Sharkey
Well-Known Member
- Messages
- 778
- Location
- Abbotsford BC Canada
ive had this idea rolling around in my head since hpi baited us with the octane and then killed it (and recently there are clues it may not actually be dead). i figured there had to be a way to build a functional gas savage, not something with a 23-30cc engine crammed in it. i spent a few months searching around and i found an engine that would work, and recently i ran across a deal too good to pass up on a box full of savage parts. i ended up building one complete savage x rtr to sell, and a complete rolling xl chassis, the basis for my build.
the truck itself is pretty basic, i call it an xl, however its actually closer to an x with xl chassis plates. its using the older non bulletproof diffs, however ive spent a bunch of time shimming them, i figure since they seem to hold my picco fine in my other savage they should be ok in this. i built a bulletproof 3 speed, and its running hd dogbones and a 17mm hex hub conversion. im using some xtm shocks i previously ran on my other savage.
now for the engine. it took me a bunch of research to find what would work. i had a few options, i ended up with an evolution 15gx. its a 15cc (0.91) gas 2 stroke. i was considering the 10cc version, however i figured hpi was building the octane with a 15cc, so i should use the larger engine. aside from more torque, the 15cc version comes with a cast iron sleeve and a ringed piston, so its going to run strong gallon after gallon.
this isnt going to be a simple bolt together, however its not going to be quite as many custom parts as my twin nitro xo-1. it looks like ill need to machine an engine plate and engine mounts, along with a flywheel. i have a couple obsticals i haven't yet figured out, however nothing that serious. my goal with this build is to use as few custom parts as possible, and try to build the truck as close to what hpi could have done with the octane. that being said, im not going to run a whole pile of aftermarket parts, it will have an ofna 250cc mid tank conversion, and the parts needed to get the engine in the truck, but thats about it. id like to make it something that could be replicated somewhat easily.
tonight i started on the engine. likely the biggest issue to sort out is the flywheel and clutch setup. the engine uses a massive 5/16" threaded crankshaft. a typical clutchbell couldnt be used as is, so i got the crank rigged up in the lathe and machined the threaded portion farther down. i found out im able to machine it without too much issue, so ill be machining it so it looks like a little larger version of a typical SG shaft crank. ill be milling a flywheel, and ill run a normal hpi clutch bell.
gearing is another interesting thing. the gas engine has a significantly lower peak rpm and makes a lot more torque, so gearing it up is needed. combined that with the large physical size of the engine and how close the brake setup is i had to come up with an interesting setup. ill be running a brushless motor pinion gear as the spur gear. this is nothing new, its been done for top speed savages. what im going to do different is machine a hub to combined the slipper clutch and the pinion gear so i still retain the slipper. along with that i should be able to run between 14 and 18 tooth clutchbells.
here are a few pics of the engine apart. shown with it is parts from an hpi k4.6/axial 28.
the truck itself is pretty basic, i call it an xl, however its actually closer to an x with xl chassis plates. its using the older non bulletproof diffs, however ive spent a bunch of time shimming them, i figure since they seem to hold my picco fine in my other savage they should be ok in this. i built a bulletproof 3 speed, and its running hd dogbones and a 17mm hex hub conversion. im using some xtm shocks i previously ran on my other savage.
now for the engine. it took me a bunch of research to find what would work. i had a few options, i ended up with an evolution 15gx. its a 15cc (0.91) gas 2 stroke. i was considering the 10cc version, however i figured hpi was building the octane with a 15cc, so i should use the larger engine. aside from more torque, the 15cc version comes with a cast iron sleeve and a ringed piston, so its going to run strong gallon after gallon.
this isnt going to be a simple bolt together, however its not going to be quite as many custom parts as my twin nitro xo-1. it looks like ill need to machine an engine plate and engine mounts, along with a flywheel. i have a couple obsticals i haven't yet figured out, however nothing that serious. my goal with this build is to use as few custom parts as possible, and try to build the truck as close to what hpi could have done with the octane. that being said, im not going to run a whole pile of aftermarket parts, it will have an ofna 250cc mid tank conversion, and the parts needed to get the engine in the truck, but thats about it. id like to make it something that could be replicated somewhat easily.
tonight i started on the engine. likely the biggest issue to sort out is the flywheel and clutch setup. the engine uses a massive 5/16" threaded crankshaft. a typical clutchbell couldnt be used as is, so i got the crank rigged up in the lathe and machined the threaded portion farther down. i found out im able to machine it without too much issue, so ill be machining it so it looks like a little larger version of a typical SG shaft crank. ill be milling a flywheel, and ill run a normal hpi clutch bell.
gearing is another interesting thing. the gas engine has a significantly lower peak rpm and makes a lot more torque, so gearing it up is needed. combined that with the large physical size of the engine and how close the brake setup is i had to come up with an interesting setup. ill be running a brushless motor pinion gear as the spur gear. this is nothing new, its been done for top speed savages. what im going to do different is machine a hub to combined the slipper clutch and the pinion gear so i still retain the slipper. along with that i should be able to run between 14 and 18 tooth clutchbells.
here are a few pics of the engine apart. shown with it is parts from an hpi k4.6/axial 28.
