Exhaust wrapping

[Leadfoot101]

A friend that I am helping work on a 440 to run dirt track was thinking of using exhaust wrapping to help keep the heat in the pipe so that it would keep the velocity constant and help on performance, that is, horsepower. What are your thoughts about this? Anyone really think that this helps on reducing heat by 50% around the motor like I have read?

[mopar29mod]

I like the wrap but don't think it will be productive on a dirt car, holds the moisture after washing causes more rust. That is a heavy motor in a dirt car what is it in?

[Leadfoot101]

Well, it's been modified. Actually the chassis is from the original car, Monte Carlo. The transmission is a Chevy and the rear is a Ford. The reason for the tranny is Mopar tranny have more problems breaking than Chevy. Bolt pattern was made to accept motor to tranny. I know that you think that that is a big motor for dirt and I'll tell you that weight for that class is 3200lb. and we weigh 3500lb. But the horsepower has made the big difference along with the suspension of leaf springs. I have heard it before that nobody runs big block motors but 2 years ago we ran the Monte Carlo and it just didn't have the horses so we are changing. Now you said that the washing will cause rust but isn't that what the silicone spray is for?

[Rich Kinsley]

I too have heard that the wrap does help with the heat issues but that it causes an early demise to the headers themselves due to rust.

[toad490]

Here's a good link, it turned me off on wrap when I was looking at it for my Cuda.

http://www.centuryperformance.com/ex...e-spg-138.html

[pishta]

Wrap em. Wash it and start the car. The wrap will dry in seconds. As for reduced header life, your are in a race car..how long do you expect that to last? 727 breaking over a TH? Thats a new one. I wrapped mine in my weekend cruiser and will do it again. Runs way cooler under the hood, reduces axhaust header rattles and makes popping the hood less of a liability at cruise ins!

[cudabob496]

For every 10 degrees you lower the carb inlet air temp, you gain 1.5% power.
So, lower it by 50 degrees, thats 7.5% power gain, or a 30 hp gain on a 400 horse engine.

[JVMopar]

My first set of headers I wrapped. They almost lasted 6 months. My second set I didn't wrap and they are 8 years old.

If I would do it again I'd get the ceramic coated headers.

[mopar29mod]

I think the RB is cool but heavy, although when I was stationed in GA there was the one Mopar that used to kick some butt on the chevy guys...I believe it was a 73 Road Runner with the 440. It was a 5/8 mile track and the car really used to out pull everybody on the back stretch and keep up with the front runners in the corners.

[Leadfoot101]

Well, I "hear" everyone's thoughts, and thanks. Though rusting is a problem, so is welding spots that crack and the headers we got last year will maybe last for a few months till we get the new headers that will be wrapped. My driver and I decided to try wrapping this year and see what happens. Wish us luck.

[toad490]

The rusting is NOT caused by water. It's caused by the higher temperature of the header when they have no cooling from wrapping them.


"High temperature oxidation of a metal is a corrosion process involving the reaction between the metal and the atmospheric Oxygen at elevated temperatures.

Oxide scale may be composed of several layers of different oxides. At the temperatures above 1050ºF (566ºC) iron scale consists of three layers: FeO (the layer adjacent to iron), Fe3O4 (middle layer) and Fe2O3 (surface layer)."

Street cars don't have the sustained high EGT of a race car so the effect is not noticable over a short period of time, the reverse is true of a race car.

[cudabob496]

Originally Posted by toad490

The rusting is NOT caused by water. It's caused by the higher temperature of the header when they have no cooling from wrapping them.


"High temperature oxidation of a metal is a corrosion process involving the reaction between the metal and the atmospheric Oxygen at elevated temperatures.

Oxide scale may be composed of several layers of different oxides. At the temperatures above 1050ºF (566ºC) iron scale consists of three layers: FeO (the layer adjacent to iron), Fe3O4 (middle layer) and Fe2O3 (surface layer)."

Street cars don't have the sustained high EGT of a race car so the effect is not noticable over a short period of time, the reverse is true of a race car.

I think you have to have water, even if its water humidity in the air, to allow
electron transfer, to creat rust. So if you wrap, and you live in a humid environment, the header tubes will rust quicker. I don't
think commom iron products will rust if there is not water available (they will form an initial oxide layer, however, but even that may require humidity), at least with the header temps we are talking about. Also, the exhaust gases have a lot of water in them, as well as acids.

[Leadfoot101]

What if I clean the headers up, and spray them with black HR paint before wrapping? Wouldn't this help to "seal" the headers more to last longer? I was also thinking the heating and cooling affect to the headers would also wear on the life of them same as the light bulb coil? With the constant expanding and contracting has to have some effect but if wrapped, would that help to minimize it? I really am looking to increase on horsepower from the wrapping from what I have read so everything has it's drawbacks, right? And while I am on here, any recommending of spark plugs? Thanks guys!

