May have solved 100% E85 on LNF puzzle
03-07-2011 | 11:54 PM
#76
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
Nice work, Vince. This is going to a nice step in the direction of 600whp LNFs. 
On the topic of low pressure DTCs, it is not the low pressure pump that comes up short. At least on my car, it happens when the mechanical pump is not spinning fast enough to deliver enough fuel. Because the mechanical pump is positive displacement and directly proportional to engine speed, this limitation would be directly correlated with torque rather than horsepower. To test this, we put a pressure gauge on the inlet of the mechanical pump and ran E98 in the tank. Every time the boost came in, the rail pressure would climb to 2400 or so, then drop to less than 1500 while IDC shot up well past 40%. While all this was going on, the fuel pressure at the mechanical pump inlet remained at 60psi the whole time. To further support these findings, we have been running our secondary fuel rail and supporting over 400 whp on E85 with the stock pump still in the tank. It still maintains 60psi at the mechanical pump inlet.
In other words, don't everyone go out and buy a Walbro tomorrow! It won't change anything.
On the topic of low pressure DTCs, it is not the low pressure pump that comes up short. At least on my car, it happens when the mechanical pump is not spinning fast enough to deliver enough fuel. Because the mechanical pump is positive displacement and directly proportional to engine speed, this limitation would be directly correlated with torque rather than horsepower. To test this, we put a pressure gauge on the inlet of the mechanical pump and ran E98 in the tank. Every time the boost came in, the rail pressure would climb to 2400 or so, then drop to less than 1500 while IDC shot up well past 40%. While all this was going on, the fuel pressure at the mechanical pump inlet remained at 60psi the whole time. To further support these findings, we have been running our secondary fuel rail and supporting over 400 whp on E85 with the stock pump still in the tank. It still maintains 60psi at the mechanical pump inlet.
In other words, don't everyone go out and buy a Walbro tomorrow! It won't change anything.
03-07-2011 | 11:55 PM
#77
Senior Member
Joined: 07-23-10
Posts: 3,451
Likes: 0
From: Carlsbad, CA
Damn you MATT for bursting my bubble LOL... So wtf is up with the fueling then?
Last edited by RyRidesMotox; 03-08-2011 at 12:02 AM.
03-08-2011 | 12:06 AM
#79
I'm not convinced the problem is the supply pump, I undid the soft lines (plastic line, largest available diameter in engine bay) and was able to openly flow 2 liters in 22 seconds. The walbro pump according to summit is rated 255lph @0 psi. I know for a fact it's more than enough for 700 plus horspower so it's a non issue. But open flow at slightly less than 6 liters per minute tells me the pump isn't the problem, because then your talking conservatively 300+ liters per hour. If the real choke point isn't obvious to you just look at the hard line that feeds the hpfp, particularly the point where the stainless line is brazed into the formed compression fitting. That cannot be more than 3/32" it's likely less than that. At 100 psi I can see how it can cavitate the pump and thus produce a low rail pressure. Feeding the HPFP at a higher pressure, even 135 or so would probably eliminate the problems exposed here. You would need a mechanical pressure regulator, and to braze the device into the hard lines with the isolator to prevent diaphragm failure in the regulator.
edit:I meant 60psi for some reason im thinking about my dodge on a seperate fueling problem.
edit:I meant 60psi for some reason im thinking about my dodge on a seperate fueling problem.
Last edited by army_greywolf; 03-08-2011 at 12:12 AM.
03-08-2011 | 12:12 AM
#80
Thread Starter
Member
Joined: 04-09-08
Posts: 377
Likes: 0
From: Seattle, WA
Nice work, Vince. This is going to a nice step in the direction of 600whp LNFs.
