Ok, here is the deal. I have 2 sets of rods, and 2 sets of pistons. You will see in the following pics rods from a jdm D15B and from a D16A6. The piston options i have are the A6 and Vitara. Now, the rods appear to be the same, except for the stamp on the bottom-the JDM are M5:5 and the A6 are M5:2. Now, does anyone know if there is a difference in these rods AND what rod appears to be in better shape. The D15 are darker, but i dont know if thats bad or good. Next, I believe i have read that the A6 pistons will stick out a JDM D15 block a very small amount. Can anyone verify this, AND if it is true, is it still possible to use them. As in, will the valves clear it. Bottom line is im trying to put the best piston with the best rod out of the 4 possible combinations I have.

[IMG]local://upfiles/11033/3EAA5E5673EF488BB76DD55AAB9ED5DB.jpg[/IMG]

[IMG]local://upfiles/11033/2D63D7340D9A46BF9C0FFBBE8B08AAA3.jpg[/IMG]

Now, which rods look best suited for 9psi of boost, and is there a difference between them



[IMG]local://upfiles/11033/7298B42930434AA786FC5CED8C4A4A5A.jpg[/IMG]

[IMG]local://upfiles/11033/B2E806F4910B44CC9910E8ADF8DDD9AC.jpg[/IMG]

 

really, neither are that great for boost. i would look into some forged rods the price is well worth it, and you could run a lot more boost with them safely. if your engine is a d15b then both pistons might not work (becaus of the d15b shorter piston compression height). the only thing i could say is you assemble the engine and check to see if they will hit the valves, and do a search for a d series compression calculator to figure out the compression and everything.

 

Well, i was running 9psi on the rods before the turbo went and it did great. I dont have money for forged, and im not upping the boost. I know for a fact the vitaras will work, people with the JDM say we are limited to the P08 pistons that come with it, and vitaras. I dont know if other pistons are just close, or they actually hit. I have also discovered since my last post that someone is selling brand new D15b2 pistons for $50. Anyone know if these will fit? Im just sick of not having a car here, and i need to get it back together.

 

the thing about the d15b is that it is a d15 block and it uses a d15 crank, but with the longer d16 connecting rods, in order for the pistons not to hit, they need to compensate by making the piston shorter above the pin. so the d15b has a better rod to stroke ratio than a regular d series and that lowers the piston speeds making able to rev higher like a b16.

if the vitara pistons will for sure work, then use those because they do lower compression a good amount, so you would probably need to run more boost to make up for it.

but i do say if you have it apart might as well put forged rods in as a saftety measure, and for more performance ability. instead of 9 psi, like 20 psi.

 

D-series Compression Calculator

 

thanks chimera. ive been through all that, the problem is im not good at math, so i dont know what the results mean. the A6 pistons i get like a .03 piston to deck height, and im interested in the GX pistons and i get like a -.07 somthing. I have no idea what these numbers mean

Ok, so ive found a positve number on the compression scale means it will still be in the block. So, PMS GX pistons are looking good right now, however, i have A6 pistons sitting around that will yes poke out a little, but still dont know if they will hit anything. Anyone done this piston swap?

 

why dont you just swap the block and get it over with???a= better power b=easyer to find parts and there only like a few 100 bucks, thats what i did and my buddys crx runs around town great on 11psi boost,

 

sure, send me the money via paypal, i will be happy to swap out my block

 

Got some info you might find useful t34me. I've found the deck height on the zealautowerks calculator for D15 blocks might be incorrect. I think it might be 207.45mm. If so, by my calculations that should put PMS pistons in the hole 1.2mm, or 0.04728in. With those corrections, I found the compression using a p08 head and 0.048in thick headgasket (D15B7, D16A6) you could take compression as low as 10.02:1 (static).

 

I appreciate that info and you looking into that. The major problem lies in the fact that the GX pistons are on 2 month backorder, i certainly dont have that much time to go without a car, so i think im just going to have to settle for vitaras. Oh, and just to make sure. I like the condition of the A6 rods i posted above, but they wont fit my crank will the? Again, thanks for all your help everyone.