Hey i got a JDM s4 engine with the S5 turbo i want to raise the boost. What is the highest safe leve of boost can run on my car?

 

Can't really up the boost too much on the stock fuel system and ecu. If you exceed those parameters, that is the quickest way to a blown motor. Rotaries don't tolerate too much increased boost w/o increased fuel.

If someone doesn't post the info, check out the 2nd gen FAQ thread. I'm sure the info is there.

 

i would agree with gracer7 you cant bump the boost up very much without increasing fuel.. lack of fuel ***** **** up

 

what about a s5 motor with a ems? tuned properly whats the most boost you can run safly with the top mount? 12?

 

On a stock fuel system, don't run anything more than ~8psi. That's roughly the stock S5 boost level. Stock S4 boost is 5.5-6psi running off the wastegate spring. The S5 wastegate spring is the same, but they used a factory-boost controller of sorts to increase boost.

The stock TII fuel pump does not flow well at higher-than-stock pressure levels. When you increase boost, the FPR also increases fuel pressure. The stock pump doesn't like that.

Some general guidelines would be ~10 psi with a better fuel pump (walbro, FD, cosmo, supra, etc...) & ~12psi with an upgraded fuel pump, injectors and fuel control (SAFC, Rtek, standalone). The stock turbo is horribly inefficient above about 12psi, so there's no real power gain above that level. The top mount isn't the biggest concern here.

 

i would recommend bigger injectors,fuel pump and ecu