguing in your first post that it is worse for the car to have thermal wrapping on the DP. I thought your original post was in response to me. Ignore me.

DavidDeco

What type of underhood temps have you wrapped DP guys noticed????