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 .

You could try finding someone with a GT30 on an RB30 and arrange a swap .

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 .

By the way that Rajab above was some sort of auto correct . Not out to offend anyone .

Bennis I re read your original post and I'll have one shot at your questions . Your asked specifically about a GTX3067R and a GTX3076R and having the same identical turbine , which they do , and the same turbine housing which is optional . Direct comparison is difficult because these two use different compressors and different compressor housings to suit the airflows they can generate . Off the top of my head the flow rates are around 47 pounds/min vs 57 pounds/min so not insignificant . These compressors are advertised as 67 and 71mm diameters but because of their extended tip blades are actually bigger than this . Also the blade count is different so 10 for the GTX67 and 11 for the GTX76 . Dimensions aside it was obviously Garretts intention to make the smallest GTX30 turbo their most responsive and a large part of that is making the compressor smaller in diameter meaning less weight or inertia for the turbine to accelerate . The compressor housing on the GTX67 is also a smaller family one so you'd think for a given wheel speed the air speed would be higher . My experience with turbochargers is that once you reach a certain point boost and airflow wise the whole engine turbo system becomes self feeding and takes off like a rocket at wide open throttle . Below this point it's quite possible to generate positive pressure at the turbo but not enough to create significant acceleration . You may think this is getting long winded but the point is I think a GTX3067R is going to reach the varooommm point a bit earlier and get into it's stride a bit sooner than a GTX3076R . I reckon the 67 would get to 15 pounds earlier engine rev wise on say an RB25 because it doesn't have the extra diameter and mass of the X76 wheel and would be spinning turbine and compressor faster as well . Feedback is slowly getting out there with the GTX3067R after what looked like little market interest in them . I think people doubted a pissy looking 67mm compressor was worth worrying about but in the right app they are shaping up fine . I'm interested to know what specific engine/car you have in mind and what sort of performance you'd like . It's difficult to make hard and fast rules with turbocharging because there are different ways to solve different issues and the fixes aren't universal . IMO with these specific two turbos the GTX3067R is a more modern and efficient GT3071R and the GTX3076R a more compact almost GT3582R with out the bigger heavier turbine . I think there is enough experience in these matters with the people here not to have to bother with thermal dynamics formulas and ditto polar moment of inertia ones . Different people try different things and eventually you have to go with what you think will suit you best . Getting a ride in someones car that has what you're considering is best provided you know every mod it has and it's tuned properly . I'm out cheers A .

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 .

Guys for the record Hazet do double ended ring spanners that are sometimes a god send for working around manifold and turbo mounting studs/nuts . I bought a set from Sydney Tools and for pulling apart the old Subie RX Turbos custom manifold and turbo system - super bitch trust me - made it quite easy . These double ended rings are offset horizontally and let you into places a normal flat ring spanner won't . The ring sections are thin walled compared to some garbage spanners and the shanks not too long . The part number for the set is 610N/8RS so have a look at them . Not cheap for what they are but if you're doing this kind of stuff all the time then time and knuckles is what you stand to save . Thoughts Scotty , cheers Adrian .

Actually I think the HKS single cast manifolds were intended for RB20s or RB26s , the cracked one in the pic above looks like an RB26 one and they were all twin outlet T4 mounting pad . The other one was twin outlet with the T3 stud pattern but the pad section is large enough to take a T4 flange and stud pattern . Original kits had a TA45S for the RB26 and AFAIK a T04E for the RB20 with an O trim turbine and a HKS unique turbine housing . Possible best case for RB25 is the HKS RB26 manifold if you can get around the different head side stud pattern . These mount the turbo back further and were intended to allow for a reasonably big compressor housing . Honestly I think the std manifold is way to go unless you have lots of thousands to throw at ideal situations . Hard to argue that a stocky with an IW GTX3071R making 330 plus wasps at the bags is average . Had its 0.82 housing had a Scotty mount 45-50mm external gate on it probably more and with mild cams more again . With a little effort an IW GT30 hides quite well under the std plumbing , Scotty inlet , and provided you weren't being a moron if the cops bust you about as standard looking as 330 plus gets to look . Affordability , manifolds free isn't it . A .

My take only . I believe the thing that separates a good system from an average one is what goes on at part throttle - on a roadie anyway . I will state that if a compressor makes it easy for the turbine to spin up readily it will . Something I used to mention is that you're not just spinning up a hunk of aluminium when your turbo "spools up" . It's attempting to pump air and the mass of the air being moved adds to the wheels weight/inertia - turbine drive power ask . As has been mentioned aero tech in the compressors makes a difference and the modern equivalents tend to be lighter and smaller in diameter . Depending on what the designer wanted wheel designs can be smaller whilst pumping more air but the spool priority comes back to the designers goals . There are obvious differences between a GTX3067R/3076R and while they use the same turbine - both the compressor and its housing is larger on the 76mm version . Also for the sort of power goal you'd expect from a GTX3076 user a larger turbine housing than a 3067 usually gets would generally be fitted so no longer apples to apples . For a given turbine size the variables are everything on the compressor side vs the turbine housing AR size and type . A .

