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The mkiv Supra Owners Club

Any benefit to keeping the turbo hot?


JamieP

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Is it worth fitting a turbo blanket if everything is fine without it?

 

I have had one on past turbos that have failed and wondered could this have helped towards it?

 

Just got one in the post today and thinking now its not worth fitting as ive been running around in it a couple of months now without one and alls been fine with nothing melting.

 

Thoughts?

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without a blanket your under bonnet temps will be silly high mate especial the way you dive it . Which is no good for your performance as the engine is breathing in such hot air ! and all may be fine now but it wont belong before something give's up under there with the heat . If you don't want the fit the blanket i would rape you manifold and down pipe to keep some of the heat down , I would also advise getting some louvers pressed into the bonnet help the heat escape .

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without a blanket your under bonnet temps will be silly high mate especial the way you dive it . Which is no good for your performance as the engine is breathing in such hot air ! and all may be fine now but it wont belong before something give's up under there with the heat . If you don't want the fit the blanket i would rape you manifold and down pipe to keep some of the heat down , I would also advise getting some louvers pressed into the bonnet help the heat escape .

 

From what I've heard wrapping your manifold = bad?

 

I'm going to heatcoat the exhaust side of the turbo, manifold and downpipe (and maybe midpipe). Is a blanket still neccessary after all that?

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From what I've heard wrapping your manifold = bad?

 

It's OK providing the manifold isn't subjected to forces that will crack it. Some (i.e. Boostlogic) come heatcoated anyway.

 

I'm going to heatcoat the exhaust side of the turbo, manifold and downpipe (and maybe midpipe). Is a blanket still neccessary after all that?

 

I don't think so if you get the ceramic type stuff that a few members have used on here.

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isn't wrapping the manifold supposed to keep the heat in the exhaust so that more of it can be used to spin the impellers, same idea as keeping manifold primary length short so as to reduce the heat loss before the turbo.

 

Exactly that. The turbo is driven by heat so ideally you want the manifold and exhaust housing insulated to keep as much energy in as possible. Doubt it would make too much difference in practice though.

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Ideally, wouldn't it be best to have maximum heat-retention within the manifold/turbo/etc when driving the car (to both keep general under bonnet temps down and also the energy thing) and then miminum heat retention once you aren't pushing the car, i.e. when cooling off and when parked up?

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The theory is that lagging pipework and using a turbo blanket helps keep the inside temps high, so increasing gas speed, however to me keeping heat high within the turbo seems a contradiction in terms, as you don't want high temps, and apparently lagging tube manifolds, can lead to premature cracking:( so neither my manifold nor my turbo is lagged, just a heat shield, and i don't suffer high EGTs and my under bonnet temps are not that bad, my induction temps are on or near ambient, due to having a bumper that permits direct airflow to the filter.

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[snip]

The main reason I wanted mine done was because I wasn't happy with how hot my bonnet was after a spirited run!

 

Surely that's indicative of not cooling the car down afterwards, rather than heat generated while pushing it. That's why track day instructors always tell you to do cool down laps at the end of a session.

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Surely that's indicative of not cooling the car down afterwards, rather than heat generated while pushing it. That's why track day instructors always tell you to do cool down laps at the end of a session.

 

The car was still running at idle. I was more concerned the paintwork would get damaged long term, and that if that's how hot the bonnet was outside, the under bonnet temps were obviously very high.

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I recently had a discussion with someone running a 1000bhp Cosworth engine, they have researched and done a few experiments - conclusioin was jackets / blankets cause hot spots, better to have air moving round the turbo. They have taken the blanket away and added extra insulation to vulnerable parts of the bay. I will be getting rid of mine.

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Well, I've seen a few turbo race car engines at Le Mans, and they have all used heat wrapping. If they do it it'll be for maximum power, response and importantly reliability - it's a pretty harsh environment! If it's good enough for those guys... Here's the Rollcentre racing car from 2005 with a Nissan turbo engine, notice the heat wrapped turbos and downpipes.

DSC_3719.jpg

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The car was still running at idle. I was more concerned the paintwork would get damaged long term, and that if that's how hot the bonnet was outside, the under bonnet temps were obviously very high.

 

Yes, but there's no moving air when you're sat at idle...

 

Well, I've seen a few turbo race car engines at Le Mans, and they have all used heat wrapping. If they do it it'll be for maximum power, response and importantly reliability - it's a pretty harsh environment!

 

...But it only has to last one race, not months/years of daily use.

 

It occurred to me yesterday that exhaust gas temperature only matters to gases still in the system. Any heat that has already escaped into the metalwork is already lost to the gas-flow, so you might as well shed it to atmosphere as soon as possible.

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Yes, I get that. My point is that the heat has already escaped from the gas if the turbo/manifold/downpipe is hot, so heat wrapping traps the heat in the metal, not in the gas.

 

I'm inclined to agree with that, however I'm no physicist:blink:

must admit that even having nothing other than a turbo heat shield, than my under bonnet temps don't seem to get any higher than with twins, and EGTs are low, i wonder if anyone with EGT sensor in the turbo housing has done a comparison test, with and without a jacket?

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