Just was reading some older post on s2ki and had a question about my current setup. Im currently running 14psi on my log manifold making around 390-400hp. I understand if I ran a tubular manifold at the same psi, I would gain around 50-75hp. In regards to reliability and wear on the engine, does the manifold matter? Would it be less wear on the engine if I ran a tubilar manifold at 10psi to make the same hp as log at 14psi?

In regards to the turbo size/psi and reliability, if you run a greddy kit at 15psi and run a inline pro kit at 8psi to make the same hp, does that cause the same wear on the engine. Does the HP the engine make cause it to have reliablity issues or the PSI? I always read a safe psi for a stock motor was 12-14psi, but shouldn't the type of turbo also matter in that 12-14psi? My thought was that a small greddy turbo at 12 psi should produce less strain on the engine compared to a GT35 at the same psi.

Thanks.

 

Boost pressure is just a measure of how much a restriction the motor provides. The tubular manifold is less restrictive, meaning more airflow through the motor at a given time, lowering the boost pressure.

Its not so much the boost that causes stress, but rather the cylinder pressures and temperatures. Intake temperatures will cause higher pressures, so the smaller turbo can cause more internal stress when run at the same boost level. However, the cylinder pressure isnt the most damaging factor, its temperature. The high temps can cause pre-ignition and detonation, both can tear a motor apart in a split second.

Now, to know part of the science behind boost pressure. Volume is indirectly related to the temperature and pressure of a gas. Volume goes up, pressure and temp go down. The volume isnt changing between the two turbos, but the larger will make more power. This means air is more dense with the large turbo. If volume is constant, pressure is constant, and density increases that means temperatures are down. The lower temperatures of the larger turbo will make it safer to use at a given boost level.

 

Sounds good. Going to garage the S soon and use it only on the weekends so I'll look to upgrade the manifold then. Guess should save up for a re-tune as well.