Neurotoxin mods also available for your stock engine
Optional aluminum iso block
can probably count on one hand the number of guys that can take
a stock Zenoah 260PUM and, through tried and true methods and
years of practice, transform it into a full-blown racing engine
capable of pushing a large-scale rc boat to speeds in excess of
70mph, and be reliable. And while there are many people out there
milling away at engines, only a few do it for a living; these
gentlemen are the leaders in the industry and are sought after
for there high-performance modified Zenoah engines.
of the aforementioned engine manufacturers on the racing scene
is TRM, or Toxic Racing Machines, out of Chuluota,
FL. TRM has been modifying gasoline engines since 1990 and working
with Zenoah engines since the late '90s, supplying racers and
sport boaters alike with some of the best engines available on
the market. Owner Alan 'Toxic Al' Gemuendt is the man behind the
latest full-mod G260, the Neurotoxin, and it's
quality and power are of no exception.
Neurotoxin follows a long line of high-performance TRM motors.
The original mod-motor was the G230 Chemical Warfare, followed
by the G231 Screamin' Demon, then the G260 Venom was introduced,
followed by the Neurotoxin. All are race motors and all are race
now you know a little about Toxic Racing Machines, let's take
a look at Al's latest weapon, the Neurotoxin G260PUM.
Neurotoxin G260PUM Full-Mod Race Engine Pricing:
$525 - motor w/ aluminum isolator block
$550 - motor w/ 257 carburetor and aluminum isolator block
$225 - Neurotoxin modifications to your stock G260 motor Carburetor: Walbro 257 Height: Lowest point of case to top of water jacket - 5
1/2" Spark plug used : NGK CMR7H Dry Weight: 3.6 lb Needle settings from TRM: High speed = 1, Low speed = 2 2-stroke oil used: Amsoil Dominator @ 8 oz. per gallon Pipe/header used: 90-degree header, 2" band pipe Radio equipment: (Included) AM pistol grip, 2 channel receiver,
Allen wrenches for working on your motor
start and coil pickup
257 carb and aluminum iso block
Neurotoxin arrived in the original box that Zenoah ships their
stock engines in. Packaged with the engine are a number of items;
the Zenoah owner's service manual, the velocity stack which will
not be used, a few machine screws and washers left over after
the aluminum isolator block was installed, and a spark-plug socket
wrench. The overall appearance of the Neurotoxin isn't that much
different from any other Zenoah mod motor, and companies usually
personalize an engine with their logo on the pull start cover
and sometimes on the top of the water jacket. The Neurotoxin features
the TRM skull and crossbones graphic to set it apart from other
a look at the exterior of this engine, we'll first examine the
carburetor; I chose the option of a standard Walbro 257 carb.
It does not have a choke or primer bulb yet starting is quite
easy if you place your finger over the intake and slowly pull
the starter until fuel draws up to the carb. The 257 has a high
and low speed needle and they are set at 2 turns out on the low
and 1 turn out on the high. Attaching your throttle linkage is
up to you; I chose a bellcrank that bolts to the motor mount.
Behind the carb is the isolator block, used to keep power-robbing
heat from soaking the carb. Plastic or delrin blocks can warp
and create air leaks so this Neurotoxin was ordered with the optional
aluminum iso block. I highly suggest you purchase one when buying
your new motor because not only do they keep heat away and eliminate
air leaks but they also come with teflon gaskets that will never
tear and probally never leak, as long as you keep the carb bolts
with a majority of modified Zenoah engines, the coil and pullstart
are stock parts. The coil works well for the amount of power a
modified engine makes up to 18,000+ rpms.
Neurotoxin's internal modifications are what make it a true race
engine; Al has spent countless hours finding a balance between
performance and reliability with his motors and this one is no
exception. One area that gets attention is the exhaust port; its
been raised 2mm to increase timing and widened 2mm to increase
volume. Al uses a unique style of widening the exhaust port more
on the top than the bottom. Another area that has been modified
is the piston; it's been relieved under the wrist pin and the
skirt to remove excess material and lighten the piston, freeing
up some horses due to less rotating mass. Countless hours have
gone into testing to find the perfect amount of material to remove
from the piston because there's a fine line between too light
and too heavy. But just how much weight is removed is a secret,
and TRM has the numbers right-on and removes the exact same amount
on each Neurotoxin that goes out the door.
with increased compression, the Neurotoxin gets a trued crankshaft,
balanced flywheel, and gets made over with stainless steel bolts,
flat washers, and lock washers. A stock crank-seal is used instead
of a zero-drag seal. Why? Because the minute amount of reduced
friction experienced once the engine gets fully run in is not
worth the air leak that zero-drag seals create.
Installed in an Aeromarine Avenger Pro
Neurotoxin with 90 degree header and 2" band pipe
the motor is ready to bolt in, there are still a few parts you'll
need to complete the installation. The first is an exhaust system.
