14 replies to this topic

[lanceschallenger]

Okay guys, I need some information about the igniton timing in the 5.7? How do the two numbers corillate and what is WOT timing on an N/A 5.7 with 93 octane fuel generally set at? I understand all the factors involved, I am looking to understand what these numbers actually are...I am logging and seeing WOT numbers of 10-15* at WOT on both MBT and spark advance???

Thanks for the help!!!

[StevoHemi]

This one is over my head. See Jay at Speedy's garage... or Toofart...or AndyPWR... or GSO... or HemiSam.

Stevo

[toofart]

A tuner is likely the only one who can help here... However, one would assume that if you're at WOT, MBT is desired, so the actual spark you're seeing is the MBT target.

In a related note, this document is relatively interesting, and can help understand some of the design considerations in our cars (MAP vs. MAF, injector design with the 'tip')

http://www.sae.org/s...powertrainc.ppt

[lanceschallenger]

A tuner is likely the only one who can help here... However, one would assume that if you're at WOT, MBT is desired, so the actual spark you're seeing is the MBT target.

In a related note, this document is relatively interesting, and can help understand some of the design considerations in our cars (MAP vs. MAF, injector design with the 'tip')

http://www.sae.org/s...powertrainc.ppt

Thanks Toofart. I am just having an issue with my MBT being around 10-11* at WOT and the spark advance around 15-16*. Is the spark advance number the "Total" timing?...Being that MBT is a goal? Why is my spark advance higher?

[HemiSam]

Hey Lance. OK. MBT is Mean Best Torque and is the timing number the ECM would use under "ideal" conditions to generate the most torque available. The correlation is strong between MBT and WOT timing since the car will grab the lowest of the two. Therefore, you want MBT to be the higher number.

As mentioned, if you're gonna be upping timing and playing with fuel I recommend getting a wideband sensor so you can see your AFR's under load. Also, a gauge like an Aeroforce Interceptor will let you see the actual timing and you can plug the wideband output (meaning...get a wideband with an analog output like the Innovate LC-1) and see both AFR and timing on the one gauge at the same time. Don't get a lot better than that

HemiSam

[lanceschallenger]

Hey Lance. OK. MBT is Mean Best Torque and is the timing number the ECM would use under "ideal" conditions to generate the most torque available. The correlation is strong between MBT and WOT timing since the car will grab the lowest of the two. Therefore, you want MBT to be the higher number.

As mentioned, if you're gonna be upping timing and playing with fuel I recommend getting a wideband sensor so you can see your AFR's under load. Also, a gauge like an Aeroforce Interceptor will let you see the actual timing and you can plug the wideband output (meaning...get a wideband with an analog output like the Innovate LC-1) and see both AFR and timing on the one gauge at the same time. Don't get a lot better than that

HemiSam

! There you are Sam! I have the Innovate LM-2 coming...just go confermation that it will ship tomorrow. I have been directed by Diablo to add the same numbers to both MBT and spark advance with the tuner for it to take effect. You have answered my question about where the goal is though...I think! Under WOT, MBT is say 10*...and spark is say 16*...so, I should reduce my spark advance only??? to get it to come closer to MBT???

[HemiSam]

OK. I'm not an expert but I've played around with mine quite a bit. When we talked at the Mile, you were looking for more. With the MS109/higher oct fuel/Torco additive, I say push it. If you're running 93 (and don't even tell me you're running 91 or I'll plug my ears...) then I'd be more conservative.

Here's what I'd do. Load the stocker tune with 93 oct and datalog both the Adv Spk Cyl 1 (I think I got that right...it's the timing in cylinder 1) and the MBT. Hit it WOT through as many gears as you can safely, preferably through 1-4 at least. Do this in cool weather (say morning or night) and then in hot weather with the same tank of 93 oct fuel (good brand like Chevron, Exxon, ConocoPhillips, Shell). Also log your ST KR, LT KR and KR Retard along with your rpm's, Veh Speed and Throttle Position Sensor (so you can tell when you're matting it).

