Advancement of fuel delivery?

[Alky V6]

I thought you were set on adding the second pump Donnie? What changed your mind, or have you just not gotten to it yet.

At one point I had contacted Kinsler about larger nozzles. After explaining my fuel system to them, they were surprised that the pump I'm using was at the limit. They suggested some how restricting the return line to raise fuel pressure. So I decided that before I add the other fuel pump, I wanted to get a true blue picture of what the fuel pressure is really doing with the single pump. I just need to zoom in better on the gauge next time. If I find that the fuel pressure is referencing correctly to boost with no drop on the top end, then the fuel pump is not the problem. I just need the pressure higher at the higher boost level.

 

[Alky V6]

TEC unit map pressure conversion

TEC3r using WinTEC4 software.

Atm = 93.5 kPa TEC unit readout.

Maximum map reading obtainable with the TEC unit using a GM 3 bar map sensor = 314 kPa.

314 - 93.5 = 220.5 maximum boost value able to be logged by the TEC unit.

220.5 kPa = 31.98 psi

So the boost was well past 32 psi.

The next specs are for a HKS GTII 60mm wastegate.
The spring package that was in the wastegate was for a boost range of 24 to 30 psi. Blue/Pink, Blue/Green, Blue/Red springs. The adjuster screw backed all the way off.
The new spring package will be for a range of 8.5 to 14 psi. Blue/Pink spring only. The adjuster screw will be backed all the way off.

Another note about the video. On the top end after the 1-2 shift you'll notice that the engine woke up just before I got off the throttle. That's where the a/f was leaning from 10.17 to 10.9:1. I think a good safe target reading for my setup will be 10.5 to 10.7:1.

 

[Alky V6]

More notes on the video pass.
Aux fueling turned on at 5,783 rpm @ 149 kPa.
Nitrous shut down at 5,971 rpm @ 161 kPa. When the nitrous shut down, there was a sharp increase in rpm climb rate. A good sign that too much nitrous retard (net of 8 degrees btdc) is happening. But, we already knew that. Actually, I think this is where the tires broke loose. Yep. Looks like when the timing came back in (net 24 degrees btdc) the tires elected to smokith.
The only sign that the aux system has turned on is by a drop in the a/f ratio (somewhere between 5923@153 - 5975@161), off of the flatlined lean reading with the nitrous on from 4,000 rpm to that point. The drop was from 14.64 to 10.98:1. Then a further drop to 10.17:1 by 6245@198kPa on the start of the top end charge with the cutback e injector pw.

As can be seen in the video, I don't need anymore total ignition advance timing on the top end.

 

[Dusty Bradford]

If your using 160's, maybe it's time to look into Moran's billet 220# or larger injectors. This would allow you to tune with the laptop rather than using mechanical means. I have a source for them if your interested.

 

[Alky V6]

Need exhaust back pressure reading

I'll keep it in mind, Dusty.
I think the fueling will be OK if I can get the boost level down where it's supposed to be.

Note to self.
Get a video of the exhaust back pressure gauge.

 

[Alky V6]

EFI fuel control. The fuel pressure is kept constant or rises with manifold pressure in a linear curve in relation to MAP. A smooth and straight ramp up actually, in relation to MAP. The amount of fuel delivered at different rpm/map points is dependent on the amount of pulse width commanded electronically of the injector.

Mechanical fuel control. The fuel nozzle orifices are a fixed diameter. There is no control of the orifice size or how long it's turned on or off. Typically, the fuel is constantly flowing when the engine is running. The amount of fuel delivered at different rpm/map points is dependant on the speed of a mechnical fuel pump, usually driven at half crankshaft speed, which controls volume and pressure, and mechanically or electrically controlled bypass valves which control the fuel supply pressure at the nozzles. The fuel pressure delivery curve, as seen by the nozzle is not linear, but changes in rate, or levels out at different rpm, and in some cases map, breakpoints.

My system being a combination of both in a way, uses pw to control fuel delivery through the electronic injectors using a linear ramp up of fuel supply pressure, and obviously requires a modification of the fuel supply pressure off the linear curve on the top end to satisfy the needs of the fixed orifice mechanical nozzles.

I posted this to hopefully make more clear my fuel delivery problem to some that may be lost with what is happening.

What would solve my dilemma is a device that would modify the pressure rise curve off the now linear path, after 280 kPa (or start sooner for that matter), and make the rise faster in relation to manifold pressure. Isn't that what FMUs do?

 

[Dusty Bradford]

What would solve my dilemma is a device that would modify the pressure rise curve off the now linear path, after 280 kPa (or start sooner for that matter), and make the rise faster in relation to manifold pressure. Isn't that what FMUs do?

