Piston Choice on 318

Small Block Mopar Engine

  1. 69charger

    69charger Well-Known Member

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    alright so I want to bore my 318 .40 over and im most likely gonna be running stock rods and crank unless i run across something but anyways i'm not sure what brand of pistons I should use.
    maybe go Speed-Pro? Keith Black?

    I'm thinking Hypereutectic either way but im pretty green on the whole subject so I really need some help here

    oh, and why are there a couple sets of hypereutectic that cost as much as forged... :-? that didnt make any sense to me
     
  2. mr.318

    mr.318 Well-Known Member

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    i'm happy with my k.b. 167 pistons in my 40 over 318,they get you close but i had my zerodecked to,
     
  3. 69charger

    69charger Well-Known Member

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    yeah I was gonna zerodeck mine too im pretty much basing my build off the Enginemasters 318 article and the Hot Rod one about the Hi-po 318 they seem to get about in the 400hp range and thats about where I wanna be.

    I've been reading up a bunch and it seems like its the way I wanna go financially wise too,
    I just recently purchased some 340 J heads But after reading some posts on here it seems that i should have gone the way of a smog era 360 head but i figure i could save the money on the J heads cause they already have the bigger intake and exhaust valves that I was going to get machined on the 360 heads anyways.

    but im going off on a tangent...

    if you guys wanna get a feel of the build I'm wanting to do then I'll post some links here in awhile to the hi-po builds so if you could suggest anything else as well that'd be tons of help
     
  4. tobysoldblue

    tobysoldblue tobysoldblue

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    the valves are too big,the engines will lose its intake velocity,unless your gonna turn it up to 7000 rpm or above.Thats what all the engine guys are telling me any ways.I am building my 318 with federal mogul flat tops,block not decked,302 casting heads,ported(by me)milled .30,mopar thin head gaskets,lunati voodoo cam,with 494 intake,513 exhaust lift,weiand stelth intake,750 holley vaccum secondary carb,904 with 2500 stall converter,and prob 391 gears.I dont know what its gonna do,but the parts are already in there way,and well see how it runs
     
  5. dodge freak

    dodge freak Well-Known Member

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    Well I did not listen and swap some 308 high swirl 360 heads with the 2.02 intake valves on my 318. Had the chambers milled to 63cc's.

    My motor makes more power everywhere it seems like and I rev it no higher than 6000 rpms but it does have 3.91 gears.

    I hear those hyper pistons crack easy if the motor pings but nobody makes a high compression forged piston for a 318??
     
  6. needsaresto

    needsaresto Well-Known Member

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    Kb is the only choice for a hi comp piston.I looked extensively a while back. The avg comp height for a cast piston runs between 1.72 and 1.75 roughly. Kb 167 height is 1.81. With magnums heads 10:1 is achievable.

    So yes hyperuetectics are brittle due to the hi silicon content. I wouldn't use them if you are planning on nitrous. They are fine for most uses in street engines.Some guys race em,but forged would be better.

    Actually I remember one other brand but it's cast.The only info I have is here.

    http://chucker54.stores.yahoo.net/sppropisewmo.html

    Not sure what head thier basing that 8.5 comp ratio on.
     
  7. 73DartSport

    73DartSport Well-Known Member

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    8.5:1 is stock CR for most 318s. I dont see a flat top piston with 2 valve reliefs being that CR unless those are for a magnum application, which if I am not mistaken is what you need for magnum heads is 2 reliefs. LA style heads should be one relief with a flat top piston if you are approaching 9:1 or just above that mark.
     
  8. 69charger

    69charger Well-Known Member

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  9. 69charger

    69charger Well-Known Member

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    oh and thanks for the heads up on the valve reliefs 73dartsport
     
  10. mr.318

    mr.318 Well-Known Member

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    yea i didn't listen either i'm useing 360 heads with 202 -168 valves,on my 318 way better, than the 318 302 casting heads i had, i've got 355 gears almost a second faster with the 360 heads, and my timeslips prove it,
     
  11. 73DartSport

    73DartSport Well-Known Member

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    I'm using 360 heads as well just for the extra flow that comes from them. The heads I have are 68cc heads and with Keith Black's 167.040 ((block is .040 overbore)) pistons I should attain right around 9.1:1 for a compression ratio. Combine all of this with an Edelbrock RPM Air Gap Intake and my fuel mixture should be awesome as it dumps into the cylinders. Might not be what everybody is looking for, but I see it being just what I am looking for. Will report more when engine is complete and fired up, which, hopefully, is soon.
     
