Running it rich
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Thread: Running it rich

  1. #1
    1000+ Posts Luca's Avatar
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    Default Running it rich

    Guys I know the dangers of running an engine too lean.

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    BUT

    Are there any dangers of running a motor too rich??

  2. #2
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by Luca
    Guys I know the dangers of running an engine too lean.

    BUT

    Are there any dangers of running a motor too rich??
    Escessive carbon build up and more importantly you'll wash down the bores.

    '92 205 Mi16
    '90 Mi16x4

  3. #3
    1000+ Posts Luca's Avatar
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    Pete does it affect the performance in any way?

  4. #4
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by Luca
    Pete does it affect the performance in any way?
    Yes. There's quite a big difference in performance between 11:1 and 12.7:1 air fuel ratio.

    '92 205 Mi16
    '90 Mi16x4

  5. #5
    Fellow Frogger! MYT205's Avatar
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    In theory that is true but not always the case.

    Some cars will make more power at different AFR's.

  6. #6
    Fellow Frogger! 20FIVE's Avatar
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    Apparently they may also cause problems with your piston rings disintegrating.

  7. #7
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by MYT205
    In theory that is true but not always the case.

    Some cars will make more power at different AFR's.
    Darren's sort of right. Most street cars will make most power in the range 12.5-13:1. You could run an injected car at 13:1, but the same engine on carbs might need 12.5:1. It's all got to do with volumetric efficency. As the VE goes up, so does the ideal AFR. V8 Supercars run in the high 13's, low14's. But they probably have a VE of something like 110%.

    Some manufacturers run rich mixtures as a safety measure. Turbo Commodores and WRX's for example, run 11:1 at full boost. This helps keeps things nice and cool but doesn't make the most power. Adding an adj. ECU and leaning up the mixture increases power dramatically. But the safety margin also dissappears. One detonation and it's all over.
    Last edited by PeterT; 28th June 2004 at 05:23 PM.

    '92 205 Mi16
    '90 Mi16x4

  8. #8
    1000+ Posts Warwick's Avatar
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    Darling, it will give you better response, but less power at revs.
    What is your thinking with the rich thing?

  9. #9
    1000+ Posts Luca's Avatar
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    Well.....

    I'm getting it dynoed (finally) and have booked it in and all..... now they guy is gonna tell me it's rich here and it's lean here blah blah blah.....

    I'm thinking it's better to have it run rich than lean and hence my next Q....

    What can I do to adjust the mixture? I know that the fuel reg i've got is adjustable (currently running on 3.5 bar at full vacum and 3 bar on idle) but my mind has been doing overtime at the other options i've got on adjustign the mix.

    from memory there's something under the black cover on the AFM??!!?? NO?

    and pls don't tell me to get a fully mappable ECU.. thoughts?

  10. #10
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by Luca
    Well.....

    I'm getting it dynoed (finally) and have booked it in and all..... now they guy is gonna tell me it's rich here and it's lean here blah blah blah.....

    I'm thinking it's better to have it run rich than lean and hence my next Q....

    What can I do to adjust the mixture? I know that the fuel reg i've got is adjustable (currently running on 3.5 bar at full vacum and 3 bar on idle) but my mind has been doing overtime at the other options i've got on adjustign the mix.

    from memory there's something under the black cover on the AFM??!!?? NO?

    and pls don't tell me to get a fully mappable ECU.. thoughts?
    For $50 exchange, I'll modify your ECU so it gives better throttle response and unlimited RPM. This mod, together with your adj. regulator, is all you'll need on your 205. I've found that 3.5 Bar is too rich with the std. injectors.

    '92 205 Mi16
    '90 Mi16x4

  11. #11
    1000+ Posts Luca's Avatar
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    Peter what will this mod do to improve my dilemma of not being able to adjust the mix?

    And is 3.2 bar better?

  12. #12
    1000+ Posts dino's Avatar
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    I've found that 3.5 Bar is too rich with the std. injectors.


    Totally agree......but wouldnt bigger throtle luca has partially compensate???
    Luca....R your plugs fouling?.....might be wise to look at some hotter plugs.....I had a similar rich mix problem on my 205 (I think most gtis suffer from this) and the 4 pronged bosch super4s fouled up pretty quickly......
    Re AFM.....I had my reset so that the flap opens up a little easier (loosen the tension)....I did the job myself.....but i would only recommend a very "slight" reset.....then turn the AFM so gravity helps flap.....it works really well on my GTi....Idles smooth as silk (how rare is this on a gti???)and response is smooth throughout the rev range......Would a more potent COIL help compensate with burn?
    Obviously though...I still preffer it slightly rich.....who needs holes in their pistons....plugs are way much cheaper to change....


    cheers

    dino

  13. #13
    1000+ Posts Luca's Avatar
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    I've got the Platinum NGK issue plugs that went in with the recent rebuild and they're up to the job.... the AFM is brand new and I guess I'm looking for options other than changing the ECU when it comes time for Mr. Dyno Man to get my little car howling...

