Why oh why is every turbo dead after about 600km....
06-06-2007, 08:39 PM
#11
3.0 BAR
Join Date: Jan 2003
Posts: 4,438
Re: Why oh why is every turbo dead after about 600km....
could be tune but you also could need more oil volume to the turbo to keep it cool and the bearings lubed. IDK why you guys are afraid of using bovs... Using a bov keeps the turbo spinning because without one when you slam the throttle shut even for a second, it makes a pressure wave that makes its way back to the turbo and slows it down somtimes violently (compressor surge) plus it tends to keep your charge air temps down
06-06-2007, 09:44 PM
#12
1.0 BAR
Join Date: Sep 2006
Posts: 326
Re: Why oh why is every turbo dead after about 600km....
Originally Posted by NNBD
With ALS we just retard the ignition up to -70 degrees, and add a bunch of fuel, so we get an mixture burn in our exaust manifold. This way we force the turbo to keep spooling. This is just for a very short period.
You're mentioning exhaust gas temps of 900C - that's high.. Way high. Timing at -70, rich, you'll be running an exploding mixture right past your exhaust valves - no wonder you've got temps that are that high.
I believe dino oil starts to coke around 1200F or so. Synthetic higher, but I'm thinking at those EGTs you're hot enough to easily coke oil on that rear bearing. I'd have to check the coke point of synthetic, but those EGTs are really up there.
Air inlet restrictor is interesting also.. That and a pressure ratio above 2, you've got to be really spinning the crap out of those turbos.
06-06-2007, 10:47 PM
#13
0.0 BAR
Join Date: Feb 2003
Posts: 0
Re: Why oh why is every turbo dead after about 600km....
You have some wierd oil feed issue, oil drain issue, or super hot EGT issue.
You are actually killing off "throttle response" by stalling the turbo by doing this. You are killing the turbo's bearings, to boot. Connecting a dumpvalve/blow off valve/recirculating valve/bypass valve/wtf ever you want to call it valve back into the system will cost you big fat -0- loss in "throttle response."
It's kind of funny to hear you talking about "throttle response"
I hear that term from all the sissy small displacement engine heavy car naturally aspirated ITB kids, they use the phrase like it means something? I dunno, every time I mash the gas pedal on one of those cars I don't feel any response.
Originally Posted by NNBD
It didn't have a dumpvalve since we don't like them 
we like to keep as much air in the chargepipes as possible so we have a good throttle response.
we like to keep as much air in the chargepipes as possible so we have a good throttle response.It's kind of funny to hear you talking about "throttle response"
I hear that term from all the sissy small displacement engine heavy car naturally aspirated ITB kids, they use the phrase like it means something? I dunno, every time I mash the gas pedal on one of those cars I don't feel any response.
06-07-2007, 02:44 AM
#14
0.5 BAR
Thread Starter
Join Date: Sep 2004
Posts: 175
Re: Why oh why is every turbo dead after about 600km....
well, let me try to explain the reason for not using a bov....
With a bov, the air is ventilated to the atmosphere, the turbo likes it since it can spool "unloaded". thats great on street cars indeed.
On a rally car we want as much air in the chargepipes with as much pressure as possible. When hitting the throttle its like you let of a normal compressor...it realy discharges into the intake..it works like a buffer.
Also, we never shut the throttle 100%. its always a bit open, like 20% ...depends on the amount of ALS we want to use.
When not using a bov, pushing air into the charge pipes..the turbo will slow down, its getting pressure etc etc, it doesn't like it, we don't like it.....we know. BUT therefore we have ALS. its just like you use your exhaust manifold as combustion chamber. it forces the turbo to keep spooling. No...the turbo REALLY doesn't like this...but we do
Its giving us more instant boost than any other system. Normally, a turbo lasts for like 2500-3000km, which is acceptable. Means that we should kill 2-3 turbo's a season..... Remember, it does not have to hold together like a street car...but it has to be acceptable.
Also, without ALS we get like 600-700 degrees EGT, don't know by heart, With ALS it can go up to a max of 900 which is our limit. Its only that high, a fraction of the time when using ALS.
With a bov, the air is ventilated to the atmosphere, the turbo likes it since it can spool "unloaded". thats great on street cars indeed.
On a rally car we want as much air in the chargepipes with as much pressure as possible. When hitting the throttle its like you let of a normal compressor...it realy discharges into the intake..it works like a buffer.
Also, we never shut the throttle 100%. its always a bit open, like 20% ...depends on the amount of ALS we want to use.
When not using a bov, pushing air into the charge pipes..the turbo will slow down, its getting pressure etc etc, it doesn't like it, we don't like it.....we know. BUT therefore we have ALS. its just like you use your exhaust manifold as combustion chamber. it forces the turbo to keep spooling. No...the turbo REALLY doesn't like this...but we do
Its giving us more instant boost than any other system. Normally, a turbo lasts for like 2500-3000km, which is acceptable. Means that we should kill 2-3 turbo's a season..... Remember, it does not have to hold together like a street car...but it has to be acceptable.Also, without ALS we get like 600-700 degrees EGT, don't know by heart, With ALS it can go up to a max of 900 which is our limit. Its only that high, a fraction of the time when using ALS.
