Boost 101

[Tavon]

hey there fellas! I'm gonna throw it out there right away so everyone understands that I am new to this and want to learn. I'm a black man living in Iowa and new to this whole idea of snow. I came from the inner city of Memphis. Black people aren't supposed to like snow, right? I went out with a friend one winter and got hooked. I've raced around on street bikes for a long time but never in snow. So I bought an older Yamaha Nytro and thought I could learn a bit about boost. I bought a MPI supercharger(180 kit) from a cat out here that used it out in the mountains. I ran it last year and instantly became addicted to the idea of boost! Up to this point I was just a rider but I thought I should understand a bit more about how boost works so I can safely add more without harming the sled(engine or other). So I want to add more boost. I was seeing 6-7lbs on my setup. I want to see 10lbs this year. To prepare I have added a head shim. MPI has an upgrade kit with an intercooler and different pulleys. Can someone please explain the basics of the intercooler and how that relates to boost? When is it needed because I don't' have one now and it seems to be ok. This kit is expensive so I'm looking for other alternatives. A friend told me if I just change the pulley combo I can get the boost I want but will need to watch the temp as the sc will produce more heat which can kill the engine. If I change the pulleys and add cooling can I safely run 10lbs? Is there an easy way to adjust boost, up and down as needed, on the SC?

 

[MrSled]

Inner-cooler cools the air charge coming out of the blower... the blower turbo compresses the air and if you have ever felt your air tank from after the air compressor ran and filled the from empty the tank will be warm... warmer air bigger molecules.. colder air smallee molecules.... you need more or do you get the idea?

When you ran at 6 to 7 lbs the charge is not as compressed as 10 to 12 lbs..

 

[Yamadog]

Mr Sled is correct and your idea of adding more cooling is ok but flawed. The heat generated inside the cylinder as the charge is detonated is what you are cooling down with more heat exchanger or radiator, by adding an intercooler you cool the air charge entering through the intake so there is smaller molecules therefore more air molecules per lb of boost. The engine itself won't have a cooling issue just the charge forced into the cylinder. Changing the pulleys will drive the blower faster creating more boost but the efficiency or result is lowered by expansion in the molecules.

The challenge on a sled is there is already a lot of junk under the hood and making one that works, fits and can keep the blower location along with fit onto the throttle bodies is the challenge.

 

[Tavon]

So if I understand you correctly, cooling down the heat in the cylinder, with tunnel cooler, should help keep the sled from overheating, correct? And the intercooler will help create more boost more efficiently than changing pulley combination by allowing more oxygen to enter? To address the temp of the water cooling the engine, is this something that I don't need to worry about with a boosted sled? I thought it made sense that the SC would create more heat in the engine and the radiator would need to be upgraded. so my budget wont allow for the intercooler right now which is a good thing because other posts are telling me that the fuel system cannot handle the extra boost I want. I think I will save up for next year and buy the intercooler and an upgraded fuel system and join the big boy boost club, ha! Laugh all you want homies but I'll catch onto this soon but in the meantime I appreciate you'alls help. Peace Out!

Tavon.................

 

[nos]

no sweat Tavon....you're not alone. for every member on here that really understands boost there are probably 30 more just like you and I that need their help. I thought I might note that while in theory the intrecooler cools air allowing more oxygen is correct it is not because the molecules are any smaller.The air is cooled which makes them more dense. Warm air excites the molecules making them more active and taking up more space. At lest that was how it was explained in organic chemistry . Either way , cooler air will provide more oxygen which means more boost, more efficiently.

 

[MrSled]

Good read: http://www.enginebasics.com/Advanced Engine Tuning/Intercooler.html

 

[thor452]

great read