Welcome to my world, my world of turbos, tyre smoke, and tuning...
Tuning cars, driving cars, testing parts, and complaining about everything. It's my job, and a the majority of my non-work life too...
STAV'S TECH TIPS- THE HOLSET HE221W 360BHP+ CAPABLE AND FAST SPOOLING TURBO CAN BE EASILY FITTED TO STANDARD SUBARU, VOLVO, AND SAAB, EXHAUST MANIFOLDS AND DOWNPIPES! (AND MANY MORE CARS TOO!)
Fitting an uprated turbo to a cars standard exhaust manifold is often expensive and with a pretty average result at the end of it too, especially when you have a turbo setup with oddball turbine inlet and outlet flanges and don't want to change them to custom ones to suit the new turbo.
This is especially the case with Volvos, Saabs, and Subarus (And others! Read on for that), and the typical replacement hybrid/upgrade turbos from the stock TD04 turbos are both expensive and, well, a bit of a small improvement on the whole.
Well, while researching other things and thinking about upgrades to my Impreza, I had an idea that seemed like it would work, but seemingly had never been done, so I took the punt and bought a few bits to check, and I was right, and this is exactly what this feature is all about...
THE HOLSET HE221 TURBOCHARGER...
While I've already talked about the turbo (and countless others!) in THIS MASSIVE FEATURE, let's run through the basics of the Holset HE221W turbo again.
Holset is currently the single biggest turbo manufacturer on the planet at the moment, and while their sole sales plan revolves around OEM fitment turbochargers to commercial/military/seaborne/generator/etc applications rather than the comparatively tiny aftermarket (Though they've supplied turbos to Formula One and Indy Car winning vehicles!), plenty of people have realised how good many of their turbos are, so they've become hugely popular for tuned cars too.
The Holset HE221W is one of their smaller and more compact turbos, but also one of the most impressive, and while it normally comes with the T2/T25/T28 turbo flange and a 4bolt outlet flange, it's actually very easy to retrofit exhaust housings that are the OEM Subaru, Saab, and Volvo fitment.
Capable of up to 380bhp and 3bar boost (see above compressor map) as well as super fast spool and hugely wide compressor map with massive resistance to compressor surge, it is an awesome bit of kit.
Even with a tiny rally inlet restrictor that slows spool and can make many turbo designs absolutely useless, it still works fantastically, as the datalog graph below shows.
The graph above is on a Ford Sierra Cosworth rally car with the usual 34mm inlet restrictor, comparing a Mitsubishi Evo based turbo, a hybrid Garrett T3 turbo, and 2x Holset HE221Ws, one with a cast wheel, one with an aftermarket billet wheel.
As an example of restrictors ruining the performance of what's normally a good turbo, the Evo compressor was pretty useless with both power and boost.
The Garrett was a turbo well proven as a good choice with the rally restrictor made good boost, but hit full boost over 1000rpm slower than usual.
The HE221W though, despite being a OEM production unit, made more boost than the physically bigger hybrid Garrett, and spooled 750rpm faster too.
The above is what a HE221W normally looks like with the standard turbine housing (This is just pictures I stole off Compressor Racing as I couldn't be arsed to take even more pics of the one I bought for my car- THIS is the link to the sale if you wanna buy one), and it's about GT28 in physical size, with a 60mm compressor wheel, and has something only GTX turbos of this size tends to have- An anti-surge compressor housing.
"OK! SO HOW/WHY CAN THESE BE FITTED TO SUBARUS, SAABS, VOLVOS, AND SO ON?" I HEAR YOU ASK, WELL...
The answer to this is fairly simple when you think about it, but just like the OEM Subaru, Saab, and Volvo turbos, the HE221W is actually a Mitsubishi TD04 based unit, but the Holset version is far better than all of them, it's like a 'Super' TD04.
And yes, as many of you know, while there's loads of TD04 variations of both compressor and turbine wheel sizes, the HE221W turbine wheel is actually the same overall diameter (but a better flowing design) as the 'big' TD04HL turbine wheel as fitted to the TD04HL-15T on the Saab 9-3/9-5 Aero high performance B235R engines, the TD04HL-13T on the 2.4T 5cyl Volvo engines from the C/S/V70 and similar engines, the TD04HL-15G on the 2.3T fitted to the high performance versions of the Volvo 850, and in fact many older Volvos such as certain 940 turbos with TD04HL turbos.
There's no OEM Subaru turbocharger with the TD04HL turbine wheel, but Mamba and many others sell aftermarket Subaru fitment turbine housings to fit the TD04HL for very little money- HERE is the one I bought.
As well as these, the Porsche Cayenne turbo uses TD04HL turbos, as do many Mitsubishi engines and others too.
So yes, as you've probably guessed already, you can simply swap the turbine housing over from your TD04HL, on to the HE221W, it's just one clamp, super easy, and hey presto, you have a turbo proven capable of up to 380bhp, 3bar boost, mega spool, that fits to the stock exhaust manifold and downpipe, for very little money.
This is similar to what I did on the IHI turbo on my crazy little 660cc Mira if anyone remembers that, in that case I did the same, using the factory turbine housing and after a lot of research found a much newer model car with a far bigger compressor and turbine that bolted straight to the stock housing with no machining, and the result was incredible, about twice the original power, and actually faster spool than stock too.
SO HERE'S THE CAR BY CAR DETAILS...
Hi, I'm Stav...
You may or may not have heard of me, but I've spent the last 15 years working full-time in the tuning scene, and the last decade or so writing for various car magazines.