Direct Injection = Carbon Buildup?
Anyways... we started discussing some of the issues he sees there with the high end cars and we ended up talking about the necessary maintenance the audi's (or any there with DI) need just about every 25k-30k.
Basically, the carbon buildup is so bad that the top end of the engines are replaced FREQUENTLY under warranty.
So, I got to wondering if the new LT1 will also suffer from this and what could be done to avoid it. Some of the Audi guys run 100% meth and they still see carbon build up. You can read threads after threads about this and basically, they take the mani's off every 5k miles and clean them.
Your thoughts? Maybe Big Gunz's can chime in? Or not.
I guess time will tell then.
I have some pictures for you guys
I'm a tech at BMW and I myself am worried about the DI in the vettes. Obviously the issue is going to be on the intake valves only. You have no fuel running over the valves due to direct injection. But.....the saving grace may be the non forcefed application and you may not have the blowby that we do on the twin turbo (n54) engine
Pictures are from a 07-08 335xi
You mean like this ? ? ?




For reference this is what it should look like prior to lapping
Last edited by MyFirstLS1; Dec 30, 2012 at 02:33 PM.
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Go take a look on the BMW forums and ecotec forums. Carbon build up is a real issue my friend. Just because a manufacture continues to build something doesn't necessarily mean that the all the issues have been dealt with. I.E. the LS7 or the Audi's DI engines.
Hopefully the vacuum pump (in the LT1) will help pull the oil coming through the pcv out of the intake tract enough to reduce any significant carbon buildup.
It almost needs another set of inectors just for cleaning purposes like the style thats currently in use. I'm sure they can figure out a way to cut out the DI and run off them but I don't see that happening.
Interesting read.
MYFirstLS1: Tell me about it. I have seen these engines in person before and its crazy the gunk that comes off the intake tract. What I find comical is the idea the car manufactures are still producing these engines as to assume that the problem is resolved. Some are introducing a secondary injector back into manifolds to wash the valves off.
Again, hopefully GM has considered the issue and the pump will help instead simply adding another service item to keep their service departments busy.
All the new turbo direct injection motor use a new style injector but I have yet to come across this issue with the new style single twin scroll turbo cars n63tu ttv8 or n55 single twin scroll straight 6
Haven't seen anything like that at least from BMW (as far as a secondary injector)
The ones I've seen have been the Audi/VW engines and I was just amazed considering the miles the engines had.
I read in one of those mbboard threads about Porsche adding an injector however I haven't seen found anything related to it. That may just be a rumor for all we know.
PCV-integrated rocker covers: One of the most distinctive features of the new engine is its domed rocker covers, which house the, patent-pending, integrated positive crankcase ventilation (PCV) system that enhances oil economy and oil life, while reducing oil consumption and contributing to low emissions. The rocker covers also hold the direct-mount ignition coils for the coil-near-plug ignition system. Between the individual coil packs, the domed sections of the covers contain baffles that separate oil and air from the crankcase gases – about three times the oil/air separation capability of previous engines.
-Perhaps those baffles and new pcv system will help keep the intake ports/valves clean.
The head that is pictured has 90k but I have seen one with 25k just as bad
But like I said it may be OK since it won't be turboed
Last edited by MyFirstLS1; Dec 30, 2012 at 08:11 PM.
This is really the true measure of progress isn't it? As the engines get more complex, the servicing also becomes more involved. BTW - I'm not worried about the expense, I'm worried about more stuff in tight spaces and the resultant cuts and bruises from the work. Its getting more and more to the point where you have to pull an engine to do anything on it.
The MB engineer stated in that thread that they were not aware of such a problem. Do you have that much faith?
I ALSO hope that the engineers working on the new lt1 found a way around this but one thing is the engineers time and costs associated dealing with the problem and another are those that pay the bills which dictate what.gets fixed and what gets left for us to deal with. The percentage of failures versus overall production numbers play more into all of this then we would like, including the engineers.
If anything, I'd be more worried about problems no one has seen before.






