Mega Squirt DIY KIT
11-21-2009, 03:22 AM
#61
Race Director
I almost want to cry now... has been 12 or so years since I had a uban...
Now are they authentic, or US rolled, re-pat baco?
Best weekend I have had was spent in a hot tub floating beers in a cooler smoking authentic ubans... while some "hired help" was laying tile on the patio and grill deck... those were the days!
Now are they authentic, or US rolled, re-pat baco?
Best weekend I have had was spent in a hot tub floating beers in a cooler smoking authentic ubans... while some "hired help" was laying tile on the patio and grill deck... those were the days!
Tomorrow it is figure 8 burnouts
11-21-2009, 05:18 AM
#62
Addict
Rennlist Member
Rennlist Member
:MS itself will use 36-1 or 60-2 or 24-1 or whatever, as long as the number can be divided by the cylinder count and isnt excessive. Then it will direct fire the coil(s). But MS + EDIS means only 36-1 wheels, as the EDIS handles the crank sensing.
Chris's mount is excellent. There is also a source for 36-1 wheels made to fit on 944 cranks http://goingsuperfast.com/Trigger-wheels.html
11-21-2009, 05:20 AM
#63
Addict
Rennlist Member
Rennlist Member
Just to ask a basic question in context, why do all the various trigger setups make such a difference to each other? What's so wrong with the stock setup? Does it break, is it imprecise? My assumption is that in whatever trigger you use, it turns a revolution and is measured via a sensor. Whether there are 132 or 32 teeth etc, I assume that there is only one, or two trigger points per revolution and at 7000rpm how much do the various choices differ?
What about the difference between a crank and cam trigger? Again, it's just revolutions, no?
Apologies to those who are all over this stuff, but I'm sure that the majority could learn a thing or two.
Oh, and CP, Stop doing friggen' burnouts!! You've only just got this thing back after a nightmare run. Let the car do what it's designed for mate.
What about the difference between a crank and cam trigger? Again, it's just revolutions, no?
Apologies to those who are all over this stuff, but I'm sure that the majority could learn a thing or two.
Oh, and CP, Stop doing friggen' burnouts!! You've only just got this thing back after a nightmare run. Let the car do what it's designed for mate.
11-21-2009, 12:02 PM
#64
Stogies and beer at the shop was last night, and it was a cubano, brought home from a recent cruise with my wife to the Caribbean. Just gotta make sure you buy from a store down there, and not from the guy on the corner trying to sell you a box for $3/stick, those are the fakes.
On the wheel decoding question above, there are many ways an EMS can use a trigger wheel, crank mounted or cam mounted, to trigger an EMS. There are pros and cons to many of them. I probably won't get everything here but I'll dive in and try to hit a bunch of it and hopefully answer your questions-
While the EMS 'can' trigger at just one or two points on the wheel (usually in reference to a missing tooth if it's setup this way) this greatly reduces the resolution, or the accuracy at which the EMS tracks the crankshaft position. The more points the EMS updates crank position at, or triggers, the more accurately it can track crank position. At the same time, the more it has to track, the more processing power it takes to keep up with it all. 36-1 is good, 60-2 is great, more than that, well, you're just showing off
.
Ideally a crank mounted trigger wheel is used to indicate crank position. There will be far less (almost zero) 'jitter' introduced into the system from the timing belt and camshaft in this situation. If you've ever put a timing light on a distributor based vehicle that has the trigger mechanism inside the dizzy, and put a light on a different crank triggered vehicle, you'll see a drastic difference. The light on the dizzy vehicle will seem to jump around, with the timing bouncing as much as a degree or more even at idle. The light on the crank triggered vehicle will be rock solid, the wheel may not even look like it's moving. That accuracy is a very good thing, as what you're seeing at idle happens at high rpm too, so if you want your timing to be perfectly what you tune it to be, and jitter free, crank trigger it is.
If you have a crank trigger wheel, and only a crank trigger wheel, assuming a missing tooth, you have enough information to trigger an EMS for distributor use, or for wasted spark ignition. Similarly you have enough information to fire the injectors in batch or bank-to-bank. If you want sequential injection, and sequential coil-per-plug or coil-on-plug ignition, you need something more, you need to know the exact time that cylinder #1 comes to TDC. That's where a cam wheel working alongside your crank trigger comes into play. That cam wheel in it's simplest form will have one tooth (or trigger, it could be a hall or optical setup, I'm using tooth sortof generically here) and that tooth will indicate TDC of cylinder #1. Since the cam only turns once per two revolutions of the motor, this will only come around to the sensor similarly once per two revs, and will indicate cyl1 TDC to the computer. With this info the EMS can sequentially fire the injectors and the coils in the proper order.
