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

[emerygt350]

So I have been playing with adding resistance to the cht to bump my mixture. Messing with the mps was not getting me to where I wanted to be I wanted something a little more global. Anyway, bought a 10 dollar Bluetooth relay. Set it up so one channel was clean the other had 50ohms resistance in it. As I am driving I can switch back and forth and watch the results on the cht and AFR. 50 is really working well (this is all in addition to my 250ohm found on 73s). Now I have added another 20 ohms to the alternate so the relay will switch between 50 and 70. It ain't pretty but it's only for troubleshooting.

[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.