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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Sun Aug 19, 2012 9:06 pm 
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swedishmeatball wrote:
I have a 60 trim t3 and new supply line kit that I was going to use but no longer have a use for sitting in my garage in Calgary...


Sounds good I think... Still trying to do some reading and get up to speed on all of this so not sure exactly what you have but I'm all ears. :mrgreen: Incidentally, I found the article on making your 700/900 turbo go fast you have on your Telus site. Excellent resource, so far I'm getting the impression I can meet my power goals with a 12 or 13c, doing the exhaust and increasing the boost once everything is fine tuned. Turbo upgrades don't get discussed still Stage 3? From what I got from the article so far I'm leaning towards doing Stage 1 and see what it's like before going further. I already have part of Stage 2 with the 90+ manifold and the potential to chip my new ECU.

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Mon Aug 20, 2012 11:59 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Journal bearing turbos have play - you can't avoid it. So long as the blades aren't touching the housings, it's usually okay (though not ideal). I've run a few turbos with a lot of play and they don't use a considerable amount of oil. Do what you like, but I'd look elsewhere first (i.e., crankcase pressure). Again, the "seals" in a turbo DO NOT seal, they're there to inhibit leakage but they strongly depend on excellent drainage and less crankcase pressure than exhaust/boost pressure. It doesn't take much!

And a 12B is blowing a lot of hot air at 185 RWHP. It's what I had in my 740 on the dyno - chipped, 3" catless exhaust, otherwise stock B230FT. If that's what you run, don't expect a bunch more power than that. The 13C will have more exhaust backpressure than the 12B, so at a given boost pressure it's your choice between EBR and compressor discharge pressure. A 15G is a good step but even with a TD05H turbine I wasn't too impressed with it when I drove one, and it doesn't easily mate up to the 90+ exhaust manifold (3 studs or LOTS of grinding on the turbine housing). The Garrett that Athal's selling is a cheap & easy way to go, and I think he made ~210 RWHP on it?


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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Mon Aug 20, 2012 12:46 pm 
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Ugly Duck wrote:
Journal bearing turbos have play - you can't avoid it. So long as the blades aren't touching the housings, it's usually okay (though not ideal). I've run a few turbos with a lot of play and they don't use a considerable amount of oil. Do what you like, but I'd look elsewhere first (i.e., crankcase pressure). Again, the "seals" in a turbo DO NOT seal, they're there to inhibit leakage but they strongly depend on excellent drainage and less crankcase pressure than exhaust/boost pressure. It doesn't take much!


Matt, that's the feedback I'm looking for (and need), any assumptions I make are based on my limited experience. If you feel there's a crankcase pressure issue that's where I am headed next as part of my Stage 0, I was just happy to see even compression with no leakdown but I obviously have much to learn on how turbos seal and their relationship to the engine. In one of my earlier posts I commented on how "steamy" the dipstick tube looked when checking the oil, I haven't had any dipstick ejections but it does appear to be somewhat gassy on the crankcase side of things. With the compression numbers, lack of a leakdown, and the UOA showing no fuel dilution, crankcase venting would appear to be an issue.

Ugly Duck wrote:
And a 12B is blowing a lot of hot air at 185 RWHP. It's what I had in my 740 on the dyno - chipped, 3" catless exhaust, otherwise stock B230FT. If that's what you run, don't expect a bunch more power than that. The 13C will have more exhaust backpressure than the 12B, so at a given boost pressure it's your choice between EBR and compressor discharge pressure. A 15G is a good step but even with a TD05H turbine I wasn't too impressed with it when I drove one, and it doesn't easily mate up to the 90+ exhaust manifold (3 studs or LOTS of grinding on the turbine housing). The Garrett that Athal's selling is a cheap & easy way to go, and I think he made ~210 RWHP on it?


Not sure what you mean with the 12B comment "blowing a lot of hot air", it's not efficient/overworked? My goal numbers were at the crank so 185 RWHP would be in my 200-225 BHP range?

Can you explain what EBR and compressor discharge pressure is in relation to the 12B or 13C? I am guessing the discharge pressure is a function of the size of the hot side wheel? I found a thread on TB "Overlap & EBR", looks like it might take some time to read and digest based on a first glance. Good input on the 15G, I thought it was as simple as reclocking for RWD use.

Athal's turbo sounds good to me at the estimated numbers, cheap and easy is always good as well. :lol:

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Mon Aug 20, 2012 2:27 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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205 wheel at 12psi. That was on the big t04b somethingorother compressor. It was just getting efficient at that boost above 5000rpm and spooled pretty slowly. Going to the t3 felt way better due to the much faster spool of the smaller wheel. Probably didn't give up much at the top end either at that boost level- right in the efficiency sweet spot. It's on a 63 a/r exhaust with a ported wastegate so no issues with back pressure either.

As for your crankcase pressure- just loosen the oil cap. If it stays sucked down the system is working. If it hops around or gets blown off you either have too much pressure or the crankcase ventilation system is blocked.

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Mon Aug 20, 2012 9:46 pm 
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^^ Thanks Athal, that sounds like a decent setup, should be around 235-240 BHP if my math is right which is good enough for me. I'll send you a PM to discuss further.

Tried the oil cap trick tonight and it's rattling just a bit, stuck a nitrile glove on the dipstick tube and it slowly started to inflate as well so definitely have some excess pressure. I know when I got the car I snaked all of the vent tubing with a piece of rag on a coat hanger and they were clear. I also poured some degreaser down the oil separator during an oil change and it went straight through so it appeared that the crankcase ventilation was OK? I guess I'll order a new oil separator and recheck the tubing lines.

