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Proper LH 2.2, heavy duty Posted by Kevin K [Email]  (#374) [Profile/Gallery]
(more from Kevin K) on Tue, 7 Aug 2001 10:55:49
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The best control is a new stand alone ecu, but this will be over $1000, and requires significant skills to install. It does eliminate rev limit, and opens the door to significant cam upgrades.
Problem with oem ... since very small 21 lb/hr inj'rs are used, simple BSFC calc'ns will show that duty cycle must be near 90% at 160 hp and 5500 rpm (for comparison, dsm's use 45 lb/hr inj'rs for 200 hp). So, if target is 230 hp, and larger inj's are used, the oem maps will max out fuel delivery rate just above 160 hp point, and things progressively lean out from there up. This can be seen on aaron's recent dyno plot, showing a/f ratio.
The initial resistance adjustment at the amm is mostly for idle and low power, with little effect at high power, afaik. The rrfpr's and big inj'rs result in excess richness up thru the oem hp point, and again progressive lean-out above.
The logical solution is to select injectors to match power increase, and recalibrate the output of the amm accordingly. So for 230 hp, 230/160 x 21 = 30 lb/hr inj's minimum. Basic amm output must be reduced 30%, across the rpm range, for about same a/f ratios as in oem range.
Enter signal conditioners, like ARC1(2), Apexi Super afc, and the HKS super AFR. The HKS looks best, since it can trim independent rpm steps, and is universally applicable ... should be Saab friendly, and is a reasonable $330 or so. You can tweak signal +/- 50% at each rpm segment independently, to really dial it in on a dyno, or even using simple a/f meter on the road.
Not sure about the later 2.4 LH systems that are adaptive, but may work there too.
posted by 52.128....
, Tue, 7 Aug 2001 10:55:49 <-- Viewing This Message, Wed, 8 Aug 2001 16:25:51, Tue, 7 Aug 2001 20:35:20, Tue, 7 Aug 2001 11:52:30
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