Thermotec Project... Rx 400h Exhaust

[Jim Nazium]

Initial product Experience

I have used since 1995 Thermotec exhaust wrap on my project 1993 MR2 Turbo with much success and extremely satisfying results. The main purpose in this application was to offer additional shielding for heat from the Greddy Aftermarket Turbo along with the custom exhaust plumbing (no cats)... the goal was achieved to help reduce under engine heat as well as protect various components from the 22psi pounds of boost being generated by the Turbo and hence much higher exhaust gas temperatures. An additional benefit, was the sound deadening, which was a plus since it helps reduce some of the raspyness of the freeflowing exhaust.

Project I Jeep Grand Cherokee Limited 4.7L - Thermotec'ed

I then experimented with some left over wrap on my 2001 Jeep Grand Cherokee Limited with the 4.7L engine, and I was blown away. The huge benefit was how much quieter the ride became, especially out on the highway. In cabin noise dropped dramatically since the entire length of the exhaust from just after the manifold to the rear of the muffler was wrapped with 2" thermotec exhaust wrap. The results were stunning.

Project II - Lexus RX 400h - Thermotec'ed

Well, project Thermotec Exhaust wrap is now complete on my '06 RX 400h.

One of the things that bothered me was the marbles or diesel like sound the engine makes when you get on the gas. The engine sound is not very fitting for such a class of vehicle. Also, I wanted to enhance the benefit of keeping as much of the exhaust heat in the "exiting" gas flow so as to help keep the catalytic converter at optimum temperatures. As well, this added benefit should keep the engine off longer, hence saving additional fuel.

Well, it has been two weeks since I wrapped 75% of the exhaust. The V6 front half of the 3 cylinders on the front side, feed from the exhaust manifold, into a 1 3/4" pipe. I wrapped that portion of the pipe that comes off of the exhaust manifold, all the way into the Y portion of the other side of the exhaust portion coming off of the other bank of the exhaust manifold and into the first cutoff / or / bolt off section of the exhaust. Doing it this way, helps keep the exhaust in tack and is perfectly bolt on, bolt off in the case you would ever need to remove or replace any portion of the exhaust. I then wrapped the second portion of the exhaust that begins where the original exhaust ends and feeds all the way through a resonator and past the damper (our cars have a nice little exhaust damper directly beneath the front and rear passender area) and onto the where the rear muffler is then bolted on. I wrapped the exhaust resonator as well since it is rather small as well. The final section I wrapped is where the last piece of the exhaust bolts off of and leads toward the front entry of the rear muffler.

The areas that were not wrapped were... catalytic converters (they have there own additional shields), and the rear muffler, as well as the pipe exiting the rear of the muffler that feeds into the chrome tip (there just isn't enough pipe length to wrap). In essence the most accessable part of the exhaust is the most critical in my opinion, and hence gives the maximum results.

Thermotec Exhaust wrap

Above is the link for the homepage of Thermotec.

What is required is two rolls of 100' (black is preferred) 2" exhaust wrap. Approximately 8 stainless steel exhaust "tie wraps", this is what secures the initial part of the wrap to the exhaust and what holds the end of the exhaust wrap to the end of the exhaust your wrapping. They are stainless steel and are designed in accordance for the exhaust wrap, and is part of the Thermotec exhaust wrap kit as well.

It is recommended to soak the exhaust wrap overnight before applying to the exhaust, as it helps in loosening up the "threads" if you will and gives you a much tighter result given the fact the wrap will shrink once dried and then molds itself once it is cured.

During that initial period the wrap will give off a slight smell for about a week or so. Once the wrap is nice and dry, you spray it with a special silicone black spray to help protect and prolong the longevity of the wrap. All of this took about 2hrs to install, and about 30 minutes a week or so later to protect and spray the exhaust wrap.

RESULTS

Damn, what a difference. You need to drive it to believe it.

PLUS ONE: You no longer hear the engine marble / diesel like sound when accelerating. This is huge for me, and the additional sound deadening due to the mechanical noises created from the exiting exhaust from the engine is phenomenal. The engine is much more muted, and the sound eminating is much more V8 like than V6 diesel like.

PLUS TWO: The vehicle, if you can imagine is even quieter when the engine is running at all speeds, especially highway. The passenger cabin while driving is even more stealthy and the exhaust is much more pinpoint in nature. In other words, you no longer feel the exhaust under you and you hear less of it. And from what exhaust noise you do hear, you hear it only from the back of the vehicle, in that that exits from the rear exhaust tip.

PLUS THREE: Pressing on the accelerator is much more forgiving, in that you are not setting off the engine while accelerating from a standstill in city driving. This is not due to my present climate condition, the past two weeks of testing the ambient temperatures have been constant from the previous weeks in the month of march and april (the benefit is not due to warmer climatic conditions, temperatures have been around 32F - 38F on average). Hence the benefit of the exhaust in maintaining overall exhaust temperatures holds true, thanks to the Thermotec Exhaust Wrap. The catalytic converter is holding its optimum temperatures more effeciently hence requiring less engine cycling to keep the catalytic converter efficient.

