Hey Guys,

Been a while since I've posted here on the forums. Been very busy the last few months. As many of you may remember I was one of the first to have the Greddy Turbo kit installed. I love it, but now after 6k miles I am having a very major issue. I am hoping that one of you may help shed some light on it.

Basically, this happens at random. The turbo will sound like it has stopped turning completely. When this happens it is impossible to get into positive boost. It comes and goes. I have sidelined my 8 for the time being until I can get this issue resolved. Also, I am getting oil into my exhaust system (white smoke). Oil is also leaking from the turbo. I checked my engine block and I am not leaking oil from the engine, just the turbo.

Any ideas on what this may be? Bad bearings perhaps? Any insight would be greatly appreciated.

-Jon

do a check to the cat coverter if it is clogged this overheat your turbo causing a premature bearing failure. Do you have a EGTgage installed? If youre run above 1350 deg. f. that's may your problem. The Greddy turbo kit tends to run at highter egt Temperatures, When i haved installed in my car i seen it up 1500 deg. F. An it melt the cat converter. :Wconfused

Yes i do have a EGT Gauge installed, It never goes above 700deg C. Doesn't even get close unless I am really really pushing hard.

I can say this with certainty. I moved to Georgia recently and drove my rx-8 down. 750 mile roadtrip. The issues didn't start until after the road trip was completed.

So you believe it's the bearings? If so that is good news. I can change the bearings out myself. Just have to find someone that can sell me a replacement set.

Tha's unit is from mitsubishi is easy ti find the repair kit . Turbo City In California. then have this one in stock for $125.00.

i'll recomend to you no use the car uppon you repair the unit to avoid complete unit failure. maybe you have only the seals damage. and this is cheap to repair.

You're in Athens? I wish I would have known that! I grew-up there and I just got back from spending 2 weeks there over the holidays! I would have been cool to say hello! Great town....great town.

Would a blown seal cause the lack of boost pressure? The lack of positive pressure only occurs sparatically.

I would also just like to say that I have already decided I will never again buy any Greddy turbo kit because they do not warrenty their parts. I don't buy from companies who don't stand behind their work.

sounds like the bearings are shot(oil keeps the shaft centered). New turbo is in order from what it sounds like. pull of the intake pipe and have a peak I bet it is eating the comp housing.... :(

Sounds exactly like bad bearings. If it was just some oil in the intake or exhaust, I'd say seals, but for the turbo to stop working is almost certainly bearings. While you've got it apart, you might as well get some work done to it. Get the vains clipped for a little more top end... ported and/or polished (the turbo, I mean).

I'm very seriously considering the Greddy turbo, so it's encouraging to me to see you have had good exhaust temps.

How have the underhood temps been? Do you keep track of them? Is driveability still good?

well i'm gonna have to go with popular opinion due to the fact that a local friend had a greddy twin turbo kit and both turbos died due to crappy seals and this was after bout 4-8 months i guess i'm just gonna stay NA or go with PFS kit damn you greddy

How have the underhood temps been? Do you keep track of them? Is driveability still good?


oh, the drivability is still great.. as long as I can get the turbo to go into boost... it's annoying not being able to drive right now. I need to take the turbo out and look at it to inspect it for damage.

Would bad seals cause the lack of boost pressure? It only happens every so often.

well i'm gonna have to go with popular opinion due to the fact that a local friend had a greddy twin turbo kit and both turbos died due to crappy seals and this was after bout 4-8 months i guess i'm just gonna stay NA or go with PFS kit damn you greddy


Do you think GReddy is making these turbos? They're not.

Unless the seals were heavily degraded, you should still be able to build boost. It also shouldn't be an occasional thing, if it were the seals. I'd put money on the bearings being toast. The bearings could be worn and still manage to line up sometimes, or most of the time as may be the case, but the turbo would stop spooling (or slow to a crawl) as soon as the bearings managed to fall out of alignment.


Honestly, I would think a bearing replacement wouldn't be much harder than replacing the seals. The bearings will probably need to be pressed in, which could be inconvenient, but it should be simple.

sounds a lot like the problem I had after only two months, i have heard that the oil drain is inferior but i am not sure on that, but to me, sounds like my blown seals and bearings. I actually had oil coming out of the cat pipe on mine! it would smoke when i started it until all the oil was out and then at idle, going down the road it did not. I was still getting boost though as I remember.

I upgraded the turbo in leu of rebuilding the greddy one.

Looks like I just joined the club of blown turbos. Died today on the dyno. Only 1000 miles on it.

Bummer to hear that. Do you know the exact sequence of events that led to its demise?
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Got a few more details. They did 5 or 6 pulls, made 287hp @8psi in 3rd gear. Then boost began rapidly falling off. Currently it will make something like 8psi at low rpms, but it rapidly falls off to <2psi. They pulled the intake pipe from the turbo and found lots of oil in the turbo housing.

sonofabitch....that's discouraging.

Can you tell us what kind of precautions they took as far as overheating went? fans, time between runs, etc?

I'm not sure, I wouldn't think any of that could cause the bearings in a turbo to go out though. My turbo has always been low on boost though ~4.5psi. So maybe it was defective to begin with.

