discopotato03

As fas as I know they were a consumable assembly and not that people do but replaced with new . No spares available and difficult to keep the ceramic turbine on the steel shaft when trying to gut them . Its not a case of not wanting to be wasteful but by the same token very few water pumps get rebuilt for the same reasons . A .

Good to see some vertical tube intercooler designs creeping in . Of late I have seen heaps of motorbike radiators with curved cores and that would be a great way not to have to cut anything in the nose of the car if intercooler cores were the same . I still like the Trust unit shown above in the R34 and I reckon when enough of the current wave of turbo diesel intercoolers are available through wreckers they would be a good start for fabricators . Upwards of 300 Kw potential in a standardish looking engine bay isn't too shabby . A .

I've recently bough a couple of second hand Hitachi alternators , one from Pick and Payless - 1990 300ZX LR180 (80a)$50 , and one from Pick a Part Dapto - 1995 A32 Maxima LR1110-705 (110a) $35 . The first owed me $54 for bearings and works fine on the old Subaru , the second $63 for bearings and with a bit of stuffing around will be for my S2 GTS25T . The Skyline has its original Mitsubishi 80a alternator and its plug is different to the Maximas Hitachi one . I have the Hitachis plug and sub loom so assuming it fits up ok the wiring should be straightforward . I'd be interested to see the adapter provided with the above Bosch alternator if anyone has a pic . Something like that would make it easy to splice together an adapter wire to save cutting up the original loom . That aside researching higher output alternators shows that they make higher output even at lower revs than some cars std alternators . Going from a 50 to an 80 on the old Roo showed no voltage drop at idle (14.3-14.5) and the headlights don't dim at idle anymore . It probably doesn't hurt to have this kind of voltage or similar at the coil or pump either . Generally luxobarges get the highest output alternators because they have that much electric BS in them and the trendsetters want all that operating in quiet cars and when idling at the lights . Anyhow I'll get back when its in and running , cheers A .

It would be an interesting experiment if someone had the cash to blow but most people want higher power numbers for the dollar outlay . Most people don't buy GTRs to have good smooth timely power delivery thats accessable most of the time . There seems to be this can't have less than 350-400Kw in a cult car - no matter how Camry like it is at urban speeds . Personally I think if someone came up with a turbo that turned an RB26 into a broad ranging torque monster it would make a lot of owners happy in their street GTRs . Its not to say that a twin scroll twin integral gate GT/GTX30"76"R is the best one for the job but with the right compressor housing it may well be a good sane upgrade compared to the factory standard twins . The bottom line is its not easy to persuade 2568 low CR ccs to haul 1500 odd kgs around in style . They need boost to make torque because the engines capacity is not enough to do it well on its own . In this day and age you'd think Nissan would use better chamber and piston crown designs so they could increase the compression ratio and gain better part throttle torque . They'd also use infinitely variable cam timing both sides to increase the cylinders trapping efficiency at low revs . The hardest message to get across to people I reckon is that Nissan did not have any intention of making the RB26 a good all round road car engine . It was an engine they used to homologate GTRs for production based circuit racing and the capacity was based on a class weight limit formula . Plainly its not hard to make a lot of power from an engine of limited capacity but to do it from the sorts of revs road cars typically use it takes all the "smarts" - and RB26s don't have a lot of them . Its an engine that makes power at revs and its unreasonable to expect any even reasonably conventional turbocharger to change that . Smaller ones will boost earlier than larger ones but they start to limit the top end then . Nothing is cheap with a GTR I think because they stuffed a lot of stuff into a car with limited space they are very time consuming cars to work on . Lots of things could have made them better and none of them is cheap or easy . Things like VCT/more capacity/shorter diffs/different turbos - all big bucks . Anyway on topic a single TS turbocharger with some kind of integral wastegating would be simpler than the factory twins and possibly work over a wider range . Still not a complete fix for an engine that wants to haul between 3500-7500+ but you can't have everything . A .

I may have had a win with this . I stumbled across a 95 A32 Maxima (VQ30DE) in a wrecker and surprise surprise it had a Hitachi LR1110-705 (110a) alternator on it . They take a bit of digging to remove , hate transverse V6 front wheel drives , but at least when you remove them yourself you get all the fasteners and plugs etc . I'm not sure if it will be a direct fit to my GTS25T but I think it will be close enough to go in without too much of a fight . The cars ODO showed 196K and the badly cracked rad top tank is most likely what killed that car . Myself and a mechanic friend freshened up a 2nd hand Z32 300ZX Hitachi alternator for the old Subaru and the upgrade from 50 to 80a output was good - no dim lights at idle . This Maxima alt owes me a whole $35 and the other one cost $50 and a pair of bearings . I'll get this one tested and if good we'll split it and replace its bearings - and brushes if required . More later , cheers A . BTW - be wary of old plastic top rad tanks because they can go without warning and damage engines easily . I say the top one because the hot side tanks are always the ones that cop the hottest coolant and generally die first .

