to engine builders...
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Cruiser
Joined: Nov 2009
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From: Amarillo, TX
to engine builders...
1) What % mid to upper power increase do you see when rIsing the compression ratio
From 9:1 to 10:1, all else on a stage 2 motor left the same.
2) Same question regarsing a 10% displacement increase?
From 9:1 to 10:1, all else on a stage 2 motor left the same.
2) Same question regarsing a 10% displacement increase?
Tourer
Joined: Aug 2009
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From: Barre,VT
I believe every compression point you go up it's around 3-5% increase in horsepower. Where the horsepower is increased all has to do with the cams and timing! I'm betting 10% increase in displacement will be around the same amount as the increase in compression.
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Yes, except that how you gain the increase in displacement will determine where it comes into play. If you stroke it, the power will be at the bottom of the rev band, and you'll lose (most likely, but not always) a little at the top end. If you bore it, you'll do the opposite. Also, if you bore it, you have room for larger valves, again gaining (potentially, anyway) even more power, again at the expense of bottom end, but you raise the top end power, and gain the ability to rev higher, which is where the real horsepower is. You notice that all the crotch rockets have oversquare motors, and ungodly high redlines (hell, the BMW S1000R has a redline of around 17,000 RPM!), make amazing power for the engine size. It's about spinning out the engine, figure out how to do that, and you've really got something going.
Tourer
Joined: Aug 2009
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From: Barre,VT
I agree with Tekdiver but you'll have to have good quality parts too! Increasing displacement might give you increased weight in your rotating assembly. Not saying .10 or .20 over will give you a huge weight increase but be aware of what materials your putting into the engine as replacements especially in extreme compression situations or Nitrous and Forced induction ala turbo/supercharged applications.
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Cruiser
Joined: Nov 2009
Posts: 157
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From: Amarillo, TX
I agree with Tekdiver but you'll have to have good quality parts too! Increasing displacement might give you increased weight in your rotating assembly. Not saying .10 or .20 over will give you a huge weight increase but be aware of what materials your putting into the engine as replacements especially in extreme compression situations or Nitrous and Forced induction ala turbo/supercharged applications.
Looking at starting with an opened intake and exhaust on an 883C, Andrews N3 cam, Thunder Max, and developing a strong midrange engine from there.
Was originally thinking of going to 1000 cc, but it looks like 1200 would give a lot more torque.
Would try to keep the recip. weight as close to orig as possible as this is a very smooth scoot, and long-term smooth dependability is a real consideration.
Banned
Joined: Sep 2009
Posts: 7,580
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From: The Internet (& Dyer, Indiana)
Adding displacement should increase torque everywhere, unless your cam forces it to one side of the chart or other. Stock cam with added displacement should add torque low (where you spend most of your time at).
Diplacement = torque. Makes my mouth water!
Diplacement = torque. Makes my mouth water!
Thread Starter
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Cruiser
Joined: Nov 2009
Posts: 157
Likes: 0
From: Amarillo, TX
I agree with Tekdiver but you'll have to have good quality parts too! Increasing displacement might give you increased weight in your rotating assembly. Not saying .10 or .20 over will give you a huge weight increase but be aware of what materials your putting into the engine as replacements especially in extreme compression situations or Nitrous and Forced induction ala turbo/supercharged applications.
Looking at starting with an opened intake and exhaust on an 07 883C, Andrews N3 cam, Thunder Max, and developing a strong midrange engine from there.
Was originally thinking of going to 1000 cc, but it looks like 1200 would give a lot more torque.
Would try to keep the recip. weight as close to orig as possible as this is a very smooth scoot, and long-term smooth dependability is a real consideration.
Any suggestions on "Best" way to do this? Head work?, specific parts?, etc.
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