So you weren't there when it happened? Damn, I don't think I'd let anyone touch it without me watching. Were they doing any tuning before the run that killed it? I'm picturing a glowing red hot turbo here. I would certainly think that overheating the turbo could cause the bearings to go out early.

It is a bummer,but you guys have been pushing hard.

I am in the process of installing a Greddy Turbo kit.Just for a fast touring car.

Just out of curiousity did anyone put a non-return valve in engine breather hose(even if you have a Greddy oil separator tank)?Is there an issue/effect of pressurising the crank case?

i know greddy doesn't make the turbos but they piss me off they know they have these problems yet still do not fix em, they give us crappy tuning with no apology or anything don;t waranty parts when they break. i just think its kinda bs, i'm not satisfied with greddy at all other than price of kit. but ohs well just seems a lil low class to me

maybe greddy kits keep blowing cause of over boosting...this stuff really just discouraged me of going with greddy...PTP better freaken come out with their turbo or ima be freaken pissed off

Ones Of the most causes for "Greddy Turbo" Turbocharger bearing failure is the abcence of BOV not including in the kit.

na, BOV on mine since the turbo was on there, i never spooled the turbo up without a bov and mine still went out. never up the boost either.

i have heard some opinions that the oil drain is a bad design, the spout coming out going to the oil pan, that it does not drain quick enough for a car with high rpms thus oil backs up, but oil is still coming into the turbo. there goes the seals.

I don't know the alternative oil drain though, does anyone else know other ways to drain a turbo, how is a stock turbo set up?
greddy turbos have also been very unrealiable in hondas also, same oil drain, or so i heard.

Well on TIIs the oil drain is not that disimilar,but it flows into the front cover.In my mind the more significant difference is water cooling of the turbo--according to Mazda data when the engine is shut down the metal of the turbo is about 302F lower with water cooling.So the risk with the Greddy is that if you do not manage the heat very carefully you fry the seals and bearings

maybe so, then an extra oil cooler might help, i dunno, if its oil temps then any oil cooled turbo would be prone to fail though, are that they unrealible on other vechicles?

Oil temperature inside the turbo when you shutdown the engine is the issue.If the metal of the turbo is too hot,the oil in contact with it will carbonise and the carbon grit and sludge will chew up the seals/bearings when the engine is restarted.
I think careful management prior to shutdown is the only way and the best oil you can buy(whatever that is).

sorry to hear about your turbo guys, now im having a second thought about installing the kit (GREDDY), i have gotten my turbo kit finally NOV 18 05 to be exact, and now this Thread mmmmm?????
i think im just gonna sit on it for a while :mdrmed: till somebody works the bugs out.
i like to boost ......someday,but i love driving my 8 TURBOED or NOT.
Daily Driven
PLEASE PLEASE PLEASE ROTARY GOD find a cure for our GREDDY KIT.

You've had it since NOV 18 05??? Wow, you've gots some patience, or just lazy. If it was me, it would have been in nov19,05.

I installed my greddy turbo 1 month after philodox and the turbo has almost 10k miles on it now. I've been running 10psi now for about a month with the interceptor X. Runs very good.
My turbo hasn't given me any problems at all (knock on wood). My probs were with cats breaking up, boost line leak, and the emanage w/ R-flash.

I was always EXTREMELY anal about shutting my car off after anything close to hard running. MY GF hated driving in my car until I got my turbo timer because she hated waiting for 5min while I let it cool down. Plus most other aftermarket turbos aren't water cooled and they don't break.

I was talking to turbonetics today and they said one of the leading causes of turbo failure is improper oil pressure. So perhaps the routing of the oil line, or the diameter of the oil line is incorrect and that is the cause of the failures.

I have a completely random idea, and really don't know if it would help or is possible. But maybe if you had the GReddy oil pan, with 2 spouts on the side, you could design some sort of oil return line shaped like a Y. That way it would allow more oil to flow out, and not get backed up.

I spoke about the problem with Rick from Rotary Performance, and he has an intersting opinion that makes sense. I'll try to relay what he was saying. When he installed PURNRG's turbo, and oil pressure gauge, he noticed that the pressure was significantly lower than what he had seen in previous generation turbocharged rotaries. He thought this may be a problem on his own turbocharged 8, so he has been running thicker weight oil, and this will make a small increase in the pressure. But apparently the problem has more to do with the engine design itself. When he rebuilt Saphonicca's engine, he noticed that our oil pump is only about the size of the 12A's pump, so its undersized. Although this may be fine while N/A, while turbocharged, its not going to allow the turbo to receive enough pressure, especially at lower rpms. This in turn will lead to the hot oil clogging up inside the turbo, and eating away at the bearings. He also said that when he was putting Saphonicca's car back together, he upgraded a part in the oil system. I can't remember what the name was, but it was by Racing Beat, and can be accessed by removing the oil pan. We also discussed how GReddy should have done more research into the characteristics of the engine before they released the kit, but more than likely, the problems people are starting to have aren't with their turbo kit at all, but with the engine itself. Maybe some gurus out there could do some research into this as soon as possible. If all these turbo's are starting to go bad in the winter, the summer is going to be very expensive for some of us.

Discuss!

