2018 G.M.C. Sierra L86 Fuel System Mods to Support 800 whp on E85

[Tapout Tuning]

We normally build and tune late model twin turbo V6 Cadillacs, and don't have much experience working on V8s. Wondering if we could solicit some fuel system advice from this group.

Currently considering our options on a 2018 G.M.C. Sierra with 6.2 liter L86 engine. We've added an Armageddon twin turbo kit, with upgraded LPFP and LT4 fuel injectors. Currently running boost at 7 psi and it makes 585 whp on 93-octane pump gas.

We're thinking about upgrading the pistons and rods, installing a cam with fuel lobe, switching over to E85 and increasing the power up to ~ 800 whp. However, we can't seem to locate a LPFP fuel pump that will support this power level on E85. And we also haven't found any sort of HPFP internals upgrade kit. Are these mods a thing for this platform? If not, what are others doing in order to support ~ 800 whp on E85 with these trucks and similar LT4 powered vehicles?

Thanks in advance!

[Estep40511]

Look up Late Model Racecraft in Texas. They have a twin turbo kit for Silverado L86 running low boost and can make 1000 hp, probably close to what youre trying to do. They could give you some info as to what they are using for fuel. good luck!

[32vape]

Lingenfelter makes a big bore pump and larger injectors. Katech has injectors and a secondary hpfp setup and fic also has injectors. I've had experience with all that stuff and have landed on added port injection is the way to go. Data on the injectors is only so so and the larger fuel lobes are starting to show accelerated pump wear in stuff that's driven hard. I went through an lt4 pump in a summer with a 38% lobe. Crawford Racing, Modern EFI, Too High Psi have port systems. And most are using the Too High Psi port plates.

[Tapout Tuning]

Appreciate the information guys!

[MORLOK]

Mast also makes port injection intakes.
Really hard to beat for the price, comes with intake, injectors, and rails.
https://www.mastmotorsports.com/coll...take-manifolds

I am running their L84 intake on my L83 truck, with MS Pro fuel control.

The downside with secondary fuel is you have to fool the MAF so you don't run out of stock injector. This throws off the cylinder airmass calc which affect spark control. This seems manageable on system that still uses the stock injectors for most of the fuel supply, but on high HP builds, where more than 50% of the fuel is from the secondary system, it would be more of a problem. I think the solution at that point is to use the secondary computer to run spark control also.

The other great thing about the secondary computer is you can run closed loop boost control and wide band close loop WOT fuel control.