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Thread: Cheap power

  1. #11
    Senior Member DeadPixel's Avatar
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    I have my governor turned down to 4k from 5k and it takes off softer. I will mark out a start and stop for my bike from a dead stop and we're ever my bike reaches 3,500 with both the governor set at 4k and 5k. I will also time the runs. I can go-pro this if you like. I will put the stock carburetor back on for this. It will take me about a month as my bike is at my in-laws. My bike has a few mods but nothing that will effect the outcome. I only have a few hours on my mini so maybe my butt dyno is wrong. I will do 3 runs, back out screw and do 3 again. We will settle this with a video!

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    HP = rpm * torque / 5252

    Peak torque 6.5 Predator:
    (2500 RPM * 8.1 ft-lbs.) / 5252 = 3.8 hp

    Peak governed rpm 6.5 Predator
    (3800 RPM * 8.1 ft-lbs.) / 5252 = 5.86 hp

    Peak adjusted governor 6.5 Predator
    (5000 RPM * 8.1ft-lbs) / 5252 = 7.71 hp

    Peak ungoverned 6.5 Predator
    (8000 RPM * 8.1 ft-lbs.) / 5252 = 12.33 hp

    Math governs the universe folks. Twice the power at 5000 RPM given the same torque. Obviously the torque curve would fall off, so these numbers aren't exactly right. Notice that peak torque is only at about half the max horsepower of the engine, but the engine keep producing power because power trumps torque.

    Adding RPM does add horsepower. It does not add torque. People are confusing power with torque. This is why Formula 1 V6 engines that only displace 1.6 liters can make 870 hp because they spin at 15,000 RPM. but they' never have the torque even in your average Chevy pick up truck.

    NOTE: This assumes you will change valves, springs, rods, cams an anything else needed to make safe use of higher rpm. As I stated earlier you can't get something for nothing. Time. Money. Power. Pick two out of three. Please understand that we're just talking about the math and not how the engine will deliver the power reliably. That is another thread altogether. I hate qualifying everything I say about something.
    Last edited by BWL; 03-17-2018 at 02:37 PM.

  3. #13
    cheezy1's Avatar
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    And with stock valve springs...you may remove the governor and increase rpm...but they start to float about 5400-5600...you still have around 7hp or slightly more according to the above reference till they float and you lose power. Thanks for making my point guys.

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    Yes, they do start to float. We all, well, thanks for stating that for those who don't know. However, anytime you modify one thing, you will have to make changes elsewhere for various reasons. This should go without saying. Do you think Formula 1 race cars spinning at 15,000 RPM have valve float issues? Of course! That's why they use pneumatic valves. There isn't enough spring pressure in the world to control that much RPM. That still doesn't change the basic fact that they are making 870 hp at 15,000 RPM on a 1.6 Liter engine.

    How engines work at higher RPM is a totally different question than if the engine makes more power at higher RPM. When you start going beyond the basic question then that's another thread all together. You won't lose power because if you're building the engine properly, you will account for that, but that is a discussion that goes beyond what the original post. The math still stands.

    This thread has long since diverged from the original post how to make cheap power. There is no such thing as cheap power. It will cost you either time or money. Often it takes both to make it happen. Please let's stay on subject.

    Cheap power comes through a combination of time and money. In the end there is nothing cheap about making power. Again Formula 1. They have a lot of time, a lot of money, and they make a lot of power: 870 hp, with 15,000 RPM on 1.6 liters. And time here is really synonymous with skill. I mean how many people a really grinding their own cams anymore?

    Time. Money. Power. Pick two out of three.
    Last edited by BWL; 03-17-2018 at 02:45 PM.

  5. #15
    cheezy1's Avatar
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    Exactly...fast ain't cheap...and cheap ain't fast.

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    Quote Originally Posted by cheezy1 View Post
    Exactly...fast ain't cheap...and cheap ain't fast.
    Oh, I see what you're saying! We're actually agreeing. Stinking words!

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  9. #17
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    Quote Originally Posted by DeadPixel View Post
    I have my governor turned down to 4k from 5k and it takes off softer. I will mark out a start and stop for my bike from a dead stop and we're ever my bike reaches 3,500 with both the governor set at 4k and 5k. I will also time the runs. I can go-pro this if you like. I will put the stock carburetor back on for this. It will take me about a month as my bike is at my in-laws. My bike has a few mods but nothing that will effect the outcome. I only have a few hours on my mini so maybe my butt dyno is wrong. I will do 3 runs, back out screw and do 3 again. We will settle this with a video!
    You know what would be really cool? Mount a camera with a view of the linkage to record governor behavior in different riding scenarios. The best example would be a full throttle run from a stop. You should be able to catch when the governor pulls off full throttle or if, like you said, full throttle even occurs. You would need a good view of the top of the throttle plate shaft. You would even be able to see the governor allow for more throttle when the load demand increases, like if you were already at top speed and started on an uphill. The sound of what's going on is already there, video would just verify the actual throttle position.

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  11. #18
    Senior Member DeadPixel's Avatar
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    I would have to relocate my gas tank. Maybe I could figure out something.

 

 
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