VVC - Low compression

[catastrada]

Yesterday I measured the compression of my VVC engine (EU3 / 160bhp).

Beginning from cambelt side:

Cylinder 1: 15 bars

Cylinder 2: 14 bars

Cylinder 3: 13 bars

Cylinder 4 : 16,5 bars

 

I don't know the standard compression for this Engine, but mine seems low and with a quite big difference between the cylinders.

 

 

Now what do I do?

 

I plan to end the "year" (5/6 track days) and then to have it "repared".

For legal reason, I will keep the VVC system.

I think of 3 solutions :

 

- Buy a new VVC Engine: around 3,500 €

 

- Have mine repared with standard parts: I guess 1,500 €

 

- Have mine repared with parts to improve the reliability : forged pistons, solid followers (I'm fed up with the noise of the hydraulic followers), and ??

No idea at all about the cost.

 

What do you think ?

 

Edited by - Catastrada on 19 Jul 2008 08:08:04

[oilyhands]

What conditions was the compression test taken under, fully up to temperature and with the throttle fully open?

 

A 10% variance from the arithmetic mean is acceptable

 

If so then the next step would be a leakdown test to discover what the cylinder leakage percentage is and where it is going.

 

You cannot use solid followers with the VVC mechs since the ramp is desiggned for a hydraulic follower. In my experience the noise is very very rarely the hydraulic followers it is *certain* to be the VVC mechs. Replacement of these with known quieter ones is the only solution.

 

The 160 pistons are tougher than the regular ones and are probably up to the job of surviving the use to which you are putting the engine.

 

In short a little more diagnosis is called for before tearing the engine down, if the leak is in the head then it is a less painful procedure to put it right.

 

Oily

[catastrada]

Thank you Dave for this quick reply.

 

Any idea of the regular compression values ?

[oilyhands]

That would depend on how well calibrated the gauge is, but anywhere around 14-15 bar is good.

 

Oily

[catastrada]

I forgot to have full throttle fully open during 😔 the compression measurement 😔

 

I will redo them.

 

Is there a way to be sure that the valves are closed to test the head except removing the "top of the head"?

[oilyhands]

Get the engine to TDC on the cylinder you are testing with the leakage tester, if the leak is 100%, do a complete engine revolution to the next TDC on that cylinder. Once you have established a single cylinder at TDC with the valves closed you can foloow the firing order of the engine, 1,3,4,2.

 

Oily

[catastrada]

I will follow this 😶‍🌫️

 

Edited by - Catastrada on 20 Jul 2008 08:51:16