Thermal blankets and coatings for turbos

I stumbled upon a good article which articulates what I was seeing on the 2010 golf tdi with GTB2060VKLR and a turbo blanket. Basically, the car had a stock like turbo spool and reduced under hood temps. It was a nice setup and honestly what I would consider as the creme de la creme for daily driver CRs. Fast forward to today and I'm now currently in the process of building another AHU with a BV43 and will be applying the same concept. The goal is to try and reduce some turbo lag, so the response curve is like the stock turbo. On our cars, we are only talking about ~5nm of torque increase, but there are much more benefits here in reducing emissions, and IAT temps for those of us who are looking for fuel economy and performance. Interesting paper none the less!, I'd love to see a similar comparison for insulating the intake track .

https://docs.google.com/file/d/0B1DKgBxqE0JEME5wQ1pIc1N5dU0/edit?pli=1

Seems like a good idea. I don't think you'd see nearly the same benefit (if any really) by insulating the intake piping.

Withe The old 1962-1966 Corvair TurboCharged engine, hot rodders soon started wrapping the exhaust pipe to the turbocharger with insulating material. This added about 10% to the peak horsepower and spooled the turbo quicker for more low end power.
Now, the TDI turbo is much closer to the exhaust stream than the turbo on the Corvair, but it stands to anything keeping exhaust heat prior to the turbo is good for more power out from the turbocharger.
A turbo blanket also keeps the engine compartment a bit cooler as an added feature.

Well I sent out a pd130 intake manifold, my ASV turbo manifold, and my BV43 turbo housing to get coated. I'll also be wrapping my downpipe a bit as well to see if I can drop engine bay temps. This is because I am running an underhood intercooler. I'll do some logging, but I should be able to net a healthy change in IATs over factory not coated. The intercooler piping I would agree isn't much value in coating as the thermal properties of fiberplastic and rubber aren't nearly the same as an aluminum pipe.

Nice. Wrapping the downpipe will also help increase the velocity of exhaust gasses leaving the turbo.

turbobrick240 said:

Nice. Wrapping the downpipe will also help increase the velocity of exhaust gasses leaving the turbo.

Click to expand...

I'd have to see the data supporting any advantage this provides.
I guess a smaller pipe diameter would have the same effect, right?

As far as coating the intake manifold, you'd be better off insulating it from
the cylinder head since that's where the added heat is coming from.
The IAT will always be higher than ambient so why not let it radiate freely?

flee said:

I'd have to see the data supporting any advantage this provides.
I guess a smaller pipe diameter would have the same effect, right?

As far as coating the intake manifold, you'd be better off insulating it from
the cylinder head since that's where the added heat is coming from.
The IAT will always be higher than ambient so why not let it radiate freely?

Click to expand...

I don't have the data on hand, but highly recommend 'Maximum Boost' by Corky Bell. It's somewhat outdated now, but the basic principles of thermodynamics relating to turbocharging still hold true. Also, the intake manifold on the ahu sits in very close proximity to the exhaust manifold and turbo, so it gets exposed to a lot more than ambient temps.

turbobrick240 said:

I don't have the data on hand, but highly recommend 'Maximum Boost' by Corky Bell. It's somewhat outdated now, but the basic principles of thermodynamics relating to turbocharging still hold true. Also, the intake manifold on the ahu sits in very close proximity to the exhaust manifold and turbo, so it gets exposed to a lot more than ambient temps.

Click to expand...

How about these data:
Small down pipe = higher velocity, greater restriction and less power.
Large down pipe = lower velocity, lower restriction and quicker spool.
I read Corky's book back when he wrote it about 10 years ago.
And since you mentioned it, let's see the data supporting ceramic coating the IM.

flee said:

How about these data:
Small down pipe = higher velocity, greater restriction and less power.
Large down pipe = lower velocity, lower restriction and quicker spool.
I read Corky's book back when he wrote it about 10 years ago.
And since you mentioned it, let's see the data supporting ceramic coating the IM.

Click to expand...

I'm sure there is data out there somewhere if you really want to find it. What degree of performance improvement one gets from wrapping the downpipe or coating the intake manifold I don't know- and surely is very situation dependent.
Hotter exhaust gasses are less dense (than cooler gasses) and offer less resistance. The end result is lower emp and better spool up. Despite being 20 years old, Maximum Boost is still a great read.

Here is a brief history of turbochargine the auto engine:

http://www.mre-books.com/turbo/history.html

That will lead you to this book by Hugh McGinnis:

https://www.amazon.com/Turbochargers-HP49-Books-Spark-Ignition-Applications/dp/0895861356

This is the 1987 edition. There is an earlier version I like better.

Hugh McGinnis was the Chief Engineer of Rajay (now Garrett) and worked with Chevrolet on the development of the turbocharged Corvair engine.