On the topic of low pressure DTCs, it is not the low pressure pump that comes up short. At least on my car, it happens when the mechanical pump is not spinning fast enough to deliver enough fuel. Because the mechanical pump is positive displacement and directly proportional to engine speed, this limitation would be directly correlated with torque rather than horsepower. To test this, we put a pressure gauge on the inlet of the mechanical pump and ran E98 in the tank. Every time the boost came in, the rail pressure would climb to 2400 or so, then drop to less than 1500 while IDC shot up well past 40%. While all this was going on, the fuel pressure at the mechanical pump inlet remained at 60psi the whole time. To further support these findings, we have been running our secondary fuel rail and supporting over 400 whp on E85 with the stock pump still in the tank. It still maintains 60psi at the mechanical pump inlet.
In other words, don't everyone go out and buy a Walbro tomorrow! It won't change anything.
On the topic of low pressure DTCs, it is not the low pressure pump that comes up short. At least on my car, it happens when the mechanical pump is not spinning fast enough to deliver enough fuel. Because the mechanical pump is positive displacement and directly proportional to engine speed, this limitation would be directly correlated with torque rather than horsepower. To test this, we put a pressure gauge on the inlet of the mechanical pump and ran E98 in the tank. Every time the boost came in, the rail pressure would climb to 2400 or so, then drop to less than 1500 while IDC shot up well past 40%. While all this was going on, the fuel pressure at the mechanical pump inlet remained at 60psi the whole time. To further support these findings, we have been running our secondary fuel rail and supporting over 400 whp on E85 with the stock pump still in the tank. It still maintains 60psi at the mechanical pump inlet.
In other words, don't everyone go out and buy a Walbro tomorrow! It won't change anything.
I CAN at least say it fixed the problem on several V6 SIDI vehicles that were aftermarket-turbocharged that ran into this issue.
We may need to make some changes to the fuel rail pressure control stuff in the ECM (e.g. regulator commanded position, etc.)
03-08-2011 | 12:13 AM
#81
03-08-2011 | 12:14 AM
#82
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
I'm not convinced the problem is the supply pump, I undid the soft lines (plastic line, largest available diameter in engine bay) and was able to openly flow 2 liters in 22 seconds. The walbro pump according to summit is rated 255lph @0 psi. I know for a fact it's more than enough for 700 plus horspower so it's a non issue. But open flow at slightly less than 6 liters per minute tells me the pump isn't the problem, because then your talking conservatively 300+ liters per hour. If the real choke point isn't obvious to you just look at the hard line that feeds the hpfp, particularly the point where the stainless line is brazed into the formed compression fitting. That cannot be more than 3/32" it's likely less than that. At 100 psi I can see how it can cavitate the pump and thus produce a low rail pressure. Feeding the HPFP at a higher pressure, even 135 or so would probably eliminate the problems exposed here. You would need a mechanical pressure regulator, and to braze the device into the hard lines with the isolator to prevent diaphragm failure in the regulator.
This new tuning capability that Vince has come up with is going to make significant improvements in the higher RPMs, but we will still need to bring in the boost a little later than the stock turbo is capable of spooling. Next on the list we should explore mechanical pump upgrades.
03-08-2011 | 12:20 AM
#84
Senior Member
Joined: 12-06-06
Posts: 1,291
Likes: 0
From: Saskatoon, SK
03-08-2011 | 12:20 AM
#85
im aware of the low rpm problem, but hell, what are we doing throwing that much power at it below 4 grand in the first place. I'd like to take a pump apart to see if it can be overbored, if anyone has one to donate, I'll see how far I can go with it.
03-08-2011 | 12:30 AM
#87
no offense but used ppe pumps pop up on racingjunk and ebay all the time for 350-500. Not to mention you can get JUST a cp3 and have it modified at a machine shop for belt drive yourself for less than that. The REAL problem then is accurately regulating it's output pressure, since it can drive almost 30,000 psi.
03-08-2011 | 12:36 AM
#88
03-08-2011 | 12:44 AM
#89
Senior Member
Joined: 07-23-10
Posts: 3,451
Likes: 0
From: Carlsbad, CA
You can run E85 on an lnf just not straight E85. Like I said before LSJs can run E85 straight with larger injectors we in the LNF world cannot.