Early next week I will get back under the vehicle and take some snapshots of the exhaust wrap. I know some of you will think I'm bonkers, or that I went over the edge. Perhaps I had too much free time on my hands, but, say what you will... if only you could drive my Thermotec RX 400h and then compare it with your stock version... then you would be able to fully appreciate the end result. Approximate total cost of this do it yourself mod... $200US maximum.

Cheers,

MadloR

[RX400h]

Excellent writeup! However, I think I would research into this application a bit further, as most header manufacturers will void their warranty if thermal wraps are applied. Apparently, the metal used for exhaust headers is designed to radiate heat outward to help cool the metal itself. Barrier coatings are sometimes used as stated:

Thermal Barrier is an excellent heat barrier and is recommended for the bottom of intake manifolds & exhaust crossovers to reduce heat transfer. It may also be applied to windage trays, crank scrapers and crankshafts for oil shedding. In certain instances Thermal Barrier may be desirable on the inside of oil pans where good heat retention is desired, such as at drag races, where oil in the pan may become cold while waiting in staging lanes.

Although heat and sound are greatly subdued by applying thermal barriers, the potential damage to the underlying metal in exhaust header applications should not be underestimated. I would also check with Lexus to verify whether this type of modification voids its warranty.

Dave

[SKperformance]

I think it sounds great but i would have left the rest of the exhaust after the cat open. It raises the internal temp much higher but serves a purpose in a engine that does not run all the time. On a high powered car it can cause the tubes to melt when abused to such high temps. on a hybrid it seems fine though

[Jim Nazium]

My previous experience with the my Jeep Grand Cherokee Limited 4.7L gave me the confidence to go ahead for my Lexus RX 400h.

Like the Jeep, the Lexus exhaust is stainless (I checked with a magnet). The only metal I found was the bolts that hold the various components that make up the exhaust. Also, please note, that i did not wrap the Headers, nor the catalytic converters. For one, the headers are not accessible, and to really well wrap headers, they really need to be removed from the engine and a 1" wrap is better suited.

On my 2001 Jeep Grand Cherokee Limited 4.7L I did wrap the catalytic converters, they were so far down the exhaust, they in fact were located underneath the front passenger footwells. The heat generated back in '01 through mid '03 by the exhaust and the additional heat generated by the catalytic converters, proved to me that the ThermoTec wrap was more than enough up to the task to handle the daily use over the 3 year period. At that time, the wrap was only available in white and over time turned a dingy light mustard color. Also, back then I didn't use the silicone spray.

This time around I went a step further, by protecting the wrap with the High Temperature Silicone Paint. Also, my experience with the ThermoTec product, and further studies, have showed that even if used on metal exhaust plumbing, the accelerated wear and tear (including rusting out) is so minimal that it doesn't warrant any concern over the long haul and definitely not over the short haul.

Also, I am curious to know as to how wrapping the exhaust can affect a vehicle warranty? If you mean the actual component of the exhaust, then I wouldn't be that concerned because in any case I would probably replace whatever component failed by an aftermarket Japanese quality component. And if and when it fails, I am sure it will be long after the manufactures warranty expires. As for any other components affected by the exhaust wrap, I cannot find what other major or minor component can be affected by such a mod.

Cheers,

MadloR

[retired00]

....

Also, I am curious to know as to how wrapping the exhaust can affect a vehicle warranty? If you mean the actual component of the exhaust, then I wouldn't be that concerned because in any case I would probably replace whatever component failed by an aftermarket Japanese quality component. And if and when it fails, I am sure it will be long after the manufactures warranty expires. As for any other components affected by the exhaust wrap, I cannot find what other major or minor component can be affected by such a mod.

Cheers,

MadloR

Basically, your manufacturer warranty assumes no modifications of any kind, so it's not so much how it affects the vehicle as the fact that it's there. If you ask in advance, the dealer will say it may void your warranty. If you have a problem, he may fix it under warranty, anyway, but modifications with any non-Lexus part give them an out if they need one. He's stuck in the middle on warranty reimbursements if the factory won't accept his claim, and it's tough to seek a "good will" warranty after the normal time or miles if you have a modification. It's kind of like your car insurance that says "no racing" but you took your car to a good driver's school and wrecked it. Now, what?

[RX400h]

I bring up the warranty issue because many header manufacturers state in their warranty that it is voided if the headers are wrapped with a thermal barrier. I had Doug Thorley headers in my 68 Corvette and I remember seeing this warning. I can theorize why this is so. Stainless steel will corrode quite easily if moisture and anaerobic conditions are present. Let's say you take a piece of 316 stainless steel and immerse it in a pool of water. It should remain pristine as long as its passivation "layer" is exposed to moving water. Now take that same piece and bolt a plastic washer to it. After only a few weeks, the stainless steel surface that is under the washer will exhibit pitting corrosion. Perhaps if the entire exhaust pipe is hermetically sealed so that absolutely no moisture may enter, the stainless steel would remain pristine. However, chances are that a wrap of some sort may not completely seal the surface underneath it, allowing crevice (pitting) corrosion to occur.

So the key is to seal the pipes so well that no water could possibly wick its way in and underneath the "barrier".

Dave