MSD's and such, When to use them, and why? Options

[yeahmag]

I run these plugs as they are pre-gapped at .045":

NGK B6ES-11

-Aaron

[Razorbobsr]

We stopped selling ignition components 3-4 years ago retail. We of course still install them on turnkey engines. Selling ignition components retail is like asking for customer relations nightmares.

Capacitive Discharge Ignitions have a place with these engines, however until you reach 12:1 CR the benefits are not as great. With CR in the 13-14 range I have had to use them, because with CR increases the load on the ignition system also greatly increases.

A CDI system will allow more spark plug gap to be ran and will generally equate to smother performance at lower RPM. Note that "MSD" only allows for multiple spark discharge at below 3K RPM.

Typically a quality CDI unit will give 4HP and 6 lb/ft of torque in a 150HP 2270cc Engine. When applied to my 175HP 2270cc Performer we can see up to double those figures across the board.

The higher the CR and better the chamber filling the more benefit you will see from more intense ignition.

The porsche guy working on my engine is not looking for HP, got plenty of that it seems. We are trying to get better low end smoothness/combustion/and consistent carb mixing and across the rpm bands. He has his own dyno/flow bench,grinds his own cams, would seem hes knows his stuff??? U think? Farmersautomotive.com ot of Indy Bob

[r_towle]

If you re-read what Rick said....your lower RPM problems are where the multiple discharge systems really works well with our motors.

I would be inclined to agree with your mechanic that you may need this type of system to solve some of your issues.

The 009 distributor is also partly to blame for a big flat spot and wierd running conditions.
That distributor does not have an advance curve that matches our motors, its an compromise at best....a boat anchor to most.
Consider getting a re-done and setup distributor from http://www.tangerineracing.com
Chris Foley can help you get the correct ignition setup for your needs....a fellow HP guy with plenty of time in the seat of hopped up 914's.



rich

[Razorbobsr]

I have a HP 2L carb 44 IDF 914 that runs great above 3K, Porsche mach of some 30 yrs says I have a very solid rebuilt engine with a hotter then stock cam, the exhaust sys in too big past the collecter but header is a damn fine unit. He also says the exhaust sys has nearly no back pressure and wants to size it down from 2inch to 1 5/8 or 1 3/4, and I need to dump the TOO damn loud cherry bomb muffler. The porsche guy builds racing engines for the local Indy market, has his own dyno and flow bench, grinds his own cams, and seems to know his stuff as he only works on Porsche's. After talking to him yesterday, he thinks I also need a hotter/better eng sys, like a MSD, rather then stock 009 sys. Gents........... Your thoughts??? Questions?? Bob

Porsche guy from Indy called to let me know I could have the car back, good news! Bad news?? After playing with the engine for several hrs[$$$$] and re-jetting carbs, he has concluded that the PO had some serious cam in the car, pulls hardest above 3500 rpms, willingly revs above 6500, idles at about 1100 to 1300. Now he tells that its almost as smooth as an injected 2L[Almost] He seens to be pretty anal about things[and I mean that in the best way!] He replaced the cherry bomb muffler with something smaller that 2 inch[in] and 2 inch[out] and I think he said 1 5/8 ?? He says these engines must have back pressure to run correctly[Right?] And a 1 5/8 exhaust tip, welded the bolts to the header to ease placement, installed a second hanger for the system, he also says moving the car from the FL coast to Indy area may have played a part in the jetting[??] probs. Also installed MSD unit, he says it made a BIG difference in how the car ran, and made it easer to keep plugs cleaned off? Ok gents, and I getting hose and smoked?? Thanks, Bob

[Mike Bellis]

I'm running 4 of them in a direct fire setup. Way overkill but no more fouled plugs. I removed the idle control valve from my turbo engine and that makes the mixture rich at low rpm. I kept fouling plugs, but no more. In my direct fire mode I can get the MSD to work much higher than 3000rpm since it is only firing one plug each. The MSD is ultimately limited to internal capacitor time constants; The time it takes to charge and discharge. At the cylinder triggers increase with rpm, the MSD cannot charge and discharge the capacitor as multiples and reverts to single spark.

[brant]

I'm only running 2 of them

I've carried a spare for 6-7 years now to the track
have never needed it.

brant

[HAM Inc]

In my direct fire mode I can get the MSD to work much higher than 3000rpm since it is only firing one plug each. The MSD is ultimately limited to internal capacitor time constants; The time it takes to charge and discharge. At the cylinder triggers increase with rpm, the MSD cannot charge and discharge the capacitor as multiples and reverts to single spark.

I had figured that this was likely correct when we did the testing on our 1.8l F-Prod car.
For our hi-rev (5,000-8,000) race application running a distributor and even with a high-turns coil there simply wasn't enough time (expressed chronologically) to fire the multiple sparks over 20 crank degrees's.

Direct fire using COP's would likely really benefit from the MSD's.

But to be honest I (personal opinion being expressed here) am very leary of them (and all electronics) on a race car. I do everything I can to keep the electronics simple and to a minimum, use high quality parts (if it comes in a white box it goes into the trash with the white box ((Cole-Hersee makes excellent switches of all kinds and Hella makes a great, high quality master kill switch)) ) 3m terminals with the right crimping tools, shrink wrap and strain relief all leads, regular applications of silicone spray and say many prayers to whomever is listening up there before each race.

[Mike Bellis]

But to be honest I (personal opinion being expressed here) am very leary of them (and all electronics) on a race car. I do everything I can to keep the electronics simple and to a minimum, use high quality parts (if it comes in a white box it goes into the trash with the white box ((Cole-Hersee makes excellent switches of all kinds and Hella makes a great, high quality master kill switch)) ) 3m terminals with the right crimping tools, shrink wrap and strain relief all leads, regular applications of silicone spray and say many prayers to whomever is listening up there before each race.

I must agree here. I may opt to go with GM LS1 coils and dump the MSD's. I have to install my new 2000cc injectors and see how the engine responds to new fuel maps first.