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Current/previous twin turbo FD track guys I need your help

Old 05-20-13, 12:15 PM
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Current/previous twin turbo FD track guys I need your help

Iím reaching my wits end with the issue Iím having on my car. Iím losing money on track days I canít finish due to the car breaking, and I have to devote all of my spare time to trying to fix the car constantly. The full long story is below, cliffs are that I keep blowing out the bigger of the 2 gaskets between the manifold and turbine housings when run at the track and canít find an acceptable solution to keep them working.

Over the past couple of seasons Iíve had an issue with the exhaust gaskets that are in-between the exhaust manifold and turbine housings blowing out/melting. The first time I remember having an issue was when I changed out my turbos due to them blowing oil and smoke. While everything was going to be down, I had the turbine housings and exhaust manifold ceramic coated with 2000 degree coating (which was quite nice) to help keep heat down in the engine bay. I put everything back together and used pineapple racing aftermarket exhaust gaskets for the ones between the manifold and turbine housings and downpipe gasket to save money (reusing stock block to manifold gaskets as they were newer and in great shape). I also used new exhaust studs from McMaster Carr which are black-oxide and rated for 125,000 psi and copper exhaust lock nuts to hold everything together. I bolted everything back together and it ran great on the street. I took it to the track and one of the Pineapple graphite exhaust gaskets melted during the first day at the track. I took everything apart and saw the melted gasket and figured that the Pineapple gaskets werenít appropriate for my application with high heat for long periods of time. I also have a full 3Ē exhaust with a midpipe which does create a lot of backfires on the track and people say that the Pineapple gaskets donít hold up well to those conditions which is fine.

The next step was to put the same setup back together with factory exhaust gaskets throughout, new studs, and new lock nuts along with lock washers. This time it made it 2 track days (days, not full weekends) before the gasket blew out. I tried replacing the gaskets again and torquing everything as absolutely tight as I could along with nord-lock washers to ensure that nothing is loosening up while on the track causing the leaks. This ended similarlyÖthe same gasket kept blowing out which was the larger of the 2 gaskets that goes between the manifold and turbine housings.

Over this past winter I tore everything down again and had the exhaust manifold and turbine housings milled completely flat on their gasket surfaces because they had warped at some point which I believe was contributing to the issue. This workedÖto an extent. I was able to make it a full day at the track without the gasket letting go. However, I recently tried to complete a full 3 day weekend at the track and the gasket let go at the end of the first day. I had an older set of iron non-coated housings and manifold that I tried to throw on with new gaskets to get the car back on the track, but they leaked even worse than the ones that had just let go! Completely frustrated I accepted that I had lost the rest of the weekend that I had paid for.

I have another pre-paid track day in 3 weeks that I would like to attend and have the car survive without problems. Iím giving up on the coated manifold and housings as I know even after I milled them that they warped and caused a gasket issue anyway. My next solution is going to be to have the stock iron housings I have milled flat and use factory gaskets.

I could really use some insight from people that have heavily tracked stock turbo FDs before and possibly run into issues like this before. Here are some of the questions Iíve had:

ēIs the ceramic coating keeping so much heat in the manifold/turbines that itís warping them faster somehow? I thought initially that the coating left the gasket surfaces uneven, but they were milled flat to remove that argument.
ēAre the aftermarket studs and nuts not acceptable for track use? Are they stretching and opening up the gasket area for blowby? Do I need to go back to the stock inconel stuff? Itís expensive, but would be worth it if it was an actual solution.
ēShould I look at an alternative gasket material? The stock gaskets are multi-layered steel and seem like very robust pieces, but should I try to make custom ľĒ thick copper or something similar?
ēShould I be trying to torque them even more? Iím basically putting them as tight as you can get them with a standard 3/8Ē ratchet (probably 70-ish ft-lbs). I can get a 3/8Ē breaker bar in there, but not likely anything ĹĒ

I realize that many will point to the solution to this problem being that I should go single-turbo and get rid of the twins. Itís a viable solution, but Iíd like to avoid throwing many thousands of dollars at a problem of blowing out $100 in gaskets. Additionally, I donít really NEED any more power than I have now and I know that single setups can have their own issues on the track.

