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Thread: Injector End Angle Tuning

  1. #71
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    You're welcome, and thanks for the compliment.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  2. #72

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    This thread is very interesting. I just finished reading it last night and was playing around with one of the spreadsheets attached to a post 2-3 pages back. Since idle is the place where injector timing is likely to show a difference, I thought it would be fun to warm the engine up, then change the injector end point from the angle as calculated by the Holley software (5.130) up to overlap to see what effects might be noticeable. Quite interesting, I'm just going to post this picture here. IEA starts at -74°, then I added 20° at a time up to -194° where a really obvious effect of overlap showed up. Caveats are I had to allow CL Comp to exceed -10% about halfway through the 2nd step (-114°) and IAC zeroed out eventually causing some wider swings in CL Comp.

    Click image for larger version. 

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  3. #73

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    Got an email from someone who worked on this. Quite math heavy, but interesting no doubt. The output is similar to what I come up with, but without so many steps. He also takes velocity into consideration at the low end: https://drive.google.com/open?id=0B0...s4UGt4Z2hxbmlj

  4. #74

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    Interesting! I started with that same spreadsheet and added a port velocity calculation per RPM, but I did it via adding inputs for bore, stroke & port area & calculating the velocity in the background, the delay adder to pulse width being based on said velocity and injector distance from the valve. I don't believe the fuel velocity effect is predictable. I see they used a weighting factor to try to deal with that. Seems many injectors don't even point at the intake valve anyway, so I decided to ignore the fuel velocity effect. The difference in delay from the one you link to compared to mine is I calculate about 30% more delay down low, and about half the delay at peak RPM. Seems like a lot, but it's not all that significant in reality, at least if one's injectors are sized properly.

    Before this I had numbers ranging from -74° to >+68° as calculated by V5 for Injector Phasing. Car runs great so this is tweaking for efficiency. So using my experiment as a guide, I decided that -140° was a good safe place at idle. My spreadsheet predicted -125°, but the testing showed that it started to hit peak efficiency right around -134° right through -154°. So I took the -66° I added at idle and just offset the entire table. Any cells that were still positive in the upper right I zeroed out. Done. Haven't had a chance to try it, but I'll be surprised if I notice much other than needing less air at idle. Oh, and I changed the most left column to 150 RPM so I have some control over cranking PW fuel timing. I noticed some had done this, seemed like a good idea.
    Last edited by Cougar5.0; 10-04-2019 at 08:17 AM. Reason: Fixed confusing wording about cranking PW

  5. #75

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    Quote Originally Posted by Cougar5.0 View Post
    Seems many injectors don't even point at the intake valve anyway, so I decided to ignore the fuel velocity effect.
    I talked to an engineer who has experience with some high end setups and was willing to share information. He stated for maximum power production the spreadsheet will never work. Even changing the angle - not distance - of the injector relative to the airstream will have an impact on maximum power and will change where it will want the IEA to be.

    There's a lot more going into all of this than we can math. Obviously the high end stuff like Pro Stock is all WOT all the time and they'll be tuned on a dyno anyways, but for us mere mortals who just want a smooth engine and couldn't give a rat about 3 HP up top, the spreadsheet numbers seems to work great.

  6. #76

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    I can vouch for that last sentence! I'm just trying to optimize driveability & maybe save an ounce or two of fuel in the process. The driveability is pretty subjective, but I didn't feel any double-clunks with my 1500 RPM 5th gear tip-ins compared to before optimizing IEA. I believe the oscillations at tip-in are smaller too.

    Since it's easy to do an A/B comparison at idle, here are the stats whilst changing IEA from -74° to -140°. These are average numbers at idle before & after:
    Before: 916 RPM, 2.99 msec Inj PW, -3% CL Comp, -7.72 inHg vacuum, 7.8 lb/hr Fuel Flow.
    After: 897 RPM, 2.67 msec Inj PW, -12% CL Comp, -8.28 inHg vacuum, 6.7 lb/hr Fuel Flow.
    The numbers show why this was a worthwhile exercise. Probably could get 10-15% better mileage now (if I ever drove it like a normal car, LOL). I also get a little more vacuum for my brakes (at a slightly lower RPM), always a good thing.
    Last edited by Cougar5.0; 11-11-2019 at 11:37 AM.

  7. #77

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    Quote Originally Posted by allan5oh View Post
    I talked to an engineer who has experience with some high end setups and was willing to share information. He stated for maximum power production the spreadsheet will never work. Even changing the angle - not distance - of the injector relative to the airstream will have an impact on maximum power and will change where it will want the IEA to be.

    There's a lot more going into all of this than we can math. Obviously the high end stuff like Pro Stock is all WOT all the time and they'll be tuned on a dyno anyways, but for us mere mortals who just want a smooth engine and couldn't give a rat about 3 HP up top, the spreadsheet numbers seems to work great.
    Hi Allan. I sent you a message on your spreadsheet/program calculator. Mark

  8. #78

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    Hi Allen. Here's what I came up with in your calculator. Do I just zero out the table after 2000 RPM? The S2H method would give me -12 to -16 in the idle area, any comments? I have a 605 Gen2 Hemi. Thank you, Mark.

  9. #79

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    Are you the guy that left a couple messages on my voicemail? I've tried to call back without success. Generally you want around -150° in the idle area. I'm kind of concerned with those positive numbers. I haven't played with the spreadsheet a ton; it isn't mine, but that doesn't seem right. I'll call you again tomorrow. I'm in the middle of a Series 60 In-Frame.

  10. #80

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    Yes, it was me that called you. I left you my phone number in-sourcing Private Message. I talked with Rich Nedbal, and he told me positive numbers are very bad...talk later!

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