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Originally Posted by articfriends
(Post 2857886)
I aimed for 14-1 to 14.7-1 from idle to 2000,from 2000-2800 I aimed for 13.5-1 give or take a little,from 3000-4200 I aimed for12.8-1 to 13-1 then I went to 12-1 anywhere above that when not in boost and 11.4-11.6 under boost,remember you might end up with a tank of gas with a bunch of ethanol in it so don't try to tune as lean as possible you will have no safety margin since you get no exhaust feedback/correction.
My son has been going to local college tech program for ase automotive training and they had a alchohol spectrometer tester,he took samples from every local gas station and there were some as high as 16-18% (speedway/admiral),I'm not sure how strictly they keep the mix at 10% BUT if the samples came up high obviously no one watches it real close,Smitty |
Originally Posted by blue thunder
(Post 2857972)
I believe I have read where ethanol has properties that prevent (better than straight fuel) detonation. That is if it is fresh and not full of water obviously. I have a place close by where I can get straight gas but I have been a little hesitant due to reading this. The sc engines have been running great on 93 oct ethanol e10..
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Originally Posted by Mr Gadgets
(Post 2857788)
Jeff,
I have a datalog file from my EFI.. It is always a tune in progress, but it should give you an idea of what to sneak up on. The motor is a 565" NA, with 65# injectors.. Have fun!! Tuning is always a great excersize for the brain. OSO wont let me upload an Xcell file.. send me your email and I can fwd it to you.. Dick |
I was having a problem with the tach signal from the MSD distributor and went to a crank trigger. The rpm that the ECU saw was jumping as much as 120rpm in 50ms.. It was affecting the pulse width, so I ran it rich to not melt things..
After that my pulse width settled down and started to lean it towards the 13.0 mark at the top.. mostly it looks like 12.8-13.0 at the higher rpms.. Pressurized motors need way more fuel to stop meltdown and make power.. Smitty knows how all that works. I am just headed in that direction, if I can get all these darn outdrives done first.. :) :) Dick |
Blowers motors should always be run a little richer.
I agree with what Artic friends says about mix ratio. My only change would be to see what the motor likes at the top end while in boost. 11.4-7 to 1 might be too rich. You must spend alot of time tuning on the water to get it right. If your motor is not tuned right, it will wash down the cylinders and kill the ring seal--been there done that or too lean and burn a hole in a piston. Been there too.... Best thing is to find a guy who is really good. And one who takes his time..... Smitty |
Originally Posted by Smitty
(Post 2858116)
Blowers motors should always be run a little richer.
I agree with what Artic friends says about mix ratio. My only change would be to see what the motor likes at the top end while in boost. 11.4-7 to 1 might be too rich. You must spend alot of time tuning on the water to get it right. If your motor is not tuned right, it will wash down the cylinders and kill the ring seal--been there done that or too lean and burn a hole in a piston. Been there too.... Best thing is to find a guy who is really good. And one who takes his time..... Smitty |
Originally Posted by Smitty
(Post 2858116)
Blowers motors should always be run a little richer.
I agree with what Artic friends says about mix ratio. My only change would be to see what the motor likes at the top end while in boost. 11.4-7 to 1 might be too rich. You must spend alot of time tuning on the water to get it right. If your motor is not tuned right, it will wash down the cylinders and kill the ring seal--been there done that or too lean and burn a hole in a piston. Been there too.... Best thing is to find a guy who is really good. And one who takes his time..... Smitty |
My engine is not supercharged NA with MPI, I can change my fuel map at any combination of RPM and MAP. So should I be looking for numbers more like MrGadgets is using. He also has a NA engine, but a bigger engine turning more RPM. I am going to prop for 5400 RPM. Also what timing are you guys running? I usually run 34 to 36 total and 12 at Idle with full timing in at 3000RPM. The timing is fully adjustable on the laptop.
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My timing is at 40 but we also have a very efficient combustion chamber including flat top pistons that allows 40 degrees timing with no detonation. We also raced offshore with this timing with 93-94 pump gas at 9.3-9.5 CR.
Jeff, I think your settings are good and also safe. Extra timing might make 6-10 HP at 6000 RPM+ vs. 5400 RPM. The best place to test is on the dyno with your exact combination. I just looked at some old dyno sheets. Our dyno testing at 5400 RPM showed +1 HP at 42 degrees vs. 40 degrees. This was done with race gas to be safe. For 1 HP, we raced at 40 degrees with pump gas. Can't find some the old test, but I remember +2 to 3 HP from 38 to 40. |
Originally Posted by BenPerfected
(Post 2858715)
My timing is at 40 but we also have a very efficient combustion chamber including flat top pistons that allows 40 degrees timing with no detonation. We also raced offshore with this timing with 93-94 pump gas at 9.3-9.5 CR.
Jeff, I think your settings are good and also safe. Extra timing might make 6-10 HP at 6000 RPM+ vs. 5400 RPM. The best place to test is on the dyno with your exact combination. I just looked at some old dyno sheets. Our dyno testing at 5400 RPM showed +1 HP at 42 degrees vs. 40 degrees. This was done with race gas to be safe. For 1 HP, we raced at 40 degrees with pump gas. Can't find some the old test, but I remember +2 to 3 HP from 38 to 40. |
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