compression, does this sound right?

[2003z]

Using the stock L-28 sizes in the engine calculator, (F54/P90/Flat tops) gives a 44.6cc combustion chamber and 9.82 CR.

 

I will be using these domed pistons, but there is no volume info on them to be found anywhere. The dome is according to my feeler gauges and calipers, .686 mm tall and 58 mm across.

 

I calculated the area of the dome 22/7*29*29 and come up with 2643 sq cm, then multiply that by the height .686 and get 1813 cubic mm. or 1.81 cc.

 

Then I went into the engine calc and subtracted 1.81 from the combustion chamber size, as that seemed to be the easiest, which gives me a 42.8cc chamber and 10.14 CR.

 

Does that sound like logical calculations?

 

[2003z]

Also, is there a way the piston should be oriented in the engine relative to the valves?

[gjc5500]

not sure but i think it is the dished area to the valves

[73ZCAR]

2003z,

 

I belive the notch goes toward the front,which will probably put your dome in the area where your valves are.If this is the case you will need to add valve reliefs to the domes.

 

Mike.

[2003z]

2003z,

 

I belive the notch goes toward the front,which will probably put your dome in the area where your valves are.If this is the case you will need to add valve reliefs to the domes.

 

Mike.

Actually, if the notch is towards the front, the dome will be on the oil filter side of the engine. I wouldn't think you would have to relieve stock nissan pistons would you?

[2003z]

so did I calculate the CR correctly?

[73ZCAR]

Those aren't stock pistons.

 

You may be able to use them with a p79 or p90 head without valve reliefs.

 

I think they were designed to be used with these heads to slightly raise compression.

 

With any other head you may have problems.

 

Yes the math looks ok to me.

 

Mike.