Jump to content

jbooker82

Members
  • Posts

    6,306
  • Joined

  • Last visited

  • Days Won

    1

Posts posted by jbooker82

  1. My banshee currently has Avenger standard length a arms with 2in 3 out wheels. The shocks are Works dual rate with remote rez.   I am in the process or rehabbing it after a long storage period. The shocks are leaking oil so they will need rebuilt.   I purchased new tires with the stock off set of 3 in 2 out so the wheels wont be dished out so bad.

     

    I was looking to upgraded the A arms to a +2 width.  So my question is long travel worth it on a trail / dune machine that doesn't really get jumped?  If I stayed with standard travel I would upgraded the arms and have my current shocks revalved.  Where as if I went LT I would also have to get new front shocks.

  2. Gauges that use one hose and a bunch of different adaptors are not going to be real accurate.  The adaptor is hollow and that extra hollow space is added volume to the combustion chamber. Look at how much of a difference a cc or two makes when shopping for dome sizes. The same is said when doing a compression test. Snap on gauges with the proper hose has the Schrader valve in the very tip of the hose so there is no added volume.

  3.  

     

    Energy efficiency[edit]

    Once ignited and burnt, the combustion products—hot gases—have more available thermal energy than the original compressed fuel-air mixture (which had higher chemical energy). The available energy is manifested as high temperature and pressure that can be translated into work by the engine. In a reciprocating engine, the high-pressure gases inside the cylinders drive the engine's pistons.

    Once the available energy has been removed, the remaining hot gases are vented (often by opening a valve or exposing the exhaust outlet) and this allows the piston to return to its previous position (top dead center, or TDC). The piston can then proceed to the next phase of its cycle, which varies between engines. Any heat that is not translated into work is normally considered a waste product and is removed from the engine either by an air or liquid cooling system.

    Internal combustion engines are heat engines, and as such their theoretical efficiency can be approximated by idealized thermodynamic cycles. The thermal efficiency of a theoretical cycle cannot exceed that of the Carnot cycle, whose efficiency is determined by the difference between the lower and upper operating temperatures of the engine. The upper operating temperature of an engine is limited by two main factors; the thermal operating limits of the materials, and the auto-ignition resistance of the fuel. All metals and alloys have a thermal operating limit, and there is significant research into ceramic materials that can be made with greater thermal stability and desirable structural properties. Higher thermal stability allows for a greater temperature difference between the lower (ambient) and upper operating temperatures, hence greater thermodynamic efficiency. Also, as the cylinder temperature rises, the engine becomes more prone to auto-ignition. This is caused when the cylinder temperature nears the flash point of the charge. At this point, ignition can spontaneously occur before the spark plug fires, causing excessive cylinder pressures. Auto-ignition can be mitigated by using fuels with high auto-ignition resistance (octane rating), however it still puts an upper bound on the allowable peak cylinder temperature.

    The thermodynamic limits assume that the engine is operating under ideal conditions: a frictionless world, ideal gases, perfect insulators, and operation for infinite time. Real world applications introduce complexities that reduce efficiency. For example, a real engine runs best at a specific load, termed its power band. The engine in a car cruising on a highway is usually operating significantly below its ideal load, because it is designed for the higher loads required for rapid acceleration.[citation needed] In addition, factors such as wind resistance reduce overall system efficiency. Engine fuel economy is measured in miles per gallon or in liters per 100 kilometres. The volume of hydrocarbon assumes a standard energy content.

    Most iron engines have a thermodynamic limit of 37%. Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18%-20 %.[30] The latest technologies in Formula One engines have seen a boost in thermal efficiency to almost 47%.[31] Rocket engine efficiencies are much better, up to 70%, because they operate at very high temperatures and pressures and can have very high expansion ratios.[32]Electric motors are better still, at around 85 -90 % efficiency or more,[citation needed] but they rely on an external power source (often another heat engine at a power plant subject to similar thermodynamic efficiency limits). However large stationary power plant turbines are typically significantly more efficient and cleaner than small mobile combustion engines in vehicles.

    There are many inventions aimed at increasing the efficiency of IC engines. In general, practical engines are always compromised by trade-offs between different properties such as efficiency, weight, power, heat, response, exhaust emissions, or noise. Sometimes economy also plays a role in not only the cost of manufacturing the engine itself, but also manufacturing and distributing the fuel. Increasing the engine's efficiency brings better fuel economy but only if the fuel cost per energy content is the same.

     

  4. What do most builders use when they epoxy crank cases?

     

    I have an RC car motor / piston port cylinder that I need to fill the intake port in. I am using it on a reed crank case so they normally fill the intake port.

     

    The the one I have looks like it was filled with a grey liquid because it was smooth on the surface. It didn't look like it was packed with a putty.

  5. What are my options above a 65.5mm bore. I have a great port job on these, but I've learned lessons with them as well and right now one side isnt smoking as much as the other so it's time for a compression test.. wiseco is the only trusted piston I know, but they only go over size above that to 66mm. I've been told that's the max. So what's the best option here? Aftermarkets that can be resleeved eventually but are big $$ or find a newer pair of stocks and have them reported, or have the ones I have sleeved (which I don't know how much I trust).

     

    I had a pair of stock ported cylinders re sleeved. It all depends on what you want. The ones I had were a Patriot Racing cylinders. I got them cheap because the stock sleeve had a crack. The cost of the re sleeve job was about the same price as buying a pair of stock cylinders, paying for a port job, then doing the finish bore.  The nice thing is you start out with a bran new set of bores. I went with big bore sleeves because you might as well gain a few CC's while your at it. There are different sleeve sizes options. The ones I had were 66-68mm bore. Some guys say that big bore sleeves choke the transfer ports but my cylinders still had aluminum next to the sleeves so it didn't on mine.  I could see that happening if you go with the larger sized sleeves. With a 66-68mm bore I just ran blaster pistons, and big bore domes with the blaster piston angle. 

     

    I had Patriot Racing do the resleeve job. That way when they are opening up the new sleeve ports they are done correctly since they were the ones who did the original port job.

×
×
  • Create New...