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Wed Jul 16, 2008 6:09 pm

Does anyone here use exhaust wrap? Does it cause exhaust pipes to overheat, crack etc?

Wed Jul 16, 2008 6:12 pm

It causes them to rust before your very eyes.

Wed Jul 16, 2008 6:43 pm

I have, it works great for a short term fix. assuming your talking about the plastic woven exhaust wrap that seals up as it melts from the exhaust heat.
it's been a while but seems to me it was good for a week or so til I got a chance to replace the already rusted or cracked exhaust.

Wed Jul 16, 2008 8:02 pm

Maybe I should clarify... the exhaust wrap is fiberglass rated to 2000F. My exhaust is Stebro stainless steel.

Wed Jul 16, 2008 8:41 pm

Exhaust wrap insulates the pipes so the gases stay hotter and move faster, which can improve performance on a tuned system but the benefits may be negligible on a non-tuned system. Like the stock configuration.

Most manufacturers of exhaust systems will void your warranty immediately if you wrap the exhaust. The problem is it can trap moisture and doesn't let the pipes dry out. You can predict the results of that. But on a stainless system, well, I'll let you be the judge. In any case I would contact the manufacturer and ask their advice.

Wed Jul 16, 2008 9:58 pm

I would think it would help to keep heat away from the heads and motor and thus be a good thing in the setting of a stainless header or J-pipe. Besides, I wouldn't hold my breath for any kind of warranty coverage on Condelli's pipes.

Thu Jul 17, 2008 1:21 am

I scoped it out as part of my planning for the Zetec conversion. On my version, the first one they made, not the new one, the high flow intake is in the engine bay, right above the cat, and I thought the logical thought that less heat in the bay = lower intake temps, plus the higher throughput of hotter gases, would get me maybe 5-10 hp. Since the system is stainless its all good there. So I called Jim Akiba and he said they once wrapped the manifold on Brady's Syncro, and the stuff had shredded within a year. It doesn't last. Plus, with all the data logging they've done while driving, engine bay/intake temps are ambient at anything above 35 mph anyway, so little benefit for the average non-performance vehicle driver in general, and really no difference at all on the highway. Their data is from a Zetec, but the Zetec runs a good bit hotter than the waterboxer does.

However, I like many of the DEI products, and they market a spray to coat their wrap with and said it can be maintained and will last 5 years. I was tempted, and maybe something good would have come, but I didn't think it was worth removing my manifold and exhaust pieces to do the job right. The DEI product was the most engineered system I saw out there though, if you're game. In the stock German rig, you might get just as good results and other benefits by spending the time and money on a good oil cooler instead.

Roll on,
Broseph

Thu Jul 17, 2008 3:47 am

tencentlife wrote: Exhaust wrap insulates the pipes so the gases stay hotter and move faster, which can improve performance on a tuned system but the benefits may be negligible on a non-tuned system. Like the stock configuration.

Most manufacturers of exhaust systems will void your warranty immediately if you wrap the exhaust. The problem is it can trap moisture and doesn't let the pipes dry out. You can predict the results of that. But on a stainless system, well, I'll let you be the judge. In any case I would contact the manufacturer and ask their advice.

I've seen this used by bikers quite a bit (exhaust wrap). I figured it was for one of 3 reasons:

1) What you mentioned as to the hotter exhaust gases moving faster.

2) Too cheap to buy heat shields, and thing the exhaust wrap will
help from burning the inside of their lower leg.

3) It looks cool (opinion for sure)

Thu Jul 17, 2008 6:25 am

Broseph wrote: I scoped it out as part of my planning for the Zetec conversion. On my version, the first one they made, not the new one, the high flow intake is in the engine bay, right above the cat, and I thought the logical thought that less heat in the bay = lower intake temps, plus the higher throughput of hotter gases, would get me maybe 5-10 hp. Since the system is stainless its all good there. So I called Jim Akiba and he said they once wrapped the manifold on Brady's Syncro, and the stuff had shredded within a year. It doesn't last. Plus, with all the data logging they've done while driving, engine bay/intake temps are ambient at anything above 35 mph anyway, so little benefit for the average non-performance vehicle driver in general, and really no difference at all on the highway. Their data is from a Zetec, but the Zetec runs a good bit hotter than the waterboxer does.

However, I like many of the DEI products, and they market a spray to coat their wrap with and said it can be maintained and will last 5 years. I was tempted, and maybe something good would have come, but I didn't think it was worth removing my manifold and exhaust pieces to do the job right. The DEI product was the most engineered system I saw out there though, if you're game. In the stock German rig, you might get just as good results and other benefits by spending the time and money on a good oil cooler instead.

Roll on,
Broseph

Thanks, Broseph. I've dealt with Jim of Bostig before and I think he's knowledgeable. Since there's no difference above 35 mph and I do not drive in town much, I will not wrap my exhaust. I will wrap the coolant line above the j-pipe, just to limit radiant heating.

Thu Jul 17, 2008 7:15 am

I wrapped my coolant pipe there with 2" Reflectix foil tape. It's dirty but has held up well for over a year. It's not prone to shredding like the exhaust wrap would be.

