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-   Porsche 911 Technical Forum (http://forums.pelicanparts.com/porsche-911-technical-forum/)
-   -   Discussion on the Future of CDI Boxes (http://forums.pelicanparts.com/porsche-911-technical-forum/897110-discussion-future-cdi-boxes.html)

Reiver 01-04-2016 08:46 PM
Quote:
Originally Posted by Ronnie's.930 (Post 8943817)
^^^

"Getting" is the operative word, my friend (as opposed to "giving")!!!!
Pitching/catching you're still playin ball......no AC in an older sports car...too much weight/power drain.

dicklague 01-04-2016 09:02 PM
Quote:
Originally Posted by jjeffries (Post 8944002)
Mr. Lague et al, what system would choose if you were on a tight budget? Hypothetically I'm talking about .... me....way too skint (British term for short-of-funds) for a $1500 system, lovely though it looks, but I would like a plan for if/when my Permatune takes a dump. Do you feel that Crane makes better stuff than MSD? If yes, is their technology better than MSD's or do you think they just make more reliable stuff? The MSD Streetfire which started this discussion is neat, mainly because it fits well in the allocated space, in addition to being reasonably priced. I guess its reliability remains to be seen. Thanks, John
The MSD Streetfire is a bargain. Summit racing has a similar one for a couple dollars less. Just remember you should also have a good coil and a E type transformer coil is the way to go. Crane builds good product generally, but I can't comment on technology or reliability with any personal experience.

I have 5 years of experience with the Daytona-Sensors CD1 in my 1973 MFI 911 and it has been great and very reliable. Comes with a stout matching coil for a suggested retail of $595.00 USD. It is not the cheapest but I feel very good value for all the features it has.

I have a Streetfire and will do some testing on it soon.

Ronnie's.930 01-04-2016 09:07 PM
Quote:
Originally Posted by Reiver (Post 8944040)
Pitching/catching you're still playin ball......no AC in an older sports car...too much weight/power drain.
Good point (just the errr, "point" :eek:) , but when your old sports car has one of these tucked behind the rear bumper, then even a highly modified a/c system (even more weight and power draw) is shown who's boss, hoss!!!

http://forums.pelicanparts.com/uploa...1451973982.jpg

VFR750 01-05-2016 02:41 AM
I'd also be interested in fuel quality over the years.

But some personal observations. Porsche designed the SC for 10% ethanol. Says right in my owners manual.

I have ready access to e10 93 octane. That is better than what the car was designed to so there is opportunity to up the advance.

I run a wideband AFR system. So I can change jets to offset the E10 flow requirements. Effectively my target AFR range accounts for the lower optimal AFR for the E10 mix.

But I have a 34 year old cdi box. And I do see a lot of fluctuation in AFR. Especially at idle and low throttle. A comment was made about this. Interesting that one other person sees the same thing. Maybe more?

Fuel and oil composition has been driven by the EPA. Mainly to reduced emissions. But also to improve the longevity of the pollution control devises. Just say ZDDP in these parts and you'll be in a fight! That "improvemt" might be exploitable now, with newer designs, verses the existing boxes.

Jonny H 01-05-2016 06:14 AM
The main point is that the fuel today burns a a different rate:

Quote:
Getting the ignition timing of your classic's engine right is a critical part of getting it to run properly. Get it wrong and you can adversely affect performance, economy and even engine longevity. Get it right and you can enjoy smooth, responsive and practical classic motoring.

But now that the leaded fuels our cars were originally designed to run on have been withdrawn from garage forecourts and replaced with chemically different unleaded petrol, vehicle owners handbooks can no longer be relied upon to provide accurate ignition timing figures.
Full article here:

The Classic Mechanic: Ignition Timing with Modern Fuels

wwest 01-05-2016 07:39 AM
Quote:
Originally Posted by Jonny H (Post 8943567)
I was essentially invited to this discussion by the OP mentioning our product. I really thought you'd be interested in knowing some of the shortfalls in the Bosch design. The shortfalls were actually listed not by me, but by Dave and confirmed by folks who fix original boxes. I then listed 8 de facto improvements over the original design in post #42. All of those are aimed at reliabilty.

That is before we even consider timing adjustment which is a well proven path to performance. If it weren't then MSD, Daytona, Canems, Motec, Megasquirt and of course ALL the major car manufacturers have got it wrong. All the guys who 'recurve' distributors would be out of a job too. I can't believe this is even being called into question on a car forum.

The boxes are subject to all kinds of testing, including cold/heat. We always prefer real world trials so we have a number of test mules out there. We have found issues this way and we resolve them. It is called constant improvement, it is what engineers do.

