MSD belt driven distributor question
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From: lombard,IL
MSD belt driven distributor question Im looking to go to the belt driven distributor setup because im hearing at high rpms the standard coil setup seems to have some problems.Now if i go to a distribuator setup can my BS3 be converted to run a distributor setup?If i have to get a new engine mangment system i might scratch this thought.I know we will be spinning the motor 9000 plus rpms so i really don't want to be chasing a unhappy motor because of ignition problems.
Yes, the BS3 run the dist, but you will have to send you box in and have it converted, or exchanged for a standard SBC box. I run a MSD crank trigger, Jesel belt drive dist, and a MSD 7531 box with mine, and no problems to 9900rpms. MSD has a new converter box that will take the signal from the stock crank trigger and fire an MSD box, but it must be used with a dist. The purpose of the converter is to not have to use a front mounted crank trigger. Jesel has a bolt on dist and bracket for an ls1/lsx block with a Jesel belt drive. I have seen tham on some engines at LME.
if by distributor you mean one ignition coil feeding into a distributor cap, with a rotor underneath, that is the worst thing you could do.
a traditional distributor is not bad, it has it's place because of it's simplicity and ease of maintenance and tuning. But with high rpm anything mechanical that has to be accurate, isn't going to be accurate. Not like a magnetic pickup sensor off the crankshaft, this is the best thing for timing accuracy, and you can spin the motor any rpm you like. The ignition [computer] can work off the signal very accurately.
having 1 ignition coil (as in a distributor setup) has high rpm problems because there is less time for it to build spark. The higher the rpm, the less time for the coil to saturate and it produces a weaker spark, and the engine eventually sputters.
Having a distributorless ignition is the way to go because it opens the door for a coil-per-cylinder setup, basically because you now have a computer that controls things. This is having one coil per cylinder, opposed to 1 coil for all 8 cylinders. So by a coil for each cylinder, on an 8 cylinder the time the coil has to generate spark is improved by a factor of 8.
Consider the traditional 350 chevy running 5000 rpm no problem on a distributor with 1 coil for 8 cylinders. Now go to 1 coil for each cylinder, at 10000 rpm (twice the rpm) each coil still has a 4x length of time to build spark compared to 1 coil for all 8 cylinders at 5000 rpm.
a traditional distributor is not bad, it has it's place because of it's simplicity and ease of maintenance and tuning. But with high rpm anything mechanical that has to be accurate, isn't going to be accurate. Not like a magnetic pickup sensor off the crankshaft, this is the best thing for timing accuracy, and you can spin the motor any rpm you like. The ignition [computer] can work off the signal very accurately.
having 1 ignition coil (as in a distributor setup) has high rpm problems because there is less time for it to build spark. The higher the rpm, the less time for the coil to saturate and it produces a weaker spark, and the engine eventually sputters.
Having a distributorless ignition is the way to go because it opens the door for a coil-per-cylinder setup, basically because you now have a computer that controls things. This is having one coil per cylinder, opposed to 1 coil for all 8 cylinders. So by a coil for each cylinder, on an 8 cylinder the time the coil has to generate spark is improved by a factor of 8.
Consider the traditional 350 chevy running 5000 rpm no problem on a distributor with 1 coil for 8 cylinders. Now go to 1 coil for each cylinder, at 10000 rpm (twice the rpm) each coil still has a 4x length of time to build spark compared to 1 coil for all 8 cylinders at 5000 rpm.
Believe me I understand about the dwell time and more energy to the spark plug, as well as the infinetly tuneable spark curve. I am not going to spend 10 to 20 thousand dollars to get an engine management system that will run a coil on plug system at 9000 plus rpms. I did not want to spend a lot of time trying to figure out what would work, and decided to install something that I knew would definatley function at 9000 rpms plus. I know of a lot of Comp Eliminator, and Pro Stock cars and such that run all the MSD stuff and never have problems up to 11,000rpms. I see that the fastest turbo doorslammer in the country uses a single coil with no issues. It makes in excess of 2500hp, it seems to have no trouble with one coil, and a 7531 box.
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From: lombard,IL
Yes, the BS3 run the dist, but you will have to send you box in and have it converted, or exchanged for a standard SBC box. I run a MSD crank trigger, Jesel belt drive dist, and a MSD 7531 box with mine, and no problems to 9900rpms. MSD has a new converter box that will take the signal from the stock crank trigger and fire an MSD box, but it must be used with a dist. The purpose of the converter is to not have to use a front mounted crank trigger. Jesel has a bolt on dist and bracket for an ls1/lsx block with a Jesel belt drive. I have seen tham on some engines at LME.
we're running COP/BS3 in Tom's radial car to 9000 RPM don't see what the issue is? 
Still on the stock crank target wheel, but there is some concern about signal dropout from the sensor about 9500. Switching to an equal tooth wheel on the damper fixes that though.
Who exactly told you it has problems?
Still on the stock crank target wheel, but there is some concern about signal dropout from the sensor about 9500. Switching to an equal tooth wheel on the damper fixes that though.
Who exactly told you it has problems?
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Im looking to go to the belt driven distributor setup because im hearing at high rpms the standard coil setup seems to have some problems.Now if i go to a distribuator setup can my BS3 be converted to run a distributor setup?If i have to get a new engine mangment system i might scratch this thought.I know we will be spinning the motor 9000 plus rpms so i really don't want to be chasing a unhappy motor because of ignition problems.
