Product Review Article... by Scott Schneider

Our review of the new RCMK RZ254 Evo - Rear Exhaust engine...
You should, by now, be well aware that the engineers at RCMK are always focused forward in engineering products we RC boaters worldwide would love to have. If your desires have been for a "Pull starter equipped", rear exhaust engine that fits where a side exhaust engine you now own resides, or you simply want a newer sleaker boat designed around it...look no further!
What we have here is such an engine. The RCMK "RZ-254 EVO". Based on the now refined and improved S-254 EVO, the "RZ" is that same engine with the cylinder and coil rotated 90 degrees placing the exhaust out over the PTO end of the engine and the carburetor above the starter.
Most of the specifications of the RZ254 EVO are the same as those of the S254 EVO. You can refer to our S254 EVO engine review here.
Most of the specifications of the RZ254 EVO are the same as those of the S254 EVO. You can refer to our S254 EVO engine review here.
** Within the North American market, all RZ series engines are being sold with the mounts shown. Gizmomotors engineered the mounts and has them custom made specific for RZ applications. The magneto-side mount is RZ use specific while the PTO end fits all RCMK & Zenoahs. *See the MGB review of Gizmomotors "Life Time Mounts" for more information (coming soon).
Rubber isolators spacing, "center-to-center" is 5 7/8" - 6". Stringer/rail spacing is 5".
A special "Drop" PTO end mount is avalible as well from Gizmomotors. * It will increase the center line spacing by approximately 9/16 -5/8".
A special "Drop" PTO end mount is avalible as well from Gizmomotors. * It will increase the center line spacing by approximately 9/16 -5/8".
Based on its side-exhaust brother the "S-254 EVO" that has already proven itself on dyno tests exceding 5 HP and a tad over 2 foot-pounds of torque, the RZ should, for a production cast-block integral head rear-exhaust engine, have the most power "out of the box" one can currently purchase.
Another plus is the narrow engine width which will allow placement in the sponson areas of large scale cats.
Hydros and riggers can use sleaker cowling designs with less frontal area offering greater aerodynamics.
One thing that must be taken into consideration with the rear-exhaust engines if retrofitting it in a boat which currently has a side-exhaust engine, is the fact that all of the pipe is behind the engine. This in turn makes for a slightly longer engine-pipe combination (approximately 2 - 2.5" depending on setup). In some cases, especially when using heavy tuned pipes, this can pull the CG (center of gravity) a little bit towards the back of the boat. This can easilly be compensated with a little bit of weight up front or moving the engine slightly forward. In new installations this should pose no problems at all...proceed with setting your boat's CG as you wood with any engine/pipe combination.
* Gizmomotors should have a stainless steel 7/8" header that can use the current "No Leak" type manifolds by the time this article go's live...great news !
Unfortunately I am unable to provide an "On-water" performance report on how the RZ runs at this time. This reviewer is currently building a new rigger specific to the RZ's design attributes and will be doing on-water testing in spring 2010.
* Note: Performance should be very equal to the current side exhaust S-254 EVO and by design hopefully have a tad more!
Happy Boating,
Scott Schneider
Modelgasboats.com Technical advisor
GIZMOMOTORS (Exlclusive US Distributor of RCMK Products)
550 Grove Dr.
Bartow, FL
Phone: 863-533-6060
33830 USA
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Website: www.gizmomotors.com
Bartow, FL
Phone: 863-533-6060
33830 USA
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Website: www.gizmomotors.com