Those above Perrin links are a good read . That fella clearly shows how turbine side flow has a big bearing on how the turbo and the engine turbo combination works . Slightly OT but I am curious to know if the Garrett Evo 10 twin scroll twin gate GT30 turbine housing would have worked better on a flat four with their screwy firing order and generally single scroll header layout . Garrett do from memory 0.73 and 0.94 AR versions of that TS turbine housing . Anyway he is at least looking for a reasonable spread of power even if its peaky on the graphs and the peak at ~ 4500 revs has to be better than one around 6000 . I'm also pleased that he takes some effort to show that these GTX compressor wheels work better at higher pressure ratios (boost pressures) and thats well and good if you want to run high pressures and your engine can stand up to the higher power loads - without bending rods or killing big end bearings . Generally speaking it looks like in your typical 1-1.2 bar (15-18 lb)range the gains are minimul though the compressor OD changes are significant . They should really be calling them GTX 3073R/3078R/3585R and while it won't happen it would have been interesting to see what the wheel performances were had the ODs been the same . I think broadly speaking they are working on the big trim GT turbines being able to support higher power outputs and finding ways of achieving it without using big compressor OD differences . Those side compressor pics show differences that may not seem big at first glance . Take another look at where the jamb nut is and compare the hub diameter of the GT and GTX wheels size for size . The hub diameter of the GTX wheel is a fair bit smaller and where their isn't hub pork theres blade available to churn air . This was pointed out to me a while back by Mark of GT Pumps when comparing FP HTA wheels to Mitsubishi TD05 ones . Anyway the older Garrett GT wheels in the small frame GT BB turbos are lifted from the GT diesel turbo range and given a small bore hole to suit the smaller BB GT turbines shaft . Those GT wheels were intended to be threaded bore wheels and they have a hexagon cast into them so they can be tightened onto the diesel turbos bigger shaft . You can see the remains of this hexagon where its been mostly machined away so that they fit on the shorter smaller diameter BB turbine shaft leaving room for a seperate nut . At the moment my interest in these Garrett turbos is with the smaller GT28 turbine based versions because they have the potential to suit small 1600-2L ish engines or in twin form on guess what . I did some reading recently on the GTX2863R and 2867R versions and the maps look like they have potential . Slowly more info is getting out about the GTX2860R and I wouldn't be surprised if it gets down into the 54-56mm OD compressor turbos with the GT20/22/25 turbine sizes . It seems the future is small engines that rev and can take higher boost pressures to make acceptable torque , high pressure diesels are here now . Anyway compared to years ago we are getting better compressors and a reasonable range of IW turbos , still room for improvement with turbines and hopefully more TS TIW turbine housings to broaden the boost range across the engines usefull rev range . It remains to be seen if variable area turbine nozzle housings will get popular or just the manufacturing "ease" of casting TS housings be the economic answer Interesting times , A .

The story I'm getting from exhaust people is that those metal cats don't look remotely like any OE or aftermarket replacement and that its up to the vehicles owner to prove the emissions are legal . I think 99% of the time that if a cop or RTA inspector goes looking and finds what looks like a conventional cat and the exhaust doesn't smell acrid they'd be happy . I'm sure these larger body and matrix area ceramic cats are no major issue for the 220-230 Kw I'd like from my Evo and I don't think they are real dear to buy . A .

Using aftermarket fittings can work but I prefer to use second hand OE fittings particularly with water lines . Its a case of finding banjos with enough length of steel pipe to get far enough away from the turbos heat to connect to existing engine side pipes with good quality EFI hose and fuel line clamps . Cut splice clamp done . I always found aftermarket to be bulky and looking out of place - and EXPENSIVE . When I was using T3 based hybrids on FJ20's I used the existing oil fittings and had threaded unions (weld on -4 AN ones from memory)brazed onto the oil lines tube and used braided lines from there . All this screwing around is a PITA and at times costly , you waive all this if you opt to use units like GCGs Hi flows because packaging wise its a std turbocharger . Personally I would have looked at simpler alternatives like say an RB25s Hitachi turbo or possibly a good used 2530 or GTRS kit .

