CEN Racing's Matrix RTR is a 1/8 scale nitro buggy. The basic specifications for these types of buggies are nearly unchanged for some decades now. This also applies to the Matrix as it features a 4WD drivetrain with three oil-filled gear differentials, front and rear brakes as well as an independent suspension with four oil-filled shock absorbers. To this adds a two stroke nitro engine with .21 cubic inch (3.5 cc for us metric guys) displacement. So far, so simple.
Overview
The CEN Matrix in particular bases on a nearly 3 mm thick hardcoated aluminium chassis plate. The chassis plate shows a kick-up on the front that sets the front wishbones to a slight angle for better straight line stability and also prevents the front from catching with the track surface on landings and during taking off from a jump.
To give the chassis all the stiffness it needs for the rigors of off-road bashing and racing two aluminium braces swing from the front and rear gearbox towards the chassis plate. This again is a feature we can see on nearly all 1/8 scale buggies with the difference that some feature plastic parts instead of alloy items. Also made out of aluminium are the steering brace the front end top plate and the radio plate that houses the steering and throttle/brake servo. The supplied servos offer 10 kg of torque, dual ball bearings and metal gears according to the sticker on top of them. The radio plate is screwed down on aluminium stand offs which is a nice touch as sometimes cheaper plastic stand offs come into play on 'cheap' ready-to-run buggies.
Next to the throttle/brake servo the center differential and brake assembly with a total of four vented brake discs is located. The design of the brake linkages allows for an independent adjustment of the front and rear brake bias if needed by turning one of the two knurled thumb screws.
A plastic box for the receiver and receiver battery box locates just behind the radio tray. The box offers more than enough space for the tiny Sanwa RX-361 40MHz FM receiver and the four cell battery holder.
The suspension consists of some of the bulkiest parts we have ever seen so far on an 1/8 scale buggy. Both the wishbones and the wheel hubs look very strong and seem nearly indestructible. The upper camber rods consist of large plastic ball cups and very thick metal turnbuckles with left/right thread for easy adjustment with a small screw driver. The suspension also features front and rear swaybars for controlled chassis roll in corners. This is a feature often seen on competition buggies and it's a nice touch to see them on a recreational buggy like the CEN Matrix too.
The shocks used on the Matrix are all-aluminum types with lower shocks boots, medium hardness springs and feature plastic clips for easy ride height adjustment. The upper spring retainers feature small 'wings' on which you can pull the retainers down to clip on the ride height spacers. That's pretty trick as, especially when things start to become a little dirty conventional retainers are hard to grip. Thumbs up for that idea.
Let's come back to the drive train for a second or two. The power delivery from the central differential to the gearboxes happens via two strong looking universal drive shafts with a design often seen on competition buggies. The same style universals are found on the front and rear drivetrain with the so called Constant Velocity drives making for an efficient drivetrain and less maintenance needed. What we liked about the universals is their 'captures pivot pin' design. The wheel axle and the coupling pin of axle and driveshaft is captured by the large inner bearing doing away with lost pivot pins that other designs are prone for.
Track Test
Going to the track test we only have one suggestion: preparation. Followed by preparation and preparation. You can never be over-prepped! What we try to say is: charger the transmitter batteries, charger the receiver batteries or battery pack, charger the igniter battery. Nothing is more frustrating than sitting on the track being not able to start the engine because of a discharged igniter battery!
Having charged the battery packs? Ok, then move on. The air filter of the Matrix was pre-oiled which is a plus as sometimes this is something you can easily oversee with the result of a ruined engine.
Have you ever started a brand new nitro engine? If not, just take a minute and read our 'How-To (start a brand new nitro engine) feature here. After prepping the engine it came to like on the first pull of the recoil starter. That's what we call a really beginner-friendly engine! We let it idle for around a tank and restarted it after it was left for a cool down. With the second tank we noticed that the .28 big block was a bit on the rich side so the fuel mixed was leaned on the carburetor by screwing the low speed needle half a turn in. Additionally the idle was raised slightly to make for a nice and only slightly raised idle RPM. We left the Matrix alone for another tank of fuel.
