[PeteSS2018]

So given the range of options out there, I'm interested to know in summary what people think is the best approach to fuelling at present. My 2018 is still stock fuel & internals, with 2.9L Whipple on a safe tune.

I'm thinking of going to GPI drop ins, more boost and some peripheral mods like oil pump, DOD delete & new lifters. But fuel is the big question and I'm currently trying to toss up essentially 3 options:

1. LT4 fuelling with overdriven cam lob & ++% injectors, with improved low side (DSX or Fore)

2. DI Goliath or Lingenfelter HPFP and improved low side (DSX or Fore)

3. LT1 DI left as is, supplementary Port Injection with THPSI full kit + low side (either separate in line pumps or combined with improved Low Side pump)

All seem to have pros and cons. Ideally I'd want enough fuel to future proof for up to 1,000hp on 93 (no plans to run E60/85 etc here). I'm not sure that a LT4 HPFP can actually get there, so that might rule out that option.

I'd appreciate what else anyone thinks is really the best approach to a full fuel system ...

[Joshinator99]

Originally Posted by PeteSS2018

So given the range of options out there, I'm interested to know in summary what people think is the best approach to fuelling at present. My 2018 is still stock fuel & internals, with 2.9L Whipple on a safe tune.

I'm thinking of going to GPI drop ins, more boost and some peripheral mods like oil pump, DOD delete & new lifters. But fuel is the big question and I'm currently trying to toss up essentially 3 options:

1. LT4 fuelling with overdriven cam lob & ++% injectors, with improved low side (DSX or Fore)

2. DI Goliath or Lingenfelter HPFP and improved low side (DSX or Fore)

3. LT1 DI left as is, supplementary Port Injection with THPSI full kit + low side (either separate in line pumps or combined with improved Low Side pump)

All seem to have pros and cons. Ideally I'd want enough fuel to future proof for up to 1,000hp on 93 (no plans to run E60/85 etc here). I'm not sure that a LT4 HPFP can actually get there, so that might rule out that option.

I'd appreciate what else anyone thinks is really the best approach to a full fuel system ...

You can do 1000 crank HP (850+ WHP) on 93 with DI only without trying too hard. My LPE DI setup below does that no problem. You’ll need lower compression pistons and the GPI drop in setup works great, I did those as well. The GPI setup is amazing and takes a pounding.

If you want to make 1000 WHP, you need more octane so E is the best way to do that although 100+ octane race gas could do as well but E is easier to deal with, cheaper to operate, and a flex sensor makes it cake since it’ll automatically add timing as your E content goes up.

Port injection has gotten so much easier and cheaper that it’s the best bet now since it helps “future proof” your setup. Wish I had done that out of the gate.

[PeteSS2018]

Originally Posted by Joshinator99

You can do 1000 crank HP (850+ WHP) on 93 with DI only without trying too hard. My LPE DI setup below does that no problem. You’ll need lower compression pistons and the GPI drop in setup works great, I did those as well. The GPI setup is amazing and takes a pounding.

If you want to make 1000 WHP, you need more octane so E is the best way to do that although 100+ octane race gas could do as well but E is easier to deal with, cheaper to operate, and a flex sensor makes it cake since it’ll automatically add timing as your E content goes up.

Port injection has gotten so much easier and cheaper that it’s the best bet now since it helps “future proof” your setup. Wish I had done that out of the gate.

Appreciate your comments. So 10.5:1 GPI's I assume?

Re fuel, I'm tending towards THPSI/Reflex which seems to work without too much trouble, and as you say gives head room for future changes. And I like the idea of keeping the LT1/DI for efficiency when operating in lower RPM range.

*** Mind you, not sure with port plates it'll all fit under the OEM hood. THPSI say that it'll raise the S/C lid height by 0.8" so even though that seems like a minor concern, my goal is to keep it looking very clean so big hood bulges etc aren't what I want! I'll check the clearance in the next few days.

[Joshinator99]

Originally Posted by PeteSS2018

Appreciate your comments. So 10.5:1 GPI's I assume?

Re fuel, I'm tending towards THPSI/Reflex which seems to work without too much trouble, and as you say gives head room for future changes. And I like the idea of keeping the LT1/DI for efficiency when operating in lower RPM range.

*** Mind you, not sure with port plates it'll all fit under the OEM hood. THPSI say that it'll raise the S/C lid height by 0.8" so even though that seems like a minor concern, my goal is to keep it looking very clean so big hood bulges etc aren't what I want! I'll check the clearance in the next few days.

