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Turbo build and some ideas on part spark/fuel

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Old 01-30-2018, 01:43 PM
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Default Turbo build and some ideas on part spark/fuel

SO on my turbo LS1 auto I finally have a decent base tune and going to take it to a formal dyno tune BUT I am still having fun trying to get idle/part throttle going.

Cam,Stall, Turbo,Auto, Injectors

IU am SD Mafless and used the Hptuner guides, and it idles fine at 800rpm.
The Injector data seems to be working great and I played with EOIT.
I also adjusted PE to come in sooner since it seemed I was having spark knock at part throttle 2800-3200 20-32g range always always 0.2-1.0 pull if I hit the pedal to hard.


Then I dialed down burst knock from 0.0.15 to 0.8 and it went away and the with some EOIT tweaks it ran much better.

Now I can cruise/idle perfect and hiways stabs are great above 3600.
Part throttle now works but I dialed back the stock timing though to get it and it seems soft,weak to grow RPM/Speed at part throttle now.

My Hi Octane table I pulled a lot of timing. from 1600-3600RPM and from 20grams to 40grams I dropped 6 degrees and fade out to -2 at 3600.

So where it was 34deg off idle stock, then down to 28 it is more like 30 down to 26. This is all Non Boost 50-80KPA.

Is it normal to have to pull timing with stage 2 cam and turbo? Even with no burst knock I tried adding back the stock timing and I did get some knock and hesitation and I backed off. It doesnt like tip in spark.

My spark curve at 0-10% throttle will go up to 31-34deg then I lay into 20% throttle it now dips to a flat curve from 25deg. If I lay into it it will then dip to 12.5 in boost or if I lay off and cruise it will go up to 34deg again.

It seems off. Stock it looks like it stays around 30deg part throttle.

Fuel seems too rich probably. Both NB register 0.850-0.950 most of teh time under load and and WOT. It idle one NB sits rich and the other fluctuates which averages out to around 470MV.

I can post my tune file later tonight.
Old 01-30-2018, 03:43 PM
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in racing, it is useful to time based on how full the cylinder is, and the rate of change of rpm. if the rate of change is increasing fast it is safer to use more timing with full cylinders. If the rate is not changing as with steady state dyno, or even decreasing, as with brake boosting, the timing will not be as advanced there because an advanced number could lead to severe pressure spike which would put a hole in something, hopefully the head gasket. Each gear has its own rate of change, there are timing vs gear maps, however we generally time an engine for 1:1 final racing gear rate of change.

This is all negligible in street applications because we want to use an even lower number for safety. So find your minimum timing with the dyno in a hot terrible condition and use it, only adding slightly for colder weather.
Old 01-30-2018, 05:37 PM
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I find most stock tunes have way too much timing and way too little fuel.

i know you didnt speak to fueling, but what are your AFR's like?

what is your pe/be enrichment set to? how about PE enable %?

most stuff I look at PE doesnt kick in until like 80% throttle...yikes.
Old 01-31-2018, 08:23 AM
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Post the tune or some pics of the timing and fueling tables.



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