Looking to purchase a new set of pistons. I am told they are custom arias pistons. I know nothing about these pistons, other than I'm sure the compression is over 10:1 because of the high dome.



I am unsure what the compression will be, or even if its a good choice or not. I'm not sure how you know whether the piston will hit the head or not.

I have a b16 head, which was milled, unsure how much. The b18b1 was also milled. 83mm pistons, stock thickness head gasket, ls crank, ls eagle rods. my goal is roughly 500whp, and I will be running water methanol injection 50/50 mix. I plan to run as much boost as possible on my 60 trim. Thanks in advance

 

umm thats quite the dome there...


just go buy a set that you know what you are getting. go for a 10:1 compression give or take

 

Sounds like you don't know much at all there guy. That dome is surely at least 12:1 at a glance and almost surely higher. You should probably just pick an engine builder and let them do all the dirty work for you.

 

a 10:1-10.5:1CR piston will have a flat top. these look to be well over 12:1, possibly over 13:1. can whoever has these pistons give you the spec sheet data or the piston part number so you can contact the manufacturer and get the spec sheet data?

that's the only way to get a true compression ratio number (using an engine calculator, available online)

also you need to ask what wristpins come with it.. wall thickness, are they straight or tapered?

then the pistons... what alloy, is the material of the dome thick enough to handle forced induction? most high compression pistons, custom or shelf pieces, tend to have thicker dome material. this is done to make the piston lighter as NA pistons don't need thick dome material because they won't see high cylinder pressures like FI apps

(muckman can tell you all about running a high compression NA piston in a turbo motor, as well as what happens when you run small wall, tapered wristpins. he found out you need pins that are .120 wall and straight, not tapered... when he ran the "shelf" high CR piston and the included wristpins he bent all 4 pins around the 500hp mark)

so you need to get the spec sheet and custom part number from whoever has these pistons and then call the mfg with this info and see if they will withstand the rigors of a turbo motor, then you need to go online and use the Honda specific compression calculator found here..

http://www.zealautowerks.com/bseries.html

this is the best one by far as it has all b series data stored... from deck height for each b series block to crank stroke, OEM piston specs (every b series piston), combustion chamber sizes, headgasket thicknesses, etc.

so you can select which block, head, and crank you are using and then entire the piston data off the spec sheet you get and you'll get a damn accurate compression ratio.

but just looking at the overall piston profile tells me these are way up there in compression, like I said.. at least 12-13:1 static CR... which would require E85 or race gas... or you could try 93 with a ton of water/meth injection, at least 70% methanol

so try to get the spec sheet and part number from the seller then contact the mfg and see what they say about using this particular piston in a turbo app, then entire the data in that calc I posted and go from there.

 

also if you did use these pistons, having the block or head milled means you'll have to clay the motor to check for piston the valve clearance to make sure you won't have issues with contact

it might not be so bad with any OEM cam but if you upgrade to a more aggressive cam like the GSC T1s then I'd be worried. you'd probably have to play with cam timing to avoid both piston to valve contact and valve to valve contact (the last one you only need to worry about if you have oversized valves)

 

It looks like the piston have bigger, deep valve pocket to accomodate bigger cams. I won't be surprise if these pistons are being used by some big HP application 1000+whp.

 

Why would you buy UNKNOWN custom pistons? And why wouldn't the seller know what he's selling? Just go buy new pistons in whatever size and compression you want.

 

 

Those are really high compression pistons…those wrist pins are tiny too. I would definitely do HD pins no matter which piston you get.

 

thats why I made this post..

The guy said he has the specs of the pistons. He said the compression is 11:5 with a gsr head.

 

Ive got 12:5 pistons next to me on my desk and the dome on yours looks considerably taller, granted mine don't have nearly as deep relief cuts id say those are higher comp than 11:5...personally unless they are practically giving them away id look for an off the shelf piston for the comp you want....

 

You could always measure the dome volume and run the calculations yourself..

 

Travis forget the unknown and buy what you want and if boosting a higher compression piston buy a quality piston And upgraded wrist pins. My arias are 11.3 in my setup and I'm running tool steel pins. Overbuilt is always better than just enough.

 

lol yea in a b16 block

 

Couldn't have been said better.

 

if he has the spec sheet tell him to send a pic of it or tell him to copy all of the data so you can enter it in that calculator I posted. then you'll know for sure what the compression ratio is

there's no way those are 11.5:1. if they are I'll give you all of my parts lol. that dome looks similar to CTR pistons (PCT) which in an ls/vtec yield 13.93:1 with a b16 head and 14.35:1 with a gsr head

so you need to ask him for the data off the spec sheet so you can calculate it yourself and find out for sure what CR is