Rotary Turbos and Turbo bags!

[RICE RACING]

So I changed out my turbo a while ago but never shared why I say turbo bags are a kuuuuunt @! on turbo rotaries, here is why....

Perfect tuning, egt never over 950deg C (front and rear same) on up to 36psi boost pressure, see EGT probes conditions after 3+ years and 30,000km of running at ~600bhp for most of this time

This is what will happen to a high nickel content turbine housing when insulated with a turbo bag! LONG TERM! I appreciate not many people in the rotary don't have the ability/skills to run cars at high power like I do and over multiple years and 10's of thousands of kilometers but so you don't have to read about it in a text book or some crack pot internet theory here is the proof from someone who actually has done this

Inconel turbine wheel fine, no housing warping, but very high degradation of the tangential divider and inner and outer surface of the turbine housing as you can see in pictures.

[chibikougan]

Shit'll buff out.

[RICE RACING]

Originally Posted by chibikougan

Shit'll buff out.

BDC'd

[Jwteknix]

Would u recommend a metal shield over and blanket?

[RICE RACING]

Originally Posted by Jwteknix

Would u recommend a metal shield over and blanket?

100% otherwise it's proven it will be BDC'd after sustained use at high power. Retained heat in the housing = what you see above, even if EGT is within normal limits.

Mind you I have done countless 300+km/h runs, extended high load tests (durability testing), regardless though, retained heat in the turbine housing will kill it long term.

A heat shield with an air gap is mandatory.

Blankets and the like are for dickheads and drug race cars that cant do shit except last a few seconds or some poof box with chrome stickers and 20" wheels lol!! not real mans cars I did this test to prove once and for all that those turbo bags are only recommend by useless kuuuuunts who could not be bothered to make a proper heat shield

[banzaitoyota]

Basic fluid flow and thermodynamics are your friend. The Naval Nuclear Power program drilled the basics into my thick skull over 30 years ago. Be interested to send a sample of that to the lab and see the actual damage done by heat soaking it.

[RICE RACING]

Taken this off the interweb, its not a bad explanation of the effects and what I found in this test

"Why Header Wraps Destroy Your Headers ... and *TURBO BAGS!!!*
Why Thermal Ceramic Coatings are Recommended

Regularly we are asked about, or have commented on the use of header wraps (header tape, thermal tape, heat tape). This issue is a real pet peeve of mine. Good or bad about a product I will give my opinion based upon direct use and fact, and this stuff screams "Do Not Use on Exhaust Headers!"

THE FACTS:

* Header wraps are designed to keep the heat in the header to improve scavenging of the cylinders. Keeping the heat in the header allows the exhaust speed to remain high. (the right idea)
* Header wraps, by keeping the heat in the header, also reduces the radiant heat in the engine bay.
* There are no header manufacturers that I know of that will warranty their headers if any header wrap is installed on their products.
* In most cases the header wrap damages the headers beyond repair. (I will explain below)
* If you run a lean mixture, you "may" see a slim performance gain using header wraps. A rich mixture may show slim to absolutely NO gain in performance.
* If you do not mind replacing your headers and header gaskets regularly, and you like that ugly look of a wrapped header, go ahead and use the heat wrap.

BACKGROUND INFORMATION:

In the past, almost all NASCAR and other racing engine builders and crew chiefs used header wraps for the added power gains and thermal control benefits offered by their use. Problems occurred when these same teams had to replace the headers after each race (NASCAR) due to the wrap being about the only thing holding each header together. Most engine builders, crew chiefs, and definitely the header manufacturers themselves do not promote the practice of installing these wraps directly on the headers! They now utilize the thermal coatings that are chemically and electrically applied to the headers. Popular header coating services include Airborn, Jet Hot, HPC, and some header manufacturers now applying the thermal coatings in-house.

Imagine having to replace a $1500.00+ set of headers after each race weekend! Few but the most financially well-off race teams can afford to do this. Also, consider the downtime in remaking a custom set of headers. Most custom header makers do not have copies readily available.

I believe that the wraps are good to protect various underhood 'items' from heat, but not for the use of holding the heat in the header. For example: you can use the wrapping for the protection of fuel and oil lines, wiring, covering a starter motor, etc.

Cool air needs to be around the header, and insulating it with a wrap to hold exhaust heat in makes the header material surface temperatures reach near molten levels. When you wrap the header you trap the heat in the header, but also suffocate the material that needs to breathe to dissipate heat for it's own survival.


Engineers, Metallurgists, and other experts out there will state that there is no way that the material can fail because it was designed to withstand the internal temperatures of exhaust gases. This is very TRUE! But, when the header is not allowed to cool (or breathe) so as to dissipate those extreme temperatures that the wrap is controlling, you have now developed a heat absorption that compares to thermal friction. This causes temperatures to continue to rise beyond the normal exhaust gas temperatures (EGT's) the header material was designed to withstand. This holds true as with most any type insulation.

