Fuel Scalar and it's limits (Ethanol)?

[RSL]

I don't run ethanol, but it may come down to injectors for DI only at some point. Every time one hurdle is overcome, the next bottleneck pops up and will probably need injector tables and monitoring soon to work on them. Injectors are the final metering into the cylinders, pressure will just effect how much gets through for a given open size/time. When that maxes out, need larger size and/or more open time to increase fuel reaching cylinders.

If you want to shift weight off scalars, increasing base fuel calc should help and doing it indirectly through air calcs might be the only way right now. Depending exactly what the limiting factor is though, might not change much/anything except to alter ratio of calculated vs. trim/scalar. If that does open room on scalar for a bit more request, but injectors are already max/limited by stock parameters, it isn't going to help.

The scaling itself would be one to limit to not more than needed IMHO. It reduces calculated air (and matching fuel) when there's actually much more air (and fuel needed). Same correct fuel amount is needed for the real air, but trims are increased to make up the difference between what was calculated for (low on scaled) and how much there really is (higher). Lower loads on scale may also effect undefined tables that impact it.

 

[MoreBoost]

Just setting afr lower in the high load, high rpm range doesn't help? With trims being limited to -30%,+30%.

(Ah, now i see this is suggested above)

 

[RSL]

Ratio of fuel to air is one thing, volume or mass of fuel needed to achieve it is another and how it's controlled to achieve is another. What I was talking about above mostly was just shifting the balance off trims to calculated fuel, the same total fuel needed wouldn't change unless boost or fuel does.

Targeting leaner will obviously reduce fuel demand for a given amount of air, but wouldn't be a first choice if the ratio is already close to where it should be. Not sure how much headroom it could even potentially add. All things considered, seems like the short-term solution would be to drop to a more reasonable ethanol mixture so less volume is necessary or hold boost down to what you can actually supply fuel for safely. Maybe once HPFP tables get out and others start tuning full E85 DI only, there will be a better idea of what might help, but it will surely come down to injector control/expanding stock limitations to truly maximize delivery on a DI setup.

 

[Rob09msport]

Ratio of fuel to air is one thing, volume or mass of fuel needed to achieve it is another and how it's controlled to achieve is another. What I was talking about above mostly was just shifting the balance off trims to calculated fuel, the same total fuel needed wouldn't change unless boost or fuel does.

Targeting leaner will obviously reduce fuel demand for a given amount of air, but wouldn't be a first choice if the ratio is already close to where it should be. Not sure how much headroom it could even potentially add. All things considered, seems like the short-term solution would be to drop to a more reasonable ethanol mixture so less volume is necessary or hold boost down to what you can actually supply fuel for safely. Maybe once HPFP tables get out and others start tuning full E85 DI only, there will be a better idea of what might help, but it will surely come down to injector control/expanding stock limitations to truly maximize delivery on a DI setup.

The fact that vtt hit 800 di only tells me that injectors aren't issue. They are technically 2000cc according to a bmw engineer back in 2009.

 

[RSL]

The fact that vtt hit 800 di only tells me that injectors aren't issue. They are technically 2000cc according to a bmw engineer back in 2009.

I don't remember the setup, but pretty sure it wasn't on E100 or a stock head/cams. One of those vendors that no one seems to ever be able to get close to for numbers, so wouldn't exactly quote their max as an average benchmark.

I thought it was actually higher than that on max flow, but no idea what they're control/time limited to. I guess we'll have a better idea of what's possible when more mere mortals start running DI only on the OD pumps with high E85 and big turbos. No clue what @MoreBoost is running or what power level, sounds like he's out of volume on the E98 though.

 

[Rob09msport]

I thought Eric hale ran double shotgun at high numbers and my point was if double shotgun improved things than the helix single should have no prob. Multiple little have stated closer to 800 reliability of injectors tanks maybe it's from running 3500 psi I don't know but now that fuel inlet tables are open it should help. @jayoma I do believe the prob with injection window was actual piston location and that the injectors haven't been issue just the hpfp. Also stock head or whatever don't make difference for fuel side maybe very slight if increase efficiency a little.

 

[RSL]

For whp on DI as a metric, ported head/cams do matter, as does tune and fuel used. I was referring to head/cams on the output side, not how they effect fuel.

