MSD questions

[mjmoran]

You CAN use the stock Beru wires. Just not the best -- although if your saving money...

Next service, get the KV 85 Magnacores (rennsport systems has em.) I think they are around $200.00 for the set...

[Steve@Rennsport]

Yessir,........

Do not use any solid core wires with MSD's. They MUST have suppression wires for EFI elimination and better coil saturation.

Magnecor, MSD, and Moroso spiral-wound suppression wires are all OK.

[david c.]

Thanks Steve. I think I'd better talk with the guy who worked on my engine!

[randywebb]

search on solid core and (I think) Grady Clay...

msd seems out of the 911 loop - I guess we are a very small slice of the market for them

[Steve@Rennsport]

Randy:

There is a LOT more to this than meets the eye and yes, MSD IS well out of the 911 "loop",....

All one has to do is call them with a tech question/problem about a 911 and see what kind of an answer you get.

MSD's require a high level of EMI suppression to ensure that the ignition is reliable to 6K and beyond. Porsche uses solid core wires and puts their suppression into the notoriously unreliable Beru plug connectors. While its OK in some applications, using spiral-wound suppression wire works much better and prevents some misfiring issues that occur at high RPM.

Magnecor wires use their own plug connectors that have no resistors and they are FAR more durable in every way.

Porsche AG has been well behind current (pun intended) plug wire/connector technology here until their latest cars which use coil-on-plug stuff eliminating those infernal Beru connectors.

[david c.]

This is great info. Thanks guys. My little 912 needs every last hp there is out there to be had in order to be a competitive autocrosser. I'm really glad we're discussing this.

[randywebb]

Thxs Steve. I never knew it would actually run on a blue coil or that it might endanger the msd box, just that you weren't supposed to use one...

[Steve@Rennsport]

Originally posted by randywebb
Thxs Steve. I never knew it would actually run on a blue coil or that it might endanger the msd box, just that you weren't supposed to use one...

LOL,......About 2 years ago, I had a major disagreement on that subject with my partner as he didn't think the coil made any difference.

After a few runs on the engine dyno using the same engine equipped with MSD 6AL's testing both kinds of coils, I made my point.

MSD's require a specific "load" on the amplifier to work properly much like speaker impedance on class A & AB amplifiers.

[david c.]

I have a Blaster 2 coil in my box of spares. I'm going to swap coils tomorrow and report back.

By the way, how about NGK wires? They aren't solid cores. Should work okay?

[RoninLB]

[bigchillcar]

how are the ribs, ron? little jaunt still backed-up a cpl weeks?
ryan

[RoninLB]

Originally posted by bigchillcar

how are the ribs, ron?

24+8hrs and I just realized that broken bones will need months for repair.

Scuba&Free diving made me start thinking. Actually what started the thinking is the 20-30# Stripped Bass that are currently being slammed 200' from my 911. I'm so wasted I started about taking pics. Did a few nice ones on that current 2 Reg thread.

back to topic.. Is anyone doing a new MSD install? I have some ready made pics.

[bigchillcar]

yes..good drugs will become your new favorite ally..

yep, back to our regularly scheduled topic.
ryan

[ValveFloat]

Your MSD will start and run OK with Bosch blue coil; you simply lose 4-6 HP.

Interesting. So is that a loss vs. running without CDI and Bosch coil or a loss vs. with CDI with Bosch coil?
The reason I'm asking is I installed a Crane CDI box on my '68 911, and I dynoed the car with the CDI connected and disconnected. I saw basically no gain from the CDI. I am wondering, does it take the correct wires and coil to realize the benefits of the CDI, or maybe there is some other reason I gained nothing from the CDI install.

Thanks


Click for a larger image.

[Yellowbird RS]

No tach adapter needed for a '74 Carrera.
My set-up:
MSD 6AL, MDS HV Blaster Coil 2, magnecore R-100 racing wires, denso Iridum IW-20 spark plug .39 gap, new distribuitor cap and petronix on my tool box waithin to be installed

my last week thread

[jluetjen]

Joe; I think that the performance gains of a lot of ignition systems are oversold. If a car has an ignition system that provides a strong enough spark at the right time, across the full rev range -- well it doesn't get any better then that. The Porsche 911 ignition system pretty well fulfills those requirements with the following exceptions.

1) The very early car's had a tendency to foul plugs. The original Bosch electronic ignition system pretty well fixed that.

2) Cars with 2.0 heads (like yours and mine) and high compression pistons have a combustion chamber (at TDC) which has too much distance (and too many obstructions) between the spark plug and the outer edge of the cylinder. As a result it's not uncommon to have the cylinder not ignite (or not combust completely) at low rev's with the throttle closed (which causes the combustion and mixing to slow down even more). Using an multi-spark ignition gives the ignition system a "mulligan" if the initial spark fails to ignite the mixture. It occurs later in the cycle, but a late ignition is still better then none. As a result in my car it idles better, and runs better under light throttle and engine speeds < 3000 RPM. Above 3000 RPM I doubt it provides any real improvement over the stock system.

Finally, replacing the points with something like a crank-fire system eliminates a wear item in the system. As a result it can't wear out of spec like points can if they are neglected or set incorrectly.

For the most part that's it. Looking at your dyno chart, I can see a very clear and significant improvement at 2300 RPM. Given that your profile says that you like to autocross, I would think that this would be meaningful.