Quote:
Originally Posted by MadMaxx
It works no differently on DI than anything else...you aren't running anywhere near high enough static CR to predet (without knowing how aggressive timing is, kinda hard to really get into details) 93-120 octane fuel (pump/meth) Direct injection gives a higher fuel delivery granularity, and as a byproduct a higher static CR and lean condition can be achieved.... but all the rest of the monitoring and correction systems are there. If knock is detected, timing is pulled, just like anything else (actually, at a much faster sample rate since DI has awesome monitoring capabilities).
Don't overthink the system  If you need current examples, check w/ the VW guys. The LS/LT 3.6L DI camaros already have wet nitrous kits available (50-100hp) from ZEX. |
I am not disagreeing that you can get it to work. I just don't think at 11.3:1 compression you should be dumping fuel into the engine with a fogger while under boost. I also don't think a Zex nitrous system is apples to apples, since it is shoving fuel and oxygen into the system together, and the Zex setup actually keeps it electronically balanced. Normally the stock PCM balances it, but they are probably running a 1-bar MAP (anyone know for sure?). I am not saying you can't get it to work, I am saying that it will work best if you can keep it in the stock PCM, which means you need a stock fuel system that can support the power.
I can't wait until somebody gets a system going. The fact is that we are in uncharted territory on these cars. I usually go conservative in these situations.
Quote:
Originally Posted by Baldturbofreak
Geoff, when you are WOT, the DI system operates like a PFI system.
IT injects fuel during the intake stroke to create a homogenous charge.
The benefit of DI when in this mode is the reduced droplet size from 2200psi, and the latent heat of vaporization occuring within the chamber.
Adding up to 30% fuel upstream will change nothing while in this mode of operation. Nor would 30% of proper AFR be ignitable.
Only in a few light light loading situations(and low rpm too) does the system actually wait until the comrpession stroke to inject fuel.
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It should work by theory then, so who is going to be the first gunea pig? I still think best case is when the PCM is controlling ALL the fueling. I wouldn't buy a turbo kit that required me to spray fuel into the intake, but that is just me. It is one thing to spray meth to cool the charge, but spraying fuel because your stock system is overwhelmed is not for me. It can definitely be done, but I wouldn't put a setup like that on my daily driver.
Quote:
Originally Posted by Baldturbofreak
I have a copy of the bosch DI manual, there are 7 distinct modes of DI. It's enough to make your head spin.
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Which is exactly why I still say (in my previous post) that the stock fuel system is going to set the baseline for how much power a bolt on turbo kit can make. Because once you add fuel outside the stock system, the PCM is marginalized in how well it can control the rest of the engine. I am not familiar with the modes of DI, but being in boost is going to change the operation of the system dramatically. The things that trigger the modes are going to be different in a boosted car. And spraying fuel outside of the PCM that controls those modes IS going to affect it's behaviour. The question is how? And the answer is that we don't know yet (at least I don't).
Yea, you can throw some hobbs switches and start dumping fuel into the intake. But for me, the only fuel I am putting in is going through the factory system, or at least a something close to it (like bigger injectors or something).
-Geoff