save the whales... save your MOTOR chapter two
 

here's a pretty common site under the hood of a typical FD in the year 2010...

http://img46.imageshack.us/img46/6326/to4z.jpg

a non factory turbo. done right it is a win win of course. done wrong it is a succession of blown motors.

how many times have we heard the story of a broken apex seal in the rear rotor housing. and there's lots of theories. some may even be true.

here's my theory and a fix.

note how close the turbine housing is to the front rotor's intake runners.

note how far away the turbine housing is to the rear rotors intake runners.

note that the turbine housing gets cherry red on the dyno where you get tuned.

note aluminum is very close to the top materials as to absorbing heat quickly and efficiently.

so you are on the dyno and you are progressively leaning the motor out. you are reading the number of O2 molecules zipping by the sensor in the downpipe. what you are reading is the average of both rotors.

your front LIM is very very hot from the radiance from the cherry red turbine housing. hot runners, hot air/fuel mix... not much O2 per volume as the molecules have expanded. rich.

the rear is considerably colder. relatively dense mixture w lots of O2. lean.

one rotor rich, one rotor lean... lets tune the motor up to 11.5 overall. what do you suppose the AFRs are in the front and rear at 11.5?

simple fix of course is a heat barrier and of course they are becoming more common.

do make sure you are, uh, covered.

oh, don't cinch it too tight. you want a half inch or so of air between the blanket and housing so you don't cook your turbo bearings at shutdown.

hc
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Well said Howard. Here's a plug for a quality solution, pictured is my engine bay:

http://www.turblown.net/store/index.php?productID=56

Also one of the reasons I've always liked the A-Spec long runner manifold is the placement of the turbine housing away from the block, relatively speaking :icon_tup:

http://www.turblown.net/store/produc...shield-Pic.jpg

Is it better to have the barrier on the turbo (ala turbo blanket) or on the LIM? I can never seem to talk myself into the LIM blanket with a turbo blanket already in place.

Wanna help change some minds? I'm sure I'm not alone in this situation.


.

I think Howard means to cover something. Either or Both. But cover one of them in order to lower the effects of the heat from the Exhaust Housing.

This is one of the things I plan to "borrow" from Rich's car. I like "some" of the lengths he went to in order to protect everything from heat. Some I will copy, others I may not. It's up to you bc it's your car. But protect as much as you can. It will help your parts, and your wallet.:icon_tup:

Definitely cover the turbine housing first and foremost. Then go from there :icon_tup:

Do you still indorse having the housing ceramic coated first? I know you at one point had yours done years back.

Also, I've been wondering if ceramic coating the intake manifolds would help or make it worse by slowing heat transfer out of a heatsoaked manifold.

Good point, but engines with the stock twins always seem to blow the rear rotor more often than the front, and the heat load with the twins is concentrated closer to the rear rotor than the front.

The one I've always heard is the intake manifold gives an unequal distribution of airflow where one rotor gets more than the other. I've also heard the rear rotor is hotter since the coolant flow through the engine is front to back and the rear rotor sees coolant that has already loaded with heat from the front rotor.

Regardless, heat shielding is always a good idea. Like the McDLT, keep the hot side hot and the cold side cold.

Dale

I have the stock heat shielding and everything is ceramic coated to boot.

ceramics, glass (fiber or otherwise) and mica come to mind as heat barriers.

my new manifold positions the hotside close to the the LIM purposely to gain advantage in other areas.

given the effectiveness of various heat shields i have zero problem as long as i can position what i want between the runner and turbine housing.

i was planning to use a secret weapon:

MICA.

i am told that zero heat can penetrate an 1/8 inch sheet of Mica. i had been using a shield of Stainless Steel which works to a point but MICA is in a whole 'nuther world.

maybe someone w a materials background would care to weigh in.

fiberglass wrap is quite effective and has been used primarily to wrap downpipes/exhaust. i have a suspicion it is related to MICA. the space shuttle of course uses some sort of ceramic bricks which, again, appear related.

my friend and co-conspirator on a number of items on my 2010 FD build, Cam Worth/Pettit, is sending me his Cool Power system. (http://www.pettitracing.com/rx7/a_coolpower.htm). Cam is pretty understated on a number of items on his site. while his single Cool Power setup look similar to others, (turbine cover, exhaust wrap and LIM shield panel) the actual material in the items is not a match. the material's family tree is firmly rooted in an extremely high tech operation based in Fl.

an uptick from the usual fiberglass wrap... (which i am not knocking, it works very well.)

it was Cam, BTW, observing an outside tuner dialing in a single turbo, observing the setup and concluding bad things were developing that sparked my premise for this thread. noting no heat shielding between the turbo and the front part of the LIM he found a piece of sheet metal and stuck it in between the turbo and LIM.

the motor immediately leaned out!

case closed.

there are many ways, besides sheet metal to get it done.

