Exhaust, exhaust, exhaust!!!!

[ericeash]

i must say that the factory exhaust is a work of art!! beautiful. no my question cause you knew i had one; what are the differences in the mild steel and stainless steel exhausts? any weight difference? if not i plan on buying the mild steel version and then coating it with some ceramic or other coating. www.hpcoatings.com looks like the ticket. has anyone coated their headers. i did this on my ducati and got a much needed cooler exhaust cause my calves and arse were hating the heat, and also got a little more power. i just know it would help greatly with the big horsepower motors going into these ultimas. also i've heard of hot air coming back into the interior and i know this could help also. the stainless exhaust looks great, but the coatings this place offer will offer the same look and rustproof you exhaust too. plus more power which i'm all about. cheers.

eric

[mkoch1]

The stainless may be thinner and lighter than the mild steel. I personally would go with the mild + ceramic coat them. Then you get the corrosion protection of stainless, you'll maintaining high exhaust velocity because you are keeping the heat inside the tube with the inner coating, and the external coating will cut down on radiant heat. Or get the stainless and wrap them in exhaust wrap.

mark

[ericeash]

yeah, i don't think with a 2200-pound car putting out over 500hp makes much of a difference what the weight of the exhaust is. maybe a full aluminum exhaust would see a weight difference but even then probably only 20-30lbs. i think you could save a few hundred bucks and come out with a better exhaust by going mild and coating it. that site i mentioned has different color coatings and one would make it look just like stainless. i just wanted to make it a question and spread some info.

eric

[ericeash]

check this out, i sent an email to this place and here's what they said;

Thank you for your interest in HPC. The cost to coat most full length V8 street-type headers inside and out with our HiPerCoat® polished aluminum finish is $220.00, outside only is $165.00. Colors other than polished aluminum, such as semi-gloss black, gray, blue, red, green and purple add $66.00 to the set. Used headers will be chemically, thermally and mechanically stripped before we grit blast them as prep for coating. This insures that we start with virgin metal and eliminate any carbon, combustion deposits and microscopic rust. There is a $20.00 charge for this process, but HPC guarantees against rust and corrosion for as long as you own the coated headers, regardless of whether the parts are new or used.

in the US that would be a $500+ savings over stainless steel and you'd ultimately have a better product.

eric

[Stig]

Be aware that there's quite a long wait for the non-stainless exhausts (there's a fair one for stainless too at the mo).

If you want to go this route, be sure to get the order in pronto.

[jschwartz]

All my ZR1 buddies put on Stainless headers and have them HPC or Jet Hot coated to reduce engine bay heat.
Stainless is better for High Heat than Mild steel. Car Craft recently tested coated vs uncoated headers and measured a drop in surface temperature from 560 deg to 260 deg F

[ericeash]

there's also a fair amount of wait time on me buying the kit so that doesn't matter too much. plus, since i plan on building the entire kit by myself along with the motor, i think i'll have plenty of time to wait after i start til when i need the exhaust. if i live in england, i'd have already bought some stages and started, but since the parts will be shipped to the states, i have to wait til i can take full advantage of their free shipping offer. hope it's still around when i purchase.

eric

[ultimaandy]

Stainless will also be noisier.

I have the factory stainless system and am going to wrap the headers. I personnely would go for Mild steel and have it coated, IMHO, it'll last as long, look just as good, be quieter (mine is currently 108db's) and cost around the same all in.

It is my intention to drop the db's of my car by 10db's before the factory day!

[ericeash]

that's odd that one would be more noisy than the other. i do remember looking somewhere and seeing that the factory offers multiple silencing options, haven't seen it discussed though. i also plan on putting sound deadening material through the cockpit, so the radio will be able to be heard. i love the sound of a good engine, especially a desmoquattro at 9000-10000 revs, but tunes come in handy. although i could, i don't think the wife could listen to only exhaust note. j, i could see why stainless would be the better choice over mild for wear and tear, but i think the coating would overcome that. i've also used wraps on my bike and the coatings just look better i think. the long list of questions and issues prior to purchase has started.

eric

[bluesatin]

Andy

Be very careful of exhaust wrap. Its fine on low (use)mileage race cars but can cause problems on high mileage road cars. I have found that the themal cycle can change the structure of the metal resulting in failure in stress areas. The constant cycle of rapid warm up and slow cool down resulted in cracks in the exhaust. Just my experience on a stainless header and in no way related to factory, stig, vez or anybody else

[jschwartz]

The headers will deteriorate much faster with them wrapped. It holds in the heat and fatigues the metal.

[ultimapaul]

bluesatin said: Andy

Be very careful of exhaust wrap. Its fine on low (use)mileage race cars but can cause problems on high mileage road cars. I have found that the themal cycle can change the structure of the metal resulting in failure in stress areas. The constant cycle of rapid warm up and slow cool down resulted in cracks in the exhaust. Just my experience on a stainless header and in no way related to factory, stig, vez or anybody else

You must have missed out some sort of caviate in there ..... I think I'll sue!

[ultiman]

There was a whole thread on this very subject a few months back. l cant remember the title otherwise l would tell you. The result was along the lines of what Satin says. Things are never easy are they?

[ultimaandy]

Low mileage race cars you say.....perfect

Seriously though, thanks for the heads up, I'm trying to keep the heat in the exhaust to speed the gasses up and hopefully help with the 'noise @ track' issue.
I will do some further thinking.

Eric.
Mild steel has better sound insulation properties (I think its to do with the heat transferance) than stainless which is the why one will be quieter.
I also believe you are correct, the factory do do more than one silencer, I recon I have the noisiest one!

[stig]

Same is true ON low mileage race cars. I've seen several cracked headers on Sevens that have had the exhausts wrapped. None on unwrapped ones.

Paul - Caveat Emptor

[ericeash]

very interesting stuff none the less. hpc offers a fantastic warranty which would have to include the coating causing the headers to crack, but who knows. they also coat the inside which i think might help the problem of deterioration. since i'm sure very few of you drive your ultima's daily, it shouldn't be too much of a factor. i had a high performance trans-am which would suffer greatly in heavy traffic, no doubt some coating would've solved the problem.

eric