b16a2.....what pistons for what im doing?

[98b16a2]

I'm currently building a turbo'd b16a2 engine. I have it bored out to +.020. The turbo itself is a t3/t4 with the specs of a/r.50 a/r.63. I'm using a stock head with a skunk2 intake manifold and a higher flow fuel system (not sure what throttle body, fuel rail, injectors I'm using yet but there will be better ones than stock in)

I'm not sure what pistons to use. They are going to be the srp ones with eagle rods, but should I go with the 8.2:1 or the 8.0:1? Is there going to be a big difference? I'm worried about the time it'll take for the spool up on that turbo....if there is a spool a time to be worried about that is.

Thanks

 

[dtob]

I'd go with the 8.2:1 if its a street car. It will keep your off boost power a little higher than the 8.0:1. Not really by much but it will be a little better. If I was building a turboed street car I'd get with about 9.0:1 but its up to you and what you want to do. Also depends on the boost you want to run.

 

[jamesA]

I thought you were supposed to bore/hone the block to the specs of the pistons you should already have... not the other way around.

 

[98b16a2]

You can bore out to what you have but I'm still not sure what ratio I'm going with, but I am sure that I am getting SRP pistons, and I also know that they offer all of their different compression ratio pistons up to a +.020. So that's why I went ahead and got the bore out of the way, that's the constant I'm sure of.

 

[jamesA]

Build an 8.5:1-9:1 engine. it'll be semi decent if you ever have to drive the car around without the turbo (say you blow the compressor fins).

As far as the TB, buy a stock b16 one and have it bored/honed out.

 

[98b16a2]

Well, atleast I know that now. I would have figured if they said it was +.020 over, that thats what it would be. Hopefully when they are purchased, I'll take the block down with the pistons and see how close/screwed I am lol.

Thank you for the insight.

What's your power goal that you want such low compression?

Your "constant" could bite you in the ass with either excessive or inadequate piston to wall clearance. You need to buy your pistons first so your machinist can measure them with a micrometer, add the manufacturer called for p/w clearance, subtract the thickness of the hone, and bore the cylinders out that much. Rarely, if ever, will that be exactly .020". Hope is not lost, but you did just make this build harder on yourself. You'll have to go through all of the piston companies, find the specs, and see if the p/w clearance will work out. Remember that forged pistons expand due to their silica content.