Thread: Discussion - N1 Piston CR

As above.

My thoughts have been making me do a lot of calculations. I am concerned some of the figures thrown around for n1 pistons are wrong - in regards to their compression they create in a 2.0 VE engine.


Heres my maths and rational.


Stock N1 Engine specs.

86 x 68.7 - Bore X stroke.
11.56 CR
87mm head gasket - 1.2mm thickness.

We all know the N1 head is shaved (apparently 1mm). Also assuming deck height of 0.4mm. When calculating this must be -0.4mm.


Now to get 11.6/11.5 CR we will assume chamber volume is close to 42cc. We are now left with a rought piston dome CC volume of 8cc.

This equates to 11.3:1 CR.

If we substitute with 6.8cc piston dome = 10.9CR
If we substitute with 6.8cc piston dome and 40cc chamber volume = 11.5CR

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Now throwing the above specs into a 2.0 regular VE engine with STOCK head.

86x86
87mm 1.2mm gasket
44cc chamber volume
Pistone dome CC = 8
deck height -0.4mm

CR now equals 13.2

How is this possible? Im simply substituting values.

If we use 6.8 CC piston dome = 12.9
If we use 6.8cc piston dome and 41.8cc chamber volume =13.5



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Calcs assuming VET gasket is used in 2.0 regular VE engine with STOCK head.

86 x86
86.5mm 1.6mm
44cc chamber volume
8cc piston dome volume.
deck height -0.4mm

Calculated CR: 12.6:1

If we use 6.8 CC piston dome = 12.29
If we use 6.8cc piston dome and 41.8cc chamber volume = 12.8


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Does anyone have any idea or thorughts to add? Im trying to get my head aroud what is what and what is and isnt correct. I know the N1 has deeper notches, so maybe my Piston CC is wrong? If my piston CC is wrong, and is in fact lower - it means factory N1 cylinder head has to have a higher CC chamber volume.

Remember im trying to work off the original N1 info - so it all has to correspond and substitute.

other supporting info -
VET metal gasket is 86.5mm diametre.
Stock Graphite gasket is 87mm diametre.
None of these include piston clearance inside the bore. This is the sapce from the crown to the bore, and depth of the first compression ring.

n1 pistons should yield over 13.1 in a 20ve. the stroke and slightly different head on the n1 cause them to be some where in the 11.6-11.9 comp depending on your source.

No one else has any feedback or ideas?

Its all a guessing game if you are based on Nissan stock figures. If you get a chance measure the N1 pistons dome in cc and a real SR20VE head combustion chamber, then you can calculate with real figures. Or better yet, get an assembled VE 2.0 engine with N1 Pistons and fill it with fluid to calculate the CCs. Seems about the only right way.

I've read "guessed" VE chamber volumes anywhere between 41 to 44cc as you state, so which one is correct? This makes a difference

DE head is supposed to be around 47.1cc chamber. Take flat top pistons and calculate CR. Does it come equal to Nissan stated 10:1?

Nissan figures are approximate and should not be used to "extrapolate" other combinations / CRs, its not going to be accurate

Why is it so important to know the static compression? Once you add cams and dial them the dynamic compression is what you want you wanna look at. There are lots of 20ve's with 16ve and n1 pistons, and although the cr is high, it's completely managable even on pump gas.

That said I agree on the fluid method to put this to rest, but then again, are all 20ve heads the same?

No they are not. These are 10 year+ engines we're talking about, so static compression, if it matters, needs to be taken for your specific engine by measuring, not calculating.

True, but the N1 wa sa limited production setup.

232 vehicles made - unknow amounts of spares. The N1 was made for homologation - so it had to be spot on.


Sure dynamic compression will be different. Working off initial static compression is the first base to how things are to be done.

Maybe im just to anal?

just measure yours. no calculations before measurements.