I've been working on this tune after some major mods and I just feel like I'm missing something. The low end power is great but the mid range is lacking and the transmission shifting is out of whack. do I need to do an Allison relearn? Also not sure about the torque management and burst knock. My injector duty cycle seems high as well. any help would be appreciated.
Last edited by 1970ss8.1; 05-03-2019 at 01:30 PM.
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1970 Chevelle SS 8.1 Vortec T56 9" 3.00
2006 3500HD 8.1 vortec Allison 6sp 4.10 4X4
2013 Audi A5 Cab 2.0tfsi Quatro
www.mcmnapa.com
What mods have you done? From the looks of the datalog it seems like you have maxed out your fuel system. It starts to knock where the injector duty cycle is 90+%. I like to keep my cars under 80% duty cycle.
Cam, roller rockers, heavily modified intake, 90mm throttle body, k&n cai, ram air hood, high flow exhaust.
What kind of fuel are you running?
91 Chevron
to me it looks good.
smooth tables, blended maf transition is pretty clean, pe is done the right way, got the wideband reading within a few percent.
showing a tid bit of knock on the top in my scanner, but easy to clean up if you wish to chase it down.
i show max duty cycle of 93% by 4800 rpm... those injectors are done flowing fuel. time for upgrade.
Last edited by cobaltssoverbooster; 05-07-2019 at 12:38 AM.
2000 Ford Mustang - Top Sportsman
My cam stops making power at 4500. Also my trans shift point is 4500 and redline is 5000. If I?m hitting the end of my RPM and maxing my duty cycle at that point should I still upgrade. I have a set of 42lb marine injectors waiting to go into my chevelle, should I put them in this motor. If this motor runs out of injector then the 42?s might not be large enough for the chevelle.
I personally would still upgrade. From the courses i have taken and books i have read they always recommended to keep the duty cycle under 80%. I would not be able to say if they are big enough for the chevelle because i do not know what you are running in the chevelle.Originally Posted by 1970ss8.1
The chevelle has same motor, but 505 cubes, extensively ported heads with smaller stem valves with 5 angle valve job, large cam that runs to 6500rpm, roller rockers, comp springs, heavily ported and modified intake, 102mm throttle body, long tube headers, dual 3? exhaust, and backed by a T56. It is basically a pumped up version of GMs HP3 engine. The HP3 ran 42lb injectors, but my intake flows way more than the HP3 and I have more cubes. The HP3 ran the stock intake with 78mm throttle body.
Last edited by 1970ss8.1; 05-07-2019 at 03:05 PM.
I try to keep my injectors between 85-90% duty cycle for longevity reasons that i am not good at explaining. Also flow in some injector sets doesnt give much change in that really high duty cycle range. So if corrections had to be made latter down the road, as an increase in airflow, then your injectors may not have functional room.
2000 Ford Mustang - Top Sportsman
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