600V DC from 12V DC Source

shortbus

Joined Sep 30, 2009
10,045
When I wrote "alternative" I was referencing the Mark Ten CDI system. Sorry I was not clear on that point. The Mark Ten was much less expensive than the real HEI system.
There were many of those type systems back in the past, Judson was another popular one. But when modern reluctive ignition systems came out in the OEM and then into the aftermarket, it's funny that all of those "great" ignition ideas disappeared. Because they were just a crutch, not an innovation or really viable reliable system.

You seem from your different posts about cars and racing to be either someone that never did it or someone that didn't really understand(my guess from other statements in your posts)) what you read in a magazine. There are many like you.
 

Papabravo

Joined Feb 24, 2006
21,159
There were many of those type systems back in the past, Judson was another popular one. But when modern reluctive ignition systems came out in the OEM and then into the aftermarket, it's funny that all of those "great" ignition ideas disappeared. Because they were just a crutch, not an innovation or really viable reliable system.

You seem from your different posts about cars and racing to be either someone that never did it or someone that didn't really understand(my guess from other statements in your posts)) what you read in a magazine. There are many like you.
Not just in racing, or cars in general. We have a guy here who thinks Schrodinger was a peasant, and Dirac was an idiot.
 

shortbus

Joined Sep 30, 2009
10,045
My brother bought a knockoff HEI out of China for 60 bucks with the coil mounted on top for his CJ7. Did it work yah you instantly wanted the points back because it was noisy and had huge unexplainable dead spots. A good HEI costs the same as a dist. Msd/black box etc. and coil.

Like one of the the comedians says, "well, there's your problem". Exactly what noise are you talking about? Or dead spots?

You probably don't know that you don't even need a HEI distributor to use one of the HEI modules, with the points. The only reason people use and like the MSD isn't because it is so much better it's the extra things that are built into it, like a rev limiter and multi strike capability. Then there is the bragging right at a car show saying "look I have a MSD". Just adding a MSD box to something isn't going to end problems or make an engine run better.

While this is in a Triumph it is from a guy that knows the score.
 

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Ian0

Joined Aug 7, 2020
9,668
Like one of the the comedians says, "well, there's your problem". Exactly what noise are you talking about? Or dead spots?

You probably don't know that you don't even need a HEI distributor to use one of the HEI modules, with the points. The only reason people use and like the MSD isn't because it is so much better it's the extra things that are built into it, like a rev limiter and multi strike capability. Then there is the bragging right at a car show saying "look I have a MSD". Just adding a MSD box to something isn't going to end problems or make an engine run better.

While this is in a Triumph it is from a guy that knows the score.
Having read that, I'd go for the optical system any day. It appears that the variable reluctance system gives a slopy waveform with no distinct edges that needs a comparator for reliable operation. If I need information on the rpm I'm much rather infer it from the time period between the pulses than try to determine it from the voltage from a reluctance sensor. What happens if the gaps vary? Or the magnetic field strength changes, or it gets rust particles in it? Seems like I might be better off adjusting the points.
It doesn't sell it to me!
The control system on the diesel generators we use has a reluctance sensor to determine engine speed. It's the only sensor we regularly have to change.
 

Thread Starter

MGPERF

Joined Jun 8, 2021
77
That early post statement told me quite a bit about your engine expertise
Shortbus..... The advance inside the distributor is tack welded in place because the timing curve is controlled by a computer with a vacuum adv. sensor. If I had the mechanical advance still functioning with the computer (no knock sensor) then it'd be running something like 60 degrees adv. at WOT and my engine would go boom. A 1979 MGB is a overheating slug from the factory. A handful of aftermarket parts made/designed by people who were more than likely not trained engineers make them zippy, fun, and reliable cars so no more negativity please.
 

Ian0

Joined Aug 7, 2020
9,668
Shortbus..... The advance inside the distributor is tack welded in place because the timing curve is controlled by a computer with a vacuum adv. sensor. If I had the mechanical advance still functioning with the computer (no knock sensor) then it'd be running something like 60 degrees adv. at WOT and my engine would go boom. A 1979 MGB is a overheating slug from the factory. A handful of aftermarket parts made/designed by people who were more than likely not trained engineers make them zippy, fun, and reliable cars so no more negativity please.
This sounds like it is related to conversion to unleaded petrol. Knock sensors are there to extract the maximum performance from petrol with a lower octane rating, without them, you would have to accept much lower performance to stop preignition.
I was lucky to meet someone who races Sunbeam Alpines, and is an expert on cylinder head design. He could extract the same performance from unleaded petrol by reshaping the combustion chambers (and put the stellite valve seats in at the same time)
 

Thread Starter

MGPERF

Joined Jun 8, 2021
77
This sounds like it is related to conversion to unleaded petrol. Knock sensors are there to extract the maximum performance from petrol with a lower octane rating, without them, you would have to accept much lower performance to stop preignition.
I was lucky to meet someone who races Sunbeam Alpines, and is an expert on cylinder head design. He could extract the same performance from unleaded petrol by reshaping the combustion chambers (and put the stellite valve seats in at the same time)
I don't currently have problems with detonation but if I stepped up the 79 B to 10-5 compression I certainly would. If you have any details on reshaping the combustion chambers or pictures etc. please PM them to me I'd love to see it. I'm looking into ways to put a solid roller cam in the B. What an advantage that would be!
 

