[mikeo]

For your entertainment I offer a recent 3rd gear pull of my HMR turbo on a Mustang dyno. This was the last run of a tuning session. Injectors are 83 lb/hr. EMS is a TECgt using manifold absolute pressure to determine inlet air flow. Driveability is good but it does backfire a little when I let off after strong acceleration.



   



Peak power/tq is 358 rwhp/337 ft-lb. Let the analyses begin <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />

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[xrad]

NICE! is this with the Mahle pistons in Alusil 104.5mm bore or did you get liners?

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[mikeo]

Alusil 104.5 bores with HMR spec Mahle pistons.

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[SpeedForceRacing]

Looks pretty good.You might have been able to smooth out the mixtures a little if you made a few more passes. The backfiring coming off the throttle can be adjusted in your decel enrichments in the TEC software.

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[flash]

looking at the afr curves, it is clear that you are rich all over, and really rich up top - i would look into leaning that out a LOT and perhaps dropping boost a touch - you may not get the peak numbers, but that's not what really matters anyway

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[SpeedForceRacing]

Flash,



I would disagree with you on one point and that would be the target AFRs.Lows 12's to high 11's are perfect for forced induction cars.It leaves a bit of a safety net, will not be detremental to power and prevents you from being on the ragged edge like you would if you were aiming for high 12 AFR's like 12.5-12.8 to 1.

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[flash]

and i would prefer for it to be "right" - i would prefer a better mixture with less boost than run rich and do the damage that is incurred from that - been there done that - an all too common thing with many tuners - sure, it makes a bit more power in the shop, and some richness can even help cooling, but too much is bad - also, it just doesn't run that way for long - better to use a bit less boost and get a good mixture - no need to ever go below 12 - the problem with that curve is how much of it is rich - there are areas where it looks ok, but most of the curve is too rich

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[xrad]

agree w/ speedforce. The damage from running a little rich will occur over the long haul and you can smooth the programming to get a good balance. The damage from running lean can occur over a few hundred rpms and would really suck.



Most every tuner will tell you start rich and work towards a good slightly rich near stoich balance. One nice feature of the Haltech unit is the ability to manually smooth out large ranges of a/f mixture points making this adjustment easier. Additionally, there is wideband O2 feedback loop option. Don't know about TEC units.



Another point is to make sure you have excellent boost controller and/or have a set boost spring rate at a safe level.



Another good point is that to tune correctly, you need exhaust gas temp taken between head and turbo AND from the same crossoverpipe, an exhaust pressure reading. Compare the intake pressure to the exhaust pressure.





I think 83lb hr inj's are right for this engine, allowing laterality without reaching peak opening times.



1 bar set or 1 bar reached?

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[flash]

i also agree that lean is worse - i further agree that you start rich and work down from there - he has done that though, and i think it's time to lean it out in the rich areas until he nails the mix as flat across the curve as possible

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[xrad]

yep...what kind of feedback O2 loop on TEC unit, Mikeo? How quick does it sense and adjust..cycles per sec??



EGT?

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[mikeo]

[quote name='xrad' post='66437' date='Feb 2 2009, 08:40 PM']yep...what kind of feedback O2 loop on TEC unit, Mikeo? How quick does it sense and adjust..cycles per sec??



EGT?[/quote]



I run the engine open loop so the measured AFR does not influence fuel injector on time. Some think this is crazy and I accept their right to feel that way. I follow the school that says a sensor failure is more likely and it is better to rely on good tuning and a reliable EMS like theTEC.



Too rich? Maybe a little but I'm with Tim on this. I have to fiddle with the boost controller and the fuel/ignition maps some more.

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[flash]

lol - no worries - i remember the old days when we didn't have those fancy schmancy electronic gizhachies - we had to nail it by getting it right from the get-go with the right size jets, springs and weights

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[xrad]

Mikeo: yes, good to tune on open loop, and maybe race to when rpms are in a fairly constant range and altitude, B press, etc are fairly constant. For real street driving, I think that closed loop allows more fine tuning to make up for day to day variables. Whatever works......



of course when tuning, I hope you are hooked up at the minimum to an O2 sensor and exhaust temp sensor... ......

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[flash]

we used to tune on a closed loop, but then construction started and the cops started nailing us

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[xrad]

Flash: how did you tune on a closed loop? I have tried this, But the constant cycling of the O2 feedback always messed with small as well as large incremental tuning changes..... I was fighting the O2 feedback loop which made the process much harder

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[mikeo]

[quote name='xrad' post='66517' date='Feb 3 2009, 07:57 PM']Mikeo: yes, good to tune on open loop, and maybe race to when rpms are in a fairly constant range and altitude, B press, etc are fairly constant. For real street driving, I think that closed loop allows more fine tuning to make up for day to day variables. Whatever works......



of course when tuning, I hope you are hooked up at the minimum to an O2 sensor and exhaust temp sensor... ......[/quote]



Two egt channels in the cockpit and the AFR is on the plot above <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" />



For street driving, the TEC is measuring the thermodynamic properties of the intake air and is controlling timing and fuel based on the mapping we established during driveability and power tuning. So I don't really understand how street driving will be more challenging for the TEC than on track driving. Help me to understand that.

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[flash]

xrad - take two steps back from the screen - now squint real hard at the type - now lift one foot off the ground



feel funny?



no?



repeat process while patting self on head and rubbing belly



funny yet?

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[xrad]

race track? v. Closed O2 loop....makes more sense... Thank God, I thought our leader was losing it.... <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[flash]

actually it was a group of roads in a commercial area that had not yet been developed, but we did call it our own private little racetrack

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[SpeedForceRacing]

[quote name='xrad' post='66437' date='Feb 2 2009, 07:40 PM']yep...what kind of feedback O2 loop on TEC unit, Mikeo? How quick does it sense and adjust..cycles per sec??



EGT?[/quote]





You can adjust the amount of feedback, authority range and samples per second. It can get a little tricky to get it right and have a car that does not lope around idle.





[quote name='mikeo' post='66512' date='Feb 3 2009, 06:47 PM']I run the engine open loop so the measured AFR does not influence fuel injector on time. Some think this is crazy and I accept their right to feel that way. I follow the school that says a sensor failure is more likely and it is better to rely on good tuning and a reliable EMS like theTEC.



Too rich? Maybe a little but I'm with Tim on this. I have to fiddle with the boost controller and the fuel/ignition maps some more.[/quote]





I think you did pretty good. Just a few minor tweaks and you should have it nailed down. Did you use the 3D graphing? It helps to smooth out peaks and valleys.

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