[JSH]

Originally Posted by KingLT1

Or if you change the cam then get a 42% lobe, big bore, and +65's.

LPE referred me to this cam
https://www.lingenfelter.com/PROD.ht...5#.YnmNwejMJMs

I do not see a 42% on their site, but I'm probably just missing it.

[KingLT1]

LPE rates their fuel lobe in MM. The 7.85mm is 42%.

[shinysun]

Is it Ok to use 2900PSI with LPE big bore? The homepage is saying "Never exceed 15 Mpa", 2150psi.

[Chrome383Z]

The LT1 pump is rated for 2175 I believe and the LPE is based on it. I’m not exactly sure what all they do but I believe it’s bored out and maybe machined deeper for increased stroke. Folks on here have ran them at higher pressures and I haven’t read of any failures but always a chance of pushing things closer to that edge.

However I haven’t seen anyone get good results cranking the pressure up, flow drops off. The LPE pump flows 10% more at 2150psi then the LT4 at 2900psi. So ideally you’ll want to run at the rated pressure.

Just have to make sure you have enough injector at the lower pressure if that makes sense. Example an LT4 injector at 2900 psi may flow similar to a +30 at 2150 psi. That’s why I bought +30 with my LPE pump. Figure I’m going to need that overhead at some point.

I’ve seen some folks run 2400-2500 psi to help injectors that are too small get more flow, but you’ll sacrifice some flow from the HPFP. Trade off I guess.

[Joshinator99]

Originally Posted by shinysun

Is it Ok to use 2900PSI with LPE big bore? The homepage is saying "Never exceed 15 Mpa", 2150psi.

Originally Posted by Chrome383Z

The LT1 pump is rated for 2175 I believe and the LPE is based on it. I’m not exactly sure what all they do but I believe it’s bored out and maybe machined deeper for increased stroke. Folks on here have ran them at higher pressures and I haven’t read of any failures but always a chance of pushing things closer to that edge.

However I haven’t seen anyone get good results cranking the pressure up, flow drops off. The LPE pump flows 10% more at 2150psi then the LT4 at 2900psi. So ideally you’ll want to run at the rated pressure.

Just have to make sure you have enough injector at the lower pressure if that makes sense. Example an LT4 injector at 2900 psi may flow similar to a +30 at 2150 psi. That’s why I bought +30 with my LPE pump. Figure I’m going to need that overhead at some point.

I’ve seen some folks run 2400-2500 psi to help injectors that are too small get more flow, but you’ll sacrifice some flow from the HPFP. Trade off I guess.

Well said.

You really need +30 injectors at a minimum, and preferably +52/+65 injectors to take full advantage of the LPE BB HPFP.

[KingLT1]

Originally Posted by shinysun

Is it Ok to use 2900PSI with LPE big bore? The homepage is saying "Never exceed 15 Mpa", 2150psi.

I have ran mine @ 2900psi for years with LT4 injectors with no issues. When I moved to XDI +30's I dropped back to 2175psi(LT1) to take strain off the HPFP and Low side. We also ran the C7Z at the same psi until installing the +65's.

So it comes down to what parts are being used.

LT4 injectors are based around 2900psi. So the LPE hpfp really needs turned up for them. Not sure how they would act with less pressure but my guess is it would be a waste of time. You really need larger injectors to run lower psi.

FIC +30 gen 1's will run @ 2900 psi. The gen 2's will misfire. At least that has been my experience.

XDI +30's will handle 2900 psi. I ran them @ both LT1 and LT4 pressures with no issues.

XDI +65's want no more then 2600 psi based on the spec sheet. Not sure if they will handle more psi without misfiring or not.

[ZO6Ted]

King my other vehicle has an LT1 pump and L83 injectors. I bought LT4 inj early on before I started getting schooled here. So would it basically be a waste of time to install the LT4 inj without the LT4 pump or BB? Also for a lessor hp would Lt1 inj be a work around to keep my pump and skip the LT4's?

[KingLT1]

Originally Posted by ZO6Ted

King my other vehicle has an LT1 pump and L83 injectors. I bought LT4 inj early on before I started getting schooled here. So would it basically be a waste of time to install the LT4 inj without the LT4 pump or BB? Also for a lessor hp would Lt1 inj be a work around to keep my pump and skip the LT4's?

I think the LT4's would still be a upgrade even at lower pressure since they are significantly larger then L83 injectors.

[ZO6Ted]

Thanks King and maybe if I did do the BB I would clear my Whipple manifold without grinding since it's based on an LT1 pump? No reply needed if that's correct sir. Many thanks!

[Dennis 2ss]

Originally Posted by KingLT1

I think the LT4's would still be a upgrade even at lower pressure since they are significantly larger then L83 injectors.

Hey King I’m going with this on my boosted LT1

LT4 intank plus booster
32% cam
LT4 hpfp
Fic 30s

How will this do? Should I go with the LPE pump instead and dsx aux also?
Goal would be going e65.

[KingLT1]

Originally Posted by Dennis 2ss

Hey King I’m going with this on my boosted LT1

LT4 intank plus booster
32% cam
LT4 hpfp
Fic 30s

How will this do? Should I go with the LPE pump instead and dsx aux also?
Goal would be going e65.

Depends on boost level and power it's trying to make. My guess is that setup should handle E65 up to 750-760whp before the low side starts to reach it's limits.

Side note: The gen 2 FIC +30's we used would not run LT4 rail pressure without misfiring. The gen 1's would however. You need 2900 psi for the LT4 hpfp.

I would do:

XDI +30
LPE HPFP pump
+42% cam lobe

This will allow you to run less rail pressure(2175psi), have plenty of fuel for E65, and the low side will extend out a bit further and you might not need any additional low side upgrades aside from the LT4/JMS combo up to 13-14psi of boost.

[Dennis 2ss]

Originally Posted by KingLT1

Depends on boost level and power it's trying to make. My guess is that setup should handle E65 up to 750-760whp before the low side starts to reach it's limits.

Side note: The gen 2 FIC +30's we used would not run LT4 rail pressure without misfiring. The gen 1's would however. You need 2900 psi for the LT4 hpfp.

I would do:

XDI +30
LPE HPFP pump
+42% cam lobe

This will allow you to run less rail pressure(2175psi), have plenty of fuel for E65, and the low side will extend out a bit further and you might not need any additional low side upgrades aside from the LT4/JMS combo up to 13-14psi of boost.

Ok im going to be honest and already got the 32% cam and FIC 30s. Had no idea about the missfire and thought the FICs was the better option. But will getting the LPE hpfp Pump at least help lower the railpressure then? Thanks for the info.

[KingLT1]

Yeah we didn't neither. First set of FIC worked fine at 2900psi. The second set no bueno. Yes the LPE hpfp is designed around lower pressure so it will work. We recently installed a similar high side setup on a ZL1.

FIC +30
LPE HPFP
JMS booster

Runs E60 @ 13.5psi of boost with headroom to spare.

[Dennis 2ss]

Originally Posted by KingLT1

Yeah we didn't neither. First set of FIC worked fine at 2900psi. The second set no bueno. Yes the LPE hpfp is designed around lower pressure so it will work. We recently installed a similar high side setup on a ZL1.

FIC +30
LPE HPFP
JMS booster

Runs E60 @ 13.5psi of boost with headroom to spare.

Ok thanks again for the info! I’ll order myself a lpe pump now!