[Joshboody]

Originally Posted by roninsoldier83

The biggest advantage you're going to see by running lower cylinder pressures
on the compression stroke is knock resistance. Simply put, compression = friction, and friction = heat. The higher your cylinder temperatures are, the more unstable/combustible the mixture (A:F) is going to be, which decreases your margin for error in relation to the knock threshold.

EGT is an animal of it's own.... excessive timing retard can raise EGT's, same thing goes for running excessively rich, it can raise EGT's (both cases fuel is still "burning" as it's exiting the exhaust valve). In contrast, I've seen reductions in EGT due to knock/detonation (more heat absorbed by the combustion chamber). However many times EGT and knock resistance are mutually exclusive, i.e. you can retard timing & run rich which will raise EGT's without any presence of knock. EGT is a topic all to itself, I merely mentioned it above as a way to reflect measured decreases in cylinder temperatures without changing tuning parameters (i.e. fuel, timing or boost) that could easily alter EGT, in order to quantify "gains" in efficiency through exhaust modifications (i.e. helping our motors/air pumps flow air/breathe more efficiently).

thanks for all your comprehensive replies. I had a flaw in my thinking above and not factoring the increase in burn rate with higher compression.

[enrita]

Originally Posted by roninsoldier83

Higher cylinder temps result in a more unstable/combustible mixture, the mixture is comprised of air and fuel (the two elements that are being compressed). Cylinder temps don't modify the AFR (the ratio of air to fuel is still the same) they just make the mixture of the two more combustible/unstable.

Hope that makes sense to you.

would that occur across the power band or more pronounced down low or higher up ?

[mtlr]

Originally Posted by roninsoldier83

Higher cylinder temps result in a more unstable/combustible mixture, the mixture is comprised of air and fuel (the two elements that are being compressed). Cylinder temps don't modify the AFR (the ratio of air to fuel is still the same) they just make the mixture of the two more combustible/unstable.

Hope that makes sense to you.

I guess you mean the fuel is closer to its autoignition temperature hence more unstable/reactive?

Makes sense.

[Litos]

Originally Posted by JPSlick

So you have BOG in an automatic car? Send a Log to Terry.

well, the car shifts slowly in all gears.

it just may be the fact that i'm comparing it to my SRT8.

my SRT8 barks the heavy ass 22's into second gear without batting an eye.

[roninsoldier83]

Originally Posted by enrita

would that occur across the power band or more pronounced down low or higher up ?

Typically you find higher cylinder pressures/temps as engine speed increases (with all other factors being equal). Which is one of the reasons you see a lot of tuners (as well as OEM's) taper the AFR a little richer up top, in order to use fuel to help combat high cylinder temps/stave off detonation.

[roninsoldier83]

Originally Posted by mtlr

I guess you mean the fuel is closer to its autoignition temperature hence more unstable/reactive?

Makes sense.

Yes sir, you got it

[enrita]

Originally Posted by roninsoldier83

Typically you find higher cylinder pressures/temps as engine speed increases (with all other factors being equal). Which is one of the reasons you see a lot of tuners (as well as OEM's) taper the AFR a little richer up top, in order to use fuel to help combat high cylinder temps/stave off detonation.

thanks!

[Jeff@TopGearSolutions]

Originally Posted by Litos

well, the car shifts slowly in all gears.

it just may be the fact that i'm comparing it to my SRT8.

my SRT8 barks the heavy ass 22's into second gear without batting an eye.

How does it shift on map 0 or completely stock no tune installed?

[Litos]

Originally Posted by JPSlick

How does it shift on map 0 or completely stock no tune installed?

the same. it just feels laggy compared to my SRT8.

i increased shift functions on the DiabloSport so it hits hard and fast.

[Litos]

but the SRT8 lagged a little when it was stock also - just not as laggy

[bigdaddycane]

roninsoldier,

Have you sent these to Terry? any comments?

Like you I came from the JB3, but did not data log with the 3. Now with the JB4 I ran Map 1 and didn't really feel the punch of Map 3 on the JB3. Switched to Map 5 and it feels better. I'm looking to see what others are seeing / feeling with the new software.

BTW I will be datalogging on Map 5 this week as well.

[roninsoldier83]

Originally Posted by bigdaddycane

roninsoldier,

Have you sent these to Terry? any comments?

Like you I came from the JB3, but did not data log with the 3. Now with the JB4 I ran Map 1 and didn't really feel the punch of Map 3 on the JB3. Switched to Map 5 and it feels better. I'm looking to see what others are seeing / feeling with the new software.

BTW I will be datalogging on Map 5 this week as well.

I sent Terry a link to this thread, but no I merely eyeballed the graphs and saved them as jpegs rather than saving all csv values, so I haven't sent him full text value/csv logs, but he has seen the graphs. After a week of driving, I'll be shooting him full csv logs from the dyno on Saturday.

We chatted about it a bit, but mostly Terry said it looked like autotuning was doing its job (I agree, only had it in for ~24 hours, and it was progressively lowering boost with each pull). Although he reserved a bit of judgement due to not seeing full text value logs. We chatted a bit about their new CPS offsetting module among other things.... in truth, in a back and forth conversation scenario, I am notorious for going WAY off-topic haha, so much of our conversation wasn't about these quick logs specifically.