ECU P4120534 Super Stock / Pro Stock / Nascar

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I think it had something to do with the coil used. mom not completely sure though.


I wish I could find the coil that came with it. The distributor and box were together. So my guess is my cousin sold it.

Also, I posted pictures of the rocker shafts in the other thread.
 
View attachment 1715477629 View attachment 1715477630 View attachment 1715477631 All right. Here are the pictures of the gold box I have. I thought there was a part number on it. There isn't. But I did research the best sink on it, and I believe this is the 1980's gold race box.

I also know this was used on a street/strip car. I also know I've personally tested it, and it's only losing 1 degree across 10,000 RPM. I also ran it to 12k and it didn't lose any more.

IMO, even this box is usable for a street/strip car. Regardless of what Chrylser said at the time.

The picture is clear now. The “racing” combination of a hot, low resistance Coil with a .25 Ballast. The ECU is getting approx. twice the amps of a typical “Street” combination: ECU spec of 4-5 amps max.

So with a Coil/Ballast setup that would provide approx. 3 ohms of resistance, the “racing” ECU’s would probably be quite happy in street driven cars. Likely would last forever.
 
The 534 ECU, .25 Ballast, less the T-drive dist and wiring (in use) that came in my distributor kit back in the '80s. The 306 coil was a separate purchase from kit.............
View attachment 1715476301View attachment 1715476305


I just picked up this same Chrome ECU without the P before part number
Same Britain Transistor

$20 brand new never installed at a swap meet Mopars In The Park

I also still have my Mopar Performance P part number chrome box on the shelf

So where saying there is a difference in operation between the two exact same part numbers other then a P on a stamp ?
 
....So where saying there is a difference in operation between the two exact same part numbers other then a P on a stamp ?

I'm thinking they are the same. But to answer this definitively one would need to be the design engineer. For all I know the "P" prefix possibly sold as the stand alone over the counter and mine is the package version. Could also signal a change in who manufactured it or a revision of it.
The take I have has to do with the combination of parts used. The "race" combination (coil, resistor, ECU as a team) for higher output likely causes the ECU to heat more so extended run time may take a toll on the ECU life.
 
I've NO IDEA on the ECU differences, but from what the parts guys at Dodge store told me, the P preceding the part number is for Mopar Performance. I know the MP catalog I have states "race application " only for the chrome box.
 
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ecu III.png
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Steve tons of differences. I have been testing them on the distributor machine in a mock up with a scope. Specs are pretty much as stated, obviously I dont have all the numbers and a matched ballast resistor value does make a huge difference in performance. Go with the rated one for the most performance.
 
I believe "P" was being incorporated in PN's around '70/'71 in the "Hustle Stuff" days, back when I was hustling newspapers from a delivery bike before school. :D
 
I don't know when the "P-Part" numbering began. Or whether it was always put on the parts themselves. We could look inthe HH Library at the early catalogs.
 
Some of the camshafts in the 1971 Hustle Stuff Catalog have a P.
The 1970 Hamtramck Registry - 1971 Chrysler Hustle Stuff (Pg 2)

The 1973 Mopar Special Parts book has this on the first page
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It too has a mix of P-parts and non P parts includingthe electrical and ignition parts.
1973 Mopar Special Parts page 2-5
I always had assumed the P-part designation was for manufactuing and inventory purposes.
But it may be that the initial reason was exactly what is stated on the first page, to identify parts that are for racing/off-road use.
For example in the cooling parts there is a non P part aluminum fan. Is that a production fan? I don't know. The non-p part viscous fan on the same page probably is a production part. We can go look them up.
1973 Mopar Special Parts page 2-4
 
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I always though this was the gold box...I bought one a long time ago with 'Mopar' on it and it even had the common 5 point ECU plug on it. I guess that was just a contract built MSD-7 with a mopar suffix.
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I'm thinking they are the same. But to answer this definitively one would need to be the design engineer. For all I know the "P" prefix possibly sold as the stand alone over the counter and mine is the package version. Could also signal a change in who manufactured it or a revision of it.
The take I have has to do with the combination of parts used. The "race" combination (coil, resistor, ECU as a team) for higher output likely causes the ECU to heat more so extended run time may take a toll on the ECU life.

Yes that was the conclusion we came too in the original go round on this thread. An Coil/Ballast ignition system with 3.0 resistance would provide sufficient resistance such that the "racing only" 534 would be happy on the street. They are robust units and with that combination would probably run forever.
 
7175B18A-BABB-467A-B6F3-07E2FF434D20.jpeg
I wish I could find the coil that came with it. The distributor and box were together. So my guess is my cousin sold it.

Also, I posted pictures of the rocker shafts in the other thread.
Race coil P3690560 is the same as Accel 140306

Here are the specs on that coil if you want to look for something new

7175B18A-BABB-467A-B6F3-07E2FF434D20.jpeg
 
The "P" designation was on all Direct Connection and Mopar Performance parts. I believe it started with Hustle Stuff. It was to differentiate DC parts from the other parts and likely just stands for performance...
 
1974 Part # 3755500 Chrysler ECU - Black with Blue heat sink
RCA Transister
Can’t find any info on this one ??? Anyone

I know Chrysler had a Factory Part # 3755550 used on cars


Thanx Scott
 
The ECU spec chart I copied to this thread was submitted by @halifaxhops in another thread. Unquestionably a knowledgeable guy. I was surprised to see that there were several types of “Chrome Boxes” listed there. Only one recommended as suitable for street applications (Chrome/Blue NO fins).

So I gathered that one has to be careful about the generic term “Chrome Box”. I do like the chrome case but apparently there is more to it than just pretty. So I checked out my chrome spare. Turned out to be the Chrome/Black P4120534 (racing applications).

@yellow rose has one he has tested. His comment is above in this thread and does prove the spec to be accurate.

I’ll be buying a standard street use application ECU to replace my spare.

If anyone chimes in that is happily (long term?) using a P4120534 ECU in their street driven car I would appreciate knowing what the coil/ballast combination being used is.

Thanks to all who have commented.
What did you find out ?? what ended up working for you long term... the orange or chrome box?
 
What did you find out ?? what ended up working for you long term... the orange or chrome box?
I never did install it. The selling price of the "534" ECU has risen dramatically in the last couple of years. $250 ++ today. It's sitting on the shelf. It's an investment! LOL!
 
I never did install it. The selling price of the "534" ECU has risen dramatically in the last couple of years. $250 ++ today. It's sitting on the shelf. It's an investment! LOL!
Yep good investment I should have picked up a couple of spares back in the days to have..
 
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