Turbo YZ

350 replies to this topic
  • grayracer513

Posted May 17, 2012 - 11:20 AM

Not according to the calculations I ran using a standard compressibility factor for dry air. That factor is 0.915, so it doesn't effect the results much at low pressures, anyway, but you see the numbers I came up with. Any substance that resists compression will react in a non-linear manner as to density under pressure. A grossly exaggerated example would be a cubic foot of wood. How much would the volume change under 2 atm? Very moist air compresses considerably less than dry air, too.

The Ideal Gas Law assumes the existence of a gas with no volume and no interactions with other molecules. As a result, it's most accurate with monoatomic gases at high temperatures.

I "cheated" a bit and used a favorite online calculator that proves handy for this sort of thing. Last time I checked it, is was accurate. See what you think:


  • HeadTrauma

Posted May 17, 2012 - 02:50 PM

I see what happened. The calculator uses psig as an input where you entered psia. 14.7psig to 29.4psig represents the 1.5 times difference your numbers reflect. 14.7psia to 29.4psia is the 2 times increase I was scratching my head over. :cry:

  • yz450fcranker

Posted May 30, 2012 - 02:29 AM

all these calculations for an intercooler?
well at least different intercoolers make a difference depending on quality

  • grayracer513

Posted May 30, 2012 - 06:43 AM

I see what happened. The calculator uses psig as an input where you entered psia. 14.7psig to 29.4psig represents the 1.5 times difference your numbers reflect. 14.7psia to 29.4psia is the 2 times increase I was scratching my head over. :cry:

That's a good point, especially at such low pressures, but the principal is the same nevertheless. Gases offer progressively greater resistance to increased density as pressure increases, and they can't be compressed indefinitely. Anyone who has worked with suspension systems like motorcycle forks for a while is quite familiar with that, as the captive air within the fork adds to the spring rate in a sharply progressive way. So you don't get a doubling of air mass by doubling the pressure. At low pressures like going from 1 to 2 atm absolute, it comes close, but not quite, and the increase in mass per increment of pressure increase drops off as pressures rise.

  • yz480doinwork

Posted October 03, 2012 - 08:07 AM

Just thought id give you guys an update, this summer I found an output stator, and I now have an intercooler and intercooler fan. I sized up my whole filter/intake and charge tube system. Went to the dunes a few weeks back and the improvement was amazing. The bike pulls incredibly harder. It likes to stomp on full blown mod CR 500s that probably weigh 100 pounds less than me. I was running at 18-22 pounds, I am thinking about taking my efficiency further with bigger valves, cnc head porting and possibly Carb porting. It would be nice to have the same horsepower at about 15 pounds. Anyone have any advise on efficiency mods I could do?

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  • FinchFan194

Posted October 03, 2012 - 09:23 AM

Any videos of this thing ripping?

  • yz480doinwork

Posted October 03, 2012 - 11:42 AM

Any videos of this thing ripping?

A buddy of mine has some, he's a little slow getting them to me. I will post them asap

  • yz480doinwork

Posted October 03, 2012 - 03:18 PM

here is a video from early last season, it has came a long ways since then, but you can get an idea

Posted Image

  • Bosco83

Posted October 07, 2012 - 09:47 PM

Sweet build and I'm impressed you didn't give up after all the issues it was giving you with tuning at first. Did your original welds hold up that everyone was giving you grief over? I can't wait to see some video with your new intercooled setup!

  • yz480doinwork

Posted October 08, 2012 - 05:26 PM

I have not had any problems with my ugly welds! I do have problems though, with the silencer gasket. I am using the stock silencer gasket and pipe end as a joint because i could not weld Ti to steel. I also thought it would be a good place for things to flex, to prevent the pipe from cracking. I have went through three or four of those gaskets, the exhaust pressure just eats them away. Does anyone know where i can get a better quality gasket? I know you can get solid copper joint gaskets for yamahas 4 stroke sleds. I haven't had any problems with the actual header gasket.

  • Azza1980

Posted July 30, 2013 - 12:22 AM

Hey just wanted to no are you still useing the stock kehine carby

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