BobTPH

Joined Jun 5, 2013
8,813
Fascinating thread, I have no idea what anyone is talking about. Is there an “Engine Tuning For Dummies “ book?

Bob
 

shortbus

Joined Sep 30, 2009
10,045
Shortbus..... The advance inside the distributor is tack welded in place because the timing curve is controlled by a computer with a vacuum adv. sensor. If I had the mechanical advance still functioning with the computer (no knock sensor) then it'd be running something like 60 degrees adv. at WOT and my engine would go boom. A 1979 MGB is a overheating slug from the factory. A handful of aftermarket parts made/designed by people who were more than likely not trained engineers make them zippy, fun, and reliable cars so no more negativity please.
Why not mention ALL of what your doing or have done? Just from what you said in the post I quoted is what my response was based on.

I can't be like mrbill, that tells someone that has some weird ideas of doing something that all will be good, just keep up the good work. you haven't been here long enough to know mrbill is like a written Youtube video, not much sense. Just throwing things at a problem/ engine with no thought and understanding is fine with me if that is the way you want to go.
 

Ian0

Joined Aug 7, 2020
9,668
I saw that I guess I just don’t see the advantage of it vs. other CDI systems.
It's the original, because it's the patent. All the others will have been derived from it, usually changed just enough to avoid paying royalties.
The 1970 Wireless World circuit is lifted directly from the patent (I bet Mr. Winterburn didn't get his royalties!).
The ETI circuit is more sophisticated, with a regulated supply and a better points debounce. It also has a rather dodgy rev limiter which does so by causing misfiring and states "any backfiring will take place in the manifold and not in the silencer".
Winterburn used 200V on the capacitor, Wireless world made it a bit higher and ETI used 350V.
The supply is rated for 30W.
A 30W switched-mode running at 50kHz to 100kHz would be tiny by comparison (easily go on an ETD29 core, perhaps even an EF25).
It's basically a constant current circuit that switches off when the capacitor is charged so a UCC2808 would make a good job of it, probably a better job than the older SG3525 which doesn't have very clever current limiting.
One feature of all the designs is that they would probably blow up if the SCR fails to switch off.
 

MisterBill2

Joined Jan 23, 2018
18,175
Why not mention ALL of what your doing or have done? Just from what you said in the post I quoted is what my response was based on.

I can't be like mrbill, that tells someone that has some weird ideas of doing something that all will be good, just keep up the good work. you haven't been here long enough to know mrbill is like a written Youtube video, not much sense. Just throwing things at a problem/ engine with no thought and understanding is fine with me if that is the way you want to go.
That recent suggestion to an individual who keeps asserting that his beliefs are far different from what several have described as reality was my notice of abandonment from offering said individual any more advice. And when I offer a best guess, I qualify it as a best guess, not as a gospel truth. And I certainly try to avoid throwing stones.
 

shortbus

Joined Sep 30, 2009
10,045
If I had the mechanical advance still functioning with the computer
Is it considered negative to ask how your adding a computer into this engine? What are you using to pickup both the crank position and cam position? If this is a computerized engine why not go to individual coil near plug for the ignition?

You make statements but give no "meat" to the claims.
 

shortbus

Joined Sep 30, 2009
10,045
Having read that, I'd go for the optical system any day. It appears that the variable reluctance system gives a slopy waveform with no distinct edges that needs a comparator for reliable operation. If I need information on the rpm I'm much rather infer it from the time period between the pulses than try to determine it from the voltage from a reluctance sensor. What happens if the gaps vary? Or the magnetic field strength changes, or it gets rust particles in it? Seems like I might be better off adjusting the points.
It doesn't sell it to me!
so from that I get that you don't see reluctance sensors as reliable. What about all of the other places in a car that use them? Like VSS, anti lock brakes, cam and crank sensors? And like I said to the TS HEI modules can be used with points for ignitions that don't have a large enough distributor body.

That said CDI is not going to cure any of the problems of bad spark sequencing/correct timing. Will it give higher voltages to the plugs? Yes but not that much more than what a proper HEI module and the corresponding coil will give. And you can go into most any parts store in the world and get the parts to repair it.
 

shortbus

Joined Sep 30, 2009
10,045
That recent suggestion to an individual who keeps asserting that his beliefs are far different from what several have described as reality was my notice of abandonment from offering said individual any more advice
Doing that like you many times do is like being a test format Youtube video. You pat them on the back and say,"your on the right track, keep up the good work". When most times they aren't on the right track at all.
 

MisterBill2

Joined Jan 23, 2018
18,175
Certainly correct, at least for the CDI system that I used. Setting the correct time to fire is a separate issue from having enough fire every time. Competition requirements are quite different.
 
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