pistons

[cheaterparts]

some pistons that scott the Ebay junky ( superscan811 ) has picked up for his short stroke astron they are WISECO forges
and the weight with pin is about the same as a std 2.6 piston ( measured on the cooking scales while the wife was out today )

the top is sitting with a holden 202 piston and the bottom beside an old 2Lt piston that I had in an early build with the block decked a bit

it looks like a 2.6 block decked about 0.030" with these pistons and preped std rods on a 2Lt crank will net about 11.5 : 1 with a std M6 head
or that is the plan

so atm the build spec will be
pistons as above - preped std rods ( polished/peaned etc ) - 2 lt knife edge crank with scaper - the head M6/7 with 48 mm titanium inlet and 40 mm titanium ex ported - cam -
quad TBs
I will try do the build with a camera and post it in the build section
anyway the block that we are using will be apart this w/e to be cleaned and bored

[Superscan811]

Cheater, I think i muffed up the earlier calculations (was working on the 2.6L stroke not the 2L)

M6 or M7 head ( 70cc )
2.6L Block
2L Crank ( 90mm stroke )
Std rods
Celica piston ( 92.5mm Dia, +24.7cc dome and 38.9mm Comp height )
The standard 2.6L piston with a Comp Height of 35.5 sits .6mm below the deck

The top of the piston (Comp Height not Top of the Dome) would sit 1mm down the bore and the CR would be 11.05

Deck the block 1mm ( the piston is level with the top of the block ) and you have a CR of 12.32

Deck the block 1.3mm ( the piston is proud of the block .3mm ) and you get a CR of 12.76

Hope I got it right this time.

Cheers.

[Billsy]

with that much dome, are they going to go clear with large cams and piston clearance?
do they have cutouts in them?

[Superscan811]

with that much dome, are they going to go clear with large cams and piston clearance?
do they have cutouts in them?

Cheater was running those other pistons with a bucket load taken off the block and head (guessing somewhere between 4mm to 5mm).

With these pistons, using standard rods, standard 2L crank and standard 70cc M6 or M7 head, you will have a CR of 11.05:1 and NO problem with valve clearances.

But like any modification to the valves or cam, you need to check the clearances.

Working it out on paper is one thing but you always need to CONFIRM it is correct.
Just check out what happened to my old cam because I didn't check for spring bind.

With the CR, Valves and Cam I'll be running, it would be very surprising if I (well Cheater) won't have to make a few fly-cuts to allow the valves to move un-hindered.

The average person, for around $1500, (Forged pistons $750, M6 or M7 head $100, 2L crank $100, bore and deck the block $200, Gasget kit $100, Cam $250) and a reasonable bit of personal effort, you can have a strong N/A engine that flows well and has a good Compression Ratio for more power.

Cheers.