Power boost for kart racing?
 

I hope none of my competitors are reading this, but I have been wondering of various ways to boost power for kart racing. It uses a 2 cycle Yamaha 100cc engine.

Are there fuel additives, in-line valves, etc. that can effectively boost the power. I'm estimating that I am running between 25 and 29 HP.

This immediately comes to mind.

http://a1020.g.akamai.net/7/1020/793...uct_couple.jpg

emcon5, very, very funny. I have been trying that for a year with no results so I have given up. I'm 30 lbs over weight so how much is that in HP loss? Again, very, very funny.

You should be able to give yourself an rough idea by figuring out your power to weight ratio. If you and your kart weigh 400lbs, and your HP is 25, you have 16lbs per HP. Losing 16 lbs would have roughly the same effect as adding 1 HP.

There is more to it than that, since more power makes you go faster forward, but lighter weight makes you faster in every direction.

Tom

Razor,
I looked at your karting page....you don't look like a cheater!
But if you must, why not mix a lot of Nitromethane into your KT 100's fuel. The motor won't live very long with a load, but you will like the kick in the back you get.
A good brand to try is Powermist.
Jet your carbs *very* rich to start, and work from there.

Doug, know who to cheat and cheating are two different things. Having said that, thanks for the info.

I'd mill the head a little, put a supertrapp on, change the reed valves, port and polish the head. And ALWAYS run 110 octane of better.


Spent the first part of my life being dragged around motocross tracks by my dad, what else dfo you want to know?

Have you ever used Propelyne Oxide. It is a VP Racing fuel that is an oxegenator. Very very nasty stuff. But it knocked 2 tenths of a second of of a "freinds" 1/4 mile time at the drag strip. Not sure how applicable it is for Karts but I know that some motorcross guys use it

20% nitromethane mixed with hi-octane gas...

If you really want to get creative, 70% methanol and 30% nitro will work for a while :)

I've seen this stuff blow heads off

Well, just about anything used in excess can cause problems. :rolleyes:

Where did you get the 25 - 29 hp number from?

I used to race a Yamaha KT100 engine in the clutch/open pipe class. Using a direct drive sprocket and a gear ratio I can't remember on a dynojet chassis dyno, the best I ever saw was ~16 hp. This was a locally blueprinted motor, but I don't think anyone ever got much beyond 18 hp using the spec motor rules and some lucky factory cylinder castings.

It appears you have a Yellow Fin blueprinted motor. When was the last time it had a top end rebuild? What about a complete rebuild? What gas do you use? What rpm do you slip your clutch at? Does your clutch engage consistently? At what rpm does your engine's torque peak? What pipe are you running? What length of flex pipe do you use between your header and your exhaust pipe? Do you use a filter inside your airbox? When was the last time your carb was rebuilt? Do you have an egt AND cht gauge? What kind of oil do you use, and what ratio do you mix it in? Do you know how to use data from your gauges to tune your carburetor while driving to optimize power and ride the edge between power and detonation?

Judging by your horsepower estimate, I suspect you can't answer ALL of these questions. If this is the case, cheating in the motor won't make a difference.

How far off the pace are you?

-Steve
'86 951

For everyone's info: nitromethane does not mix with gas. The equivalent to the nitro/methanol fuel mix for gas is di-nitropropane. That and a little propelyene oxide as an exciter is all you need. But first, if you are racing karts and cannot answer ALL of Steve's questions, you are too far off the lead pack to worry about exoctic fuel. Raced karts from age 14 to age 47. Saw it all.

Guys, this thread is a tremendous learning step for me. Thanks. For instance: hunger pains = horse power. Get it? HP=HP.

This is my second year racing and I'm sure that I'm well off the pace of regional and national racers. Last season, my best finish was 3rd at my local track. I managed 3rd place three times out of fourteen races. BTW, I'm not planning on mixing Powermist or anything like that except during practices. A friend of mine keeps telling me to use fuel additives and reed valves and I was wondering if it is even possible.

Jered, do these little two cycle engines have reed valves? Are they in the carburator? If so, how would changing the reed valve help?

Steve, here are the answers to your questions. The 25-29HP was a guesstimate basis information I have read. Is there a way to make a home made dynometer?

Q. When was the last time it had a top end rebuild?
A. Only one of the three blueprinted engines has had the top end rebuilt, but it has not been used yet. It was going to be my main engine this year, but currently is slated as a spare. Hopefully, if I have the time, I will be able to swap all three engines until I find the best one.

Q. What about a complete rebuild?
A. Never. What would that entail?

Q. What gas do you use?
A. Racing fuel provided by the local karting supply store. This is the only source I know for racing fuel.

Q. What rpm do you slip your clutch at?
A. This was a big mistake for me last year. My clutch was slipping too soon and booging down out of the tight corners. I'm going to increase it to around 10,000 rpm to see if that helps.

Q. Does your clutch engage consistently?
A. No.

Q. At what rpm does your engine's torque peak?
A. I don't have a dynometer and could only guess at this like I did the HP.

Q. What pipe are you running?
A. I am using an A2 for this track. It is for medium range tracks, not too short, not too long. I have heard there is an L2 available, but don't know if it's better or worse. Here is a link to a picture of our track. The distance from track out of turn seven to track in of turn one is 120 feet. Total distance is 0.4 miles.

Q. What length of flex pipe do you use between your header and your exhaust pipe?
A. I have not changed this, but used what was available with the used karts I purchased.

Q. Do you use a filter inside your airbox?
A. No. I have a filter on the outside of my airbox.

Q. When was the last time your carb was rebuilt?
A. Only one of the three carbs have been rebuilt and it made a significant difference.

Q. Do you have an egt AND cht gauge?
A. If you mean rpm and temp gauge, I do have one. It's very difficult to tell when the clutch engages because the numbers change so fast. I don't know how to use the engine head temperature gauge.

Q. What kind of oil do you use, and what ratio do you mix it in?
A. I use 3oz of castor and 3oz of synthetic per gallon of fuel.

Q. Do you know how to use data from your gauges to tune your carburetor while driving to optimize power and ride the edge between power and detonation?
A. No.

Again, this is a major stepping up time for me and getting the basics right will make a big difference.