Manufacturer C.M.B. Country Italy Type 21 EVO 3 RALLY

* factory supplied numbers

An Italian buggy engine from one of the famous world champion manufacturers of 3.5 cc boat engines.
With the knowledge of these boat engines C.M.B has manufactured nice looking and good performing buggy engines the past few years.
At TWF8 we already tested with good results and durability CMB off road engines.

For the season 2003 CMB has improved their 2003 line a little more.
The new 2003 serie engines called EVO 3 have been undergoing the following changes:

* New materials used
* The conrod has now two bronze bushing
* A new main bearing
* A coating on the conrod pin
* New port timing
* New type II 8 mm flatslide carburator
* The black anodized color of the cranck case

THE BOX
When we received the engine from the German C.M.B distributor ECK -TEC the factory seal was broken. We know him personally so are assured there is nothing wrong with the engine :-)
When you buy an engine be sure that this label is intact. If not, ask the shop owner to check the contents before buying it.

The seal of the the box was already broken as said. The engine is nicely packed in two plastic airtight bags so no debris can enter. One is with bubbles. Further in this case no user guide with instructions to maintain and break-inn the engine.
We can discuss about the fact these engines are only purchased by experienced users. But some distributors seem to forget that these engines might fall into the hands of non experienced users. So break inn and users instructions are a need. If you need info about breaking in CMB engines click here or for general break in click here
Further in the box we have:
*A normal type 6 glowplug
*The black aluminum flatslide carburator type II.

THE ENGINE
The new cranck case is black anodized to reduce the engine temperature even more then compared to the previous models. Still it has the two extra ribs at the bottom of the cranck case. At the back of the engine where the cover plate is placed the engine is not 100% manufactured, now better visible due to black color. It might that it has no influence on the performance but it is not looking nice.

Also a full ABC piston-liner is used in this race engine. The patented system of the tapered piston design makes it different from all other known buggy engines. The piston is a so called "intelligent piston". 

CMB has a patented system to manufacture the piston called "intelligent piston" in such a manner that the thermal specifications make it less critical for break-in and expands the lifetime of the piston/sleeve.
Break-in is reduced to a period of around 4 tanks of fuel running the car in rich setting on the track.

When the engine is just started it might sound a little crunchy. But when it is warm (take the time a few laps will do fine) it will sound OK. Also when finished running, let the engine idle stationary for 30 seconds and then cut the engine. Place the piston in its lowest position. This will make starting an other time easier.

Also a cut out (ditch) in the top of the piston is there to provide better performance of burning the fuel.

More features are the  C.M.B Multi Exhaust System "MES" incorporated in the sleeve. The system speeds up the gasses leaving the exhaust and fills it with fresh fuel mixture. Beside the 5 ports in the liner there are two extra ports in the piston. They are working together with the "MES" ports to provide more power and better fuel economy.

The conrod in the new version has now double bronze bushings.

The engine is a long stroke one and the cranckshaft measures 13 m/m. It has three carved TURBO cutouts at the end near the cranck pin (bigend). This is to better the fuel flow to the combustion chamber.

A new style green cooling head makes it looks nice and also efficient for the right amount of cooling without making it too heavy. The cooling head is constructed with a head insert that accepts only normal glowplugs.

THE CARBURATOR
The new version of the flat barrel slide carburator is nicely black colored (anodized) and is made out of casted aluminum and then machined with a CNC machine. This TYPE II version of the flatslide is still a story of its own that needs however some rework we will show later. There were already flat barrel slide carburators made by Picco for car engines but they were made out of composite plastic. As producing and maintaining the right specification over a period of time the composite material could give problems in settings and reliability. Instead of plastic this carburator is completely manufactured with a CNC machine out of aluminum. This means that the tolerance of the carburator will stay the same. Around the throat of the carburetor that goes into the crankcase there is no nylon isolation bushing as it was with the previous models. This nylon thermal isolation bushing is to prevent the full metal carburator getting hot by transporting directly the heat from the crankcase to the carburator and causing "vapor lock" in the fuel system. So it is likely to be this engine will have in hot condition the VAPOR LOCK problem.
Manufacturing this carburator is a still a costly process, but it looks very nice and stable.
Three needles in total for adjusting high speed, bottom speed and idle speed at one side of the carburator. The angle of the idle needle is horizontal and can easily be accessed from the left side of the car. No hussle with muffler.
The airflow of the intake and the part that fits into the crankcase is nicely tapered to give better airflow and so performance of the engine.
The carburator is a fixed 8 mm version and does not accept other diameter airflow inserts.
The flatslide carburator will give extra bottom power. 
If you like to smooth out the bottom power on slippery tracks use a round barrel slide carburator like the Nova Rossi based ones.

