Stepped Cylinders

I read somewhere that the reason for the thicker walled cylinders was for strength. If the cylinder was struck during a crash the weak area was where the exhaust ports were cut in - the cylinder would distort. They first added extra material around the exhaust area and left the bottom thin for weight savings, then later just made the whole lower section a uniform thickness. Is this entirely untrue?

I guess the story about strengthening the cylinder by leaving it thick-walled is true, although I have never experienced any crack around the exhaust port area of thin walled cylinders. Some say it was occassionally inflicted even without a hard landing, if e.g. the engine was overheated (too high nitro %, poor cooling etc...)

The weight reduction with the groove may not have played an important role in the development of the design: just think about the latest cylinder shape which is thick-wall, and can be machined with fewer steps i.e. shorter production time and lower cost.. The groove was made there probably for the earlier honing machine, as long as it was in use.

I really need to get one.....
http://www.modelenginecollecting.com/Cox%20Web%20Material/Cox-Book.html

WingingIt74 wrote:I really need to get one.....
http://www.modelenginecollecting.com/Cox%20Web%20Material/Cox-Book.html

Me too! I've wanted it for years but just never pulled the trigger.

I have one and read it with mixed feelings.

At least the TD family - my favorite, and maybe the most famous COX engines - is discussed in less than 2 pages out of the 68. For me important information like production period of tapered wall design, various piston and rod designs etc. are still missing. It is certainly not to be blamed on the authors who looked into every tiny corner to collect the information still available, but in general the depth of information varies a lot accross the book.

Tons of pictures on engines with reference numbers to sub-versions, without explaining the technical difference between them.
But if you have the 35 bucks, you still may like it.

If you re-read the article, it clearly explains why the thicker cylinders. it was never for strength or weight reduction.

The Cox book is missing a lot and is not 100% accurate, but it's the only show in town and well worth the money to a die hard collector or enthusiast.

WingingIt74 wrote:When where they produced? What bypass/boost configurations can you find on them?

I have the handbook and I don't think it specifically mentions the different configurations, although if you go through the manual and check out all the different engine configurations you could figure it out. I am pretty sure they were made in almost every possible configuration. I have personally seen or held the following stepped cylinders: #1, #2, #3, #4, #6, #7. I don't recall seeing a #5 or a #8 but I am pretty sure they made them. In my opinion, the black widow with the stepped #1 is the most desirable of the BWs. Just my opinion. Andy