[QUOTE=Moostafa29]I spoke about the problem with Rick from Rotary Performance, and he has an intersting opinion that makes sense. I'll try to relay what he was saying. When he installed PURNRG's turbo, and oil pressure gauge, he noticed that the pressure was significantly lower than what he had seen in previous generation turbocharged rotaries. He thought this may be a problem on his own turbocharged 8, so he has been running thicker weight oil, and this will make a small increase in the pressure. But apparently the problem has more to do with the engine design itself. When he rebuilt Saphonicca's engine, he noticed that our oil pump is only about the size of the 12A's pump, so its undersized. Although this may be fine while N/A, while turbocharged, its not going to allow the turbo to receive enough pressure, especially at lower rpms. This in turn will lead to the hot oil clogging up inside the turbo, and eating away at the bearings. He also said that when he was putting Saphonicca's car back together, he upgraded a part in the oil system. I can't remember what the name was, but it was by Racing Beat, and can be accessed by removing the oil pan. We also discussed how GReddy should have done more research into the characteristics of the engine before they released the kit, but more than likely, the problems people are starting to have aren't with their turbo kit at all, but with the engine itself. Maybe some gurus out there could do some research into this as soon as possible. If all these turbo's are starting to go bad in the winter, the summer is going to be very expensive for some of us.

Discuss![/QUO

MOOSTAFA , THAT'S REALLY IS NOT AN OIL PRESSURE SENSOR , IS A PRESSURE SWITCH WITH A PROGRAMATED GAGE SCALE. WHEN I REMOVE SENSOR FROM THE ENGINE I NOTICE THAT'S ONLY A PRESSURE SWITCH INSTEAD OF PRESSURE SENSOR. :naughty:

You are talking about something completely different. I'm refering to an aftermarket gauge, not the switch that you remove and hook the supply line up to.

According to the Manual,the reference oil pressure in Renesis is 51psig at 3000rpm,with oil temperature of 100C.This is about the same as the spec for a TII.I checked the oil pump size for the TII,and it is about 50% greater than a 2nd gen NA.

Oops,I intended to ask what kind of oil pressure those with proper oil gauges are seeing?

talk amongst your selves guys, we might just find out what the deal is with these turbos!

Hmm. I put a restrictor in my oil line when I installed it - I was worried about the oil pressure being to high coming straight off of the sender.
I've done this on all of my turbo cars. Turbos need very little oil. Too much pressure with blow the seals and too much flow will do strange things to the bearings.

The oil source tube that comes with the Greddy kit is huge compared to mine as well - it is nearly twice the inside diameter (outside too) and a good 6 inches shorter.

I am about to install a Greddy turbo/manifold on Monday (just 'cause I can - how do you like them appleshttp://www.mazdamaniac.com/portal/smiles/nana2.gif ) while I take my turbo/manifold off for investigation (I have a small exhaust leak on the engine side of the tube between the center and rear ports and I am building a better version of the manifold, so I need it off the car for a while but I can't stand to be without turbo for any length of time:Freak_ani (http://misc.php?do=getsmilies&wysiwyg=1&forumid=93#)), so I will be able to give you all a little report on the kinds of minimum pressures the turbo can take.

BTW - the draining issue isnt the quality of the drain itself - it is the position of the turbo.
Fluid holds its own level and the bottom of the turbo is already really close to the top of the oil level in the sump. This means the drain rate isn't going to be very fast.
The trick is to only get the oil moving through the turbo via gravity and no more.

I've seen cars with a very low mounted turbo that had their own small pump to help move the oil through the turbo. I believe this was on a Corvette and the turbo/s were actually mounted below the engine. It had a small electric oil pump. perhaps someone could try this. If MazdaManiac really believes that oil getting backed up in the turbo could be a problem.

Corky Bell mentions that kind of thing in his book.
I don't know if backed up oil or incorrect pressure is the culprit, though I would bet that it is high pressure that is doing it in.

Isn't the factory drain location that the Greddy turbo return line uses below the oil level of the pan? Otherwise how would the oil drain during an oil change? It seems to me that this isn't a good idea for drainage, unless enough oil is circulating through the engine when running to pull the level down sufficiently.

the turbo drain is higher than the oil pan drain.

You mean with the Greddy oil pan? Alot of us are still using the stock pan.

well mm was talking about the oil feed line so i thought i say yeah, my new oil feed line i bought was much smaller than the greddy one and a little longer.

What exactly is an oil restrictor, where do we get them, and how do we know if the turbo is getting enough oil?

mm, ya may have found the problem, my seals were gone and of course bearing, this may be the culprit!

I made my own restrictor, but you can get on from any turbo supply place.
It is just a little brass insert that goes inside the feed fitting on top of the turbo with a smaller orifice than the hose. I think it is .035", but I'm not sure at the moment.

of course ya made your own, ya da man! :)

if i get the specs on my oil feed and pm them to you would you mind looking at them to make sure the restrictor will not cut too much oil off? this is kinda techy for me, i am learning as i go, the only way to learn, but sometimes expensive way:)

i'm gonna agree with MM on this issue i think that the pressure of the oil is gonna be the culprit i was talking to a friend about it last night and thats the only thing that we could think of that could cause this problem that or the fact that the turbos are just junk. now about drainage though the pressure would be low (with restrictor) it should still be enough to flow through turbo unless your oil pan somehow became pressurized but thats just my $.02

Our turbo is a common turbo that many people have been using for a long time without problem. Granted Greddy does modify it, but I believe the bearings and seals are still standard Mitsubishi style. At the very least the 350z's twin turbo setup uses a similar turbo, TD05-18g, and I was checking the 350z forums the other day and they don't seem to be having a problem. So, while they're not the greatest turbo, I don't think they're junk either. I think the oil pressure is a likely culprit. Maybe if we put a pressure gauge on the line, and measure the pressure, we can confirm with Greddy if that is what they expected when they designed the kit.

