New Garrett Gtx2860R / 2863R / 2867R

[KING87]

So what sort of difference would you expect to see from swapping rear housings from .64 to.86 on say a 2863? More flow in the top end but less response?

[hy_rpm]

You would only want to change to a

.86 ar if you wanted to run the turbo to its maximum

Or if the .64 is restricting the engine as the gains will be very minimal if it wasn't restricting the engine in the first place

I'm talking about 5-10kw at maximum but boost response will be down 2-300 rpm and power delivery will be later so down low power will be reduced

[NissanForLife]

If you are worried about surge issues, another thing worth considering is what BOV and pipework is fitted, is it obstructive and can it release the volume of air quickly enough as not to allow a continuation of boost pressure increase?
Is your inter-cooler restrictive and associated pipework?
Is any in-let pipework on the pressure side restrictive? especially when someone has a great exhaust set-up that promotes very efficient spooling in the turbine side, this creates an efficiency differential that than can create surge issues, and this is why every car can be different.
Anti Surge compressor housings are a bit of a band-aid solution for a system that is not balanced in it's flow on each side of the turbo and I believe trying to eliminate these issues at the core is paramount in achieving an anti surge turbo setup. I know some big turbo set-ups are much more prone to this that others, but to simply only rely on anti surge housings is not the only way to solve these issues.
I know a-lot of people rave about the stock BOV's on GTR's and so do I, but have they reach a poor efficiency point with these new GTX turbo's? It seems that partial throttle surging can be where it is noticed the most? Is this a sweet spot of Turbo efficiency vs a poorly operating BOV setup? I know the mid range on these new GTX range is brilliant especially the 2863's is this where the surge is being seen, in the mid throttle range on partial throttle openings because this would make a lot of sense for some cars.

One thing I think about when considering this setup is to definitely keep the rear housing from the -5 in it's unmodified form, as to not increase the efficiencies of the turbine side, this could be making the flow differential issue in surge be seen at high RPM's vs low RPMS ?
if the .86 housing was used then would we see the surge more up in the high RPM's?

Anyway these are some the things I have been thinking about, even though I don't even own my GTR anymore...........lol.
Funny how I can't stop playing cars without one.............lol.

[discopotato03]

I don't know that there ever was a compact RB26 style GT28 0.86 AR turbine housing made . There is the normal SR CA style one in low temp spec material but some people don't like the effect they give with the 76T GT28 turbine .

You could be looking at a fair bit of extra lag if you had two on an RB26 because that a reasonable AR size change for the 1285cc firing into each turbine housing . Not quite the same thing with a single turbocharger .

A .

[NissanForLife]

I would be very careful about swapping the rear housings from the -5's when doing the GTX core drop in upgrade.
I noticed that the GTX2863 drop in core to the dash 5 was exactly what the -5 needed to make it a very responsive large turbo, changing to a larger rear housing is not necessarily the right thing to do, I achieved 478kw @ the wheels with great response and was very happy with my set-up. All done with housing and rear remained the same straight off the -5.
31 psi was perfect for this set-up and could even go to 33 psi, but was starting to show signs of dropping off with small power increase.

[discopotato03]

I don't exactly go with the business of using compressor recirc (bovs) to combat surge . It's hard to imagine controlling air flow with them other than at closed throttle which is their intention . I think more "mid range" with these GTX turbos involves higher rotating group speed in these engine rev ranges and these turbos were designed to have port shrouded compressor housings . Once you remove them you're outside Garretts specs and on your own in the surge department .

May be hard to swallow but IMO these GTX28 series turbos are intended for single apps and not something intended to be used two up on RB26s .

I cant remember if I mentioned it before but one long shot may be to do what Nissan did with compressor housings on RB25DETs . They have a groove machined that from memory lines up with the tips of the higher blades and I think this may have been to act a bit like a ported shroud . It's something someone could try but don't come back at me if it doesn't work because I'm just pointing out what an OEM did in a different application .

A .

[scotty nm35]

Yes disco, even the later M35 Stagea ran that surge groove in line with the top blade tips. Must have worked well for Garrett to continue using it.

It isn't hard to machine in either, but I am not sure it will combat full throttle surge.

[discopotato03]

If people are really determined they can try to machine up some kind of port shroud boss and press or weld them into RB26 style compressor housings . HKS went to a bit of trouble to make a compact port shrouded housing for the single type GTRS . If someones prepared to make up bosses and inlet piping to suit it may fly but it could be considerable work for zip too . Obviously the problem is that a standard config 26 TT system was made compact and is difficult to work on as is . Finding space is not going to be easy or make working on it any easier . Is there any oxygen in making new manifolds that space the turbos a little further apart ?

