[Wv1lecamaro]

Hi guys I’m doing a lt4 kit from weapon x I have a 18 1le I know I have the Zl1 in tank pump if I do high side and injectors can I run e85 or will it still not be enough?running stock manifolds no headers and a axle back is all on the exhaust part thanks for your help

[KingLT1]

Depends on boost level. 5-6psi will allow whatever E is at your pump(Normally E75 on average). 7-8psi will need mixed down to E50-E60. 9-10psi E40-E50. Boost changes with temperature. so either lower boost by moving up to a larger pulley in the cooler months or reduce E content. I normally just reduce E content because you don't need as much octane with cooler denser air and anything above E40 is plenty of octane for most builds anyway.

[Katech_Zach]

You will not be able to run full e85.

[L78toLT1]

Originally Posted by KingLT1

Depends on boost level. 5-6psi will allow whatever E is at your pump(Normally E75 on average). 7-8psi will need mixed down to E50-E60. 9-10psi E40-E50. Boost changes with temperature. so either lower boost by moving up to a larger pulley in the cooler months or reduce E content. I normally just reduce E content because you don't need as much octane with cooler denser air and anything above E40 is plenty of octane for most builds anyway.

King, what are your thoughts on the balance of E head room provided by a 32% or larger fuel lobe vs the additional fuel demand resulting from the larger cam, assuming a similar level of boost? Obviously, the cam specs will also need to be considered. For talking purposes, assume a .635/.635, 228/218 bumpstick.

[KingLT1]

Originally Posted by L78toLT1

King, what are your thoughts on the balance of E head room provided by a 32% or larger fuel lobe vs the additional fuel demand resulting from the larger cam, assuming a similar level of boost? Obviously, the cam specs will also need to be considered. For talking purposes, assume a .635/.635, 228/218 bumpstick.

For starters(and this might be a typo) but a reverse split cam is absolutely the wrong cam for these engines...especially supercharged. These LT engines like a healthy split about 10/12 degrees biased towards the exhaust side.

Aside from that the cam specs are not going to play much of a role compared to the fuel lobe. You are 10-15whp difference at best between a stage 1 and stage 2 supercharger cam. Not enough to heavily impact fueling.

32% lobe paired with the LT4 fuel system should be good for E50-E60 or so up to 14psi and roughly mid 700whp would be my guess.

If you want to run E in the 800whp+ range(15+ psi) then ideally you need a +30 injectors, LPE DI pump, 38-42% fuel lobe on the cam. The 32% was designed around the LT4 pump and if you run that with the LPE pump then you limit it's capabilities. That's why the LPE pump hasn't been super popular because most do not know how to utilize it properly. It's designed around volume and it likes to be driven by a bigger fuel lobe then the LT4. That is why LPE recommends the 7.85mm lobe(42%) GT35 cam, big bore pump, and +52% injectors.

Now here is the thing with injectors and pumps. The LPE big bore seems to be stable up to 2900psi. So if you run the +30 injectors and LPE BB pump @ 2900psi, the results are likely going to be similar to the LPE +52 and LPE BB pump at 2175psi. The LPE injectors won't work correctly above 22or 2400psi. I haven't tested this in person so I am just passing along info I was told. Take this paragraph fwiw.

What I have tested is +30 FIC injectors, LPE BB, 32% lobe, 2900psi commanded, Cordes low side, and it will feed a built 11:1 LT4 HC 2650 @ 16psi on E50-60 max. If it had a larger fuel lobe then it could run more E. High side is dropping off.

Hope this answers your question!

[Joshinator99]

Originally Posted by KingLT1

For starters(and this might be a typo) but a reverse split cam is absolutely the wrong cam for these engines...especially supercharged. These LT engines like a healthy split about 10/12 degrees biased towards the exhaust side.

Aside from that the cam specs are not going to play much of a role compared to the fuel lobe. You are 10-15whp difference at best between a stage 1 and stage 2 supercharger cam. Not enough to heavily impact fueling.

32% lobe paired with the LT4 fuel system should be good for E50-E60 or so up to 14psi and roughly mid 700whp would be my guess.

If you want to run E in the 800whp+ range(15+ psi) then ideally you need a +30 injectors, LPE DI pump, 38-42% fuel lobe on the cam. The 32% was designed around the LT4 pump and if you run that with the LPE pump then you limit it's capabilities. That's why the LPE pump hasn't been super popular because most do not know how to utilize it properly. It's designed around volume and it likes to be driven by a bigger fuel lobe then the LT4. That is why LPE recommends the 7.85mm lobe(42%) GT35 cam, big bore pump, and +52% injectors.

Now here is the thing with injectors and pumps. The LPE big bore seems to be stable up to 2900psi. So if you run the +30 injectors and LPE BB pump @ 2900psi, the results are likely going to be similar to the LPE +52 and LPE BB pump at 2175psi. The LPE injectors won't work correctly above 22or 2400psi. I haven't tested this in person so I am just passing along info I was told. Take this paragraph fwiw.

