Anyone have any hook ups? I don't feel like dropping $675 on Venolia's. A little too far out of my budget.It will be press pins and 57.92 cc heads on a 1978 block. Anyone? Anyone? Bueller? Bueller?
Jack
Anyone have any hook ups? I don't feel like dropping $675 on Venolia's. A little too far out of my budget.
Jack
If you want forged pistons you are kinda in a rut, I have a set of TRW 2382P .030 over that are good for 9.5:1 on the later heads. However at this moment they are going to Canada for use.
You might want to look into the Kieth Black Hyper pistons, they have introed a few new ones for the AMC 390/401 crowd.
http://www.kb-silvolite.com/performa...1&RodLen=5.858
I have been thinking of going this way.
-RJ
1978 Jeep CJ-7 on Won-Tons :D Nv4500/4:1 SOA on ALCANS and mtr's
Nice! Daddy like! So I see one is for 9.5:1 with my heads and one is for 10.9:1. OK, so this leads me to a few questions.
1) That second piston is a little too high of a compression for pump 93 octane, isn't it?This thing will be for a weekend run about vehicle, not a daily driver.
2) These pistons are cast, not forged, correct? So how do they hold up?
3) What in the world does Hypereutechtic mean? (excuse the sp!)
Oh, and FYI, Summit has the 9.5:1's for only $386.49. If these will work for 80K miles (keeping the engine under 5000rpm), then I am sold!
Jack
OK, so my friend told me that hypereutetic pistons actually have a higher silicon content that other pistons, making them stronger. Don't know if this is true or not, but just thought I'd pass on the info to everone! Anyone else know of any additional info?
Jack
the Hypertectic pistons do have a have a higher silicon content and are stronger, however I have read that they are prone to breakage if exposed to NOS or engines with detonation problems.
Hypers come in between cast and forged pistons. They KB are a nice pistons, but they are still not a drop in fit, they use a smaller chevy pin so you would have you have your rods setup for bushed pins. They do this for a few reasons, chevy pins are cheap, (many many more made then AMC 1" pins) Also, they are lighter reducing, so make sure when/if you use them you have your engine balanced, and actually if you are running anything other then stock pistons you should do this anyways.
-RJ
1978 Jeep CJ-7 on Won-Tons :D Nv4500/4:1 SOA on ALCANS and mtr's
Hyperectic pistons are a good choice, when getting a set have the skirts of the pistons coated with (cannot remember if it is ceramic or teflon type item) they will last longer. They are also more forgiving under more than stock horsepower numbers.
Cool, thanks fo rall the help guys! I sent an email to KB about everything I heard here. I will keep ya updated with what I find out!
Oh, I borrowed this from Keith Blacks tech page:
"Hypereutectic -vs- Forged Pistons
Hypereutectic pistons are used in some original equipment engines. They are favored because of reduced scuffing, improved power, fuel economy and emissions.
Hypereutectic 390 refers to a unique aluminum piston alloy that contains dissolved and free silicon. The material can be T6 heat treated to high strength and stiffness. Non-heat treated 390 hypereutectic alloy aluminum has slightly less strength than conventionally cast F-132 aluminum.
With this in mind, we caution the reader about the use of non-T6 heat treated O.E. design hypereutectic pistons for high performance. Silvolite and others do make replacement-type hypereutectic pistons that are worthwhile for stock replacement applications. Original equipment design is almost never suitable for performance applications.
The KB line of hypereutectic pistons were designed around the 390 alloy. The result is a high performance part intended to give the performance engine builder access to the latest in piston technology.
Forgings have long been the mainstay of the performance business and did well in the big cubic inch engines of the 60’s. Now, with focus on peak cylinder pressure timing, ring sealing dynamics, cylinder air tumble and swirl, combustion chamber science, and extended RPM ranges, we need to consider some new piston options.
The KB T6 hypereutectics are considerably different than the forgings. The KB pistons have shown improvement in power, fuel economy, cylinder sealing, service life, and cost effectiveness. The reduced thermal expansion rate allows the piston to be run with reduced clearance. A tight piston is less likely to rock, make noise, and burn oil. A rocking piston wears rings and increases blow-bye. The close fit of the KB piston allows the piston rings to truly seal, minimizing blow-by.
The design flexibility enjoyed by the KB series of pistons has an advantage over present day forging practices. The die for a forged piston must be designed so it can be easily removed. This limitation makes it difficult to make a light weight piston without sacrificing strength.
The KB pistons' utilization of the permanent mold with multiple die parts allows undercut areas above the pin hole and material distribution in the skirt area that stiffen the entire piston unit. The forged piston requires thick skirts to achieve comparable piston rigidity. A rigid piston rocks less in the cylinder and improves ring seal.
The forged pistons' thick skirts add weight. The design of KB pistons gives us the option to build the lightest pistons on the market.
Some current KB pistons are not super light for several reasons. If the piston is to be used as a stock replacement, more than a 10% weight reduction will mandate that the engine be re-balanced.
Common sense suggests that the introduction of a new product be extra strong at the initial release. As the product becomes accepted, weight reductions are scheduled as regular product upgrades, as justified with actual race testing.
There will always be a market for custom forged pistons. Small runs of forgings are more economical than small runs of permanent mold pistons because of the complexity of permanent mold tooling. Where quantities justify, expect to see future KB pistons developed that are lighter and stronger than anything else on the market. Machined head profiles are easily changed with our CNC equipment so we will stay current with new cylinder head developments. Volume production is expected to keep the price reasonable.
Our pricing policy has given the impression to some that we are building an economy, or in between, piston. The truth is, we are striving to build the "State of the Art" piston that is best, regardless of price. Reasonable pricing is just an added benefit."
Jack
OK, so I called Keith Black today about the KB354 (9.5:1 compression ratio pistons) and asked if you have to run Chevy pins, or if you can order them for stock AMC pins. Looks like you can only get them for Chevy pins. Dang it! Doesn't make much sense.Not sure what to do now. Guess I am gonna just keep on hunting for some pistons. Dang it, and I though I had it all figured out.
Oh well, I am gonna go start drinking now.
Jack
The deal is that it is "cheaper" for KB to sell you chevy pistons and you custom fit them to your motor than it is for KB to retool to make a line of pistons that there realy is no market for. 80% of the market is chevy and we fall under the other 20% I was told, but I really know AMC is probably just 1% if that much.Originally Posted by Lifted79CJ7
OK, so I called Keith Black today about the KB354 (9.5:1 compression ratio pistons) and asked if you have to run Chevy pins, or if you can order them for stock AMC pins. Looks like you can only get them for Chevy pins. Dang it! Doesn't make much sense.
Jack
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