[b1anc0]

I am running stock bottom end LT4 with +38% fuel lobe cam together with Maggie 2650 on top. My pulleys are stock (90mm) upper and 15% lower. In addition to that I have all the supportive mods: 103mm TB, Rotofab Big Gulp CAI and DSX aux pump.

Currently, my car is tuned for 93 octane, but I would like to add some E (probably E50-60, not going to run full E85) to get some cooling and more power.

As I understand, in order to do this I have 3 ways:

• Methanol injection
• Port injection
• More productive injectors & HPFP

My goal is to keep the build as simple and clean as possible, so I lean towards the injectors plus HPFP combo.

I do understand that in terms of budget it isn't the most wise and efficient choice, but I have to consider the installation complexity as well, since in my country we don't have so much experience and expertise with these engines.

Taking all above mentioned into account I would like to ask you guys to educate me a bit regarding the injectors and HPFP variety. From what I currently see there are a few options for injectors and HPFP:

Injectors

• FIC GDI LT1/LT4 High Flow +30%
• XDI LT4 +30%
• XDI LT4 +50%
• XDI LT4 +70%

HPFP

• LPE Big Bore
• Katech Goliath (currently in development)

I've made some investigation and discovered that there are different variations of combos available, for example - FIC +30% with LPE Big Bore, XDI + 70% with LPE Big Bore etc.

Which combo from the above list would be the best? What are your suggestions? Would any of the above-mentioned combos handle E50-60 for my build spec?

[KingLT1]

I would probably go with the +50 and LPE HPFP. If you do the +30, then they run out of headroom before the LPE HPFP, If you do the +65, the LPE HPFP runs out before the 65's. Hence why LPE probably offered 52% injectors with their pumps for years. I have tuned 3 cars with LPE HPFP and +65's with 38% cam lobes, and the HPFP starts to get unstable when the injectors still have plenty of room left. Thes are 950+whp cars running E60-70.

I would say with DI only fueling plan on E50-60 and don't worry about trying to run more. It's all you need anyway, just have to blend which isn't a big deal.

[Joshinator99]

Originally Posted by KingLT1

I would probably go with the +50 and LPE HPFP. If you do the +30, then they run out of headroom before the LPE HPFP, If you do the +65, the LPE HPFP runs out before the 65's. Hence why LPE probably offered 52% injectors with their pumps for years. I have tuned 3 cars with LPE HPFP and +65's with 38% cam lobes, and the HPFP starts to get unstable when the injectors still have plenty of room left. Thes are 950+whp cars running E60-70.

I would say with DI only fueling plan on E50-60 and don't worry about trying to run more. It's all you need anyway, just have to blend which isn't a big deal.

Agreed, and my experience with the LPE HPFP & +52% injectors has been exactly what you said. At 2175 psi rail pressure, +32% lobe, and E50, I put down 1059 WHP and I’m definitely out of steam. If I even try to raise the rail pressure at all, it gets unstable. If I try to run E60, it gets unstable. So 950 WHP at E60-70 sounds right on with a +38% lobe.

Great info as always King.

[CamOnlyJabroni]

Originally Posted by Joshinator99

Agreed, and my experience with the LPE HPFP & +52% injectors has been exactly what you said. At 2175 psi rail pressure, +32% lobe, and E50, I put down 1059 WHP and I’m definitely out of steam. If I even try to raise the rail pressure at all, it gets unstable. If I try to run E60, it gets unstable. So 950 WHP at E60-70 sounds right on with a +38% lobe.

Great info as always King.

Sounds exactly like what my ZL1 is doing. Only mine is less power so it can run E60 but if I try to run E70 it gets unstable up around 6,500rpm. My vette is stuck on E50 like yours is. I scored a XDI XFP 3600 belt driven HPFP setup for $1,200 bucks I’m going to put on it. Hopefully I can go from E50 to full E. Would like to run full E if I can just for peace of mind since it’s tuned a little spicy.

[Joshinator99]

Originally Posted by CamOnlyJabroni

Sounds exactly like what my ZL1 is doing. Only mine is less power so it can run E60 but if I try to run E70 it gets unstable up around 6,500rpm. My vette is stuck on E50 like yours is. I scored a XDI XFP 3600 belt driven HPFP setup for $1,200 bucks I’m going to put on it. Hopefully I can go from E50 to full E. Would like to run full E if I can just for peace of mind since it’s tuned a little spicy.

I know there’s been a bunch of issues with that pump so I’d be checking it frequently… at that price I don’t blame you for trying it out and hope it works! I keep waiting for DSX to launch his system but it’s taking forever…

[b1anc0]

Thank you for the valuable info, guys! Really appreciate it!

Just to clarify: +65% injectors are those offered by XDI, right? I currently see only +70% offered by XDI and Katech. I assume they are the same.

Also, what is the approximate difference between E50, E60 and E70? I think that at some point (maybe E60) there isn't much difference in comparison with going full E?

[Joshinator99]

Originally Posted by b1anc0

Thank you for the valuable info, guys! Really appreciate it!

Just to clarify: +65% injectors are those offered by XDI, right? I currently see only +70% offered by XDI and Katech. I assume they are the same.

Also, what is the approximate difference between E50, E60 and E70? I think that at some point (maybe E60) there isn't much difference in comparison with going full E?

Believe the XDI +65% injectors were superseded by the +70% versions.

I’d guess guess it probably takes a good 10-15% more fueling capacity to run E85 instead of E50. E50 gets you virtually all of the benefits of E85 but less fuel system strain. Great if you can run full E though.

[KingLT1]

Originally Posted by b1anc0

Thank you for the valuable info, guys! Really appreciate it!

Just to clarify: +65% injectors are those offered by XDI, right? I currently see only +70% offered by XDI and Katech. I assume they are the same.

Also, what is the approximate difference between E50, E60 and E70? I think that at some point (maybe E60) there isn't much difference in comparison with going full E?

Yes +65 were discontinued.

I would say 15whp difference on most builds under 1000whp going from E50 to 80.