Decat heat wrap

[Lefty1991]

Is it worth heat wrapping my decat pipe? If so what length of wrap would i need?

[MR2 Turbo Boy]

Hi bud..

Long time no speak..

How's it going..?..

Had the car remapped, since last spoke to you, at the ph meet..

Answer to your question, I'm not sure either... A lot of mixed reviews..

[ashley]

Don't bother

[Lefty1991]

How's it going, what did you make in the end? That's the next thing on my list to do, just changed the clutch and fitted a fidanza flywheel. Off to the pod on the 20th to try my hand at the 1/4 mile

[MR2 Turbo Boy]

Not bad bud..

Made 515fwhp... And 445hp at the wheels...

Cheers Ashley..

[MR2 Turbo Boy]

Bud ..

Going to the last Goodwood breakfast meet this Sunday... You fancy coming along.. The theme is Italian cars..

[Lefty1991]

I did see that but I'm working.
Are you putting a 355 body kit on and pretending its Italian?

[Lefty1991]

No one else got an opinion on heat wrapping?

[tubby_tony]

As MR2 Turbo Boy says lots of mixed reviews and if you just put "heat wrap downpipe" into the search section and select search for all terms you get lots of info.

[MR2 Turbo Boy]

I did see that but I'm working.
Are you putting a 355 body kit on and pretending its Italian?

God, NO...

I was thinking of purchasing TRD kit of fimmo...

[bobhatton]

Is it worth heat wrapping my decat pipe? If so what length of wrap would i need?

Why would you want to do that?

[Lefty1991]

To hopefully reduce engine bay residual heat and possibly encourage better flow through the exhaust. Was only an idea as I have to remove the pipe for my mot

[bobhatton]

To hopefully reduce engine bay residual heat and possibly encourage better flow through the exhaust. Was only an idea as I have to remove the pipe for my mot

It may reduce the heat in the engine bay, but not by much.

It will never give better flow through the exhaust, I do not know where that idea comes from. By keeping the heat in the down pipe the air is hot so is expanded, a bigger volume trying to get out. Because of the bigger volume trying to get out the pipe work there will be a resistance to the flow of air, a back pressure on the turbo.

By reducing the back pressure after the turbo one can gain an increase in power, in fact that is the first place to do any work on a turbo car to get more power.

So the down pipe needs to be cooled, not hot

[KarlBristol]

Besides the lack of gains, thus making this a rather pointless exercise - I've heard an awful lot of horror stories about cracking pipes due to them being wrapped. It doesn't seem worth the risk in my opinion

[Lefty1991]

Okay thxs for the opinions

[audicab26]

The following paragraph is from one of the best tuning books on MR2s

"Being bolted directly to the business side of the turbo charger, the down pipe sees an incredible amount of heat, as exhaust gas temps can rise well over 1000 degrees f. wrapping the exhaust is a way of keeping heat in the downpipe to encourage exhaust scavenging, and keeping it out of the engine bay. Exhaust wrapping is a budget alternative to the superior process of expensive high temperature coatings"

I researched this subject and wrapped my exhaust all the way to the silencer boxes I have also wrapped the pipes to and from my alloy side mount inter cooler. Think about it hot air is less dense and flows faster that why exhausts are wrapped, cold air is more dense thats the whole idea behind inter coolers, engine bay temperatures are the Achilles heal of the mr2s mid mounted engine location, this is a very credible mod that works well, I have also manufactured my own heat shield that blanks my k&n cone filter off from the engine bay so that it's only pulling in cold air from the side vent.

I used about 50 metres of wrap but I wrapped it pretty thick, and just to silence the sceptics I used a digital temp gauge before and after in my garage with the engine idling for 5 minutes each time at operating temp before and after, the temperature reduction was 22 degrees centigrade evidence enough for me
Hope this helps

[Lefty1991]

Audicab26, thank you for the feedback, I'm still undecided but will probably go for it, starting with the down pipe and possibly the rest at a later date

[ashley]

If you read books specifically on tuning turbo charged engines (non MR2 specific), the best exhaust on a turbo is often quoted as no exhaust. Anything you can do to eliminate back pressure will increase the pressure differential across the turbine, and allow increased flow....this includes reducing pressure in the exhaust- and volume for volume hot gasses are under more pressure (so wrapping the exhaust and keeping the heat in is going to limit the flow you can achieve).

Exhaust scavenging on a turbo is much much less relevant, you have a turbo in the way...

On the MR2 you can struggle with engine bay temperatures, which can lead to heat soak as well as hotter intake temperatures as hot air is drawn into the air filter. This would be the only reason I can see to wrap down pipes and exhausts on our cars, but there are other ways to avoid heat soak and inducting hot air that do not involve keeping the heat in the exhaust.

As with most things it's all a compromise, to my mind thew best option is to do your best to reduce back pressure in the exhaust if you want to make big power, and then add cooling to the engine bay itself and shield the induction

[audicab26]

I agree with Ashley,s last post but the mr2 is a very different animal to most turbo charged cars and given that most turbo owners are running 3" plus diameter exhausts my feelings and findings are that there are more gains in wrapping the exhaust and keeping bay temps down against any minimal hike in back pressure I run my car at around 275 bhp which in my opinion is more than adequate for the cars ability in street use, and certainly keeps me well entertained. since wrapping and reducing engine temps I have found that the car is more responsive on the throttle and certainly accelerates better when at temperature.

My experience of turbo cars goes way back to 1986 when my first turbo was a Nissan Sylvia s12, these cars ran at only 130bhp and we're not equipped with an inter cooler, the one thing I always remember about that car was that on cold winters mornings and cold days the car was like s**t off a shovel warm days were crap "it's about keeping it as cool as possible and unfortunately we have a car with crap cooling characteristics hence all the vents fans and mods people make to get cold air in, stop taking the pain killers and cure the disease"

This is purely my opinion on wrapping the exhaust and how I feel I have gained from doing it. Everybody has their own take on things but hey this has worked for me and worked well.

[ashley]

Yep- at those power levels with a 3 inch exhaust you're into the realms of diminishing returns where it comes to back pressure...with a stock 2.5 inch downpipe however, it's a different matter...