Here is a link to an Ebay sale for a factory MazdaSpeed 3 turbo heat shield. Just an example of a factory solution. This should keep the heat in the turbo and away from the intake.

Cummins Wrap their Downpipes on Euro 6 engines to get the DPF to regenerate less, or at least they did on test beds.

What that would mean for performance is unknown.

I've ceramic and other heat insulation coatings but not had back to back tests to see any real gains.

flee said:

As far as coating the intake manifold, you'd be better off insulating it from
the cylinder head since that's where the added heat is coming from.

Click to expand...

phenolic is the word for it. google "phenolic manifold spacer 8v vw" for bunch of examples.

the point is to stop the intake from getting heat soaked by the cylinder head by breaking contact and as such, conductivity of heat. cool idea, no pun intended, but wont fit in my situation with a high mount turbo on AHU.

keep the hot bits hot and the cold bits cold... those spacers and turbo blankets/down-pipe wrapping is cheap to try out at least.

Ryan,

Do you have any examples of what you have tried? I think we all agree there is value, but we don't know what the best bangs for the buck are here for the 8V and 16v TDIs.

For example, the phenolic manifold spacers for tdi put the exhaust and intake manifold really close together. The more we reduce that air gap the hotter the intake manifold will get from the exhaust manifold and reflective heat. The hottest things are:

1. Turbo
2. Exhaust Manifold
3. Turbo Downpipe

I'd say the head and the intake follows in some order. I'm not sure how you can really insulate a cylinder head for a daily or street strip type car. Some race teams do ceramic coat exhaust runs, valves, and head bowl areas, but I haven't found any papers that outline the effects of doing so.

Anyone interested in building out the list above with some testing and then maybe seeing about itemizing actions to correct them? (I covered the turbo one above)

Some digging:

TDI thermal spacers (no data): http://forums.tdiclub.com/showthread.php?t=468032

And a link to a 1.8T thermal spacer Data experiment. http://public.fotki.com/ttschwing/ma...ting_phenolic/

A sheet metal shield should do most of the shielding you want/need for very reasonable work/price. Also the solution auto makers rely on most often.

I like the KISS principle!

john.jackson9213 said:

A sheet metal shield should do most of the shielding you want/need for very reasonable work/price. Also the solution auto makers rely on most often.

I like the KISS principle!

Click to expand...

Thats just a barrier to the heat it doesnt actually keep it in the exhaust. Hot exhaust flows faster than colder exhaust. You want the highest exhaust velocity possible before you start creating too much of a restriction.

Coating the piston tops, combustion chambers, valve faces and exhaust ports would yield a good benefit as well. Keep more of the heat in the cylinder make more power for the same amount of fuel. F1 goes insane with thermo-efficiency if you're looking for ideas do some digging on some serious engineering forums. The info is out there but it can be kinda hard to find.

Ive actually started thinking about building a double wall intake pipe that I can seal and pull a strong vacuum between the sections and that should eliminate alot of heat transfer. Idea came from my coffee cup that I can pour boiling coffee into and not even feel the exterior of the cup change but a couple degrees, then still burn myself on the coffee 2-3 hrs later

running a turbo blanket on my vanagon with a gt2052 wastegated turbo ... can't speak for any performance gains but it did reduce engine compartment temps quite a bit

I'm in for more information.

I didn't do any coating on the head, valves, manifolds or my turbo, because it's not a race car and i'd like to limit feature/spec creep. I think with my build, a bit more insulation is in order to help the intake temps, heatsoak and some radiating heat. Something reasonable to help protect the firewall and intake pipes from excessive heatsoak.

I am going to look into an intake spacer though. Thanks for the info in advance, guys!

Dirtracr95 said:

Thats just a barrier to the heat it doesnt actually keep it in the exhaust. <snip>

Click to expand...

Should have been more clear than I was. Sheet metal shield was to keep turbo heat away from intake manifold. Not retain heat in turbo.

Agree with your comments.

About thermal coatings for the head and inside exhaust ports:

Oldpoopie has done this in one of his engines. I asked him a while ago about it, he could not say it made much difference. Granted, it is a 1/4 mile drag car.

For a daily driver/hot street car - there is a point where costs go straight up for Very marginal gains. Mostly bragging rights! I am seeing that right now with my Jeep/TDI conversion. It is a slippery slope!

john.jackson9213 said:

Should have been more clear than I was. Sheet metal shield was to keep turbo heat away from intake manifold. Not retain heat in turbo.

Agree with your comments.

Click to expand...

This is mainly for heat that's radiating from the turbo, correct?

john.jackson9213 said:

About thermal coatings for the head and inside exhaust ports:

Oldpoopie has done this in one of his engines. I asked him a while ago about it, he could not say it made much difference. Granted, it is a 1/4 mile drag car.

