We are just having a batch of 81mm dia forged pistons made to suit 2.0 litre engines.
These pistons have been designed to suit early engines and will be used in FIA Appendix K Period F cars.
I hope to have them in around 3-4 weeks
We are just having a batch of 81mm dia forged pistons made to suit 2.0 litre engines.
These pistons have been designed to suit early engines and will be used in FIA Appendix K Period F cars.
I hope to have them in around 3-4 weeks
Last edited by chris_seven; 02-28-2011 at 11:03 AM.
Chris:
Since you taught us so well, whats the alloy and whats the weight. Are you going to use the more modern X box design?
You should be a crappier teacher!
t
Chris, any chance you will be offering Nikasil cylinders too?
Richard
I agree I should have been more complete with the information.Originally Posted by 912-2.8
I haven't had the weight figures yet but will check and report back.
The Alloy I have ordered is 4032-T6 with Moly Coated Skirts. I could get them in 2618 if preferred.
They are not a Cross-Bridge due to cost constraints.
I had wanted to make a 2-ring very light slipper with a much reduced skirt arrangement involving a shorter pin which would be further up the piston and a cross bridge.
This would have involved making a slightly longer rod.
I discussed this with the FIA Scrutineer who will inspect the engine during final assembly and apply a seal - this prevents it from being stripped at the track - and he said that he wouldn't sign off on these.
The guy who designed the piston has a Ph.D in combustion chamber design and he has recently made a 2-ring piston for a Manx Norton. They also modified the head to include a squish band and designed the piston accordingly.
They gained 7 BHP!!!! (500cc single) The pistons are $300 each and I just wish I could a)afford to do this and b) could run it in an FIA engine.
No, I think Henry at Supertec has a '906' Nikasil barrel that should be OK.
Failing that LN look very good.
I have spoken with Sulzer Metco about making a batch of Plasma Spray Coated barrels but would need a minimum order of 50 units and this is just out of reach financially
Last edited by chris_seven; 02-28-2011 at 10:47 PM.
Chris, very nice, you've been wanting to do this for a long time, I know.
From my old thread on my JE pistons: "Mass is 374 grams. 901/02 Mahle "S"= 364 +/- 3g. Up to '68, the 901/05 weight was the same as the "S." From 1968 on, Type 2000 (901/01, 05, 06) pressure-cast pistons are 371 +/- 3g."
I will be interested to see what the mass of your design comes in at.
It appears that the valve reliefs are 51.7mm and 39.1mm approximately. With 1mm clearance from relief to the edge of the valve that should allow you to run 49/37 valves at maximum. Not that you would ever need to but interesting.
In the original 901 head design the valves were set with an included angle of 59 degrees. The inlets were inclined at 27 degrees from the vertical and the exhaust valves at 32 degrees. The next data point I have is the included angle for the 3,0 RSR, inlet was inclined at 25.5 degrees and exhaust at 30.25 degrees (so less by 2.25 degrees than the previous heads). This suggests that the included angle of the 2,2-2.7 heads was 58 degrees
According to my guesses from the diagram, the "opposite side" or distance from the center of the pin to the top of the relief is 52.5mm, which gives you an included angle of 26.22 degrees? Am I close?
1966 911 #304065 Irischgruen
Here is a little more information concerning the valve cutouts.
This piston was originally drawn to suit a 906 style head and valve sizes but has now been re-drawn to suit an FIA spec engine.
I will look at all the other detailed comments you have made and reply shortly.
Estimated weight 325 gms
Thank you for the input
Last edited by chris_seven; 03-01-2011 at 09:59 AM.
Chris:
Any progress? Dying to see some pics 'in the flesh' so to speak!
t
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