[cudabob496]

Originally Posted by Leadfoot101

What if I clean the headers up, and spray them with black HR paint before wrapping? Wouldn't this help to "seal" the headers more to last longer? I was also thinking the heating and cooling affect to the headers would also wear on the life of them same as the light bulb coil? With the constant expanding and contracting has to have some effect but if wrapped, would that help to minimize it? I really am looking to increase on horsepower from the wrapping from what I have read so everything has it's drawbacks, right? And while I am on here, any recommending of spark plugs? Thanks guys!

NGK Plugs.
As far as wrapping, I don't think you will see anything more than a few hp from the wrapping, as far as exhaust gas temp goes. But you may see 10 to 20 hp if your carb is sucking in cooler air. Plus, cooler headers means wires and stuff last longer.

[toad490]

Originally Posted by Leadfoot101

What if I clean the headers up, and spray them with black HR paint before wrapping? Wouldn't this help to "seal" the headers more to last longer? !

You would think it might help, but I don't know. I can't see what it would hurt to try.

Bob, most race cars have well ventalated engine compartments, hood scoops ect. On a street car a cold air intake system is much more effective than wrapping headers.

[cudabob496]

Originally Posted by toad490

You would think it might help, but I don't know. I can't see what it would hurt to try.

Bob, most race cars have well ventalated engine compartments, hood scoops ect. On a street car a cold air intake system is much more effective than wrapping headers.

I agree. I have a Ramair box. Probably the cheapest horsepower out there!

[Leadfoot101]

It's nice to be able to talk to others that have tried different things and I appreciate you guys for the feedback. Thanks again.

[bulldog426]

Originally Posted by toad490

Bob, most race cars have well ventalated engine compartments, hood scoops ect. On a street car a cold air intake system is much more effective than wrapping headers.

i second that,, but also at the same time on a street car or any car without a ventilated engine compartment, a higher underhood temp, would raise the temperature of the intake manifold, and heat the air going into the engine

[cudabob496]

Originally Posted by bulldog426

i second that,, but also at the same time on a street car or any car without a ventilated engine compartment, a higher underhood temp, would raise the temperature of the intake manifold, and heat the air going into the engine

I suspect most of the intake heat comes from the heads and the hot oil under the intake! A hot carb does not help either. Use a phenolic spacer between the carb and the intake manifold to keep the carb a lot cooler.

Hey, wanna get rich? Design a phenolic spacer between the intake and the
heads

[cudabob496]

Originally Posted by bulldog426

i second that,, but also at the same time on a street car or any car without a ventilated engine compartment, a higher underhood temp, would raise the temperature of the intake manifold, and heat the air going into the engine

Also a well ventilate engine compartment helps the air move easier through the radiator, which helps the engine run cooler. A tight engine compartment is one of the reasons engines overheat, if they have a marginal radiator.

[pishta]

Originally Posted by cudabob496

I suspect most of the intake heat comes from the heads and the hot oil under the intake! A hot carb does not help either. Use a phenolic spacer between the carb and the intake manifold to keep the carb a lot cooler.

Hey, wanna get rich? Design a phenolic spacer between the intake and the
heads

Years ago (15 or so) , I wondered why they didnt make a composite intake, out of Delrin or some other plastic. Turns out they (GM, Caddi, and Ford) do but not for the performance aftermarket. I mean how cheap could you make them out of plastic! Edelbrock mocked up intakes out of fiberglass, wonder if they ever ran these head to heads over the finished product? A Delrin (high temperature plastic) P5249189 spacer kit for Stage VI would be easy on a mill. Hmmm, wonder if there is a market for something like that...$$$

[toad490]

Lead, I just remebered something I read a few years back. How valid it is I don't know but does make some sense. The "tip" was to keep the overlap of the wrapping to less than a 1/4" otherwise you get bands of different temps in the headers which causes different rates of expansion and cooling that caused cracking. It suggested that you make the first wrap and then mark the tape and cut the end at an angle so you didn't have a large area right at the head that was double layered.

Like I said I don't know how much there's to it, so make what you want of it.

[cudabob496]

Originally Posted by pishta

Years ago (15 or so) , I wondered why they didnt make a composite intake, out of Delrin or some other plastic. Turns out they (GM, Caddi, and Ford) do but not for the performance aftermarket. I mean how cheap could you make them out of plastic! Edelbrock mocked up intakes out of fiberglass, wonder if they ever ran these head to heads over the finished product? A Delrin (high temperature plastic) P5249189 spacer kit for Stage VI would be easy on a mill. Hmmm, wonder if there is a market for something like that...$$$

If a motorhead thinks it will give him more horsepower, he'll buy it!

I did have my M1 intake ceramic coated on the outside. Not sure how much that will help, if at all?