Nothing is going to be easy or cheap in this area IMO .

Can FP do better than cast wheels that don't surge in plain comp housings ?

A .

[Piggaz]

I believe FP have a 68 mm wheel that can be used in these housings. Be a bit big I reckon.

[Roy]

So cant anyone really speak to whether GTS2860 with proper 3" anti surge cover will outperform std -5s ? Going to be a 2.8L with baby 260cams, std exhaust manifolds and .64 IWG rear housings

Thinking I might try the 49 trim vs 58trim just so that the turbos come one nice and early and torque curve a little flatter to help little 265 rear tyres out a tad

Want more than GT-SS but dont need as much as -5s. Other option is low mount single but point of new engine is will pass the "pop the bonnet test" for next few years so low mount twins easier to get away with

[shombre]

Sorry for the late replies, I don't really check this forum regularly.

Got a before and after graph for us to look at?

Yep, as attached. A couple of things to bear in mind - as soon as we put the car on and saw what gate pressure alone yielded, Trent and I made the decision to do all subsequent runs in 4th gear and with a faster ramp rate than the comparison graph. I didn't see the need to flog the motor any more than I needed to when the numbers were already great. The tradeoff is that the graph looks very laggy in comparison to the 2860RS one. In fact on the street, without any brake boosting or other trickery, it reaches 22psi at ~3800rpm in 4th. For a genuine 500+rwkW car on normal fuel, that's pretty damn good, and about 600rpm better than my 2860RSs were doing for ~10% less power at 24psi.

BTW, this result is with a 2deg timing buffer It made over 550rwkW but like I said, daily driven on regular petrol, so safety and reliability held primacy.

Engine details? Would help us to make a comparison...

Hi, yes it would. The most relevant details are ~3.3L displacement 2JZ GTE stroker motor, +1mm Ferrea valvetrain, stock throttle body and inlet manifold, GSC "S1" cams (269deg/9.9mm) through a 6 speed drivetrain. Without boring you with a spec sheet, it's (heavily over)built for 9000rpm and 1500rwhp. I have an appropriately conservative 7300rpm rev limit and cam gears dialled for maximum street friendliness rather than peak power.

Hence my point that it can't be compared directly to anybody else's setup on here, rather serving only as an interesting data point. It really is a badass street setup. Lots of easy power without revving the goolies off it, as Chris Harris so eloquently put it once.

Were you running the same .86 tial housing with the gt2860rs as if not there will abit of the power gain and that's why more ignition timing could be added

Yes, I was.

Edited May 10, 2014 by shombre

[NissanForLife]

Gee I think for circuit work you would want restrict the power delivery to be more linear and I didn't think I would ever say that.
The power increase is far to rapid for my liking, although easily fixed and controlled, so job well done.

[shombre]

Gee I think for circuit work you would want restrict the power delivery to be more linear and I didn't think I would ever say that.

The power increase is far to rapid for my liking, although easily fixed and controlled, so job well done.

Thanks for the kind words, Simon That was my initial worry but in fact on the street it's deceptively linear. There's no question that it gives my RaceLogic traction control a workout, especially in the wet, but it's a lot of fun.

[Piggaz]

So cant anyone really speak to whether GTS2860 with proper 3" anti surge cover will outperform std -5s ? Going to be a 2.8L with baby 260cams, std exhaust manifolds and .64 IWG rear housings

Thinking I might try the 49 trim vs 58trim just so that the turbos come one nice and early and torque curve a little flatter to help little 265 rear tyres out a tad

Want more than GT-SS but dont need as much as -5s. Other option is low mount single but point of new engine is will pass the "pop the bonnet test" for next few years so low mount twins easier to get away with

You putting a stroked 26 into your gtst?

[Roy]

Yeh...getting pulled I over too much these days and so far so good but going for street legal club car so I can enjoy the next 15 years of ownership as much as the past 15 years.

Also road trip to Spa, Zandvoort etc next year so need some reliable grunt to be quicker than the calibre of cars at European track days.

Lol...hopefully Racepace power can beat 458/991 GT3 race car power

[Ants]

Your taking the R all the way to Spa next year???

[acsplit]

You and Paul love talking about your cars but I don't see any racing!

[Piggaz]

You and Paul love talking about your cars but I don't see any racing!

Shh you. Saving monies for gearboxes.

[acsplit]

And Roy my setup looks standard

[KING87]

GCG are releasing a .86 compact stainless housing for the RB26 later this year (Sept - Oct) but just sticking with the -5 ones might be the go.

I will be using the 2863 with the anti surge housings easy enough to change a few pipes around.