Unless you have a non-return valve in the engine breather hose ,your engine,oil pan and oil separator will be pressurised when you boost.

According to the Manual,the reference oil pressure in Renesis is 51psig at 3000rpm,with oil temperature of 100C.Can you quote what the reference pressure should be at idle, around 750 rpm? 'Cause my pressure gauge says it's around 8-10 psi at that point. Even if it is in spec don't you think that's really low?
________
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I think that would be fine. I've always heard generally you want 10psi for every 1k rpms.

Can you quote what the reference pressure should be at idle, around 750 rpm? 'Cause my pressure gauge says it's around 8-10 psi at that point. Even if it is in spec don't you think that's really low?

Yes,it is in the 2004Service Highlights(part no 9999-95-102F-04)and on p01-00-3.

Also please ignore the above post on engine breather checkvalve,I am doing mine different to the Greddy set up and I forgot.

Can you quote what the reference pressure should be at idle, around 750 rpm? 'Cause my pressure gauge says it's around 8-10 psi at that point. Even if it is in spec don't you think that's really low?

Sorry,I really should read what you wrote!I have not found a reference oil pressure for idle speed.From my TII days,10 psig at idle and hot was typical.

I have not found a reference oil pressure for idle speed.From my TII days,10 psig at idle and hot was typical.Are you sure about that? My sources indicate RX-7s were at 30psi at idle and anything below that was cause for concern.

To expand upon what Moostafa wrote, Rick noticed the RX-8's oil pressure regulator is (in his opinion) unusually small. It may be my 10psi @ idle is lower than spec due to diverting some of the oil pressure to the turbo. This is speculation on his part but sounds reasonable.

He installed a Racing Beat oil pressure regulator (pn 11810, $90) originally intended for a '71-'92 RX-7 in Sapphonica's car during his rebuild. It should add roughly 15 psi across the board. I note MazdaManiac's concern about too much oil pressure but think what Rick said about low psi @ idle makes sense and might be a contributing factor to the turbo bearings wearing out so soon. I have one on order and plan to install it shortly.
________
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actually quite a few 350z's are having problems with the turbos they actually released a tsb sorta thing about it i know someone whos turbos ate themselves after less than 6 mo

Are you sure about that? My sources indicate RX-7s were at 30psi at idle and anything below that was cause for concern.

To expand upon what Moostafa wrote, Rick noticed the RX-8's oil pressure regulator is (in his opinion) unusually small. It may be my 10psi @ idle is lower than spec due to diverting some of the oil pressure to the turbo. This is speculation on his part but sounds reasonable.

He installed a Racing Beat oil pressure regulator (pn 11810, $90) originally intended for a '71-'92 RX-7 in Sapphonica's car during his rebuild. It should add roughly 15 psi across the board. I note MazdaManiac's concern about too much oil pressure but think what Rick said about low psi @ idle makes sense and might be a contributing factor to the turbo bearings wearing out so soon. I have one on order and plan to install it shortly.

Again the standard way to evaluate oil pressure is at 3000 rpm,and the spec for the 2nd gen is 64-78 psi at 3000rpm.I had 6 RX-7s over a14year period and 5 had idle oil pressures in the 10-15 psi.

Is it a particular turbo kit that the 350z's are having problem with?

I called Greddy to see if I could get the turbo covered under warrenty. They will rebuild it if the seals are bad, but will not do anything with it if the bearings are shot. They claim there's no way the bearings could have been defective, so it must have been a faulty install or abuse. Really, I think its a matter of, its cheap for them to replace the seals, its just new gaskets, but it would be expensive for them to fix blown bearings/damaged housing. So they're going to concede on the easy one. I think thats really screwed up considering the warranty statement they have posted on their website. It specifically states they do warranty their parts and do not rebuild parts, they replace them to ensure reliability. I don't understand how they can post a statement like that and then totally not honor it.

The RX-8 turbo kit has a disclaimer at the end that indicated that this kit is completely NOT under warranty.

Checking oil pressure before the turbo won't tell you anything if you have a restrictor. I looked at mine last night - it is 1/16". I had taken it apart because I needed to look the setup over.
Right before I put it in the garage, I lost boost. Turns out it was a piece of metal that broke loose from the internal deflector inside the manifold and lodged into the turbine! I had driven it like that for 5 or 6 miles when the boost stopped.
Absolutely no damage. Garrett makes one tough turbo...

I've been calling around to a few places looking for some options and one of the places I called is Turbo Trader, a dealer for Bullseyeperformance, the company that performs the Greddy turbo upgrade. They have rebuilt a few blown Greddy turbos and told me the cause of the failures was due to compressor surge destroying the bearings. They said the 18g just isn't a properly sized turbo for our engine. It isn't happening to everyone because it just depends on your driving habits whether you hit that surge line or not. They replace the 18g wheel with a Garret 50trim and claim it is much better sized to our flow requirements. I have no idea if this is true of course, just one shops opinion. Surge damage could also be from running around without a BOV.