For a daily driver/hot street car - there is a point where costs go straight up for Very marginal gains. Mostly bragging rights! I am seeing that right now with my Jeep/TDI conversion. It is a slippery slope!

Click to expand...

That was part of the reason why I didn't do it. I'm sure it would help, but it wouldn't be cost effective for a daily car. All these little things do add up to benefit the total gains, but I do have to keep an eye on the cost and feature creep.

Yes, to keep heat radiating from the turbo away from the intake manifold.

Read somewhere on the web, this gets rid of 90% of the heat problem. Has to be why the car companies use it. Does the job and is cheap.

Here is a master Thesis written on the subject in 2014. Technical read.

Keep in mind it is in regards to combustion chambers.... maybe a new thread is needed..

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwjM1fTBnq_TAhXF44MKHfk2ADkQFghaMAk&url=http%3A%2F%2Fwww.diva-portal.org%2Fsmash%2Fget%2Fdiva2%3A759397%2FATTACHMENT01.pdf&usg=AFQjCNF9hTyQULgJ275NQ2eAlILLmiDI5w&sig2=aKTcZouUCTy4DEmrzl-fbA

Summed up.. In a diesel application heat losses to the oil and coolant are minimized (+)

On the down side (-).. the only down side.. it says the efficiency of the motor is reduced because it reduces the speed of the combustion process.

I wonder if that can be taken advantage of with timing.. Cetane is a rating for combustibility...or how easy it burns, Octane is gasolines resistance to burning. Higher octanes allow more advanced timing to take advantage of the longer burn event.
Normally we want higher cetane for easier ignition to optimize the timing in place. lower cetance is slower burning and less efficient as the testing shows to be the case with thermal barriers... or is it with timing maximized for it ??

john.jackson9213 said:

Yes, to keep heat radiating from the turbo away from the intake manifold.

Read somewhere on the web, this gets rid of 90% of the heat problem. Has to be why the car companies use it. Does the job and is cheap.

Click to expand...

My Audi(2.7T) had those on the downpipes from the factory, but I don't recall seeing that on my TDI cars. Did we get them around the turbo on the ALH cars?

I didn't happen to notice it on 99.9% of the tdi builds that i've looked at so far. The exception being just a couple extremely modified drag cars. I'm also noticing that hood vents are not present on upgraded TDI cars. Now, that is possible because there's no issue with air stacking on the MKIV platform. I'd still like to find out more about heat soak. My white car is only lightly modified, but I was keeping an eye on the intake temp using my ScanGaugeII and I did notice a difference of around 22 degrees between sitting at a light and then starting to move. No extreme or even spirited driving, reasonable acceleration, driving around 55mph on local roads. I do not recall ambient temps, but it was during summer last year. I'm definitely going to need to be more mindful of these figures during this summer driving my wagon(once it's completed) and see if a phenolic intake spacer makes a difference.

All Stock said:

Here is a master Thesis written on the subject in 2014. Technical read.

Keep in mind it is in regards to combustion chambers.... maybe a new thread is needed..

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwjM1fTBnq_TAhXF44MKHfk2ADkQFghaMAk&url=http%3A%2F%2Fwww.diva-portal.org%2Fsmash%2Fget%2Fdiva2%3A759397%2FATTACHMENT01.pdf&usg=AFQjCNF9hTyQULgJ275NQ2eAlILLmiDI5w&sig2=aKTcZouUCTy4DEmrzl-fbA

Summed up.. In a diesel application heat losses to the oil and coolant are minimized (+)

On the down side (-).. the only down side.. it says the efficiency of the motor is reduced because it reduces the speed of the combustion process.

I wonder if that can be taken advantage of with timing.. Cetane is a rating for combustibility...or how easy it burns, Octane is gasolines resistance to burning. Higher octanes allow more advanced timing to take advantage of the longer burn event.
Normally we want higher cetane for easier ignition to optimize the timing in place. lower cetance is slower burning and less efficient as the testing shows to be the case with thermal barriers... or is it with timing maximized for it ??

Click to expand...

Thanks for posting that! I hope I have enough brain capacity to read through and absorb that.

Thank you All Stock, That is a good paper and a perfect place for it is this thread. I think the overall discussions of thermal barriers is indeed relevant.

In the study they took the piston crown as the location that they were testing (50% theoretical heat loss is through the piston).

It would be great to have Dave (if he is free) to weigh in here. if we increase compression ratio .6 and decrease the thermal efficiency due to the coating, might we be at a net zero effect for efficiency?

I noted a raise in EGTs also, which in my eyes is a good thing.. that means more heat to spool the turbo.

I also thought more heat to spool the turbo would be the best part of thermal coatings.
But then I wondered what would that extra exhaust gas temperature do when going up a long mountain climb with a trailer?? As in overheating the turbo?

If you keep Software limiters below the turbos max. temp. limit, then not.

If you keep Software limiters below the turbos max. temp. limit, then not.