Murena 2.2 Engine Development

[Murena1400]

Finally I have found the time to start a topic about the project I have been working on for quite some time, a better engine for my 2.2S.

The objective; 90hp per liter, which is going to be a bit of a challenge, quite some work has been done and will have to be done to get to this number.

I have first started identifying possible improvements to the engine block and rotating assembly, wich have resulted in the following points that have to be addressed:

- The rods are heavy and out of balance, there is quite some difference in weight between the 4 rods.
- The crankshaft is out of balance.
- Oil return path is not very fluid, a lot of obstacles in the way.
- Oil feed to the oil filter housing has a nasty 90 degree corner it has to go through.
- The flywheel is too heavy and not very well balanced.
- Engine block is not stiff enough in the area of the main bearing caps.

First I have started addressing the oil issues, which a die grinder fixed (visible in the attached photos).
I then proceeded to clean up and balance the rods and crankshaft.

In the next installment I will start working on other things on the block that will have to be addressed.

[Murena1400]

As the block is still in the machine shop for boring and initial skimming I have put some time in determining the camshaft for this engine.

The powerband of this engine is determined to be between 2500 - 7000 rpm, as the bottom end will not be able to sustain anything higher than that, this means that we can stay below 290 degrees of duration, any more than 290 would be pointless.

Scanning through the profiles I had available to me the JRD Number 1, which was originally designed for Sports 2000. Is a very suitable camshaft. 285 degrees of duration, a tighter LCA at 106 degrees and 66 degrees of overlap will make for a very broad powerband, lift is at 7mm on the camshaft.

Ideal lift is calculated to be between 20% and 25% of the diameter of the valve, as the valve lift of the JRD camshaft is 9.6mm, and the size of the intake valve is 47mm, the end result is a minimum amount of lift required of 9.4mm.

Enlarging the intake valve to 47mm means that the exhaust valve will have to be enlarged as well to stay at a healthy ratio, 85% of the intake results in a 40mm exhaust valve.

The camshaft has been ground out of a new original one and is ready for assembly.

[Anders Dinsen]

Thanks for sharing these pictures and reflections, Youri! It's amazing to see documented what can be done to these engines without transplanting turbos or whole new drivetrains on the car. The little things make all the difference. You know I love to see what you are doing. Thanks for sharing to a somewhat wider audience.

Seeing your bottom end work reminds me I have a block in the back of my garage which deserves some attention some day in the future

I know you will be increasing compression on this engine. I wonder if you could elaborate on the advantages and risk of doing so, and what you will do to avoid detonation and overload of the bottom end?