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240sxguy
Joined: 08 Apr 2009
Posts: 10
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 Posted: Thu Apr 09, 2009 5:42 pm Post subject: |
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My apologies, I certainly need to be more clear. It is easy to forget you guys don't know me!
Drag racing 1/4 mile.
Evan |
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hotrod
Joined: 19 Apr 2005
Posts: 872
Location: Colorado
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| Posted: Thu Apr 09, 2009 8:02 pm Post subject: |
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| Quote: | Larry, this is the kind of info that I was wondering about. I do run high boost on the street @ 25ish PSI. What I was really wondering I suppose.. was if the minor changes (10%) in E85 was enough to wreak havoc on my tune and car..
Sounds like it really isn't. |
It also depends on two specific issues:
How anal you are ? --- some "tuners" are super anal and if they get max power on the dyno at Lambda 0.756 they want to get exactly that lambda all the time. If they had a clue about how cars respond to variations in fuel air mixture, in real terms on the street you can't tell the difference between 0.74 and 0.76. On the drag strip ---- Yes maybe you could see the difference but the power curve compared to fuel air mixture is very smooth and round at the top of the hump (assuming you have a sensible tune), and in that area rather large changes in AFR make relatively little difference in power.
At 0.82 my car is sluggish under WOT but from about 0.76 - 0.72 I cannot see any meaningful difference in performance. So at high boost I use the safe end of that range and tune for 0.72-0.74 and at moderate boost I let the numbers drift down below 0.76.
The second question is how close to the edge do you tune (which applies partially to my above comments). Some tuners set the car up with no safety cushion in the tune. If they have a problem they kill the engine immediately. If they tune for the safe end of max power rich mixtures and the safe end of timing at MBT (minimum best torque timing) they have a relatively large safety cushion. The old NACA when tuning supercharged fighter plane engines did all their testing at MBT defined as the minimum timing that would show a 1% loss in power from the max power they could achieve. That means on a 1200 hp engine they were willing to give up 12 hp to keep the engine alive under combat emergency conditions. On a typical street car making 500 hp you give up a whopping 5 hp to tune that way. You will never see the difference in street performance by giving up that 5 hp as you try to merge into traffic.
At the drag strip it might cost you a thousandth of a second or two on your ET in exchange for not having to buy a new engine if you have some hiccup in fuel delivery or over heat a bit during a run.
Larry |
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240sxguy
Joined: 08 Apr 2009
Posts: 10
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| Posted: Thu Apr 09, 2009 9:21 pm Post subject: |
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Larry I am not a ragged edge tuner. As far as timing, I tend to add timing until power stops then back it off a degree or two (depending on how much HP I am giving up). I have never had issues with knock even on pumpgas with this engine. I do have knock sensors, although they won't pull timing automatically.
I am also willing to modify my tune "on the fly" if I need to pull timing or pull/add a bit of fuel. This can be done at the track to achieve a reasonable a/f ratio with my laptop.
I will gladly give up .05 in the quarter not to poke holes in a pretty costly lower end.
I know with the right tune I can make a reliable 500whp, although my turbo may cork me up at that point. There is a possibility I may put my car in the hands of a more experienced E85 tuner. Problem is, I don't really trust anyone around here and the nearest shop I do trust is 225/hr for dyno tuning (AMS).
Thanks!
Evan |
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newalky
Joined: 30 Sep 2008
Posts: 84
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| Posted: Thu Apr 09, 2009 9:28 pm Post subject: |
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| Alcohol wrote: | Evan- you are just south of me. Looks like you have a handle on it- E70 winter, E76-78 spring, and of course E85 summer. Right now, being a changover month you will find E70-E78 out there.
Will the station you buy from provide you the exact blend info on the date you want to pick it up. (for instance- I know right now what % is in each store's tank).
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Alcohol, I asked 2 of the stations that sell e85 near me. One of them I asked today. She said she doesn't know, even though they were just filled.
I asked her if the drop sheets tell her how many gals. of ethanol and how many of unleaded gas? She said no.
So I race @ Union Grove WI. Are you close to there? I could bring a drum and fill it. Plus I would feel better buying from you than a gas station that doesn't care about racers!! Thanks, newalky |
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Alcohol
Joined: 17 Apr 2007
Posts: 634
Location: Central Wisconsin
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| Posted: Thu Apr 09, 2009 11:18 pm Post subject: |
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I am a long way from Union Grove newalky. Nearest I have to you is a full hour north of Milwaukee. Mine are all over the board for blends right now-from E70 to E76.7 since the blend switchover just began. I do maintain an accurate blend calc for each site though that gets updated with each load.
I have blender pumps that someday I hope to receive in straight E98 (like when I started) and hope that at a few limited sites the state would allow me to have 1 hose dedicated for either summer E85 year round or E98 year round- just for racing or future cars w/fuel cells or dedicated high ethanol. This will not happen for a while but we can dream eh?. Biggest problem will be keeping grandma Jones from putting it in her car in the middle of winter  Not everybody reads 
What is nice about a blender pump is that the blend option allows such flexibility -any % ethanol in 1% increments can be preprogrammed for sale. Thus if I had NL gas in one tank and E98 in another one could have as an example an E0 in one hose, E20 in another, E98 in another, or other such combos. |
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newalky
Joined: 30 Sep 2008
Posts: 84
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| Posted: Fri Apr 10, 2009 8:31 pm Post subject: |
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Alcohol thanks for your reply. Most of the stations that carry e85 in my area (northern IL) are Gas City. Any suggestions on how to get blend info from them? It seems like I always talk to a clerk who knows nothing about the mechanics of the station, but they can make sandwiches!
When will my area get 78% or higher? Thanks, newalky  |
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Alcohol
Joined: 17 Apr 2007
Posts: 634
Location: Central Wisconsin
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| Posted: Fri Apr 10, 2009 9:01 pm Post subject: |
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Try emailing them at HQ and let's see if corporate is better than store clerks; http://www.gascity.net/contact.asp
You will of course need to make it easy for them by telling them how you love them and which store you go to 
IL should be on the same schedule as WI so I would assume they are getting it (E78) now as they restock. Keep in mind though that the load they get will be dumped on top of 700-3000 gallons so first load final tank blend will only be E74-E77 since they are likely starting at E70. |
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newalky
Joined: 30 Sep 2008
Posts: 84
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| Posted: Sun Apr 12, 2009 9:31 am Post subject: |
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| Thanks again. I will come up with a GOOD letter and try that. newalky |
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