[KingLT1]

Originally Posted by tom's2005gto

How does the boosted LT4 handle fuel pressure and voltage drops? Does the ZL1 utilize a voltage booster for the LT4 in tank pump? If not, why can't we just install the LT4 pump / bucket kit? I'm sure I'm missing something, but that's why I'm asking, because I don't understand.

The LT4 engine has enough fuel system headroom that the voltage fluctuation isn't going to cause any issues. I am betting the OEM spec'd the system to operate fine at 12.5 volts. The LT1 on the other hand was not built with the intentions of being boosted. Just a base supercharger kit puts the stock fuel system close to it's limits. When you start modding and closing in on the fuel systems limits, there is less room for error so to speak. so making sure the pump is operating at a consistent voltage becomes much more important.

on 93, you might be fine with just a ZL1 pump...ideally you should run both. I am and my low side is holding rock steady @ 8psi on E80.

[tom's2005gto]

^^^^ thanks for clarification. I have an auxiliary pump kit yet to install with the rest of the mods (Vortech kit and more) Just was debating aux kit vs. LT4 bucket and/or voltage booster.

[KingLT1]

Originally Posted by tom's2005gto

^^^^ thanks for clarification. I have an auxiliary pump kit yet to install with the rest of the mods (Vortech kit and more) Just was debating aux kit vs. LT4 bucket and/or voltage booster.

The Auxiliary pump is a easier install, should offer more headroom, and not much more money. I also don't think you would need a JMS unit with it. I just wanted a more OEM solution and The ZL1 in-tank/JMS combo has shown to handle cars making 760whp on E85 without much issue. The aux setup has been proven to handle 900+ on E85. I guess it all depends on your end goal and if a few hours of extra work is worth it to you.

[parish8]

Originally Posted by Red Lightening

I purchased the JMS booster in process of having the full Lt4 fuel system installed by my tuner. He does not recommend the use the JMS booster based on my current and future applications, (650-700 whp) as the GenV Lt1 computer compensates for voltage irregularities and is more than capable of supporting the fuel requirements I am currently in need of as well as future requirements at 650-700 whp. His concern is that with consistent voltage from the JMS Booster, there is consistent fuel, thus increasing the return fuel on lower rpms with the result of increased fuel temperatures in the tank. He said it can be done, just not what he would recommend. I certainly am not an expert and I know there are numerous opinions, but I would talk with your tuner first. Prior to the fuel upgrade I currently have Kooks 1 7/8 LT's, (w/high flow cats-coming off and don't recommend as they are reported to be "melting down" on similar applications), Snow meth kit, (specifically for cooling-starts at 3lbs and 100% at 6lbs only using the setting of 18 out of 50, conservative, btw all stainless lines), AWE touring exhaust, (very loud 0-drone) I am at 602whp/555wt. The Lt4 upgrade is to run E85. I know this is overkill on some info, just wish I would have had some of it prior to some of my purchases

Your tuner is confused. Much of what he said might apply to an older car.

We have no return fuel. The pump is pulse width modulated to control flow and is closed loop, more voltage will not increase minimum flow. The factory computer allows voltage to be inconsistent. Lower voltage will reduce maximum pump flow. To keep flow(and voltage) consistent lots of people use a jms

[BlueCamaro6]

Originally Posted by tom's2005gto

How does the boosted LT4 handle fuel pressure and voltage drops? Does the ZL1 utilize a voltage booster for the LT4 in tank pump? If not, why can't we just install the LT4 pump / bucket kit? I'm sure I'm missing something, but that's why I'm asking, because I don't understand.

Exactly..That's why I tune the fscm and calibrate parameters within the ecm to hold steady pressure at the in-tank pump. I do have the LT4 fuel system, but others have had pressure drops and purchased other items to compensate.
I've run boost up to 12psi and still had 64psi lowside, 2,941psi high side, 15.2V, @6,300 and will do this all day long to 6,700 - (photo was in my phone)

I could watch my fuel rail pressure jump around as it climbed with factory settings, but not after calibrating the injection timing. Very smooth gauge on logs after that and car felt much better. I was surprised SOI adjustment made such a difference.