03-08-2011 | 12:47 AM
#90
Senior Member
Joined: 10-13-10
Posts: 598
Likes: 0
From: Washougal, WA
03-08-2011 | 01:15 AM
#92
Well if this works, I may be getting a TF/HP tune combo in the near future, gotta start sourcing out E85 stations in the area, if I can find them, don't seem to be many in Ohio. Vince, think a switchable E85/93 tune would be possible? That's be probably the best solution possible.
03-08-2011 | 05:50 AM
#93
I have a question...
Has anyone shown conclusive benefit to increasing the ethanol percentage over say 50%? There have been a few studies done on ethanol and compression ratio, mpg, timing, kr and power output and it seems to me they were finding diminishing returns on mixes over as low as 30-40% ethanol. Several of the studies were even done using the LNF engines. Basic findings (that I can remember) are that the LNF is most definitely "knock limited" on pump gas, which we already knew. This means there's no way you can get to MBT on 91 octane fuel. MBT I believe was reached with far less than 100% ethanol, I think it might have been below 50% even.
Fuel mileage had similar findings, highest mpg was reached not at straight pump gas, but at somewhere around 20-30% ethanol. This obviously was because of being able to run more timing, but once you're at the timing that would give the best mpg, and the octane to keep kr at bay, there is no reason or need to go higher on ethanol to reduce knock.
Sooooo, my question is like I said, has anyone shown that E85 makes more power than say E48 in the LNF? I know mpg's will keep going down over 50% or so, but I know that's not what most of us are looking for here. My personal experience, gathered information and my own testing has led me to believe between 35% and 55% ethanol is all that's needed to make good power and decent efficiency. The engineers, professors and engineering students that put those studies together seemed to say the same thing. I believe it's just like octane, you only want as much as you need to control kr, and no more. Raising octane levels higher than needed creates less power.
Has anyone shown conclusive benefit to increasing the ethanol percentage over say 50%? There have been a few studies done on ethanol and compression ratio, mpg, timing, kr and power output and it seems to me they were finding diminishing returns on mixes over as low as 30-40% ethanol. Several of the studies were even done using the LNF engines. Basic findings (that I can remember) are that the LNF is most definitely "knock limited" on pump gas, which we already knew. This means there's no way you can get to MBT on 91 octane fuel. MBT I believe was reached with far less than 100% ethanol, I think it might have been below 50% even.
Fuel mileage had similar findings, highest mpg was reached not at straight pump gas, but at somewhere around 20-30% ethanol. This obviously was because of being able to run more timing, but once you're at the timing that would give the best mpg, and the octane to keep kr at bay, there is no reason or need to go higher on ethanol to reduce knock.
Sooooo, my question is like I said, has anyone shown that E85 makes more power than say E48 in the LNF? I know mpg's will keep going down over 50% or so, but I know that's not what most of us are looking for here. My personal experience, gathered information and my own testing has led me to believe between 35% and 55% ethanol is all that's needed to make good power and decent efficiency. The engineers, professors and engineering students that put those studies together seemed to say the same thing. I believe it's just like octane, you only want as much as you need to control kr, and no more. Raising octane levels higher than needed creates less power.
If the same power can be made on E85, it will provide less hassle at the pump than my current split fuel fill ups. I doubt I'll be able to run full E85 with my Low Fuel Rail pressure CEL issues, but time will tell if Vince can work around that.
Last edited by Iam Broke; 03-08-2011 at 08:34 AM.
03-08-2011 | 08:39 AM
#94
Mine will start fine in colder weather with about 10* added cranking advance with the 60% blend.
03-08-2011 | 09:02 AM
#95
Gimpster ran E85 on an LNF stock sedan late last summer. He had enough fueling stock after shifting the MAF cal over 30% to get enough fuel. Starting became an issue when it got below 45*f. He emailed myself and others about it, not sure if he ever posted in HPT. Sadly he has moved on to another platform.
Mine will start fine in colder weather with about 10* added cranking advance with the 60% blend.
