Tuning progressive meth with a WBO2 and EGT

[jayzelazo]

I am switching from a non-progressive setup that had a lower pump volume, to a progressive setup with a much bigger flow capacity.

I'm also going to be using a ECU that allows the WBO2 to adjust the fuel curve to a target AFR.

The problem I foresee in tuning this setup is that i have no clue what the target AFR should be once meth gets added into the picture.

Wouldn't this require knowledge of exactly how much gas the injectors are injecting and how much meth the alkycontrol setup is injecting at each map site, and then calcute the percentage of meth in the mixture to calculate with the ideal AFR/lamda should be? This sounds complicated. I can calcute the amount of fuel by injector duty cycle and fuel pressure, but not sure how i would calcutate the amount of methanol.

This whole thing sounds like a nightmare for tuning. I could just target an EGT, but that seems counterintuitive given that I have the ability to target exact AFRs.

thanks

Jay

 

[idaho gn]

i think you may be asking a good question here as adding meth should effect the af ratio you want to tune to


Gasoline 14.7
LPG (Propane) 15.5
Methanol 6.4
Ethanol 9.0
CNG 17.2
Diesel 14.6

 

[Roc87]

In the sticky, Razor says the DFI should be targeted for 11.3 AFR with methanol.

 

[Razor]

Roc.. your good

If you spray too much alky, your AFR will drop into the 9's.. big deal.. then start pulling fuel and bring em up into the 11's. Watch your egt as you lean the motor out and monitor your knock activity if possible. Keep leaning out the fuel.. add more alky, etc.. Knock activity will make the EGT's climb.

The PAC kit as delivered is pretty aggressive past 20 PSI boost.. so it should help you in that aspect.

Start at a low boost and lean it out. Like 18 PSI. watch how much fuel your displacing in your VE maps.. add alky until fuel displaced is approx 25%. That is typically a great starting point. Some motors like 20 others like 40. Just depends how much boost your trying to run over what it can do on 93 by itself.

Case in point, my own car, factory presets on the PAC box, blue knob 3/4 way up.. I just pull fuel out of the FAST to get the target where I want it.

See under high boost you blow a lot of alky in.. the gas is just going for the ride

HTH

 

[Eric88T]

hmmm...you know I'm watching this one Julio.

 

[jayzelazo]

Targeting an AFR of 11.3 would only be valid if you burning about 80% gas and 20% methanol.

This may be the case in many instances, but not necessarlily so.

What if you were burning 50% meth and 50% gas? Then your AFR at 11.3 would be so lean your motor would last a second. If Stoich for meth is 6.4 and you were running 50% meth, you would need to target a AFR of about 9 or you would be too lean.

The way I see it, if you don't know the percentage of meth you are burning, targeting a set AFR is completely useless. Knock count and EGT would be better to target but that seems like a rudamentary way to tune, IMHO.

Jay

 

[jayzelazo]

If you spray too much alky, your AFR will drop into the 9's.. big deal.. then start pulling fuel and bring em up into the 11's. Watch your egt as you lean the motor out and monitor your knock activity if possible. Keep leaning out the fuel.. add more alky, etc.. Knock activity will make the EGT's climb.

Razor, you lost me here. If you spray too much meth (and I presume this means that your mixture is burning alot of meth) your AFR would drop becuase meth has a much lower stoich value. So as you spray more and more meth and then bring out less gas, shouldn't you be targeting a lower AFR?

If you sprayed in meth that dropped your AFR to 9, and then pulled even more fuel, wouldn't the AFR rise to 11 indicate that you are running very lean?

How do you know to target an AFR in the 11's? Is this based upon knowledge that you know the percentage of meth that is being burned in your mixture?

Jay

 

[Razor]

Jay, I understand your post. All I can tell you is how its been done on hundreds of dyno pulls. And my interactions with shops across the country. Not just one source.

Target a richer number like 11.3-11.5 and work from there. If power increases are negligible from leaning out the AFR, then keep it on the fatter number.

ECS does theyre SC tuneup in the 11.8-11.9 range on blown LS1's. The DSM guys I know will target from 11.9-12.4. On my personal car it picked up 27 at 11.3.

9.0:1.. no way. What can I say.. the knock sensors, and data on high HP motors supports this. Even on setups that are doing big nozzles.. it is what it is.

Just had an DSM do 591 to the wheels using an M10+M15 nozzle at 180 PSI.. we're upping it to twin 15's to get it over 600 to the wheels.. that will happen in a week or so.. thats a lot.. lot of volume.. tuned on an AEM, 35 PSI, big time fuel replacement.