I am pleased to report that we have had no component failures in over 100,000 miles of testing.

wwest, as you don't know what that capacitor is doing in the circuit, how can you possibly make a judgement on whether it is fit for purpose? FYI, the 600V HV charge caps are on the other side of the board.
Yes, ~1uf bipolar 600 volt capacitors are large enough that it's obvious they are not pictured.

You made the cover-all statement that CDI+ capacitors are 600 volt, obviously you meant only the charge capacitor(s).

I suspect that had you stopped the design without all the bell and whistles, a simple (KISS) modern day implementation of the OEM product you would have a much more viable (more reliable, less expensive, product for the designated market.

VFR750 01-05-2016 07:40 AM
Interesting article. Slower burning fuel would suggest we need more advance then when the car was originally designed for optimal power.

Kinda explains how I ended up at 10 BTDC for my idle setting.

It ran poorly when I first starter the engine with the carbs. Timing was ATDC. Quickly moved the distributor to get to 5-6 BTDC and it ran pretty good. Then went for more knowing I also wanted more above 3000 rpm.

I ran 8 BTDC for a while, bumped it to 9 then finally felt 10 BTDC was enough. didn't try to go any farther. Idles nice. No pinking. Pulls cleanly. Turn it up to 11???

tirwin 01-05-2016 07:42 AM
What's your total advance at?

VFR750 01-05-2016 07:46 AM
Wwest

You are probably right the development time and cost would have been less. And likely the product cost.

But I seem to remember that adding a electronic rev limiter was desired to eliminate the use of the rev-limiter rotors. Which apparently are pretty abrupt. This added feature affects many of the early models of 911 engines.

So perhaps that feature alone is a valuable addition, and possibly a deciding factor all along.

VFR750 01-05-2016 07:48 AM
Quote:
Originally Posted by tirwin (Post 8944408)
What's your total advance at?
Around 28 BTDC. Limited by the 79 distributor design.

wwest 01-05-2016 07:55 AM
Quote:
Originally Posted by VFR750 (Post 8944419)
Wwest

You are probably right the development time and cost would have been less. And likely the product cost.

But I seem to remember that adding a electronic rev limiter was desired to eliminate the use of the rev-limiter rotors. Which apparently are pretty abrupt. This added feature affects many of the early models of 911 engines.

So perhaps that feature alone is a valuable addition, and possibly a deciding factor all along.
Not exactly comfortable with having that much, 5/6, unburned A/F mixture in the exhaust.

And I am still of the opinion that a modern day Kettering/inductive ignition would have been a better design.

VFR750 01-05-2016 08:04 AM
I think the soft limiter gives you warning early enough to avoid the hard limit. No warning with the rotor.

Whether it's all off or one cylinder per rev, there's a lot of fuel to be burned when the rpm come down!

It's an interesting point about the style.

How would you go about doing a Kettering style? Would it be harder to fit in the box? Could you retain the other ignition components or does this require other improvements?

Bob Kontak 01-05-2016 08:21 AM
What is any of this modern CDI bid-ness going to do for someone with a sub 200hp car with 8.5:1 compression?

I have an 81. More compression but it can't breath. VFR750's 79 will walk my 81.

Da fuk is a fancy spark going to do for either of us? Two hp?

My car came with Permatune. Failed. Bought another. Failed. MSD 13 years later is fine.

Wish it would have had a Bosch. I could have just had it repaired.

RDM 01-05-2016 12:28 PM
Quote:
Originally Posted by wwest (Post 8944435)
And I am still of the opinion that a modern day Kettering/inductive ignition would have been a better design.
Then by all means design it, build it, and try and sell it to us. That would earn some respect. If it survives in the market, that would earn some respect.

Jonny's done that. Why not you?

dicklague 01-06-2016 03:34 PM
Quote:
Originally Posted by RDM (Post 8944843)
Then by all means design it, build it, and try and sell it to us. That would earn some respect. If it survives in the market, that would earn some respect.

Jonny's done that. Why not you?
good point+++++

RSTarga 01-06-2016 07:06 PM
When my CDI takes a crap I will pony up for one of jonny's units.
My criteria, soft rev limiter so I can get rid of the unreliable spring loaded rotor.
Original box for the purists.
Modern solid state electronics.
Adjustable advance curve.
I love my old tube HiFi, but its not exposed to vibrations and temperature ranges.
Our CDI boxes were designed when we went to the moon on slide rule calculations.
I still had my Zenith Transoceanic Radio.
My point of view is, if it visibly looks original but is 45 years of engineering later, it goes on my car.
By the way our fuels in the US are no where near as good as they were 45 years ago. Nothing like that leaded 100 octane Chevron at the pump.


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