Ok, so I'm not a turbo expert so I came here to see if someone can help with an issue?

changed my turbo to a Garrett GT3076 dbb a while back and when I went to get dyno tuned I had a bit to much knock (-4.00 deg @ 6,000 rpm) on fresh built motor, head and cams. The guy tuning the car was an expert engine builder, however, for the time I was there we couldn't figure out why the knock. Did a spark plug test and car was prematurely detonating.

What we did notice is that while the car was on the dyno, a bead of oil was coming from within the turbo inlet outward toward filter (while rpm was applied). I also noticed that my air filter (attached directly to the turbo inlet) gets wet with oil. My question is, what is causing this oil issue and could this issue be whats causing the knock problem? For instance, could oil be getting sucked into combustion chamber and causing the knock issue? Sorry again, I'm not an expert. Just trying to figure out this problem for awhile.

Thanks, Jason

 

Not sure on the turbo but maybe too high of oil pressure or not a large enough return line?

Oil in the intake will cause it to detonate and ruin the engine pretty quick, so fix the oil issue asap!

 

what kind of motor is it? may need an oil restrictor to the turbo feed to keep it from pushing by but the damage may already be done.

 

as mentioned before, if you turbo has ball bearing you going to have to restrict the oil flow, get with the manufacturer to figure out how much,,and oil on the intake side will cause detonation

 

Probably needs a restrictor since it's ball bearing. Also, if the air filter is too small the restriction will cause too much vacuum and suck oil past the seal.

 

The engine is a 2005 2.4L Dodge SRT-4 motor. Block is fresh built with 8:5:1 with 0.20 overbore. CNC ported head, oversize valves and crower stage 3 cams.


I have no clue if the turbo problem is related to the engine knock or not. Only other things I can remember is this:


When the tuner started the car he felt as though the engine was working hard to crank over. Because of that he wanted to do a compression test. He felt that maybe the compression was high and that was why the engine felt harder to crank over than it should. I think he said the compression was 200 which seemed to take him by surprise for some reason.


His partner was the one who noticed the oil beading out from the turbo while it was on the dyno. He said that oil may be entering combustion chamber. He checked hot pipe and no oil, cold side had some oil. Oil in cold pipe could have been from last setup though. He said to throw race gas in the car and do a log with lap top to see if knock improves. I put in 110 gas and the knock only seemed to improve just slightly.


Don’t know if that helps, but if anyone wants to offer suggestions on where should I begin a troubleshooting process to eliminate possible causes of oil in the inlet and if it relates to knock.


Thanks and Merry Christmas


Oh, and I will look into the oil restrictor.

 

That compression seems very high so i would double check the cam timing, seems like the cams are advanced or not degreed correctly and causing too much cylinder pressure. I doubt it has high compression pistons so that's why i say about the cam timing.

 

I agree, 200 psi cranking compression is WAY high for a boost motor. You say the head is CNC ported, are the chambers stock size or has the head been shaved? Has the block been decked? If the chambers and deck height are stock dimensions, then it almost has to be a cam timing problem, as testchimp says.

 

As said before, not really an expert on the technical side of it. I'm a mechanics best friend. As far as the chambers, if your referring to if the intake and exhaust ports, they were ported. I can also say that the tuner did adjust the cam timing so that the valves would overlap so it would lower the compression.... if that makes sense. He did a second compression test and it came to 190 after adjusting the cam timing. The biggest thing aside from the turbo spitting a little oil was the knock. Tuner just couldnt figure that out. He pulled all the timing he could and still got 4 counts of knock at 18 lbs of boost. I just dont know where to start. This whole think has been a nightmare trying to figure out.

 

It seemed that the more boost we added, the worse the knock got. I have a meth kit. Wondering if I install it would I be able to get more power with less boost. Another words, would if fix the knock issue. Guess that would just be a bandaid if it worked and not a resolution to the problem though. Gonna take the car to another local race shop and see what he thinks after new year cause hes closed till then.

