Twin Spark Firing using single CDI Box - Page 11

Henry Schmidt · Henry Schmidt's Garage

Does anyone have an answer to this:
NASCAR uses a power supply that boosts 12v to 18v for their MSD.
Do you have any thoughts about what that does to energy delivery?

Jonny H · 02-28-2021, 07:21 AM

Quote:

Originally Posted by Henry Schmidt

Does anyone have an answer to this:
NASCAR uses a power supply that boosts 12v to 18v for their MSD.
Do you have any thoughts about what that does to energy delivery?

Yes. The MSD box does not have a regulated power supply so 18v will raise the HV voltage to around 800v. The only reason you might need that much voltage is for very high cylinder pressure.

It would lead to all sorts of problems on our cars. I know of a race car that runs a 600V ignition. Eats a plug set in two outings.

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by Jonny H

Yes. The MSD box does not have a regulated power supply so 18v will raise the HV voltage to around 800v. The only reason you might need that much voltage is for very high cylinder pressure.

It would lead to all sorts of problems on our cars. I know of a race car that runs a 600V ignition. Eats a plug set in two outings.

If this situation (18v) eats plugs after two outings, does that suggest that the energy/spark is increased?

If higher energy eats spark plugs does it also eat rotors and dist. caps?

KNIGHTRACE · KNIGHTRACE's Garage

drama time anyone ? If you like reverse my #1 and #2 I think I have the order correct.

winders · 02-28-2021, 10:19 AM

Quote:

Originally Posted by KNIGHTRACE

drama time anyone ? If you like reverse my #1 and #2 I think I have the order correct.

But William, you are one of the "cool kids" that has been bullied into posting what someone else thinks. You must be an idiot for not ever using a single MSD ignition with 2 coils in any of your builds. You must be an idiot for using 993 Twin Turbo head studs in all of your important builds.

Of course, since you are a "cool kid" and an idiot, I must be an idiot for choosing you to build my engine.

It must be just blind luck that have an engine that works at all.....

LJ851 · 02-28-2021, 10:26 AM

In the FAQ section of MSDs website it talks about running different input voltage into the MSD CDI and states that between 10v and 16v the output will be the same because the output is regulated.

LJ851 · 02-28-2021, 10:31 AM

BURN-BROS · 02-28-2021, 10:36 AM

That's the digital box. The analog MSD is not regulated.

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by KNIGHTRACE

drama time anyone ? If you like reverse my #1 and #2 I think I have the order correct.

Quote:

Originally Posted by winders

But William, you are one of the "cool kids" that has been bullied into posting what someone else thinks. You must be an idiot for not ever using a single MSD ignition with 2 coils in any of your builds. You must be an idiot for using 993 Twin Turbo head studs in all of your important builds.

Of course, since you are a "cool kid" and an idiot, I must be an idiot for choosing you to build my engine.

It must be just blind luck that have an engine that works at all.....

Talk about drama:
This is a perfect example of what happens when confirmation bias meets desperation.

LJ851 · 02-28-2021, 10:57 AM

Quote:

Originally Posted by BURN-BROS

That's the digital box. The analog MSD is not regulated.

Thanks for the clarification, Aaron.

I know some folks are having a hard time not getting bent but I think this is a great thread with valuable information.

Jonny H · 02-28-2021, 11:02 AM

Quote:

Originally Posted by LJ851

Thanks for the clarification, Aaron.

I know some folks are having a hard time not getting bent but I think this is a great thread with valuable information.

Sorry, I should have said 'some' MSD boxes are not regulated.

On that topic, here's a video I made some time ago showing how a Bosch CDI coil voltage varies with battery voltage and also RPM:

https://youtu.be/K65slwl__dk

Focker · 02-28-2021, 11:21 AM

Quote:

Originally Posted by Henry Schmidt

Talk about drama:
This is a perfect example of what happens when confirmation bias meets desperation.

Dude, just stop...You and Scottie seem to have the same illness.

Jonny H · 02-28-2021, 11:28 AM

^ yeah, not sure what I've stepped into here. Just trying to offer an EE perspective. Gonna duck out for a bit.

Focker · 02-28-2021, 11:33 AM

Quote:

Originally Posted by Jonny H

^ yeah, not sure what I've stepped into here. Just trying to offer an EE perspective. Gonna duck out for a bit.

Mark Henry · 02-28-2021, 03:54 PM

Moving right along...what is the best oil for my Porsche?

Jeff Alton · 02-28-2021, 04:11 PM

^^^^^^^ lol.

Canola?

On another note Mark, please send me an email so we can discuss the services you offer as we are always looking to make new connections....

Cheers

Fred Winterburn · 03:18 PM

Jonny, You need to buy an old MSD 6A and test it (no longer made from what I hear). The rated voltage occurs at 18V on the two I own from 20 years apart. They give a battery voltage range and then made the claim of voltage when in fact it was for 18V, not a typical 14V. The old MSD 6A is actually quite gutless when a single spark in the series is considered. I can't speak for their other products as I have not tested those. It doesn't get anywhere near 800V at 18V applied! Fred

Quote:

Originally Posted by Jonny H

Yes. The MSD box does not have a regulated power supply so 18v will raise the HV voltage to around 800v. The only reason you might need that much voltage is for very high cylinder pressure.

It would lead to all sorts of problems on our cars. I know of a race car that runs a 600V ignition. Eats a plug set in two outings.

dannobee · 03-04-2021, 05:20 PM

Nascar Cup cars quit using MSD boxes when the R07 engine came out (2011?) At least that was when it was in testing.
The biggest problem with MSD boxes in the pro categories was that some (most?) teams were adding traction control internally and nascar couldn't police it effectively. Mclaren/Freescale ECU's are effectively anti tamper proof, where any modifications are traceable and detectable at the track. The MSD boxes were routinely sent back to MSD to look for any modifications. That took days.
The way that the traction control worked was in conjunction with the rev limiting software. If the engine rpm climbed above a certain rate, the ignition timing was retarded. There were no wheel speed/driveshaft speed, car speed sensors needed, only the engine speed input. And obviously the ignition box needed to see that. We all pointed fingers at each other and it all seemed to get swept under the rug with nobody ever getting "busted" for it. Until EFI and the Mclaren ECU's came out and leveled the playing field.

Walt Fricke · 03-04-2021, 06:43 PM

Dan - great NASCAR story!

In my case, with an LSD and relatively low HP, wheel spin isn't an issue unless the track is wet or dirty. Certainly not in a straight line on dry track. Is it wheel spin the fiddling was aimed at preventing?

dannobee · 03-04-2021, 07:09 PM

Yup, wheel spin. Think about it, if you could come out of a corner, any corner, every corner, and just floor it every single time, without the risk of getting sideways, you'd look like the best driver since Steve McQueen. And the traction control was so good and so fast that it seemed seamless. Lap after lap after lap. And quite honestly, some of the most veteran drivers of all time were seething that some rookie kid could outdrive them after just a few laps on a track they've never seen before, other than on a video simulator.