R32/33/34 hitachi turbos are actually easy physically to Hi flow because the compressor housing (not necessarily the comp wheel , fit on a Garrett t3 comp housing backplate - the aluminium thing with the radial ribs on it . Hitachi Turbine housings with a bit of machining fit the Garrett T3 bearing housing as well . So what I think you have is a Garrett water cooled bearing housing or center section if you like with who knows what turbine and compressor wheel either side . Those Garrett center sections are like a Mecano set in that a huge range of turbines and compressor wheels can be used with them . The downside is that many are thrown together with innappropriate wheels purely because - yep you can . Its the reason why so many bastard hybrid turbos don't work very well , the builder or user often doesn't know what works well wheel wise and or housing wise for a given application . I find Hi flow turbos with std housings can work , at times , with slightly larger wheels with fewer blades but thats a very broad generalisation . Larger compressors often want port shrouded housings because higher flowing wheels want to feed more air than the engine can swallow so you get surge . BTW your compressor housing looks like R32 GTST , the RB25 and VG30 BB ones are larger and have Nissan Motor cast into them in bold letters . Cheers A .

My opinion is that you need to get some boost in reasonably early if you want it to pull hard without revving to the moon . I believe its more about torque than Kws but thats me . Don't write off the GT2860R units like GT2860RSs and "GT2530" turbos . The 2530 can be an easy way to get a direct fit HKS turbine housing which also works with the GT2871R cartridges - same turbine wheel . The thing is that you need a turbine housing sized to make the turbo boost where YOU want it to in the engines rev range but often that makes the compressor end want to surege - ifs its early which is good . The fix for that is port shrouded compressor housings and the nous not to go too big in compressor trim size . The HKS GTRS (GT2871R 52T) is a good example to look at because they used a direct fit 0.64 AR turbine housing and a port shrouded compressor housing . From memory HKS also did a KAI version of the GT2530 and I think the difference is the port shrouded compressor housing . Ported comp housings are good things but they are only designed to work with one size and trim of compressor wheel - its about placing the surge slot at the right height to suit the wheels splitter (lower height) blades leading edges . Anyhow your call , I'd be conservative because I'd prefer have the use of the turbo most of the time rather than occassionally . A .

With anything that is machined or fabricated there is a cost factor involved - no one makes these things and gives them away so there will be some compromises . The very best manifold in the world could look like a POS but be functionalal and reliable . I know it sounds dodgy but there is such a thing as good enough and making it nice to look at gives the impression of good workmanship but doesn't necessarily make the result any different . If a good fabricator was going to make a manifold for personal use and their time was their own they'd go to the extra effort . The trouble is customers want minimum cost and that means minimising time (labour) to make it happen . I would be more interested in function and reliability , cost too , because you can't see the bloody thing when you're driving it and one would hope you bought it to use it rather than look at it . As was mentioned exhaust manifold braces can be VERY important and they weren't put on the race GTRs for looks . If you can support a manifold I believe you can get away with lighter possibly) less material because you dont need as much structural rigidity merely holding up the mass of the outer half of the manifold and turbocharger . Possibly OT but steel bridge structures are a good example of how things designed to work in tension (or compression at times) can be light strong and long term reliable too . Provided the braces have some freedom of movement they shouldn't crack . My 2c , cheers A .

They don't look like anything OE and I reckon if you'd done and emissions test it wouldn't pass . I searched and eventually found what I was looking for which is a Catco 8007 . Big bastard at 7 point something litres and I thing 16 inches long . I think I remember the one on my R33 barely fitting between its direct fit flanges so if its can volume and biscuit frontal area are larger it should have less resistance to exhaust flow . This is not where I found it , that was Sumit Racing , but if you scrol down to the cutaway pics on the left hand side you can see the differences . http://www.catco.com.au/products.htm Cheers A .

Hi all , before I start I am NOT looking for cylindrical metal cored cats so please don't go there . I have been searching for ceramic cat converters because I want a 3" one with a coated ceramic matrix . I want it to look like a cat because it IS a cat and it isn't needed for mega power - about 230-250 wheel Kw . My GTS25T has had one for years and when I bought it there were two sizes of body basically big and small . The big one had a wider "biscuit" and would have been the higher flowing one of the two . I can't remember but it may have been a Catco . Can anyone in the know point me towards the big style of oval ceramic cat with 3" fittings if they still exist . I have not and WILL not use the shiny round cats because they are not legal and won't pass a road side inspection , something that attempts to look and smell like a real cat would and thats what I want . Thanks in advance , cheers Adrian in Sydney .

