Fun with troubleshooting leanness (and 5th gear cruising temps) Options

[emerygt350]

Oh my! The plug looks great! Maybe this explains why Porsche didn't just tune the 2.0 in 73 with only the MPS and instead added the washer and the extra resistance when they still used the 1.7 computer. Just tuning the mps alone maybe won't get you there.

[Superhawk996]

(IMG:style_emoticons/default/smilie_pokal.gif) I like the creativity

[technicalninja]

On L-jet crap I'll added variable ratio potentiometers on both the CTS (your CHT) and IAT circuits.

Big changes with CTS and small adjustments with IAT.

I'd adjust till a bit on the rich side and then lean out with small adjustments with the airflow meter spring tension.

With patients and practice I could dial in a L-jet powered 280Z pretty close...

I know you're D-jet and it's different.

Don't know if you're even using an IAT but it works the same way...

Used to buy the little puppies at Radio Shack for less than $5!

[emerygt350]

I miss radio shack... What a loss to all tinkerers.

[Shivers]

I miss radio shack... What a loss to all tinkerers.

I think the same thing everytime I drive By the Weed Grass healthfood place where the RS used to be. (IMG:style_emoticons/default/sad.gif)

[r_towle]

You are somehow tuning the vacuum advance and monitoring that?
Please explain more…..

Rich

[emerygt350]

No, I have a 123, old school, no Bluetooth. I was just turning it on and off remotely while driving by blocking the ported vacuum to the dizzy. I was then watching cruise vacuum level, AFR, and cylinder head temps.

[DRPHIL914]

hey there , am following your testing on ths and curious about your results, because i have a similar issue and similar set up. my rebuild is also using a similar cam, d-jet, a 123ignition distributor, and also the motor seems to really run well with more advance and the 93 octane. i think i am at 30 degrees advance at 3400rpm(set using stock recommended method.) and wondered well if i back off to the stock advance in timing, this would probably help head temps but if i remember when i put that in a couple years ago, it hurt performance but didnthelp head temps that much. I run no vac or retard hoses on the dizzy, i could never get a good proper rpm at idle set up like that.

i also have a bored out throttle body bored to 50mm, stock air cleaner.
compression is 9.5, these are new heads new P&C's, etc, SSHE and SS muffler from Ben.
i bumped my fuel pressure up to 32, it likes that, and my A/F readings are really good, but still on highway cruising at 75mph i am at about 3400-3500 rpm i think and get great milage and the A/F says 13.5,oil temps perfect but head temps will go slowly up and get up around 330-350 and if i am pusshing up a hill or something then they go up more,
I added a rheostat to my CHT and settled to around 1000 ohms, - all temps are fine otherwise, and i felt like maybe this is due tojust not enough airflow over the #3 head,
i wonder if they have this issue with the set up they are developing at PMB for this same motor configuration.
BTW if i cruise in 4th gear at about 3400rpm head temps drop to just under 300, that isa bout 60-65mph give or take, so why? less heat production?

i like to take longer drives but cant cruise on the interstate witough watching my head temps and worrying about seeing that read out of the AFR being around 340-350.

Phil

[emerygt350]

I would love to hear how PMB handles it but I suspect with a good cam grind most of this goes away. At least that is what I have heard. I have the stock cam.
djet, original 2.0 heads, 96mm piston/sleaves, 123 non-bluetooth dizzy. Mine is a little warmer than yours. Mathematically I was shooting for 8.5 compression but I suspect I am closer to 9. I suspect the combustion chamber was a little smaller than my measurements (oil and clay both).

And yes, a couple degrees advanced is where it likes it, and the impact of reducing the advance is quite a performance hit (I will have hard data on that once I get to the Dyno) with little effect on temps at cruise. Right now I am at 8.5-9 (at 950rpm) so about 30 at 3400 (how accurate can we possibly be?). Idle for me is very good though, not sure why that would vary much, I do notice idle is terrible at 7 (at 950rpm), inconsistent, engine rpm dropping too low frequently etc but a soft landing would idle ok. That is with tuning the ecu and idle control etc.

