I'm a bit of a noob to boost. Ive been doing some research and there seems to be dabate over what is most important to look at. When doing a tune people suggest not running over X PSI or X HP. I have heard both schools of thought. Im going to boost a 2000 civic Si with stock internals but I'm not very sure what to be more concerned with. Should I keep it under a certain PSI or HP or both to be reliable? Please discuss...I'm a bit confused of the subject.

 

Both, but Hp is goal one. A given ocatane of fuel can only support so much HP. Engine design (VE) also plays a role, but in the end it's the HP or attempted HP (resulting in detonation) that causes breakage. Boost pressure does play a role in that a smaller turbo will heat the charge air more (and have less volume) than desirable at higher boost pressures as compared to a larger turbo. This extra heat lowers the HP potential as well as the detonation threshold. People should really stop using using psi as a measure relating to HP. You really should say the volume in CFM or lbs. of air. Hmmm, maybe I'll rig up a flow metering device on my piping....

 

Thanks for the info. Good stuff.

 

u can use as a rule of thumb that 1 psi gains u 10 hp

normally we consider not to make over 250-300 on stock internal B series and between 200-225 on a stock D series

 

In the end detonation, torque production, and rpm's are the major limiting factors. Most people are eluding to these principles when they make blanket statements for boost and/or hp production limits.

Detonation can be caused by too much boost, too hot of intake charge, not enough octane for cylinder pressures, poor engine design.

Torque production is what bends rods if not detonating. Torque is proportional to cylinder pressures and cylinder pressures are what requires built internals.

Forces inside the engine grow exponetially with rpm's. Unbalanced and mulitiple order forces become a major enemy at higher rpm's.