Pushing the LT4 fuel system and still holding....recent build.

[Redline MS]

Well finally after same "design" changes we where able to calibrate this 2015 A8 Z07 the other day. This car has our supplement fuel system but surprisingly we haven't needed to pull the cord yet. Cars moving over 100 lbs/min and we still have a bit more room for fueling. We capped it here for "competitive" reasons but we have some room for the growth we need. Learned a lot from this build especially after the factory Eaton goes bye bye...

Our goal was to not rape the factory functionality which most certainly added to figuring stuff out. Even the inlet pressure sensor is used in our new airbox.

No pain no glory! As soon as our new Redline Drag pack setup gets finished we are off to the track to squeeze this thing...

[SultanHassanMasTuning]

nice!!!

[Higgs Boson]

What fuel? My LT4 pump centri C7 runs out of HPFP at 4500 RPM on E70 (which is what comes out of the E85 pump).

Going to try E40 next when I get some time.

[Ben Charles]

I'm assuming 93 and meth with stock LT4 fuel hardware.
Higgs any more progress on your setup?

Howard is this a 2200 or YSI?

[Higgs Boson]

got the second lift pump on and have everything tuned except wot since i ran out of hpfp. hopefully all it takes is a lower mixture of ethanol to finish up. been too busy to get back at it.

[Ben Charles]

Cool... You try pushing it past 20 mpa? No experience myself, but I would try pushing it harder pressure wise and see what happens

[Higgs Boson]

i think it's set to 19 or so at the moment, it will run 19MPa until 4500 or so and start to drop off.

[Redline MS]

what fuel? My lt4 pump centri c7 runs out of hpfp at 4500 rpm on e70 (which is what comes out of the e85 pump).

Going to try e40 next when i get some time.

ms109.

[Redline MS]

I'm assuming 93 and meth with stock LT4 fuel hardware.
Higgs any more progress on your setup?

Howard is this a 2200 or YSI?

Its a 2200R

[Higgs Boson]

Tried E47 today and the dual lift pumps provide 65-70 psi all the way but rail pressure still drops like a rock around 4k RPM. :-(

[DSteck]

Tried E47 today and the dual lift pumps provide 65-70 psi all the way but rail pressure still drops like a rock around 4k RPM. :-(

Move your injection timing around.

[Ben Charles]

Higgs I know you've played with SOI some, when pressure starts dropping try making SOI start earlier in that area and see if you get commanded MPA back

[Higgs Boson]

Ok. I have it set to a max of 360 now, I will try 430 next and also and/or more pressure....19 now, will try 25.

[Higgs Boson]

430 SOI and 24MPa

pressure still falls off but not as sharply. around 4000 it starts to move down, gets to 13MPa by 5000, before it was 5 or 6.

whats the most anyone has tried for SOI?

I suppose earlier injection will be spraying on the closed intake valve, right? just like a port injected motor so maybe it won't hurt to try more.

any opinions?

[10_SS]

He's inside, it's dark, and he's wearing sunglasses...

[MikeOD]

I suppose earlier injection will be spraying on the closed intake valve, right? just like a port injected motor so maybe it won't hurt to try more.

any opinions?

Umm...it's direct injected...the injector isn't behind the valve.

[Higgs Boson]

duh.....

lol. i am REALLY reaching now!

my brain is on my 2016 mustang gt now I guess I picked up and have been messing with.

ANYways, does anyone want to figure on how early I might be able to start injection?

[LSChev]

I have been playing with SOI on a supercharged 6.2L 2015 Denali. It has a TVS2300 on it right now running approximately 7psi. I have noticed that starting it a tad earlier helps maintain rail pressure. Does anyone know what the theory behind this is?

Also slightly unrelated, if I change my SOI does that change the total injection time as well? Or does that remain constant?

We also have a supercharged c7 in the shop right now that seems to be experiencing similar issues to you (this one isn't making as much power though.) How quickly does your rail pressure drop? On this one it starts dropping around 4500 rpm and by 5500rpm its at 6mpa. Lift pump gives good pressure, we swapped the fuel pump with a known good one, same thing. Going to investigate a cam lobe/lifter issue tomorrow. I will let you know what we find.

[Redline MS]

430 SOI and 24MPa

pressure still falls off but not as sharply. around 4000 it starts to move down, gets to 13MPa by 5000, before it was 5 or 6.

whats the most anyone has tried for SOI?

I suppose earlier injection will be spraying on the closed intake valve, right? just like a port injected motor so maybe it won't hurt to try more.

any opinions?

I am still intrigued by the true differences between the LT1 and LT4 fuel system INCLUDING the electronic logic behind it... This particular car I just did stood up to 107 lbs/min of airflow and I still have some more room. It seems like you have been beating your brains out but seem to be doing everything in check. So question is....whats the difference?? Most certainly seeing cause and effect but something is missing here...

[Higgs Boson]

I have been playing with SOI on a supercharged 6.2L 2015 Denali. It has a TVS2300 on it right now running approximately 7psi. I have noticed that starting it a tad earlier helps maintain rail pressure. Does anyone know what the theory behind this is?

Also slightly unrelated, if I change my SOI does that change the total injection time as well? Or does that remain constant?

We also have a supercharged c7 in the shop right now that seems to be experiencing similar issues to you (this one isn't making as much power though.) How quickly does your rail pressure drop? On this one it starts dropping around 4500 rpm and by 5500rpm its at 6mpa. Lift pump gives good pressure, we swapped the fuel pump with a known good one, same thing. Going to investigate a cam lobe/lifter issue tomorrow. I will let you know what we find.

It helps maintain rail pressure because the injectors have more time to do their business so they demand less fuel per second (or millisecond or whatever period of time you want to use) so they are not draining the rails all at once. So yes, it does change total injection time at high load.....if you advance injection timing at idle or low load situations the car will run like sh!t.

I am still intrigued by the true differences between the LT1 and LT4 fuel system INCLUDING the electronic logic behind it... This particular car I just did stood up to 107 lbs/min of airflow and I still have some more room. It seems like you have been beating your brains out but seem to be doing everything in check. So question is....whats the difference?? Most certainly seeing cause and effect but something is missing here...

I think my big issue is ethanol. The car moves some air for sure, 81+ lb/min by 5000 RPMs, can't wait to see what it does at 7000 with 2 more psi built up....