You’re welcome! Yes, the GPI “lower compression” setup is what I run. I think I’m closer to 10:1 since I have aftermarket heads with slightly bigger combustion chambers too.

The Whipple 2.9 can be drilled for port injectors and it’s even easier on the Whipple 3.0 since it has removable runners that can be drilled out for port injectors (Whipple even casts injector bosses into the runners). Crawford Racing used to do the 2.9 port modifications, not sure if they still do. Might be better than messing with plates.

[KingLT1]

You will run into octane limitations at 1000hp with 93.

[radz28]

Originally Posted by PeteSS2018

Appreciate your comments. So 10.5:1 GPI's I assume?

Re fuel, I'm tending towards THPSI/Reflex which seems to work without too much trouble, and as you say gives head room for future changes. And I like the idea of keeping the LT1/DI for efficiency when operating in lower RPM range.

*** Mind you, not sure with port plates it'll all fit under the OEM hood. THPSI say that it'll raise the S/C lid height by 0.8" so even though that seems like a minor concern, my goal is to keep it looking very clean so big hood bulges etc aren't what I want! I'll check the clearance in the next few days.

I can't recall what cutting (if any) has to be done for your Whipple/SS, but your best bet of fitting PI Plates (if you don't drill-out the runners, as Josh' pointed out) are probably THPSI'S new KATANA plates, which are as short as they get, to my understanding.

[PeteSS2018]

Originally Posted by KingLT1

You will run into octane limitations at 1000hp with 93.

Thanks, so are you saying there is no solution that gets 1000hp that doesn't involve E blended fuel? Is that specifically due to detonation issues at higher RPMs & boost?

Doing more reading, it seems like the alternative of Katech Goliath + Low Side + Injectors might actually be a more straight forward install (price wise I'm not sure sure yet compared to PI). Especially here in Australia where tuning LT1's is not a common thing, let alone proper integration a PI controller/fuel system with the LT1 ECM.

Left to it yourself KingLT1, would you go down the DI or the PI path?

[KingLT1]

Meth injection or race fuel. You don't need PI if running pump gas with meth injection or race gas. LT4 fueling is sufficient. PI is the easier way to go for big power on E85.

[Sillysspeed]

Gpi just did a c7 very similar to what you are wanting. Think it made just over 1000hp with pump gas and meth injection.


Lt4 injectors and hpfp. Dsx low side system and a direct port meth system driven by and alky controls pump and controller

[PeteSS2018]

Originally Posted by Sillysspeed

Gpi just did a c7 very similar to what you are wanting. Think it made just over 1000hp with pump gas and meth injection.


Lt4 injectors and hpfp. Dsx low side system and a direct port meth system driven by and alky controls pump and controller

Unfortunately here in Nanny State Australia, meth/water injection is generally not legal for street use.

I'm looking for a solution that can make 1,000hp on 93 (it's actually called 98RON here in Aus).

[Katech_Mike]

Originally Posted by PeteSS2018

Unfortunately here in Nanny State Australia, meth/water injection is generally not legal for street use.

I'm looking for a solution that can make 1,000hp on 93 (it's actually called 98RON here in Aus).

~950-1,000bhp(800-850RWHP) can be done with 93 octane. Low side, LT4 HPFP, and +30% Injectors.

[Joshinator99]

Originally Posted by Katech_Mike

~950-1,000bhp(800-850RWHP) can be done with 93 octane. Low side, LT4 HPFP, and +30% Injectors.

Along with lowered compression I would add. As posted above previously, I’ve already done this.

[18.2SS.1LE]

Add Boostane for more knock protection, doesn't run much with the Professional version. I add 4-5 ounces per tank for peace of mind. I am out of fuel with the LT4 fuel system though, as stated above you would need more injector.

[SOCAL.M6.ZLE]

Originally Posted by Katech_Mike

~950-1,000bhp(800-850RWHP) can be done with 93 octane. Low side, LT4 HPFP, and +30% Injectors.

I agree, talking with many tuners... (lots of different opinions) but from what I have distilled... Maxing out Di has alot of benefits, and makes more power. Justin White has made almost 1K wheel, on Di only (not even max effort)... and agree's you make more power on Di only.

For me, I like the idea of doing a low side (drop in our aux) cam lobe + HPFP and some 30-50+ XDI's for the win...

You will find there are more opinions than options. Good luck picking one.
In short, I suppose the PC answer might be, consult your tuner, and find out what combination they have confidence tuning. Or, find a tuner that has experience tuning the combination you desire. Forcing one against the other only seems to lead to frustration.