123 distributor temperature

[47silver]

Recently had a pertronix ignitor failure, I believe it was caused by heat in the engine bay of our 75 911s.

I was thinking of getting a 123 distributor but... now I am concerned about the ability of the unit to handle the heat as I have no desire to be stranded on a high speed highway in the middle of no where because of a transistor not being able to handle the temperature in the engine bay.

The 123 site shows a range from -30 to 100 °C , the engine oil temp and perhaps teh engine bay gets over 100C at times so this makes me wonder if it is going to last.

A set of points does not seem to be affected by the heat.

[mysocal911]

Originally Posted by 47silver

Recently had a pertronix ignitor failure, I believe it was caused by heat in the engine bay of our 75 911s.

I was thinking of getting a 123 distributor but... now I am concerned about the ability of the unit to handle the heat as I have no desire to be stranded on a high speed highway in the middle of no where because of a transistor not being able to handle the temperature in the engine bay.

The 123 site shows a range from -30 to 100 °C, the engine oil temp and perhaps teh engine bay gets over 100C at times so this makes me wonder if it is going to last.

A set of points does not seem to be affected by the heat.

Which is typically the case for a 911SC.

[spuggy]

Originally Posted by 47silver

the engine oil temp and perhaps teh engine bay gets over 100C at times

Based on my own datalogs, I would doubt the engine bay gets to 100C with the motor running, where are you getting that?

The big fan moves a lot of air...

If I switch off for 10 minutes (eg fill up) and hot restart, IAT spikes (to 50C or so) on re-start because the intercooler/engine bay heat-soaked from the motor/heat rising. It will return to ambient-ish (20-25C) within few minutes - like a block of driving or less - as hot air gets replaced, everything cools straight back down.

Even idling in road works waiting on a flagger, IATs never register more than a few, maybe 5C higher (although oil temp/CHTs climb noticeably higher than when you're moving - FMOCs no worky without airflow).

I've never seen the ECU (in the engine bay, where the CDI originally was) log an internal temp in excess of 50C, usually a lot lower, although it does generate its own heat (typically 10C over IAT/ambient).

This is a car that used to bake rear number plates a toasty brown color (discolored paint), before I fabbed a heat shield for the rear valance.

[mysocal911]

Originally Posted by spuggy

Based on my own datalogs, I would doubt the engine bay gets to 100C with the motor running, where are you getting that?

The big fan moves a lot of air...

If I switch off for 10 minutes (eg fill up) and hot restart, IAT spikes (to 50C or so) on re-start because the intercooler/engine bay heat-soaked from the motor/heat rising. It will return to ambient-ish (20-25C) within few minutes - like a block of driving or less - as hot air gets replaced, everything cools straight back down.

Even idling in road works waiting on a flagger, IATs never register more than a few, maybe 5C higher (although oil temp/CHTs climb noticeably higher than when you're moving - FMOCs no worky without airflow).

I've never seen the ECU (in the engine bay, where the CDI originally was) log an internal temp in excess of 50C, usually a lot lower, although it does generate its own heat (typically 10C over IAT/ambient).

This is a car that used to bake rear number plates a toasty brown color (discolored paint), before I fabbed a heat shield for the rear valance.

Right, not in the PNW. But here in SoCal, in some areas not far from the coast, 70C (160 F) in the engine compartment is common with the engine idling.
The late '80s turbos can get even hotter. So depending on the area in the summer, 100C is possible.

Read here (post #74) where the OP indicates a 911 3.2 engine at idle with a 210F (99C) temperature; Which way to turn 3.2 air flow disk?

Engine’s idling at 800 rpm and is at 210 dF.

[Nditiz1]

I have yet to hear anyone, anywhere complaining - bottom line, don't worry and go drive your car.

[mysocal911]

Originally Posted by Nditiz1

I have yet to hear anyone, anywhere complaining - bottom line, don't worry and go drive your car.

Remember, the earlier Porsche 911 (pre S/SC/3.2) engines with less HP (less energy loss = less heat) will have lower temps in the engine compartment.

[pmax]

Originally Posted by mysocal911

Right, not in the PNW. But here in SoCal, in some areas not far from the coast, 70C (160 F) in the engine compartment is common with the engine idling.
The late '80s turbos can get even hotter. So depending on the area in the summer, 100C is possible.

Read here (post #74) where the OP indicates a 911 3.2 engine at idle with a 210F (99C) temperature; Which way to turn 3.2 air flow disk?

Apples and oranges, mysocal911.

Spuggy's referencing the measured engine bay temp which is the salient point here. Makes sense that's lower than the internal.

If it's really 100C at the dizzy, I fear for the OP's internal magnesium parts.

[mysocal911]

Originally Posted by pmax

Apples and oranges, mysocal911.

Not really!

Originally Posted by pmax

Spuggy's referencing the measured engine bay temp which is the salient point here. Makes sense that's lower than the internal.

If it's really 100C at the dizzy, I fear for the OP's internal magnesium parts.

Yes, he's found and measured temps, in the PNW (typically temperate), in the engine compartment on the low side. That's the point!

Read the link I provided where the 911 3.2 owner measured 210F in the engine compartment. I've personally measured over 175F in the engine compartment while working on a 911SC idling in the summer.
A 911 3.2 will typically develop more engine heat, and a '87 turbo even more.

