Engines > Your Own Design
.90 cu in, 30,000 RPM, 7.2 HP custom built nitro engine
strictlybusiness1:
These are some photos of my custom built .90 cu in engine that I used to set straight away records with. All parts in the engine are custom made including, machined from solid crankcase, hardened steel front end, ceramic hybrid bearings, chromed plated cylinder, machined piston, hardened steel roller rod with rollers & retainer, automatic fuel metering carburetor, machined tuned pipe, etc., etc., etc.
There is so much detailed information & photos, it is hard to decide where to start. Many carefully designed fixtures & tooling were built on manual machines to enable the building of these engines. I will answer any question asked about the technical information used to build & test these extremely reliable high performance two cycle engines.
Jim Allen
ths:
Looking at this, the word 'golly' comes to mind, used as a metaphor of course. Nice gear, looks well made. How do you factor in the chroming of the cylinder when making the piston? I take it that it is lapped until the fit is to spec? Hugh.
Niels Abildgaard:
Hello Jim
More music please.
What kind of beer can I bring You?
strictlybusiness1:
No lapping compounds of any kind, including non-embedding types, should ever be used to fit a piston in ABC or AAC engines. Cylinders are machined with their taper amount & then chrome plated with approximately .0015" thick chrome/ side. The cylinders are then ID ground & each high silicon piston is machined to fit with a particular amount of crunch. The pistons also have a taper cut on their OD down from the top for a distance of .100". If done correctly there will be a distinct wear band where the piston rubs against the bore. This wear band remains there throughout the life of the piston, liner combination & it indicates that this is the area where the sealing takes place. Pistons are machined from RSA-444 T6 (30% silicon aluminum) bar stock with crystalline coated diamond tooling. Cylinders are made from C360 free machining brass, C544 Phosphor Bronze & 4032 silicon aluminum.
The photos show a typical chroming fixture, the piston's wear band, the fixture used to machine & ID grind tapered cylinders.
Jim Allen
JMcRae:
Beautful work! may I ask what the connecting rod is made of?
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