fed0ra

Hey guys,

I'm pretty new to Miata's but I have some experience with turbo Audi's. I like the cost effective power and reliability that comes from a Holset, so I've been looking into that as my future turbo build. In particular I'm thinking the HX30W based on its size, the compressor map that I've seen and some anecdotal evidence of quick spool times .

Now, I know that Holset's are most efficient at higher boost levels (like 20+ psi) but would a Holset work on an NA 1.8 around 6 or 7 psi? I want to keep power levels relatively low at first until I'm able to get a new clutch and then crank it up a bit until I hit around 250whp.

So, as a temporary solution, would a Holset function well at such low boost pressures or would I be completely wasting my time?

Thanks for your help.

18psi

iTrader: (76)

There are a few here running holsets. Post specs of that specific one as I'm sure we don't all know them by heart.

If by "work" you mean "not blow up and be faster than stock" then yes I'm sure it will work. Stock clutch might not hold even at 7psi though, so might as well upgrade that right away and run 10-12 and have a whole lot more fun.

Also its not a good idea to build a setup around a turbo. It tends to get more of a pain in the butt than it seems at first.

fed0ra

Compressor: IN:49MM EX:73MM AR similar to garret 0.5AR size
Turbine: IN: 64MM EX:52MM AR: 9cm

I don't know if these are perfectly accurate as detailed Holset info is kind of hard to come across, but it should be mostly right.

Here is the compressor map: http://img.photobucket.com/albums/v2...pressorMap.jpg

I'm not really "building it around the turbo", I'm mainly just building my theoretical setup around the T3 flange. The main contenders for me, currently, are a T3/T4 50 trim with .48 AR and the HX30. I like the flexibility of the T3 flange and the abundance of turbos that use it and I like knowing that when I have more money down the line I will be able to expand to ungodly amounts of power if I so choose. I am not dead set on any of this, I'm just trying to plan everything out and price the parts before I start anything.

Depending on how much the turbo parts cost I very well may just bite the bullet and get a solid clutch from the start.

18psi

iTrader: (76)

sounds good....go on youtube and search "miata holset" there's a couple vids. I think those guys were using the hx or hy35 though. pretty solid powerband iirc

fed0ra

Yea, I've seen those videos...part of the reason I'm inspired to go the holset route. But those show him hitting like 18psi or something like that, which I wouldn't be running at first.

I have some time to think about it as I won't have the money for a turbo setup for a few months. But it doesn't hurt to research.

18psi

iTrader: (76)

well it definitely won't be nearly as fun if you're out of the efficiency plateau. Been there done that. but it should still be a hoot.

it comes down to whether you plan to build engine and run manly boost in the near future or not.

fc3s690

iTrader: (1)

I ran a 9cm2 holset hx30w for over a year. Most the holset Miata videos on YouTube are mine. Awesome turbo, but I would not suggest running it below the 18psi. When I first put that setup together I was running 7psi and I had absolutely no power. It takes a lot to get that turbo spooling, the turbine exducer is huge!

The hx30w puts out some serious torque with the boost cranked up. My stage 1 fm clutch would slip at 4-4500rpm

fed0ra

Hmm, interesting. Thanks for the input. If I stick with doing low boost initially then I'll probably wait on the holset or just scrap it altogether.

thenuge26

iTrader: (2)

That's the problem with the 'upgrade it as I can afford it' route, it is more expensive than just waiting and doing it once.

You could get a Braineack clone T3 50trim churbo but you will probably need adjustment or at least a new DP flange once you built your motor and went to the HX30.

I've seen enough people on here struggle to get their **** running right on crappy parts that I am just waiting until I can afford the baller setup.

fed0ra

Thats why right now I'm thinking the T3/T4 will be a decent route. I've seen dynos of these turbos at low boost and its a power curve I could live with. And if the lag is too much for me or if I want something more responsive then there are plenty of turbos that would be interchangeable with it.

Leafy

iTrader: (1)

If your goal is never going to be higher than 400 whp I think you'd be fine with a t2 flange setup.

But since you're going to be making your own manifold and DP to work with the Holset, why not look at subaru fitment turbos. The standard hot side fitment gets you anything from a 260hp max td04 all the way up to some crazy blouch dominator 5.0xtr that is rated for 650hp. And theoretically the only difference between the two fitment wise would be the diameter of the inlet going into compressor.

fed0ra

Well, I just said I'm probably gonna skip the holset, though it does sound like a fun project.

I might go T2 but I haven't decided. I'm used to Audi's where you can't do much without a T3 flanged turbo. A T25 tops around 300whp (at least running efficiently) and 300whp doesn't move a 3400 pound AWD wagon as quickly as you'd think.

Leafy

iTrader: (1)

My Borg Warner EFR6758, is a T2 fanged turbo, Soviet has one too and IRRC he hit 400whp on 93 and is now sorting out some fuel pressure issues and going for all the glory with e85.

fed0ra

Very, very interesting. Hmm...I will have to reconsider my plans.

Leafy

iTrader: (1)

But do note, the EFR is not a standard fit t2 and will require a different downpipe than a standard fit t2 hotside, because the hot side is longer and only comes with vband exit.

fed0ra

Yea, I know. I really wanted a twin-scroll EFR6758 for my A4. Alas, the EFR is way outside my price range.

nixapgt

iTrader: (2)

I had good time with my hy35 @8-10lbs. Standard t3 flange, only difference is the downpipe flange. Great turbo for the price, and gave me plenty of room to grow if needed..

fed0ra

What kind of power were you making at that boost? Do you have a dyno plot?

Boosted Escort

iTrader: (1)

when did you start to spool? I have a hy35 escort gt. mine made 280whp on 15lbs.