The carburator is large. Then I mean within all areas. Fitting this one in for example a MUGEN MBX-4 needs rework over the throttle linkage. The total width differs 12 m/m compared with a Nova Rossi based 8 m/m carburator. Also due to the larger height the airfilter is touching the inside of the body more. This all shouldn't be a big problem. But when you are used to swap Nova based engines (training/competition engine) this could provide a little more work. BTW a Nova Rossi 15 m/m throat diameter based carburator fits with and extra O-ring on it. The throat is a 1.5 m/m longer and will not fit airtight against the crankcase if the extra o-ring is not placed. Compared to the previous flatslide the throttle connection ball that moves the flat slide barrel is now fixed and is not rotating anymore, good point.

A rubber shielded NMB bearing is sealing the front. A large main bearing does its job inside.

The first impression of this engine out of the box is OK. 
Parts and engine are nicely machined and assembled except for the rear part of the crankcase!
It would be nice an user manual is supplied
The specs tell us it is a bottom power engine.
Together with the flatslide this will only be more.
No horsepower or torque rating available.
The real engine performance and fuel economy can not be judged by looking at it. So we will track test this engine and compare it with others and if possible dyno test it.

TWF8 rating **** stars
five stars is maximum

Paco Raap 28-08-2003

THE ENGINE
	The box with the engine with a broken seal. The label on the box says "Rallye LSi
	The contents of the box
	All the parts of the engine
	The exhaust port with the two M.E.S booster ports and channels
	One of the booster ports and channel clearly visible
	The large inlet port at the front
	The other side with the second extra booster port and channel
	The nice chromed layer inside the bronze sleeve is lapped and rectified
	The crankcase inlet for the carburator does not have an internal O-ring near the bottom like Nova Rossi based engines have.
	The new type cooling head
	with a larger top diameter as the previous 2001-2002 specs engine
	The normal type 6 glowplug that comes with the engine
	The head insert viewed from the top
	The combustion chamber in the plug head
	A single 0.1 aluminum head washer fits between the plug head insert and the sleeve.
	The engine rear cover is the standard one and in this case blacked anodized It has one sealing O-ring. The 2 hole rear cover can be fitted as option.
	The bronze cone for fitting the flywheel
	The 13 mm crankshaft with the wristpin (bigend) with the coating.
	The two turbo slots in the cranck shaft to provide better fuelflow of the engine.
	The crankshaft with SG thread
	The piston with a little ditch in the top also has two extra ports in the piston itself. These ports correspond with the M.E.S booster ports in the sleeve. The new conrod now has double bronze bushings with an oil hole in the lowest one at the outside.
	The spot where you can remove the piston pin has an small dropcurve so you can easily remove the piston pin retainer G-clip. The piston has a small oil groove.
	The right side of the engine
	The left side of the engine
	The rear side of the engine
	The front side of the engine
	The engine with the carburator fitted seen from the right side
	The engine with the carburator fitted seen from the left side
	The engine with the carburator fitted seen from the rear side
	The engine with the carburator fitted seen from the front side
	The engine with the carburator fitted seen from a right top angle
	The engine with the carburator fitted seen from a left top angle
	Comment will follow!
Comment by ECK-TEC
THE FS II CARBURATOR
	The new type II 2 needle full aluminum flatslide carburator
	The new type II 2 needle full aluminum flatslide carburator
	The new type II 2 needle full aluminum flatslide carburator
	The new type II 2 needle full aluminum flatslide carburator. The connection ball on the slide is now a non rotating one
	The new type II 2 needle full aluminum flatslide carburator with a flowed fixed size air intake of 8 mm
	The new type II 2 needle full aluminum flatslide carburator with a flowed fixed size air intake of 8 mm
	The shafts that holds the carburator to the cranck case with the black plastic busing and the bronze nut.