as i mentioned, i have a piece of MICA. probably 1/8 thick. position it between your manifold and turbine and you have fixed the heat radiation issue as far as the LIM.

there is a balance between completely encapsulating your turbine housing and cooking the bearings and not using any shielding. ideally you need a bit of airspace in the blanket.

another source of interesting heat shielding is Elliot White at Turblown. he has a high dollar spiffy inconel setup and also a nice blanket and shield.

here's the LIM heat shield.. http://www.turblown.net/store/index.php?productID=90

of course you can build it yourself. here's what i did in 2004 for my twin TO4 setup. it worked excellently. there is plenty of airspace but there is also a stainless steel shield around the turbine and a LIM shield.

http://img215.imageshack.us/img215/5...details004.jpg

let's see what you have built/bought.

howard

This is some really good information, is there any one specific turbine cover that is top of the line for a gt35R or similar turbo?

Both the version above and below have the same exact description but above looks different like is sewn to mold better and the one below looks like it's made with the reflective material and not the one above. I'm confused on which to choose, fit or reflective material. What are those studs for stocking on top of the one below?
http://www.turblown.net/store/produc...BRE500-375.jpg

Where do you get those reflective lower intake manifold boots?

post #2 and post #9





Mica is an excellent option. I've seen folks use it in various fire burning appliances - particularly in fireplaces and coal furnaces. It's also relatively cheap to purchase.

The water pump cools the front combustion chamber first, and then coolant flows to the rear. So the rear combustion chamber is not going to be cooled as effectively.

As for the LIM design, well the turbo 2nd gen cars don't have the LIM flow imbalance of the FD. They still blow rear rotors and the rear rotor still runs hotter. I have EGT logs which show this.

Ceramic coating $400
Turbo blanket $150
LIM blanket $250
Total $800

+ alky/water injection + vented hood + this + that...................

Besides power benefits due to cooler temps is there a study on how many miles the engine life is extended as a result of all these precautionary measures and $$$ spent? And how much is a reman engine instead? :) Just food for thought.............

I used to work in pcb manufacturing and one great material to use for thermal insulation was ceramic fiber paper. It is one of the key component in our thermal barrier design to prevent heat transfer of the hot load to the hugh alumimun presses. The ceramic fiber paper is flexible, easy to cut and shaped for used as insulation sheilding. It can be doubled up to whatever thickness you want and it is fire retardant. One of the thing to do is to sandwich the material in between two sheets of single sided reflective material, the reflective side facing towards the hot source (in this case the turbo) The reflective material used in pcb manufacturing was a high temp polyimide material with gold plated on top of a layer of copper. In the case of using it as a turbo sheild, we can't use polyimide because of the turbo temps but maybe just a sheet of metal with a super thin layer of gold plating on one side. Plating thickness does not matter, all you need is enough gold to provide a reflective surface.

I need some links to this fiber paper and mica.. please? subscribed..

I lost all my contacts when the company I've worked shut down and the IS department went around wiping out all sensitive data on the computers before I had a chance to backup my data.

But just did a quick google search and here are some info/specs on ceramic fiber paper in general.....super low thermal conductivity and extremely easy to work with.

http://www.ceramicfiber.net/ceramicfiberpaper.htm
http://www.infraredheaters.com/550-k.htm

here's what i am going to be testing. the pic (not my car) shows part of Pettit's Cool Power package. the heat shield, which is designed primarily as a barrier to the manifold has their trick material on the backside as does the turbo cover and panels for the tunnel above the exhaust

http://img442.imageshack.us/img442/2...lercoolpow.jpg

more info on it here:

http://www.pettitracing.com/rx7/a_coolpower.htm

if i have room for the MICA it will also be on board.

as far as spending $s on all this stuff... i made my own (post 9) for low dollars and it worked great. there's lots of ways to skin the cat. further, i think that viewed on the basis of heat reduction per dollar ceramic coating is a ripXXX. save your money. hey, it looks nice though.

let's see what you run.

as to post 14, i agree with it completely but it doesn't, in any way, rule out the turbine torching the front runners situation.

thanks to fd3rew for the ceramic fiber paper... i will, however, pass on the gold plating.... doesn't gold melt at low temps? at 1000 plus per ounce i will pass on it today.

The gold can withstand the temperature, I remember having alumimun brackets melt in press fires before any damages were done on the gold plated sheets. You only need a couple of microns of gold but yeah at like @$1100 or 1200 and ounce, it's hard to justify the cost benefit for this application and especially if you just want to test it out. The ceramic paper on the other hand is definitely feasible. It cost only a tiny fraction and you can make your own heat sheilding.

Now if you really want to go crazy, you want to be able to touch the sheilding when the turbo is glowing, you will need a steel honeycomb structure as an air gap (reduce conductive heat transfer) followed by the reflective material, a couple of sheets of ceramic paper, and then more reflective material and you can send this thing out to space and back...haha

Remember kids: heat is as much of a friend, as it is a foe...
 