Not sure how Helix will stack against double shotgun, but we'll see. Increased rail pressure would increase flow through injectors at any given point.

I vaguely remember Jake saying something about the angle, but there are also high/low plunger positions and other things that might be of benefit for delivery without increasing windows.

 

[Chris@VargasTurboTech]

I started a thread about this but haven't had much feedback yet, so I figured I'd try bumping this one. Have you run into a situation where you run out of fuel scalar (maxed at 1.6) while all the fuel pumps have more room in them? Happens most often when pushing big power DI only on high concentrations of ethanol, and usually when running a hpfp overdrive upgrade.

There's a great example on a different forum of a dude complaining about his double shotgun not living up to the marketing because his fuel trims and scalar are maxed out at like 22psi on e98, all the while his HPFP was holding strong at 3000psi. He was assuming his injectors were maxed out, but I don't think that's the case. I think it's a tuning problem.

As it sounds like you may be alluding to, I have also noticed a scaled map really pushes fuel trims up (all else being equal), so I'm wondering if there are some workarounds to manipulate MAF calcs to bring those trims back down beyond the BRO table. I haven't noticed huge swings with torque tables or vanos but they do help some. I just feel like with the scaled map making such major changes to fuel trims (as much as 25-30% increase on same boost, same fuel, same scalar for the reduced load, etc) there has to be a way for us to easily move them around as we please.

Fuel scaler max is 2.01 not 1.6. You have a lot of room left even with the XDF available now.

 

[Chris@VargasTurboTech]

I thought Eric hale ran double shotgun at high numbers and my point was if double shotgun improved things than the helix single should have no prob. Multiple little have stated closer to 800 reliability of injectors tanks maybe it's from running 3500 psi I don't know but now that fuel inlet tables are open it should help. @jayoma I do believe the prob with injection window was actual piston location and that the injectors haven't been issue just the hpfp. Also stock head or whatever don't make difference for fuel side maybe very slight if increase efficiency a little.

The Helix will supply half as much fuel as a DB. A double barrel is a single pump on the belt which is being spun 3X, AND another pump in the stock location. On a DB system, the pump on the belt will provide as much fuel as a Helix, then you have another pump on top of it. Hence "Double" barrel

 

[iminhell1]

Fuel scaler max is 2.01 not 1.6. You have a lot of room left even with the XDF available now.

It's not setup that way. And no one ever told us we could up that value max ever.
... or what the repercussions are when upping max value limits.

 

[Chris@VargasTurboTech]

It's not setup that way. And no one ever told us we could up that value max ever.
... or what the repercussions are when upping max value limits.

? Huh. The XDF is not set in stone. Like all RPM breakpoints, etc work for everyone? Go in and play with stuff, no one told us we could raise the scalers. That doesn't mean we just left them at 1.6 without trying higher values. 2.01 is the limit currently. When we were making big power DI only like 3 years ago we ran scalers at 2.01 on the top end quite frequently. Not enough people are willing to just try stuff on this platform

 

[Jeffman]

? Huh. The XDF is not set in stone. Like all RPM breakpoints, etc work for everyone? Go in and play with stuff, no one told us we could raise the scalers. That doesn't mean we just left them at 1.6 without trying higher values. 2.01 is the limit currently. When we were making big power DI only like 3 years ago we ran scalers at 2.01 on the top end quite frequently. Not enough people are willing to just try stuff on this platform

Thanks. This is useful to know. I also thought Fuel scalars were also limited to 1.60. Now I know how to adjust them higher.

I just learned something.

 

[V8bait]

? Huh. The XDF is not set in stone. Like all RPM breakpoints, etc work for everyone? Go in and play with stuff, no one told us we could raise the scalers. That doesn't mean we just left them at 1.6 without trying higher values. 2.01 is the limit currently. When we were making big power DI only like 3 years ago we ran scalers at 2.01 on the top end quite frequently. Not enough people are willing to just try stuff on this platform

The only limits in any of the tables are the hex limits and any logic caps. The xdf min and mix may reflect this or they may just be somebody guessing at what you should need. I've said this so many times back in the day I stopped caring to repeat myself.

