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Dommo

Turbocharging the mazdafield

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Dommo

I was always torn between fitting throttle bodies, a supercharger or a turbo to the Westfield. The latter are common modifications to the MX5, but the former perhaps more suited to a Westfield. So, I went down the throttle bodies route over the winter (along with an engine rebuild) and netted myself 165-170bhp, depending on which dyno you use.

 

However, once I'd gotten an aftermarket ECU as part of the winter build, I'd gotten it into my head that this immediately makes any further changes a lot easier. I then persuaded myself that it's ok to try forced induction as I can simply put the throttle bodies on the shelf and fit a standard inlet manifold again. Whichever setup I preferred, I could sell the other.

 

I'm not the first person to turbocharge a Mazda SDV Westfield. There's at least two others, one in the states using a Mazdaspeed manifold, and one in the continent using (I think) an aftermarket interpretation of the Mazdaspeed manifold. The problem with the Mazdaspeed manifold is it sits the turbo down low, requiring modifications to the passenger side engine mount. Whilst this is out of my skillset, finding someone to do it would be pretty easy. Unfortunately, the manifolds themselves proved impossible to track down.

 

So I turned to someone on the MX5 forums who was well known for making custom turbo manifolds. I asked him if he could help me out and we started looking into the options. I gave him measurements of the engine bay and he suggested a top mount turbo would probably fit best. I then chose the turbo so that he could start mocking stuff up. I wanted a turbo that would spool quickly whilst also being readily available and cheap. This meant it was either a T25 from a 180sx or a TD04 from a Subaru. I went for the TD04 as it's slightly bigger than the T25 but should still be making positive pressure from 2-2.5k. As long as I'm sensible, it shouldn't run out of puff at higher revs.

 

Within an impressively short amount of time he'd made a mockup on a spare engine he had:

P1080541_zpsc6pfkgla.jpg

 

P1080544_zpsj5hx7wve.jpg

 

P1080545_zpssyncjxbv.jpg

 

The downpipe curves back on itself to clear the triangulation at the rear of the engine bay.

 

With the guy being 1,200 miles away, a test fit was impractical so I adopted 21st century bodgery and photoshopped it.

 

Turbo%20superimposed_zpsfjbju1pm.jpg

 

Looked close, but also looked like it would fit.

 

We put a kit together...

 

P1080598_zpsyqnrvcbc.jpg

 

And I went ahead and sourced a turbo. A TD04L-13T from an Impreza. Release the inner chav :d

 

P5280002_s_zpsug2vo3gb.jpg

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Dommo

Fast forward to today and a parcel arrives :d

 

Exhaust manifold:

P6050012_s_zpsvftwvdxx.jpg

 

Downpipe (bottom part only tacked in place as may need adjusting when rest of exhaust is made):

P6050013_s_zpsicedfaye.jpg

 

Modified actuator (essentially a bracket welded onto it and the arm extended):

P6050014_s_zpsprkqvldp.jpg

 

Coolant lines:

P6050015_s_zps0s5wqyqa.jpg

 

Turbo oil drain (can't believe I have to drill a hole in my lovely sump):

P6050016_s_zpsl9yk7a2d.jpg

 

Turbo oil feed (tees off the oil pressure sender):

P6050017_s_zpsj5s9rjql.jpg

 

and a V-band at some parts to help mock up how the exhaust link pipe will look:

P6050018_s_zpsjc1151zx.jpg

 

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Dommo

This meant I could get started this weekend and see if it would actually fit! The first thing I did was bolt the turbo to the manifold and see if the oil drain would be in the right place:

 

P6050019_s_zpsgnncyml8.jpg

 

Thankfully, it was. Of course, it was always going to be given it's the same orientation as when it was in a Subaru, but I hadn't considered that :d

 

I then double checked it all bolted together ok.

 

P6050021_s_zpsu89fyuju.jpg

 

Looks like I'll need to rotate the inlet housing, not a difficult job.

 

Downpipe also bolts on nicely:

P6050022_s_zpswcocmddg.jpg

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Dommo

Lastly for today, enthusiasm got the better of me once again and I went straight for a test fit. Here's where it all needs to live:

 

P6050025_s_zpsf3xcixb9.jpg

 

So two things in the way at the moment. The coolant pipe and the oil breather pipe. Neither are exactly rocket surgery to reroute. I drained the coolant and removed the offending pipe, followed by the exhaust.

 

P6050026_s_zpseqwjd2h2.jpg

 

Then bolted the manifold on. Some of the nuts are now a lot harder to get to and torqueing them up will be fun, but that's some pain I can save until later.

 

P6050029_s_zpsbnrzxgpb.jpg

 

The turbo was next:

 

P6050030_s_zpsnp3cayxy.jpg

 

I was surprised that even with the inlet housing at the wrong angle it still fits with room to spare. Obviously I could never get a hose onto that, but it did look like the bonnet would close at least.

 

The downpipe dropped in relatively easily:

 

P6050031_s_zpsilh4qelb.jpg

 

P6050032_s_zpss8e4v9il.jpg

 

I'll just have to move that relay box but it's otherwise better for space than I thought it would be!

 

The downpipe also currently stops in a pretty good place! Not bad when the fabricator only has a set of measurements to rely on... and I'd taken those measurements.

 

P6050033_s_zpsymdxkezg.jpg

 

In fact, the only bit of modification required is I need to file down the actuator mounting bracket slightly:

 

P6050038_s_zpsjxvrqrvw.jpg

 

As expected, the actuator means the oil breather pipe needs rerouting.

 

P6050039_s_zpsfa8qj6ud.jpg

 

In all, there's plenty of space, more than I thought they would be so I'm quite chuffed about that:

 

P6050040_s_zpsgirq6phk.jpg

 

Will hopefully get it all together by the July track day at Abingdon.

 

Cooling-wise, I think I'll opt for a RadTec radiator/intercooler combo. Expensive, but a pretty neat solution. Hopefully even with the intercooler in front of it the radiator should have the capacity to deal with all this heat.

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RussH

Nice. I previously had a turbo'd mx5 and it was ace.

You'll need to support the weight of the turbo though, the manifold will crack in 5 mins otherwise.

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Dommo

Good point. Will have to add a bracket - will the heat (and expansion) mean I need to be a bit more intelligent than just bracing it to the engine?

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RussH

I bow to the forums superior knowledge, but mine was braced against the engine.

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Dommo

Who knew image searching for 'turbo brace' would also come up with women's swimwear. That's a shame!

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KugaWestie

Good work Dom, this will be a great project to pull off!

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lewis

Great work. This is looking great!

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Kit Car Electronics

Great project! Any idea on boost pressure?

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Dommo

Finger in the air with that one. Got a figure of 12psi in my head, which should net 230+ horses. However, if it gets too close to 250bhp I'd have to turn it down. Around that figure rods start bending which means forged rods, then it ceases to become an engine you can simply replace with one from the scrap yard.

 

Standard actuator/wastegate pressure is 7psi so I'll need a solenoid to get to 12psi.

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darve

Wow just wow

My lil flowed head is gonna seem slow after this :d

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RussH

Finger in the air with that one. Got a figure of 12psi in my head, which should net 230+ horses. However, if it gets too close to 250bhp I'd have to turn it down. Around that figure rods start bending which means forged rods, then it ceases to become an engine you can simply replace with one from the scrap yard.

 

Standard actuator/wastegate pressure is 7psi so I'll need a solenoid to get to 12psi.

I ran 7psi which gave me 210bhp. 10psi+ should be fun...

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Chris Hooper

Loving the name Mazdfield

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