Bore Over Size Comp Ratio Volume CCs Head CCs
83.50mm +0.5mm 8.6:1 -4cc 50
Height Stroke Rod Length Pin Diam Weight
1.201"(30.5mm) 3.346" 5.228" 20mm 293g
Ring P/N Note
I have a set of factory sealed pistons for a turbo build on a 1.8l
Open the box and this is what I see, pistons still sealed in there bag with wrist pins.
I see a nice label on each piston with the pertinent info.
Part Number checks with what is on the box.
Proper bore size listed.
Piston weight listed at 278g
On all 4 pistons, We will see.
On the Supertech website,
They are listed to have a weight of 293g
15g difference between posted info and what is in the box.
Now to get them out of the packaging and give each a quick look over for any shipping damage.
Top looks good
So do the bottoms and the ring lands.
Now to weigh each one.
This piston was jumping between 279.0g and 279.1g
This one bounced between 279.4g-279.5g
So piston #3 is the lightest at this point.
Next is to weigh the wrist pins.
As you saw in the above pic, the wrist pin was packaged with the piston.
Wrist pin #1
Wrist pin #3
Wrist pin #4
Sorry, no pic
The weight difference is rather wide for wrist pins.
Now , to weigh the combo and get the combined weight of the piston and wrist pin.
So we have a range of weight from 376.6g lightest to 378.8g heaviest.
The average weight is now 377.5g
Now since the wrist pins have such a variance of weight, I will swap them around some and see if I can get them closer.
Piston #1 with wrist pin #2
Piston #2 with wrist pin #1
Piston #3 with wrist pin #4
Piston #4 with wrist pin #3
No pic, Sorry
Well, now this is a whole lot better, Now the weight difference from lightest to heaviest is .5g
Now to check the wrist pin clips and see how close they are.
10 for 10 C clips weigh .8g each.
They can be hung on the rods at this point, But I want them closer.
My lightest now is 377.4g
With a touch on a belt sander, on the lip by the wrist pin boss, I will remove some weight.
I buffed on 3 pistons to get a matched weight of 377.4g
Piston #2 needed .1g removed
Piston #3 needed .4g removed
Piston #4 needed the most removed with .5g
So you have an idea how much a gram weighs, Hold a dollar bill in your hand, That is 1g
A nickel weighs 5g
My over all opinion of the pistons is not too bad, the fit and fish looks good to the naked eye, but the out the box weights need to be checked.
As far as the website posted weight of 293g being off by appox 15g
The label weight of 278g being off by appox 1g
Supertech needs to update its website.
The label weight is close enough to work with.