For reference my current motor mods are: Aluminum intakes, PFC, 850x4 injectors, 3" downpipe, 3" midpipe, older Tanabe Medallion exhaust which is 3" but necks down to 2.5" right at the downpipe for about 2" in length which helps keep the boost under control. 12-13psi boost pressure. Fluidyne radiator and dual aftermarket oil coolers. Water and oil temps are fine on the track (95C or less water temp during 30 min session).
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Old 05-20-13, 12:20 PM
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I would check my trailing ignition system.
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Old 05-20-13, 12:39 PM
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+1 on the ignition, i've never seen an FD blow a turbo gasket, like that, although its really common on other cars.

i'd make sure all the gasket surfaces are clean and flat, use whatever studs and nuts you like, but i'd use the factory torque spec, too tight might make it worse.

my friend had this problem, and it turned out to be that the land for the nut on the turbine housing wasn't perpendicular to the stud, the FD turbos aren't chinese so this is a little out there but you should check anyways.

i would also use new Mazda gaskets between the turbo and manifold.

you also might want to check the exhaust backpressure.
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Old 05-20-13, 01:15 PM
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Originally Posted by BLUE TII View Post
I would check my trailing ignition system.
Originally Posted by j9fd3s View Post
+1 on the ignition, i've never seen an FD blow a turbo gasket, like that, although its really common on other cars.
I honestly hadn't thought of that at all, are you saying you think the ignition is making EGTs too hot and burning things up? I'm currently running stock FD coils, NGK wires (new last year), and NGK 9 heat range plugs leading and trailing. I tested the coils before this season (Ohm test from manual) and they were fine. The plugs are maybe 1000 miles old. I've never had a breakup or other issue to lead me to believe there's a problem with the ignition. Could I be missing something? Would running colder plugs really alter EGTs significantly?

Originally Posted by j9fd3s View Post
i'd make sure all the gasket surfaces are clean and flat, use whatever studs and nuts you like, but i'd use the factory torque spec, too tight might make it worse.

my friend had this problem, and it turned out to be that the land for the nut on the turbine housing wasn't perpendicular to the stud, the FD turbos aren't chinese so this is a little out there but you should check anyways.

i would also use new Mazda gaskets between the turbo and manifold.

you also might want to check the exhaust backpressure.
I've been using Mazda factory gaskets for the last 3 attempts, I only tried aftermarket once and never went back to that. I'm sure that exhaust back pressure is pretty high with the stock manifold/turbine setup (I'm still sequential), but I don't see any easy way to get around that.

The first couple of times I torqued everything to factory specs (which I thought was on the lower side like 45 ft-lbs if I remember correctly, and thought maybe that lower value was allowing things to expand too much under the heat, but do you think I can really cause cast iron to warp by cranking the nuts too tight?

To also add to my current setup that I forgot, I run a coolingmist water injection system running about 350cc of water as insurance (not tuned). I run thru about 3/4 of a gallon of water in a typical session, but I think if anything that's supposed to help keep EGTs down.
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Old 05-20-13, 05:18 PM
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Gasket leak

I had the same problem. However; mine was due to a warped exhaust manifold. I run sequential BNR's on a stock manifold with a rack mounted external solonoid kit (which is awesome BTW). You should PM Fritz and see if he has another exhaust manifold. Get new stock studs, nuts, and washers along with the new stock manifold to turbo gaskets. Use NeverSeez on all studs and bolts. Get the torque specs for all studs; the two smaller studs at the bottom are a lower torque and I'm guessing that if you over-torqued them, that's your issue. You can also thinnly coat the gaskets with NeverSeez on both sides prior to install. It will fill small gaps until the carbon deposits can provide a complete seal. When you start to snug up the nuts/bolts, start at the middle top to middle bottom and work your way toward each end of the turbo.
Just take your time and lightly hand tighten 2-3 times in the sequence as just described. Once your certain your getting close to being "snugged-up". Get out the inch-pound torque wrench and tighten in the same pattern. Check torque in sequence described until everything "clicks". Until I went back to the stock bolts, nuts, etc. I had the same problem. At $90 a pop for that one gasket, I was getting damn tired of putting Ray Crowes' kids through college...chuckle. Call Fritz and Ray and get all the right stuff along with an inch-pound torque wrench and I believe you'll be in business. Cheers!
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Old 05-20-13, 05:20 PM
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P.s.