HTH

PS.. Eric are we done yet :biggrin:

 

[Eric Stage I]

Your wideband O2 is measuring Lamba, not A/F. The A/F is simply an interpretation. The Lamba that produces the best results will be similar between methanol and gasoline, say in the .75-.80 area, which will be interpreted as about 11.0-11.7 on your wideband (if it is set up to interpret gasoline).

So, in short, tune to the same numbers you would have with gasoline only. As Razor said, mid 11's is good area to start with and tune from there.

Regards,
Eric

 

[Razor]

Dug up an old post..

http://forums.corvetteforum.com/showthread.php?t=1114779&forum_id=86

 

[jayzelazo]

Razor,

Last year i had a car setup running a very good tune with an AFR of 11.9 running straight 92 octane (no alchohol).

When I drove home, I had to run my local gas which is 10% ethanol blended. My AFR stayed the same, but I noticed way more knock and had to pull timing. Eventually I ended up with a broken ringland. Months of research and discussions with engineers from the US and australia confirmed that if you switch from straight gas to a 10% ethanol blend, your target AFR should decrease by 0.57 to be safe. I don't have much empirical data to back that uo, but I know that many of the local guys using 10% ethanol blended gas had the same problem and it was cured by lowering their target AFR.

Now since stoich of ethanol is much higher than stoich of methanol, I would assume that your target AFR running 10% of methanol should decrease even more. Running higher levels of meth should decrease it even more.

I'm not an engineer, I just have a very expensive forged/sleeved shortblock that I don't want to blow up again.

Jay

 

[jayzelazo]

Your wideband O2 is measuring Lamba, not A/F. The A/F is simply an interpretation. The Lamba that produces the best results will be similar between methanol and gasoline, say in the .75-.80 area, which will be interpreted as about 11.0-11.7 on your wideband (if it is set up to interpret gasoline).

So, in short, tune to the same numbers you would have with gasoline only. As Razor said, mid 11's is good area to start with and tune from there.

Regards,
Eric

Eric,

lambda is much closer, but the target of lamda is still not equivalent for all sources.

According to this source: http://www.engin.umd.umich.edu/rese...ports/REUReport5-EmissionsE0-E85-2004.doc.pdf

With gas, your target lamda should be 0.85 to 0.90 whereas your target lamda for straight ethanol would be 0.70 to 0.85.

So i agree that targeting lambda would be much better.

I now see how running a 9 AFR would be out to lunch if your gage is set up to read AFR for gasoline. That would be way too lean even if you were running straight meth.

Jay

 

[jayzelazo]

Razor,

How do you figure out what percentage of your burned mixture is meth vs. gas?

Jay

 

[Razor]

Easiest is if you have DFI, see what it runs INJ DC on race gas, then switch to alky.. run the same AFR.. and see how much was displaced.

Example.. on race gas injectors are 80% DC. On alky its 64%. Thats 20%.

Another way is to measure pressure on the system, take nozzle sizing in to account, and come up with a flow number based on that. Then get your injectors.. fuel pressure.. and see what DC theyre running at.. you'll have a flow number on those.

A lot of this is fudged, in other words most will typically shoot way more alky than needed, its safer this way. Worst case is the car noses over. Just like running an AFR thats in the 10's to start.. its way safer. Then start pulling fuel and watching performance.. typically I pull alky as the last resort.. and then little by little trim it while looking for signs of detonation. If you can run the car on the edge of knocking.. and keep tight AFR's.. it will make the most power. And what amount does your particular motor need... man if I new that.. :biggrin:

I hate not giving specific numbers to target and do, reason is every motor is different in its response to the injection.

I'll leave it like this, those with Buicks that have my system will note the kit is plug-n-play on settings on an 86/87. That is becuase after doing so many.. I can pretty much set them up before they ship.. where little fiddling is required.

Jay, when you start the tuning process.. drop me a call and i'll walk you through it. Posts on internet forums are not very dimensional..

HTH

 

[turbov6joe]

On my particular set up I run a target A/F ratio of 11.3:1-11.5:1, have the MSD 50's running around 25-26pph (approx 50% DC) and the static FP right at 41 psi. I have the alky turn on at approximatley 6-7 psi and the blue knob in the 2:30 position. I run 100% meth and Amocco 92 octane. I shoot for 1600-1700 EGT's and KR in the LOW single digits MAX. On my car EGT's in the lower 1600's makes it a tad lazy...that means less than 25 mph gain. When I run in the upper 1600's I've seen as high as 30.5 mph gain from the 1/8 to the 1/4. While at BG this year Julio had me try disconnecting my volt booster as his was messing with his FM system. My car didn't like it and I believe the reason is because Eric M. has tuned my chips around the booster. The times in my sig was with the booster, first pass off the trailer with a TE45a, 212-212, THDP, ported heads and Julio's alky kit....that's it! If my guess is right that should be around 500hp to the tire...not too shabby IMO.