Oversized valves? - Page 2

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  1. #11
    CelicaSupra.com Member
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    Donn29 posted
    "If you do something to the engine to make it suck more air in, the AFM will read it and add more"

    Not quite true. We're talking about wot. The AFM is designed to fully open at 6500 rpm at wot on a stock NA engine. As more airflo capability is added the AFM will fully open at wot at lower rpm. The ecu will probably partially compensate adding some additional fuel since the ecu thinks that the AFM is out of calibration because the AFM opens fully at lower rpm. Tightening the AFM spring and going up to 210 injectors should let the ecu operate closer to normal A/F ratios.
    84 mt 6mge with intake, exhaust, suspension, brake, and wheel mods
    85 mt 6mge stock

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  3. #12
    CelicaSupra.com Member moonpie33's Avatar
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    but with the modified afm and 210 injectors arnt you going to have problems alone the powerband?
    1985 supra 66,000 miles 7mge, to many mods to list
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  4. #13
    CelicaSupra.com Member Donn29's Avatar
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    Quote Originally Posted by StanS View Post
    Donn29 posted
    "If you do something to the engine to make it suck more air in, the AFM will read it and add more"

    Not quite true. We're talking about wot. The AFM is designed to fully open at 6500 rpm at wot on a stock NA engine. As more airflo capability is added the AFM will fully open at wot at lower rpm. The ecu will probably partially compensate adding some additional fuel since the ecu thinks that the AFM is out of calibration because the AFM opens fully at lower rpm. Tightening the AFM spring and going up to 210 injectors should let the ecu operate closer to normal A/F ratios.
    I really shouldn't comment as I haven't really too much AFM knowledge outside of toying with my 5M-GTE. I hope to data-log it once I get the car up and running again to learn a bit more about when it maxes out(which was TPS based I thought, unless the AFM is maxed out, or perhaps the ECU can't tell its maxed out but that wouldn't happen unless you are at wot?).

    However, adjusting the spring tension is probably a better idea than a SAFC, however it is still a bit crude unless you are using a WB or something. My thoughts are this. If the engine is bringing in a touch more air, and the ecu is set to be rich at wot, you'd be getting closer to stoich, thus making more power than adding more fuel may yield. Of course, I'm only talking out of my ass, LOL. Most of my theories are based on Reading between the lines of the TSRM and deciphering what I've read from the forum.
    Current fun car: Black 86 with 7M-GTE/W58/3.58/TrueTrack, 300whp, 13.5@102.
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    "surprise! this one runs 11s biatch"

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  6. #14
    CelicaSupra.com Member moonpie33's Avatar
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    But with too much air and too little fuel wont this lead to detonation even though it is not turbo'd?
    The only reason I said safc is because you can control how much air and fuel the engine recieves!
    1985 supra 66,000 miles 7mge, to many mods to list
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  7. #15
    CelicaSupra.com Member Donn29's Avatar
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    Quote Originally Posted by moonpie33 View Post
    But with too much air and too little fuel wont this lead to detonation even though it is not turbo'd?
    The only reason I said safc is because you can control how much air and fuel the engine recieves!
    I'd be surprised. But Either way I'd use a wideband to determine the amount of lean-ness before adding or making adjustments on a SAFC.
    Current fun car: Black 86 with 7M-GTE/W58/3.58/TrueTrack, 300whp, 13.5@102.
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    "surprise! this one runs 11s biatch"

  8. #16
    CelicaSupra.com Member moonpie33's Avatar
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    good point!!!!!!
    Im gonna build me up a full out head for my 7m like I explained.
    but I'd assume it would be safer to run it on the rich side even with the loss of hp.
    1985 supra 66,000 miles 7mge, to many mods to list
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  9. #17
    CelicaSupra.com Member Donn29's Avatar
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    You'll never know without a wideband if you are just wasting fuel or making the most of those cams and other parts.
    Current fun car: Black 86 with 7M-GTE/W58/3.58/TrueTrack, 300whp, 13.5@102.
    Wifeys Car: Burgundy 84 Auto and stock. Previous Daily: Two Tone Brown 84 Cressida: Sold and helped it get a 7M/W58 Swap
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    Hidden Content Originally Posted by Tire Shredder Hidden Content
    "surprise! this one runs 11s biatch"

  10. #18
    CelicaSupra.com Member moonpie33's Avatar
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    Well I remember seeing/reading that you just cannot throw cams in! Sopposely
    you will feel a difference but you will never achieve all off the power the cams have to offer without further mods. please correct me if im wrong and this also goes for the valves. But i do agree on the wideband. At least you can see what your engine is doing then.
    1985 supra 66,000 miles 7mge, to many mods to list
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  11. #19
    CelicaSupra.com Member Donn29's Avatar
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    Quote Originally Posted by moonpie33 View Post
    ...but you will never achieve all off the power the cams have to offer without further mods....
    I would agree, but by themselves they probably won't hurt anything.
    Current fun car: Black 86 with 7M-GTE/W58/3.58/TrueTrack, 300whp, 13.5@102.
    Wifeys Car: Burgundy 84 Auto and stock. Previous Daily: Two Tone Brown 84 Cressida: Sold and helped it get a 7M/W58 Swap
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    "surprise! this one runs 11s biatch"

  12. #20
    CelicaSupra.com Member moonpie33's Avatar
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    I mean with just valves by themself you would fill a kick in the engine. But I dont see more then a 4 to 8 hp gain I could be wrong on my num just a gestimation.
    1985 supra 66,000 miles 7mge, to many mods to list
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