This area is really up to your personal preference but I would
advise against power-robbing wrap-to-center or wrap-forward headers,
as a 90 to 105 degree header is the shortest route to the pipe.
Your pipe choice as well as the total length of the exhaust will
play a key role in how the engine performs. TRM recommends a 2"
band-pipe to give the best overall performance throughout the
powerband. The length from the exhaust flange to the center of
the band on the pipe should start around 13" and be shortened
until there are no more gains in performance noticed.
I ended up at 12.5" from the flange to the center of the
band which seems to be a good compromise between rpms and torque. A gps and
a tachometer are helpful tuning devices and should be utilized to aide in finding a good exhaust length.
item you'll need is a pair of Zenoah-style motor mounts. My favorite
style are the quick-change mounts which allow you to remove the
motor by loosening four nuts. A bellcrank for your throttle is
a necessity when it comes to making the throttle hook-up easy.
Most bellcranks mount to the rear motor mount and effectively
make a 90-degree turn in the linkage. I suggest staying away from
a throttle cable that can flex and go with a beefy 4-40 pushrod.
Other small items required, assuming you have a boat ready for
the engine, are a collet, fuel filter, and plumbing lines for
gas and water.
installed the Neurotoxin in an Aeromanine Avenger Pro for this
review. The pipe used was a B.H. Hansen 2" band pipe, the
header was a 2" drop, 90-degree Hansen as well. Overall length
from the exhaust flange to the center of the band was 12.5".
My prop of choice for the Avenger is a 6717x3 piched to 420.
Head with TRM id
Internal head modifications
Carb w/ aftermarket throttle arm
in any Zenoah engine is the key to a long life-expectancy, and
especially so with a full-mod engine. I mixed my gas with 8 ounces
to 1 gallon of Amsoil Dominator and ran the engine at a no more than half-throttle for 2 tanks of fuel. During the 3rd tank of fuel, continue varying the throttle, with very brief full-throttle blips. Varying
the throttle is crucial in order to get temps up but not for extended periods.
The fourth tank should be right on for full throttle running and tuning for optimal performance.
order to get the best numbers possible from your Neurotoxin, you
should expect to put at least 2 gallons through it. Afterwards,
your rpm's, mph, and overall torque will increase noticeably.
This is due to possible glazing on the ring that gets burned off
as the engine runs-in. I experienced almost a 5 mph increase towards
the end of the 2nd gallon, doing nothing other than running
the engine was run-in and tuned for performance, the real power
produced by the Neurotoxin began to show. Even in the heavy offshore-style
Avenger, I was consistently putting down mid-to-upper 50s in race
trim, which basically is setting the hull up for the rough and
choppy water conditions experienced when multiple boats are racing
in an oval pattern. The objective is to keep the nose down to
avoid blowing over. Overall top speed is reduced some in favor
of better handling. Some of the smaller heat-racing style hulls
are also running mid-to-upper 50s as well, some pushing into the
low 60s in race trim. I had a personal best speed of 57.4 mph
in race trim, definitely fast enough to win races. With the Avenger
setup a bit more loose, and the hull contacting the water only
on the last few inches of the sponsons, I was able to run 63.2
mph with a 6717x3 propeller. Rpm readings were always within 17,500
to 18,200. The Neurotoxin was definitely running strong. Throttle
response is absolutely instantaneous with no lag getting on the
pipe with my current exhaust configuration and I experience almost
zero drop in rpm when turning.
are a few things to remember when operating a full-mod such as
the Neurotoxin. Oil content is crucial for proper lubrication.
These engines are operating way outside the limits of a stock
Zenoah and must be taken care of accordingly. Mix your gas at
around 8:1 and watch your high-speed needle setting; it shouldn't
be much below 1-turn from closed. Your spark plug is a window
into seeing how your engine is operating. Spend some time with
the veterans at your local club and learn to read a plug. Also,
if you "dunk" your engine after blowing over or smacking
a buoy, make sure to clear the water out of the engine before
you attempt to restart. Doing so will prevent catastrophic damage
to the con-rod. Once you've removed all you can, run the engine
a few laps at a low rpm to burn off any water left behind.
Neurotoxin is one of a few high performance racing engines that
set the pace for the rest of the field. And even though it's a
mill made for racing, it's equally at home in any sport boat big
enough to handle a Zenoah. I've been running this engine for a
few months now and it's held up very well, even with my Avenger
liking to fly more than staying on the water; the engine has been
dunked over 10 times since I started the review and not one problem
has arose. If your in the market for a new engine for your race
boat or sport boat, take a look at TRM's Neurotoxin and I promise
you wont be disappointed.
Distributed exclusively by: Toxic Racing Machines
133 E. 10th St.
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.