RoxyCarter

Kingtalon...

We aren't modifying the DI high pressure pump.

we are modifying the low side pump... which has existed in its current configuration, since the C5.

in the c7, the high side pump was added. Now the low side pump is just a fuel mover... If the high side pump and injectors do not pump.. the car does not get fuel. Doesnt matter if we make 150psi on the low side... high side still calls the shots.

Low side moves fuel up to the high side pump. The high side pump can outrun the low side in tank pump, in their stock configurations and stock low side voltage.

the in tank pump is the weak link at max throttle.

61psi in low side line, is still ample fuel. The car is not lean yet.

to set a threshold at 61psi on the low side line... and put the car into limp mode at anything below 61, has zero risk.

I'm not going to back down on this.

It may all be a mystery to you, but it is not to some of us who understand it well.

you are literally scaring people away from experimenting with the system, making it sound like they will be messing with their DI fuel system.

not the case. 71 expected pressure, 61 min pressure.

its not complicated.

current stock system and computer tries to maintain 71psi.

car goes into boost, in stock config, and it's probably 68psi in the line at wot on a warm day, as the computer commands the low side pump to max duty.

It might get around 60psi when its cold out and at sea level while at max duty since the high side is ordered to pump more when more incoming o2 is detected. Either way... the stock low side in tank pump, at 13.7 volts... does not stay above 61psi when the high side starts really engaging.

In stock configuration, the high side can pump more fuel faster than the low side can. Fact.

giving the low side pump, extra voltage, so when the computer tells it to pump at max capacity, it's max is able to keep the feed line closer to 71psi instead of 60psi, is not a big deal.

the high side pump just needs fed. If the feed line goes below 61, the car shuts down. This is not a knock sensor. This is not rocket science either. It is simple and it is safe. And it works without flaw.

are there bugs to be worked out on the booster? Sure, maybe. But making it sound like people are going to ruin their high side fuel systems, when all you might actually do is mess up your stock in tank pump.. and take it to the dealer after and have it fixed under warranty... for free... is not drama.

At least not the drama you are trying to make it out to be.

ironically, it's the least dramatic option of them all.

fore multiple in tank pumps, if one pump fails or there is any trouble, you'd have to remove those yourself, dealer won't touch that. You have to drop the drivers tank, twice. Once in, once to get them back out after the failure. It's a job.

added external pump that taps into the tank, dealers won't touch that. Now you have a hole in your tank forever, even if you plug it. Goodbye warranty.

meth injection... more money for that kit and aftermarket tune usually required, right? So a lot more money, and No more warranty. If you have trouble, dealer won't touch it.

Meanwhile, if this voltage booster ruins the stock pump... a person could take the voltage booster off and have the car fixed under warranty, as it leaves no trace it was ever on the car. Stock tune. Easy to test.

all it takes is one or 2 people to test it and see if it works, troubleshoot it's small compatibility hickups which we are here to help with, and then we all learn. If it's not compatible and can't be solved, then we all learn that it is a dead end.

but we need people willing to try it instead of talk everyone out of it.

and instead... you are telling everyone is the most spooky thing ever... when its the least drama of the 3 options to reverse if there is an issue

That will be the last i want to defend atljar and my position on this. If you want to keep countering us, so be it, but I think you are only demonstrating you have over analyzed the situation, to the point of giving bad advice, to those who are willing to test it out

Kingtal0n

I helped a friend setup a DI system in an old car recently.
Here is an email from aeromotive regarding the DI system when I was looking for a suitable pump/applicationAeromotive says:
"Duplicating the OEM fuel system for GM DI engines, but in an early muscle car or truck, is extremely difficult at best and would frankly only be successfully accomplished by transplanting the complete tank and EEC (evaporative emission control) systems from the host vehicle.
In reality it’s not at all necessary as the DI pump simply needs a proper supply of fuel at a modest, stable pressure to actually function perfectly.If you want to run the factory, pulse modulated, EPA fuel system you'll need to rob a fuel pump module from a late model corvette and figure out how to set it all in a tank that will fit your car.Honestly, you do not have to go to that extent to properly fuel a GM DI engine.