I have plumbed my Greddy system with a recycle line in a similar fashion to the Mazda TII system(in fact I am using the TII air by-pass valve).Hope fully I will avoid any surge issue.

yea i remember dan at bullseye telling me that the gredy turbo was all wrong and would surge.

I really really dislike greddy!

Well, I installed my Greddy turbo and manifold yesterday and drove it a bit today.

It is trying to produce boost all the time, even under light throttle. I can see why it is sitting at its surge limit all the time.
However, there is also something wrong with the way Greddy has you set it up.
The boost signal for the wastegate is coming off of the intake manifold. That is the wrong place.
There should be a return signal at the outlet of the turbo itself that feeds the wastegate. That way, it isn't trying to build full boost all the time.

That said, I can't wait until I get all moved in and get my welding rig here in AZ from MD so I can fix my manifold and go back to my turbo.

Wrong Thread.

bullseyepower is making me a restrictor for the oil feed line, its all making sense now, i just noticed some oil in the intake pipe, which makes sense that there is blow by in the turbo from too much pressure, probably is the reason the greddy ones don't hold up coupled with the surge.

The oil in the intake pipe could be blow by from the crankcase ventillation and not from high oil pressure pushing oil passed the seals though. Do you have an oil catch can?

MM, do you think tapping a fitting at the outlet of the turbo for the wastegate signal could help the Greddy turbo stay out of surge?

Do you think the turbo could be corrected by just replacing the compressor side as Bullseye does? Or do you think it would need some work done to the turbine side as well?

It really makes no difference were you tap the reference line for the wastegate. The only difference that you would see is if you are just useing the spring in the wastegate to control boost you will see two different boost levels. The one off the intake would most likely be a higher boost pressure than the one that is referenced off the compressor cover because when you reference off the compressor cover it does not compansate for the pressure drop across the intercooler (if you have one).

IMHO Greddy just dropped the ball on the turbo match for the Renesis motor.

I would think it could make a difference because the boost level should be proportional to throttle position. If you tap the signal after the TB then there is no relation to throttle opening, it just means the turbo is less efficient at part throttle because it has to squeeze all that air through a smaller opening, but will always make full boost. If you tap the signal prior to the TB then the boost level in the manifold would be better controllerd by throttle position.

You can not make any boost unless you have the throttle open. If you do not open the throttle you will not make enough exhaust energy to spin the turbo.

I can make full boost at <1/2 throttle. Close to full boost at <1/3 throttle.

Considering my throttle plate is going to be acting as a huge restriction at <1/3 throttle, I would think the turbo is spinning the begeses out of its bearings trying to make full boost in the intake manifold. I bet the pressure at the turbo outlet is much higher than the 6psi I read in the manifold, and with very little actual flow -> Can you say Surge. :cussing:

I bet the pressure out the turbo outlet is much higher than the 6psi I read at the manifold,


I know that there is more pressure that compressor then in the manifold.

You are correct when it comes to not enough flow. When the motor cannot injest enough air it gets backed up in the compressor cover and causes surge. There are some turbos that have a wider range of air that they can flow.

Look at the compressor map of the 50 trim compressor wheel:

http://www.theturbotrader.com/images/50trim.gif

At 6psi or a pressure differential of 1.4 it can flow any where from 8 lbs/min up to 28lbs/min. Which makes it very forgiving on the amount of air flow that it can move.

I think I've missed your point. Are you saying that the Greddy turbo should be fine based on the 50trim wheel being so flexible? If so, I don't think thats a very good comparison. Not all compressors are that flexible, and the 18g is completely different from a 50trim. It would be nice if we had a compressor map for our turbo though.

Sorry for not being too clear. I am saying the 18G (which I can not find a compressor map for) must not be as forgiving. That is why it is getting into surge so easily.

MM, do you think tapping a fitting at the outlet of the turbo for the wastegate signal could help the Greddy turbo stay out of surge?Possibly. I will try it as soon as I can. It is an easy mod, but It requires that you remove the outlet pipe to avoid having shavings go into the turbo when you drill and tap the fitting.

Do you think the turbo could be corrected by just replacing the compressor side as Bullseye does? Or do you think it would need some work done to the turbine side as well?Both sides are too small. As soon as I can locate a compressor map for the TD06-18G, I'll see what the possibilities are.


You can not make any boost unless you have the throttle open. If you do not open the throttle you will not make enough exhaust energy to spin the turbo.
With a properly sized turbo, this is mostly true. However, mine will try to hit the full boost target a a touch of the throttle. It is, IMNSHO, undrivable.

For anyone else worried about this and considering upgrading their turbo, here is an email I got from a Bullseye dealer describing their analysis of failed Greddy turbos.

>>
Ryan

I talked to you yesterday. Dave over at Bullseye Power forwarded me your email. I worked at Bullseye, but now I have my own. I am over at The Turbo Trader.

I am guessing that you have been talking to Chris about his Greddy upgrade. From what we saw on his turbo the front side of the thrust bearing was all beat up, which shows that the compressor wheel was surging very badly and they was the main reason that the turbo failed.

