OEM BORGO brand piston sets to suit the Fiat SOHC engine found in Fiat 128 Coupe 128 Rally 128 3P and Fiat X19 1300. 86.6mm bore size set of four pistons / rings / gudgeon pins / clips

 

Can also be used as a high compression alternative in 1500 SOHC engines as well.

34.7CH, 0.6mm dome, small valve flycuts. 

standard compression for the european specification of this engine in post 1974 European spec 1300 is 9.2:1

86.6mm is a 0.6mm over size for the SOHC 1290cc engine found in Fiat 128 sport coupe, 128 Rally, 128 3P and X1/9 1300.

86.6mm is a 0.2mm oversize for the SOHC 1495cc engine found in Fiat X1/9 series 2

Full Chromed top ring. Very high quality, Italian made.

Fresh sealed boxes, NOS, have been sitting on a shelf for over 30 years

Buy It Now is for ONE box with a set of 4 pistons fitted with rings and gudgeon pins as in the picture.

Postage worldwide at cost, packaged weight approx 2.70kg

Ignore the listed ebay international postage cost, this is just an estimate, postage varies to different regions around the world. If you want a postage estimate to your country, just ask.

Theoretical static CR in a 1500. 

A basic compression ratio calculation looks like this: 

Volume at BDC is (swept volume + minus deck volume - dome )+ flycut volume + ring land clearance volume + gasket volume + chamber volume.

Volume at TDC is (volume in gasket - pop up - dome) + flycut volume + ring land clearance volume + chamber volume.

Volume of BDC over Volume at TDC is expressed as a ratio to one (xx:1)

Assume bore is 87.00

These Pistons are 86.50 above the top ring land and the top ring groove is 7mm down from the crown.

The Valve Flycut volume is approx 1.0cc

The Piston sits at approx 0.3mm minus deck

The dome is 0.6mm high, 36.5mm in diameter and a "spherical cap" in shape.

The Nominal Combustion Chamber volume is 33cc (non decompression recess head)

Your head gasket is going to be 1.2mm compressed and has an inside fire ring diameter of 87.2mm and will give a SQ clearance of 1.5mm

So let's do some math...

Swept Volume of the cylinder. 

Pi x R squared x Stroke

3.14285 x (43.5 x 43.5) x 63.9

3.14285 x 1892.25 x 63.9

380.017cc

Volume of the piston 'minus deck'

3.14285 x (43.25 x 43.25) x -0.3

3.14285 x 1870.5625 x -0.3

-1.765cc

Volume of the 'spherical cap'.

[3.14285 x (0.6 x 0.6) x (3 x 18.25 - 0.6)] / 3

[3.14285 x 0.36 x 54.15] / 3

0.204cc

Volume of the head gasket.

3.14285 x (43.6 x 43.6) x 1.2

3.14285 x 1900.96 x 1.2

7.17cc

Volume of the ring land clearance.

[3.14285 x (43.5 x 43.5) x 7] - [3.14285 x (43.25 x 43.25) x 7]

[3.14285 x 1892.25 x 7] - [3.14285 x 1870.5625 x 7]

41.63cc - 41.15cc

0.48cc

and then put these numbers into the equation,

Volume at BDC = (380.017 + 1.765 - 0.20) + 1 + 0.48 + 7.17 + 33

= 423.232

Volume at TDC = (7.17 + 1.765 - 0.2) + 1 + 0.48 + 33

= 43.215

V at BDC / V at TDC = 9.8:1 (9.79363)

I have many more high quality and performance parts available for the Fiat SOHC engine. ARP head stud and main stud kits, GMB water pumps, OE Fiat oil pumps, Graf timing and oil pump drive gears, Akron silicone engine seals, Pirelli timing belts, Fitchel and Sachs clutches and much more, just enquire.

For buyers within Australia payment by bank direct deposit is preferred.