Apparently around 330-350 is where these heads like to be if I remember correctly, so anything around there doesn't bother me. It's when it climbs past 380 that I get a little nervous, and mine will do that in 5th cruising at 72 on a pretty relaxed incline if given enough time. Town driving 280-300 depending on ambient temps. Oil is nice and cool (180-200). Even 60 in 5th (which I know many people don't do) is getting there near 360 at level cruise over long periods. I took it through the twisty's yesterday pushing it real hard and the engine never got over 314. My son was asking me why they just didn't make the fan go faster on the highway, so we had a discussion about physics....

Also, the seating of the ring on that 3rd plug really matters on what temperature you get on the gauge.

[DRPHIL914]

I would love to hear how PMB handles it but I suspect with a good cam grind most of this goes away. At least that is what I have heard. I have the stock cam.
djet, original 2.0 heads, 96mm piston/sleaves, 123 non-bluetooth dizzy. Mine is a little warmer than yours. Mathematically I was shooting for 8.5 compression but I suspect I am closer to 9. I suspect the combustion chamber was a little smaller than my measurements (oil and clay both).

And yes, a couple degrees advanced is where it likes it, and the impact of reducing the advance is quite a performance hit (I will have hard data on that once I get to the Dyno) with little effect on temps at cruise. Right now I am at 8.5-9 (at 950rpm) so about 30 at 3400 (how accurate can we possibly be?). Idle for me is very good though, not sure why that would vary much, I do notice idle is terrible at 7 (at 950rpm), inconsistent, engine rpm dropping too low frequently etc but a soft landing would idle ok. That is with tuning the ecu and idle control etc.

Apparently around 330-350 is where these heads like to be if I remember correctly, so anything around there doesn't bother me. It's when it climbs past 380 that I get a little nervous, and mine will do that in 5th cruising at 72 on a pretty relaxed incline if given enough time. Town driving 280-300 depending on ambient temps. Oil is nice and cool (180-200). Even 60 in 5th (which I know many people don't do) is getting there near 360 at level cruise over long periods. I took it through the twisty's yesterday pushing it real hard and the engine never got over 314. My son was asking me why they just didn't make the fan go faster on the highway, so we had a discussion about physics....

Also, the seating of the ring on that 3rd plug really matters on what temperature you get on the gauge.

interesting, we're not far off of each other, my cam is same grind as LN cam for a 2056, and i also do start to push temps up toward 370 at times, and it does like to cruise at about 80 smooth and stil under 4000rpm it runs so good i woud just dive that fast if temps didnt go over 350 but they do. and like you pushing hard in themountains and twisties, or A/X run and no temp issue then. or even idling its fine. and idling,and oil temps are no issue at all, but maybe the oil needs to be pullling more heat from the motor. my A/F is about 13 on idle, 13.2-13.7 at cruise and 12-12.5 on WOT , so i think those numbers are pretty good. it was cooler yesterday abou 60 degrees and driving home from porsche club cruise out to an airport for a cuise in and fly in event, i took more back roads but during the 70 mile trip i only spent about 30 miles on the interstate, andduring that time i was seeing 330-360 depending on my speed which was between 68-75. Motor now has about 6k miles since the build.

btw what PMB is doing is using holly terminator x as the ECU, running 40psi for fuel pressure and GM injectors, either in with stock d-jet set up or using ITB's from Jenvey
. i have to ask Eric how thats working with regard to motor head temps. thats what they are putting on their motors from 2056 up to the 2.4's they are buiding.

[emerygt350]

I would love to hear how PMB handles it but I suspect with a good cam grind most of this goes away. At least that is what I have heard. I have the stock cam.
djet, original 2.0 heads, 96mm piston/sleaves, 123 non-bluetooth dizzy. Mine is a little warmer than yours. Mathematically I was shooting for 8.5 compression but I suspect I am closer to 9. I suspect the combustion chamber was a little smaller than my measurements (oil and clay both).

And yes, a couple degrees advanced is where it likes it, and the impact of reducing the advance is quite a performance hit (I will have hard data on that once I get to the Dyno) with little effect on temps at cruise. Right now I am at 8.5-9 (at 950rpm) so about 30 at 3400 (how accurate can we possibly be?). Idle for me is very good though, not sure why that would vary much, I do notice idle is terrible at 7 (at 950rpm), inconsistent, engine rpm dropping too low frequently etc but a soft landing would idle ok. That is with tuning the ecu and idle control etc.