  14. #14
    1000+ Posts dino's Avatar
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    Platinums...?...in the 205????....Wow thats ....ummmm...interesting...
    Vey EXPENSIVE.....very reliable.....but R THEY FOULING.....????
    I d go out and spend the lousy $12 on some champion GOLDS...bring them with you on the day you do the dyno (they need a few kays to run in though ie burn off)....and try and do a run with them....bet you get an extra 1HP and car will idle smoother....
    Good luck with the dyno....I m looking forwards to seeing the results considering the style of mods on your car....It would be interesting to see what the dyno man can actually do on a GTi to give it the few extra horsies....I suspect FA as you probably know your car better than he might.....

    cheers


    dino

  15. #15
    SMP addict pugjet's Avatar
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    err...dino, whats interesting re: platinum plugs on a 205 gti?

    is there something i should be concerned about?

    reason being, ive gone one notch above the platinums and fitted ngk iridiums.


    sorry to highjack yer thread, luca.
    current frogs :
    '94 s3 alpine 205GTi

    daily ding magnet: '98 1.8 16v citroen xsara


    previous frogs:

    88 S1 205GTi
    '95 306S16


    gimme corners. . .


  16. #16
    1000+ Posts dino's Avatar
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    err...dino, whats interesting re: platinum plugs on a 205 gti?


    ....welll...its just that the "platinum" option is usally taken up because of lthe much longer servicing intervals required......ie....platinums are supposed to be good for 50-100K...thats a lot of kays.....So if you ve got to take half an engine out to get to the plugs....platinums are obviously a good option ie.V6 camry and many others...

    Now on the other hand....the plugs in the 205GTi are quite easy to access and replace...what...all of 10 minutes even for a novice....This was my point.....
    Fine,...Luca has a REBUILT engine and when a car is running well the platinums will last a long time.....BUT no matter what anybody tells you....the platinum plugs(hell i think this applies to iridums 2)are NOT a performance plug...Infact they usually perfom below par compared to many other standard plugs....

    I was a little bit confused that the car is running platinums (which were put in during rebuild) since Luca is talking about a rich mixture.....I suspect his platinums "might" be in a more sorry state now.....and if he was going to DYNO the car...it might be wise to DO it with a fresh set of plugs.....
    But otherwise no there is nothing wrong with platinums or iridiums for that matter...but at $20-$25 EACH...I dont think they R worth it in this environment.....but then again...I like to put fresh plugs in regularly....In the 20 K i ve done with my GTi...I ve changed them at least 3 times, maybe 4.....but hell....I was never paying retail...


    CHEERS

    dino
    Last edited by dino; 30th June 2004 at 12:07 PM. Reason: lousy spelling...I stand corrected...appologies to LUCA

  17. #17
    1000+ Posts Luca's Avatar
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    Dina... i mean dino... firstly u spell my name Luca and secondly a plug creates a spark dude there's nothing performance related about an item that creates a spark. The material in which they are made pertains to longevity.

  18. #18
    Fellow Frogger! MYT205's Avatar
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    Quote Originally Posted by Luca
    Dina... i mean dino... firstly u spell my name Luca and secondly a plug creates a spark dude there's nothing performance related about an item that creates a spark. The material in which they are made pertains to longevity.
    I hate to tell you this Luca but there sure is.

    You can pick up significant amounts of hp by getting a better burn which is all brought about by the spark. Plugs CAN make a difference but mainly more hp is gained from better ignition systems involving better coils and MSD type units.

  19. #19
    1000+ Posts Luca's Avatar
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    Dude a spark is a spark... the gains are from spark position (Afla twin spark)and spark timing (fully mappable ECU).

    But that's straying away from what I wanna know and moving towards changing the ECU to something fully programmable.

  20. #20
    1000+ Posts dino's Avatar
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    Luca......the point I m trying to make is that I would RATHER change My plugs more often if the car is running rich...(cleaning plugs -mechanically-is a big NO NO....since the sharp edges are what gives a good spark)
    ie....cost of a typical PLATINUM is about $23 EACH whereas the cost of a standard or better like the champion GOLD is app $3 -$4 depending wether its resistor based or not......So we are talking about a 5-6:1 price ratio....meaning I can change my plugs 5 to 6 times for the price of your platinums....making sure car is being run more often on FRESHER plugs.....
    Its your choice obviously but having a fresh set for dyno day will give YOU a less
    QUESTINABLE dyno result....
    So I m not being argumentative......comparing new plugs against one another (1 brand versus another)...no there wont be much difference....BUT comparing...POSSIBLY fouled plugs against ANY new set can reveal 1-5HP depending on factory output, capacity (na/blown) and condition of fouled plugs....One thing is SURE....Platinums are one of the worst perfomers when fouled as, like u said they r designed for longevity not spark power....


    cheers


    dina

  21. #21
    1000+ Posts dino's Avatar
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    ...might be time to invest in a stoich. guage.....VDO make a nice unit...there is autometer.......etc.....


    cheers

    dino

  22. #22
    1000+ Posts Warwick's Avatar
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    No need to modify an ECU Luca.
    Why would you; If you are running the right amount of fuel through this regulator and have the spark doing the right thing it should respond fine. Yours obviously isn't set-up right.
    You're not running the straight through air filter are ya? I would straighten the bastard. But this won't make any difference though.

    Depends on how the head flows and stuff I guess, but mine was backed off to 3.2 bar from 3.4 (which was from a manual set-up). In doing this and other spark stuff I got 10 bhp more out of the dyno session.
    I was using some sorta other (new) plugs, and after whacking in Platinum NGK's the car was transformed.

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