Following a rather protracted and at times frustrating experience of trying to get my car remaped to get it closer to figures it should be producing - we have discovered today that the reason for low boost is looking more likely to be a fault with the turbo.

Having replaced and swapped - wastegate actuator, boost solenoid, checked the dump valve, split hoses, leaking intercooler, seems like the only item which could be causing lack of boost above 1.0bar is the turbo (standard VF48). other mods listed below:

Supertech Pistons
Cosworth H Beam Rods
Nitrided Crank
ACL Race Bearings
Cosworth Head Gaskets
ARP Head Studs
Cosworth High Rev Valve Springs
New Valve Stem Seals
Ported and polished Heads
Top Mount Perrin Intercooler
Full Miltek 3” Turbo Back Exhaust with Sports Cat Downpipe.

Samco Red Hose Kit
HKS induction Intake kit
Stage 1 Exedy Clutch



So on the assumption that the turbo is at fault (has a crack or damage to the impeller/s), and will need to be replaced - what would be the most appropriate replacement unit to provide the following (seems a shame not to take advantage of the forged engine - but not make it unusable as a daily driver).



I would like to see 400/405BHP, without huge amounts of lag, don't want to end up going front mount intercooler or changing the clutch. The current Perrin unit is 30% bigger than the std unit and supposed to be good for 420+ (?),

the car will be used daily and only very rarely on the track so that needs to come second to drivability.

Budget is also to be considered, and clearly units range from 1000 to 2000 - so BIG difference in cost, but is the extra worth it?

Been suggested by the mapper SC36, but maybe SC40 would be better or what about MDX555-400?

Most seem to be billet now so looks like bearings are the cost differentaitors. Twin scroll seem to be very expensive, and possibly need headers to match so $$$$$...

Comments please.

 

MD321

 

md321t on mine.

 

SC42 would be what you want for approx 400bhp with minimal lag & reasonable boost.
Stick to 400 as its a 2.5 and it should last....

I'd stick on a Perrin intake hose and whilst the manifold is off add Carl Davey pheloinc spacers. Pay attention to heat management with the tmi. Fully heat wrap the downpipe, turbo flange and a decent jacket for the turbo - DEI is good. DEI also offer the gold heat reflective adhesive tape for the underside of the inter cooler ( it actually sticks well and lasts).
NB SC36 far too small ?

Good luck.

 

thanks for the comments so far -
Not sure if the MD321 is way to overkill for 400, as going above this will require all sorts of other things to be replaced as well

SC42 is on the list, would it be better tha the SC40? (whats the diff')?

Any thoughts on the Blouch Billet XTR 380 BHP (18G)?? this is good for 400 with my set up I think??