Heat isolation is the key to turbocharged engines.

Keeping the heat in the turbine housing & reducing radiant heat into the intake is key here.

I'm interested in the statement that 1/8" mica is impervious to heat... I do not see how that is possible.

But before I cry wolf & say that is false, I will investigate.

I was thinking of adapting a semi-trucks turbo oil filter to the FD's turbo's oiling system (placed above the turbo's oil inlet, inverted & on the fire wall)

they are around .2 - .5 liters & when the engine shuts down, they drain oil through the turbo (cooling the bearings)

Also, wondering if the mica material can be tooled into a gasket for the LIM (to reduce heatsoak from the block)

if money is tight, I suggest grabbing the heat wrap from any reputable race supply store. I wonder if double wrapping has any advantages.

The blankets are very nice, but don't show oil leeks...

Oily turbo blankets can cause engine fires (along with neglect)

remember to remove the blankets & extensive heatshielding every now & then to inspect for oil leaks.

If money is no object, then swing for the fences (coatings, wraps, shields & blankets)

A VERY good point. Mine caught fire. I knew there was some leaking oil from the turbo (wasn't exactly sure where - thought it was an internal leak somewhere) but I never expected to see the blanket on fire when I popped the hood.

I'd definitely keep an eye on the blanket. I learned my lesson. :nod:

Well, I don't know why one is silver with studs other then that may be the reflective version but what are the studs for? I placed my order, so hopefully I get the black one that fits the GZ/Xcessive manifold.

The OEM's have been attacking this heat retention issue. The latest generation of new OEM turbo manifolds and n/a exhaust manifolds are usually some form of stainless steel. They use a dual layer design with an air gap to trap exhaust heat inside the piping in order to reduce engine bay temps and warm up the catalytic converter faster.

Taurus SHO EcoBoost twin turbo engine:

https://www.rx7club.com/attachment.p...1&d=1275436129

2010 Subaru Legacy EJ255 engine (factory twinscroll equal length turbo manifold):

https://www.rx7club.com/attachment.p...1&d=1275436129

Rx-8:

https://www.rx7club.com/attachment.p...1&d=1275436129

What does this or the previous thread have to do with saving whales?

;)

Kool-Aid

Thanks, good info. Makes enough sense to me!

For those of you running the turbo blankets, have you noticed a decreased lifespan on your turbos? Trapping the heat inside the blanket may be good for everything else in the engine bay, but I think that would cook your turbo pretty quick. I wish I had my textbooks here at home so I could put some numbers to it, but I know oil breaks down at high temperatures. I am not sure what sort of temperatures the turbo reaches with/without a turbo blanket, but it would be interesting to look into.

Has anyone tried taking cool air from the front of the car, running it over the turbos, and out the side vent of the car? This coupled with a heat shield between the LIM and turbos would keep heat away from the engine and provide the additional benefit of getting heat out of the engine bay rather than trapping it inside a blanket.

I've been running the same blanket going on 3.5 years now with zero turbo problems. Haven't removed it very often either, zero oil leaks.

The studs belong to the LIM that the blanket is wrapped around :D

I have the prototype LIM blanket on my GZ piece, and it's silver as seen in the picture I previously posted.

running cool air over the turbos would detract from their ability to make power.

Horrible idea (no offence)

80% of a turbo's power is from heat isolated in the hotside housing not from actual compression from the impellers

TURBOS ARE A WEARABLE ITEM

There are 2 main issues that people need to understand about turbos, to understand their wearable nature.

Bearing failure

Impeller Erosion

Both of which are possibly increased with higher boost & when increased heat isolating barriers are put into play.

Just like your apex seals and rotor housings, brake pads and rotors, tires and fuel filters...... Did somebody state that turbos last forever :confused:

No offense taken, just throwing ideas out there. Prometheus, would you mind shooting me a PM explaining how turbos get their power from heat isolation in the hotside housing? This is something I hadn't heard of and definitely want to learn about.

"thermal conductivity, k, is the property of a material that indicates its ability to conduct heat."

you'll note MICA doesn't have mucho K...

the bigger the number the more heat is transferred:

Aluminum alloy 180-120

Steel carbon 43

Stainless steel 12-45

Mica .71

Fiberglass .04 (but resin melts approx 1000F)

http://img541.imageshack.us/img541/6138/002mqm.jpg

my 1700-1900 degree propane/air flame only heated the opposite side of the MICA to 320 F. in addition, the panel was ambient (66 degrees) less than 2 inches from the flamepoint on the reverse side.
mica melts at approx 6000 F.

