importwarrior Posted May 24, 2013 Report Share Posted May 24, 2013 (edited) simple is the 10 Degree slop in the timing chain really that much slop? so what do you prefer and why? Mighty Max Dizzy or Crank Trigger? pros Cons Edited May 24, 2013 by importwarrior Link to comment Share on other sites More sharing options...
Funky Phil Posted May 24, 2013 Report Share Posted May 24, 2013 Stock Dist with caravan module. because it works just fine and parts can be found at local auto stores. Link to comment Share on other sites More sharing options...
StarquestRescue Posted May 24, 2013 Report Share Posted May 24, 2013 simple is the 10 Degree slop in the timing chain really that much slop Where did you come up with that number? Link to comment Share on other sites More sharing options...
psu_Crash Posted May 24, 2013 Report Share Posted May 24, 2013 That number was brought up by another member. I'm sure there is some amount of error with the chain slop and how tightly the gears mesh but exactly how much likely depends on the specific engine.I have run both setups and the big advantage I see with the CAS is the ability to go full sequential fuel and spark. Assuming it's being used to send triggers to a standalone it is also less hardware to install than an EDIS. The whole reason I switched from a 36-1 wheel to the CAS was because with the new radiator the MK1 trigger wheel would hit the radiator fan shroud. Link to comment Share on other sites More sharing options...
importwarrior Posted May 25, 2013 Author Report Share Posted May 25, 2013 The 10 Degree was posted and stated by a few members. i was just wondering MPI guys thoughts on the triggertype they like and Why. Link to comment Share on other sites More sharing options...
StarquestRescue Posted May 25, 2013 Report Share Posted May 25, 2013 The 10 Degree was posted and stated by a few members. i was just wondering MPI guys thoughts on the triggertype they like and Why.Yea, i found the post. Button is a professional tuner i believe, but i am not buying 10*. Maybe he meant to type 1*. I could see greater accruesee from the crank though. Link to comment Share on other sites More sharing options...
tux Posted May 25, 2013 Report Share Posted May 25, 2013 magna cas. easily accessible from australia ebay Link to comment Share on other sites More sharing options...
psu_Crash Posted May 25, 2013 Report Share Posted May 25, 2013 magna cas. easily accessible from australia ebay Show me Link to comment Share on other sites More sharing options...
Funky Phil Posted May 25, 2013 Report Share Posted May 25, 2013 when your loading the engine theres not going to be a 10deg discrepancy. If so, that engine is VERY worn. Link to comment Share on other sites More sharing options...
polarisman14 Posted May 25, 2013 Report Share Posted May 25, 2013 I'm talking out my behind because I have no experience with this, but a friend getting ready to run MS on his porsche 944 says a lot of members don't like the crank trigger option as the sensor can actually get less sensitive/dirty with time. I'm running the modded/locked stock dizzy with CR125 module and it works great. My system does have some electrical interference but MS has tunable noise filters built in that Scott has manipulated to give a good quality tune. Link to comment Share on other sites More sharing options...
scott87star Posted May 25, 2013 Report Share Posted May 25, 2013 While I'm sure there is a bit of slop in a chain drive its manageable, look what Ford did with its 427 "cammer" motor, that chain has to be 3X as long as a G54b. No, its more to do with the resolving power of multiple data points, more times the computer knows where the crankshaft is. In the CR125 case or the stock VR pickup the ECU knows where the crankshaft is every time it fires, or twice in once crankshaft rotation which is once per 180 degrees. The electronics is working with a crank angle of about 70 degrees, meaning it sees a signal to fire and 70 crank degrees later after its computed when it should fire based on the current rpm and map from the ignition table it does fire. At a constant crankshaft speed that all works just fine but if the crank is accelerating or decelerating its not going to be as accurate. During acceleration its lagging a bit so you're not getting all the advance you've assigned (slightly retarded timing) and under deceleration you're getting more (slightly advanced), how much would require some testing and isn't worth the effort because you can go to a trigger wheel of 12, 24, 36 or even 60 teeth per crankshaft revolution. Now the computer knows where the crank is every 30, 15, 10 or 6 degrees of crank rotation instead of 180 degrees. It shouldn't take a rocket scientist to realize the location of the next fire event is going to be a lot more accurate or true to the timing table. Phil has a lot of success running with 180 crank degree resolution, just go look at the videos or even better meet him at the track and see what the simple, reliable approach can do. I have noticed in my own MPI/CAS equipped car that the upgraded wheels available give a smoother running engine, probably the equivalent of going from the stock coil to a CDI multi-strike, probably not worth running out and replacing your CR125 setup but for a future build you might consider it. DIYautotune sells a 12 -1, +1 wheel (that I've tried) for $25 that takes about 2 minutes to install in a CAS that works like a 12 -1 crank trigger with cam signal. One of megasquirts confusing issues is that the MS1 processor decodes the wheel inputs differently than MS2 and 3 so I would not recommend doing a wheel upgrade (crank or cam) and a new engine build at the same time. I think I wore my starter out getting it sorted. Note that the OEM's have backed away from 60+ position wheels as its too much and limits rpm. Not in the operating range of a G54 but if you dig around in the MS forums you can find posts that show the limits. Link to comment Share on other sites More sharing options...
psu_Crash Posted May 25, 2013 Report Share Posted May 25, 2013 Scott maybe you can give some pointers on MS2 setup with a 24/1 CAS wheel? No problem with MS1 but for the ECU upgrade I haven't figured it out yet so the 4/1 wheel is still installed. I know going to the hi res wheel on ms1 made a noticable improvement in idle quality Link to comment Share on other sites More sharing options...
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