 

[Tiron]

Looking at the XDF for IEJ0S, the min is 0.0 and the max is 2.006 for the actual hex. I bet anyone that wants to could right click on their scalar table and choose Edit Parameter XDF Info > Uncheck boxes for Use Low Range and Use High Range just like Chris@VTT is doing (or change the ranges).

XDF says its a 2 byte value (which has a range of 0-65535), and the conversion is (scalar = raw value / 32667).

 

[carabuser]

Is this a DIY tune? Scaled? What torque index array/torque limiter 3? You can tank rail pressure on perfectly good pumps/injectors/O2s even on pump gas if settings don't jive. Ask me how I know lol

Calculated air mass matters for fueling and revving in park isn't the same as driving with boost as far as that goes. Depending what other tables look like, a simple change in VANOS may show improvement in the pressure drop. A quick test would be to retard the intake cam (make the values larger) a few degrees at the usual load you see 3500-3750rpm and see if rail pressure picks up. Hopefully, a few degrees on the cam isn't enough to throw wrench in works for timing, etc.

What impact did you find from changing the torque index array/torque limiter 3?

I've played around with that table quite a lot and still don't really understand what they both do! Settings them to 150 across the board seems to work but I've never understood why.

 

[RSL]

They are VE/relative filling type tables and, for sure, they effect MAF calcs and then anything that relies on MAF (fuel, boost control, torque management, etc.). They may also directly effect internal torque calcs separate from air, as their names imply.

If there's no problem, there's no problem and I wouldn't worry about it. It's not easy nailing down everything that gets hit, but not a fan of just maxing both out like is/was popular. I'll be starting a new tune soon and will try to test some theories with them.

 

[carabuser]

They are VE/relative filling type tables and, for sure, they effect MAF calcs and then anything that relies on MAF (fuel, boost control, torque management, etc.). They may also directly effect internal torque calcs separate from air, as their names imply.

If there's no problem, there's no problem and I wouldn't worry about it. It's not easy nailing down everything that gets hit, but not a fan of just maxing both out like is/was popular. I'll be starting a new tune soon and will try to test some theories with them.

I'm currently making changes to my map and struggling to get the boost target to play ball. I know that increasing the boost limit multiplier will give me a greater boost target but there's a limit to how high. My current boost limit is 18.5psi but my target won't get above 17.9. Should I be increasing or decreasing the Torque Max (Index Array) and Torque Limiter 3 (Unk Limits) values to increase target boost?

I have my boost request offset set to 90 for all cells for the moment as dropping it any lower doesn't seem to help target any higher.

 

[RSL]

I'm currently making changes to my map and struggling to get the boost target to play ball. I know that increasing the boost limit multiplier will give me a greater boost target but there's a limit to how high. My current boost limit is 18.5psi but my target won't get above 17.9. Should I be increasing or decreasing the Torque Max (Index Array) and Torque Limiter 3 (Unk Limits) values to increase target boost?

I have my boost request offset set to 90 for all cells for the moment as dropping it any lower doesn't seem to help target any higher.

Extremely low temps, high pressure or something? What are load target, actual load, boost mean? Maybe actuals/other settings aren't enough. I assume it's not scaled?

Raising them really high should increase target (and totally jack up boost control and other things), but if lowering BRO doesn't do anything with boost target, not sure array/limiter 3 will either. They really shouldn't need to be touched at all to hit boost ceiling with boost target regardless, seems like something else is going on.

 

[carabuser]

Extremely low temps, high pressure or something? What are load target, actual load, boost mean? Maybe actuals/other settings aren't enough. I assume it's not scaled?

Raising them really high should increase target (and totally jack up boost control and other things), but if lowering BRO doesn't do anything with boost target, not sure array/limiter 3 will either. They really shouldn't need to be touched at all to hit boost ceiling with boost target regardless, seems like something else is going on.

load target - 193
load actual - 187
boost mean - 17.3
boost target - 17.39
amb pressure - 14.6
iat - 64f

I'm going to play with torque limiter 3 and see how it effects things since my BLM is set to 3.0 there and my BRO is 90 and Torque max is set to 140..

 

[RSL]

Ah, limiter 3 (full load) should probably be roughly the same as or higher than index array. There's probably an inverse ratio happening holding down target.