	After the modification of a little 0.8 mm hole drilled in the flat slide the carburator was working OK. This carburator is very critical and sensitive on the settings you make. A 1/8 of a turn can make the difference where other carburators needed 1/54 of a turn. So we advise this carburator not for novice drivers who have low or no knowledge of carburator settings. For more information about correct setting up CMB flatslide carburators look here.! Just as the R4 this carburator is full aluminium without insulation we have to see if this is not causing vapor-locks in hot conditions!
Comment by ECK-TEC	The problem with the critical adjustments of FS II was known to us and we therefor asked CMB to design a new carburatorallo which is now the 04 R. A insulation bushing is not needed for this engine.
THE 04 R CARBURATOR
	From 2004 season all CMB engines provided by ECK-TEC will be equipped with this new full aluminium 04 R style 3 needle round barrel carburator. The carburator looks to be a copy of the known Nova Rossi style carburator but then in full aluminium.
	Here the comparising between the FS II and the 04 R where the 04 R is a little smaller over the FS II. Also this cabrurator has a fixed 8 mm size intake that can not be changed.
	The new 04 R type full aluminium 3 needle carburator.
	The new 04 R type full aluminium 3 needle carburator with description of the needles.
	The bronze colored third needle for setting the medium speed needle. Take care with turning this screw as it works in conjuction with the low speed needle
	The low speed needle that works in conjuction with the medium speed needle.
	The new 04 R type full aluminium 3 needle carburator.
	Just as the FS II this carburator is full aluminium without insulation we have to see if this is not causing vapor-locks in hot conditions!
Comment by ECK-TEC	The problem with the critical adjustments of FS II was known to us and we therefor asked CMB to design a new carburatorallo which is now the 04 R. A insulation bushing is not needed for this engine.
THE MUFFLER
	The 9904 muffler that according to the label on the box is to be used for ONROAD.
	The parts from the box: 9904 muffler, silicone connector and set screw
	The muffler has a mounting connector placed on top of the muffler instead on the front. As most cars use a front mounting connector and all parts are designed for that a front connector would have been nice.
	The entry of the muffler has a groove so a ty-wrap will have better grip
	We do not know why CMB is mounting these connectors at the top of the mufflers A front connector would have been more standard and needs less modification for all cars!
Comment by ECK-TEC	CMB has made a new muffler with the code name EFRA 7203 that now has again a normal front connector.
THE HEADER
	The header that came with this engine exist of:  The header, a silicone adapter to fit the exhaust port and a large single spring. A very forward swepped header can cause some mounting problems.
	A practical example is the case of the Mugen Seiki MBX-5 where the 9904 muffler is sitting very far to the front with the original header used. In case of the muffler mounting connector placed in the front of the muffler it would have been impossible to mount it anyway. So if you feel this mounting is not to your standards use a header with less for ward swepping! In this picture the engine is shown with an optional King Headz cooling head!
	The header in combination with the 9904 muffler can give some mounting problems we think are not needed. Why does CMB uses forward swepped headers?
Comment by ECK-TEC	The header that came with the engine is to long and need to be cut down to the appropiate size. Whit this old style header you need to cut it so 8 mm is left. Curve the edge with a small plyer and smooth the edges with sandpaper so a Zipty will not come off.
THE POWERPLANT
	When all parts put together then this is the right view of the power plant
	When all parts put together then this is the left view of the power plant

If you mount the engine on the engine mounting blocks be sure that the bottom surface of the engine mounting blocks is flat. The engine mountings blocks of the Mugen (MBX serie) and Kyosho will have no problem. How ever the engine mountings blocks from Thunder Tiger are not straight at the inside and they conflict with the two extra ribs that are on the bottom of the crankcase, so flat mounting is not possible. Therefor remove some material (the marked triangle) at the marked spot of the engine mounting blocks. If the engine is mounted check if the ribs are not touching the inside of the mounting blocks anymore.

