It’s a numbers game


G4, 36, 185, 362, VF28, VF30, VF37, 250,000, 1150.

Just some of the numbers from the last 4 days.

Starting with the biggest.  250,000 is about the number of kms I suspect the turbo has done.  It’s certainly the factory spec VF28 turbo, whether or not it’s previously been replaced I can’t tell though.  So I’m working on the basis that it’s the original one.
VF30 is the model that I had in the garage out of the previous car.  Usually found on a Version 7 STI.
So we pulled it off the car and had a look in the intake.  Photo below shows what we saw.

Something is not quite right

Something is not quite right

Seems like something has gone in the intake and hit the turbine and bent one of the blades.  That’ll do it.  Certainly explains the lack of performance and funny noises.  No idea what could have gone in there though.  The filter is still intact and nothing seems to be missing internally.
Oh well, time for an upgrade anyway.

A nice shiny new 36mm turbo intake restrictor got machined up and delivered to the workshop.  Hang on, that doesn’t fit the new turbo.  Whoops.  Seems the intake housing has been modified at some stage prior to me getting hold of it some year ago.  Dave goes off and rummages around his parts store and comes back with a VF37 intake housing which is essentially identical to the VF30 one.  Six bolts later and a side by side comparison, we’re good to carry on again.

I’d sent my Link G4 Storm engine computer up last week to get the header board replaced.  The header board has the plugs which connect it to the car itself and bridges those back to the ECU.  Previous one was for a four plug RS Legacy and it now needed to be a 3 plug Version 5 WRX.  Conveniently, it arrived back from Link shortly after I arrived at the workshop.

Shiny new header board on the Link

Shiny new header board on the Link

Aside from replacing the turbo and computer I have also been meaning to upgrade the fuel system with a surge tank setup.  One of the issues that Subaru’s have is the fuel tank has a hump in the middle and the fuel pump is on the right hand side. So when you turn hard right, the fuel goes to the left and the pump is left high and dry, sucking air.  That’s not good for the engine.
Solution is to have a surge tank with another pump.  So the normal pump feeds the surge tank to keep that full, then the new pump feeds the engine from the surge tank.  Simple huh?

Fuel surge tank

Fuel surge tank

As you can see below, it’s a bit complicated with the plumbing required.  But that’s why I get someone else to do it.  🙂

Surge tank with the fuel lines plumbed in

Surge tank with the fuel lines plumbed in

After finishing the plumbing and putting the engine bay back together, attention was turned back to the ECU and it was plugged in to the car and connected to the laptop.  Hmm, nothing found.  Wait, plug the USB connector into the correct slot on the board, that works better apparently.  Run through the various sensors and settings, telling the ECU what its got to play with, then load a base tune in and the moment of truth.  “Turn the key, let’s see if she fires up.”  And what do you know, after making sure the fuel system was fully primed, first start attempt and fired up first time.  Handy.  A few more checks of the software then some checking all the bits in the engine bay are as they should be still.  Uh oh, there’s a leak from the surge tank.  Out it comes again with the minor detail that it’s now full, or at least was until the hoses came off.  Took a bit of testing to figure out one of the welds hadn’t fully sealed, so some re-tigging and that seemed to fix it.

Lunch break, then off to the Dyno for tuning.  An hour or so of fiddling with fuel maps and settings to make sure it’s got enough fuel being injected at the right times so it doesn’t run lean (not enough fuel for the amount of air), doesn’t over boost and generally runs happily all through the rev range and we come up with the final numbers….
185kW at the wheels and 362nm of torque.
Happy with those given it’s running the intake restrictor.

Oh and the final number up the top, 1150 is how many kms I drove to and from Tauranga to get the work done.

Big thanks to Dave and the team at PF Automotive in Tauranga for fitting me in at relatively short notice and the awesome work on the upgrades.

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