My question is simple for those who know. How much Boost can a tII s5 engine take with no porting stock everything and also what about the turbo how much can you boost maxed out?

 

Without at least a FCD, you can't boost past 8-9 psi. For 10-12 psi, I would add at least an upgraded fuel pump, maybe a fuel controller and larger secondaries. Anything above 12 psi and the stock turbo is just blowing hot air so intake temps skyrocket = dead engine.

 

I have a similar question we have a13BTII in a Toyota SR5. The engine itself is 100% stock the only after market part under that hood is the turbo. We are using a T70 turbo with external wastegate and instead of 2mm we have 3mm seals. My question is we keep breaking the back cast iron plate right under the oil fiter where it says Mazda. We broke the back plate at 15psi, anything under 15psi is safe. We are using the stock ECU with 720P and 1600S 3inch exhaust from the turbo to the muffler.


Here are the numbers when it happened we had 720S and 720P .
oil pres 85psi
fuel 60psi
egt between 1100 and 1200
afr 11:5/11:7 top end and 12:7 idle
water temp 160
boost 15lbs

 

You're running pump gas, correct? You're running too lean IMO...I'd richen up on boost to high 10s, low 11s AFR to be safe.

 

egt between 1100 and 1200

To high....
With everything right, stock parts will take you to just over 20 psi on a 9:1 motor on pump gas..Max

 

so fuel management, injectors, will make the engine go to 20 pisi. ? is it necessary for a stand alone or is a apexi s-afc with the proper injectors do just fine ?

 

He was talking to the guy with the 13BT in the Toyota with a T70 turbo.

Do that with the stock turbo and your engine will be gone the first time you boost. Stock turbo and TMIC is good for 14 psi MAX provided you have enough fuel...and not for long periods of time because intake temps get scary REAL quick. Believe me, I know - datalogged with my Haltech.

 

Do you have a FMIC?

 

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