Apparently around 330-350 is where these heads like to be if I remember correctly, so anything around there doesn't bother me. It's when it climbs past 380 that I get a little nervous, and mine will do that in 5th cruising at 72 on a pretty relaxed incline if given enough time. Town driving 280-300 depending on ambient temps. Oil is nice and cool (180-200). Even 60 in 5th (which I know many people don't do) is getting there near 360 at level cruise over long periods. I took it through the twisty's yesterday pushing it real hard and the engine never got over 314. My son was asking me why they just didn't make the fan go faster on the highway, so we had a discussion about physics....

Also, the seating of the ring on that 3rd plug really matters on what temperature you get on the gauge.

interesting, we're not far off of each other, my cam is same grind as LN cam for a 2056, and i also do start to push temps up toward 370 at times, and it does like to cruise at about 80 smooth and stil under 4000rpm it runs so good i woud just dive that fast if temps didnt go over 350 but they do. and like you pushing hard in themountains and twisties, or A/X run and no temp issue then. or even idling its fine. and idling,and oil temps are no issue at all, but maybe the oil needs to be pullling more heat from the motor. my A/F is about 13 on idle, 13.2-13.7 at cruise and 12-12.5 on WOT , so i think those numbers are pretty good. it was cooler yesterday abou 60 degrees and driving home from porsche club cruise out to an airport for a cuise in and fly in event, i took more back roads but during the 70 mile trip i only spent about 30 miles on the interstate, andduring that time i was seeing 330-360 depending on my speed which was between 68-75. Motor now has about 6k miles since the build.

btw what PMB is doing is using holly terminator x as the ECU, running 40psi for fuel pressure and GM injectors, either in with stock d-jet set up or using ITB's from Jenvey
. i have to ask Eric how thats working with regard to motor head temps. thats what they are putting on their motors from 2056 up to the 2.4's they are buiding.

That is probably what any sane person would do bumping the power like this. I just emailed the Dyno, hopefully I can get in soon, it will be interesting to see what kind of change I see. Sadly I didn't do a cruise pull before the rebuild but I have all the numbers for the WOT pull pre 2056.

[emerygt350]

Sooooo.... Got to the Dyno yesterday (Easter miracle). Some kind of rf interference caused his equipment to malfunction (474 foot pounds of torque?). However, we were able to work on the mix. I am now back to nothing but the 250 ohm resistance that the car originally had from the factory. I was so rich his equipment didn't go that low. We did some cruise at speed tests on the Dyno and made sure my AFR was healthy under all conditions.

That smoothed out the curves, and we bumped it to 29 degrees at 3400, which improved the imaginary numbers over 3k quite a bit.

He suggested experimenting with higher octane. I put some octane booster in it today and it seemed to make a significant difference at cruise. I am keeping my fat switch though, I have an extra 100ohm resistor I can activate at will. That richens it nearly a whole point. Just in case.

Anyone ever notice if the Dakota digital cht is sensitive to voltage? My regulator was misbehaving (14+ volts). Replaced it today with an adjustable solid state. Have not driven it yet however.

[Porschef]

That smoothed out the curves, and we bumped it to 29 degrees at 3400, which improved the imaginary numbers over 3k quite a bit.

[That’s where I have mine set, I believe that is the typical setting.]

He suggested experimenting with higher octane. I put some octane booster in it today and it seemed to make a significant difference at cruise. I am keeping my fat switch though, I have an extra 100ohm resistor I can activate at will. That richens it nearly a whole point. Just in case.

[I usually run 87 until the weather gets hot, then 89. Never seemed to see the benefit from 93]

Anyone ever notice if the Dakota digital cht is sensitive to voltage? My regulator was misbehaving (14+ volts). Replaced it today with an adjustable solid state. Have not driven it yet however.

