MS master minds needed
#2
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,072
Total Cats: 6,625
I'm not all that familiar with the SR20 engine. Is it one of those weirdos that runs a CAS pattern giving something like 473 pulses per revolution on CKP?
#3
Jmscortina has been working on some nissan cas stuff for ms3, you might wanna read about that.
http://www.msextra.com/doc/ms3/nissancas.html
http://www.msextra.com/doc/ms3/nissancas.html
#7
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,072
Total Cats: 6,625
I finally found an image of one, and I'd have to say that the answer sounds like a yes.
Here's the stocker:
360 pulses per revolution on the main channel. Does that poor ECU have time to do anything other than receive primary interrupts?
I see two possible courses of action. You could knock out the majority of the holes in the outer ring, and apply a patch over others, to bring it down to a more reasonable pattern. Four evenly-spaced slots would suffice. Patch over the three small slots on the inner ring and you have a nice, easy 4+1 dual-output CAS.
Might now be much space available to do the patching, though. The optical elements have got to be pretty closely spaced if they're reliably reading that outer pattern.
Or you could do what some enterprising enthusiasts have done and get a new trigger plate. 24+1 seems to be popular, judging from a quick google search:
It would appear that AEM maketh one, too:
As does VEMS:
This is what it would sound like if If Leon Redbone Suffered a Major Head Injury.
Here's the stocker:
360 pulses per revolution on the main channel. Does that poor ECU have time to do anything other than receive primary interrupts?
I see two possible courses of action. You could knock out the majority of the holes in the outer ring, and apply a patch over others, to bring it down to a more reasonable pattern. Four evenly-spaced slots would suffice. Patch over the three small slots on the inner ring and you have a nice, easy 4+1 dual-output CAS.
Might now be much space available to do the patching, though. The optical elements have got to be pretty closely spaced if they're reliably reading that outer pattern.
Or you could do what some enterprising enthusiasts have done and get a new trigger plate. 24+1 seems to be popular, judging from a quick google search:
It would appear that AEM maketh one, too:
As does VEMS:
This is what it would sound like if If Leon Redbone Suffered a Major Head Injury.
#10
Thanks Joe I never knew how to use google, just amazing lol. Anyways I am liking this ideal you have here.
" You could knock out the majority of the holes in the outer ring, and apply a patch over others, to bring it down to a more reasonable pattern. Four evenly-spaced slots would suffice. Patch over the three small slots on the inner ring and you have a nice, easy 4+1 dual-output CAS." Joe
So all I do is make 4 good size slots that are the same size and evenly spaced to make it work?
" You could knock out the majority of the holes in the outer ring, and apply a patch over others, to bring it down to a more reasonable pattern. Four evenly-spaced slots would suffice. Patch over the three small slots on the inner ring and you have a nice, easy 4+1 dual-output CAS." Joe
So all I do is make 4 good size slots that are the same size and evenly spaced to make it work?
#12
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,072
Total Cats: 6,625
Actually, I just went to google images and typed in SR20 CAS. The first page was filled with images of non-standard CAS wheels, so I'm guessing this is a pretty common issue.
So all I do is make 4 good size slots that are the same size and evenly spaced to make it work?
The only other concern is how to go about blocking the slots. From the image miatamike203 posted, you can get a feel for how tight the fit is in the gap between the LED and the phototransisor. Anything that adds significant thickness to the disc may prevent it from passing through this channel. You're not going to just glob some JB-weld on there. Foil tape might work.
#15
After looking at the diy KA wright up it looks like the ka uses the same cas as the sr.
http://www.diyautotune.com/tech_arti...ssan_240sx.htm
http://www.diyautotune.com/tech_arti...ssan_240sx.htm
#17
Elite Member
iTrader: (2)
Join Date: May 2007
Location: Cromwell, Connecticut
Posts: 2,605
Total Cats: 16
Wish I saw this thread earlier...I probably could have helped you out.
You can change the wheels out pretty easily as people mentioned. We ran MS on my friends older VE30E Maxima that had a similar setup. The inner and outer holes use different sensors so you can do pretty much whatever you want when it comes to a trigger wheel.
I was about to start getting into MS right before I crashed my second 240.
You can change the wheels out pretty easily as people mentioned. We ran MS on my friends older VE30E Maxima that had a similar setup. The inner and outer holes use different sensors so you can do pretty much whatever you want when it comes to a trigger wheel.
I was about to start getting into MS right before I crashed my second 240.
#18
So after spending a good amount of time looking into running ms on my sr I decided to go with the crank trigger wheel. I do have a few questions tho. What is the best cps to use? Next is should I set up the ms2 for edis or dis? The sr uses 4 cops and an ignitor so I'm guessing dis for wastespark? Then I'll just need to figure out the needed coil dwell.
#19
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,072
Total Cats: 6,625
After looking at the diy KA wright up it looks like the ka uses the same cas as the sr.
http://www.diyautotune.com/tech_arti...ssan_240sx.htm
http://www.diyautotune.com/tech_arti...ssan_240sx.htm
Basically, they are saying to leave the wheel completely unmodified, ignore the outer ring completely, and trigger on the trailing edges of the inner ring (which are evenly spaced.)
In that configuration, the only thing that the ECU would be able to infer from any given pulse is that "something is ready to happen." In other words, it has no way of distinguishing one cylinder from another. Forget about wasted spark, you'd have to use a distributor.
Did these engine have both distributors AND cam-angle sensors?
You still would need to do the same routine on the inner ring, leaving only one hole intact, as you need some kind of reference to judge absolute cam position.
Well, actually I take that back. Since this wheel is turning at cam speed, you could do a "missing" tooth and still be able to run sequential, but I think it'd be better to run twin-signal. Less ambiguous.
So after spending a good amount of time looking into running ms on my sr I decided to go with the crank trigger wheel. I do have a few questions tho. What is the best cps to use? Next is should I set up the ms2 for edis or dis? The sr uses 4 cops and an ignitor so I'm guessing dis for wastespark? Then I'll just need to figure out the needed coil dwell.
A crankwheel, if properly done, is always superior. More precise, since even timing chains have some slop. If you go the crankwheel route, you will still need a 1-pulse-per-rev cam reference if you want to run full sequential. (You could still wire for semi-sequential fuel and wasted-spark ignition if you needed to, but the cam sensor will allow you to avoid this.)
Avoid EDIS. It will give your dog herpes.
The best CPS to use is the one that fits. Here is one example of a completely custom crankwheel setup: https://www.miataturbo.net/megasquirt-18/wheel-timing-success-last-20241/ (Other have done theirs differently. I pass no judgement here. I will add that on mine, it took quite a bit of fiddling to get it all just right.)