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Verdad Gallardo No, one told me this problem I experience it first hand. The very first combo I had with and ls2 block and the stock 24x crank wheel, would not rev over 8500rpms. We even tried John Meanys billet dampner mounted trigger wheel. You could start the car and put n 2 step, and watch the timing and it would drop 15 degrees every other revolution, and cut off. We tried changing grounds, changing coil packs, different crank sensors and different cam sensors I finally got frustrated with it and scrapped the stock coils in favor of the Msd stuff.
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From: lombard,IL
Sixspeed inc are you guys running the standard bigstiff without the coil drivers?The reason i ask is im in the prosess of selling my current bigstuff for an ls1 and just buying the one without the coil drivers.Also im putting in the msd 7531 looks like a real nice setup.
To expand on this a bit, didn't the FAST computers have a high rpm problem with factory coils as well? If the BS3 also has these issues, does anyone really know if this is a glitch in aftermarket interfaces, or something inherent to the GM coil design? I always figured the 8000rpm limit in the factory computer tables was just because anything more was unnecessary on a factory motor. However, could it be something GM engineers know about the factory coil system? It seems highly counter-intuitive that separate coils would be < a single coil, but we all know what happens when intuition fights facts.
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From: lombard,IL
Thanks,Mike
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8 SEC SLOPPY SHOT!!!
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From: lombard,IL
I'm thinking since the coils are no longer being used it's only working off of the crank and cam signal.And the cam signal is only used to control sequenal timing or fueling.So im thinking the box is getting converted to read a msd crank trigger setup instead of the stock one on the crank that will no longer be on my setup.I could be way off on my thinking, Maybe it's time for a beer!!!
No, one told me this problem I experience it first hand. The very first combo I had with and ls2 block and the stock 24x crank wheel, would not rev over 8500rpms. We even tried John Meanys billet dampner mounted trigger wheel. You could start the car and put n 2 step, and watch the timing and it would drop 15 degrees every other revolution, and cut off. We tried changing grounds, changing coil packs, different crank sensors and different cam sensors I finally got frustrated with it and scrapped the stock coils in favor of the Msd stuff.
The issue on the factory 24X wheel is the resolution of the target and sensor pair at high speed. The split wheel/mirror configuration and alternating tooth sizes (really the 5 degree tooth) is the issue. Things become a blur to the sensor as you go up in speed, nothing to do with the box doing the control.
dropping advance is due to a loss of cam sync, more than likely with the cam resync turned off.
The issue on the factory 24X wheel is the resolution of the target and sensor pair at high speed. The split wheel/mirror configuration and alternating tooth sizes (really the 5 degree tooth) is the issue. Things become a blur to the sensor as you go up in speed, nothing to do with the box doing the control.
The issue on the factory 24X wheel is the resolution of the target and sensor pair at high speed. The split wheel/mirror configuration and alternating tooth sizes (really the 5 degree tooth) is the issue. Things become a blur to the sensor as you go up in speed, nothing to do with the box doing the control.
Shouldn't the lower resolution be less of a blur at higher RPM? at 9,000 RPM the 24x reluctor should be ~3600hz signal instead of the ~8700hz signal for a higher resolution 58x reluctor. I know its not entirely related but where I work there's a large high speed (615ft/min) conveyor system that counts a pin every 5" for fault detection, we had to upgrade to a high speed coutner module to tell the PLC an integer instead of flagging an input every time a pin passed because it was just missing pins, and that's less than 25hz, not to meniton what we're using is the highest quality high speed counters available. I'm not sure if BS3 or any other aftermarket EFI system has high speed counter modules on them but I can almost gaurantee they do. I'm sure the difference between efi controllers being able to succesfully control CDI or individual coil ignitions at high RPM lies in these modules.
the wheel teeth are in a non repeating pattern of short and long teeth(5 degrees high, 10 degrees low or the inverse), and the wheel is spilt with a mirror image side by side. The sensor itself begins to lose it's wits above 8000 to 8500 depending on air gap and runout on the wheel. On a spin fixture the sensor output just disappears, but if you simulate the signal the stock PCM or BS3 will happily keep right on going.
Stock PCM uses a dedicated ASIC for crank decode and routing to the coils, not sure on the BS3.
It's simply a "feature" of the stock target wheel and sensor combo. Nothing to do with the box getting the info.
It takes very little CPU HP to read a crank signal. A MAF input is orders of magnitude higher frequency and those are common place.
Stock PCM uses a dedicated ASIC for crank decode and routing to the coils, not sure on the BS3.
It's simply a "feature" of the stock target wheel and sensor combo. Nothing to do with the box getting the info.
It takes very little CPU HP to read a crank signal. A MAF input is orders of magnitude higher frequency and those are common place.
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From: Fenton, MI
Why wouldn't you give what you have a try?
Im looking to go to the belt driven distributor setup because im hearing at high rpms the standard coil setup seems to have some problems.Now if i go to a distribuator setup can my BS3 be converted to run a distributor setup?If i have to get a new engine mangment system i might scratch this thought.I know we will be spinning the motor 9000 plus rpms so i really don't want to be chasing a unhappy motor because of ignition problems.