  12. 69charger

    69charger Well-Known Member

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    I dont mean to be rude or anything but I'm asking about piston choices and some tips on choosing the right ones...or suggestions on what company to go with.

    I dont know how this topic got changed to cylinderheads
     
  13. 73DartSport

    73DartSport Well-Known Member

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    It didn't really changed to cylinder heads, just helps to expain how the choice of pistons came around. Pistons alone do not an engine make, and without matching up the right components with any piston you could come up with major disappointment. Many on here will advise you to not use 360 heads on a 318 because of loss of compression, but we were just simply helping you understand that with the right combination of parts you can still obtain a CR that is considerably better than stock.
     
  14. sublimeswinger

    sublimeswinger SUBLIME Senior Member

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    Agreed

    Your choice is simple. KB167. They are the best piston for the money. In a prevous post some said they are not good for the juice. Thats bull! The problem is that people dont gap them to the KB specs for juice. If you change to the KB's, you will have to have the engine balanced IIDR. Because they are lighter. Im sure some one will correct me if im wrong.

    Go with the KB's have them set to zero deck or just use Mopar thin head gasket.


    P.S. Is that a pic of Dimebag? He is missed!
     
  15. 73DartSport

    73DartSport Well-Known Member

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    BTW: Just a side-note here--

    You may be very faithful to your local guy about wanting to buy all of your parts from him, but here's how the rundown of prices went for me when I ordered my KB167.040s which is the part number you'll need if you go with them for a block bored .040 over...

    My local friendly parts supplier-- $386 and some change for the set

    Jegs-- $49.99/Each-- $399.92/Set of 8

    Summit-- Sells the set of 8 for $236.99

    Don't know if you can find the cheaper anywhere, BUT make sure you shop around bro. I did and it saved me almost $150. Don't know if money is an option to you or not, but that's a good extra chunk I can put on something else for the engine.
     
  16. dodge freak

    dodge freak Well-Known Member

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    Jegs and Summit match prices too but you have to ask.

    I found plugging the part number and item on google, you can find other sellers. Like speed shop warehouses that have better prices than Summit and they will match them. E-bay no.
     
  17. 73DartSport

    73DartSport Well-Known Member

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    That's a good idea as well, like I said...always helps to shop around.
     
  18. 69charger

    69charger Well-Known Member

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    Sublimeswinger and 73dodgesport thanks for the info thats exactly what I was looking for.
    and dartfreak thanks for the heads up on pricematching im definitely going to go that route.

    yessir it is and he is surely missed.
    dimeforever.
     
  19. 318ute

    318ute Active Member

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    69charger,
    Apart from the KB167 you could also look at the KB399 especially if your after good compression out of the box.

    If you want forged, I am not sure if these are suitable but KB also list the following options under forged!
    KB844, KB845 & KB847.

    318ute.
     
  20. 1966DDart

    1966DDart Well-Known Member

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    I might be a little late posting to this thread but what that heck!

    If you haven't bought pistons yet, I'd recommend looking at Wiseco "ProTru" forged pistons. They make both a +0.030 and +0.040 pistons for the 318....AND they have a 1.800 compression height!

    For more info on the pistons....

    http://www.wiseco.com/PDFs/Catalogs/PT08/BuickChryslerChevrolet.pdf

    The best price I've found so far... (and where I just ordered a set for myself),

    http://www.flatlanderracing.com/

    Also, I called Wiseco to check weight, they are 532 grams and come with a 132? gram pin.


    -Phil
     
  21. needsaresto

    needsaresto Well-Known Member

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    Hmmm,I thought they were pricey at first glance but they are forged,come with rings ,pins and locks.

    I bet Summit would beat that price.But do they carry wiseco?
     
  22. dodge freak

    dodge freak Well-Known Member

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    Thanks, they look good. I am not too nuts about those hyperuetectics pistons. You go too lean on the A/F or give it too much timing you be looking for a whole new motor.
     
  23. sublimeswinger

    sublimeswinger SUBLIME Senior Member

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    There almost twice as much as the KB's. IMO the KB's are the best piston for the money for a 318
     
  24. 73DartSport

    73DartSport Well-Known Member

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    I still have to agree that KBs are the way to go. I have talked to a lot of people that run KBs and have never heard of a problem from anyone.
     
  25. needsaresto

    needsaresto Well-Known Member

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    I do seem to recall some question as to whether they could stand up when they first came out. Hi silicon content leads to brittle metal,and it was felt shattering could be an issue.

    I dont think it has been. But Im carefull. Nitrous abuses the internals something fierce. Seems to me a forged piston would be a better option.

    I dunno. Would you prefer a cast hyperuetectic wrench over a forged one?LOL!
     
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