Jump to content
SAU Community

Recommended Posts

This has been nagging at me a bit. Apparently Garrett's created a T3, twinscroll 0.61 A/R housing that would presumably go on something like a GTX3067. It seems faaairly undersized (understatement) and makes me wonder what Garrett had in mind.

What would its characteristics be like in comparison to a T28 turbine with the .64 a/r housing? Twin scroll aside. I'm not sure how to calculate which housing is actually bigger given the difference of T2/T3 and single/twin scroll, but my guesstimate is that the .61 is actually smaller.

Edited by Skepticism

A few things to consider

Firstly the turbo (turbine housing) has to fit your manifold/engine so John West any that don't .

Secondly Garrett do use the same turbine housing castings at times for a few different sized turbines ie up until recently GT30 and GT35 turbines in differently profiled common housings .

Mostly GT28 turbine sized turbos don't bolt up to RB manifolds unless they are unique HKS hybrid housings with T3 flanges , Garrett pretty much used T2 flanges on GT28 turbos/housings .

Garrett is obviously making a range of turbine housing ARs to give users a bit of flexibility with different capacity engines . For example if you had a 13-1600cc engine and you wanted to use a TS housing then 0.61AR probably isn't unreasonable . You'd think its small for a 2-2.5L engines but even so on a low revving diseasel application maybe fine . For petrol a bit small IMO .

Most people agree that comparing single and twin scroll ARs is a head flick , the whole point of twin scrolls is to halve the number of exhaust "putts" into each side to make the engine scavange better and reduce exhaust reversion .

I believe that when the engines loaded up and high in its rev range the total flow capacity of the turbine/housing combination is more important and the overlapping exhaust pulses get so close together that the TS advantage tapers off .

In the heavy duty engine world , most big automotive diesels , the housings are sized to give the best performance and efficiencies under full load because that's where they spend much of their time .

Different with a road car engine because you mostly can't use its performance potential for more than short bursts and stay legal speed wise . In some ways having a wide rev range shows up the limitations of centrifugal turbochargers because its difficult to make them work effectively across the whole speed range of your average petrol engine .

Twin scroll turbocharging adds another dimension of complexity (manifold/turbine housing/wastegating) but done properly can help widen the forced engines power range over single scroll setups . I believe done properly it achieves this by improving the engines performance off boost and allows better efficiencies up high if the turbine/housing/gates are sized to suit the users top end wants . Everybody's wants are different so each has to define from the outset close to what they want to achieve .

Personally I think GT28 gear is a tad limiting for any single turbo RB except maybe a mild RB20 , twins and 26s are a different story . I think you can do better for an RB25 and we'll soon know if the 0.63AR single scroll housing on a GTX3067R is responsive enough for even a conservative RB25 .

I have read that Garrett wants to do larger AR housings for GT28 turbos but I reckon there are limits to how high a capacity compressor a GT28 turbine can drive regardless of how big the 28 housing gets . People reckon the 56T 71mm GT compressor was getting laggy with the 28 turbine and I don't think the situation gets much if any better with the GTX67 or GTX71mm compressors .

Borg Warner has shown that turbines can get larger in relation to compressors if they have less mass/inertia but that means using expensive exotic materials and Garrett doesn't seem to be interested in going there .

Hope this helps cheers A .

Thanks for the answer disco

Bear in mind that I've got an SR20 - I just thought SAU would be the more interesting place to post this as I've seen a lot of in depth discussion on turbos :)

Upsizing the turbine wheel seems interesting for SRs though, as going for the large T28 housings is a generally a waste of time. Maybe because unlike RBs, SRs make most of their torque in the mid range and fall off quickly, so need a bunch of timing up top to make power - so maybe the SR head limits things and breathing isn't such a huge priority. With bigger housings there's still a power increase, but with substantially worse lag and boost threshhold. Conventional wisdom is that a bigger comp wheel on the same housing will yield similar power with better transient results. Nobody has ever really tested a really small A/R with a bigger wheel before though. I have no idea what would happen. I guess that's my main question.

Edited by Skepticism

I haven't yet seen the 63 3067R results so busy ATM .

All I know about SR heads these days is low port high port - and a little about the GTiR variation .

What I do know is that sometimes using a lower max flow compressor for a given turbine size can give good results especially with low to mid range power in mind . I believe it comes back to having equal pressures across the cylinder head (inlet and exhaust) when running in the most useful part of the rev range .

Gotta run cheers A .

Some examples of lower capacity compressors were done by Mitsubishi but in some model Garretts you have a choice of trim sizes , you don't always have to go for the highest capacity one . In their later models you don't get too much say but there is a large range with small jumps for the GT28 series using GT or GTX compressors .

Slowly more pics and details are filtering out on the GTW turbos and I have a bad feeling that they are larger BB and plain bearing cartridges going off the pics . The larger centre section looks like the one used in the BB T04/60-1 and T04Z units . The turbine dimensions look like (from memory) T04 in N o and P trims and the smaller ones some other T series offering .

The compressor backplate looks like machined aluminium not the ring type adapters used in GT25 based BB cartridges ie GT2554R - to GT3582R .

The 9 bladed billet compressors are a step in the right direction and lets hope they make similar things available for the GT30 and GT35 based BB turbos .

Where abouts is the results of the 0.63 AR GTX3067R ?

A .

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I've heard the Tomei USA head gaskets are decent if you want to o-ring the heads but otherwise not recommended.
    • The 296mm rotors are the R33 turbo brakes. The 310mm rotors are the R34 turbo brakes. The calipers are nearly the same, but not. They're the same caliper but the R34 caliper has longer legs so that it sits out far enough to go over the rotor. The pads are the same for both. When you say, "I bough tsome EBC"....did you just mean pads? Or rotors? 310mm rotors fit under 17" wheels. There may be some wheels without enough clearance though. I can't fit my fingers between the barrel of my wheel and the "corners" of my R34 calipers, but there is plenty of room behind the spokes. This is on Enkei RPF1. You can fit 324mm rotors inside a 17" wheel, but I'd be willing to bet that it would be close to impossible with the Nissan/Sumitomo caliper (using an adapter, of course), because the Sumitomo caliper is fatter than the Brembo caliper that is supposed to go on the 324mm rotors.
    • Hi. Can someone tell me what brakes(and mainly WHERE) can i buy brakes on R34 GTT? I bought some EBC which SHOULD go on my car(i have GT but it has GTT brakes) but it does not fit, Brakes are "too" small(296mm) Are 310mm be good or? I have 17 inch wheel so no "big boys" but for me driving i just need one that fits and i can get here in EU/Czech.
    • Since winter isn't that harsh anymore in Poland, i will definetely drive it 365 days a year 😉. But if the snow hits i will try it for sure and let U know. Only swap i am planning to do is of course R34 GTR front 😍.
    • Hey. Very valuable information about pitwork, I will pay attention when buying any consumable parts 🙏 As for the carpets - I got a handful of information from nengun, from which it appears that indeed the carpets for the driver's side are OEM. They are not able to show me any pictures due to the long chain of different sales entities but after I place the order, as soon as the goods arrive at the nengun warehouse from which they will send the shipment to me they can send me photos and if my purchase differs from OEM I can immediately return it / cancel the purchase. I think I will give it a try 😉. Of course i'll let you know what's what as soon as i get them P.s. I know the topic is not relevant to the thread, but both nengun and amayama have these SICK 😍 trunk room lamps available. Do you know anyone who ordered them? I need to have one in my car
×
×
  • Create New...