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Air Box Mod 6mph gains "GPS UPDATE & CORRECTION

Discussion in '4 Stroke Air Intake' started by the kitchen, Feb 25, 2011.


  1. the kitchen

    the kitchen Expert

    Messages:
    214
    Location:
    Readfield, Maine
    I have been reading alot of posts and looked at alot of pics from alot of mods. We all know that colder air will make more hp. In all the testing that I did too much air made no gains at all without adding fuel.

    Some mods open the top of the box and add prefilters, IMO this adds alot of cold air but disrups air flo. Its trying to pull from air from behind, above and below the horns.
    All the air should come from front to back with no disruptions. The changes that I made kept the air going straight back. I put four 1 1/2" bulls eye inserts at the front of the box. I found that this was a little too much air and cut off 1/3 of the air from below. If you look at the pic with the metal screen I had to cut the two outside tabs down as they were directly below the insert.
    For two seasons now my top speed has been 118 on the speedo. Yesterday after my final test I pulled 128 speedo in a shorter distance. This is a huge gain. Below are some pics, hope it works the same for you!

    The only other mods I have are clutch work, timming and plugs.
     

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    Tedonlin150 likes this.
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  3. rxwarrior

    rxwarrior Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    357
    Location:
    Illinois
    Soooooo what clutch work have you done and what product(s) did you use to add fuel? 4 bullseyes and the bottom opened up and then closed back 1/3 of the opening. Am I following you right?
     
  4. Frozenstiff

    Frozenstiff TY 4 Stroke Junkie

    Messages:
    616
    Location:
    Prescott, Ontario
    Country:
    Canada
    Snowmobile:
    2013 Arctic Cat Turbo
    Not trying to be a smart@@@, but I say check your speedo and have it re-calibrated. You ain,t going to gain 10 MPH with that mod alone. Not a chance., but I sure wish it was that easy to gain 10 MPH.
     
  5. the kitchen

    the kitchen Expert

    Messages:
    214
    Location:
    Readfield, Maine
    Rxwarrior, You ask how I played with the air comming in from the pre existing holes that take air from the bottom of the bulk head. If you look at the picture there is a rag in the center hole thus restricting 1/3 of the air flow from beneath. I started with six bulls eyes. Two from which I plugged back up as it was drawing air from behind the horns, (under the head light). This seemed to be too lean and was bogging at low rpms. so I put two rags in the air box with not much gain. I did not add fuel, just stated that the air flo was too high and at that level could only be corrected by adding fuel. As soon as I plugged the back two bulls eys I placed one rag below and went for another run and climbed to 128 speedo. I will replace the rag later.
    As far as clutching goes, it has stayed the same throughout the air box testing. I run the overdrive sheave, cut stock helix, silver spring@ 6-3, two speeds with black spring, I grind the tips and load the shoulder, it holds 10900 throughout.
    #1apexrider, my speedo has not changed. We just got 10" of snow so it will be a bit befor I put gps to a run but when I do I will let you know what it's at.
     
  6. the kitchen

    the kitchen Expert

    Messages:
    214
    Location:
    Readfield, Maine
    Wow are the speedo's off. The gps gains are 6mph. I finaly got to do some testing but the temps are at 33deg. When compairing to speedo when at 121 the gps says 106, when speedo says 130, gps says 112 mph. I beleive that I can get more out of this if I was able to try some runs at 5deg.

    Sorry for the 10mph post I will always get gps readings to post real gains going forward. I knew these speedos were off but this is just stupid when Yamaha knew this in 03 and made no changes on 06.

    Anyways I am happy with the gains. I did not reset moving times but top speed at these temps is 112mph, see photo below.
     

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  7. dmaxx

    dmaxx Expert

    Messages:
    388
    Location:
    sw Michigan
    Country:
    USA
    Snowmobile:
    2012 Apex XTX, 2010 Vector LTX, 2000 AC Z-370..fast
    LOCATION:
    White Pigeon, MI
    Do you need a fuel controller for this mod? How much louder than stock is it?
     