Performance

We sign 21-09-2003
Used a heat gun to warm up the engine
After a two tank break in with the supplied FS II carburator we changed this one to the known R&B 8 mm.
With the FS II carburator the settings were very critical and not easy to find and that is what we not like to happen with break in
With a heat gun brought to temp on the starterbox we heat cycled it two times and after those two times we put the engine on the track.
It had 6 tanks of fuel before we really adjusted it between the heats and the final to 90% of the real race setting.

During the break in the engine stopped due to the rich setting a few times. 
But during the finals racing it ran perfect with a race temp of 109 degrees Celsius on the plug measured.
I not gonna state if it is a screamer or bottom power engine.
This can only be done on a properly working dyno we are still waiting for.
It provides enough power at the moment and after just 1,5 liter of fuel it is not showing its full potential yet.
For the moment we are happy with the engine.
Next race we will mount the FS II carburator with the modification as described on the CMB USA page.
We already drilled a 0.8 mm hole in the slide of the carburator which will improve lower to middle engine pick up setting.
If that does not work we can always switch back to a FS I series carburator or the R&B 8 mm composite carburator.

Testimonial:
Test track Purmerend, The Netherlands
Outside temperature 18 degrees Celsius
Kyosho MP-7.5
3 pin clutch, black shoes with 2,6 mm hole, 1.1 mm springs
Plug Rossi 6
Fuel Model Technics Dynaglo 16% Nitro
Pipe R&B 063
Carburator R&B 8 mm composite

Paco Raap

We write 05-10-2003
Again a new race for the Dutch Brother Cup 2003.
I had mounted the FS II carburator and the recommended CMB 9904 exhaust.
Before the race I had some time to adjust the carburator. Although I found the correct settings very soon the way to achieve that was by just turning in 1/16 step turns! This makes setting a little critical for novice drivers. When you are used to turn in 1/8 to 1/4 steps you might overshoot the right setting quickly.
Engine ran an average 110 degrees Celsius at the plug the whole day.
The idling was a little inconsistent. When the engine was cold and started it was to low. When it was at temperature it was a little to high but not interfering!
I have to check next time when practicing if we can change the setting on the carb to reduce this effect.
The new CMB ROUND BARREL slide carburator was not in on time for testing. We will wait for this from ECK-TEC as it comes in and test too.

As my father also drove with me the same car the engine was used for more then 2.5 liters this day.
Engine never flamed, had enough power (a little more at the bottom compared to the 8 mm R&B carburator) till the end of each heat and final.
I drove steadily in the A-final and won the race.

Testimonial:
Test track Purmerend, The Netherlands
Outside temperature 13 degrees Celsius
Kyosho MP-7.5
3 pin clutch, black shoes with 2,6 mm hole, 1.1 mm springs
Plug Rossi 6
Fuel Model Technics Dynaglo 16% Nitro
Pipe CMB 9904
Carburator CMB FS II

Paco Raap

We write 14-12-2003
We are currently having season break and are not able to test the engine furhter.
As soon as 2004 seaon starts we will update with more info and will also test the R 4 carburator .

Temporary conclusion:
Sofar the engine performs like it should but the FS II carburator is not suitted for novice drivers although it adds a tad of bottom power to the engine.

Paco Raap

21-03-2004

Testimonial:
Test track Purmerend, The Netherlands
Outside temperature 8 degrees Celsius
Protech Enigma
Speed II clutch black shoes 0.85 mm springs
Plug R&B 6
Odonnell RACE 20% Nitro
Pipe Protech Enigma
Carburator CMB R4

We mounted the 04 R round barrel carburator and headed to the track.
With only some minor adjustments for the Low and High speed needle we got it fairly quick on race tune.
Some other CMB drivers complained about the fuel leaking from the boot around the carburator barrel.
We discovered some fuel too but where not concerned about it as it was not much.
I used a zip ty to secure it to the carburator and found after 45 minutes of driving no fuel anymore.
The engine still perform wells and the 04 R carb makes the engine more linear compared to the FSII flatslide carburator.
Sofar the engine ran 4 liters of fuel with no problem.

Paco Raap

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