CC,

Your optimism about what an engine manufacturer has done or may do is encouraging, considering some of the things that have been done in the past by other well known manufacturers. However, one can never tell what is in the future.

JA

Earlier I wrote:

>I'm suspecting TK has done some R&D resulting in a slightly different approach to heat
>adsorption and dissipation.

OK, maybe it's all a WAG. Just appears terribly risky to change the sleeve, the piston
and plan to offer a button assortment (plus the multiple displacements) if they were not
convinced it would meet their expectations.

Optimistic - yes, but guarded also.

One thing about this motor - it's going to be tough for anyone to argue it's a spot on
clone of any particular motor. Copy cats are boring. TK is making a couple of bold moves
here - let's see how it all shakes out.

Dave,

I found this paper in my library pertaining to ceramic plasma coating of pistons by Mike Hammer. Interesting read about how much coating to apply, where is the best situation to use coatings, how to run the engine after applying coatings, are coatings best for air cooled or water cooled engines, etc. ( www.strappe.com/plasma.html)

Jim

The TK had input from at least 2 very good boat racers that I know of to help them in their engine development.

Dave,

This is some more information about what a sleeve could be made of & how it could be made that comes from Darton, a well known sleeve manufacturer.


"Material Choices:
Sleeves may be manufactured from cast iron, alloyed iron, ductile iron, steel or aluminum. Within the iron category sleeves may be manufactured using an as-cast procedure or a more common "spin casting" process which in engineering terms is by a "centrifugal" die machine. Sleeve quality and consistency are more predictable using the centrifugal process. Darton produces all our sleeves except steel and aluminum using the centrifugal process and additionally Darton uses proprietary machinery to change rotational speed of the casting dies to manage the material compacting and density of certain chemicals within the material matrix. Please refer to material specifications under "Our Services" for specific chemistry and mechanical properties.

Steel sleeves are not normally used except in hybrid installations or where the necessary exits for ultra thin walls in the dimensions of .040 - .060. Although steel tensile strength is generally higher in the ASTM 4-5000 series steels, the mechanical properties of steel are not as well suited to cylinder liner usage without additional processing of the material such as heat treating and/or surface coating. When steel sleeves are treated and coated with hard-chrome or nicasil the sleeve becomes very strong and useful, however, the costs are very high, sometimes as much as 4-5 times more expensive than ductile iron. Cast, alloyed, ductile or steel sleeves are all acceptable for use in iron or aluminum blocks although different installation procedures are required in each circumstance.

Aluminum sleeves are considered specialty items and can only be practically used in aluminum block, dry sleeve applications. The main advantage of aluminum sleeves is weight saving and generally equal rates of expansion. Although aluminum may reach tensile strengths over 50,000 psi, the elongation in aluminum is not suitable for a wet sleeve application. In addition, aluminum sleeves will require bore coatings such as nicasil to perform as a cylinder liner. There are some materials of aluminum structure referred to as "MMC" or metal matrix which incorporate amounts of silicon and carbide to improve or permit piston ring abrasion resistance however, machining of this type of material is difficult and expensive.

Copyright ©2006 Darton International Incorporated. All rights reserved."

The information falls in line with present day technology that is used for cylinder liners.

JA

Getting in to the "design" aspects of the TK, I wonder if their 35mm. piston is a crown coated CY piston, or their own design? The reason I ask is, if they went with their own piston, they could have produced it with a higher pin placement in order to use a 55mm. long connecting rod. This would have produced a 29.6mm. stroke ( as it has ), but with a better 1.85:1 rod/stroke ratio. As their cranks are a unique stroke length anyway, I don't think it would add anymore cost, unless they wanted to use a CY ( existing ) piston.

Thinking out loud ...

FYI The TK27 has a 28mm stroke.

Good thinking out loud. The new rod I'm building has a 2.155" (54.695 mm) center distance with the 1.102" (28 mm) stroke. That's a still better 1.95:1 ratio.

JA

I have a tk motor ran it for the first time yesterday.

Out of the box its the best "stock" motor ( i have fitted the pro mod piston) I have used. It was run in a Lazer 45 that i pulled a full mod 29.5 gizmo zenoah out of to test it.

My results are that it was not as strong as the full mod zenoah 29.5 as it wont pull the same rpm with the same props in a boat with the same trim. However for $375 opposed to $520 respectively for the engines the TK is in opinion excellent value.

I used a hotpipe with internal stinger @12.5 inches. Used some pretty big props, Brent daily 7016 / 3 410, CoCr BJ1 and SIM4 props and saw RPM in the mid to high 16,000 range.

I will be testing with a 3 bladed version of the 4 blade prop as i feel this will suit the motor in stock form.

The out of the box TK motor in my view outperforms any stock zenoah, any stock RCMK / 254 EVO OR K30 and is probably on par with any well modded 26.

regards

Ben

My apologies Dave. Of course those dimensions would not produce 27ccs. I was mixing up the TK 29.6 crank that Gizmo uses for his 30 Zen ( GZR ) eng., with the standard stroke TK crank.