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About PaulHail

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    Anchorage, Alaska

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  1. PaulHail

    Buid a custom metal Gas tank

    I'd just like to thank everyone that's posted on the thread providing information on making tanks. I've purchased a few custom tanks and am glad for those of you that make them. All things considered for having a custom tank built to my specs, the materials, labor and craftsmanship I consider them reasonably priced.
  2. PaulHail

    Tuned Pipe Wave Velocity

    I don't believe the loss in power is due to the shorter pipe needed for cooler exhaust gasses. Our engines convert the heat of combustion into mechanical motion. The more heat we can produce, through the fuel we burn and how hot we can run, the more power we make. Big hot fire, big power. If we over cool the engine, or if the pipe cools the exhaust gasses off, then the heat is not being used to produce power and we're wasting the mechanical energy required to pump the air and fuel through the engine. Insulating the pipe, or running a longer or smaller diameter stinger is a means of retaining more heat in the engine and making more power. But as with all good things, too much of a good thing is a bad thing. If we run our engines too hot, we get detonation and we melt pistons. Even though it is hard to visualize, the tuned pipe is effectively the same device as a turbo supercharger, but with no moving parts. The reason turbos are placed as close as possible to the exhaust ports and the headers and turbos often wrapped in heat tape is so that the exhaust gasses running through the turbine are as hot as possible as that gives the maximum power to spin the turbine, and subsequently the compressor.
  3. PaulHail

    Tuned Pipe Wave Velocity

    Peak rpm, fuel, exhaust temps are just a few of the points we need to consider when designing a pipe. As much as we want to achieve peak power at a given rpm, our engines have to lug the prop off the beach, and run through the engines power band (get on the pipe) to hit peak rpm. Hence a pipe designed for peak power at max rpm will not be the fastest pipe or even a good pipe as you need the engine to be able to accelerate from lower rpm’s to get to peak rpm, i.e. it’s all a trade off. The vacuum David discuses is the purpose of the diverging cones of the pipe, that section of the pipe creates a low pressure to help draw the fresh air fuel charge into the cylinder. The diverging cone or cones are what create a high pressure wave that super charges the air/fuel mixture into the cylinders bore just prior to the piston closing off the exhaust port. As far as getting on the pipe, I think there is even more to it than the power band, the engines dynamics come into play. I know when I raced shifter karts if I took a took a wrong which resulted in me short shifting and getting the engine out of it’s powerband it seemed to take me several revs through the powerband and shifts to get the engines dynamics back in sync. I don’t know if that had to do with the carburation becoming out of sync, the crankcase having some extra fuel, fuel starvation, the pipe having less hot gasses or what, but I could definitely tell the process of getting an engine on the pipe has more going on than just pegging the throttle and waiting for the engine to wind out. Also as David mentions engine mods to timing affect how the pipe works. So the question is, do you do you match engine mods to match the pipe, or do you mod the engine and design and test handfuls of pipes to match the engine mods??? Then you throw in air temperature, humidity and pressure and add in water conditions for the day.
  4. PaulHail

    Power Coating

    I think what Tim is asking is not about putting powder coat on a ceramic or non conductive surface, but rather putting a ceramic vs. a thermosetting plastic coating on a conductive surface.
  5. PaulHail

    The Evil Twin 90 SGX

    Hope your damage was limited from the quake. I feel like Anchorage dodged a major bullet as if it had shook much longer or with a greater magnitude I think we would have had massive devastation.
  6. PaulHail


    Dittos. You're asking for crank failure if you bore out the center of a crank.
  7. PaulHail

    Road Runner 45 OS 46 for sale

    $325 shipped for the boat with engine and pipe in the US. $225 for the boat shipped w/o engine and pipe in the US.
  8. PaulHail

    OPS Collectors

    Let me guess, you already have plans to replace the rotary intake with a blower. A mini nitro burning detroit diesel
  9. PaulHail

    OPS Collectors

    Wow, that's a cool engine. Looks like a miniature jetski engine.
  10. PaulHail

    New to riggers

    Looking at the manual I think there is a difference in the internal bulkheads and the tub might be a different length. Given the reasonable price of the Zippkits I don't think anyone's tinkered with modifying the 21FE with the 21 GT kits available.
  11. PaulHail

    Road Runner 45 OS 46 for sale

    $200 plus shipping Sent from my iPhone using Tapatalk
  12. PaulHail

    Road Runner 45 OS 46 for sale

    Payment received, cowls shipped. Should get there Saturday.
  13. PaulHail

    Road Runner 45 OS 46 for sale

    Cowls are yours, $50 shipped Sent from my iPhone using Tapatalk
  14. PaulHail

    Road Runner 45 OS 46 for sale

    Bottom line, $300 plus shipping.
  15. PaulHail

    JAE History

    Rod, as one returning the hobby from a long absence and in the slow process of building a JAE 91, I'd like to say thanks to JAE and Zippkits for their products. Not only are the JAE kits affordable, the quality is outstanding. As one used to die cut door skin Dumas kits, the laser cut Zippkits are next level. Hopefully your new defib/pacemaker has better shielding from radio interference. With the preponderance of 2.4 ghz devices in modern society that's a bit un-nerving!