Well i was checking around summit after ordering an edelbrock header for dirt cheap and I saw they had the arias pistons for a D16a6 on clearance for $291.50 so i did some researching and and calculation. So I wanted to know if my calculations were correct that those pistons will yield an estimated 11.9:1 CR on a D16y8 with a y8 2 layer headgasket.

The summit part number is ARA-3330000-NR

and the specs for those pistons from the Arias Website are:

Dome Top
Bore: 75.05
Compression Height: 1.166
Dome cc: -0.3
Estimated CR on a stock D16a6 Head: 10.5:1
Gram Weight: 242

I believe that is a really nice compression for the street for those that don't want to run a sky high 12.0:1 to 12.8:1 CR that you get from the p29 or pm7 pistons plus the arias are forged and are perfect nitrous or supercharged if i'm correct!

 

From when i was planning my d-series na build...I've read many times and was told that running non-vtec d16a6 pistons into a vtec motor(d16y8 example) and a high CR, there could be a possibility of the valves smacking the piston as they aren't cut with the proper depth valve reliefs that the vtec pistons have.


If somebody finds this info totally wrong, please correct me

 

Call Tom Jung at ARIAS and ask...310-532-9737

 

man i hope not cuz that deal is to good to pass up but can't the valve reliefs be modified slightly?

 

the A6 valves are about 1mm smaller in diameter than the Z6/Y8 valves. There is also valve angle you have to consider when using a piston that is not intended for that head combo.

you can machine the piston down to accept the type of valve you are using..

 

CRAP!.....now u tell me. i bought sum P29 piston already and it bump the compr to 12.5......i wanna lower it to atleast 11.1:1. should have start shopping a bit longer ...o wells. maybe ill switch to these piston for my FOhDOH..

 

yes the valve reliefs on the piston can be modded. Im guessing your local machine shop should take a look @ it and let you know if it could be done. Im not sure how you would have them acually do it. Maybe you would have to fill your whole combustion chamber with clay ending the clay at the end of the head. then they would add the size of your H/G ie 0.025(y8 2layer)that would be your deck height. Then you need to make sure that you have at least .60 mm (60 thou) or 1/16 in between the valve and the piston at full lash. I got 11.55:1 cr with that setup. with a comp height of 26.91 with zeal calculator.


you might just be able to run these if you do have the clearance but.... Im no exbert but i would think there would be alot of disruption due to the valve reliefs not matching the piston and it would hurt power in a street app. And be more likley to cause detanition. If you didnt have machine work done to them ....
But i bet you would spend more than the difference getting the machine work to the piston than if you just paid $400 for another piston.

so i would pass on these if you dont have an a6 head.

hope that helps a little hopefully other's try to give you more advise.

i got that jg header too its sweet!.

 

Yeah well i decided not to get the pistons seeing that i'm going to run a cam that had a pretty big lift so I had to pass it up. But there was some guy on D-series.org running them with out any modification but he can only run at most a stage 2 cam. I'm probably going to start a build thread soon just waiting to get some more parts. I got the Edelbrock header awesome it's going to get modified next week i'm still waiting for parts on my custom exhaust it will be 2.5 in all the way from the header to the tail pipe. I'm going to be running a carsound high flow cat/ Magnaflow 24in resonator and n1 canister muffler. Hopefully it sounds good!