 

Is this car intercooled? There are a number of things that will affect detonation, fuel octane, intake air temp, dynamic compression ratio, and timing curve. Changing any or all of these parameters can help with knock. Your meth kit will lower IAT, and boost octane at the same time. Adding, (or improving), your intercooler would help as well. To lower the dynamic compression will require changing your cam timing, (retarding cam timing lowers dynamic compression in the lower rpm range, detonation is lowered because of less time for it to occur the higher you go in the RPM range), or changing cams. In the past, I've used a system from Progressive Alky Control to make 28~30 psi on 89 octane on a built Buick GN motor with no knock. That car had a pretty good sized FMIC as well.

 

Thanks Rickracer, the car is inter-cooled and has a pretty large one. Had to remove the crash bumper just to fit it. I think that there can be much improvements in the cooling system and in the intake temps and I'm going to fix this within the week. I'm gonna have a good mechanic look over the other things that are beyond my knowledge and take the turbo off for inspections. Hopefully I will have this done before people get their income tax back and flood the shop. Sure would love to get to the point of being able to turn up the boost to 27psi.... maybe I should start building the spare engine I have incase it explodes lol. I will post up what I find. Thanks everyone

 

here you go... Tis is the main reason
the compressor creates a vacuum in front of the wheel, and it sucks the oil past the ring seal on the shaft
i used to put k&n filters on the front of my twins ( 57's, 66,72,76)
The 57's where journal bearing
all pulled oil with air cleaners on
all caused blue smoke on start up , on next qualifier/ next racing round
inside the intake tubing and manifold had oil coating

Clean it all out with brake cleaner.. Remove air cleaners.... No more oil
Btw, I run 80 psi oil pressure idle, 100 + through the lights.... Never had problem there with too much oil pressure....
have zero belief of restricter comments period.

 

The OP is using a ball bearing turbo. I've read a million times over that they require much less oil and usually use some sort of restrictor? I'm with you on journals. I run 80-90 on cold starts.

I think the compression may need to be recalculated.

For a refrence my 8.5:1 2.0 motor spits out around 145 psi of cranking compression. Cam timing can sway that cranking comp number either way by quite a bit, but yours still seems really high. It would explain the detonation issues anyway.

OEM B16 honda engines are 10.2:1 and cranking compression was 200-210 or so on my stocker.

 

Ok, with the bb comment,
why does that statement Not come in writing from turbonetics?
And when talking to the engineers , they have never told use to put a restricter on the line?
and
if you look down inside the oil feed , it has a smaller hole that branches to each end of the bearing housing
personally I don't buy the restricter stuff...
Parts will tell you what it wants, and restricters are just a bandaid to other problems
i stand corrected if info from the manufacture shows different

 

I dunno, I suppose most if not all turbos have a recommended oil pressure min and maximum. I know the BW stuff does. If you need a restrictor to fall into that window then so be it. BW even goes into depth on the supply and drain sizes for most models if you dig enough. My Holset HX40 states it requires a minimum 19cm ID drainline!

Garretts Q&A section...


http://www.turbobygarrett.com/turbobygarrett/faq

 

Fair enough,
never been on Garrett site... Never buy their stuff

 

They require a 7.5" drain line? lol, I think you meant 19mm. Also, how can you verify the oil pressure after a restrictor? Given enough time, any leak with equalize pressure on both side of a restriction. If you have 90psi, putting a .040 restrictor won't magically make you have 40psi on the other side if there is enough time for the pressure to equalize. You would have to have a pressure gauge between the housing and the restrictor in a line or something to even be able to measure this. Putting a restrictor in the fitting at the housing and calling it good is no better than not running it at all if you don't know how it affects total pressure.

 

hah! Yes 19mm. One of them dern foreign measurements. Ended up using 3/4 ID copper pipe and sweated most of it together.

I believe the restrictor is more to limit overall volume. With a journal cartridge I think as long as you don't overload your drain your good. You'd have to ask garrett about there 40-45psi operating window...

My Holset HX40 is a journal bearing. This is right out of the manual...

 

I'm yet to see a restricter on Garrett tv, tl , s400, s4d, t18, holset turbos on cummins, cat , komatsu , Mack, engines...