How to move peak horsepower higher?

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johnef
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How to move peak horsepower higher?

Post by johnef » Mon Apr 16, 2018 1:04 pm

Im building a 1098cc gsxr1000 (4mm overbore). The factory head has 30mm Titanium intake valves, and 24mm titanium exhaust valves, 44mm throttlebodies.
Factory cams are 0.370" intake and 0.350" exhaust.

I have figured looking through several motorcycle specifications that intake valve area represents 33.5% of bore area on average. That would put new valve size at 31.5mm.

Would it be correct to base my new choke point of 88% based on the new hypothetical valve size? Even though i will keep the intake valve size at 30mm. It being potentially valve limited would it be better to move choke point closer to valve to maintain diverging angle?

I was looking to push peak horsepower from 12500 RPM to 13500 RPM,what would be the best way to accomplish it? Port length, port taper, camshaft duration?

Walter R. Malik
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Re: How to move peak horsepower higher?

Post by Walter R. Malik » Mon Apr 16, 2018 3:19 pm

I would shorten the intake runner length some and make the exhaust pipe slightly larger.
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englertracing
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Re: How to move peak horsepower higher?

Post by englertracing » Mon Apr 16, 2018 3:26 pm

Agree on shorter intake and bigger headers,
Can you put more Cam lift and a touch more duration

johnef
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Re: How to move peak horsepower higher?

Post by johnef » Mon Apr 16, 2018 4:44 pm

Would enlarging from choke point and all the way back to throttle blade aid in shifting power? And from throttle blade to the velocity stack? I have an existind sidewinder. Could i shorten the first step and leave CSA alone?

I can have cams ground to whichever spec i want. What are the recommendations?

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Re: How to move peak horsepower higher?

Post by Desertrunner » Mon Apr 16, 2018 5:24 pm

John would you happen to have any flow bench numbers for the heads? I would be interested to do some maths on them.

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