Dyno'd - Left with questions

[KySilverado]

Hey all,
I left the the dyno this weekend scratching my head. I am not really worried about the numbers I got. Just strange to me looking at the logs I made while on the dyno, why the numbers really weren't any different between the 4 total pulls I made. Maybe someone here with a lot more experinece tuning while on a dyno could shed some light.

All 4 pulls netted within 1HP and 5Tq. Highest being 446rwhp / 451rwtq . Runs made on a Superflow Dyno STP corrected. 90* ambient.

1st 2 pulls done almost immediately after arriving from a 50 mile trip. 1st pull 2nd gear to 6200rpm. Torque converter unlocked. 2nd pull, second gear to 6200 rpm, torque converter locked. Expected to see a difference with locked or unlocked converter? Engine was warm. Blower hot. Logs showed I pulled WOT timing about 5*. Most of run at about 17* total spark advance due to IAT's in the 150* range and timing being pulled by PCM.

2nd 2 pulls done several hours later after truck had cooled off. 1st pull in 2nd to 6200rpm. TC unlocked. 2nd pull done in 3rd gear to 5800 rpm, TC unlocked. Most of run second set of pulls at 22* spark advance due to truck being cooler and IAT's not pulling timing. IAT's around 125* at the end of the pulls.

AFR on all 2nd gear pulls accoring to my wideband and sniffer 11.5 to 11.8. The 3rd gear pull AFR went rich to about 11.0 - 11.2. I have methanol injection on the truck and have yet to get 3rd gear AFR in line with it.

Anyway I think I would see differences in numbers for a +5* timing. Converter locked or unlocked? Hell 25* difference in IAT's should be worth something? What gives?

[WS6FirebirdTA00]

So there was no changed from locked to unlocked? Maybe it wasnt really locked? Remember with meth injection, you want the AFR to be richer becuase the stoich AFR is richer with it.

[KySilverado]

No change from locked to unlocked. I forced the lock with HP scanner. It bucked and such on the dyno spinning up from a stop so I am ASSUMING it was locked.

More confusing to me though, being.... no change with a 5* difference spark advance. Would expect to see something. Good or bad. Same with a 25* difference in IAT's.

[WS6FirebirdTA00]

hmmmm

[KySilverado]

hmmmm

Yeah, kind of what I am thinking. I am gonna take dyno numbers with grain of salt and use actual track times as the gauge for performance.

[WS6FirebirdTA00]

well all that could mean is the higher timing isnt helping you out. Ive seen it happen a lot, esp on a blown car.

[KySilverado]

Thanks that is what I am after. Just need to hear it from someone with experience on a dyno. SOTP tells me it pulls better with more timing, but its been wrong before. Hope to get it to the track this weekend.

[zq8bob]

The timing isn't the whole buritto on this one. The other half of the equation was that your AFR's were 1/2 a point richer or better with the extra timing... which says to me that you might be better off (or at least no worse off) with a little less fuel and less timing. More timing does not ALWAYS equal more power. I've seen a few vehicles where leaner and less timing made more power than rich with more, especially ones with any kind of power adder.

[WS6FirebirdTA00]

True, richer readings normally mean a less effective burn and higher timing could not be burning the fuel effiecntly to make the power it should.

[KySilverado]

I have good comparisons for AFR. First 2 pulls in 2nd were 11.5 to 11.8 @ 17* timing. Afternoon pull after cooldown the 1st of 2 pulls was in second with AFR @ 11.5 to 11.8 @ 22* timing. Same hp/tq numbers. I will not go any leaner than this. Only oddball for AFR was the very last pull of the day. I did not want to do a 3rd gear pull at all but chanced it. Reasons I didn't want to are 1> Knew the AFR would go richer. It probably started out at 10.8 know it ended at 11.2. 2> Driveshafts on these trucks tend to break on the dyno in 3rd. Same hp/torque numbers. Hadn't really thought about it but you guys brought up another hmmmmm.... AFR .5 to 1 point richer and no change in numbers.

I agree with everything you guys are saying and understand the points. Expected to see changes in my numbers due to them. Just didn't.

[WS6FirebirdTA00]

a lot can depend how the meth sprays too. How is it setup to come on?

plus a 3rd gear pull would be more load and difference fueling

[KySilverado]

Its an AlkyControl kit. Triggered by a 2bar map sensor. On at about 4psi boost. It has a progressive ramp from there as I understand it. Total spray volume and ramp adjusted via a pot on a controller in the cab.

Only adjustment I know of for WOT AFR is PE which is based upon RPM. Catch 22 is pulling fuel for 3rd gear rpms makes 2nd gear in same rpm range go lean. Plan on logging MAF frequency, Has to be different airflow/rpm 2nd vs 3rd gear.

[WS6FirebirdTA00]

I know on my buddys car, more boost more spray, so that could be a reason it goes rich on you. Just a suggestion, not saying its the case but thats a big swing in fuel.

[KySilverado]

I agree and think I know why it's gong rich in 3rd. I am flowing less air in 3rd gear vs second at same rpms. I should be adding the same amounts of fuel PE only knows RPM which is same 2nd/3rd, and Meth injection only knows PSI boost which is same 2nd/3rd. Just not certian on how to tune it. Think the only way is with the MAF. Tell the PCM I am flowing less air via the MAF hopefully. 2bar OS might do it but I don't want to go there. I'll take the meth off before I do that.

[WS6FirebirdTA00]

Just curious, why dont you want a 2 bar?

[KySilverado]

Cost, major weather swings here from day to day, season to season. It's my mostly daily driver and I do work with it. I want something that works in all weather.

[WS6FirebirdTA00]

Give us time and we will take care of that issue, but I see where you are comming from.

[EC_Tune]

I think I agree with ZQ8Bob - Too rich & too much spark. See if you can get the AFR up to 12.0 - 12.2.
You can verify increased airflow with the scanner. Dynamic Cylinder air is a very good indicator. 0.01-0.03 increase is good. Make sure that the IAT, coolant, (oil temp if available) are the same before making a run. That will insure absolute repeatability. If you have a quiet straight strech of road......

EC

[KySilverado]

I think I agree with ZQ8Bob - Too rich & too much spark. See if you can get the AFR up to 12.0 - 12.2.
You can verify increased airflow with the scanner. Dynamic Cylinder air is a very good indicator. 0.01-0.03 increase is good. Make sure that the IAT, coolant, (oil temp if available) are the same before making a run. That will insure absolute repeatability. If you have a quiet straight strech of road......

EC

I'm a bit afraid to go above 11.8 AFR with my forced induction setup. Should pick up power if I can at least get AFR out of the 10's in 3rd. I am gonna start logging dynamic airflow to see if there is a difference 2nd to 3rd.

FWIW I picked up .2 and 2mph at the track Friday night with the higher timing and rich. Went 12.73 @ 104.

[WS6FirebirdTA00]

you will have no problem running at a 12.0. I know guys running even more boost than you running 12.0:1. As long as you have good gas and compression for the setup. Only problem is I wonder the role the meth plays into the AFR. On just pump gas, high 11's is good though.