For the third tank it was time to move the Matrix for the first time on the track. We used the same semi-permanent hard-packed, soft dirt track as we did for the review of Tekins T8/RX8 brushless motor/speedo. The carburetor setting still was on the very rich side so we leaned the mixture on the main needle half a turn with the result of a very constant idle and decent transition from low to high RPMs. With this setting we drove the next couple of tanks. For three more tanks we only use around half way on the throttle to make sure the engines was not stressed to much and monitored an engine head temperature of just above 100° Celsius - just about perfect. With every following run we raised the speed until we felt that the engine felt 'free' enough' to also lean the low-speed needle. Until this moment the engine had problems to properly go to idle as it was too rich. The big block engine hold RPM for around a second or two with a closed carburetor which indicates a too rich low-speed needle. Therefore we screwed the needle in question half a turn in and now the engine showed its full potential: a very constant idle, responsive going on and off the throttle and a massive top speed. The engine seems to work best at around 115° Celsius around the glow plug so try to adjust this temperature with the main needle if possible.
On the track CEN's Matrix RTR behaved very good. The kit tyres gave good traction on both the hard and soft parts of the track and with a slightly raised rear end the buggy was virtually glued to the ground on the rough parts of the track. Only the servos are not to out liking! They seem to be powerful enough to do the task but especially the steering servo is much too slow. Full steering throw from left to right (or right to left) takes forever and therefore the steering reaction of the buggy on the track is not agile enough. Especially beginners profit from an agile car as slow steering reactions make many RC-Car drivers feel uncomfortable.
Beside the slow transit time of the servos CEN's Matrix RTR buggy behaved like a beginner buggy should be. Despite some horrible landings or contacts with track markers nothing broke or bend. The chassis and suspension components proofed to be rock-solid and the powerful engine was a real joy. With one exception. Like many nitro engines CEN Racings .28 unit tend to become hard to restart in hot condition. Probably the carburetor isn't isolated that well and the hot crank case of the engine heats the carb up too much leading in bad 'hot starting' characteristics. To overcome this just let it cool down for five minutes. After that short period the engine fires up on the first pull of the recoil starter!
In Detail
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Transmitter and manual CEN's Matrix comes with a MX-3 Sport called three-channel transmitter that offers 10 model memory, an LC display, steering and throttle trim, end-point adjustment as well as dual-rate for the steering servo. This means you can easily use the transmitter for a second or third (or up to nine other cars) given you have so many receivers. The MX-3 is a really nice transmitter for an RTR buggy and adds to the good impression we have of the Matrix buggy. The manual is very comprehensive although not very good looking. It offers an assortment of different flyers for parts ordering, running the engine in as well as a manual although this is not needed for an RTR buggy. But, to be frank, having a manual helps a lot when wrenching on the buggy like replacing parts etc. What we really liked was the fact that CEN supplied good information about how to tread the engine as this is something that is often overlooked by the companies. |
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Front end On the front end we find bulky 16.6 mm oil-filled shocks with medium hardness springs, and 3.5 mm shock shafts covered by rubber boots to save them from becoming dirty during off-road bashing. The front shock tower is made out of 3 mm alloy and features the same colour as the chassis. Different mounting positions for the shocks are available at the shock tower and the wishbone allowing for complex suspension set-ups if needed. |
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Air filter The Matrix comes with a pre-oiled air filter which is a good thing but our example was a bit squashed by the body. As the lower opening, the part that attaches to the carburettor, sits off-set in the air filter body we simple turned it 180 degrees to make the actual filter sit closer to the center of the chassis away from the body. |
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Fuel filter Like the air for the carburettor the fuel is filtered to avoid debris and dust from entering the engine. The filter is quite tiny but contains an inner sinter filter element something not often found on RTR models. Again a very nice touch from CEN. The four brake disks are made out of steel and feature ventilation holes to make for consistent stopping power even when using the brakes often. |
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Receiverbox The receiver box housed the small receiver and the four-cell battery holder. This should be thrown out as soon as possible and replaced by a four or five cell receiver batter pack. These offer additional safety due to soldered cells. The connector used is a so called 'BEC' connector so make sure to buy a pack with one of these red BEC plugs as the 'universal' or 'JR' connectors wouldn't fit! |
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Technical data CEN Matrix RTR - Length: 485 mm - Width: 305 mm - Wheelbase: 330-336 mm - Weight: 3350 g |
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Likes & Dislikes + Strong and reliable engine + Rigid chassis and suspension parts + High specifications - Minor tweaks needed like body clearance and foam for the receiver box - Slow servos make in slow reaction of the buggy |
Links:
For more information please visit CEN Racing
