The Lotus Cars Community banner

1 - 15 of 15 Posts

·
Registered
Joined
·
913 Posts
Discussion Starter #1
I got a catalog in the mail today, and I honestly did not remember the underhood temps being any lower when I removed my converter in the past. But I saw this in a catalog today and thought it seemed interesting. I just wanted to see if anyone has ever heard of this.
 

Attachments

·
Registered
Joined
·
1,976 Posts
been around a while. Theory is that keeping as much heat inside improves efficiency and thus HP
 

·
Registered
Joined
·
945 Posts
Pretty popular on a lot of boosted cars. Turbos get really hot and keeping heat out of the rest of the engine bay can't hurt. Blankets are lighter than the steel factory heat shields that come on a lot of newer cars, too. Plus keeping heat in the manifold could also help keep the hot air moving through (increased scavenge), which should lead to slightly better spool times.

I don't think I'd ever put one on a car expecting tremendous real power gains, but they are a neat idea especially if you like how they look.
 

·
Banned
Joined
·
938 Posts
Yea.
Purchased a wrapping kit off of European Car Magazine around 1994 for my UR Quattro 84.
Dont know if the mag. Is still around. Good magazine.
Didn't feel any gains. When I'd open the hood it looked as if the engine had some abortion fix and I'd have to explain it for what it was.
 

·
Registered
Joined
·
136 Posts
theres no point. it's all good in theory but it causes the cast metal to get hotter and moisture to sit in there. Usually ending in premature cracking of housings. Dont waste your time unless you are using it prevent melting things in close proximity.
 

·
Registered
Joined
·
935 Posts
re: Turbo insulation

+1

Also the extra heat retained in the turbo tends to fry turbo bearings (faster).

Covering the header is OK, if it is made from good material. COvering the down-pipe is not very useful.

Anton

theres no point. it's all good in theory but it causes the cast metal to get hotter and moisture to sit in there. Usually ending in premature cracking of housings. Dont waste your time unless you are using it prevent melting things in close proximity.
 

·
Cal H
Joined
·
982 Posts
I have some questions and seek advice. Do we have any metallurgists here? I mean someone familiar with the study of metals and their properties in bulk and at the atomic level. Not someone who just reads a lot or is looking up opinions of others on the internet. Someone who can talk metal.
 

·
Registered
Joined
·
252 Posts
Why is the 6/8 cyl. kit a buck less?

I considered a turbo blanket mostly due to the proximity of the chargecooler to the turbo.

After scouring the interweb for information, I wasn't convinced that it would do no harm to the turbo. Blankets have been around for a long time and apparently Lotus chose not to use one for whatever reason.

<Edit: ...just read Cal's post above...lol.>

On the track it's probably worth the risk of shortened turbo life to gain a couple HP or lose a few milliseconds of spool-up time but in my garage I'd rather spend the money on something other than a premature turbo replacement.

YMMV but I decided that it was better to apply insulation directly to things that need to stay cool rather than keep heat inside things that are already really hot.

I've seen a few posts about improving air flow through the engine compartment which seems like a good place to start.
 

·
Registered
Joined
·
1,976 Posts
Why is the 6/8 cyl. kit a buck less?

I considered a turbo blanket mostly due to the proximity of the chargecooler to the turbo.

After scouring the interweb for information, I wasn't convinced that it would do no harm to the turbo. Blankets have been around for a long time and apparently Lotus chose not to use one for whatever reason.
<SNIP>

IMHO better to put insulating/heat reflective material on the chargecooler...
 

·
Registered
Joined
·
327 Posts
That's essentially header wrap. The Buell motorcycles come with a rather very well made stainless header. The guys that have used header wrap on them have experienced corrosion issues under the wrap. As someone mentioned, it tends to trap moisture against the metal.

In aviation, turbine engine heat blankets are a composite laminated panel. Usually with an aluminium backing, insulation material, asbestos, or fiberglass type batting, and then composites, typically fiberglass and resin. Most of the exhaust ducts for turboprop engines tend to be a similar batting material and then a thin stainless material spot welded into place. Essentially, they are very similar to the heat shield on the bottom of the chargecooler. For practical applications, a turbine engine is simply a large turbo charger. I think something in that configuration would be superior.

Something like this
Rigid heat shield, High Performance Thermal Insulation, DBM Technologie
 

·
Registered
Joined
·
3,493 Posts
Using Thermodynamic theory you want the gases to stay as hot as you can for as long as you can. Does it make a difference, probably not enough to measure. What wrapping DOES do is limit the amount of radiated heat to nearby structures and helps to lower the temps in the engine bay. That is a good thing. The bad thing is the parts you wrap get hotter and stay hotter. They are made to handle the heat but it probably does shorten the lives of those parts. On the other hand it helps to prevent them from cooling quickly and that is a good thing. It also reduces noise. It does make servicing harder and does not "add lightness". IMHO it is probably better to wrap than not. I would at the very least wrap the pipe going to the turbo so there is the most amount of heat (read energy) as possible getting to the turbo.
David Teitelbaum
 

·
Registered
Joined
·
935 Posts
re: Turbo heat shield

Agree with below 100%. Form a thermodynamic point of view, we should wrap the whole exhaust.