The factory Corvette fuel system is incredibly complex due to a combination of issues related to the car having two tanks and the EPA evaporative emissions standards which have forced the OEM into a complex "returnless" fuel system. Although you're welcome to try and duplicate this system, I can tell you that the only way it will work in the end is if you transplant everything from the factory Corvette fuel system into your car. If you've ever seen the Corvette fuel tanks you know how utterly impractical that is.Without getting too far into the technical weeds, the good news is that the DI engine itself needs a very simple fuel system to feed the injection pump.

After hundreds of hours of dyno testing by a handful of the top aftermarket performance tuners of GM engines, who were obviously looking for anything that would make more power, the bottom line (and disappointing for them) is that if the fuel system can maintain a minimum 55-PSI to the inlet of the injection pump the engine produces identical FWHP compared to any higher pressure tested, up to 100- PSI.

The problem for the end user isn't creating a fuel system that can do that simple job, the real problem is the ECU's expectation that it will be controlling a fuel pump with pulse modulation, and varying pressure in the system to account for potential issues related to the factory system being dead-head (returnless) for the length of the car. If you create a simple fuel system with pump in the tank, filter, fuel pressure regulator located at the engine with vacuum/boost reference, you can set the base pressure at 58 PSI and vacuum will pull pressure down, boost will raise it up, and the injection pump will be perfectly happy and do the job flawlessly.

What you'll need to do if you go this route is find someone with a tuner/program you can install that will shut the pump driver off and ignore the fuel pressure sensor to keep from setting a check engine light. The wire in the harness that turns the drive module on will also work to turn the relay on that runs the pump and continuous voltage. SCT, EFI Live, HP Tuners, should all be good candidates.

The fuel system I'd put in the car would be P/N 17166, which several dozen builders with LT1 and LT4's have used, and it has pretty much everything you need except fuel lines and hose ends in the box. It will connect directly to the inlet of the injection pump just like it does to the inlet of a return less fuel rail.https://www.aeromotiveinc.com/produc...tallation-kit/We have a higher flow Phantom system that has proven ideal for supplying an LT4 that is making higher the stock HP. I've attached a diagram that will lay this out for you as an option. The Phantom Flex is P/N 18310, and you'll need a 16307 wiring kit and a 15632 gauge, everything else is listed in the diagram. Note, the diagram shows a fuel rail, I know you just have a direct injection pump to feed, but it plumbs the same way and uses the same quick connect adapter shown in the diagram.As a final note, GM has made some changes to the ECU in their Connect and Cruise EFI crate engine packages that permit you to delete the fuel pump driver module and use the activation wire as a trigger to a standalone relay to power an external pump using a bypass regulator. When this is done supposedly the ECU will see the driver module is not being used and will internally defeat the check engine lights associated with this. This information should be in any documentation GM is now shipping with their crate engines.
Brett Clow
Tech Director
Aeromotive, Inc.

What I think they are saying:
A: they claim no additional horsepower gains beyond 55psi of pressure on the low side
B: An appropriate high flow PWM driven fuel pump is not very expensive or difficult to find (he just bought the kit)

further, two things struck me
1. return-style system run in 'DI' mode will heat fuel up and put more wear-hours of use on the fuel pump, so PWM driven is ideal to keep
2. since the appropriate PWM driven system is frequency modulated, and even slight drop in pressure on the low side can mean very large pressure drops on the high side, the precision of PWM control at those frequencies involved must be known to design control engineers. There are many frequencies to deal with. The fuel medium may experience a noticeable water hammer frequency due to operation of the pump and the rotating speed of the pump will induce dynamic frequency waves as well, those all must be managed somehow by the PWM operation because if two frequencies happen to match they could cancel each other out and lead to lost fuel system performance or capability, or ruined components. And since everything basically vibrates, the engine and everything nearby is a potential source for 'noise' which is just waves of various amplitudes and frequencies, trying to interfere with every other wave. The pump works in 'waves' at a specific timing 'frequency' and waves can combine or cancel so we don't want to introduce any (or would prefer to introduce as little) disturbances or changes into such a ... teeter totty system if you will excuse the expression. It could be unbalanced by the slightest seemingly insignificant change. Hooking a super-battery charger to overclock the thing is hardly acceptable.