What abour recoring the thing and consider replacing the top tank ? I gather you were using the GTR version of whatever series car you have ? A .

This thred is splitting into two with exhausts and turbochargers but exhausts are an interesting topic so maybe I can ad a bit . I've been researching exhaust stuff for my Evo 6 because I want acceptable road car performance and it has to be QUIET . Now back to Nissan I was looking at an early Z32 300ZX recently and I was remembering how they had two cats or at least one with two bores through it . By any chance can you splice two cats in before the engine pipes merg into one because if you can each cat is only catering to three cylinders exhausting half as often as the one cat would after the merge . Even if so could have legality issues because I'm told the cat is suppose to be in the std position under the car . Being closer to the turbos they should heat up a little sooner but I guess it all comes back to your and the states interpretations of the laws . These 6.2L Chevs seem to deliver the numbers so they must have something reasonable cat wise - x 2 . Turbos , my gut feeling is that GTRS GT2871Rs by two would not be ideal things , better suited to a single turbo app where a slight exhaust gas restriction is less of an issue . I don't know if anyones tried the 48 compressor trim version of the GT2871R , GTRSs are the 52 trim version . One thing I don't think anyones thought of is a version of the GT2860R like a "2530" but with 60 trim compressors . This is what the four cylinder version of the GTSS has and its possible that it would spool somewhere between RB26 GTSSs and RB26 "2530s" while not being that far behind the 2530s . Personally I think big power in a RB2568cc engine is a useless on the street . You can't use high rev power around the suburbs and if you have to go back more than one gear at highway speeds what was the point ? IMO only two things can pull the bottom end power up on an RB26 without compromising top end power . First is VCT and second is more capacity . There is no easy way particularly as centrifugal turbochargers are a compromise and at best they can span 2/3 of the engines usable rev range . Your call as to which suits you better ie the first 2/3 or the second 2/3 . Other means of airflow control ie variable valve timing DO make a difference but obviously this is not what Nissan was concerned about . They chose to fit GT2556R turbos to late GTRs and even these don't shove you in the back at "normal" revs/speeds . Anyway your calls , 2530 or GTSS if it was me and twin cats before the merge if at all possible . A .

After countless hours searching this is THE best site to find info on Hitachi and most other alternator bits . http://www.woodauto.com/Unit.aspx?Man=HITACHI&Ref=LR180724 Very good source of part numbers ie brushes regs and bearings , the go is to scroll down to the breakdown section and click on the reference numbers in red . Cheers Adrian

Yep , we got the back one out yesterday and the front one on the press this afternoon . For the record this Alternator is a Hitachi LR180-724 off an I think ADM Z32 300ZX with the NA VG30DE . Just for the record the small bearing is a 6201 DW and the pulley end one a B17-102DW3 . CBC has both and I'll get some tomorrow . The style of this alternator is very similar to what the Americans get on VG30 single cam J30 Maximas (85-94) and their wreckers are full of them , and everything else you can think off . For some reason USDM Nissans got higher amp output alternators than similar ADM cars did - maybe they were larded up with all the lounge mod cons . My Hitachi is actually for the old Dino Subie specifically because its mounts work on the old flat EA82T engines . Have to flick the rib belt pulley for a double V groove Subaru pulley and shorten up the spacer but the rest is supposed to be easy . Still have some reg part numbers to check , cheers A .

Hi all , does anyone happen to know the part numbers of the bearings in Hitachi LR180 alternators . I think they use NSK ones but not sure if front and back are same and what to get new . Also if anyone knows what the difference between 80 and 90a versions is let me know , guesses alternate stator . Thanks , A .

Well that map in post 5 shows the maximim airflow (on that map anyway) as 55 pounds of air which roughly equates to 550 hp . My old rule of thumb was to subtract 10% which lands it around 495-500 . I think what cuts it a tad short for an 82mm GT40 compressor is the lowish AR of its housing and to some degree its trim size . I think I have a map somewhere of the GT4082 and its possibly similar with I think a 50T version of that wheel . Better looking map though . Rifles through maps - no its actually a bit more at 570 odd - 10% = 513 . I'd have to look but I think they used a port shrouded compressor housing in the same ratio . That aside as usual the hardest parts of getting any turbocharger "right" are the turbine and turbine housing . If you get these in the ballpark the compressor end is reasonably easy - provided a suitable range of wheels and housings are available . Hopefully one day these larger frame center sections , BB ones , will be more readily available and people should be able to play around with turbines and compressors to get what they want . We wouldn't have as many issues with the smaller GT25 BB frame units if Garrett would gives us a wider selection of turbine trims (ie 78T GT30/GT35) AND a range of twin scroll twin integral gate turbine housings . If they can do it for Evo 10 GT3076Rs they can do it with twin inlet T3 flanged turbine housings as well ditto T4 flanges . A .

