thorne Posted January 24, 2008 Report Share Posted January 24, 2008 I've been going over this in my head and I'm not sure if its a good idea or not. I know I can tune the car to not knock on 87 octane. But I don't know if my gas millage would go down by removing so much boost/timing. I was just thinking of my money I spend on gas a month and figured If I could get better milage out of cheaper gas why not. Quote Link to comment Share on other sites More sharing options...
Dr. Apex Posted January 24, 2008 Report Share Posted January 24, 2008 I guess it's possible but I just don't see your mileage getting any better and if your wrong the consequences could be bad if your not careful with it. Just buy a beater that will run whatever so you don't have to event bother with it. Quote Link to comment Share on other sites More sharing options...
thorne Posted January 24, 2008 Author Report Share Posted January 24, 2008 I plan on getting a beater, But the transmission install took allot out of the thorn funds Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 If you were to tune the car on 87 octane but keep the same a/f numbers that you currently use, you would see a decrease in horsepower and you wouldn't gain any gas mileage. To get better gas mileage, you would want to tune your cruising map to an a/f ratio around 15.7:1. You would be able to use any octane gas and see better fule mileage results. Quote Link to comment Share on other sites More sharing options...
thorne Posted January 24, 2008 Author Report Share Posted January 24, 2008 If you were to tune the car on 87 octane but keep the same a/f numbers that you currently use, you would see a decrease in horsepower and you wouldn't gain any gas mileage. To get better gas mileage, you would want to tune your cruising map to an a/f ratio around 15.7:1. You would be able to use any octane gas and see better fule mileage results. The car sits at 14.7 at cruise as it is. I guesse it was a silly idea. ohhhhhh welll. I would prolly get pissed off at it anyways not having the power. Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 Right, you want it to run above stoichiometric for better fuel economy. Quote Link to comment Share on other sites More sharing options...
rl Posted January 24, 2008 Report Share Posted January 24, 2008 Right, you want it to run above stoichiometric for better fuel economy. And that will lead to terrific driveability too! lol Quote Link to comment Share on other sites More sharing options...
thorne Posted January 24, 2008 Author Report Share Posted January 24, 2008 It seems like to much trouble spieaclly since I can't change maps on the fly. Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 You probably know this but I just wanted to add something. When the oem's run 14.7 at cruise, it's because they only care about emissions and not fuel economy. You can run it a little leaner and will see a gain in fuel economy and still be safe. Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 RL, I had no problems tuning for 15:7:1 on a dyno and there was no driveability issues at all. It was tuned in real-time though. Quote Link to comment Share on other sites More sharing options...
Nate1647545505 Posted January 24, 2008 Report Share Posted January 24, 2008 RL, I had no problems tuning for 15:7:1 on a dyno and there was no driveability issues at all. It was tuned in real-time though. The difference in BSFC between 15.7 and 14.6/14.7:1 is roughly 4-5%, which is a very small amount considering the torque output drop is roughly triple that. At this point you're going to need more torque - throttle, to maintain the speed of the vehicle against any drag. 15.4:1 is where most engine's hit peak thermal efficiency, and usually is cited as the outer most air/fuel boundry before torque drops off like it was paulie shore. Tyrone - did you do the work on loaded dyno? I'm assuming since it was done in real time the answer is yes, in which case you should have seen some torque dips durning tip in with such a lean A/F ratio. I think that's what RL was trying to get at. Quote Link to comment Share on other sites More sharing options...
thorne Posted January 24, 2008 Author Report Share Posted January 24, 2008 Speaking of Tip in. I've yet to figure out on my subby why when I first get on it on the dyno or street it goes rich then comes to my AFR's I specified shit pisses me off Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 Nate, you are correct. We were playing around and tuning for fuel efficiency only at cruise and light loads. Quote Link to comment Share on other sites More sharing options...
Nate1647545505 Posted January 24, 2008 Report Share Posted January 24, 2008 Speaking of Tip in. I've yet to figure out on my subby why when I first get on it on the dyno or street it goes rich then comes to my AFR's I specified shit pisses me off I'm not familiar with Subaru's controls but generally speaking regarding engine control strategy: non steady state fueling is mainly influenced by acceleration enrichment or dynamic airflow calculation parameters. Predicting airflow during transitions can utilize simple modifiers or complicated system response curves. Quote Link to comment Share on other sites More sharing options...
rl Posted January 24, 2008 Report Share Posted January 24, 2008 Tyrone - did you do the work on loaded dyno? I'm assuming since it was done in real time the answer is yes, in which case you should have seen some torque dips durning tip in with such a lean A/F ratio. I think that's what RL was trying to get at. Exactly. You can see lean misfires in that range, heck mod motor fords will begin to lean misfire around 15.5:1, some motors wont until they are leaner, but you typically will never command anything that lean. You won't end up with perfect driveability, and depending on the control system you might not be able to accurately command that AF in closed loop. Quote Link to comment Share on other sites More sharing options...
