Is meth injection effective at keeping the valves clean?
 

Still trying to decide which way to take my build. I dont like the idea of upgrading heads and then having the valves crapped up do to the DI.

Does meth inject enough to keep them clean or do I have to go to port injection to really be effective?

I am sure it "helps", but only so much from a nozzle system. When you put a nozzle or dual nozzle on it really isn't getting evenly distributed to all cylinders.

So I'd say yea it probably helps some, but direct port meth or port fuel injection would be the ultimate way to ensure each cylinder is getting washed so too speak.

How much coking damage occurs to GM engines that are Direct Injected? Since they started delivering cars with DI engines in the 2007 or 2008 model year there doesn't seem to be a big issue. Very few cases if any have been reported on a lot of engines produced.

Bill

My question isn't about damage. If I'm doing a performance build and spending $10K+ on heads/cam/rotating assembly, I want to maintain the performance. If undercutting valves and doing multi-angle valve jobs can have a noticeable improvement in performance, what does having valves that look like this do for performance?

https://cimg7.ibsrv.net/gimg/www.cor...b128357e05.jpg

My point was that seeing valves like that on GM DI engines is rare. GM and Ford don't seem to have the problems other manufacturers are having and have a history showing very few complaints about valve coking in their DI engines. From what I have read in various articles that is due to the timing of when they inject the fuel in relationship to the valve opening. I imagine a tune could screw that up if the tuner doesn't understand all the mechanics of what is happening inside the cylinder.

Here is a quote from one one article I found:
"GM has addressed the buildup problem by altering fuel injection timing and valve opening timing. If too much fuel is injected during the intake phase when the intake valve is open, the high cylinder temperature can cause the fuel to contact the intake valve and form soot. Once soot accumulation starts, it builds rapidly. So GM changed valve and GDI injector timing to reduce the contact time and prevent soot formation.

The industry reports that GM and Ford engines are among the least affected by carbon buildup problems in their GDI engines.

On other brands, the amount and severity of buildup is directly related to the quality of the fuel, driving habits and engine operating temperatures. GDI engines that encounter lots of short trips and cold starts tend to have more problems with carbon buildup."

You need to make sure you are solving a problem that you might encounter before spending money on a solution.

Bill

Definitely agree with you there. What I can tell you is that I looked at my valves at 5000 miles and there was already build up. Not horrible, but definitely there and more than you would see on a 100k mile LS. I'm now at 25000miles and I will take a closer look when I do the build. It does not initially appear to me that it will be a non issue over the long term.

Then, even if GM reduced it with injection and valve timing, what does installing a stage 3 cam with more overlap do? What does putting a phase limiter on do? How about tuning injection for significantly higher power? I would absolutely bet that makes the problem worse, not better.