I'm a "Track Rat" too. Just got back from VIR last night. Hope this helps.
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Old 05-20-13, 08:27 PM
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Oddly enough, I have a small exhaust leak somewhere near the motor/turbos also. It started shortly after installing ceramic coated exhaust manifold and has been slowly getting worse. I never had an issue with the uncoated manifold in all the years that I tracked my FD on sequential twins...

Another coincidence, I am also getting some odd backfiring....


Can someone share more info on this trailing ignition suggestion? WHat is the problem you guys have seen?
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Old 05-21-13, 07:48 AM
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Dave thanks for the information, it sounds like stock hardware and torque specs are the next step to try.

Gracer7, that's a bummer to hear...pretty much exactly what I went thru. It will start as a small leak, but at one point it'll blow out on track and then there's nothing that can be done. Once mine goes and it won't build full boost anymore and I know that I need to stop before doing more damage. I was skeptical as to if the ceramic coating was causing issues, but the only reaonsalbe explanation I can think of is that it made the gasket surface uneven.

I do have a lot of backfires when letting off throttle on the track, but that doesn't seem to be anything new. It'll shoot like 2 feet of flame out of the tailpipe, but I also have a fully open exhaust. Nothing has changed in my iginition setup over time, and I believe my coils are still good. None of the other gaskets in the exhaust seem to be bothered by the back firing and I'm running remflex type gaskets for everything post-downpipe.
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Old 05-21-13, 08:14 AM
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Originally Posted by Dave McLaughlin View Post
I had the same problem. However; mine was due to a warped exhaust manifold. I run sequential BNR's on a stock manifold with a rack mounted external solonoid kit (which is awesome BTW). You should PM Fritz and see if he has another exhaust manifold. Get new stock studs, nuts, and washers along with the new stock manifold to turbo gaskets. Use NeverSeez on all studs and bolts. Get the torque specs for all studs; the two smaller studs at the bottom are a lower torque and I'm guessing that if you over-torqued them, that's your issue. You can also thinnly coat the gaskets with NeverSeez on both sides prior to install. It will fill small gaps until the carbon deposits can provide a complete seal. When you start to snug up the nuts/bolts, start at the middle top to middle bottom and work your way toward each end of the turbo.
Just take your time and lightly hand tighten 2-3 times in the sequence as just described. Once your certain your getting close to being "snugged-up". Get out the inch-pound torque wrench and tighten in the same pattern. Check torque in sequence described until everything "clicks". Until I went back to the stock bolts, nuts, etc. I had the same problem. At $90 a pop for that one gasket, I was getting damn tired of putting Ray Crowes' kids through college...chuckle. Call Fritz and Ray and get all the right stuff along with an inch-pound torque wrench and I believe you'll be in business. Cheers!
I got your PM but Dave gave you all the answers if you need the manifold please let me know. I also have a NEW complete gasket set.

Originally Posted by Dave McLaughlin View Post
I'm a "Track Rat" too. Just got back from VIR last night. Hope this helps.
Dave,
Good seeing you but sorry we didn't hang out more.
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Old 05-21-13, 08:17 AM
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Originally Posted by gracer7-rx7 View Post
Oddly enough, I have a small exhaust leak somewhere near the motor/turbos also. It started shortly after installing ceramic coated exhaust manifold and has been slowly getting worse. I never had an issue with the uncoated manifold in all the years that I tracked my FD on sequential twins...

Another coincidence, I am also getting some odd backfiring....


Can someone share more info on this trailing ignition suggestion? WHat is the problem you guys have seen?
Ceramic coatings are a joke a rotary car that is seeing track life. They'll flake off in about 2 week ends when pounded on.
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Old 05-21-13, 08:39 AM
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Thanks Fritz. I'm having my current manifold and turbine housings milled flat so that I can "start fresh" with them.

Surprisingly the ceramic coating I have on the components has held up quite well (it was offered by a vendor here) and I've been impressed with it. But do you see any reason it would be leading to my issues?
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Old 05-21-13, 09:33 AM
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Originally Posted by Fritz Flynn View Post
I got your PM but Dave gave you all the answers if you need the manifold please let me know. I also have a NEW complete gasket set.



Dave,
Good seeing you but sorry we didn't hang out more.
Fritz,
Good seeing you too. Between students, rain, and bad timing, sometimes it's hard to cover everything. How did the South Course thing go on Monday?

Cheers!
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Old 05-21-13, 12:29 PM
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I honestly hadn't thought of that at all, are you saying you think the ignition is making EGTs too hot and burning things up?


