Turbo Choice? HY35CW or GT35(??)

Ok so first off this will be a ways off for me doing anything as the 744 is still down waiting for me to put the engine back together and then in the car.

But lets just say I found a GT35(?) Ball bearing turbo laying around here that needs a new turbine wheel. I am trying to decide of keeping my current HY35CW turbo (WG welded shut) or if I should start gathering parts to put the GT35 back together. That would mean a new turbine wheel ($120), a turbine housing $300-500 depending on how interesting I want to get. and then a new manifold ( I need to build a new manifld one of these days anyways). This would mean maybe get one of those pimp Vband Turbine housings and build a new manifold with the Vband collector. Or just go old school and go either t3 or t4 inlet. (I am leaning t4 inlet but I am odd)


So there you go, should I just keep the same manifold with the HY35CW or should I start collecting parts and money to go with the GT35?

As for goals the car last with 12.01@113 on LH with the AW71. I have never run it on MS but it for sure feels much quicker and smoother up top than the issues LH had 12.11@115 on LH with the 200r4 so on Paper ~350whp currently @ 25psi on LH. I am going to be having a head put together with larger Valves soon and my next engine is going to have rods vs being a stock block. So maybe 450whp might be a goal.

Oh and everyone loves pictures

Is there a nameplate on that "GT35," with a part number? If so, post it up.

No name plate, the turbo is fairly old, it first came into my possesion about 9-10 years ago. And at the time it already had the damaged turbine wheel as it was used on a race engine that the engine ate something which is what damaged the turbine wheel. Because of who we got it from and the age we highly doubt it is a knock off, even the local builder had doubts it was a fake. The local rebuilder said he could clip the wheel and while not ideal it would work, otherwise he could also just replace the wheel/shaft which is what I am planning on doing.

the only marking besides what you see on the front is Garrett M55 on the back of the backing plate.

Honestly, I would hands down go with the Garrett as long as the wheel sizing and exhaust side are within reason. Going from the HE341 to the 2871R, the spoolup is far better, power is pretty close, and the power capabilities of this one is around 400-450hp with the 56-trim per info I was given by someone in the know. Going with the GT35 I would expect would be a little slower but still better than the Holset.

You can also get a T3 flanged housing for it if you wanted from ATP, but if you have the time and capacity to change to something better, I'd go that route. ATP might have a wheel and stuff around as well. If you do hit them up, tell George Chris and I sent ya.

Well see the major crossroads I am at is if I want to stick with the T3 flange or move up to a T4. My plan is to move up to something like a divided T4 but use smaller runners than the normal monster 1.5" stuff, this is why I am trying to find a busted / trash 90+ manifold to cut up and see the runnner ID.

I have seen a few here use the same everything with the only change being cutting off the T3 flange and welding on a T4 flange and use a larger A/R T4 housing and they picked up spool RPM along with power.

The biggest issue is time, right now with what I currently have on my plate I will be lucky if the 744 runs again this year (it better be back together by end of the summer). But as for the new manifold and turbo setup as much as I hate my current manifold for its ability to melt plug wires I have to much other stuff I want to do on to many other cars.

So...if you're not ready to do the T4 just yet, just grab a T3 housing and be done with it. Still should spool faster anyway.

You can always get a T3-T4 adapter. I use this one with my EFR and it works great: https://www.ebay.com/itm/T3-Divided-to-T4-Divided-Turbo-Inlet-Studs-Kit-Transition-Adapter-Flange-1-2-/132028776889?hash=item1ebd8741b9

Regarding turbos discussed so far, turbine wheel diameters are:

GT28R: 54mm
HY35: 65mm (from what I can find online)
GT35R: 68mm

This is the turbine inducer or major diameter, not the exducer / outlet diameter.

Your turbo does look like a genuine old GT3582R, but I couldn't be sure without seeing it in person. But the story and photos add up.
With the non-ported shroud compressor housing you re looking at around 60 lb/min max compressor flow from the 82mm (exducer) wheel. Inducer should be 61.4mm.
Should work well for 450whp on a redblock, assuming you'll be over 550hp at the flywheel.

The larger GT35R turbine will flow more than the HY35 depending on turbine housing A/R. Lots of housing options available with a variety of inlets... T3, T3 divided, v-band, v-band divided etc.

I would not recommend clipping the turbine wheel - that is a band-aid solution at best, if there are no other options.

^^^^ might know something about the subject. lol

Whaddya think, throw a .84-ish housing on it, spool about the same or a touch faster than the HY, just more air for the spool?

You can take a large t3 flange turbo to well over 600whp.. No need to step up to the t4 unless you plan on going over 700whp..

-Sam

RoadRacer4Life said:

You can take a large t3 flange turbo to well over 600whp.. No need to step up to the t4 unless you plan on going over 700whp..

-Sam

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See I heard a rumour that you can gain torque and spool rpm by going up to the t4 turbine housing as long as things are sized accordingly.

Same idea behind people saying 3" exhaust is all you will ever need under 700whp. But even as low as 300whp you can see gains in going to a 3.5" or larger exhaust.

So it is one of those things that sure it is good enough but am I leaving power on the table by going with good enough. While I do not have huge HP goals I do enjoy trying a path sometimes less traveled.