Nate1647545505 Posted January 24, 2008 Report Share Posted January 24, 2008 Exactly. You can see lean misfires in that range, heck mod motor fords will begin to lean misfire around 15.5:1, some motors wont until they are leaner, but you typically will never command anything that lean. You won't end up with perfect driveability, and depending on the control system you might not be able to accurately command that AF in closed loop. Hey Rob - dumb question - what kind of HP can you get out of the Ford EDIS systems on the V8's without any additions? Quote Link to comment Share on other sites More sharing options...
tyrone Posted January 24, 2008 Report Share Posted January 24, 2008 I see your point and I guess I shouldn't have specified 15.7:1. I should have said lean it out more at cruise. I did it using a Motec and Autronic stand-alone on the class cars, which were basically unmodified 4 cyl n/a vehicles. Quote Link to comment Share on other sites More sharing options...
Flybye Posted January 24, 2008 Report Share Posted January 24, 2008 premium really isnt that much more... and getting slightly better gas mileage will make up for it in the long run. i dont see a reason why the switch would be justifiable Quote Link to comment Share on other sites More sharing options...
rl Posted January 24, 2008 Report Share Posted January 24, 2008 Hey Rob - dumb question - what kind of HP can you get out of the Ford EDIS systems on the V8's without any additions? 500-600rwhp. The gaps on the plugs end up being pretty tight though (like .020). They might even go higher than that. I have a full EDIS 8 setup here for a 302 minus the coils if you need one! You can have it dirt cheap. Quote Link to comment Share on other sites More sharing options...
thorne Posted January 24, 2008 Author Report Share Posted January 24, 2008 I'm curious on how well I my tune on the wrx would stand up to a protuner. Would any protuner be willing to help with my expeirment. I'm really curious but not enough to pay a ton for a couple hp. Quote Link to comment Share on other sites More sharing options...
Nate1647545505 Posted January 24, 2008 Report Share Posted January 24, 2008 I'm curious on how well I my tune on the wrx would stand up to a protuner. Would any protuner be willing to help with my expeirment. I'm really curious but not enough to pay a ton for a couple hp. I think you'll see more "pro" tuners` portfolios shine in the stand-alone area. Most of OEM calibration revolves around the availabilty of options to calibrate versus the resources needed to calibrate them. If you have a control system that is popular and widely supported like the LSx or Mod Motors, you see the problem less, but your many times stuck within OEM maximums. GM is making a push to use a standardized platform and the way they've done so is ingenious. I imagine the other domestics along with competing foreign platforms are doing the same. Quote Link to comment Share on other sites More sharing options...
Nate1647545505 Posted January 24, 2008 Report Share Posted January 24, 2008 500-600rwhp. The gaps on the plugs end up being pretty tight though (like .020). They might even go higher than that. I have a full EDIS 8 setup here for a 302 minus the coils if you need one! You can have it dirt cheap. I appreciate the offer - mainly had read varying numbers, saw you post and it jogged the memory to find some clarity. The GM crew would crucify me. Quote Link to comment Share on other sites More sharing options...
Patrick Posted January 24, 2008 Report Share Posted January 24, 2008 I know that the Omni was actually designed to run on 87, recommended in the owner's manual and on the gas flap. Even though it was a turbo, I saw very little difference in milage or anything of the sort from running cheap 87 to Sunoco 94. Quote Link to comment Share on other sites More sharing options...
Draco-REX Posted January 25, 2008 Report Share Posted January 25, 2008 I know that the Omni was actually designed to run on 87, recommended in the owner's manual and on the gas flap. Even though it was a turbo, I saw very little difference in milage or anything of the sort from running cheap 87 to Sunoco 94. Well if it was tuned for 87, you probably won't see much gain going to 94 without a retune. Whereas if you're tuned for 94 and go with 87 without a return you'll see a big difference (if the engine doens't knock itself to pieces.) Thorne, have you thought of a 0% WGDC map to flash-in for when you won't be flogging the WRX? If anything, it'll help keep your lead foot from stepping on your wallet. Quote Link to comment Share on other sites More sharing options...
ridenred27 Posted January 25, 2008 Report Share Posted January 25, 2008 I appreciate the offer - mainly had read varying numbers, saw you post and it jogged the memory to find some clarity. The GM crew would crucify me. but the ford crew will welcome you with open arms Quote Link to comment Share on other sites More sharing options...
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