One more note-- this crank wheel and cam wheel can both be shoved inside a single housing and mounted on the cam, and this is common practice for many OEMs. Sometimes inside the base of distributors, and sometimes inside a separate CAS housing that triggers the ECU that then fires a wasted spark or COP ignition system. This works fine, the only negative is the introduction of the jitter that I mentioned earlier. On a street car this isn't as critical, even on a moderate build it's not a hue deal, but on motor that's running closer to the edge or any max effort race motor the crank trigger becomes more neccesary as that 1+ degree of jitter at WOT effects your ability to put the tune exactly where you want it. Maybe you want 32 degrees of timing at WOT and 6500rpm, but due to the jitter you could get 30.5 or 33.5, or in severe cases more. The crank trigger lets you put it at 32 and it stays there.
Jerry a.k.a. 'FoundSoul'
http://www.diyautotune.com
On the wheel decoding question above, there are many ways an EMS can use a trigger wheel, crank mounted or cam mounted, to trigger an EMS. There are pros and cons to many of them. I probably won't get everything here but I'll dive in and try to hit a bunch of it and hopefully answer your questions-
While the EMS 'can' trigger at just one or two points on the wheel (usually in reference to a missing tooth if it's setup this way) this greatly reduces the resolution, or the accuracy at which the EMS tracks the crankshaft position. The more points the EMS updates crank position at, or triggers, the more accurately it can track crank position. At the same time, the more it has to track, the more processing power it takes to keep up with it all. 36-1 is good, 60-2 is great, more than that, well, you're just showing off
. Ideally a crank mounted trigger wheel is used to indicate crank position. There will be far less (almost zero) 'jitter' introduced into the system from the timing belt and camshaft in this situation. If you've ever put a timing light on a distributor based vehicle that has the trigger mechanism inside the dizzy, and put a light on a different crank triggered vehicle, you'll see a drastic difference. The light on the dizzy vehicle will seem to jump around, with the timing bouncing as much as a degree or more even at idle. The light on the crank triggered vehicle will be rock solid, the wheel may not even look like it's moving. That accuracy is a very good thing, as what you're seeing at idle happens at high rpm too, so if you want your timing to be perfectly what you tune it to be, and jitter free, crank trigger it is.
If you have a crank trigger wheel, and only a crank trigger wheel, assuming a missing tooth, you have enough information to trigger an EMS for distributor use, or for wasted spark ignition. Similarly you have enough information to fire the injectors in batch or bank-to-bank. If you want sequential injection, and sequential coil-per-plug or coil-on-plug ignition, you need something more, you need to know the exact time that cylinder #1 comes to TDC. That's where a cam wheel working alongside your crank trigger comes into play. That cam wheel in it's simplest form will have one tooth (or trigger, it could be a hall or optical setup, I'm using tooth sortof generically here) and that tooth will indicate TDC of cylinder #1. Since the cam only turns once per two revolutions of the motor, this will only come around to the sensor similarly once per two revs, and will indicate cyl1 TDC to the computer. With this info the EMS can sequentially fire the injectors and the coils in the proper order.
One more note-- this crank wheel and cam wheel can both be shoved inside a single housing and mounted on the cam, and this is common practice for many OEMs. Sometimes inside the base of distributors, and sometimes inside a separate CAS housing that triggers the ECU that then fires a wasted spark or COP ignition system. This works fine, the only negative is the introduction of the jitter that I mentioned earlier. On a street car this isn't as critical, even on a moderate build it's not a hue deal, but on motor that's running closer to the edge or any max effort race motor the crank trigger becomes more neccesary as that 1+ degree of jitter at WOT effects your ability to put the tune exactly where you want it. Maybe you want 32 degrees of timing at WOT and 6500rpm, but due to the jitter you could get 30.5 or 33.5, or in severe cases more. The crank trigger lets you put it at 32 and it stays there.
Jerry a.k.a. 'FoundSoul'
http://www.diyautotune.com
11-21-2009, 12:14 PM
#65
Three Wheelin'
11-21-2009, 06:26 PM
#66
Rennlist Member
Thanks for that post Jerry. Clears some of the issues up.
I wonder then if you are running both crank and cam sensors how you co-ordinate them based on the 'jitter' effect? I mean they should be both reading eg TDC or equivalent at the same time, no?
I wonder then if you are running both crank and cam sensors how you co-ordinate them based on the 'jitter' effect? I mean they should be both reading eg TDC or equivalent at the same time, no?
11-23-2009, 11:15 AM
#67
Addict
Rennlist Member
Rennlist Small
Business Sponsor
Rennlist Member
Rennlist Small
Business Sponsor
Just to catch up a bit (been traveling) - the 60-2 tooth gear that I have is custom laser cut to fit on the 944 crank and also to fit inside the belt covers. it uses the four mounting bolts for the AC/Alt pulley and is precison cut to fit the lip - zero runout!!