^ oooh, blow torch resistant. :cylonA:

Oh ok, thanks. hey wait, wasn't that your engine in the pic? I can tell cause of the huge DP. That is the black colored blanket? :scratch:

Hahaha no way...just read the 2 pages and this has been my theory since day one. makes no sence to put a hot hunk of iron next to a hunk of aluminum that needs to be cool. Now i will post what i use. its lagit poo
https://www.rx7club.com/showthread.php?t=906307...just a recent thread i started....and this idea howard has here has been applied

There are three different blankies in question here......

black=turbine
silver=LIM
light blue=Linus

https://www.rx7club.com/attachment.p...9&d=1275530702

Nobody said they last forever, but people tend to think they last much longer than they actually do.

I just put that in caps to emphasize the idea of having to replace/ rebuild the turbo/ turbos, before they get fragged from introduction of foreign media.

Thermal conductivity of some ceramics get very close to that number (W/mK)
http://www.matsceng.ohio-state.edu/f...eThCondJMR.pdf
http://www.accuratus.com/zirconia/zro2_thermal.html
As far as the advantage of mica over ceramics, I don't think there's much in it. How does the durability of mica stack up to ceramic and how easy is it to apply? There are countless vendors who do ceramic coating at relatively low cost, who the heck does mica coating of exhaust components?

This is one of the things my welder and I considered when it came time to make the manifold for the Holset H1C swap. Also we made a heat shield out of inconel that was attached to the front of the block off plate on the LIM. Howard, what is your opinion on the position and type of block off used to combat this heat? I plan on putting a stainless steel shield around the turbine as well here in a few days.

http://i834.photobucket.com/albums/z...eturbocopy.jpg

^ Looks professional, I'm diggin it....never cared for the blankets, they don't wear very well, and, as others have said, if they get oil soaked they're a fire hazard

excellent write up as always howard. i'm interested to see where we go with this thread. subscribing.

A few more relevant figures for your list:

Air .024 (illustrating the importance of heat shields & air gaps)

Cast Iron 55 (or less, composition dependent)

refractory mineral fibers .04 (aka rock wool)

high performance refractory ceramic fiber--typically <<1.0


A couple of notes:

Adding a blanket will not necessarily make a component run substantially hotter; what it will do is dramatically reduce the egress of heat as transfer slows down dramatically as the temperatures approach equilibrium. It tends to promote uniform temps throughout the casting and slows the rate of cooling which are good for the stability and life of a casting. If you can keep the oil & bearings cool enough, then there is no drawback to insulating the hotside.


For good thermal control in a managable pakage, I agree with the approach you've outlined. A hotside blanket and an external heatshield; I would suggest lining the heatshield with a thin (1/16") refractory ceramic cloth facing the hotside.

Where'd you get a piece of mica that big?

A proper turbine blanket works extremely well, and the benefits far outweigh any supposed 'risks' in my opinion.

They last for many years and, and anyone that worried about a fire hazard probably owns the wrong car.

We install/recommend them on every single turbo car that comes out of our shop if that tells you anything :)

i like it :)

if anybody cares and i can't see why they would but just to give a sense of my drift... i think a well designed turbine housing cover (blanket sounds too bedroom, we are talking engine compartment w gonzo hp) featuring some air gap is an essential part of the setup. i like barrier panels too. i plan to incorporate a panel that shields the primary runners on my CPR turbo manifold as well as the turbine housing.

i have an upcoming 4 turbo multi day dyno program (https://www.rx7club.com/single-turbo-rx-7s-23/separating-fiction-reality-couple-days-dyno-903611/) and will be doing a bit of heat r&d during the tests.

i suspect a lot may come from this thread as far as heat management. there certainly are lots of members that have come up w their own ideas. i hope to see some.

the mica was donated to the cause from a friend but McMaster Carr sells a good sized 1/8th plate of MICA for $61. cheaper than a blown motor. BTW, MICA may or may not be the answer... i am just peddling along here in hopes of learning a few things.

the thing that most impressed me about the MICA sheet was that it was totally ambient (66 F) less than 2 inches from where i had the 1700+ flame on the backside!

that tells me it just doesn't transfer heat. transferring heat away from the heat point should be no different than transferring heat thru the material to the other side which is our consideration.

i haven't (yet) put a saw to it but it appears to be workable.

hc

So on the turbo blanket, you want it to be loose fittiNg with an air barrier between?

glad i found this thread! i want to do some heatshielding soon... ^^ like what he said above, to properly heat shield there has to be a gap of air between the layers?

how easy is it to flex the MICA?

and some more good info in a howard thread.
I need to go play in the garage this weekend

Real thin sheets of mica can be cut with regular scissors. Thicker piece can be sawed - maybe snipped. They also make lampshades and stuff outta mica sheets. It's pretty workable.


Thanks for the info on where you sourced it at. All the sheets I found were very small and very thin (which would mean layering - and then you get into a "what type of adhesive" discussion). Thanks, HC!