Assuming your ST KR is basically non-existent, then you'll have a good idea of what your base tune's timing is. If you're seeing a bunch of knock, let's talk cause you don't want to be pushing timing if it's unhealthy knock you're seeing. That would be the first order of business. Assuming all is Kosher, I'd then adjust from there keeping an eye on AFR. I don't mind raising timing a bit, but if you want to raise it when leaning it out, then I'd be doing that with the wideband and very cautiously unless you're running the MS109 or some Torco, for example, and then you can get a bit more jiggy

You should see that your timing is dropping as the gears rise. You'll also see it drop right after shifts and then recover. I'm more interested in what it does after timing has recovered (there's a drivetrain protection programmed in the 6-speeds so timing drops below where it was in the prior gear right after a shift so ignore that part...I have a thread going on it on CT if you want more). From there I'd start raising the timing in one degree increments in each of the three rpm bands on both the variables you've listed. You know already you're only doing it at WOT so be sure you're logging at WOT to establish your base.

Under prime conditions I'd expect you'd see 14-15 degrees in the upper gears and a bit more in the lower gears up towards the top of the rpm band. But, they're all different. Different conditions, different fuels and different cars. HAL is a beatch

HemiSam

[lanceschallenger]

OK. I'm not an expert but I've played around with mine quite a bit. When we talked at the Mile, you were looking for more. With the MS109/higher oct fuel/Torco additive, I say push it. If you're running 93 (and don't even tell me you're running 91 or I'll plug my ears...) then I'd be more conservative.

Here's what I'd do. Load the stocker tune with 93 oct and datalog both the Adv Spk Cyl 1 (I think I got that right...it's the timing in cylinder 1) and the MBT. Hit it WOT through as many gears as you can safely, preferably through 1-4 at least. Do this in cool weather (say morning or night) and then in hot weather with the same tank of 93 oct fuel (good brand like Chevron, Exxon, ConocoPhillips, Shell). Also log your ST KR, LT KR and KR Retard along with your rpm's, Veh Speed and Throttle Position Sensor (so you can tell when you're matting it).

Assuming your ST KR is basically non-existent, then you'll have a good idea of what your base tune's timing is. If you're seeing a bunch of knock, let's talk cause you don't want to be pushing timing if it's unhealthy knock you're seeing. That would be the first order of business. Assuming all is Kosher, I'd then adjust from there keeping an eye on AFR. I don't mind raising timing a bit, but if you want to raise it when leaning it out, then I'd be doing that with the wideband and very cautiously unless you're running the MS109 or some Torco, for example, and then you can get a bit more jiggy

You should see that your timing is dropping as the gears rise. You'll also see it drop right after shifts and then recover. I'm more interested in what it does after timing has recovered (there's a drivetrain protection programmed in the 6-speeds so timing drops below where it was in the prior gear right after a shift so ignore that part...I have a thread going on it on CT if you want more). From there I'd start raising the timing in one degree increments in each of the three rpm bands on both the variables you've listed. You know already you're only doing it at WOT so be sure you're logging at WOT to establish your base.

Under prime conditions I'd expect you'd see 14-15 degrees in the upper gears and a bit more in the lower gears up towards the top of the rpm band. But, they're all different. Different conditions, different fuels and different cars. HAL is a beatch

HemiSam

Okay, no knock and I am logging all you have listed. Are you saying that 14-15 degree rough estimate is the MBT # or spark advance #??? Oh...and 93 octane! !

[aarcuda]

im seeing around 3 degrees of ST knk retard right after a shift and then it drops off only to come back after the next shift. im running the 93 CAI tune. i havent tried the straight 93 tune or the 91. what would the other tunes give me? I logged AFR and it was in the 12's throughout the run

[HemiSam]

Okay, no knock and I am logging all you have listed. Are you saying that 14-15 degree rough estimate is the MBT # or spark advance #??? Oh...and 93 octane! !

