aceltx09
Expert
All this talk about the airbox I'm just not convinced. Especially when I hear you don't need to add fuel. Engines from the factory are designed to run perfect combustion 14.7kg:1kg, air:fuel so if you increase air but do not adjust fuel not sure how you are gonna gain anything, other than run the engine to lean. I'm sure with a fuel commander there can absolutley be gains, but just adding more air does not seem right
- Joined
- Apr 17, 2003
- Messages
- 5,347
- Location
- Menno, SD
- Website
- www.ulmerracing.com
- Country
- USA
- Snowmobile
- 2014 Yamaha SR Viper LTX, 2014 Yamaha SR Viper RTX SE, 2015 Yamaha SR Viper MTX SE 162 (turbo), 2015 Yamaha SR Viper MTX SE 153
- LOCATION
- Menno, SD
- WEBSITE
- www.ulmerracing.com
The stock setup does not run anywhere near 14.7:1 air/fuel ratio. Also 14.7 is a air/fuel ratio that on paper should make the most horsepower, but it does not make the most horsepower on the dyno or in the field.
Essarex
Pro
Alan is right. On the dyno and in the field, many factors play into how well the air/fuel mixture gets blended. Because of imperfect blending, there will be molecules of O2 not mixed with fuel, when using a 14.7:1 ratio. So, for max power, usually the ratio is set to 12:1 so enough "extra" fuel is available for every single O2 molecule. to get utilized.
Speaking of dynos, on a dyno a vented airbox lid will make more power everywhere, based primarily on the fresh cool air it receives compared to air drawn around a stationary sled's engine. As Knapp said, in field once underway, the fresh air advantage is given up and the loss of resonance is inherited.
Speaking of dynos, on a dyno a vented airbox lid will make more power everywhere, based primarily on the fresh cool air it receives compared to air drawn around a stationary sled's engine. As Knapp said, in field once underway, the fresh air advantage is given up and the loss of resonance is inherited.
aceltx09
Expert
Alan, have you tested the ram air lid against your mod box. Are they equal in gains? I'm not arguing that these sleds run 14.7:1 I thought they did but if they are already running lean and more air is added without fuel, is the engine in danger of running to lean???
jaydaniels
TY 4 Stroke Junkie
- Joined
- Dec 10, 2008
- Messages
- 654
- Location
- Bedford NS Canada
- Country
- Canada
- Snowmobile
- 2017 Sidewinder RTX
Ram aid lid
Has anyone tried covering off the bottom of the airbox stock opening and running the ram air lid? That may actually provide a 'ram air effect'. Just a thought.
Has anyone tried covering off the bottom of the airbox stock opening and running the ram air lid? That may actually provide a 'ram air effect'. Just a thought.
Grunter
Extreme
I can't speak for others....after installing Ulmer's box the rev's went into the limiter. After re-storing rpms or revs by adding weight(within 2 hours) I went from 103mph to 113mph(gps) then 2 days later a bit more fine tuning & testing and got 116mph(gps). And I know there's a little more left to go and get...So I'm a believer! A stock APEX LTX used to beat me(106mph) and now he's not even close anymore! I could not believe it! It's interesting to hear the comments about the fix & Ulmer combo...I was wondering about that myself and never tried yet...I'm running +13 on the pod!
catchmeifucan
Extreme
running both, was out 2 weeks ago and pulled 129 on dreammeter, still pulling, but coming into turn so i slowed, running +10, and pc3 but at stock settings. first run of year so had last years and this years gas. oh yeah, put a sc4 121 with extensions under it. this was my trial run for the suspension.
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