[jessrayo]

In my opinion, now that the systems are available. You should just plan to add a port injection system and leave the direct injection system stock. Do this and no more fuel worries.

[JROC]

Originally Posted by KingLT1

If you plan on making big power down the road, I would probably just pony up and get the new Weapon X SPI system.

https://weaponxmotorsports.com/produ...-cts-v-lt1-lt4

TTT.

I'm bumping this thread to ask a few questions about the system/systems that add port injection to the fuel system.

- Do these systems cure any carbon buildup issues on the intake valves that is common with DI fuel systems? Also isn't the DI responsible for the exhaust tips blackening so quick after cleaning them? Would these systems help slow that?

- Is there a big change in fuel economy when not loading the motor with this added fuel system?

- How reliable are they? If you lose a fuel pump (either the DO or PI pump) is there a way to tune or retard the car not to let it make more than X power to help save the motor? One issue dual pumps can cause is if one goes out you may not know it and you can starve your car of fuel when you get on the throttle.

- Does the system allow for big power when used along side the stock DI system, or should you upgrade it as well seeing as how these modern DI cars allow for higher compression and boost levels than traditional PI systems could support on pump gas?

Thanks,

Jesse

[oldman]

I sat on the fence for a long time on this. I went DI, I have cleaned my intake valves twice with nylon brush and intake valve cleaner, it took my 3 hours and the valves / port look almost new...
I went DI because at the end of the day, it is 100% factory dependable. Now that I'm retired, the dual inject would let me play with combos a little bit more, I'm an OK tuner so for my final tunes I've only used professional tuners. So I think it comes down to do you want to tune it yourself and for me a secondary system would allow me to a little simple tweaking to fuel curve.

[KingLT1]

Originally Posted by JROC

TTT.

I'm bumping this thread to ask a few questions about the system/systems that add port injection to the fuel system.

- Do these systems cure any carbon buildup issues on the intake valves that is common with DI fuel systems? Also isn't the DI responsible for the exhaust tips blackening so quick after cleaning them? Would these systems help slow that?

- Is there a big change in fuel economy when not loading the motor with this added fuel system?

- How reliable are they? If you lose a fuel pump (either the DO or PI pump) is there a way to tune or retard the car not to let it make more than X power to help save the motor? One issue dual pumps can cause is if one goes out you may not know it and you can starve your car of fuel when you get on the throttle.

- Does the system allow for big power when used along side the stock DI system, or should you upgrade it as well seeing as how these modern DI cars allow for higher compression and boost levels than traditional PI systems could support on pump gas?

Thanks,

Jesse

Look up Ted Jenetty's latest 2650 ZL1 build. 1100whp with the XDI sytem on E80. No port injection, no meth. Things have changed a little since I made that post. DI can make big power. The XDI setups belt driven secondary HPFP and +60 injectors will support plenty of fuel. Of course it's not cheap nor is SPI.

However to answer your question, yes the SPI systems work along side the DI just like the factory LT5. It activates at a set point(perhaps off MAP kpa?) then supplies the additional fuel. Crawford racing makes a setup that has gained some popularity. I am not sure how reliable it is, not many reporting much about it. It will support big power without needing to upgrade any of the factory DI fueling from what I have seen. I wouldn't see there being any difference in economy since it only activates when needed.

At the end of the day, a Direct Port meth system from Pro Meth with a full LT4 DI fuel system is probably the most cost effective way to support 1000+whp. Anything that sprays fuel or meth down the intake runner similar to Port Injection will help clean the back side of the valves. So Meth or SPI setup would help in that regard.

[JROC]

Originally Posted by KingLT1

Look up Ted Jenetty's latest 2650 ZL1 build. 1100whp with the XDI sytem on E80. No port injection, no meth. Things have changed a little since I made that post. DI can make big power. The XDI setups belt driven secondary HPFP and +60 injectors will support plenty of fuel. Of course it's not cheap nor is SPI.

However to answer your question, yes the SPI systems work along side the DI just like the factory LT5. It activates at a set point(perhaps off MAP kpa?) then supplies the additional fuel. Crawford racing makes a setup that has gained some popularity. I am not sure how reliable it is, not many reporting much about it. It will support big power without needing to upgrade any of the factory DI fueling from what I have seen. I wouldn't see there being any difference in economy since it only activates when needed.

At the end of the day, a Direct Port meth system from Pro Meth with a full LT4 DI fuel system is probably the most cost effective way to support 1000+whp. Anything that sprays fuel or meth down the intake runner similar to Port Injection will help clean the back side of the valves. So Meth or SPI setup would help in that regard.

Okay thanks.

So upgrading the injectors is all that's needed to support say 800+ with E85?
https://www.xtreme-di.com/product/xd...uel-injectors/

I'm guessing there sight is talking about using them with the SLE/ZL1 pump? Do you know how well one of those boost-a-pumps works with these cars? How much power do you think a boost-a-pump and some OEM LT4 injectors will support on just 93 octane? I know all cars are going to be a little different. (for example my old Terminator supported 500 WHP without maxing out the stock 39 lb injectors, but many people needed to go to some 60's at that point) If you were to do say a stock bottomend, H/C/I/bolton/tune build what kind of upgrades (fuel and otherwise) would you want to take to help minimize reliability issues? I'm guessing other than fueling it you would need to upgrade you valve springs, pushrods, lifters, oil pump? From my understanding the pistons are the weak link in the bottomend?

I've always thought of meth injection kind of like I do N2O. I know it's affective and works for intended purpose, but it's just never been something I was interested in doing to my DD car.