Can someone share more info on this trailing ignition suggestion? WHat is the problem you guys have seen?


That is the condition that would cause these symptoms on a stock RX-7, and we see it a lot so we are just throwing it out there in case it was overlooked.

On the trailing ignition a bad connection between plug and wire, bad wire, bad connection at coil or burnt out coil is quite commonly missed as the car will run fine, just be down a tiny bit on power and start having reliability (and emission) issues stemming from the high egts of post exhaust port combustion. It often leads to overrunning on decel and popping at idle as well.

It sounds like you guys have that covered.

Perhaps the ceramic coating causing excessive heat may be the right venue to pursue on this issue. Time to take a survey of ceramic coated twins users on exhaust leaks.
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Old 05-21-13, 12:56 PM
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I'll take a look at the plugs/wires to make sure there aren't any loose connections. Do you think that running colder 10 heat range trailing plugs at the track would help or make a difference?
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Old 05-21-13, 01:26 PM
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Go with factory studs, gaskets, and nuts. The factory jet nuts are inconel. Don't assume OEM is substandard. Fritz taught me that.
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Old 05-22-13, 12:04 PM
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I'll take a look at the plugs/wires to make sure there aren't any loose connections. Do you think that running colder 10 heat range trailing plugs at the track would help or make a difference?

I would always run a colder plug on the track to help guard against pre-ignition when you are pushing the thermal limits of all vehicle systems.

As long as it is a stock style surface discharge plug. I have had bad luck with ground straps melting off during detonation on traditional "piston engine" style plugs.

I wouldn't think that the heat range of the plugs would make any difference with the gasket problem you are having, unless it was the extreme heat of detonation causing the failure, but I don't see how your engine could survive this for such an extended period.
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Old 05-23-13, 04:44 AM
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I've been chasing the exact same issue for the last 12 months, eventually deciding to just race with an exhaust leak at the last race meeting. I've taken most of the same steps, milling, new gaskets, studs and nuts etc.

I came to the conclusion that the 20 year old twins were never designed for racing and have just changed to a GT3540 set-up. Final bolt up tomorrow night then off to the track for a test day (Sat) and race day (Sun) next weekend. I'm not chasing more horsepower, just reliability so I can build up to some endurance events.

The one thing I would suggest (and i'll be doing the same myself next weekend) is to re-torque everything after it's been hot.
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Old 05-23-13, 04:10 PM
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Originally Posted by ptrhahn View Post
The factory jet nuts are inconel.
ah no wonder they are priced like they are inconel... JE10-40-355 for the 14mm head ones, and the bigger ones are wait for it, JE11-40-355.

any self respecting Mazda dealer will stock a bunch, they use em on just about every car
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Old 06-08-13, 12:49 PM
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For serious track guys, going single is the only way to go. The stock twins trap so much heat (small turbines packed in there tight). I recall when I went single years ago, my cruising vacuum went from 7" to 12", just to give you an idea how much easier the engine was breathing. Also everything else near/around your engine is getting baked to a crisp.

turbo rotaries are great, just got to keep them free-flowing and cool. You're right, you're pretty much at the end of your options when it comes to tracking your stock twins, issues will keep popping up with them. Just go with a well designed single system, you'll be much happier
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Old 06-11-13, 09:34 AM
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Got the car back together with the coated manifold and housings that were machined flat again with new gaskets and all new stock studs and nuts. I also changed to a Greddy SP exhaust which is a full 3" to get rid of any restriction in flow.

I did a single day event yesterday at Mid Ohio which I was limited to just an afternoon of running due to weather. I swore I heard the beginnings of an exhaust leak (could also be paranoid), but it didn't get worse or blow out at the event. I'm still of the mindset that its a matter of time before it lets go. At this point I believe the coating is the only variable left.

I have a set of non-coated housings and manifold being machined and I will use those next with new gaskets and the stock hardware. That will be my last test with the stock twins. If I cannot get better longevity out of that setup then ill put the car away until I can afford to do a single setup.
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Old 06-11-13, 10:28 AM
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The stock twins hold a lot of heat, and they need to breathe. I'm suspicious that the ceramic coating pushed them over the edge of their heat capacity in a race-environment.

I debated coating the manifolds, since engine-bay-heat is such a scourge for any relatively stock FD. But; given the anecdotes here, it seems there is more risk in frying the stock turbos by not letting them breathe.
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