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piston weight and other stuff about pistons

Discussion in 'Engine Building' started by GSRCRXsi, Sep 12, 2004.

  1. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    ok, so im just doing some preliminary build ideas for my engine. im not doing anything anytime soon as i have no money or time, but im just brainstorming (dreaming in other words, lol)

    my question is about the weight of pistons. i had initially planed to use JDM ITR pistons in my gsr block. they are a direct fit for gsr rods. i was also going to combine this with a 2 layer gasket and ctr cams. this would raise my compression to the 11.6-11.7 range. was gonna tune it wiht probably just a vafc and some 310 injectors (not sure if thats even necessary)

    now i was searching on honda-tech and i came across a guy with a gsr block, itr head ported with ctr cams and b16 pistons. with just tuning from a fields vtec controller (stock injectors and fuel pump) he put down 195 whp and 140 trq and he ran a 12.9 on slicks with full interior, impressive. the b16 pistons will yeild a higher compression ratio and will probably eliminate the need for a 2 layer gasket to obtain the same 11.6-11.7 compression range. not to mention the fact that b16 pistons are easier to find and cheaper too. but are they also lighter? what about the strength? and arent the type r pistons coated thermally on the skirts?

    just looking for some opinions on which would be a better way to go. the b16 pistons? or the itr pistons? also tuning suggestions are welcome too but i dont plan to go uberdata, hondata or any of that other stuff, just too much hardware for me to worry about. this isnt some full out race project, just a mild build. mostly to be used for daly driving and occasional racing at the track, so reliability of the build will be an issue too.

    thanks.
     
  2. dood

    dood Junior Member

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    you got more answers at honda-tech.com...good luck with your motor bro
     
  3. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    all they did was tell me to run CTR pistons, lol.
     
  4. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    My post didn't go through? ???

    Run either the B16 or the CTR pistons- tuning and proper matching of parts will get you some pretty good power. CTR pistons in the GSR will give you some nice numbers though.

    Dummy math:

    B16 pistons = 11.7:1
    JDM B16 pistons = 11.93:1
    CTR pistons = 12.4:1

    The CTR pistons would definitely be streetable and not too hard to tune.

    The ITR and CTR pistons DO have coatings on them- I don't remember if there's a thermal barrier coating on top (don't think so), but the skirts definitely have a low friction coating. Here's a picture I took while comparing some other pistons- the center piston is the ITR piston:

    [​IMG]

    If you want really lightweight, go for aftermarket forged pieces that are meant for high speed all motor applications. You'll be really light then.

    :)

    [​IMG]

    For piston weight between the B16 and CTR pistons, I don't know how much difference there would be. They would both be pretty heavy because they're cast, but I would imagine that the weight difference would mostly be in the thickness of the pistons' dome.

    Strength- I don't believe that the R pistons are coated on top, so I don't think that they would really be any tougher than the non-R pistons. Since they have low friction coatings on the skirts (not thermal), they would be better for high revving, but tons of people have taken uncoated pistons up past 8000rpm without problems.
     
  5. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    thanks for the reply mike! very helpful. but im still torn lol. see the low friction thing is very apealing with the r pistons, but then the b16s are cheaper and wouldnt need a 2 layer gasket to bump the compression,

    i really dont want to run the ctr pistons. just not for this build. i just want something mild, and just having the compression that high would require more work and effort then i want to put into it. if i was going to run a build with this high of compression i would do it right and get everything reworked, forged pistons the works, and i do hope to make a build like that someday, but right now im just going for something subtle.
     
  6. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Just run the B16 pistons then. It's not like they don't hold up to 9000rpm or more all the time- tons of people run their stock B16 blocks to 9000 or more, whether or not they're making power. Of course, the pistons will be moving faster than they would be in a B16 block, but you should be ok as long as your oiling system can keep up.
     
  7. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    true, the gsr dois have better oiling of the pistons, with the oil jets and all. i think im gonna go with the b16 pistons. but now the choice, JDM or USDM ? hmmmm :)
     
  8. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    JDM. :)

    The compression difference between the two isn't really that big, so if the USDM B16 pistons are easier for you to get, you might just want to go with those. You'll still make really good power from them with well matched cams.

    If you can afford another $140 on your pistons, you could get them coated by Swain Technology like I did with my CP pistons up there in the photo- that would really buy you some longevity and give you the same friction reducing qualities that the R pistons, but you would also have the thermal coating on top. The thickness of the coating (.003in) would take your USDM B16 piston setup from 11.7:1 to 11.8:1 compression.

    It's an option you might want to look into. You would get the advantage of cast pistons by being able to run a smaller piston to wall gap (less noise) while also getting some of the toughness of forged pistons as well (because of thermal coating on top).

    FYI- my GSR block has the oil squirters blocked off. Swain Tech told me to not even bother with them, because the thermal coating on top of the piston blocks so much of the heat that the oil squirters aren't necessary. The squirters are there for heat removal anyway, not so much for lubrication.
     
  9. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    thanks mike! would there be any advantage to blocking off the oil squirters?
     
  10. MikeBergy

    MikeBergy Blah blah blah....

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    I'm not the mike you anticipated answering this, but one advantage to blocking off the oil squirters will be the gain in oil pressure, and this will preserve your bearing surfaces a bit better (like main and rod bearings :) ).
     
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