Direct Injection What's on your mind??
On The Tree
Joined: Mar 2012
Posts: 131
Likes: 2
Valve debris build up is a result of gasoline boiling on hot backside of intake valve, how is a catch can going to solve this problem. FYI the Audi RS4 already has a very exotic air/oil seperator circuit in its crankcase ventallation system. Oil vapors are not the cause of this problem.
Valve debris build up is a result of gasoline boiling on hot backside of intake valve, how is a catch can going to solve this problem. FYI the Audi RS4 already has a very exotic air/oil seperator circuit in its crankcase ventallation system. Oil vapors are not the cause of this problem.
On The Tree
Joined: Mar 2012
Posts: 131
Likes: 2
It's called REVERSION and happens during valve overlap between the exhaust cycle and intake cycle when both valves are open, you get some travel of the fuel air mixture from the combustion chamber to the intake port. On high performance motors with long duration cams, you can see the effects of reversion into the intake manifold. Some of this can be cancelled out with injector timing and runner tuning but, like I said on a high performance motor like the B7 RS4 this build up is a major problem in the long term. For a motor with short valve timing it isn't as great a problem, for my Duramax truck it isn't either but for gasoline fuelled cars, this problem hasn't been fully addressed.
I think direct injection for gasoline is fantastic, I can't wait until gen 5 and when aftermarket parts become a little more mainstream. Power potential for DI is massive in stock form, but when the fuel system capacity is exceeded, expect those modifications to dwarf all other vehicle costs...
Also worth a mention, PCV is going to need a complete redesign. I've never seen Audi's version, but I'm sure its exotic for a reason. Someone correct me if I am wrong, but if new-generation DI gas engines are anything like a diesel, they won't have a throttle body and therefore no vacuum... There would need to be some sort of vacuum pump to pull fresh air through the engine.
The valve debris problem is an interesting one...looking forward to progress on a fix for that.
Also worth a mention, PCV is going to need a complete redesign. I've never seen Audi's version, but I'm sure its exotic for a reason. Someone correct me if I am wrong, but if new-generation DI gas engines are anything like a diesel, they won't have a throttle body and therefore no vacuum... There would need to be some sort of vacuum pump to pull fresh air through the engine.
The valve debris problem is an interesting one...looking forward to progress on a fix for that.
TECH Senior Member
Joined: Jul 2009
Posts: 8,034
Likes: 663
From the articles I've seen, the DI pistons are drastically different than what normal pistons look like. I am sure when GM does interdue the DI V8, they will have to use torque management to keep their trannys (& rest of the drivetrain) under warranty.
On The Tree
Joined: Dec 2004
Posts: 124
Likes: 0
From: Northville, Michigan
The DI system used by Corvette Racing three years ago operated in the 1250 psi range.
DI is given credit for 10% to 15% increase in power. 91 octane production cars from Europe are running 12.5 to 12.8:1 compression ratio.
I believe that in two to four years we will see aftermarket heads which have incorporated OEM Direct Injectors. Packaging and driving a pump will be interesting.
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Last edited by Pumba; May 11, 2012 at 06:21 PM.
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Like posted above it will be $$$ to modify. The oems are waiting on electrical operated valve tech(solenoid) to fully go this route. Imop. We shall see. The Gen 5 V6 Camaro is already DI. They have N20 kits out for it. So the aftermarket is embracing it some.
