Pistons for a street 510-520, gas ports?

[Joey120373]

Thanks Brent.

[Gaugster]

Hey Joey120373.

Can I ask what your final piston order details were? I am looking to grab a set of pistons too and have to answer the same questions. TIA!

[Joe-JDC]

I have heard some feedback on the lateral gas port rings, and the consensus so far seems to be very positive.  Better even than the ports in the piston lands.  Ring seal is better with less twist, and cylinder wear is better for leak down tests, etc.  Seems the rings don't tend to buckle with compression as bad with the lateral grooves in them, and they run cleaner.  Joe-JDC

[gt350hr]

  Joe ,
     I saw the data Lake Speed jr gave to us from a test at Shaver Specialty on a current 410 alcohol sprint car engine. The increase was about 6 HP MAX in the 4,000+6,000 rpm range and was about the same at higher RPM to a gas ported piston. This was against a lateral gas ported piston NOT a vertical gas ported piston. Yes there is a power difference. "I" do not see how a ring with varying thickness can stay "flat" when subjected to heat like that of combustion heat.
    There is a DISTINCT advantage to using this ring design when "gas ported pistons" are not allowed. ANY time you put cylinder pressure behind a ring you will have better seal and more HP.

[Joey120373]

.  Hey Joey120373.

Can I ask what your final piston order details were? I am looking to grab a set of pistons too and have to answer the same questions. TIA!     

Guagster, I will try to look up the build sheet on the pistons, I tried to respond to your PM yesterday but it did not go through.
I am currently working 16 hour shifts at night with no cell service and very limited internet, so it may take a day or two for me to scrounge it up and send it .

If I recall, my pistons are pretty much the same as what Jay has in his motor, except that they have a 30cc dish to get the CR down for pump gas.

[Gaugster]

.  Hey Joey120373.

Can I ask what your final piston order details were? I am looking to grab a set of pistons too and have to answer the same questions. TIA!     

Guagster, I will try to look up the build sheet on the pistons, I tried to respond to your PM yesterday but it did not go through.
I am currently working 16 hour shifts at night with no cell service and very limited internet, so it may take a day or two for me to scrounge it up and send it .

If I recall, my pistons are pretty much the same as what Jay has in his motor, except that they have a 30cc dish to get the CR down for pump gas.

It's very much appreciated. My 390 based build (460 CI stroker) is calculated to be 10.4 : 1 with a 21cc dish. But I still have to confirm my target deck height etc... so very much a keyboard exercise.

[Joey120373]

Bore: 4.350”
- Stroke: 4.375”
- Pin Diameter: 0.990”
- Rod length: 6.700”
- Block Deck Height: 10.150”
- Head Gasket: .041”, 4.400” bore
- Cylinder Head: FE Power or standard FE
- Combustion Chamber Volume: 69cc
- Static Compression Ratio: 10.77:1
- Cam Specifications: 255/265 @ .050”, 0.800” Lift, 117 LSA
- Gas Ports: Lateral
- Top Ring: 0.9mm steel
- Second Ring: 0.9mm Napier
- Oil Ring: 3mm, standard tension
- Pins: Standard pins for 0.990” diameter, fitted to pistons



These are the notes from the invoice, the ring thickness did change though. Evidently with my bore size, .9mm rings are not available, so they went with .041 for the top and second ring.


I ordered them in late February, so I suspect they should be arriving any time now.
That will be a landmark moment as I can get the machine work started on the short block.....

Need to get a hold of Brent again and get the cam and lifters on the way.

[blykins]

Gotta have a machinist that's really on top of things to use a .9mm ring.  A .043" top ring would be 1.09mm.  You're not losing anything power-wise, it's really diminishing returns after 1.5mm, unless you're looking for low single digit horsepower gains.