I took the slant out tuning last night. Mostly I worked on timing. TheAF ratio is at about 12.5:1 under boost, which is good, but I am still getting into detonation under boost. I came back to the garage and took out timing in the boost area of the map. It is all now down to about 14 BTDC in boost. It was late by then, and I actually did not want to go back out and test it. So unfortunately don;t know how it is behaving now. The timing was all over the map in the boost area, so I got it smoother looking, and lower in general. There were areas in the map as high as 26. While these cells were not near what I would expect to be an operating area of the map, I still took them down to 16-14 range.

I would sure like to hear from anyone out there fooling with this. Maybe I should go read the threads on the Mega Squirt forum. It has been awhile since I was there, and likely can;t remember my password. But at least I could 'lurk' there for awhile. The thing is, these small bore engines seem kind of rare, at least in the popular literature, and I think need their own approach.

I have been thinking water meth injection for years, so maybe I should just do that. Also, I think I about to put a lower thermostat in, which might help as well. Anothersix has been preaching this for some time, so maybe I should give it a try.
Sam

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water injection will definately help out. 12.5 a/f under boost is borderline lean... 11.5 to 12.5 is generally considered ideal. I've read some of your other posts, but I'm not sure how much boost you're running. with lower boost levels you can generally get away with leaner A/F ratios since the charge isn't as hot. As for the timing, it's very difficult to predict since every engine is different... (I was actually hoping to find more answers than questions in this thread)

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1966 Dart GT
1968 F250
2004 Dodge SRT-4

I'm running 16 degrees of total timing and 20 psi of boost but I still have a mix of premium and 110 race gas. (the race gas is only $1.20) more than premium unleaded here so it's cheap insurance. Initially I started with 25 degrees and that was way to much...bad sounds came from the engine. My A/F was rich and as I increased boost at the dyno from 17 psi to 20 psi it settled from 10.6 to about 11.4. I was using a 60% meth mix and the dyno guy said to scrap the water and run straight meth (VP brand). I think there is more in the motor with timing but it's probably 1 degree at a time.

Thanks for the feedback. That is helpfull. Do you know your compression ratio?

Sam

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It's a stock motor....rated at 8.4:1 but prolly more like 7.5:1 to 8:1 knowing Chrysler. My 340 was rated 10.5 and actual was 9.3:1. I also checked a 1978 360 2 bbl motor. Not sure what it was rated but actual turned out to be 7.5:1 with 72cc heads

The math figured my motor to be 8.5:1 when I rebuilt it and measured everything. I think you are better off with the lower compression ratio. Your engine can handle more boost than mine at this point.

Sam

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