|
In the near future I want to try it. Piece together an sr block and clean the living F out of it. Assemble using mostly FSM and oem parts if necessary. I'll rent the dial bore gauge and indicator tools to make sure its round with a deck plate strapped how I want to run the head and compensate in fastener torque if necessary for slight deformation, if it even makes a difference. Its not 1000hp so I don't need special O-ring or head gear. Stock head gasket would even work but I would just use a cometic or typical multi layer steel. You don't want a strong head gasket on a daily driver build, just in general, but I won't have any tuning issues so I am not afraid to use MLS. If I was unfamiliar with the application I would def use OEM HG though, first.
Avoid the machine shop by dealing with the cylinder walls and ring selection personally, or find another block. I would weigh the cost of new blocks against success of finding good blocks, against the cost of using OEM pistons with existing blocks. If we give it some extra budget, I'd like to find an OEM +/-0.00XY style drop in forged piston like they have for LS engines with easy to hone at home, skip machine work. After accurate measurement, call the various companies and ask I guess. "do you carry SR forged for drop in OEM cylinder? Ya what is cylinder wall recommended clearance... uh-huh and how should the cyl walls be prepped for those rings? What is alloy of piston?" collect data see if you can make it work.
Then Simply measure and look for perfect fits by chance. It sounds crazy but I think the piston will be a little tight by design which allows for hone to take some 1 thousandth give or take. Before purchase make sure the manufacturer is willing to work with you on sizing somehow (if I get a piston that is .0008 too tight can I send it back for a re-fit, etc...)
Its a tedious process but if you manage to calculate correct piston-wall clearance for each correctly to fit with the required cylinder wall finish given the type of ring provided, it would work as well as if any machine shop did it in theory. I would def do your own calculations based on piston alloy and high temperature, i.e. (mechanics of materials) expansion coefficient to find out total diameter in bore at high temperature 2200*F 2500*F 3000*F etc... for that alloy and starting diameter. Find the margin of safety/error in piston'wall clearance or find how the piston manufacturer came up with that number (ask?). Sometimes you can run a less expansive forged piston alloy tighter. The manufacturer is assigning some number based on max temp so to err on the cautious side (since nothing is perfect) which way will you go, just under or just over? For my daily driver, I would be under, but a racing application would be over. A racing application wouldn't use an low expansive alloy though. So it depends on how the manufacturer approaches the problem of stock bore sizing in daily vs racing applications, do they offer STD bore forged piston in a high expansion alloy? (they actually do because you can buy brand new blocks sometimes, summit sells them for engines with new blocks available, but they are labelled as "street friendly" alloy which I have to wonder at) And if so, how many thousands less in diameter will it be than the stock unit. And then there are .005" larger forged which I presume is for weathered OEM bore with mileage, hone it just right and you have a forged piston with no machine work needed in the bore.
Balancing is the issue and actually getting a good hone (could take more or less than you wanted), many potential failure spots hidden I am sure. I would likely just use OEM piston.
Then try to get 100k+ out of it with ~500rwhp
I think it's entirely possible 1 person does everything including tuning and has enough experience.
Hopefully thats the message the first post is sending
IMO
even with 100year experience and super mechanic skills, stuff just goes wrong sometimes. There is a luck involved in many aspects. Do not attempt if you don't feel lucky
|