My understanding is the computer defaults to the lowest of the MBT or the WOT Spark Advance during WOT runs. So if the MBT drops because conditions aren't ideal in HAL's opinion, then that's where the actual timing will be. It's the lower of the two. So if you want to raise timing as an adjustment to your canned tune, raise them both MBT and WOT Spark Advance across the three rpm ranges equally and you should be good. Note...I'm talking about what you're setting the target to. You're talking about what you're seeing in the log...Act Spk Cyl 1. That's what the car is actually doing.

The number quoted is what I expect you'll see in actual spark at cylinder 1.

HemiSam

im seeing around 3 degrees of ST knk retard right after a shift and then it drops off only to come back after the next shift. im running the 93 CAI tune. i havent tried the straight 93 tune or the 91. what would the other tunes give me? I logged AFR and it was in the 12's throughout the run

I suggest you run the 91 Oct CAI tune with 93 octane fuel and see what you get, aar. That was the best for me. The 93 OCT CAI tune was sluggish at best. Log that and give it a seat of the pants butt dyno and see what you think.

When you see you logged AFR, do you mean using an analog input from a wideband like the Innovate or the AFR choice in the Predator. If it's the choice in the Predator, then you're logging Command AFR which isn't the real deal. It should be close on a stock car but I'm not certain. On a blown car or heavily modified car (e.g. ported heads and cam), I think Command AFR and the real AFR could be substantially different.

HemiSam

[Andy@PWR]

Mbt is maximum brake torque

[HemiSam]

Well, I don't think so...
http://www.diablospo...7&highlight=mbt

I've seen the DS tech folks refer to it differently anyway.

HemiSam

[lanceschallenger]

Well, I don't think so...
http://www.diablospo...7&highlight=mbt

I've seen the DS tech folks refer to it differently anyway.

HemiSam

MBT has many definitions out there...they are all based on the same theory. Anyhow, I am not concerned with exact defintion, I am looking for answers to how the 2 numbers corrilate. I believe I am getting closer. It seems that in making best power, that I may not be able to get these numbers to equal each other and MBT is an ideal goal. Getting as close as possible is all I can hope for due to inconsistancys in all variables. I think one of the largest issues I am having comprehinding is that the actual timing under WOT is only around 15*??? Is this due to the VCT cam? Were the earlier non-VCT hemis running these timing numbers? Understanding all the technology and efficiency of the combustion chamber, igniton, injection...etc.... It's just hard to comprehend #'s this low based on all my experience on earlier engines. Basically, the goal is still the same...get as much air and fuel in and out and as much timing as you can run with the fuel your using until it makes the best power..or goes fastest speed (when track tuning)!

Last sentence is in "laymans" terms....point here is I need to quit over complicating this shit! I really don't need to know what the numbers are to make more power and go faster! Get back to basics! Make adjustments until I go just over peak and the back up to peak! N/A there is no threat to the engine with all the safe guards in place. I just want to maximize the potential!

[HemiSam]

Baseline log it like I suggested, Lance. Then you're not guessing. Do it under cooler and then hotter conditions. ALWAYS with good fuel. Then you'll know. I believe what you'll see is higher timing in the lower gears at the top of the band and lower in the higher gears. What exactly it will be is a guess till you log...

HemiSam

[lanceschallenger]

Baseline log it like I suggested, Lance. Then you're not guessing. Do it under cooler and then hotter conditions. ALWAYS with good fuel. Then you'll know. I believe what you'll see is higher timing in the lower gears at the top of the band and lower in the higher gears. What exactly it will be is a guess till you log...

HemiSam

Ya...I have pulled the tune out. I am back to rev limit and speed limit mods only. Gonna log some passes at lunch to see what the factory tune is showing, then go from there.