To the OP , sorry but I went back and re read and I had though you had a GT3782R which is a ball bearing diesel pickup upgrade family . If what you have is the plain bearing one then I'm not surprised it was laggy . While some used a 52 trim 82mm GT40 compressor the compressor housings weren't always port shrouded and that makes a difference . If you had access to the big shaft GT35 turbine that would help but then the turbine housing is no good . I'm not sure what AR ratios Garret made GT40 housings that were profile machined for GT35 turbines but I think they were pretty big . I think I have a GT3576 plain bearing turbo kicking around here somewhere but from memory it has a chipped turbine and the housing is something like 1.16 AR ratio . Honestly the BB ones are better and in time the Hino/Isuzu tax will come off them . The plus points would be a usefull TS turbine housing AR ratio and a suitably sized port shrouded compressor housing . Possibly the cheapest ball bearing big frame turbo is a T04 60-1 or the same thing with the T04R compressor marketed as a T04Z , I think HKS marketing came up with the Z = BB in this case A .

I reckon a GCG Hi flow or a Garrett GT2871R cartridge in the std RB25 housings - the 48 or 52T ones only . Prefer the OP6 turbine housing . If GCG everything is re used so nothing to buy apart from gaskets and copper washers . Garrett cartridge uses all different fluid fittings but are same as SR20 GT25 ones - cheap second hand and look factory funnily enough . Consider a 4.4 ratio diff to light it up more easily . A .

I normally would not reply to a PM this way but this silly site would not let me reply in the normal way . This is about a GT3782R on a 25 BTW . To the OP , these are pretty big turbos for a 2.5L engine and its not surprising it came on boost ~ 3500 revs . If your mate was using a std cast TS manifold it was probably going to be a limiting factor even though these turbos have the TS T3 (Euro T4 actually) mounting flange . Now these GT3782Rs were intended to be American aircraft carrier / ute "pickup" truck turbo upgrades and I think from memory they have the lower temp diesel spec turbine material too . Their Stage 1/2/3 were mainly compressor wheel options the largest (st 3) being the 88mm 52T from the GT4088R . The st 2 is same wheel as the GT3582R and stage one I think an 82mm 50 T version of st 3s wheel . Being a 7/7 bladed wheel in 82mm I'm guessing its stage 1 . Most GT3776s and GT3576s are big frame plain bearing turbos but there are a few BB units on some Hino and Isuzu trucks . In any case you can now get them in the smaller GT25 BB cartridge size because I think the later Ford Typhoon XR6s use this one . Ultimately most find that truck turbos are a PITA mainly because the housings aren't really suitable unless you intend to fabricate everything around the turbo or need a certain housing size not available as an aftermarket car part . Personally I think you are better of putting something on an RB25 that boosts closer to if not a little under 3000 revs so you get some benefit from the thing more often . GT30 based ball bearing turbos seem to work pretty well though I'd avoid the GT3082R/GT3040R version unless its the HKS spec one because the Garrett marketed ones seem to be a bit lazy to come on boost . I have no experience with Holset turbos but others here do , just remember the time/effort/money involved in fitting diesel truck turbos because it can be a painfull way to find the result is not what you expected . Hope this helps , cheers A .

I can imagine what people will day but I personally can't see how you can use 500 Kw in a street GTR , how fast do you intend to drive it ? Your calls , I'm not into GTRs but if I was it'd be GTSSs for a nice streeter or 2530s for a laggier top endier one . For the record JKavs original DP turbo use an external gate turbine housing and I can't remember what comp housing . All the then Garrett production engineers at the time said if you altered the spec of a GT2860RS it wasn't a GT2860RS any more . I can understand using the Nissan style T04B compressor housing but not ANYTHING but a 0.86 AR turbine housing - in a single turbo application . In my book if you can't make this turbo/turbine housing work on an SR20DET then you've done something wrong . And again as I've said in the past a GT2860RS is very very similar to a single type HKS spec Garrett "GT2530". All thats different is the compressor wheel and Garretts rather than HKSs T28 flanged GT28 turbine housing . Oh and Garretts originals used 0.86 turbine housings where HKSs use 0.64 turbine housings . The "S" in GT2860RS stands for altered spec to differentiate these from more normal spec GT2860Rs . They are a purely aftermarket unit unlike some GT2860/GT2860Rs which were std on SR20DETs . HKS did have Garrett make a mild GT BB turbo for SR20s and its basically a std BB GT2860R but with the better 76 trim NS111 turbine . Its cartridge number took me years to find and from memory is 446179-53 , its what you use when you drive an SR flat out and don't want exhaust heat/pressure to kill it . A .