RoxyCarter

Both points A and B are very wrong when speaking on the c7/c6/c5 fuel tank.

if anyone made either one of those 2 single claims to me, I would no longer be interested in listening to another word they said concerning fueling a corvette.

listen to who you want to. But I can assure you that you won't be changing my mind, with statements like that.

atljar

First, I appreciate the on topic response with some information that was presented to you. Honestly!

However, I would ask, if pressure changes in the low side on a GM system had no influence power potential, then why would GM go through the expense of having variable pressure output? Keeping in mind that higher pressures also equals more heat. At higher loads, the ECM commands a higher low side pressure. And at lower loads, less low side pressure. Seems like a fair amount of extra engineering and programming for something that has "no effect". There are significant missing pieces of information from Aeromotive above inlcuding HP of said engine, fuel pump LPH potential, fuel line sizing and what components were used in the high side and to drive the high side. The other interesting tidbit that they mentioned is that it had no effect so long as the low side pressure is "stable". So what happens when it isnt stable which happens often these cars when you start to make power? Nothing like being under boost and have your low side dropping pressure

Next just to address something that keeps getting mentioned is Frequency modulation. These are NOT frequency modulated pumps. They are Digitally Pulse Width Modulated, hence the PWM. The PWM is a 25khz signal regardless of demand. The Frequency of the wave never changes, only the ratio of on to off times. Its also a square wave, since its digital, unlike a frequency modulation signal which is more like a sine wave. By running a voltage blaster we are only changing the amplitude of the on waves, but not frequency or pattern.

rflow306

Just saw this post. I currently have the JMS GM2 box in my car. It is activated by the factory TPS and was also worried about the led draw since my car is used mostly on the weekends. It has not made any noticeable impact on my battery charge to date. The not so good news is that the increase in fuel flow is small due to our pump. In my case with E50 and meth it was good for a consistent .2 points on the AFR scale.

You are 100 % correct about how the pump is controlled via pulse width based on the required duty cycle determined by the ecu which tells PWM when and how much to pulse the ground to the pump.

atljar

THANK YOU. Finally some first hand feedback.

Were you out of low side pump prior to the JMS? The reason I ask is....

Hypothetically, I would expect very little to no AFR change with adding the booster, unless you were out of fuel, which is more or less what you experienced. The JMS kicks on, pump starts churning out more fuel, the pressure sensor recognizes the increased pressure, and the PCM, in response, turns down the PWM to less duty time to combat the increased voltage from the JMS. In other words, did we just go from 80% duty cycle at 14v (Stock setup) to 65% duty cycle at 17v (with JMS)?

Kingtal0n

This sounds very angry. I said several times I do not know 99% of the information here. Just making points against bandaid solutions.
I also said that voltage boosters are not 'bad'. I've plenty of experience with practical application of input signal modulation.

As to safety nets. I only pointed out that one of those tried and true safety net is something like a fuel pressure safety switch for WOT. Its the same thing as having your eyes on an accurate fuel pressure gauge and being able to let off at the exact moment fuel pressure drops. This is correlatable with any fuel source whether methanol aux pump or in-tank fuel pump. It means the same thing to the system as a whole given the pressure switch operation is identical. It is not affected by frequency modulation or a slew of advanced electronics who deepest thoughts are unknown to us.

The letter from Aeromotive is from Aeromotive. Again, not my info, and I don't know whats really going on. I am barely into DI at all. Just trying to help people appreciate what the electronics are trying to do for hobbyists by simply passing on info from appropriate sources. You should not see my presence here as a threat but rather be thankful at least somebody is trying to understand all the magic inside the box, and what I see is very scary and new so forgive me if I pass some of that fear-of-unknown on in the message I write.

Finally, the frequency of the PWM driver output may not be changing; in fact it was probably set to some exact higher frequency in order to avoid all the other frequencies; this is not the issue with altering inputs to the driver.
The issue is the frequency response to those inputs, and the frequency 'modulation' if you will of the CPU inside the fuel computer, prior to the driver's actions. For example, if voltage changes, the magnitude (in Decibels, so logarithmic scale, which means 3dB is double/half) will also change in the frequency response. A control system like this has a design point around some specific range of output magnitude and phase in order to keep the 'position' component (desired pressure in this case I guess) from going out of bounds with respect to certain qualities: overshoot, rise time, peak time, oscillation, etc... which will all affect the driver in an unknown way if it wasn't anticipated or expected.

