Piston specs needed for a 4.1
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turbofabricator
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What reference are you needing? Regardless, you still need to measure EVERYTHING......twice. Pin heighth, rod width, rod length, deck heigth, ring pack, back up oil ring or pin plugs, CC of combustion chamber, head gasket CC, bore diameter, stroke, dish depth, crown thickness, pin diameter, pin weight, taper wall, or drilled pin, dish or reverse dome, desired compression ratio, alloy. That just about does it.
Sorry for spiking blood pressure, I'm not doing a mail order build. Wanted a ball park figure on piston CH. Compression height = block height - rod length - (0.5 X stroke) Generally speaking 9.535- 6.35- (3.625 x .5) = 1.3725 CH
I understand that the numbers will change a bit. I've read that anything over 1.250 is better for the street. Does it make sense?
http://www.strokerengine.com/RodStroke.html
I understand that the numbers will change a bit. I've read that anything over 1.250 is better for the street. Does it make sense?
http://www.strokerengine.com/RodStroke.html
turbofabricator
Well-Known Member
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- Mar 7, 2004
- Messages
- 4,261
Yes that makes sense in regards to ring pack. With low pin heighth, the oil ring ends up in the wrist pin boss and requires a back-up ring or pin plugs. Don't worry too much about using a back-up ring on a street engine, they work fine. The other concern is the relation of the top ring land to dish and or valve reliefs. It gets pretty thin in those areas which will crack. Real thin rings are not a real solution with boosted applications, either. Less surface area to cool the piston. Oil squirters would help with thin rings, though. (providing the oil scraper isnt too thin for the added volume of oil that'll end up on the cylinder wall.
By the way, my blood pressure is fine. I take lots of meds for it, and there ain't no way you could aggravate me more than a select few co-workers (or politicians) do. I throw shoes at my TV during the news..........that helps blood pressure, too.:biggrin:
Always OK to ask a question. I just didn't understand what you were trying to decipher. Any of the aftermarket piston manufacturers can get what you need.
By the way, my blood pressure is fine. I take lots of meds for it, and there ain't no way you could aggravate me more than a select few co-workers (or politicians) do. I throw shoes at my TV during the news..........that helps blood pressure, too.:biggrin:
Always OK to ask a question. I just didn't understand what you were trying to decipher. Any of the aftermarket piston manufacturers can get what you need.
sd-slider
NOWUFFO
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- Feb 22, 2009
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- 639
I too am getting ready to drop my 4.1 block off for prep and machining. I will be using the stock turbo crank, 8445 heads and custom forged pistons made for the build.
If folks have used the hypers in the past, can the pistons be made to match the specs of the Hyper H471P's?
If folks have used the hypers in the past, can the pistons be made to match the specs of the Hyper H471P's?
There's one more factor you left out. That math is for a ''zero deck'' piston. If you want it in or out of the hole a little, you adjust accordingly.
That's actually why I designed 'custom' off-the-shelf forged pistons. After a 1/2 second hiccup from a clogged fuel filter, I broke 2 brand new hypers in my 4.1 and had to take the engine right back out.
That only issue with making a forged piston 'match' a FMO slug would be the weight. Those things are freakin' heavy.