The problems have nothing to do with above but with some very heat sensitive parts on the turbo. It is the turbo bearing or the center section. Both the compressor and turbine sides can take a lot of heat. It is the bearing and the oil in it that gets cooked (literally). Once it does, the bearing needs replacement. It is $1000. The problem with heat soak in the bearings was the major barrier to tubo adoption in passenger cars. Shut off the engine and the bearing heat soaks and dies. The OEM is in for a $1000 warranty repair part... The solution is to water cool the bearing. That is why all OEM and most aftermarket turbos have a water feed.

If you wrap the turbo. The heat will stay in the turbo. It is made of (mostly) iron. It conducts heat well and will heat soak the bearing. The water cooling so cleverly provided may not be enough! That is why there is no OEM wrapped turbo. They use metal shields but not to keep the heat in but to keep heat away from other parts i.e. channeling its escape.

I wrapped my turbo's once. Blew the bearings during the first 1 hour race and never tried again. :)

Wrapping headers and exhaust pipes is a totally different story. It is a good idea. Given that an OEM or cheap part is made from cast iron or 309 or 409 stainless (originally made for kitchen-ware i.e. knife and forks but works on exhaust parts in a pinch :) ), it will start to scale and oxidize with all that extra heat, so much faster. This is a given. Read the material spec sheet. Iron will start looking ugly, stainless will look like regular iron. Flakes of iron oxide will come out of your exhaust pipe, if the car is not run for a week. Therefore, it will look ugly under the wrap. It will wear out and need replacement faster (depends on how thick the pipe wall was in the first place.) I do not think, this is all that bad. Just beware! caveat emptor!

Take a look at Inconel header that was wrapped. It changed color (chromium oxide is green). It would probably polish up. There is no scale! Take a look at the collector. It is 321 stainless (from Burns). It is starting to look grey and scaly. 321 was designed for WWII aircraft exhaust. 309 and 409 is much worse. Here is a comparison all in one pic. The whole exhaust was wrapped and driven hard i.e warmed up to cherry red.

http://www.lotustalk.com/forums/f163/elise-exige-racing-wide-body-81258/index5.html

Anton

Using Thermodynamic theory you want the gases to stay as hot as you can for as long as you can. Does it make a difference, probably not enough to measure. What wrapping DOES do is limit the amount of radiated heat to nearby structures and helps to lower the temps in the engine bay. That is a good thing. The bad thing is the parts you wrap get hotter and stay hotter. They are made to handle the heat but it probably does shorten the lives of those parts. On the other hand it helps to prevent them from cooling quickly and that is a good thing. It also reduces noise. It does make servicing harder and does not "add lightness". IMHO it is probably better to wrap than not. I would at the very least wrap the pipe going to the turbo so there is the most amount of heat (read energy) as possible getting to the turbo.
David Teitelbaum
 

·
Registered
Joined
·
935 Posts
The wrap to use

Below is a professional formable hard wrap.

The wrap that looks like a bandage in the top pic is for kids. It is hard to install. The metal straps are like razor blades. It frays, disintegrates when wet and hot, etc...

Also oven blankets with foil on outside are great. Easy to install, last forever. The good stuff will take 2200F, but costs a bit more. I have been using it for decades, now. It is calcium or lava-based high-temperature fabric.

Anton


That's essentially header wrap. The Buell motorcycles come with a rather very well made stainless header. The guys that have used header wrap on them have experienced corrosion issues under the wrap. As someone mentioned, it tends to trap moisture against the metal.

In aviation, turbine engine heat blankets are a composite laminated panel. Usually with an aluminium backing, insulation material, asbestos, or fiberglass type batting, and then composites, typically fiberglass and resin. Most of the exhaust ducts for turboprop engines tend to be a similar batting material and then a thin stainless material spot welded into place. Essentially, they are very similar to the heat shield on the bottom of the chargecooler. For practical applications, a turbine engine is simply a large turbo charger. I think something in that configuration would be superior.

Something like this
Rigid heat shield, High Performance Thermal Insulation, DBM Technologie
 

·
Registered
Joined
·
3,493 Posts
Cooking turbo bearings was a bigger problem before the widespread use of synthetic oil. Water cooling the bearings also helps. Running the motor lightly before shutting it down helps with heat soak so the bearings don't "coke up". You should get 50,000 miles out of a turbo on a gas engine if you use good oil and change it regularly and let the motor cool down a little before shutting it off. If you are racing all bets are off. Part of what determines the choice of materiel is the coefficient-of-expansion. Because of the big change in temperature you must select materials that can take the heat cycling and fit together to other materials with different rates of expansion and not crack. And then there is the economics of it all (how much the materials cost and the expense of forming/machining them). What you end up with is the compromise we drive. Will wrapping improve anything? Not enough to justify the cost, otherwise the manufacturer would have done it.
David Teitelbaum
 
1 - 15 of 15 Posts
Top