The turbo did show other signs that there was an oil problem that could have shortened the life of the turbo. It looked like oil had been backing up in the lower portion of the center section. It did not seem to be backed up enough to blow out the seals, but it was enough that the oil was starting to choke and block off some of the passages in the center section. From what I have seen of the Greddy turbo kit the oil drain has very little to be desired. I can't imagine that by draining the oil back into the oil pan were you drain the oil from to change it can not be the best idea.

These are just ideas. We do not have a car that we can really do some major testing on.

I facts that we know is that the compressor wheel was surging and destroyed the thrust bearing. The other thing is that the oil drain is barely adequate.

The turbo upgrade solves the main issue which is the surge by using a 50 trim compressor wheel that can handle the lower amounts of air flow, but also be able to hold boost up till redline. As far as how much boost it can hold is just a guess right now. We are almost 100% it will hold well over 15psi to red line. This turbo can handle up to 480 hp at 25+psi. It should be able to handle almost any horse power range that most people would want to through at it. If some one needs more power and has the supporting mods we can do other compressor wheels if needed.

Let me know if you have any questions.

Thanks,


<<

Just a reference point: my GReddy turbo has about 16,000 miles on it right now. The first 12k or so it was making ~280whp. Since I got it, I haven't run the boost as high as the first owner did.

It depends on how you drive it as to whether you drive the turbo into surge. If you are often at higher rpms with more throttle, it will probably not be driven into surge. I spent alot of my time in boost, but at low throttle positions. Especially when I had the emanage because to much throttle caused it to run shitty.

The less throttle or lower rpms result in less flow, but the boost is always maxed at the wastegate setting. If the turbine was bigger it probably wouldn't be as much of a problem because it wouldn't have enough energy to spin up the turbo unless you were full throttle, or close to it. But the combo of the small turbine and the location of the wastegate line results in the possibility of high pressure at the compressor outlet and very little flow.

If all else fails ,look at the way Mazda did it originally!Indeed the port for the wastegate is right on the discharge.But the really damaging surge condition occurs when you snap the throttle shut and air is forced back into the discharge side of the compressor.Your blow-off valve or recycle valve needs to act fast and is perhaps more important in preventing a surge condition than the wastegate.
My recycle line opens on vacuum from the port where Greddy take the wastegate signal.

I'm going to have to re-think my position on the Greddy turbo being too small.
I am looking at the compressor map for a TD05-16 right now and it is, mathematically, the perfect turbo for the RX-8. I would imagine (though it is highly possible that this is not so) that the TD06 version would actually flow even more. The TD04-18 is equally good.
Has anyone found a map for the TD06-18G yet?

Here are the maps for these turbos with the performance line for the Renesis drawn in. I based this on 9 PSI and a max airflow of 370 CFM.

so the greddy turbo is the perfect one for the rx8? is that what u saying?

so the greddy turbo is the perfect one for the rx8? is that what u saying?You need to re-read my post.

please explain jeff for those of us who arent used to looking at compressor maps

Isn't it more likely to be be the turbine side being too small, or having too small an A/R causing the turbo to spool so easily?

Here's the best I could do A TD05H-18G :D: Should be very close

please explain jeff for those of us who arent used to looking at compressor mapsWell, the compressor map has two axis:
The vertical axis is the pressure ratio which is the amount of boost expressed as a multiple of atmospheric. 1.0 is atmosphere (~14 PSI or zero boost). A pressure ratio of 1.4, therefore, is 19.6 PSI or 5.6 psi of boost. I use 9 PSI of boost as my reference when sizing a turbo because that is, IMHO, optimal for this motor since it runs out of fuel at that point. That is a pressure ratio of about 1.6.
When you compute your pressure ratio, you also need to take into account the losses through the intercooler. I usually use 1.5 PSI. This would be the difference between what the turbo puts out and what you actually see at the manifold. This means you need a pressure ratio of 1.75 or so to actually see 9 PSI in the manifold.

The horizontal axis is flow. That is the amount of air going into the engine. This is a function of the relationship amongst displacement, RPM, outlet or intercooled temperature (which affects charge density and is a function of compressor efficiency which can be as high as 75% to 85% for a turbo and one of the reasons it is better than a supercharger at 65% or worse, but I digress) and the estimated volumetric efficiency of the engine which ranges between 70% and 100%. Generally, you assume about an 85% average volumetric efficiency (Ve). The N/A flow rate of the Renesis is about 275 CFM at 9200 RPM. At a pressure ratio of 1.6, the Renesis will consume about 400 CFM of air assuming the IC will cool the air down to 130°F or so from its peak of 210°F out of the turbo.
The flow rate is often expressed as lbs of air (a mass number) instead of a flow number like CFM because this is better reflective of the effects of temperature. 400 CFM at 200°F is a lot less air than 400 CFM at 110°F.