This is completely different from taking a pump designed to run at 12v all the time and simply running it at 14 or 18v. Since it runs all the time there is no cpu, there is no driver (the relay is the 'driver' I guess) and there will be no rise time, peak time, oscillations, etc... to deal with.

Kingtal0n

This is what I am worried about. Put some dirty electronics fingers into a black box for a .2 a/f ratio boost and potentially losing 30-50% of the pump's lifespan and an potential engine disaster on the horizon when the system runs into some occluded, unstable condition, it isn't worth .2 a/f ratio

rflow306

Yes on my setup with e50 and a stock cam the fuel system was/is pretty much maxed out. With the JMS my low side pressure still drops but lowest pressure is 7 to 10 psi higher than without under full load. It has definitely helped as my injector average pulse width is a little lower, i was personally hoping for more.

HessViper

what voltage are you boosted up to? What do you believe stock voltage was, 13.8 or so? Thanks for the real world experience.

rflow306

No problem. We measured as high as 14.3 volts to the factory controller. I have the JMS set to 18 volts, the gain set to max and the activation at around 80% throttle.

HessViper

so you've picked up about 4 volts and about 8psi you think?

This would solve a lot of issues for factory tune vehicles with a few bolt ons.

Factory warranty could be preserved.

HessViper

How hard was the install? Does the tank have to be lowered? Where is the booster box placed?

HessViper

Keep in mind, there is a difference between causing the car to run .2 afr points richer across the power band...

and preventing a vehicle from running out of fuel and running lean. Just because it brings everything up .2 during lower RPM when the high side pump is the ultimate dictator, does not mean it may not supply an extra 100+ hp worth of fuel up top when the stock voltage system starts to fall off.

Keep in mind, the car might make another 70hp to get the fuel pressure back down the 7psi, to where it was before the add on. He is obviously making more power now than he was before the add on, so lets be modest and say it is 30hp vs before the voltage booster mod.

He is 7psi above where he was before on the low side. If he added 70hp worth of air flowing power adders, then he MIGHT be back to the same low side PSI he was before the voltage booster mod.

Thus, it can be said, the voltage booster picked him up 100hp worth of fueling. And when the high side pump is doing its job to govern fueling, the extra pressure still causes the car to run .2 points richer on the same apples to apples tune.

I hope this makes sense.

rflow306

Install was easy, it goes next to the controller under the rear hatch floor cover, The hardest part was running the wire to the tps. If i had to drop the tank i would go Fore Triple pump.

Kingtal0n

I said that extremely poorly, yes. 0.0 a/f difference is possible with +100hp but you probably wouldn't want the same a/f ratio anyways. So the 'difference' aspect is negligible in this context. Sorry about that.
I just meant to that I was worried about seeking some small improvement at what unknown costs to some extremely complicated electronics. You know, people will buy anything. Even if its bad for them.

Kingtal0n

I was under the impression the low side pressure was never supposed to change. I know for certain there are some DI years run a constant low side pressure. I am not sure which system or when it was changed.
In any case; I always tell everyone the lower the pressure, the better, in general. That goes for any fluid system, blood pressure, fuel pressure, oil pressure, etc... The less pressure is less stress. Nevermind 'heat' or even trying to use that term here. If pressure is reduced for low loads, then that is identical to how regulated 100% non-pwm driven fuel systems also work. There is nothing 'new', GM did not didn't 'go through any expense to have variable pressure' because its been that way since 1984. Only in the new emissions standards years, for whatever reason around 98-02 they removed the return line and called it 'returnless' even though there was still a return at the tank, and fuel pressure was held constant. However that only remains true for the rail pressure; the true 'fuel pressure' is also based on engine manifold pressure (for port injection) so fuel rate constantly needed to be calculated (the fuel injector flow rate) by the computer based on a pressure-table that I can share if you havn't seen it. Suffice to say this was done in 98-02, and also isn't 'new', and the whole point of PWM is not having to run the pump at full power all the time anyways, regardless of how much pressure is demanded. In other words, the fuel pump life and fuel system life may be longer due to the fact the pump is PWM driven, with respect to how much life is gained by running at it with a lower pressure could provide. The prospect of doing it with a fuel pump under PWM control is enticing to me because it would be superior to any pressure-regulated system (response time in a pressure-reference system is slow whereas pressure compensation response time for engine demands via properly placed electronic sensors (DI injection) is extremely fast) so I am all in favor of PWM control almost no matter what the application is.