The Dakota unit seems to be unaffected by what is usually slightly lower voltage in my car, it typically runs at just under 13V

If you really want to improve the shifting, spring for the Tangerine firewall bushing. I’m sure you got a big improvement with the factory style bushing, but Chris’ product really made a major difference

[Superhawk996]

Sooooo.... Got to the Dyno yesterday (Easter miracle). Some kind of rf interference caused his equipment to malfunction

Could it have been your car with its old school unsuppressed ignition system?

Did the problem only exist then your car was runnning?

[emerygt350]

Sooooo.... Got to the Dyno yesterday (Easter miracle). Some kind of rf interference caused his equipment to malfunction

Could it have been your car with its old school unsuppressed ignition system?

Did the problem only exist then your car was runnning?

Yes, only when running, but I had it on his dyno a couple years ago before the 123ignition dizzy. It is a pertronix coil at the moment. I was suspecting the failing voltage regulator and now I wonder if the super cheap chinese bluetooth radio I installed might have been the culprit. Although that would have made a mess of things with the ignition on engine not running, which wasn't the case.

[Superhawk996]

Two things likely contributing to ignition related RF.

1) Pertronix coil is lower resistance than a Bosch blue coil - therefore generates more RF.
2) 123 dizzy uses electronic switching which is almost instantaneous off/on vs mechanical points switching. This too increases RF.

To reduce RF at the source:
Spiral wound spark plug wires
Resister plugs
Go back to Blue Coil

These are the quick go to solutions.

He could also shield his torque sensor and instrumentation wiring as another option that might help

[emerygt350]

Two things likely contributing to ignition related RF.

1) Pertronix coil is lower resistance than a Bosch blue coil - therefore generates more RF.
2) 123 dizzy uses electronic switching which is almost instantaneous off/on vs mechanical points switching. This too increases RF.

To reduce RF at the source:
Spiral wound spark plug wires
Resister plugs
Go back to Blue Coil

These are the quick go to solutions.

He could also shield his torque sensor and instrumentation wiring as another option that might help

I have the bosch coil sitting there, I was trouble shooting with the pertronix. I will go back (I like the look of it).

[Superhawk996]

I have the bosch coil sitting there, I was trouble shooting with the pertronix. I will go back (I like the look of it).

Double check me. Bosch blue should be 3-4 ohms on primary. If I’m not mistaken Pertronix is more like 1.5 or two.

[emerygt350]

I have the bosch coil sitting there, I was trouble shooting with the pertronix. I will go back (I like the look of it).

Double check me. Bosch blue should be 3-4 ohms on primary. If I’m not mistaken Pertronix is more like 1.5 or two.

The Bosch I have is the one needed for the 123injection. I checked the pertromix as well to make sure I wouldn't fry the dizzy. I can't remember anymore what the value is but I think they were both the same. I can look after the rain stops.

[era vulgaris]

Yeah, the only place where I have an issue is 5th gear interstate travel. Racing it stays nice and cool. I may just have to make some kind of fudge for that and stop worrying about it.

5th gear interstate travel is always going to run hotter than lower gears below ~65mph. Around roughly 65mph is where air resistance begins to become a factor on the load the engine sees, and the faster you go above 65mph, the more load the air resistance and drag will be putting on the engine.

I used to run a 4 channel digital CHT gauge designed for light aircraft on a 2270 type 4 running dual DRLA40's, tuned to keep AFR in the mid-to-high 12's at cruise (this is where I got the lowest head temps). #3 CHT in gears 1-4 running around town, cruising in the 3k-3.5k rpm range, was low 300's, like 315-320 area. Cruising above 70mph in 5th (same rpm range) with the top on and windows closed was like 350. Windows open it was a little higher due to increased drag. But with the windows down and top off on the interstate it was even higher, like 365-ish area, because with the top off at those speeds the car's aerodynamics basically turn into a parachute that the engine has to fight against. Notably, below 65mph having the top on or off made no difference in head temps because the drag it creates at those lower speeds isn't enough to impact the load on the engine.

As long as head temps keep steady and don't creep upwards continually, then I don't think there's much to be done about this. I took multiple 3+ hour trips on the interstate, and head temps always stayed rock solid steady at the above numbers, and would come back down to the off-highway numbers once off the interstate.