06-07-2007, 03:00 AM
#15
0.5 BAR
Thread Starter
Join Date: Sep 2004
Posts: 175
Re: Why oh why is every turbo dead after about 600km....
oh btw...here is a little movie of the last rally. The yellow/purple EVO4 is one of us, it runs great ! at 3.09 it makes a mistake, but afther that you can really hear the ALS...first when he goes off the gas you can hear the air being pushed back into the air filter, then when filmed from behind you can hear the exhaust cause of the ALS.
http://www.youtube.com/watch?v=AwjcnwmbhYY
PS: the very first car WAS our evo 5...it wrecked....got pics.
http://www.youtube.com/watch?v=AwjcnwmbhYY
PS: the very first car WAS our evo 5...it wrecked....got pics.
06-07-2007, 03:29 AM
#16
0.5 BAR
Thread Starter
Join Date: Sep 2004
Posts: 175
Re: Why oh why is every turbo dead after about 600km....
for those that like some pic's, here are some pics of the last rally and 2 from our private testday.
the cars (not al of them (testday))
Testday..the EVO 5 (nice pic at the bottem of this post :P)
our best car, EVO4 became 2nd of 199 last rally (competing against 6 WRC's)
EVO 7
another Evo7
EVO 6
well, this also happens sometimes....evo 5...
and, a guy that has his own car, but uses our service.....also had a little accident EVO6
the cars (not al of them (testday))
Testday..the EVO 5 (nice pic at the bottem of this post :P)
our best car, EVO4 became 2nd of 199 last rally (competing against 6 WRC's
)EVO 7
another Evo7
EVO 6
well, this also happens sometimes....evo 5...
and, a guy that has his own car, but uses our service.....also had a little accident EVO6
06-07-2007, 03:34 AM
#18
0.5 BAR
Thread Starter
Join Date: Sep 2004
Posts: 175
Re: Why oh why is every turbo dead after about 600km....
i've got better video's of our own cars (onboard cam etc), but don't know a free server to upload video's. The X-trac sequential gearbox of the evo 4 is just music
06-07-2007, 03:56 AM
#19
0.0 BAR
Join Date: Feb 2005
Posts: 0
Re: Why oh why is every turbo dead after about 600km....
Originally Posted by Joseph Davis
You have some wierd oil feed issue, oil drain issue, or super hot EGT issue.
Turbos are simple, why the paragraphs?
ALS kills turbos, you should know this. Furthermore, why is a rally team on HMT asking why their turbos are dying?
Also
Originally Posted by Blohardt
I'm only suggesting checking the tune, you really can't tell how the a/f ratio is without a wideband lambda or an egt gauge, you really never know, especially when you run the motors that hard, they can change and most definitely vary from motor to motor, and the IAT's can change in a wink when you run a smaller turbo at the bleeding edge of efficency. If you want to monitor the exhaust gas pressure, why not just get a conventional MAP sensor and attach it to like a 6 ft coil of very thin copper tubing, which you can coil up and tap into the exhaust manifold. The air stack inside the tubing and the copper should dissapate the exhaust heat while still giving an accurate MAP reading, and I'm sure that can be integrated into the MOTEC. It seems like your ALS is pretty agressive, i've read that WRC cars usually use like 50 degrees btdc, and in light of the axial bearing wear, i would guess that the shaft is getting slammed pretty hard, and it could be the transition into the ALS is really punishing in this case. I would also venture a guess a pop off valve might be making the problem worse, because you're loading up the exhaust side heavily and totally unloading the intake side in the name of keeping the turbine speed up. But once again, you say you've got a perfectly working car with a more or less identical setup. I suppose clipping the turbine a little would be out of the question to reduce your backpressure a little, i would guess you need all the blade area possible with the restrictors you run and the torque produced. Just throwing a couple ideas out there.
06-07-2007, 04:18 AM
#20
0.5 BAR
Thread Starter
Join Date: Sep 2004
Posts: 175
Re: Why oh why is every turbo dead after about 600km....
oke, why am i asking these questions here, well simple reason, normally we always find the problem...this time it seems nowhere to be found. Especially since the car has almost the same setup as the rest.
We seem to overlook something...but what. HMT has helped me with my problems in the past, maybe...just maybe some people here know about turbo's......
Also, our rallyteam is NOT a professional factory team, we do compete with them ! (at least with the WRC's)
oke, we might have more equipment than most non pro teams....oke tru..im not going to lie, we do might have bigger budget than most non-pro's. But not even close to the budget of a factory team or some millionair teams.
ALS kills turbo's, i know, but its also makes it fast on the short tracks, hairpins etc etc. It kills turbo's but it has to stay acceptable. On a street car 2500-3000 km's isn't acceptable, in rally it is....
We seem to overlook something...but what. HMT has helped me with my problems in the past, maybe...just maybe some people here know about turbo's......
Also, our rallyteam is NOT a professional factory team, we do compete with them ! (at least with the WRC's)
oke, we might have more equipment than most non pro teams....oke tru..im not going to lie, we do might have bigger budget than most non-pro's. But not even close to the budget of a factory team or some millionair teams.
ALS kills turbo's, i know, but its also makes it fast on the short tracks, hairpins etc etc. It kills turbo's but it has to stay acceptable. On a street car 2500-3000 km's isn't acceptable, in rally it is....
