coyote42
Well-Known Member
Looking for opinions on pistons for a 340 street motor. Hyperutectic or forged pistons?
Hyperutectic VS Forged pistons
- Thread starter coyote42
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UOP
Well-Known Member
What is the plan for the rest of the build? If you're planning on making a bunch of power with forced induction or nitrous, forged would be the way to go. If you're just building a driver that may one day have a 100 shot bolted to it, hypers would do just fine.
OldmanRick
Well-Known Member
With no spray or boost i'd choose hyper's. In most cases the regulation off the shelf stuff is usually lighter then forged and easier to balance. I assume being a street engine that a reasonable rpm limit would be used in the build 
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66340SEDAN
FABO Member #3649
I have KB forged in my 340
1968FormulaS340
Well-Known Member
If you are just building a pump gas street engine I would go with cast.
crazy 340
Well-Known Member
I ran hyper with nitrous with 12.5 c.r.
and alote did I said alote of over RPM
and alote did I said alote of over RPM
1970Duster
Well-Known Member
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Ross Racing forged aluminum pistons.
UOP
Well-Known Member
You say street, I say hyper ((street, hyper...street, hyper)).
:sign5:
dustinmoran91
Well-Known Member
the piston type (cast, hyper, forged) won't gain you any power in its self. the power gain comes from the shape, I.E. domed, dished, and shape of the two for flame travel and quench. if its just a street motor with no power adders for seen in the future then id go cheap and just get cast. unless you want a piston with a dish or dome that's not available as a cast piston and only available as hyper or forged in which case i would go cheaper again and run hyper. the only reason i can see buying forged pistons is if you needed them for boost or nitrous.
N/A 400ish hp 10:1 or less compression with little or no strip time Hyper's do but I'd go forged its best to build the best short block you can, you'll always want more power latter maybe do some racing and add a shot of Nos which will all be limited by your piston choice.
550+hp and 7500 rpm with hypers... NEXT!
IF you are building a street engine and want to save some coin, use hypers.
Gonna run it high rpm (7K +), hit it with more than 125 of juice, start looking at forged.
Just gap the rings to at least the specs the manufacture recommends.
IF you are building a street engine and want to save some coin, use hypers.
Gonna run it high rpm (7K +), hit it with more than 125 of juice, start looking at forged.
Just gap the rings to at least the specs the manufacture recommends.
kjelledart
Member
kb hyper best street and strip !!!
dwire67
Well-Known Member
:sign3: I have over 150 runs on my KB Hyper pistons and I just redid the engine and they where fine , I also twisted my engine to 7500 no problems
coyote42
Well-Known Member
Thanks for the input.
Fisher
Old Guy with a Cool car.
I just had this conversation with my engine builder today. I am going with a forged piston and aftermarket rod. Building 10.5-1 compression 340 with Lunati solid flat tappet cam.
forged. dont try to save a few bucks on valvetrain or shortblock strenght it will just come back and cost you more in the long run.
anyone else seen a hypereutetic piston after a misshap? i have seen more than one,they shatter like glas when they break.
anyone else seen a hypereutetic piston after a misshap? i have seen more than one,they shatter like glas when they break.
MiradaMegaCab
Well-Known Member
I ran a Mopar Performance short block with the hyper pistons for years.
6psi of boost and upto 150 shot of N20 at the track. I also did alot of street driving.
I cracked the skirts off 3 pistons while in boost and spraying with a 150 shot. During that run I spun on the 1 to 2 shift and only had 4psi of fuel pressure. I dont know how mant RPMs the engine was at cause my tach only goes upto 8000 RPMs, and it was burried. The piston tops werent damaged at all. I did step upto Diamond forged pistons on my current setup but I am still impressed with the hypers.
6psi of boost and upto 150 shot of N20 at the track. I also did alot of street driving.
I cracked the skirts off 3 pistons while in boost and spraying with a 150 shot. During that run I spun on the 1 to 2 shift and only had 4psi of fuel pressure. I dont know how mant RPMs the engine was at cause my tach only goes upto 8000 RPMs, and it was burried. The piston tops werent damaged at all. I did step upto Diamond forged pistons on my current setup but I am still impressed with the hypers.
Nobody will spend your money faster than OTHER people.
It's all about what you plan to do with the engine. Figure that out and select an appropriate piston.
Normal street driving and running at the strip, no need for forged.
It's all about what you plan to do with the engine. Figure that out and select an appropriate piston.
Normal street driving and running at the strip, no need for forged.
dodge freak
Well-Known Member
My KB243 are doing fine, its hard to find .040 over 340 piston that is forged..my builder had to talk me in to them and for $245 bucks they were my cheapest option
My 340 gets buzzed every time its out...done all sorts of hard driving, from flat out for too long, to 4 -5 grand for an hour on the freeways, not a peck of blue smoke from the exhaust ever
Just back off the timing, KB calls for 32 degrees all in and be sure the ring gaps are large
My 340 gets buzzed every time its out...done all sorts of hard driving, from flat out for too long, to 4 -5 grand for an hour on the freeways, not a peck of blue smoke from the exhaust ever
Just back off the timing, KB calls for 32 degrees all in and be sure the ring gaps are large
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