So your thinking that as boost reaches a certain point, your mechanical nozzles aren't flowing enough fuel and your out of duty cycle with the electronic injectors? Does the mechanical pump feed the injectors and nozzles?

Are you wanting a non linear rise on both electronic and mechanical nozzles?

 

[Alky V6]

So your thinking that as boost reaches a certain point, your mechanical nozzles aren't flowing enough fuel and your out of duty cycle with the electronic injectors? Does the mechanical pump feed the injectors and nozzles?

Are you wanting a non linear rise on both electronic and mechanical nozzles?

You're starting to catch on, Dusty.
I'm not running a mechanical fuel pump. I'm running a large electrical pump. There lies my problem with the mechanical fuel nozzles. The nozzles are not getting the benefit of a rising volume and pressure pump like they would see with a mechanical fuel pump.
The electric pump setup is supplying a fixed volume and pressure across both injector (electronic and mechanical) deltas. The electronic injectors can make up for it with increasing pw up to the point of running out of duty cycle. At the point of running out of duty cycle, the perfect thing to happen then would be for the fuel supply pressure to start ramping at a steeper rate in relation to manifold pressure. Both the electronic injectors and the mechanical nozzles would then be able to supply a steeper ramp up of fuel volume across the injector and nozzle deltas in relation to manifold pressure. Instead of the typical 1 to 1 ratio, fuel pressure to manifold pressure that's typical of referenced fuel regulators, the ramp up would start taking on a different ratio that would supply more fuel in relation to manifold pressure.

The fix sounds easy, and the device to accomplish it sounds easy. I wonder if anyone has such a device that can be brought into play at an adjustable manifold pressure point. A feature that allows for an adjustable fuel pressure to MAP ratio would also make for the perfect solution.

 

[Dusty Bradford]

I don't know of such a device.

It would have to swap ratio's at a certain point or else your whole tune to this point is wasted if you went to a 2:1 regulator. At that point, I'd be concerned that your fuel pump would not supply the volume at pressures of 100+ psi.

Then there's the question of how much pressure is needed. Is it possible you'd run out of fuel volume before the pressure was raised enough to deliver the right amount of fuel.......

To me, the simplest fix is also the easiest to tune and the most precise method of fuel delivery. Properly sized electronic injectors. The new billet injectors are much easier to tune down low. They act much like a 160 but flow mucho more up top.

 

[Alky V6]

I don't know of such a device.

It would have to swap ratio's at a certain point or else your whole tune to this point is wasted if you went to a 2:1 regulator. At that point, I'd be concerned that your fuel pump would not supply the volume at pressures of 100+ psi.

Then there's the question of how much pressure is needed. Is it possible you'd run out of fuel volume before the pressure was raised enough to deliver the right amount of fuel.......

To me, the simplest fix is also the easiest to tune and the most precise method of fuel delivery. Properly sized electronic injectors. The new billet injectors are much easier to tune down low. They act much like a 160 but flow mucho more up top.

Probably only needing an increase from 75-80 to 85-90 psi.

A 2 to 1 ratio change is probably too much. That's why an adjustable feature would be trick.

Good question on the volume to pressure relationship. Electric pumps tend to supply less volume as pressure is raised.

Have they solved the sticking problem with the Moran's?

I would need an injector that behaves like a 160 down low but delivers 260 to 280 up top.

 

[charlief1]

Don't know if you could make it work or not but I have an idea for the mechanical pump. I'm sure you know what a variable speed pump is, but have you ever seen a cvct tranny? Using 2 spring loaded pulleys that are able to change their sizes as rpm changes it allows for a higher speed/ratio of the pulleys. You'd have to make it yourself I'm sure but it would allow for a variable volume as the speed of the pulleys change. I doubt it would work but I thought I'd throw it out there.

 

[Alky V6]

Don't know if you could make it work or not but I have an idea for the mechanical pump. I'm sure you know what a variable speed pump is, but have you ever seen a cvct tranny? Using 2 spring loaded pulleys that are able to change their sizes as rpm changes it allows for a higher speed/ratio of the pulleys. You'd have to make it yourself I'm sure but it would allow for a variable volume as the speed of the pulleys change. I doubt it would work but I thought I'd throw it out there.

A basic mechanical fuel pump would do the job. I just don't have the room to mount and drive one.

Here's an idea. Thought of it while in the shower just now. A mechanical injection type of trick.
In the fuel return line, after the fuel regulator, near the fuel cell, 'Y' the return line into two parallel running return lines. In one of these lines have a 'normally open' electric bypass valve. In the other line, place a 'jet can' or an adjustable orifice setup like a needle and seat. The bypass valve would be programmed to shut flow down at a certain MAP, forcing all the return fuel to flow through the 'jet can' or other orifice setup. The size of the orifice would initially start out large and then be adjusted down smaller until the desired back pressure on the fuel system is achieved that will supply the required fuel. After the the bypass and 'jet can', the two parallel lines would 'Y' into a single line again to finish flowing to the fuel cell.

