Im curious what everyone's technique is for dealing with two fuels of different stoich value whether it be meth injection or a mix of 93 and race gas. Thanks
Im curious what everyone's technique is for dealing with two fuels of different stoich value whether it be meth injection or a mix of 93 and race gas. Thanks
Joe
2006 M6 GTO
APS TT
10.76@131
"The goal of tuning is for the tune to run well enough you dont need any corrective mechanisms"
Since the meth only comes on under boost on my application I ensure my stoich value is richer under boost. I shoot for 10.5 with meth. I use my P.E. table for this since I'm usually within these parameters when in boost. I haven't tuned with a race fuel yet but I'm assuming I'll be doing things the same way. Unless I plan on daily driving with race fuel then it will be a mute point since I won't be able to afford driving the car lol.
Subscribed to this thread in case im screwed up....
Last edited by Ironmancan; 01-16-2010 at 07:54 PM.
06 Twin Turbo GTO
you have to run two different tunes for two different fuels...
at normal driving...under closed loop operation...it really wont matter...your car will always correct itself to a stoic burn ratio....the o2's in your car will always report stoic at the same voltage regardless of fuel used..it doesnt care about AFR..it cares about Lambda=1.0
but you have to run different tunes for the open loop operation...no way wround it...in open loop you are telling the PCM to command a certain amount of fuel delivery...and differnt fuels = different mass = different AFR for WOT needs
while in closed loop your car will correct for e85..at WOT..is gonna try to put in a value based on the MAF/VE tables and a multiplier.. which if left alone could equal 13.0 on gasoline...and wont even be close to enough for e85 WOT.
you can see how somebody who runs a gas tune would be extremely lean at WOT for E85...or somebody with an e85 tune would be extremely rich on Gasoline...
so...as stated earlier...
different fuels = different tunes...no way around it
-Scott -
I should have been a little more specific. I meant a mix of two fuels at the same time. I guess I mean what AFR should you shoot for if you are running pump gas with meth injection or a mix of 93 and C16.
Joe
2006 M6 GTO
APS TT
10.76@131
"The goal of tuning is for the tune to run well enough you dont need any corrective mechanisms"
that gets even more tricky....
you need to find out the stoic values of both fuels..
then you can do some math to figure out what the blended stoic value should be...
a safe bet to start at would then be an AFR value that is approximately .85 lambda
if you had a 50/50 blend of gasoline and e85 you would have a 14.63 for gas and 9.65 for e85
14.63+9.65 = 24.28
24.28/2 = 12.14 for stoic
12.14 x .85 = 10.319 for .85 lambda
that would be the starting point for me if that was the case...
if you dont know your exact ratio of the mix...then start with the one that has a lower stoic AFR and tune for that...then you can always lean it out a little at a time and check knock, exhaust temps, and horsepower/torque gains to figure out if its still safe or not
-Scott -
and I used e85 as the example becasue I dont know what c16 stoic is and didnt feel like researching to answer the question that I could just use a different already known example for.
-Scott -
Bader Norris
MEP Tuned
Telephone: +965-55446651
Email: [email protected]
With figuring for meth injection you should call the company and ask them for the actually flow rattings of the nozzles. Most are rated at 100 psi with a 1/2" id feed line. But its very common for people to not know about this.