i have an 89 civic with the same motor d15b2... from what i have gatherd online and from my honda buds only about 8 psi is safe on that motor bone stock for a daily. Any higher and you are flirting with disaster.

The rods are like tooth picks! lol and it is probably still dpfi (dual point fuel injection) not the best for a turbo setup imo. would have to convert it to mpfi (multi point fuel injection)

if its a fun motor then boost it untill it pops! if its meant for a daily, i personally, would stay around 6 psi....

oh and good luck finding aftermarket rods, pistons, hell anything... brian crower sells rods for your first born.. lol

hope i helped good luck!

 

boost isn't boost.... you can't just up and say "any more than 8 psi blah blah blah... " - Destroying an engine comes down to cylinder pressure, which has nothing to do with the boost pressure you're running. There are a whole sh*tload of factors that play into it, but the net result is find out what your engine can handle in power.

A small turbo running high boost will net you the same power output as a big turbo running low boost.

Take my car for example. I had a small 16g (tiny turbo) and ran 10psi daily. Very reliable, but i only netted roughly 250whp. T3/T4's on the same engine at 7psi are making up to 300whp.

 

the reason why you made less power on your 16g compared to your t3/t4 can be a number of factors. the first that comes to mind is higher pressure, higher heat. hotter air charge will create less power. tuning factors. turbo efficiency. the smaller turbo is not efficient at high rpm so hp will be sacrificed. smaller turbos are efficient at lower rpm which creates more torque. a larger turbo is more efficient at higher rpm which will create more hp.
pressure is a factor of volume. if the engine uses 200 cfm at high rpm and your turbo is pushing 400 cfm pressure is created. 10 lbs of boost is a specific amount of cfm over what the engine can use. a larger turbo will just get there quicker and a smaller turbo will take longer to get to that point. using a different turbo doesnt change the fact that an engine will create boost based on volume.

if a small turbo is generating 400 cfm and a large turbo is generating 400cfm on an engine that only uses 200 cfm then the boost pressure will be the same....