I have to admit, if doing it again I would go the sports cat route. Means the car is road legal and to be fair you are hardly going to notice the difference in performance unless you are a seriously good driver.

I've just got all nostalgic there about my old motor... not missed it in the past 6 month or so until now since selling it...

 

Buy mine Mik, I've only done 100 miles since you sold yours

 

I'm amazed you haven't sold it already mate. You never use it.

I've done more miles on my Fireblade, that replaced the Impreza, in the last three months than I did in a year in my car. The novelty may wear off one day, but cars are so dull compared to bikes

Anyway, sorry for the thread hijack!

 

I have mapped an 06 STi with the std turbo, panel filter, full decat and 3 port boost solenoid to 393bhp.

Comparing different cars on different dynos (let alone some 'road dynos') on different days will only lead to chasing numbers and dissatisfaction.

Ultimately the cars will do what they do .. and I can gtee if you take the same car in a state of tune with a 'good map' on it and same fuel around the varying dyno centres, you will get a massive variance in results. Almost certainly in line with those in this thread.

 

Exactly

 

How much difference does the 3 port boost solenoid make? Hadn't thought about that!

 

On mine (when it was still relatively standard) it enabled about 0.1 bar of extra boost to be held at the top end. Becayse the 2.5 builds boost so quickly anyway there was very little difference in the build up of boost but boost control was much smoother as they are quicker to react.

 

Cheers Dunc. And you lose about 10bhp for a Sport Cat?

 

shouldn't be as much as 10bhp..

 

Back to the OP If i was you i wouldn't change anything, all you need is a custom map, and you will see anything from 330-360 bhp. If a little more noise is what your after just change the resonated section for a straight through for about £90.00 job done. if your after a bit more than 360 I'm sure the mapper can increase the boost levels but as your after a reliable car personally I wouldn't, my spec D produced 333 bhp which doesn't sound a lot but its very quick on the road and I have never felt like I needed any more power. So save some of your money and just get the map tweaked.

 

Cheers Jolly/Simon,

 

As dynamix says, rolling road numbers need to be taken with a pinch of salt to say the least. As part of the sign-off for the first 2.5 STi PPP we ran the car on several rolling roads on consecutive days on the same tank of fuel and got very varied results. On one particular dyno we got just over 300hp on the first run as the transmission and exhaust hadn't warmed up. Every run after that saw at least 5hp improvement and we gave up at 326bhp as the intercooler had started to get soaked. If you'd been having a normal rolling road session you'd have come away with the numbers from the third run which was about 312bhp and been disappointed with it. What the operator would then do is say that it needed a remap to get more power when all it actually needed was a few more runs and it would show 326bhp and you'd have been happy! As an aside note, this dyno was of the dyno dynamics type and didn't measure transmission losses. The flywheel power was based on a fixed correction factor so the numbers varied as things warmed up and cooled down. Even transmission oil spec and tyre pressures as well as tyre type can make a big difference in this case!!

The most we saw on this 'tour' was 337bhp but as we had instrumented and logged the car properly we knew that it flowed the same amount of air and fuel, the weather was almost indentical, the intake temps were the same and the individual cylinder egts were the same so the only variable was the dyno. We quoted it at 320ps to be on the safe side when we could have quoted it at 340ps quite easily.

Earlier on in the development we ran the car with the same basic exhaust spec as the 2.0 so with a proper sports cat and saw around 350-360 bhp. We did however have some concerns about it as we saw boost creep at high rpm as the wastegate got choked. Even with it running at actuator pressure (in effect the ECU in self preservation mode as it would in response to massive det) the boost crept up to over 1bar and it produced 333bhp still!

The simple solution for us was to refit the std cat and peg it back to a level that we had less concerns about engine durabilty due to uncontrolled det.



Regards

Mike

 

Is that why the 2008 PPP'd cars run a standard front cat also then Mike? To combat boost creep?

 

Amongst other reasons such as durability, noise, cost etc