If you find that thread there is cut/pastes of a few replies about this GT3067R on other engines like Honda S2000s and Toyota 3SGTEs . Some migrated from GT3071Rs and said they made as much or more power as the 3071R and spooled earlier . Gives the impression they are doing approximately what 2835 Pro Ss are with more efficient compressor ends . Maybe a tad more up high . Also note the Americans are pushing GTX3067Rs up into the twenties boost wise and the GTXs appear to cope with higher pressure ratios better than the GT compressors do . IF what they are saying is true it seems that the GTX wheels better suit the GT30 turbines characteristics in some cases and with the 67R do it in a T04B compressor housing . I do understand peoples reservations with a 67mm OD compressor but when you consider what a 71mm GTX compressor is capable of it shows the trend . Still a pity Garrett didn't have something between the X67 and the X71 but doubling up on turbine options would have kept the bean counters happy . Four mm and a different comp housing ups the ante 10 pounds flow wise . A .

I found a thread in the MazdaSpeedforum where someone has I think an American spec SP23 with a GTX2867R and changed to a GTX3067R . A fair bit of reading but the guts of it was that the GT30 version lost little if anything in spool and gained more top end . The Mazda was using external gating and WMI plus the user was splash blending E85 and I think their 93 PULP in a 3:9 ratio which works out to E21.25 . The power and torque numbers came up a bit over 400 each , HP and ft/lbs , and the dyno graph sort fell off at ~ 6700 revs . This fella is using a front mount intercooler and home tuning the flashable std computer and by the fuel pressures he mentions these 2.3L fours must have direct chamber injection . I'll try to post the link but if it doesn't work google Roads to a GTX3067R build . Didn't work , cheers A .

GTSS RB26 edition was a special designed to replace the standard RB26 ones so they are customised engine/car specific units . Part of what makes them work is the smaller than usual trim NS111 turbines , 62 rather than 76 trim . Once you start talking GTX2860 you get the larger 76 trim turbine standard so pointless comparing them to any GTX28 turbo . It's probably safe to say that the GTX2860R is like an updated GT2860R 63T (2530) which aren't exactly small for a sane RB26 . The big trim turbines that may give some initial lag I'd say help get around the surge issues so whilst not a perfect solution a workable one . I think that if Garrett/HKS were to do GTSSs again they would use a more modern compressor in possibly a smaller diameter . RB26s are getting long in the tooth now and there probably isn't a big enough market to justify Garrett doing anything new for them . A .

I'm interested to know how these compare to GT3076Rs and if BB centres are an option . I still think the gap is a bit wide between GTX3067R and GTX3071R and while the HTAs look good local service isn't . Tao is that comp housing a 0.70 AR T04B or T04S sized one ? Also how do those TD06SL2 turbines compare to GT30s in your opinion ? Cheers A .

If you want quiet and free flowing ring Kirawee Mufflers , my exhaust is 3.5 to 3" necking back through a 200 cel Xforce cat and the mufflers are I think Redback . The rear is 20" long and something like 6 x 11 . They can get them in 3.5" as well . It fits up very neatly and the single 3" outlet looks really conservative . A .

Yeah a while back I bought a Neo , Stag actually , fuel rail from Just Jap . I gather later RB Stags are the same as GTt rail wise ? By OE I meant unmodified standard Bosch , I was wondering if they did anything in the 5-600cc range . I'd like to see the difference spray pattern wise between their biggest standard EV14 and a modified one like an Xspurt or ID . You're probably going to say just buy a set of those , I'm just trying to explore all possibilities to get the best all round result and accurate injector control is part of that . I'd like to be able to have 15:1 petrol type cruise mixtures and to do that I reckon you need injectors with good patterns at low flow rates . 1400cc versions I've only heard mentioned once before , I thought the stainless ones were 1300cc . Latest update is that slightly more advanced timing did help the up to atmo manifold pressure and low boost torque even at sub 2000 revs . I suppose every time you take restrictions out of a turbo engines hot side you can screw more timing in at least at low boost pressures . Torque wise it's getting more like what the GTRS could do at low revs but mainly at constant loads and speeds , asking it to spin up and make power from low revs/gears and an accelerating engine is a different story . This would be the greater inertia and larger housings causing the turbine to lag behind engine revs until there is enough exhaust energy to kick it in the ribs . Anyhow I'll give it a bit more advance in the same areas and see if it continues to Improve . Injectors have to wait a bit longer $ wise ATM but that will be the next mod . A .

740 side feeds . For the record does anyone know how big the shorty EV14s get OE style ? A .

