Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 28
  1. #1

    Pushing WOT AFR's

    I'm wondering how far I can safely push WOT afr's and where the problems lay.

    My understanding, please correct me if I'm wrong, is that running too lean under heavy load causes excess heat which can warp the head, melt the pistons. Also, the excess heat causes pre ignition of the fuel before the correct ignition point, if the octane is too low. (Knock).

    So given I am managing my fueling very carefully, logging and autotuning my afr's with infinate accuracy, how far could I push my WOT afr? I am running a 158 stat and currently running pump super octane (98 RON european).

    Not sure if the v-tech tune on the stock ECU retains the knock sensor and subsequent pulling of the timing?

    Today I pull 11.7-11.9 at WOT.

    My aim is to squeeze out a bit more from the block without taking too high of a risk.

    Thoughts??


  2. #2
    Mothman's Avatar
    Join Date
    May 2011
    Location
    West Texas
    Posts
    2,996
    +1
    1,477
    Your afr looks good, and pretty safe.
    Unless you plan on running a higher octane fuel capable of resisting detonation, you probably shouldn't lean it out. If you run a higher octane fuel, then you'll need to bump timing too.

  3. #3
    AtoMIC_OraNGE greenbullet's Avatar
    Join Date
    Jul 2010
    Location
    Barrie / BuckHORN Ontario
    Posts
    2,509
    +1
    234
    Afrs are fine where they are I'm running stock Pistons still until a leak down or comp test tell otherwise And my Afr has always been tuned to 11.9 wot at 8600. 11.7 at 8700-8800

  4. #4
    imp0ster's Avatar
    Join Date
    Dec 2011
    Location
    Palm Harbor, FL
    Posts
    5,037
    +1
    672
    it's common for people who use X-SC and 42s on a 215 to be well beyond 13 WOT. I was measuring 14.5 numerous times. When I first dialed in the 137x4 I was about 12.9 @ 9700 but I was running VP 110. These engines are extremely durable and as long as you're not running shit gas you can safely run low 12s with a 137 wheel assuming your tune is right.

    If you're running the stock X 11.9 is rich IMO

  5. +1 by:


  6. #5
    boost junkie skidoochris's Avatar
    Join Date
    Mar 2012
    Location
    Davison, Mi
    Posts
    4,494
    +1
    476
    if your in the 12s you have no safety net with pump fuel
    so if you get old low octane fuel you are more likely to damage your motor
    when running the higher afrs

  7. #6
    Quote Originally Posted by skidoochris View Post
    if your in the 12s you have no safety net with pump fuel
    so if you get old low octane fuel you are more likely to damage your motor
    when running the higher afrs
    Actually that's a good point. Especially with some of the middle of nowhere pumps you find on our waters! Due to the seasonality of the waters here, there's a good chance of crap fuel at the beginning of the new season.

  8. #7
    Mothman's Avatar
    Join Date
    May 2011
    Location
    West Texas
    Posts
    2,996
    +1
    1,477
    I haven't bought fuel on the water since 99 while running an old smoking ultra 150.
    Pick a trustworthy fuel station, put 5 gallons or more in your vehicle, then fill bunch of 5 gal fuel cans to take to the lake. That way you know the pump is producing 91oct or 93oct and you aren't receiving the gallon or so of 87oct left in the hose in your first can.
    I use the same station, or a handful of trustworthy ones between here and there, and never had an issue while running pump fuel.
    I did find that 12.3-12.5 made it extra snappy a few years back while running the stock 8.4's with an xxx. I dialed it back to 11.9ish to be safe.
    Run what you feel to be relatively safe. 'Safe' vs 'crisp and snappy' is a slippery slope.

  9. #8
    Bob 1tommygunner1927's Avatar
    Join Date
    Apr 2007
    Location
    Houston, Texas
    Posts
    6,344
    +1
    965
    If you're using pump gas you are using E-10 gasoline. Stoich for pure gas is 14.7, E-10 is 14.13.

  10. #9
    Mothman's Avatar
    Join Date
    May 2011
    Location
    West Texas
    Posts
    2,996
    +1
    1,477
    Take time to search for stations still selling non-ethanol fuel. They are difficult to find, but worth it. It'll yield more power and maintain a longer shelf life if you store your ride over winter.
    I run 100LL now, so no ethanol for me. That stuff is evil.

  11. #10
    imp0ster's Avatar
    Join Date
    Dec 2011
    Location
    Palm Harbor, FL
    Posts
    5,037
    +1
    672
    100LL all the way. Smells good too

Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. AFR's rich at idle, lean at WOT. Help!
    By d rabbit in forum 4-Tec Performance
    Replies: 18
    Last Post: 08-18-2014, 08:21 PM
  2. Replies: 48
    Last Post: 07-27-2013, 11:00 PM
  3. AFR Gauge reads 22.4 at wot.
    By ultramaxracing05 in forum 4-Tec Performance
    Replies: 33
    Last Post: 06-11-2011, 08:48 PM
  4. afr at wot????
    By MR MAC in forum Yamaha PWC Performance (4-stroke)
    Replies: 1
    Last Post: 05-29-2010, 07:01 PM
  5. What is the correct AFR @ WOT ?
    By mrbtd in forum 4-Tec Performance
    Replies: 3
    Last Post: 05-24-2009, 04:52 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •