Coil Per Cylinder or Single Coil for SBC to 6500 RPM

[Guest Mike]

Hi All... I apologize if this has been covered already. I searched and found nothing.

 

BTW... I'm learning a LOT here. THANK YOU!!!

 

I've been on this forum looking for advice as to whether I should keep and mod my low mile Gen1 SBC or just swap for a LS1. THIS ISN'T MY QUESTION... I've decided to mod the current SBC for simplicity and $$$ issues.

 

The car is a HybridZ (of course) with a semi-stock 350 SBC and TH400 transmission. I will eventually swap to a TH700R4 (or similar) because I want an OD... THIS ISN'T MY QUESTION EITHER. Differential is an R200... soon to have a Quaife or similar Torque Biasing unit... and with a 3.7:1 Ratio.

 

Bottom line on the engine (when I'm done): It'll have 400-450 ft-lb of torque peaking at about 4500 RPM. BHP will peak at approximately 400 at about 5500 RPM (before nitrous). Final CR is about 10:1. I expect the engine to pull fairly hard up to 6500 RPM... I will NEVER rev it past that because I don't know if the short block will safely spin higher... BTW, I don't want to rebuild the short block. I'd really like to push the limits a bit with an additional 100HP of nitrous... no more than this (hyper pistons)... for a total of approximately 500HP when sprayed... emergencies only ;^)

 

I'm almost ready to make my decisions regarding heads, roller cam/lifters, roller rockers, intake/carbs, ignition, exhaust, etc. NOPE... NOT MY QUESTION.

 

MY QUESTION (finally): Is it worth converting to a Coil-Per-Cylinder ignition system... or is my 6500 RPM limit just as well served with a Multi-Spark Controller and a Single Coil?

[dr_hunt]

Hi All... I apologize if this has been covered already. I searched and found nothing.

 

BTW... I'm learning a LOT here. THANK YOU!!!

 

I've been on this forum looking for advice as to whether I should keep and mod my low mile Gen1 SBC or just swap for a LS1. THIS ISN'T MY QUESTION... I've decided to mod the current SBC for simplicity and $$$ issues.

 

The car is a HybridZ (of course) with a semi-stock 350 SBC and TH400 transmission. I will eventually swap to a TH700R4 (or similar) because I want an OD... THIS ISN'T MY QUESTION EITHER. Differential is an R200... soon to have a Quaife or similar Torque Biasing unit... and with a 3.7:1 Ratio.

 

Bottom line on the engine (when I'm done): It'll have 400-450 ft-lb of torque peaking at about 4500 RPM. BHP will peak at approximately 400 at about 5500 RPM (before nitrous). Final CR is about 10:1. I expect the engine to pull fairly hard up to 6500 RPM... I will NEVER rev it past that because I don't know if the short block will safely spin higher... BTW' date=' I don't want to rebuild the short block. I'd really like to push the limits a bit with an additional 100HP of nitrous... no more than this (hyper pistons)... for a total of approximately 500HP when sprayed... [b']emergencies only ;^)[/b]

 

I'm almost ready to make my decisions regarding heads, roller cam/lifters, roller rockers, intake/carbs, ignition, exhaust, etc. NOPE... NOT MY QUESTION.

 

MY QUESTION (finally): Is it worth converting to a Coil-Per-Cylinder ignition system... or is my 6500 RPM limit just as well served with a Multi-Spark Controller and a Single Coil?

 

If that is a stock short block, IMO your pushing the limits of the rod bolts at 5500rpm. IMO I doubt you find any HP or TQ gains using anything other than an MSD or HEI with a good module and HP coil.

[Guest Mike]

If that is a stock short block, IMO your pushing the limits of the rod bolts at 5500rpm. IMO I doubt you find any HP or TQ gains using anything other than an MSD or HEI with a good module and HP coil.

 

Thanks dr_hunt,

 

This was sold to me as "better than stock"... means absolututely nothing. But it came in the Ferrari replica I just bought. If I blow it apart, I'll be forced to buy another power plant ;^)

 

Just as I suspected on the ignition... I'll keep it simple.

[getZ]

When ever I have questions like that I look and see what other people are using and/or getting away with.

 

The individual cylinder single coil packs are only something that has come out fairly recently (within the last 10 years on stock OEM stuff). Circle track guys and a lot of drag race guys still use single coil setups past 8000 rpm with no problems. Yeah sure, the multi-coil setup has been used in racing longer than that, but only on higher end race classes, unless of cours the cars came with them stock.