  8. turbo tow-er

    turbo tow-er Extreme

    Messages:
    94
    Location:
    Northbay Ont
    i put a fuel controller this summer on my sled installe the top box ram air kit, and got the exaust modd, gained enough rpms that i now need to add weight to the primary clutch. used to run at 10200 now having a hard time keeping it at 10900.
     
  9. kviper

    kviper VIP Member VIP Member

    Messages:
    2,413
    Location:
    Oakfield WI
    Country:
    USA
    Snowmobile:
    2012 MCX Turbo Apex
    There has to be some other variables going on to come up with 6 MPH gain. If there was enough gain's in air flow to make even 2 MPH gain on top end you will need to add fuel for sure. These sled's do not know air flow to make fuel changes, only barometric pressure and temperature. Any one that has tested these types of mod's in a controlled environment has proven this.
    A good running bone stock Apex can show 130MPH (on pre 2011) on speedo, on perfect condition's, I saw it once on my 06 GT in 100% trail form.
    Sorry but you will never see that kind of gain from air box mod alone.
    I have run air box mod's and fuel controller's on two Apex's now and there are gain's to be made but to gain 6mph on top end takes a LOT of power.
    Actually it is much easier and cheaper to gain top end by chasis set up and track selection than by adding HP.
    It is extremely hard to duplicate condition's run to run on snow. Even bare ice changes drastically during day time temp changes.
    Air flow through the throttle body's is air flow no mater if it comes from top front or what ever. You may get more air flow from one or the other but it requires fuel to go with it to make power and these sled's are not that rich from the factory, unless this sled was for some reason in which case it may have been slower to begin with?
    I am not meaning to wiz in any ones oat meal, just don't want people to expect
    these kinds of gain's from an air box mod alone.
     
  10. FireStone

    FireStone Pro

    Messages:
    138
    Location:
    Quebec-Canada
    you are also talking about timing???
     
  11. turbo tow-er

    turbo tow-er Extreme

    Messages:
    94
    Location:
    Northbay Ont
    if you get a proper fuel controller chip it will advance the timing as you turn its settings up. i have the ram air kit for my apex, with a gutted exhaust. the sound is a killer sounds like a bomb going down the trail, it screams!!! you can easily see a 6 mph gain id never doubt it. a lot of cheap fuel controller chips will do the trick if your modifying on a budget. these work of your air temperature sensor (ATF) and these trick the engine into thinking its colder outside. this feeds the engine more fuel and the stock ecu will advance its timing in accordance. I've had to mix race fuel into my supreme before on a cold day for it not to stall. its real basic work to have more power you need to have more airflow, thus air box and exhaust work. but to compensate for this you'll need to add fuel. find the happy medium increase in power and performance. I've let lots of people drive my N/A sled with these modds and they all say they have never driven such a responsive sled, or that the throttle response is unreal. as for the sound with the open top of the box, you hear a constant sucking noise and a crisp crack when you hammer on it. mind you, i have clutching work done to my sled, a team roller secondary.
     
  12. turbo tow-er

    turbo tow-er Extreme

    Messages:
    94
    Location:
    Northbay Ont
    when modding you have to remember you get what you pay for and nothing should be quick real modds take TIME PATIENCE AND KNOWLEDGE.
     
  13. apex phil

    apex phil Newbie

    Messages:
    5
    bulls eyes

    Where do you get these bulls eyes for air box mods
     
  14. powdermuncher

    powdermuncher Newbie

    Messages:
    13
    Country:
    Canada
    Snowmobile:
    apex
    Just opened my airbox forward below the foam 8 - 1/2 inch holes -- Rpm went up just over 200 rpm same track same clutching same temp air fuel is still in the low 13 to ones with no changes to the fuelmanagment. That is plenty rich for normaly aspirated.
     
  15. wayne m

    wayne m Newbie

    Messages:
    3
    Location:
    PRINCE EDWARD ISLAND
    Country:
    Canada
    Snowmobile:
    2007 YAMAHA APEX GT
    where do i buy the prefilters
     

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