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Post by ThomasTPFL on Jun 22, 2018 1:40:33 GMT -5
Ahh... not stealth so much, bu I’m working on quieting mine without restricting flow now. I think the airbox is gonna look like Medusa when I’m done.
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Post by ThaiGyro on Jun 24, 2018 4:53:11 GMT -5
I like your thinking reph...here are more tidbits to consider: Your inlet diameter might be more of a tuning issue than many would consider.
I have mentioned prior, that Rotax has this air box thing fairly dialed. They have a single design for a 125cc kart engine. That said, they have 5 or 6 variations of that engine, from mild to wild.
They do use a few different carbs and 3 different pipes.
The thing to look at is that they have two inlet ports to the box and they vary the diameter of those adjusting for intended horsepower, not cylinder capacity.
The mild version 125cc has 15-16 hp, I think. The MAX EVO has 34 dyno tested ponies! More than double.
Just thinking...I am testing my FI setup the same way. Using a 4T throttle body for an engine that makes 12 hp. It's all about stoichiometry!
Hehe!
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Post by repherence2 on Jun 25, 2018 20:41:19 GMT -5
Thanks ThaiGyro for sharing that info! Very interesting. I'm going to brainstorm the multiple port set up. ...the gears are turning. I'm thinking of making 2 block off plates for my modified air box inlet, one with a single port, and the second plate with 2 different sized ports. And then do some testing with each of the 2 plates.
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Post by ThomasTPFL on Jun 25, 2018 22:56:56 GMT -5
If I was experimenting with flow I'd do something like the air vent on a charcoal grill. Old Yamahas actually had a stock airbox that looked like that.
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Post by benji on Jun 25, 2018 23:01:44 GMT -5
If I was experimenting with flow I'd do something like the air vent on a charcoal grill. Old Yamahas actually had a stock airbox that looked like that. so did old cars, like my '75 Ford courier (Mazda b1800). A similar idea would be a damper door, like a spring loaded trap door that opens under extreme vacuum. That way you would only get more flow when the engine needs it, and you could adjust flow w spring tension. |
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Post by repherence2 on Jun 25, 2018 23:32:11 GMT -5
If I was experimenting with flow I'd do something like the air vent on a charcoal grill. Old Yamahas actually had a stock airbox that looked like that. Excellent idea. I will take that into consideration. |
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Post by repherence2 on Jun 25, 2018 23:33:33 GMT -5
If I was experimenting with flow I'd do something like the air vent on a charcoal grill. Old Yamahas actually had a stock airbox that looked like that. so did old cars, like my '75 Ford courier (Mazda b1800). A similar idea would be a damper door, like a spring loaded trap door that opens under extreme vacuum. That way you would only get more flow when the engine needs it, and you could adjust flow w spring tension. Like v-tec for air box intake.  . I like that. |
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Post by repherence2 on Jun 25, 2018 23:36:50 GMT -5
Helmholz is a formula regarding resonation. Those can be used for calculating airbox volumes and subwoofer housings volumes and such. I made my own airbox for the 70mph axis a few years ago. You can find some info in my build thread. Didnt calculate anything really, it was merely for inlet sound muffling. Ran a huge open twin-air foam filter first and with that airbox no jetting changes were needed. Thus no power loss. Only less noise. Lucas2T I just read up on Helmholz resonators. Very interesting. And you are right, that's the Answer. Thanks for sharing that information. |
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. I like that.