[icarp]

dave, STOP WITH YOUR GUESSING ,

YOU DON'T KNOW !

!@#$%

OP talk to some one who has one, a 123 dist

[mysocal911]

Originally Posted by icarp

dave, STOP WITH YOUR GUESSING ,

YOU DON'T KNOW !

!@#$%

OP talk to some one who has one, a 123 dist

The point being made in this thread is in reference to the engine compartment temperature and what temperature it can reach, as has been reported in other posts.
No comment was made about the 123 dist.

[spuggy]

Originally Posted by mysocal911

Right, not in the PNW. But here in SoCal, in some areas not far from the coast, 70C (160 F) in the engine compartment is common with the engine idling.
The late '80s turbos can get even hotter. So depending on the area in the summer, 100C is possible.

Not everywhere in the PNW is west of the Cascades. Where I live, we sometimes get verified (weather station) summer temperatures of 50C (120F). As well as 4 seasons, and occasional winter temps in the low teens...

I've logged CHTs in the MoTeC manager in excess of 250C idling on a hot day - in conjunction with much higher oil temperatures than I've ever seen with the car moving.

But when those temperatures were logged, the MoTeC in the engine bay (and, by extension, I'd presume most of the engine bay) was registering <50C. Because the fan moves a lot of air through the engine compartment.

Originally Posted by mysocal911

Read here (post #74) where the OP indicates a 911 3.2 engine at idle with a 210F (99C) temperature; Which way to turn 3.2 air flow disk?

Ah, the thread where you correct me for EEPROM - and then proceed to misquote capacity of a 2716 (2K x 8) or 2732 (4K x 8) EPROM by stating that they're 16 or 32 MB respectively, instead of 16 or 32K? I'd unsubb'd from the thread and hadn't noticed that before - LOL.


OP in that post says "Engine’s idling at 800 rpm and is at 210 dF." (sic).

Which is indicated temperature of the oil, - ie to demonstrate that the motor is at operating temperature. Most would regard that as "engine temperature".

Nowhere in that post, does he indicate the temperature of the engine bay itself.

Which, given your post of

Originally Posted by mysocal911

The point being made in this thread is in reference to the engine compartment temperature and what temperature it can reach, as has been reported in other posts.

seems spectacularly ironic - because no-one that I've seen on this board in 20 years has ever reported that their engine bay is at the same temperature as their oil.

[mysocal911]

Read post #8;

As per my post;

I've personally measured over 175F in the engine compartment while working on a 911SC idling in the summer.

If you question my data, find a 911SC idling for 30 minutes, with engine lid down, with the ambient temp at 95-100F, and measure the temp near the distributor.

If the OP is concerned about reliability, he needs to check his engine compartment temp for a worst case temp, and then call the 123dist tech support if he's concerned.

[h20cycle]

Apologies if I missed it but is the consensus here that 123 distributors work well with no indication of functional issues due to engine bay temps?

[panama911]

No ;-)

The distributor in a 911 indeed can get pretty hot, hotter than engine bay ambient temperature and there are reports of 123-dizzys failing at high temperatures (track use, german weather not SoCal).

BUT - these reports I know of are from a few years back... maybe they improved or fixed it by now? I don't know...

P.S.: Pertronix Ignitor with HKZ seems to work fine if you don't want points...

[Nditiz1]

@panama911 - can you link your sources stating that the high temperatures were the cause of the failures?

[panama911]

Sorry, no link - my sources are guys who run their old 911s on trackdays like on Nuerburgring, Spa, Salzburgring... but again, that was some years ago.
Personally, I'm running an original Bosch with Pertronix without issues - but then, my car is a targa not a racecar :-)

[icarp]

To all that are interested.
Some testing for temps in engine bay , more to follow


WeI did some engine bay temp measurements.
Thermo couple for data. When running the engine bay was 20-25 degF above ambient. After park it peaked about 45 deg F above ambient.
97 f degrees ambient. I think there is enough margin to mount ECU in engine bay as long as we use standoffs so that airflow can hit 6 sides.
As The ECU requires a max temp of 180f.
We have another data log from an EMU Black
I will convert the file and post numbers
Back in the olden days we used to run isolated thermometers for data , if you dont know then you dont know. Guessing at data is BS
Stop with your guessing and gather data

[icarp]

“If the OP is concerned about reliability, he needs to check his engine compartment temp for a worst case temp, and then call the 123dist tech support if he's concerned.“

I am the tech master for 123 ignition

Stop guessing

[mysocal911]

Originally Posted by icarp

“If the OP is concerned about reliability, he needs to check his engine compartment temp for a worst case temp, and then call the 123dist tech support if he's concerned.“

I am the tech master for 123 ignition

Stop guessing

Actually, the more appropriate problematic temperature should be evaluated on the engine case where the distributor is mounted and not just in the engine compartment, which will be significantly cooler.
Furthermore, the engine temperature will be hotter than the oil temperature. So if the oil temp gauge provides an actual oil temp value, one can easily assume that the engine case has an even higher temp value.

[Nditiz1]

Why are we speculating about what the temperatures are. Without any real data we are just guessing. I am running the 123 in all my 911's. I have yet to see any issues with 95+ F ambient temps running oil temps at 210F. Running sustained at those temps for a couple hours with no issues. If the OP is concerned, reach out to the tech master. Unless you have factual sources of data then no need to reach up from your desk chair and just scroll on.