Mine will start fine in colder weather with about 10* added cranking advance with the 60% blend.
03-08-2011 | 09:07 AM
#96
Also people have been using the E85 blend with the help of the trifecta base file too. So I don't know why you are swinging from the HP Tuner nuts so hard.
03-08-2011 | 09:13 AM
#97
Former Vendor
Joined: 06-03-08
Posts: 4,169
Likes: 8
From: Grand Rapids, MI
In my testing of 25 through 70% E, I didn't see any performance gains on my 60-100 times once I got above 47%, but you knew that already.
If the same power can be made on E85, it will provide less hassle at the pump than my current split fuel fill ups. I doubt I'll be able to run full E85 with my Low Fuel Rail pressure CEL issues, but time will tell if Vince can work around that.
If the same power can be made on E85, it will provide less hassle at the pump than my current split fuel fill ups. I doubt I'll be able to run full E85 with my Low Fuel Rail pressure CEL issues, but time will tell if Vince can work around that.
03-08-2011 | 10:36 AM
#99
Once you have surpassed a certain duty cycle, the gains to adding more ethanol quickly diminish. Basically, you haven't run into misfires yet at that point, but the late injection is still having a negative affect on performance. It's a gradual curve, so it will appear that there simply is no gain to adding more ethanol. Now that you can inject sooner, you should see gains going beyond 50% E. Remember that you have to continue to get more aggressive with the tune as you progress into a higher percentage of E as well.
03-08-2011 | 10:44 AM
#100
New Member
Joined: 11-04-06
Posts: 14
Likes: 0
From: Chicago
I am happy to report that we may have figured out (what should be) the last piece of the puzzle of running 100% E85 on the LNF. It's subject to further development and testing, but we seemed to have gotten past a major milestone.
I was actually reviewing a post on another lnf tech forum yesterday, from 2009 around the time when we sorted out the fuel rail pressure stuff. The post seemed to imply that the only way to increase fuel flow on the LNF was to raise the rail pressure because the injection window (amount of time we have to inject fuel on the LNF) was fixed. It also seemed to imply that the problem with injection window size was due to injection carrying over into the compression stroke and that going outside the injection window meant injecting fuel while the exhaust valve was still open causing soot build-up due to an improper combustion.
This implies that the ECM has a hard-set STOP injection point, and calculates the start of injection backwards from this point, meaning that any "time" that needs to be added goes onto the front of the injection pulse.
I don't believe this accurately describes what is happening, and maybe this has been debated here, already - if it has, I apologize for rehashing old discussions.
After some interesting discussions with the guys at ZZP who have more hands-on experience exercising the fuel supply limits of the LNF than I do, it started to sound like the problem wasn't the injection pulse starting too early, but rather it was ending too late - e.g. the injection is still happening when the ECM was trying to ignite the air-fuel charge! There is some math to explain this:
I've heard various numbers - some say injection window misfire sets in at "around 5.5ms" but I got some more detailed information from ZZP - they say that injection window misfire sets in at around 35% injector duty cycle, which is a more accurate way to describe the issue because it takes RPM into account. For example, at 7000 RPM, this would be 6ms.
We can use this figure of 35% IDC to estimate when the LNF starts its injection cycle. There are 720* of crankshaft rotation for all strokes, so 35% of this, or 720 * .35 = 252*. We also have to take into account ignition timing, which happens at, conservatively, 15* BTDC. So we add 15* to our 252*, and that puts the estimated start point of injection at around 267* BTDC.
It would seem this also dispels the theory that carrying over the injection into compression stroke is what causes injection window misfire. There is only 180* of crankshaft rotation from TDC (start of intake stroke) to BDC (start of compression stroke), but we can hit as much as 252* of injection window.
Our injection window size, could be, in theory, accounting for, say 20* of spark advance, 360 - 20 = 340* which would be 47% IDC, and 8ms (33% more fuel mass even at 7000 RPM!). The reality is, though, due to cam phasing events (e.g. exhaust valve still open - we don't want to spray fuel while the exhaust valve is still open), the window would likely be less than 340* maximum. But, then again, maybe we can get there - the LF1 engine (SIDI 3.0L V6) starts its injection almost that early.
