Limits on LT4 in tank pump when highside is upgraded?

[Saberscar223]

Ive done a ton of researching and I cant seem to find out what the limits of the lt4 lowside is. Im planning to get the Katech HPFP and LT4 injectors and already have a cam. but Im hoping to just run a BAP on the LT4 in tank system. It seems people default to doing the whole fuel system or using an AUX for the lowside but I cant seem to find anyone who took the LT4 lowside to its limits when highside is upgraded. I'm hoping to run ~E70 at ~700WHP with ~7psi.

[TriPinTaZ]

Depends on what year/model. The LT4 low side was upgraded in 2019 when the ZR1 came out. The ZR1 and Z06 got the better low side. It eventually made it into the Camaro and CTS-v 1LE cars and LT4's but there isn't a specific model year. I have seen that pretty much any 2022+ Camaro ZL1 or 1LE low side performs better.

Anyhow, that said, the LT4 low side with the JMS , from the older cars can handle ~700 wheel on E50 blend and the newer LT4 pump can handle up to ~750 wheel on E50 blend before you start seeing the pressure not keep up with commanded. This is a ballpark and your mileage may vary based on E % and target lambda. The JMS will support XDI 30's and the Goliath or the LT4 hpfp with a cam, but not to the max they are capable of delivering. You will be limited by the low side unless you go with a better solution. Most people that go with those mods are trying to surpass ~700 wheel.

[2018CamaroSS1LE]

Timely post. I have a Camaro SS 1LE. Added the LT4 blower/LT4 injectors/HPFP and 416 with mild cam. I'm at 740 CHP and the low side was inconsistent (French made dyno so wheel power is not equivalent). My tuner said I need the JMS, but I don't plan any further upgrades. I'm just concerned if the combination is safe for sustained autobahn runs...I really don't want to add the JMS - more parts to fail.

Sounds like I could just buy a later model OEM lowside fuel pump...thanks!

[Saberscar223]

Depends on what year/model. The LT4 low side was upgraded in 2019 when the ZR1 came out. The ZR1 and Z06 got the better low side. It eventually made it into the Camaro and CTS-v 1LE cars and LT4's but there isn't a specific model year. I have seen that pretty much any 2022+ Camaro ZL1 or 1LE low side performs better.

Anyhow, that said, the LT4 low side with the JMS , from the older cars can handle ~700 wheel on E50 blend and the newer LT4 pump can handle up to ~750 wheel on E50 blend before you start seeing the pressure not keep up with commanded. This is a ballpark and your mileage may vary based on E % and target lambda. The JMS will support XDI 30's and the Goliath or the LT4 hpfp with a cam, but not to the max they are capable of delivering. You will be limited by the low side unless you go with a better solution. Most people that go with those mods are trying to surpass ~700 wheel.

Yeah I have a 2023 2SS, I heard that all the fuel pumps are the same for LT1s and LT4s 2020 and up even non 1les. At least they appear to have the same part numbers. Also Im keeping stock internals so ~700whp is where Im trying to stay at.

[Saberscar223]

Timely post. I have a Camaro SS 1LE. Added the LT4 blower/LT4 injectors/HPFP and 416 with mild cam. I'm at 740 CHP and the low side was inconsistent (French made dyno so wheel power is not equivalent). My tuner said I need the JMS, but I don't plan any further upgrades. I'm just concerned if the combination is safe for sustained autobahn runs...I really don't want to add the JMS - more parts to fail.

Sounds like I could just buy a later model OEM lowside fuel pump...thanks!

What %E and boost level are you running in this build?

[2018CamaroSS1LE]

Saberscar223: German fuel is 5% ethanol and the stock pulleys at 7100 rpm hit 11.5 psi (Kong X port).