Wouldn't it be easier to buy a Manual GTt and sell your R33 ? No spanner work and R34s had lots of detail updates worth having . Styling is a personal thing and some may not like R34s . I originally wanted an R32 with R33 running gear but it was easier to buy a 33 than build an R32 GTS25T . A .

E42 (42.5) just happens to be where I can get acceptable injector control and its easy to mix . Now that the United near work has it it's easy to get . Eflex is closer to home but 50 50 with that is E35 and they charge a bit more per litre of ethanol than United does . If you try to make E42 out of Eflex you need 12 of that and 8 of 98 and it gets too easy to screw it up . I have red jerries and black ones and add one of each in the high price cycle times out of my stash , bought when the cycle is low . Fug the Oil co's .

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Much of my map has a bit more advanced timing than that one though as I mentioned I run a 50 50 mix of 98ULP and United E85 . Back in a sec ...

I gather the standard air box and snork , with a dormant Z32 , wouldn't make any difference up to 300 wheel wasps ? Intake is Scottys 80mm with a silicon step up to 100 at the comp housing . Will have a look at the timing map today to see where its at in the boost threshold area . Is anyone running a similar setup prepared to give some ballpark timing numbers in the 0-10 pounds boost 2500-3500 rev area ? A .

Yep totally agree on the 0.73 housing , HKS did them in T2 flange but no IWG . I don't hate it fellas it's just that driving in built up areas with mostly 50-70 km/h limits means getting around at sub 2800 revs much of the time . No I don't wind this thing up much because it isn't properly tuned for the 50 50 E42 splash blend it runs , if the injectors allowed it I'd probably run straight 98 pulp because it gets better at low revs and part throttle the higher the petrol content gets . I've been down to about E25 but at real low revs and pulse widths around 1-1.5ms you lose mixture control and have to raise the idle to ~ 1000 revs . This thing should be able to idle at 650-700 on PULP and with better injectors I think it will , the ViPec tries hard but the squirters get sleepy . Good injectors and tuning will get the best out of this turbo , hopefully best will be good enough in the rev ranges it spends most of its time . A .

EV14 injectors hopefully in a GTt fuel rail but spending a bit quick ATM , Lancers up for rego soon and we get bitten pretty badly for that in Sydney . I didn't get a graph for the GTRS tune and a fair bit changed since then , everything after the AFM to behind the cat grew and what's behind that flows better and is quiet . As predicted , ATM anyway , there is no comparison between the GTRS and the GT30 but that's not to say that the 30 is a laggy pig . Obviously taking some restrictions out of the system that weren't so obvious with the GT28 has helped overall and it would have been interesting to see how it would have been with a better exhaust . These 3076Rs are interesting at this point because they make an RB25 a more evenly rounded package even though they don't stick much boost it till a little before 3000 revs . I understand why people see them as being progressive over the rev rage where smaller turbos snap on and get things out of shape . I suppose if you drove around with your foot buried all the time these force you to wait a bit till they get cracking , don't think you'd get away with that for too long in these parts . My current impression is that's it's still boarder line a smidge big but not by much , if you get my meaning not really laggy but a little more shove a little lower down would be good . Don't want to open old sores but this is where a slightly lighter slightly smaller trim turbine would have paid off . The GT28 turbine was a little small where the GT30 84T is a little big and Garrett don't want to give us the lighter smaller trim 60mm NS111 turbine . Scott hinted these injectors aren't exactly high tech but that's because I'm fussy about fuel transients at small pulse widths . Fine for most people particularly with ethanol but when you want it virtually like factory or better they fall a little short . I think why the EV14s do better is because the moving parts are shorter and lighter than earlier designs and this makes them easier to control at small pulse widths .

I would look for any "quietening" restrictions in the system first , look through the back muffler for neck downs and if you can in the mid muffler . Some Jap systems use smaller sized tube from the cat to the mid muffler so an alternative middle section could work . If you want it louder makes sense to lose any restrictions it may have . A .

Went for a quick spin down to the Burg on the Princes Hwy last night and it's easier to live with noise wise , could easily drive for long distances now . The turbo transients are a bit better and the engine "comes alive" a bit more in the 2800 plus area . What is showing up is how sensitive it is to fuel mixtures at part throttle as it climbs onto boost , if its out it's not terrible but it loses a bit of torque just at the transition point . It's this that makes me think sometimes that MAF systems could be better than MAP sensed ones because the difference in air flow may give a bit more tuning sensitivity than a MAP sensor reading relatively slow pressure changes . Also I'm using manifold pressure for accel enrichment ATM and may have to go back to TP , neither is perfect . Photo wise there isn't much to see , I think the ovals are Redbacks and the rear is the largest they do in 3" from memory . You might find it a bit too quiet for your liking . I have to see Kirawee Mufflers this morning , real easy to find . If you know where Just Jap is walk down to the roundabout and look across to the left on the other side of the road can't miss it . A .