 

I'm not really sure what the multi-coils give you for an advantage. I'm thinking it was more for reliability that performance. You don't have to run a high voltage (50,000 volts) over a long distance, hence less susceptability to arcing, but that's just my opinion.

[Guest Mike]

When ever I have questions like that I look and see what other people are using and/or getting away with.

 

The individual cylinder single coil packs are only something that has come out fairly recently (within the last 10 years on stock OEM stuff). Circle track guys and a lot of drag race guys still use single coil setups past 8000 rpm with no problems. Yeah sure' date=' the multi-coil setup has been used in racing longer than that, but only on higher end race classes, unless of cours the cars came with them stock.

 

I'm not really sure what the multi-coils give you for an advantage. I'm thinking it was more for reliability that performance. You don't have to run a high voltage (50,000 volts) over a long distance, hence less susceptability to arcing, but that's just my opinion.[/quote']

 

Thanks for the single coil vote. One it is!!

[Pop N Wood]

Coils tend to saturate if you send pulses of energy through them at too fast a rate. Multiple coils allow the pulse rate through each coil to be reduced giving them more time to charge up for the next pulse. From a purely technical point of view it is better than a single coil. Or at least it means the coil design is not as demanding. But like said above you can make big power on single coil systems.

 

IMO one of the biggest advantages of multi coil set ups is getting rid of the high voltage switch in the distributor cap. For a pure race car this may not be a big issue because of the high level of maintenance that is done to the cars on a regular basis. But for a street car, getting rid of the dist cap is huge in terms of reliability.

[Guest Mike]

Coils tend to saturate if you send pulses of energy through them at too fast a rate. Multiple coils allow the pulse rate through each coil to be reduced giving them more time to charge up for the next pulse. From a purely technical point of view it is better than a single coil. Or at least it means the coil design is not as demanding. But like said above you can make big power on single coil systems.

 

IMO one of the biggest advantages of multi coil set ups is getting rid of the high voltage switch in the distributor cap. For a pure race car this may not be a big issue because of the high level of maintenance that is done to the cars on a regular basis. But for a street car' date=' getting rid of the dist cap is huge in terms of reliability.[/quote']

 

Without a distributor cap (and rotor), what tells the coils when to fire the plugs:eek:

[Pop N Wood]

The switching is done on the low voltage side by only sending 12V to the coil connected to the plug about to be fired. I guess it is done by the computer.

[Guest Mike]

The switching is done on the low voltage side by only sending 12V to the coil connected to the plug about to be fired. I guess it is done by the computer.

 

 

Mine doesn't have a computer.

 

Maybe he meant these have rotors, but no caps... or simplified caps? I can understand how that would work but not without a rotor. I'll research this when I have more time. I feel "stoopid" every time I read replies to my own posts.

[Pop N Wood]

I don't understand. If you have some type of multi coil set up, then you have to have some type of device which senses the crank position and triggers the spark. The spark controller will have a separate wire going to each coil, which in turn is connected to individual plugs. The spark controller (or computer) will send the power to whatever coil is feeding the plug it wants to fire.

 

What I meant is there is no rotor between the coil and the plug. Thus no change of getting carbon tracing inside the cap hence crossfires between plugs.

[jt1]

Without a distributor cap (and rotor), what tells the coils when to fire the plugs

 

Generally a magnetic trigger on the crank, working thru the ECU.

 

jt

[Guest Mike]

I don't understand. If you have some type of multi coil set up' date=' then you have to have some type of device which senses the crank position and triggers the spark. The spark controller will have a separate wire going to each coil, which in turn is connected to individual plugs. The spark controller (or computer) will send the power to whatever coil is feeding the plug it wants to fire.

 

What I meant is there is no rotor between the coil and the plug. Thus no change of getting carbon tracing inside the cap hence crossfires between plugs.[/quote']

 

I'm sorry I misunderstood. I thought you were saying there is no crank position sensor and I knew of no way to make that work. You're saying there IS a rotor... just runs at 12-15v not high voltage. I should have better deciphered what you meant. Like before, I feel fairly stoopid now.

[Guest Mike]

Generally a magnetic trigger on the crank' date=' working thru the ECU.

 

jt[/quote']

 

Thanks jt1. I thought he meant there is no crank position sensor at all... and this "confyoozed" me:icon56: