Dyno and 1/4 mile opinions.

Discussion in 'Drag Racing Tech Discussion & Timeslips' started by miltonmegilliii, Apr 13, 2018.

  1. miltonmegilliii

    miltonmegilliii Learning the ways.

    @Dino Dino Bambino this is what i have for you. sorry its not perfect. i have attached a file of the old tuner dyno ( the uppermost line on that graph is actually an old one prior to the sniper install) then the most recent dyno where the guy didnt plot tq so i had to use a calculator and plot it myself. i then did a 500rpm spacing rough comparison graph. the final image was the data log compairing the old tuner and new tuner on throttle input vs throttle acutal. which was one of my areas i was concerned about. and from what i saw i was right. something was off on the old tune.




  2. miltonmegilliii

    miltonmegilliii Learning the ways.

    also i logged at one point the difference in wheel tq error fault. on the old tune the wheel tq error would flat line maxed out as far negitive as the scale went as soon as i was at WOT. the new tune was only about -100 rather than -4000+
  3. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    Your new dyno numbers of 324/326 are better than the previous, with most of the gain at the top end but and a small ~5lbft gain at lower rpm. The A/F ratio is in the ballpark at ~12.4:1, though you could have it leaned out a bit to bring it closer to 13.0.
    I can't help feeling that there's still more potential left in your combination. Did your tuner make the necessary adjustments to the WOT cam timing retard according to the table in the link that I posted earlier?
  4. miltonmegilliii

    miltonmegilliii Learning the ways.

    actually from the rough estimates there is a couple spots down low where the new tune has about a 20ft lb gain and mid range picked up nearly 20hp(3k and 4krpm). it could be in my head but i think i definitely feel the change. i have gone back and forth with my tuner (probably to his distain) picking away how how the logs read and car felt. i trust what this guys is doing so far he really spent time on this one. Also i have a wide band in i believe on the current tune it runs out to 12.8 at wot.
  5. GlassTop09

    GlassTop09 Member

    Good stuff here.
    If I may, I would also suggest the next time you run a datalog to look at your VCT operation to see if it is showing slow response especially down low below 2,500 RPM (too large a gap in time between VCT commanded angle vs VCT actual angle....should be almost on top of each other & in synch when operating properly) as these 3V's oil pressure spec is 75 psi @ 2,000 RPM when all is new so unless you have a mechanical OP gauge installed to know what the actual operational OP is below 2,500 RPM's you'd be making assumptions but by logging the VCT PID's they'll give you some insight into this.
    I say this due to seeing your WOT TQ curve line from 2,000 to 2,500 is almost flat before the TQ curve starts moving upwards looking like the VCT may be a little slow to respond to PCM command until oil pressure comes up some (takes more oil pressure\volume to retard the cams quickly due to overcoming the cam phaser's wound spring tension in addition to the valve spring tension applied to the cam lobes thru the cam followers\lash adjusters & according to Ford they recommend the Hot Rod cams to be around 7* retard for max WOT low end HP\TQ output from 500 RPM's thru 3,000 RPM's....why Dino is suggesting looking at the WOT cam retard timing settings in tune) but the causes as to why VCT response is slowed are many so I suggest to log the VCT PID's (or install a mechanical OP gauge to read actual low RPM OP) to confirm this before chasing this rabbit.

    Been here, done it is why I'm suggesting this & it don't take much oil pressure\volume loss in the VCT system to hurt low end HP\TQ output below 4,000 RPM's on these 3V's.....especially if your engine has high mileage.

    Just a suggestion..................................
  6. miltonmegilliii

    miltonmegilliii Learning the ways.

    @GlassTop09 man that is great info i havnt heard of looking into that before i have tried to do a lot of my own research but havnt seen this yet. ill log it first thing next spring when i get it out of storage. thanks. the engine has nearly 100k on it so i will be looking into it. this may also be a different explanation for my cold start stumble i have been chasing. (cold oil causing issue)
    on cold stat most of the time it stumbles when i apply the throttle below 2krpm. once its warm there is no issue. i was thinking maybe it was slow responding and old O2 but ill check out the vct. much apprecitated.
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