[DaveC113]

Casting processes have come a long way and can offer a void-free and grain aligned structure, it is certainly possible the new pistons are MUCH stronger, but that's just as much pointless conjecture as saying the opposite considering we don't know ANYTHING AT ALL about them.

The motor knocks because it's trying to run 14+ lbs boost WITHOUT direct injection. It might be the last port-injected turbo motor on the market and it's right at it's limit. There is not motor on earth where you can just ignore detonation events and expect the motor to just take it. That's a bit ridiculous.

It is unfortunate that the motor is so sensitive to fuel, but because of it's geometry and lack of direct injection it's at a significant disadvantage. Too bad, hope 2020 works out better...

 

[DaveC113]

Eh... Run 18+ PSI on previous piston motors without direct injection and on gasoline. It's simply running too much timing.

Ok, AND meet emissions requirements. That's one thing aftermarket tuners don't have to worry so much about.

 

[DaveC113]

Subaru does high altitude drivetrain testing in Dillon Colorado. We don't have 93 octane. Considering this drivetrain isn't even used in Japan, I find it highly unlikely they're collecting data for the ECU tables and logic using Japanese fuel.

That could be part of the issue as altitude reduces the need for higher octane. 91 at 9000 ft will be different vs 91 at sea level.

In any case, yeah it does suck that the tune doesn't allow for 91 (in most cases) and the car will need to be re-tuned immediately for many folks that don't have access to 93. The car mag's measured performance is absolutely not acceptable imo.

 

[DaveC113]

Yeah, that's not hard either... Been meeting emissions requirements for years. Hell, my 550whp SHO had 2 cats on it and would pass a sniffer without them anyway.


You don't need direct injection to run 14 PSI.




The thing about a small turbo car is that the turbo runs out of efficiently quickly, as you go up in altitude. This creates lots of heat and the need for more octane.

Your assumption that passing the sniffer test is the same as meeting OEM emissions requirements may not be correct.

I never said you need DI to run 14 psi, it depends on a lot of other factors, which I'm sure you know. There's likely a reason the RA is having issues and I'd bet it boils down to lack of DI, and that if the car was DI it wouldn't be having these issues.

But that's just my guess and everyone else is just guessing too. Unfortunately, it's very unlikely Subaru is going to come on here and tell us exactly why they can't tune the RA for 91 octane successfully.

 

[DaveC113]

...

Ok. You win.

 

[DaveC113]

Lots of conjecture taken for fact, opinions formed on the basis of feelings, grass is always greener, etc. going on here imo. Nobody has statistics on the failure rate of STi motors. I'm not saying they are great and I have heard my share of folks with problems but the truth is we don't know for sure. People with bad motors are going to let everyone in the world know it, people without issues are quiet.

white RA, your insistence on keeping the car stock is ridiculous imo. I understand not wanting to do much but there are some basic and not very expensive things you could do that would yield massive bang for the buck. Using race gas and not tuning for it seems like a huge waste. Also, your intended useage of the cars seems well outside what you should expect it to handle. Running multiple sessions without adequate cool down will surely destroy the motor and you'll be on here whining about it when it'll be your fault for insisting on keeping the car stock and not improving it's cooling systems or monitoring oil temp/pressure, using a access port to datalog, etc... because that would take a modification. This isn't a ferrari or porsche, and it isn't a race car... it's meant to be an affordable rally car for the street. It doesn't seem to have adequate cooling or any ability to monitor key things like oil pressure/temp stock. A base STi is about the average price for a new car these days. Think about what you should expect vs an exotic that costs many times the price...

And selling a Subie for a Ford and expecting it to be better, lol. When your friend asks if your motor has gone out ask him if his headgasket has gone yet. There may be no good cure for that because the cylinders are too close together. All of a sudden a built EJ25 is looking good vs that mess.