Richards 928

Hello all,

My car is a 1980 5-speed 4.5L mostly original, low mileage, 52k.

On my shelf in my garage I have a Jacobs Ultra Pro-Street kit. Its from a previous project which I have since sold. I would like to see if I can install this kit on my 928.

I did some searches for any BTDT but not find much info. I was looking for answers to a couple of questions:

1) Has anyone had experience upgrading the 4.5L/16v ignition system with a Jacobs style CDI kit? How about other CDI like MSD? Are there any road blocks or speed bumps I am like to encounter?

2) The factory coil connection is opposite style to the Jacobs ultra coil. Is there any coil wire conversion kits available?

thx in advance
Richard

Alan

What are your goals here? what problem are you trying to solve with this?

Do you have modification plans for the engine...?

If the anwer is that there isn't anything specific driving this... I think you'd have to ask yourself why go through all the pain?

Because it certainly will be lots of work and frustration...

Alan

hacker-pschorr

Good luck, but I wouldn't bother.

The stock Porsche system is far more powerful than the domestic units those were meant for.

My US 16V made over 400rwhp with the 100% stock ignition system. I only upgraded to a system from a newer 928 so I could tune it with the Shark Tuner.

Yes, I did install an MSD unit on my car years ago, made absolutely zero difference.


The big question is, what are you trying to accomplish?

James Bailey

Right..... " Has anyone had experience upgrading the 4.5L/16v ignition system " answer is it would be a DOWNGRADE..... and the stock ignition handles the spark just fine. No low hanging fruit there...

SMTCapeCod

Amazing the extent to which some personalization/vanity mods are d'rigeur and others that aren't as common get frosty feedback.

My first 928, an '85, was set up with Jacobs when I bought. That would be Jacobs plural- a kit for each bank of cylinders. That car was crazy strong given the displacement, I'm not aware of other mods but still can't wouldn't attribute that to the ignition. Must've been because it was black 5spd and had full leather interior.

On my 83 Euro, I installed an MSD Digital setup with a very strong coil. I recall the research to ensure good coil compatibility took a lot of work...After install, I noticed prompter start, slightly smoother idle and broader tolerance of fuel tunes- but I would not attribute any additional HP/TQ to the install. I also did not calculate MPG, assuming a slight but nominal improvement. Since the car is CIS, I can't provide good insight into your install, just some additional datapoints for the pro/con deliberations.

Alan

Not at all - changing the ECU is a pretty fundamental shift - and to get it close to as good as the factory set-up is actually quite difficult. If you are contemplating major engine work that needs later adjustments anyway it could be worth it - but to just replace the stock system 'as is' there just aren't very many gains to be had... (so likely: "no gains just pains"). We would be quite remiss not to point this out - no?

It's possible to damage your engine, have a significant amount of time off the road, reduce the car's value...etc

These systems are usually targeted at Ford & Chevvy engines so these are easy out of the box set-ups... certainly not so for a 928.

Before heading down a tortuous path with possibly little chance of a pay off, it makes sense to get a reality check and understand what your motivations & expectations really are... Vs. some form of reality...

Alan

hacker-pschorr

I'm willing to bet something is amiss with the stock components and the MSD unit masked them.

No different than my local friend who installed split fire spark plugs and "proved" his MPG increased. He "forgets" to tell people the plugs he removed had well over 100k miles on them and were practically shot.

Richards 928

Alan I appreciate your interest in qualifying my approach. The answer is yes, I definitely have a goal with short term objectives. I am new to the board so will explain - my upgrade/modification plan for the car includes brakes, suspension, engine, exhaust and various ongoing restoration work it is after all a 34 year old car.

The brakes and suspension will be upgraded later this month thru an S4 conversion and we will replace the shocks same time. Next will be a Euro top-end with headers/exhaust.

In the meantime I am doing driveability and reliability stuff and that includes a look at the ignition system which brings us back to this thread.

From my experience the Jacobs system is remarkably simple - a crank trigger, a coil and an energy-pak. To install it all I need is a coil wire with proper fittings at either end and a place to fit the components. It is an add-on the original coil remains, I put the factory coil wire in the trunk in case I ever want to switch back.

So if it works then great, my Jacobs system will find a new home under the hood of the 928. If not well that is easy too - I will put it back on the shelf.

In the meantime I will continue my search for a coil wire adaptor.

Richard

Richards 928

Sorry to hear that unfortunately it happens all to often. The MSD products are often marketed to the street/strip crowd as a series of add-ons with progressive performance output (as opposed to a vehicle/system based package).

On the other hand I have seen plenty of installations with the complete article - multi-coils/CDI, high capacity looms, B&B distributors, hi-po ignition modules and so on... that work very well, wins races, some folks swear by MSD.

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Alan

OK - but what is it about the stock set-up that you are trying to improve upon?

Alan

SMTCapeCod

Alright so I put a fair bit of work into a rather lengthy response.

But, I decided it wouldn't be helpful to the O/P and would read as argumentative- deleted.

MSD Digital 6 stage left under the (+) jump terminal. HVC coil on the right.

Lindsay Racing used to be willing to craft coil leads with the different terminal connections, not sure on current status.

Richards 928

As far as I am aware my stock 1980 ignition works well enough. It is not showing any signs of failing or causing any problems. But neither is my brakes yet I am upgrading them

You may be right, the Jacobs systems may be a downgrade. I have never attempted this on a Porsche before and I assume you have or know someone who has.
If I get it to work - assuming I can get it to work I will update this thread with the results.

In the meantime I have been looking for ignition specs for my 928 but no luck so far. Some coil basics I am looking for:
- what is peak voltage?
- what is the turn ratio?
- what is primary resistance?
- what is spark duration?
- what is peak current?
- what is the drop off rate? 2k/4k/6k rpms

Perhaps you know where I can find this info?

BTW here are some of the benefits of the Jacobs system:
- built in rev limiter
- built in retard for boost/NOS
- built in anti-theft system
- peak voltage = 60,000v per strike
- will deliver up to 8 re-strikes under 4,000rpm
- will deliver up to 4 re-strikes above 4,000rpm up to 8000 rpm.
- will clean up/improve emissions
- can improve gas mileage

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Alan

Ye gods - I give up!

It seems the answer is ~ because it might be cool, and might have some benefits - that's OK - I guess you now know what you are getting into to some extent anyway.

I have done lots of things that some folks think are a bit crazy on my car - but I wouldn't do this... I always thought the spark system on our cars was one of high points. The late model EZKs esp. seem particularly bulletproof.

But that certainly doesn't mean you shouldn't go ahead and do it.

Alan

The Forgotten On

On an early car the main gain you will get from converting from the vacuum adjusted distributor to a digital ignition is mid-range torque.

Which is one of the reasons why they S2 makes more mid-range than the earlier S. The later EZK systems is way ahead of the earlier systems before 85 US.

Richards 928

Well I have no objective proof the existing system is under-performing.

On the other hand I have enough experience with the Jacobs system to know that it can provide verifiable improvements in performance if it can be adapted to the vehicle.

I am trying to see if successfull application of this system to my 928 results in verifiable, measurable improvement in responsiveness and performance.

Originally I asked "... Has anyone had experience upgrading the 4.5L/16v ignition system with a Jacobs style CDI kit?..."

Looks like I will be the first. If it does result in a verifiable, measurable improvement then don't we all stand to gain?

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