Those are some good numbers for tune and exhaust only. The 07-13's were what, mid 15's on a 5.3L with similar mods?

 

Yeah I hear you there, but Id probably wait a while until the aftermarket catches up so I can buy one, mod it, and lift it the way I want.

Good numbers though without a doubt.

 

before people go off the deep end and think 25% idc is low. not exactly on a direct injected engine. Your main concern is Msec. The window of time you have to complete the injector pulse before you miss the window and throw a mis-fire code. So in theory, no you do not have a lot of room to mess with with aftermarket mods and such without doing a larger fuel lobe, or secondary injector setup to compensate for it.

 

Interesting, I am gonna have to read up on these.

 

Has anybody started on LT's for this truck yet? Cant wait to see how a single cab, 6.2 runs on the 1/4!

 

Very interesting... I hadnt thought about it but it makes complete sense. When I first heard of the injector size I was pretty shocked, but this totally puts it in perspective. I wonder if the fuel pumps are any bigger too.

Thanks for that post... great info.

 

the in-tank pump just serves as a lift pump in the GDI setups. feeds the hpfp, and the pressure gets jacked to 2k+ psi for the precision injection purposes. good way to watch and see if you're out of feed pump or not is if the fuel pressure drops on the top end. if you're out of hpfp, you will lose pressure in the midrange.

 

so fuel pressure at the fuel rails... or whatever they are called now, is 2k PSI?

There is a primary pump similar to what we have now, and a secondary high pressure pump that jacks it up to this level?

 

Low pressure from the tank to before the rails(very similar to what we have now), then there is a camshaft driven mechanical high pressure pump that boosts the normal low pressure up to over 2,000psi. This is a hoigh pressure, but not approaching diesels very high pressures.


And yes, we cant compare IDC from DI injectors like we can with Port Fuel Injectors.
DI uses a multitude of different fueling strategies. Instead of spraying fuel at the cylinder head wall and intake valve, DI actually draws its heat from the air itself, this is what allows the higher compression ratios compared to PFI.
DI doesn't usually spray fuel the entire time the intake valve is open, it breaks injection up into many events. It might squirt a bit just as the valve opens, then more a few milliseconds later, and then maybe more just before the plug fires. It simply doesn't spray the entire fuel load in one hit. The timing is incredibly precise.

The limiting factor is the injectors. IIRC the GEN V LT1 uses a 125 lb/hr injector.

The Chev Indycar 2.2 liter V6 revs to 12,000 rpm and uses direct injection as it primary fueling, it also is twin turbocharged which necessitates conventional Port Fuel Injectors as well. The engine runs on E85.

There are some exciting engines coming down the pipe. LT4 is one of them. Yeehaw!

peace
Hog

 

also, when tuning these things. Normal port injections air fuel/lambda's do not apply. on average between the two is about a point leaner. Take the turbo cobalts for instance. I run them and make the best power at 12.6-12.8 afr on 22-27 psi with zero issues. Even on larger turbos. e85, i run them at 13.0-13.2 on the same boost levels. So it shouldn't be uncommon to see afr's in the low to mid 13's at wot.