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timing curve

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90AWDTalon

20+ Year Contributor
877
3
Jan 5, 2003
Everett, Washington
I went to a dyno yesterday, didn't do any tuning just some baseline runs to find out where I'm at hp wise. Turns out they use the mustang dyno so I didn't meet that objective. But while I was there I spent most of the hour talking to the shop dyno tuner. He's not familiar with DSM eprom tuning but is very familiar with stand alone setups and they host the EFI 101 classes at his shop, so I trust what he was saying. I wanted to bounce these theories off you guys to see what you thought about trying them.

He said my fuel was good even though it showed rich on their a/f meter starting at about 11.8:1 and tapering down to 10.0:1, my WB matched the curve but read about 1.1:1 leaner. He said that because that was working very good on my motor I should leave it there. He said that the engine will let you know what the proper af ratio is, and that once you get there you wont gain more than a couple of hp messing with the af ratio. He said that during there EFI 101 classes they have a car that has the timing setup perfect and show that af changes make almost no difference in hp.

We talked about the timing curve alot, he said the timing should be lowest at peak torque, and should have a smooth curve inverse of the torque curve. and a similar curve before the torque peak but you have to take turbo spool into consideration in that area. I'm using the timing map that was provided with the extended map guide that Kyle Terry wrote up a while back. The timing curve on that map at the air flow area of the map I'm in is very smooth but starts very low an climbs quickly. At the air flow I'm at peak torque was 9* and 7000rpms was 19*. He said that I should be able to add quite a bit of timing at the torque peak, and then make a smooth curve from there.

Any one have any thoughts on this?

Heres some pics of the dyno chart and dyno trace for any one that is curious.

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I made some changes to the timing map, my current airflow is in the 3.00 to 3.38 g/rev portion of the map. I haven't burnt and tested this yet. Let me know what you guys think.

New map
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Old map
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I don't think you would want to much timing at peak torque as this is when there is the most pressure in the cylinders and the car is more prone to knock. Also the fact that you get peak torque fairly early I would think that 9 degree's is fine.

Although looking at some of my logs I have around 11 degree's timing in the 4k rpm range So I guess you could add a couple degree's.

Too bad you couldn't change this stuff on the dyno then we wouldn't need any of this theory BS :thumb:
 
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