Now, the concentric circles on the compressor map show the ranges of efficiency for the turbo at different flow rates and pressure ratios. Using the map that Dannobre provided (which may or may not be good since it is deduced from the existing map of another turbo), you can see that the turbo operates at its highest efficiency (77%) at the pressure ratios and flow rates in the center circle. This turbo is really happy at 14 PSI of boost and 350 CFM of flow. At WOT and 400 CFM, you should be able to put 16 PSI to the Renesis manifold easily! This all falls in the inner efficiency circle. As you move out to the concentric circles, the turbo gets less and less efficient, but still produces boost. This means it is producing more heat to make that boost. You can see, this works against you in several ways.
The turbo doesn't like trying to flow more air at the same boost or more pressure at the same flow. But it also doesn't like making less pressure at the same flow or less flow at the same pressure. If you go off the last line to the right, you are no longer able to force any more air into the manifold without superheating it. If you go off the last line to the left - that is surge. Both are reversion - where air is trying to go back into the turbo. The low end - surge - is the dangerous part because it can actually stop the compressor from spinning quite suddenly which damages the bearings.
This is when the turbo is trying to produce boost with very little flow. Though our little turbo is quite happy making 9 PSI at 400 CFM, it will not be so happy at 9 PSI with only 100 CFM going by. This means your turbo will be surging if you try to make it produce 9 PSI at 2300 RPM.

Now, to use this information, all you do is select a bunch of arbitrary RPM points and express them as a linear percentage of full flow and plot those points on the map. If they all fall all in the better parts of the map, you have the right turbo. If not, you have the wrong one.
Here is an example of a bad one, the T66:

http://www.rx8club.com/attachment.php?attachmentid=67702&stc=1

Here is an iffy one, the KKK K26 (IIRC, this is the turbo on the VW and Audi 1.8T)

http://www.rx8club.com/attachment.php?attachmentid=67701&stc=1

The problem here is less evident. It will work, but it is not really ever in its most efficient point.
Now, we look at the TD05H-18G.

http://www.rx8club.com/attachment.php?attachmentid=67703&stc=1

As you can see, it should comfortably produce the desired boost across the RPM range with no problem.
What I'm not sure of here is what the differences are between the TD05 and the TD06. I suspect it has something to do with the turbine efficiency which is a whole other discussion.

... so. Where does this leave us in terms of the issues at hand?

... so. Where does this leave us in terms of the issues at hand?Well, the first thing is to control the out-of-control spooling.
I really think that referencing the wastegate to the compressor outlet will do this.
The additional control of a boost controller will further this effect by allowing the signal to go unimpeded when there is vacuum in the manifold.
Having the turbo partially free-wheeling when the manifold is not in boost will relax the throttle response a little and eliminate the surging. It will also allow those with atmospheric-venting BOVs to release the tension on the setting screw a bit since it will not be under so much stress to blow open all the time. This will further relive the surge without adding to the stalling issues.

The other day when I was trying out one of MadDog's new turbo maps, I ran into a problem where, under light but constant throttle, the mix went to an AFR of 10:1 or richer. After thinking about that on the plane ride home, I realized that it was the crazy boost that was probably present in the intake tract opening the BOV and the MAF was reading all kinds of air that wasn't actually going into the motor.

Where this doesn't leave us, however, is explaining why some (or most) people are loosing boost at higher RPMs.

I won't be back to my RX-8 for a few weeks, so I can't investigate any of this for a while. Hopefully, someone will take up the gauntlet.

The other day when I was trying out one of MadDog's new turbo maps, I ran into a problem where, under light but constant throttle, the mix went to an AFR of 10:1 or richer. After thinking about that on the plane ride home, I realized that it was the crazy boost that was probably present in the intake tract opening the BOV and the MAF was reading all kinds of air that wasn't actually going into the motor.

Hmm... Interesting. I have an HKS SSQV which functions on alterations in pressure. I guess that might explain why I don't have the problem you saw.

MD

Hmm... Interesting. I have an HKS SSQV which functions on alterations in pressure. I guess that might explain why I don't have the problem you saw.

MDI also have the HKS super-sequential.
It work by a comparison of the vacuum signal and the available diaphragm pressure. If there is more pressure behind the diaphragm than in front of it AND there is a vacuum signal, it will open. All BOVs will open under those conditions.

The other day when I was trying out one of MadDog's new turbo maps, I ran into a problem where, under light but constant throttle, the mix went to an AFR of 10:1 or richer. After thinking about that on the plane ride home, I realized that it was the crazy boost that was probably present in the intake tract opening the BOV and the MAF was reading all kinds of air that wasn't actually going into the motor.


Yes yes.... i have this problem... it happens at -0.2 up to +0.2bar.....

It helps when i lower the amount of fuel at +0.2 bar.. but not a lot.... I can't do anything about - boost though

PS. I use the SQV too

Yes yes.... i have this problem... it happens at -0.2 up to +0.2bar.....
OK. Well, try what I suggested - install a vacuum fitting on the outlet pipe of the turbo and plumb your wastegate signal there and see what happens.
Your set boost will appear lower, but you can increase it with your boost controller.

This is a little off topic, but MM...that is the best avatar I've ever seen.

yes unfortunately i had to get rid of it- against forum rules. try another Jeff.

Damn....

Since when is Willie Nelson against the rules?

jef thanks for the great compressor map explanation too. really appreciate it.

but the avatar again had to go

Now no one has avatars? What was wrong with the last one?

Well I pulled down my turbo Saturday. There was a good amount of oil in the housing and the piping, but other than that the turbo looked to be in good condition. It spins freely with no scraping. There is no in and out play, there is a very small amount of up and down, probably <1/8in. Is there any up and down play permitted or is it toast?