Duder said:

Your turbo does look like a genuine old GT3582R, but I couldn't be sure without seeing it in person. But the story and photos add up.
With the non-ported shroud compressor housing you re looking at around 60 lb/min max compressor flow from the 82mm (exducer) wheel. Inducer should be 61.4mm.
Should work well for 450whp on a redblock, assuming you'll be over 550hp at the flywheel.

The larger GT35R turbine will flow more than the HY35 depending on turbine housing A/R. Lots of housing options available with a variety of inlets... T3, T3 divided, v-band, v-band divided etc.

I would not recommend clipping the turbine wheel - that is a band-aid solution at best, if there are no other options.

Click to expand...

I will get a bunch of pictures this afternoon if it helps you ID it a little better. Anything specific you want to see in the design?

Think it might be worth it to step up to a different compressor housing? What might I gain with a new housing?

Between the cost of the wheel and turbine housing I am still spending a lot less than the cost of a new GT3582R so an extra $200-300 is not the end of the world when it comes to the streched out timeline I am looking at.

I was not a fan of the clipping the turbine wheel hence why the turbo is still on the shelf.

My big reason for a new turbo is more exhaust flow as I have not been a huge fan of the smaller HY35CW turbine housing. I have been looking at lot of newer turbos but if I can make this one work for the same cost (extra benefit that it is water cooled) then I might as well not let this thing die.

thelostartof said:

See I heard a rumour that you can gain torque and spool rpm by going up to the t4 turbine housing as long as things are sized accordingly.

Same idea behind people saying 3" exhaust is all you will ever need under 700whp. But even as low as 300whp you can see gains in going to a 3.5" or larger exhaust.

So it is one of those things that sure it is good enough but am I leaving power on the table by going with good enough. While I do not have huge HP goals I do enjoy trying a path sometimes less traveled.

Click to expand...

I made 660whp on a crush bent 3inch exhaust on an old pt67 turbo.. It was a honda H22 but hey..

RoadRacer4Life said:

I made 660whp on a crush bent 3inch exhaust on an old pt67 turbo.. It was a honda H22 but hey..

Click to expand...

Yes but if you went up to a 3.5" could you of gained power? On paper 90% of TB will never need more than A 2.5" exhaust but we go larger for a reason right?

If I am building a new exhaust manifold anyways why not ?

thelostartof said:

My big reason for a new turbo is more exhaust flow as I have not been a huge fan of the smaller HY35CW turbine housing. I have been looking at lot of newer turbos but if I can make this one work for the same cost (extra benefit that it is water cooled) then I might as well not let this thing die.

Click to expand...

My hy35cw 9cm^2 seems to flow "good enough". With the 90+, stock valves and v-cam the pressure in the exhaust manifold was lower than the inlet all the way up to ~6000rpm. This was with 30-32psi on gasoline. It made 352whp, and reached 32psi by 4300rpm. So I'm sticking with it for my new low compression b230 with a goal of 400-450whp.

thelostartof said:

I will get a bunch of pictures this afternoon if it helps you ID it a little better. Anything specific you want to see in the design?

Think it might be worth it to step up to a different compressor housing? What might I gain with a new housing?

Between the cost of the wheel and turbine housing I am still spending a lot less than the cost of a new GT3582R so an extra $200-300 is not the end of the world when it comes to the streched out timeline I am looking at.

I was not a fan of the clipping the turbine wheel hence why the turbo is still on the shelf.

My big reason for a new turbo is more exhaust flow as I have not been a huge fan of the smaller HY35CW turbine housing. I have been looking at lot of newer turbos but if I can make this one work for the same cost (extra benefit that it is water cooled) then I might as well not let this thing die.

Click to expand...

Nothing specific that I'd look for really, other than a nameplate which you said isn't there. It's more of the sum of many little details that tell you whether it's genuine or a copy.

You could probably get a ported shroud compressor housing that would fit this; there was a GT3582R update before the GTX series came out, where a ported shroud housing was applied (google turbo part no's 714568-0007 thru 714568-0012). The ported shroud housing widens the map, getting you extra surge margin on the left side, and more choke flow on the right side. It could mean the difference between surging and not surging during acceleration or transients, but only above ~2.25 pressure ratio i.e. about 15 psi manifold pressure. On the choke side it would help if you were running out of steam at high engine speeds - more choke capacity means higher efficiency at high flow, since "choke" is usually defined to be 58% efficiency on Garrett maps. It would help power not fall off as soon, if your engine ends up flowing enough to be operating on the right side of the map.

Anything in the GT35R family would definitely give more turbine flow than the HY35, as long as you don't use a tiny A/R housing. I'd look at the mid or large A/R for whatever family of housings you decide on. ATP has infinity different housing options listed on their site as an example. The later GTX uses the same turbine wheel so any GTX35R turbine housing will work on your turbo, and vice-versa.

For the money id go a different route.

Been meaning to mention as well Chris, the surge issues I had on mine with the stock head are COMPLETELY gone with the big valve head, even at higher boost levels, no other changes.

Mike - if your rebuilder down that way can't do it, there's one up here in Cameron Park that's been around for days, used to build IPD's stuff. They may be able to do it a little cheaper or find a used wheel maybe. Check out Turbo Power if you get a chance. They do the rebuilds onsite and they can balance them onsite, one of the few places within a couple hundred miles of me that can.

thelostartof: I may just have a used GT35R turbine wheel that would work for you, rediscovered last night, from a "lightly crashed" Formula D car
Will send a PM.