Covering exhaust, or even ceramic coating, does also reduce the amount of heat radiating off the pipes and thereby lowers engine bay temps. I've always seen that as a very minor side benefit. I think those guys may still be hashing out the design intention of the D-pillar venting over on that thread about it, but the discussion long ago descended into ridiculousness and it became uninteresting. Bottom line is there is terrific air exchange within the engine bay at roadspeeds, and unlike any front-engine car you don't have the radiator dumping all the engine's waste heat right back onto it. Keeping things cooler is generally a good thing, but what lengths you have to go to must be weighed against the benefits. The benefits of cooling the engine bay are negligible because it isn't that hot to begin with.

If the aim is to retain exhaust heat to improve performance, it's right off the heads where you need to do it. By the time you get to the J-pipe or collector, the gases have cooled so much that there's no benefit to be had there, unless you already covered the pipes beginning right at the ports.

Thu Jul 17, 2008 9:02 am

No to exhaust wrap, yes to something like Jet Hot Coating. Removing ambient heat from an engine compartment is a good idea in hot climates. To really see a gain in hp and torque, I would think you would need a way to tune the ignition and fuel beyond what is stock.

Thu Jul 17, 2008 4:57 pm

I would defer to 10cent on VW's but I wrapped the exhaust on my MCI Detroit, it too is a rear eng. Wrapping the exhaust before the turbo (if any) increases the efficiency of the turbo by as much as 10%, because it keeps the hot gasses as expanded as possible. I also wrapped part of the exhaust because it was close to other stuff that didnt need heat. I took great care with it, used hose clamps rather than the tinny clamps supplied. You soak it in water to put it on, then after it has dried you spray the wrap liberally with the paint supplied. I did this three years ago, the only downside that I can see is that you cant pressure wash it. If you paint it enough to seal it, I dont think it will rust, and if you are really concerned about rusting, possibly a coat of hi temp paint on the steel before you wrap. I have no opinion on wrapping the Westie, but if you blew a fuel line, maybe ---------- no it probably would burn anyway.

Thu Jul 17, 2008 7:49 pm

Yeah a turbo exhaust is going to put out way more heat, and also the benefit in power of insulating the header to the turbo is too good to miss. That pipe is going to cook off water more than the cooler downline pipes on either a turbo or NA system. The headers near the heads will also cook themselves clean, I would think, on any system, but where the pipes get cooler I could see where there could be corrosion problems, depending on the climate and the type of product and its appplication.

Fri Jul 18, 2008 6:56 am

Our experience with header wrap was on 4 cylinder Water Cooled vw race cars. I can tell you after a season of racing, the mild steel headers were turned into something so brittle it would crack by looking at it. Welding on it became impossible. I think stainless would be better suited for this application. Our exhaust would see 1400 degrees on every shift.

Fri Jul 18, 2008 2:29 pm

Correct me if I'm wrong here, but I've been under the impression that stainless suffers more from heat embrittlement than mild steel. That's one of the reasons some do not prefer it for exhaust systems, as cracking near the exhaust ports happens sooner. If that's true, wrapping a SS exhaust might short-life it pretty severely. I imagine the grade of SS will have a huge effect on this, as the different grades have markedly different qualities.

The more I learn about this (and going into the exhaust manufacturing business as a cottage industry, I have a vested interest in knowing), the more I come to believe that good inside and out ceramic-coating on mild steel pipes may be the best overall combo for performance and longevity at reasonable cost. I have several copies of my header system being treated this way as we speak. But to really know the answer will take many miles of real-world use.

Fri Jul 18, 2008 2:47 pm

tencentlife wrote: Correct me if I'm wrong here, but I've been under the impression that stainless suffers more from heat embrittlement than mild steel. That's one of the reasons some do not prefer it for exhaust systems, as cracking near the exhaust ports happens sooner. If that's true, wrapping a SS exhaust might short-life it pretty severely. I imagine the grade of SS will have a huge effect on this, as the different grades have markedly different qualities.

This would be true. Just ask the Subaru WRX/STi guys about it. they will tell you that wrapping stainless is a recipe for early failure.

However, the actual grade of stainless makes a big difference. 304 is the most common in use for the exhaust industry because of it's relative cost and availability. 321 is the top dog when it comes to stainless exhaust. It's much more resistant to fatigue cracking.

Standard run of the mill ceramic coatings seem to work fairly well for the cost. However, I have heard that even though some coating companies claim that they can coat a header inside and out and make it last, the reality is that it just isn't true. The argument is that it is nearly impossible to properly prep the tubing deep in the bowls. Perfectly degreasing and sandblasting is tough deep down in the tubes. I have also heard from some that even when extra measures are gone through in an effort to properly prep the inside of the tubes, the additional heat inside the tubes breaks down the coating fairly quickly and it ends up coming ofin flakes. The turbo people have had turbos ruined by the extra crap going through the turbines.

As far as I know, the ultimate exhaust coating going right now is done be Swain Tech. http://www.swaintech.com/store.asp?pid=10969