Also I found what looks like a coolant leak from around the intake manifold. Not to happy about that. Can anyone tell me if this will turn into anything more serious than the occassional need to add more coolant? Here's a few pics of it.

Up and down is OK because of floating bearing.

I was under the impression that only the slightest bit of "up-down" play is acceptable.

I'd say, 1/8th of an inch means the turbo is toast. That seems like way too much play, but as long as the turbo is spooling... it's got to be fine.

I sent my turbo out to Scott at Mazsport to rebuild. He gave me the diagnosis on it yesteday. The seals and bearings were shot, and the shaft was blue. He thinks when I was using the emanage I had some lean spikes causing very high egt's which killed the turbo. Hopefully now with the Interceptor that won't happen.

Check your cat coverter maybe is was melted too.

Actually, no it didn't melt. I would have expected the same thing. Maybe the turbo absorbed most of the excess heat.

I sent my turbo out to Scott at Mazsport to rebuild. He gave me the diagnosis on it yesteday. The seals and bearings were shot, and the shaft was blue. He thinks when I was using the emanage I had some lean spikes causing very high egt's which killed the turbo. Hopefully now with the Interceptor that won't happen.Nope. Shaft is blue because the turbo stopped spinning when the bearings died and it cooked with no flow.
A spinning turbo can take 2400°F without flinching.
You had oil pressure/flow problems in the turbo itself and/or surge.

I asked Scott if it was looked like oil pressure problems. He said it was unlikely since there was no physical damage to the shaft at the bearings locations. Do you think that is a good indication that oil pressure was okay? Would surge damage have been easily visible in any way?

Do you have any recommendations for anything I should do before reinstalling the rebuilt turbo?

I asked Scott if it was looked like oil pressure problems. He said it was unlikely since there was no physical damage to the shaft at the bearings locations. Do you think that is a good indication that oil pressure was okay? Would surge damage have been easily visible in any way?

Do you have any recommendations for anything I should do before reinstalling the rebuilt turbo?Bearings are soft. Shafts are hard (stop giggling).
If there was damage to the shaft, something really catastrophic would have to have happened.

If the oil pressure is too high, the damage is caused by the shaft oscillating inside the bearings and battering them apart and alternately coming in contact during that vibration as the oil seeks a path around the shaft.
Surge does the same thing, but for shorter durations at a higher inertial value.

I talked to reputable shop today. They recommended to test the oil supply by cranking the engine for 10 seconds without the turbo installed and measuring the oil flow from the turbo supply line. It should be about 1/2 cup. Not the most accurate way to determine the condition of the oil supply system, but should give me an idea of whats going on. I think I'll make a special trip to try this out this weekend. Does anyone know of a better way to ensure the turbos getting proper oil supply?

Well, I know what the problem is with my turbo now. There's about 1/4 inch play in the shaft. So I think the turbo is completely blown. Sending it out to a shop to have a professional look at it today. Will keep you all posted on what happens. Hopefuly bearings is all it needs and I didn't damage the housing... time will tell.

FYI when the turbine shaft is blue that comes from a lack of oil. It can happen because of a lack of oil while running or else if the car stalls and the turbo is still spinning at high speeds.

For all those people that are sending off their turbos have the rebuilder look at the thrust bearing if the front side of the bearing is beat up then that is a guarenteed sign that your turbo had been surging.

When checking your turbos they will have some up and down movement. If it has in and out play then it is TOAST!!

Well, I went to do some more investigation today. I refilled the car with oil, pulled the fuel pump fuse and cranked it to see how much oil came out of the turbo oil supply line. After 10 seconds of cranking nothing. Not a drop. There should be sufficient oil pressure during cranking to flow oil through that line, right?

If the turbo had no oil, obviously that explains why it died. But I don't understand how there was tons of oil inside the turbo and intake piping. Where did that oil come from then?

You need to run the car at regular RPMs for a few minutes before this measuring method is viable.
There needs to be oil pressure established throughout the entire lubricating system at standard running temperatures. If the car had been sitting for any length of time, all of the oil was in the pan and it would take several hundred RPMs before any pressure was established - especially if it sat completely drained. This is why they recommend pulling the EGI fuse and cranking whenever the oil has been completely drained to avoid causing serious wear during that first start-up.
However, you probably should have seen at least some oil after 10 full seconds of cranking.

It helps to pull a plug from each rotor so you geta faster crank speed.

I'm back up and running. Finished reinstalling the turbo last night. Runs great from what I can tell. Haven't hammered it yet as its not fully tuned yet. I had a tuning appointment scheduled for today that I made 2 weeks ago. I took off work and was on my way there. Decided to call and let them know when I'd be there. When I called, they had apparently completely forgotten about this appointment and had to cancel. Very annoying since I had already taken off of work. I might just try to tune it myself, still trying to work up the balls though.

Intake air temps definitely dropped considerably with the new CAI. I used to see 95+ degrees intake air temps at stops, then it would fall to about 65 degrees while driving. Now I see a constant 30-32 degrees. Although, this is slightly skewed because it is colder now than before my turbo blew. I also had all the exhaust parts ceramic coated, so that may be helping as well.