Try this experiment the next time you launder a load of bath towels and then dry them. Immediately pull them out of the dryer and just toss them in a snug pile on your bed. Now leave them there for a many hours, even a day, and then open them. You will find that there is still a considerable amount of heat left in the center towels. This heat, even though the outer towels and bed are normal room temperature have been able to contain their heat. This is a simple thermal insulation test, but compared to your headers you have an internal heat supply constantly coming from the engine when running. The heat on the outside portion of the header material is trapped between the wrap, and soon will begin to fatigue the header. This build-up of heat is amplified by the wrap. Your freshly dried bath towels do not need to breathe, your header material does.

The EGTs stay the same but the properties of the header material changes by amplifying the temperature due to the insulation. This action goes against normal laws of thermal dynamics, but this effect is fact, and you have to pull the ears off most engineers before they believe you. This is the trouble with plenty of education, but a lack of something that is often just as important, that of "common sense"! If you decide not to believe these statements that is your choice. Go ahead and install the header tape on your headers ... we'll be happy to sell you a new header set!



HERE ARE A FEW TEMPERATURE READINGS TAKEN AT DAYTONA MOTOR SPEEDWAY:

Below are the test parameters and results using Jet-Hot Coatings® coated and uncoated headers:

(10 Laps; the same engine and car with identical headers; one header set is uncoated, one header is Jet Hot® coated. The engine is operated between 6,900 and 7,500 RPM, and temperatures are measured immediately after the last lap with the engine idling at 2,000 RPM with identical sustained EGT's of 850º F.)

MEASURED AT:

JET-HOT® COATED

NO COATING

COATED DIFFERENCE
1" from engine

300º F.

750º F.

- 450º F. Header Coating Benefit - Thunbs Up
2" above header port (on header)

210º F.

300º F.

- 90º F. Header Coating Benefit - Thunbs Up
1" above floor pan (in car)

115º F.

165º F.

- 50º F. Header Coating Benefit - Thunbs Up

Pretty impressive difference, and with any of these coatings you should take care to not damage the coating. The thermal coating becomes part of the header material. Most of the other coating brands are comparable to these figures (if they are multi-layer, inside and outside of tube applied and using proper materials).


SOMETHING ELSE THAT FEW RACERS and CAR OWNERS REALIZE:

Headers Oxidize!

Under normal use, and even more with higher EGTs and header surface temperatures, your headers will oxidize and small amounts of material is actually removed from the headers. This means your uncoated headers will become lighter and weaker over time.

Examine these actual test numbers:

* Mild Steel (1010) uncoated header exposed to continuous 1200º F. in normal air will have a weight loss percentage of roughly 25% with only 10 hours use at this temperature.
* Stainless Steel (410) uncoated header will have roughly 8% weight loss in the same 10 hour period.
* A coated mild steel header will have NO weight loss at temperatures up to 1200º F. In fact it will actually gain a bit of weight! Between 1300º F and 1600º F the coating will begin to show signs of mud cracking or like the look of lacquer checking. However, limited diffusion takes place between the coating and the substrate, producing a very thin film of iron aluminide, which continues to inhibit oxidation.

Header Oxidation Graph



Now, think about the information provided above and consider the added thermal stress generated by the header wraps. What do you see? Remember that the wrapped metal cannot cool properly and the header wrap is causing the material to super-heat and pre-maturely fail!

BASIC UNDERSTANDING:

Because of the expanding gases, if you have had the experience (as I have) to see first hand what header warp has done to a header, you would notice the locations on a header where the material failures occur. This is typically where a step would be, or where there is an expansion pulse of exhaust gases inside the header tube. I have had headers in my hand where literally the only thing keeping the header in one piece was the wrap. Whole chunks of the header material was gone, simply melted away. If you were to speak to most "engineers" (I use that title with caution) they will probably tell you that aliens stole the metal as the car was racing around the track! They say this because the conclusion that the wrap is causing problems is not part of normal metallurgy and thermal dynamics theory . The header wrap allows temperatures between the wrap and the header to turn the material molten.


IN CLOSING:

We know that header manufacturers will NOT WARRANTY a header which has had a wrap installed on it. We know that I (and many others) have personally witnessed, tested and inspected headers that have been destroyed after running headers wraps, and these headers were on a perfectly tuned engines.

Just because an item or product is advertised for a specific use does not mean it does not do what the promotion or advertisement states. But, it also does not mean it is the best choice either, or that there are negative consequences. We have all seen TV commercials on all of these "medical miracles" and "overnight diets" that do such feats as fast weight loss and re-grow your hair. How often have we laughed at the side affects, like the most common being penile failure. Oh sure, I want to take some drug if my hair starts falling out that makes other body parts fail to function. NOT !!! Those pharmaceutical companies can pucker up and kiss my backside! I'd rather have function than hair!