Sorry for bombarding you with questions.

[JROC]

Originally Posted by oldman

I sat on the fence for a long time on this. I went DI, I have cleaned my intake valves twice with nylon brush and intake valve cleaner, it took my 3 hours and the valves / port look almost new...
I went DI because at the end of the day, it is 100% factory dependable. Now that I'm retired, the dual inject would let me play with combos a little bit more, I'm an OK tuner so for my final tunes I've only used professional tuners. So I think it comes down to do you want to tune it yourself and for me a secondary system would allow me to a little simple tweaking to fuel curve.

To clean your valves are you just taking off the intake and scrubbing them thru the ports? I'm guessing that since you take the time to do it then it's pretty affective? How often should you do this, and if anything used and the carbon gets in the cylinders I'm assuming that it will just burn off in the motor?

[JANNETTYRACING]

Originally Posted by JROC

Okay thanks.

So upgrading the injectors is all that's needed to support say 800+ with E85?
https://www.xtreme-di.com/product/xd...uel-injectors/

I'm guessing there sight is talking about using them with the SLE/ZL1 pump? Do you know how well one of those boost-a-pumps works with these cars? How much power do you think a boost-a-pump and some OEM LT4 injectors will support on just 93 octane? I know all cars are going to be a little different. (for example my old Terminator supported 500 WHP without maxing out the stock 39 lb injectors, but many people needed to go to some 60's at that point) If you were to do say a stock bottomend, H/C/I/bolton/tune build what kind of upgrades (fuel and otherwise) would you want to take to help minimize reliability issues? I'm guessing other than fueling it you would need to upgrade you valve springs, pushrods, lifters, oil pump? From my understanding the pistons are the weak link in the bottomend?

I've always thought of meth injection kind of like I do N2O. I know it's affective and works for intended purpose, but it's just never been something I was interested in doing to my DD car.

Sorry for bombarding you with questions.

A complete LT4 fuel system with JMS voltage booster will support 750 RWHP on Gasoline Preferably race gas.

Add the JRE Terminator cam and the system will support 850 RWHP on Gasoline Preferably race gas.

Ted.

I guess the short answer is NO.

[KingLT1]

Originally Posted by JROC

Okay thanks.

So upgrading the injectors is all that's needed to support say 800+ with E85?
https://www.xtreme-di.com/product/xd...uel-injectors/

I'm guessing there sight is talking about using them with the SLE/ZL1 pump? Do you know how well one of those boost-a-pumps works with these cars? How much power do you think a boost-a-pump and some OEM LT4 injectors will support on just 93 octane? I know all cars are going to be a little different. (for example my old Terminator supported 500 WHP without maxing out the stock 39 lb injectors, but many people needed to go to some 60's at that point) If you were to do say a stock bottomend, H/C/I/bolton/tune build what kind of upgrades (fuel and otherwise) would you want to take to help minimize reliability issues? I'm guessing other than fueling it you would need to upgrade you valve springs, pushrods, lifters, oil pump? From my understanding the pistons are the weak link in the bottomend?

I've always thought of meth injection kind of like I do N2O. I know it's affective and works for intended purpose, but it's just never been something I was interested in doing to my DD car.

Sorry for bombarding you with questions.

If you did +30 injectors, LPE big bore, and a DSX aux pump you could probably make 800's on E85 with a cam. The LT4 in-tank with JMS might handle that as well. Once you price that out, it isn't much if any cheaper then a SPI system. However if you are willing to mix the E content down to around 60% it frees up a ton of headroom. Either way you still need a cam to drive the DI pump unless you go to a secondary system.

The JMS voltage booster works great. It isn't the same as voltage boosting older fuel systems. Our cars have a fuel system control module(FSCM) which the pump is Pulse width modulated. So the JMS only applies voltage to the control module on demand. The control module increases the pulse widths to the pump to increase fuel delivery. These systems are designed to handle different loads being you can adjust the fuel pump output in the tune. The problem is these cars are variable charging, so unless you change the system to sustain a specific voltage at all times which means the alternator is always on, then you get voltage fluctuation in the system which effects the fuel pumps output. The JMS is there to ensure consistent voltage is applied to the FSCM. So the pump will deliver consistent fuel pressure at all times without needing to alter how the charging system works.

The highest numbers I have seen on a stone stock LT1 engine was Dan Hackers P1x setup. LT4 fueling, Aux low side, meth, msd intake, headers, 12 psi. Made like 760whp on 93 and meth.

Again, I think you could do the same thing with a SPI or XDI system on E, but I wouldn't run any more then 12 psi on stock piston's. I would probably keep boost around 10-11psi depending on the use of the car. I don't think these engines will make 800+ on a stock cam @ 12 psi. You would likely need 14+ and I doubt the stock rings will tolerate that for very long. So it's kind of walking a tight rope with the LT1. You really need cam and heads so you can run less boost to keep the rings happier in order to reach that 800 number. At that point the engine likely comes out and you upgrade the rods/pistons and do a full build anyway which is the common path most take.

Moral of the story, without Meth, going above 700whp on Stock cam engine creates a lot more cost and complexity to the setup in order to make more power reliably.

[oldman]

Originally Posted by JROC

To clean your valves are you just taking off the intake and scrubbing them thru the ports? I'm guessing that since you take the time to do it then it's pretty affective? How often should you do this, and if anything used and the carbon gets in the cylinders I'm assuming that it will just burn off in the motor?

I take the intake off. The intake valve is close so not much gets into the engine. I put some paper towels in and use air.