I know this would result in a quick step up of fuel volume, but I only need 3 to 4 percent more volume at the most, on the top end. I don't think that small of a step-up in volume would upset the engine much. Especially if the engine is needing it. Trying to drop the a/f on the top end from 10.9:1 to 10.5:1 (4.8:1 to 4.63:1).

Since electric bypass valves aren't known for flowing much, it might be necessary to split the return line into 3 lines and run two electrically operated, 'normally open' bypass valves and one 'jet can'.

I'm presently using such an electric bypass valve to control flow to the aux fuel system. It's a 'normally closed' bypass valve.

 

[Dusty Bradford]

Probably only needing an increase from 75-80 to 85-90 psi.

A 2 to 1 ratio change is probably too much. That's why an adjustable feature would be trick.

Good question on the volume to pressure relationship. Electric pumps tend to supply less volume as pressure is raised.

Have they solved the sticking problem with the Moran's?

I would need an injector that behaves like a 160 down low but delivers 260 to 280 up top.

I agree. 2:1 would be to drastic of a change and I feel you'd run into issues with the electric pump supplying enough volume at those pressures.

I'm seeing more and more of the Moran's verses the 212's. People like the idle tunability with the Moran's. The guys I have spoken with at the track about them, speak highly of them.

 

[Alky V6]

I looked up the calibration paperwork I received with the Weldon 2345-A electric pump. The flow difference is 271 GPH @ 70, 18 amp draw, to 265.5 GPH @ 80 psi, 19 amp draw. I think the pump will do the job if those numbers hold up.
We need to wait and see exactly what the fuel pressure is doing on the top end.

 

[Alky V6]

60' reference notes

The best 60' off the nitrous was 2.32. The pass just before going to the nitrous.
The best 60' on the nitrous, which happened to be the first pass with the nitrous and with the massive lean reading from 4,000 rpm on to the point the nitrous turned off was 1.637.
The next pass where the nitrous region was richened a bit gave a 1.687 60', even though the data log showed a quicker rpm rise.

 

[charlief1]

I know you've been over this before Donnie but the best solution is adding the second pump as an aux system. If you had a second line feeding the mechanical injectors that would turn on at a specific pressure that should solve the problem, right?

 

[Alky V6]

I know you've been over this before Donnie but the best solution is adding the second pump as an aux system. If you had a second line feeding the mechanical injectors that would turn on at a specific pressure that should solve the problem, right?

If I had the aux turn on at a higher pressure, it would mean a higher lean spike while the air is purging from the system, which would require a larger shot of fuel from the e injectors to cover the lean spike. It would also require that the e injectors be cut back even further than they presently are being cut back. In both cases, the e injectors are being operated at max limits above and below the basic fuel curve that the ECM will allow to cover the lean spike and the cut back. What would work best is if the aux system came on with less pressure than the e injector system and then ramped up in relation to manifold pressure at a steeper rate. That would mean a shorter 'wall' to cover the air purge lean spike and not as much cut back of the e injectors. Then the pressure would ramp up at a steeper rate to supply enough fuel on the top end to prevent running out of pw with the e injectors.

The problem is, finding referenced regulators with more than a 1 to 1 ratio.

 

[charlief1]

I may have the wrong term but what about an adjustable Hobbs switch. You could set the pressure that would trigger the second pump that way. Another idea is to be able to turn the pumps on before you leave the pits to help purge the lines first.

 

[Alky V6]

I may have the wrong term but what about an adjustable Hobbs switch. You could set the pressure that would trigger the second pump that way. Another idea is to be able to turn the pumps on before you leave the pits to help purge the lines first.

I have an unused ECM GPO that I can use for the second pump, if it comes to that.

I've mentioned the idea of purging the aux fuel system before, and frankly the idea slipped my mind. Thanks for bringing that up. I'm seriously considering wiring that up. If I could considerably lessen the size of 'the wall', I could gain quite a bit of range for the cut back section of the VE table. Right now, I'm running into a problem of not being able to cut back the e injectors enough to properly lean the mixture between 160 kPa and 190 kPa. That's the start of the cut back region right after 'the wall'. Any VE table range that I can gain by lessening 'the wall', I can transfer directly over to the cut back region.

 

[Alky V6]

Tuning notes

Things really start happening at 4500 @ 110 kPa with the nitrous. That would be about 2.4 psi. Boost and rpm ramp up is very quick from this point on. The elapsed time from transbrake release to 4500/110 is 1.64 seconds (21a.dat).
Work has started adding a quick spool valve to the T4/T6 adapter flange to take advantage of the split turbine housing.