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Tue Aug 21, 2012 1:15 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Should have thought of the glove trick...at least you can get to the box on the block easily (relatively) and see if things are fine. I can't see it being rings but I don't know what B230FT's have for cranking PSI new. Anyone got the numbers?

I did mention that turbo's don't really have "oil seals" - but the shafts shouldn't WIGGLE a lot (like 100 thou) AFAIK. No other signs of oil - but the usage goes up if Jim's been thrashing it, ergo my assumption that the turbo is pooched. We could still leak it down, but we'd have to let it cool first or do it at your place.

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Tue Aug 21, 2012 1:29 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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The glove inflated? If so, that's a good indication that there's something wrong: the crankcase is directly vented to the compressor inlet pipe (slight vacuum) and to the intake manifold (moderate vacuum) so there shouldn't be any pressure in there at idle. The oil separator box (under the intake manifold) sometimes plug up with carbon - could be the problem right there. FCP sells the better, later style and they're cheap.

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Oil in a turbo is pressure-fed, gravity-drained. High pressure oil is fed to the journal bearings and flows around both sides of the bearing, cusioning and steadying the turbine shaft. (Note: without oil pressure, the shaft feels wobbly and loose, even when brand new, though it DOES get worse with age.) On the turbine shaft, no polymer seal would stand the heat (nor would it be frictionless) so an oil slinger and a piston ring seal are used in an attempt at keeping the combustion gasses in the turbine side and the oil in the cartridge. (The compressor side includes a thrust bearing and a labyrinth seal, sometimes piston rings, but also a slinger and very occasionally a positive seal for turbos that might operate with significant vacuum on the compressor inlet). Piston ring seals have a gap, and therefore are pretty poor at sealing, so something's gotta flow somewhere... Ideally this is exhaust into the oil, which produces a frothy chocolate mixture that returns to the crankcase through a massive drain tube. It's important that the drain is large and exits above the level of the oil in the pan, because it's so frothy it takes a massive column of the stuff to push its way down into even a small amount of liquid oil, or to overcome crankcase pressure.

As you’re cruising down the highway, your engine is producing a sustained 40-60 hp and the turbo is happily doing nothing. The compressor bypass valve is open so the compressor isn’t demanding work from the turbine, and therefore the turbine isn’t creating much backpressure. It doesn’t take much crankcase pressure to overcome the turbine pressure at this point and if you’re having trouble venting the crankcase at idle, I wonder what it’s like on the highway? You MIGHT try disconnecting the vacuum hose from the compressor bypass valve and plugging it, as a trial on one highway trip – this would put load on the turbo and would increase the turbine pressure, and it might alter your oil consumption. If it does, you have a pretty good idea that you’ve got a crankcase ventilation problem.

EBR is Exhaust (to) Boost (pressure) Ratio. A good guideline for a street turbo is 2:1, meaning 2 psi exhaust backpressure for every 1 psi boost pressure. Really high horsepower cars have less than 2:1, and full out racing cars can sometimes achieve less than 1:1 and that REALLY makes power. Typical OEMs are closer to 3:1 or even higher, so that they can sell the buyer on instant torque and no lag, while sacrificing that gratifying top end. Bigger compressors also require more torque from the turbine, which means more backpressure.

The 12B compressor is smaller than the 13C which is smaller than a 15G. The 12B is paired to a TD05 turbine, which may or may not be bigger than the TD04 that the 13C is connected to. I’m pretty sure the wheel of the TD05 is larger than that of the TD04, but the nozzle area of the 04 might compensate for that. I think Mitsubishi turbos require more hands-on experience than I have because there’s a whole lot more to them than just the numbers and letters. Anyway, the 13C is a better choice than the 12B, a TD05-15G would be better yet (aside from the 90+ boltup issue), but Athal’s Garrett is a slam dunk.


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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Tue Aug 21, 2012 1:48 pm 
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122_Canuck wrote:
Should have thought of the glove trick...at least you can get to the box on the block easily (relatively) and see if things are fine. I can't see it being rings but I don't know what B230FT's have for cranking PSI new. Anyone got the numbers?

I did mention that turbo's don't really have "oil seals" - but the shafts shouldn't WIGGLE a lot (like 100 thou) AFAIK. No other signs of oil - but the usage goes up if Jim's been thrashing it, ergo my assumption that the turbo is pooched. We could still leak it down, but we'd have to let it cool first or do it at your place.


When I pick up my goodies from Sol Thursday he is graciously (Thanks again Sol) giving me a used separator to soak clean and try out. I'll wait for feedback from others on what the new cranking PSI number is before speculating on blowby, but the UOA I attached earlier in the thread doesn't show significant fuel dilution or insolubles so... Maybe the system is still partially venting (it's definitely not plugged solid) and can't keep up at WOT blasts?

Craig, sorry if I misrepresented what you said about seals in a turbo. We're back to 2 cars again, so I could always park the Valdez at your place the day before and get a ride in the next day so we can work on a cool car. I'll get some crankcase ventilation PM done first and we can go from there.

ETA: 900th post, woohoo...

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Tue Aug 21, 2012 3:39 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Remember gauges and test conditions vary too. Darths two good cylinders, 3&4, come in right around 150-155psi. No piston slap noises so I'd guess your motor is probably fine.

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 Post subject: Re: Howdy! New guy requests advice re: pooched turbo...
PostPosted: Tue Aug 21, 2012 8:56 pm 
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^^^ Matt, thanks for all of that, this is starting to make sense. I am going to proceed with Stage 0 including finding out what's going on in the crankcase and then, if all is well, start on some mods.

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