What I have tested is +30 FIC injectors, LPE BB, 32% lobe, 2900psi commanded, Cordes low side, and it will feed a built 11:1 LT4 HC 2650 @ 16psi on E50-60 max. If it had a larger fuel lobe then it could run more E. High side is dropping off.

Hope this answers your question!

King, you're spot on about the +32 fuel lobe not being enough. It definitely limits the output of the LPE BB HPFP.

I've run the LPE +52% injectors at 2500 PSI and did not have any issue, and the max you can run is 2900 PSI according to the instructions shipped with mine. But, the BB HPFP could not keep up as I turned up the E content. So while raising the HPFP pressure band aids a +30 injector, but when you raise a pump's pressure you lose volume. At the end of the day that is the big issue once you have big injectors. So in my humble opinion you can make more power with +52/+65 injectors at 2175 psi than you can with +30 injectors at 2900, because the BB HPFP will run out of steam sooner at 2900 psi than it will at 2175 psi. And raising a pump pressure 30% does not equate to 30% more flow through a fixed orifice, so while you can gain some headroom for sure, you're better off at lower pressure so the pump can move more volume. Hope that makes sense.. LOL

[KingLT1]

Yes it does but what I have noticed is going from 2175psi to 2900psi lowered injector pulses almost a full point. So the difference is substantial if the high side pump can keep up. There has to be a reason why GM chose higher pressure with the LT4 imo.

[Joshinator99]

Originally Posted by KingLT1

Yes it does but what I have noticed is going from 2175psi to 2900psi lowered injector pulses almost a full point. So the difference is substantial if the high side pump can keep up. There has to be a reason why GM chose higher pressure with the LT4 imo.

Agreed, I guess we need some more cars like mine and your brothers so that we can figure this out!

But TLDR, definitely want the biggest cam fuel lobe you can get! I'm finding that out the hard way... like everything else...lol

[KingLT1]

Originally Posted by Joshinator99

Agreed, I guess we need some more cars like mine and your brothers so that we can figure this out!

But TLDR, definitely want the biggest cam fuel lobe you can get! I'm finding that out the hard way... like everything else...lol

Exactly...we have run into the same thing. The problem is the cost to go XDI +60's and change cams. spend another 6-8k for 20whp gain on Full E85 vs E50 and the convenience of not needing to mix?

At that point I would be tempted to try out the ToohighPsi port injection plates. The setup costs 2k and that gets you the plates, injectors, controller and harness. They now have plates that work with the Whipple. I am only hesitant because of the MAF fusion controller. Can not find info on how to set it up and integrate. If they provide some tuning support then it could be a good solution.

[Wv1lecamaro]

Thanks guys been on phone with adm super good guy he told me with lt4 fueling and running a 2.75 pulley I can run full e85 with no prob ordered his kit today and have the blower already appreciate everybody’s feedback

[CamOnlyJabroni]

Originally Posted by Joshinator99

Agreed, I guess we need some more cars like mine and your brothers so that we can figure this out!

But TLDR, definitely want the biggest cam fuel lobe you can get! I'm finding that out the hard way... like everything else...lol

FWIW I’m running a 8.4 lower and a 3.14 upper blower rpm wise.

[Evansa22]

Originally Posted by KingLT1

Exactly...we have run into the same thing. The problem is the cost to go XDI +60's and change cams. spend another 6-8k for 20whp gain on Full E85 vs E50 and the convenience of not needing to mix?

At that point I would be tempted to try out the ToohighPsi port injection plates. The setup costs 2k and that gets you the plates, injectors, controller and harness. They now have plates that work with the Whipple. I am only hesitant because of the MAF fusion controller. Can not find info on how to set it up and integrate. If they provide some tuning support then it could be a good solution.

Definitely been looking in to the wep x spi kit. More expensive but should have all the fuel headroom. Wondering if its a better option than changing out the stock cam and still being limited fuel wise?

[KingLT1]

If you are planning on running E85 yes. The gains from E85 are similar to a cam swap on 93 octane. So as long as you have enough fuel system the sky is the limit. Your next hurdle will be supercharger limitation. The stock blower would work better with a cam so you don't have to spin the blower harder to make more power. 2650 swap with SPI kit should make around 780-800whp on E85 @ 16-17psi with a otherwise stock LT4. I am guessing the costs between a H/C stock blower build on 93 would be similar to a 2650/spi setup on E85?

[Evansa22]

Right on, heads/cam is a little cheaper than going maggi/spi. Right now I'm probably around 660 whp, 730-750 would make me happy. Think the blower/port kit would just put me at too much power, which im pretty sure no one on here has ever said haha. Road course setup car so not shooting for the moon. Thanks