The same can hold true with automotive and marine products. Heat wraps are great, just do not use them ON the header. Use them on a device or component on your vehicle that you are trying to protect from header heat.

If you want a true thermal barrier that will reduce thermal loss in the header, reduce under hood temperatures, and make a few horsepower in the process, have your headers thermal coated by one of the many companies available or the header manufacturer themselves. Most all of the coating companies offer inside and outside, multi-layer coating as standard. DO NOT allow your headers to only be coated on the outside, or just a single layer application! This is not a complete or quality process.

*NOTE my EGT is perfect! pipes up to the turbine housing look like new as do the EGT probes* so 100% turnine heat bags FUCK your turbine housing!!!"

[GySgtFrank]

Good info. This has been my experience with header wraps as well. Headers rust away fast enough on their own if uncoated. Wrap them and they last maybe a quarter of the uncoated header lifespan. It's interesting that the same type of degradation can be seen with turbo bags. I would have thought the cast iron would have stood up to heat soaking better than that. Guess not, thanks for the heads up.

[RICE RACING]

Originally Posted by GySgtFrank

Good info. This has been my experience with header wraps as well. Headers rust away fast enough on their own if uncoated. Wrap them and they last maybe a quarter of the uncoated header lifespan. It's interesting that the same type of degradation can be seen with turbo bags. I would have thought the cast iron would have stood up to heat soaking better than that. Guess not, thanks for the heads up.

No worries, I always wanted to prove that TURBO BAGS are fucking shit, and as you can see they 100% are

I suppose like I said in my first post if you are a show pony or drug racer or generally some fagot who does not actually use the power of your car often then you may find that "nah man, bags are fine, never ever had a problem" you will only never have a problem if you do not use the power (I.E. Generate enough heat!@ consistently) to degrade the housing.

My last housing was a 1.00A/R twin scroll size, and it was on for a few thousand km until it became a restriction and I swapped it out, it ran a bag but because the power level was low and not as much true proper high speed testing was done it did not look this bad. It takes BIG POWER and repeated power after power runs to accumulate the "heat" in the housing and not let it dissipate to over stress the housing. (NOTE: one or two consecutive laps on a low speed track racing for a plastic trophy!! is not high stress LOL) Its just proof of how hard I run my set ups in the name of true proper endurance testing and in that environment BAGS are a KUUUUUUNT!

[silverfdturbo6port]

I've used bags and wrap n street machines for many many years with no issues. Even with drag racing, autocross and numerous 180+mph pulls on 100* days I've never seen them "BDC" nor myself turn into a "KUUNT" but those are not harsh conditions like a race car as stated by Peter.
But for a dedicated "Race" car I will guarantee you will see the effects like in the OP.
But for daily driving/street use and you want to keep the bay temps down then Bags, wrap, shielding, heat coatings all work great.

[RICE RACING]

Originally Posted by silverfdturbo6port

I've used bags and wrap n street machines for many many years with no issues. Even with drag racing, autocross and numerous 180+mph pulls on 100* days I've never seen them "BDC" nor myself turn into a "KUUNT" but those are not harsh conditions like a race car as stated by Peter.
But for a dedicated "Race" car I will guarantee you will see the effects like in the OP.
But for daily driving/street use and you want to keep the bay temps down then Bags, wrap, shielding, heat coatings all work great.

It's a function of power, restriction, retained heat, time used at high power.
Anyone familiar with FD3S twin turbo systems who has used them at high power (1.5bar boost @ ~400bhp or so) and over a huge length of time (say 50,000km+) will attest to the similar degradation of manifolds and turbine housings (non insulated!)

If you are making lower power, use it less frequently, have larger housings, turbo's etc all of this simply means you have less if ever any likely hood of seeing such things

*If you are making the power (with associated heat input!)
*Use it often and at high duration
*Even on a T4 platform with the biggest housing you can run and super low restriction outlet *see proven tests* you will fuck the housing if you insulate it... proven.

[silverfdturbo6port]

Im gonna fiddle with the inconel material on the 20b this time around. I like having my shit wrapped and bagged but they never last. They make a mess if you even touch it lol
I enjoy the hood temps tho .
I just need to find a source that doesn't rape me on prices bulk

[RICE RACING]

Will be keen to see how you go, keep us updated here on RCC

[silverfdturbo6port]

Will do!

[Slides]

Is there any truth to the claims that the material in the T4 housings is not as tolerant as that used in the GT turbine housings? Perhaps you would be better off with a GT4094 ?

I think I have seen pics like that in a few threads from T04z cars that have been circuit raced?