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Re: re: aftermarket speedo Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Wed, 30 Mar 2016 14:39:26 In Reply to: re: aftermarket speedo, Simon S, Wed, 30 Mar 2016 11:17:01 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Yes! An aftermarket speed will definitely auto-calibrate. *Not* a problem. However, I still need an output to the fuel injection and that's the hangup. I still need to convert VSS AC output to whatever the fuel injection expects, that 2458 pulse per kilometer square.
The Dakota converter will do sine to square, no problem, but I need to know what ratio to tell it. *Obviously* that ratio is 4x (or, .25x depending on how you look at it). I think it's fair to say we know that from the factory literature. ;)
All I'm trying to do right now is devise a bench test for the converter, so I am trying to discover how road speed via ring gear correlates to VSS rpm. Because I can drive the VSS, but I can't easily drive the ring gear. ;)
From all my reading, Trionic is based on LH parameters - it works on the same 2458 pulse per kilometer that LH does... and Motronic for that matter! Makes sense, because keeping the signal the same probably saved redesigning a lot of parts in the early '90s, and eased concurrently selling Motronic and Trionic powered cars in the same bodies.
The 48 pulse per wheel revolution is interesting because it blows everything up. :(
The Trionic 9000 came with 195/65-15 or 205/55-16, so that's a 24.98" or 24.88" nominal height, and a 78.44" or 78.12" circumference.
195/65-15 is 807.75 wheel rpm at 60mph
205/55-16 is 811.03 wheel rpm at 60mph
We should have 3965 pulses per minute at 60mph (rough km to mile conversion)
Buuuuut.... 807.75 wheel rpm * 48 pulses = 38736 pulses per mile.
Any chance that 48 pulses per wheel revolution is actually 4.8 pulses? That would be just about right. It would also be very close to the 4.75:1 gear ratio I'd previously calculated.
posted by 12.195.130...
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