Subaru Enthusiasts Car Club of the Sierras - View Single Post

EQ Tuning · 2006-06-16, 10:29 PM

That response is on the ball for the most part. The only parts I don't agree with are his comments on boost. Running the same relative boost at elevation as you do at sea level will not necessarily work the turbo harder. You have to remember that this pressure is relative to atmospheric pressure. So at the same relative pressure, you're still running less absolute pressure than you would be at sea level, so you're not actually working the turbo any harder. You would be pushing less air at that relative pressure, but again that's just because you're running less absolute pressure, not because the turbo is less efficient.

We've shown this to be true empirically on Cody's car as it kept flowing more air and making significantly more torque right up to 17.5psi of relative pressure even at elevation without creating excess heat. You also don't need a helper spring to run these boost levels. The limiting factor here is not the wastegate actuator spring, but rather the stock boost control solenoid and restrictor pill. Using a 3-port solenoid, MBC, or even a smaller restrictor pill will easily allow you to run whatever boost you like without adding any helper springs.

My main question here is what boost were you hitting with the stock TMIC? If your boost levels are now significantly lower, I would deffinately look for a leak or start questioning the efficiency of the bigger TMIC.

I'm also concerned that the car seems to be making less power and had a rough power band upon ECU reset. To me this says that the ECU encountered some problem spots and had to pull timing in places where it didn't have to with the stock TMIC. Again, this could point to a leak or just a poorly designed IC.

Thanks
-- Ed

2006-06-16, 10:29 PM	#37
EQ Tuning EJ22 Join Date: Mar 2006 Posts: 132	That response is on the ball for the most part. The only parts I don't agree with are his comments on boost. Running the same relative boost at elevation as you do at sea level will not necessarily work the turbo harder. You have to remember that this pressure is relative to atmospheric pressure. So at the same relative pressure, you're still running less absolute pressure than you would be at sea level, so you're not actually working the turbo any harder. You would be pushing less air at that relative pressure, but again that's just because you're running less absolute pressure, not because the turbo is less efficient. We've shown this to be true empirically on Cody's car as it kept flowing more air and making significantly more torque right up to 17.5psi of relative pressure even at elevation without creating excess heat. You also don't need a helper spring to run these boost levels. The limiting factor here is not the wastegate actuator spring, but rather the stock boost control solenoid and restrictor pill. Using a 3-port solenoid, MBC, or even a smaller restrictor pill will easily allow you to run whatever boost you like without adding any helper springs. My main question here is what boost were you hitting with the stock TMIC? If your boost levels are now significantly lower, I would deffinately look for a leak or start questioning the efficiency of the bigger TMIC. I'm also concerned that the car seems to be making less power and had a rough power band upon ECU reset. To me this says that the ECU encountered some problem spots and had to pull timing in places where it didn't have to with the stock TMIC. Again, this could point to a leak or just a poorly designed IC. Thanks -- Ed