With regard to running E85, raising the fuel rail pressure has helped us immensely, but that only shortens the required pulsewidth, it doesn't increase window size, and to run 100% E85 we need as much as 40% more fuel mass, and cranking the rail pressure up all the way doesn't *quite* get us there. I am Broke got somewhere around 67% E85 I believe with rail pressure at highest.
So, to summarize, by combining raised fuel rail pressure and changing the start of injection point on the LNF, we can increase the fuel flow potential, likely enough to run 100% E85 on the LNF. This is the part that we believe we've sorted out now. I'll be working on testing over the next few days, and a few people have offered to help test this out.
If it works out, we could be running 100% E85 in our LNFs within a matter of weeks.
I was actually reviewing a post on another lnf tech forum yesterday, from 2009 around the time when we sorted out the fuel rail pressure stuff. The post seemed to imply that the only way to increase fuel flow on the LNF was to raise the rail pressure because the injection window (amount of time we have to inject fuel on the LNF) was fixed. It also seemed to imply that the problem with injection window size was due to injection carrying over into the compression stroke and that going outside the injection window meant injecting fuel while the exhaust valve was still open causing soot build-up due to an improper combustion.
This implies that the ECM has a hard-set STOP injection point, and calculates the start of injection backwards from this point, meaning that any "time" that needs to be added goes onto the front of the injection pulse.
I don't believe this accurately describes what is happening, and maybe this has been debated here, already - if it has, I apologize for rehashing old discussions.
After some interesting discussions with the guys at ZZP who have more hands-on experience exercising the fuel supply limits of the LNF than I do, it started to sound like the problem wasn't the injection pulse starting too early, but rather it was ending too late - e.g. the injection is still happening when the ECM was trying to ignite the air-fuel charge! There is some math to explain this:
I've heard various numbers - some say injection window misfire sets in at "around 5.5ms" but I got some more detailed information from ZZP - they say that injection window misfire sets in at around 35% injector duty cycle, which is a more accurate way to describe the issue because it takes RPM into account. For example, at 7000 RPM, this would be 6ms.
We can use this figure of 35% IDC to estimate when the LNF starts its injection cycle. There are 720* of crankshaft rotation for all strokes, so 35% of this, or 720 * .35 = 252*. We also have to take into account ignition timing, which happens at, conservatively, 15* BTDC. So we add 15* to our 252*, and that puts the estimated start point of injection at around 267* BTDC.
It would seem this also dispels the theory that carrying over the injection into compression stroke is what causes injection window misfire. There is only 180* of crankshaft rotation from TDC (start of intake stroke) to BDC (start of compression stroke), but we can hit as much as 252* of injection window.
Our injection window size, could be, in theory, accounting for, say 20* of spark advance, 360 - 20 = 340* which would be 47% IDC, and 8ms (33% more fuel mass even at 7000 RPM!). The reality is, though, due to cam phasing events (e.g. exhaust valve still open - we don't want to spray fuel while the exhaust valve is still open), the window would likely be less than 340* maximum. But, then again, maybe we can get there - the LF1 engine (SIDI 3.0L V6) starts its injection almost that early.
With regard to running E85, raising the fuel rail pressure has helped us immensely, but that only shortens the required pulsewidth, it doesn't increase window size, and to run 100% E85 we need as much as 40% more fuel mass, and cranking the rail pressure up all the way doesn't *quite* get us there. I am Broke got somewhere around 67% E85 I believe with rail pressure at highest.
So, to summarize, by combining raised fuel rail pressure and changing the start of injection point on the LNF, we can increase the fuel flow potential, likely enough to run 100% E85 on the LNF. This is the part that we believe we've sorted out now. I'll be working on testing over the next few days, and a few people have offered to help test this out.
If it works out, we could be running 100% E85 in our LNFs within a matter of weeks.