turboswede MegaDork
July 24, 2015 6:45 p.m.

So I picked up a Holset HY35 a while back and I was saving it for a bitchin motor in my CSX.

CSX is long gone. Working on turbonating my 924. I was going to put a tiny Mitsu TE04H on it, but the amount of dinking around with exhaust piping and the wastegate to re-clock it to get it to work seems like more work than it is ultimately worth.

So the manifold I've got has the proper mounting flange for the Holset and the Holset has a much friendlier solution for exhaust routing, wastegate, etc.

My real concern would be: Is it too big a turbo for the little 2.0L single cam motor in the 924? Exhaust manifold is a log-style unit from BAE. Stock intake, larger throttle body and a bloody huge intercooler with MegaSquirt controlling the fuel and ignition. 200-220hp would be the goal as the clutch slips much past that.

TL:DR; Holset HY35 on 2.0L SOHC. 220hp goal, up from 95hp.

Laggy mofo or not?

G_Body_Man Dork
July 24, 2015 6:50 p.m.

In reply to turboswede:

Nothing 2-step can't fix

Vigo PowerDork
July 24, 2015 7:19 p.m.

I guess it depends on how high you rev and how E36 M3ty it feels at low rpm. I think it will spool just below 4000 rpm (educated guess based on 2.2 dodge and 2.0 DSM forum reading over the years). If you shift at 5500 thats a E36 M3ty 1500 rpm powerband. If you shift at 7k it will be ok, but if your car is dog-slow until 4000 rpm it will still feel slow MOST of the time.

If it doesnt suck to drive right now and you plan to rev it high enough that it doesnt fall out of boost on every shift, i think it will be good. Defnitely overkill, but you've already got it and the packaging is easy and those are MAJOR upsides.

turboswede MegaDork
July 24, 2015 8:02 p.m.

Thanks to the larger cam and automatic timing gear (poor mans VTEC), it actually feels ok across the rev range and will rev to 6500/7000 if I want it to.

Raze UltraDork
July 24, 2015 8:55 p.m.

Welcome to the club...I've got an HY35w on the Merkur's SOHC Ford 2.3, I assume you have the single scroll exhaust housing? We have Megasquirt, big intercooler, and it is indeed laggy as hell:

If it's got an internal wastegate drill it out to 1 inch to prevent surge, otherwise it's a wild ride...

turboswede MegaDork
July 24, 2015 9:23 p.m.

Dual scroll :)

Raze UltraDork
July 24, 2015 9:36 p.m.
turboswede wrote: Dual scroll :)

Then it will be a little smoother and the overall ramp will be sooner...I will be watching with interest

chiodos Reader
July 25, 2015 12:17 a.m.

What size is the td04? That holset isn't going to make a good driver. That said I thought hy meant single scroll and hx was dual..guess I need to brush up on my holset terminology

turboswede MegaDork
July 25, 2015 12:27 a.m.

The Mitsubishi TE04H is tiny. Really sized more for a 1.5L than the 2.5L that it originally came off of.

Here's a GT40 on the left and the TE04H on the right:

I really should buy myself a welder and then I can ditch the stock exhaust outlet on the Mitsu and solve a number of problems there at once.

bgkast UberDork
July 25, 2015 12:37 a.m.

In reply to turboswede:

Nah, just bolt on the holset.

chiodos Reader
July 25, 2015 10:31 a.m.

I know how big a td04 is, ive got two, i was asking which one ie what comes after the tdo4h? Ive got a 15g currently pushing 230whp @15psi on a 200k mile 2.3 sohc and lag is not a word in its vocabulary. You stated wanting 200-220hp so the obvious answer is td04 unless you just want to spool the whole way through the powerband.

Or sell both and get a td05 14b ie dsm turbo

Jcamper Reader
July 26, 2015 11:38 p.m.

I recently sold my SVO with 2.3 and an HX-35. It drove great, a little laggy but not bad. It had a bang-bang style anti lag setup with bypass air solenoids, 120 lb-hr injectors and was running E85. The holsets really do well at higher pressure ratios, mine was set at 30psi. I think if you will be limited to low horsepower the holset is a waste of time. My two cents.

NordicSaab Reader
July 27, 2015 9:51 a.m.

I have a Hx35 (Similar size to the HY) on my DSM and am running about 40ish PSI. The turbo is a monster. I have a huge volume intake setup and manifold which is the reason for the lag.

Do remember boost is (more or less) a linear equation.

95HP*(X) =225HP(Goal)


1ATM = 14.7 PSI(Sealevel)

2.37*(1ATM) = 34.84 PSI

34.84 PSI - 1(ATM) = 20.14 PSI

So, roughly 20.14 PSI to reach goal? The holset will do that and then some, and then some, and then some more. My question is will your rotating assembly hold at that kind of pressure? Will your valve springs not float? If the answer is yes, I would go with it.

Also, one thing to know, the holset loves to boost creep. This could be a very fun and rewarding project, or it could all end with a bang... My only advise would be to find a smaller turbo. If you are set on the holset, you can real the turbo in with an external wastegate or machine a hotside off a smaller turbo to accept the holset cartridge.

turboswede MegaDork
July 27, 2015 10:00 a.m.

In reply to NordicSaab:

The bottom end of the 924 is an Audi engine that was also used as a diesel (with different pistons of course) and the factory Le Mans racer made upwards of 400hp without major issue. Its stout enough provided I don't screw up the tuning or completely fail to cool it properly (reverse cooling is required to reduce hot spots at the rear cylinders), so an electric water pump, etc. will be added this winter.

Obviously the amount of boost will provided will be slowly increased.

Raze UltraDork
July 27, 2015 11:40 a.m.

Yeah definitely higher HP applications, my MAP sensor is the limiting component in the XR4...basically 30psi, and yes I run it up there a bunch, but usually leave it around 21psi to increase clutch and trans longevity

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