Yes I agree he leaves a bit unsaid. The pressure of the system for example has no bearing on flow rate. It could be at 5psi and still support 1000 horsepower. I think all he means is that the high side pump isn't going to do anything magical at low side pressures over 60psi, where actual supported power total (flow rate overall) is indifferent.

Just to re-survey this. PWM from the driver is set some specific frequency and this is not my concern at all. When the engineers first design the system on paper, and then test the real thing, they would command it in open loop to test the systems frequency response, that is the output magnitude compared to the input frequency from the cpu to the driver. This data is then used to modify the system until it 'looks great on paper for the application' not sure how else to say it. And then they close the loop and check system bandwidth and a ton of other variables. And this may have went round and around until they hit all the design criterion, a blend of control, stability, performance that was adequate. It is incredible how delicate that balance is. If just one variable is changed the system may become unstable. It depends how it was programmed, what the engineers expect/ are expecting people to do with it. It is impossible to predict what can happen. I'm the type to 'keep it simple' and something like this is a red flag for tampering, as complicated as it gets, a pump computer must predict engine demand extremely accurately in terms of frequency and response for the pump in question through a driver. Those changes to conditions are not so much 'sensed and responded to' the way a traditional referenced regulator is- that would be slow. Instead, they are predicted from known constants, previous tests at typical operating voltage ranges for example that the computer relies on to make future decisions. If we come along and change anything- then those previous tests may become meaningless, and future predictions may no longer be accurate. the closed loop system might compensate, or it might just flip out and do whatever it wants.

RoxyCarter

Even if the pressure was to never change in the low side line, the rate of pumping the in tank pump would have to do would have to increase and decrease based on the flow/draw from the high side pump.

this is why the aeromotive in tank pumps are not a great solution, as they are always on full blast relative to the stock pump, and produce way too much heat for sustained long running in the small drivers tank, and heat up their fuel they are in, which results in cavitation, and pump getting too hot.

Kingtal0n

actually the pump aeromotive supplies is PWM compatible. Otherwise it wouldn't be a good option, and it would heat up the fuel just like all cars do before PWM DI was initiated.
Adding port injection is the solution. Stand-alone DI isn't on serious performance cars anymore. That was a mistake for a couple years and they will never repeat that mistake, like optispark and crossfire its gone.

RoxyCarter

Correct.

higher hp, yes.

stock cars with a few simple bolt ons trying to avoid p0089 and p228c, need just a little more fuel.

port injection is expensive.

Members of our team are strong advocates for port injection, while other vendors were trying to dispute and push higher flow DI injectors and high side pumps and cam lobes, months and years ago, certain people on our team countered and said port injection was the superior route. This was long ago.

we have been Chris Crawford fans before most people in this forum knew his name, let alone the quality of his products and services. Same for weaponX whonwas the first to do the whipple2.9

you aren't teaching us anything we don't already know, and agree with.

you keep flopping around, changing the topic, when this thread and this voltage booster have a niche purpose and a place in the marketplace, if the small bugs can be ironed out.

guys who need to pick up about 100hp worth of fuel, and are happy at 100hp above the stock fuel systems current peak limits, this will be the most cost effective solution... both up front, and maintenance, and warranty preservation. It is THE BEST route to go.

but you are right, after re reading my comment, it looks as if I don't understand the aeromotives is pwm... I understand that it is, but I also believe it creates more heat and is less reliable, and will fail sooner than the stock pump, and lowering the tank for installation and again for replacement, is on the consumer's dollar.