duration/fuel pressure actual ?'s

[olboyowl]

what is the highest duration should be set at? i don't know how much is to much. i know adam mentioned in another thread about to much duration would cause the injector spray pattern to start firing outside of the piston bowl. im currently at 3100us with no smoke (which isn't a problem) and my egt's aren't getting over 1400*. can i keep adding? my fuel pressure question is, what is the lowest psi u want to see the fuel pressure actual falls off to when logging. mine drops to 20,600 psi and desired is at 22,xxx between roughly 2100-2500 rpm. pump picks up and runs fine after the initial pressure drop. any help would be appreciated. thanks

denny

[AdamRRT]

You'll be able to tell max duration on the dyno usually. Given that you have a set maximum timing start degree, you'll get to a point of rapidly diminishing return where the piston is moving downward nearly as rapidly as the compression is chasing it, resulting in minimal if any power gain for the added duration. Typically accompanied by increased EGT, but not necessarily if you're just barely to that point.

What we really just need to have eventually is someone make a table showing the safe start BTDC and end ATDC degrees for timing, based upon RPM. I don't have that knowledge, but some guys might be able to help. If not, give it time. Hang tight, and be safe for now until somebody gets time enough to share what they've found on that. It'll probably be a matter of gathering info on how much timing guys have ran without problems, and organizing the data from there.

But it will also depend upon the volume of fuel leaving the injector. So rail pressure and injector nozzle size will matter to a degree, I believe. Although I could also be wrong on that.

[Dmaxink]

it is still to early to tell...i can tell you i didnt see any gain on the dyno above 3300uS...and timing i didnt see any gain over 32 if i rem correct. ATDC limit will consist of watching egts and what your comfortable with... BTDC limit is at to what point did a guy get rattle/ what quit making power.. In a nutshell every truck is different and there is no knowledgebase that fits all... I say spend a few bucks at your trusted dyno and learn that way... I'm not going to lie when you spend thousands on dyno bills it isnt easy to just be nice and throw everything spent from our hard earned cash out there into the public this early on in development... not only that but there hasnt been any failures yet with different calibrations..so how can we assume a hard limit when there isnt one set yet? No one can say "well my smarty broke at X" because smarty sucks and didnt do what was commanded anyways...lol the best way to answer these questions is to spend a few bucks on the dyno and then contribute your findings to the community... I mean here we are in dmax world years later and still what constituted as a failure is kept hush hush... not from everyone.. but many. Just my .02

[AdamRRT]

But won't the tuners have their dyno info to tell?
It's not like safety info is going to cost them any business.

I just can't imagine such a thought of "well I spent the money on it". We spend because we're willing to part with the money. Not sharing the findings does nothing to reverse the clock and get that money back.

[comnrailpwr]

I agree that findings of an individual truck on a dyno will be good information for the OWNER of that truck in regards to safe maximum duration and fp.

On that note its is indeed truck specific and based on engine build. If someone of a modified truck posted his safe maximums then i feel it is quite likely misleading information to someone of another truck, even if the build would be the same. Only way I see it beneficial is if builds are the same with the same manufacturers parts and the truck owners reside at the same altitude and climate. variables are still at play tho. Basically I feel if u had this information then is should be said like this: MY trucks maximum safe duration is xxxx uS and my safe FP is xx,xxx PSI. My climate is xxx and altitude is xxx. My engine modifications are..........

I feel the only way for this info to be valuable from one truck owner to another is if the trucks were both bone stock. Even then there are still variables to consider. (Parts are not created exactly equal) In my opinion only way to know is put the truck on a dyno to get your specific information.

Jake

[AdamRRT]

Not at all. That's taking the details to an extreme. You can get a rough idea. That's all it'll be and that's still a huge help. Of course every vehicle is different. But you can still gather the info over time, giving you a general idea of what is and isn't safe. If we get to the point that we see a pattern of burned pistons happening at or near X*, we know to not go there unless we accept the added risk.

It becomes a point of using your noggin to decide how you will deal with the data. Seems simple. We do it in all our daily activities already. It applies in all aspects of everything we do. No reason to not apply it here. Surely nobody thinks they'll ever get hard and fast rules about tuning. If so, they need to sell EFILIVE and go back to their Smarty.

[comnrailpwr]

Ya I'm with ya Adam for a general idea or general range. I was referring to individual safe MAXIMUM's, for that data a dyno is needed

Jake

[2007 5.9]

My highest PW ocours at 160MPa and is 3100pw

~Les

[olboyowl]

thanks for the info guys. kory, i wasn't askin for a personal set up or anything. i understand were your coming from with the money u spent to get to were your at. at the same time, the only way were goin to advance is help each other. you and several others have givin me some dam good info to get me were im at now and i thank yall for that. just tryin to see what u guys that have had the dyno times results have been. im not changing anything major until i get the truck on the dyno (hopefully this weekend unless the wife has our first kid...). my set up is 45* (25*) main timing, 3150us, 160 mpa. from 60-110mph, it runs just about perfect fp a/d 160mpa, 1400*egts and hardly no smoke. again, thanks to all who helped get me lined out. will get back with more info. take it easy

denny

[Dmaxink]

I reread my post and it sounds like I was being a dick...lol... that's the case of reading something and not hearing the way I was meaning it to be expressed! Anyways, what I was trying to say was at this point in the game all we can do to help each other is everyone get some dyno time and see what works best..where things quit making power...and maybe in a few months..see what caused a failure :-)....cause as it stands..none of us know what will cause one yet as we can only go off theory... I can tell u one of our dodges that runs mid 12s tune-trans-lift pump only is running 3250uS and 31* timing and 180mpa... he has been running this since day 1 of me being able to tune these things and he knows where we stand with this as being too early to know real limits.