That and the fact that most big diesels operate over a low narrow rev range . They also run on boost for long periods of time which you can hear out on the highways with trucks around . With petrol engines boost is there to give you a power boost for short periods of time because cars have much higher power to weight ratios than tow motors like trucks or diesel locomotives . Porsche can afford to do these sorts of things with turbos and in fact most mechanical do dats on their cars . They are asking for a lot of performance in todays overregulated lean burn high exhaust temp engines but the rich prix keep buying them too . I'd say these are very much an engine specific turbo and the struggling pleb car manufacturers just can't justify their cost . A .

No class they are not the same in SR20 guise . What Garrett call a GT2860R , like std SR ones , doesn't use the same turbine as a GT2860RS or the larger 0.86 AR turbine housing JKav its creator intended . Their compressor trim is smaller (60 vs 62T)as is the exducer tip height . GT2860RSs originally came fitted with a T04B 0.60 AR compressor housing and the Nissan style comp housing is really just a re packaged one with flanges rather than hose barbs . The DP turbo was intended to be a torque producing unit with low exhaust restriction which is why it had the big turbine and compressor housings for the size of its wheels . Its only really "big" for a GT2860R but thats enough for good road car performance or maybe racier use on 16 and 1800cc engines . You might find that these GTX series turbos have the same issues dualled on an RB26 as GT2871Rs do and for the same reasons . It takes more turbine shaft power to drive a higher capacity compressor mainly because of the mass of the extra air they are attempting to pump . I've been more interested in Mitsubishi turbos of late so not kept up with dryers in thr Garrett world . I think I remember reading that Garrett were intending to do a 60mm compressor version of the GT2860R and this would possibly be an easier thing to plonk on an RB26 . The possibly bit will probably hinge around GTX compressor wheels and port shrouded compressor housings - as in trying to get these larger PS housings snouts to fit where Nissan didn't have them . Really the only compact port shrouded comp housings I know of are the ones HKS had made for the RB20/25 spec GTRS , but they won't work even if you could get them because they are profiled for a 52T 71mm GT compressor - and the surge slot set for that wheel . I think you are basically stuck with something between 26 spec GTSSs and GT2860Rs (HKS "GT2530s are GT2860Rs)and if thats not enough contemplate small or at the most medium trim GT2871Rs . Same turbine housing and wheel size as these GTXs look like getting but with a comp wheel and housing that is known to fit . Some of you would remember how I used to suggest people hiflow their std RB20/25 turbos with a 48T GT2871R cartridge , theres not a lot stopping you doing this with GTR spec Garrett BB turbos provided they use RB26 style comptessor housings - the internally T04B sized ones . Not in reach of my lists atm but I think DP turbos were on paper good for ~ 35-36 pounds of air and the 48T GT2871R cold side ~ 38 39 pounds of air . Now strictly speaking its your calls and your money but I'd be wary of using a GT28 based turbo x2 that was getting healthy on the compressor side because you only have half the exhaust flow of your RB2568 driving each turbine so if the turbo is a tad lazy its very likely to show up as lag . A single turbo app like an SR20/RB20/RB25 has ALL the engines exhause gass flowing through it so its not as likely to feel laggy driving the big capacity compressor . Prime example , GTRSs work well on RB25s but by 2 can be a bit lazy on an RB26 . Really twin turbos are in a world of their own which is why often their spec is so different to a single if both twin and single units are sized properly in each case . OE RB26 turbos don't look small because Nissan likes exhaust driven CPU fans , they look small because they are and thats what works when theres two of them in an OE app . GTX compressor wheels will have their uses but theres bound to be situations where the existing GT spec wheels can do the similar things and maybe at times with less complications . Something is telling me that big G is doing some customer financed R&D in the aftermarket whilst tooling up to mass produce machined compressor wheels . There has not really been anyting radically new in the GT wheel world since the early 90s but others are doing billet wheels and I guess anything "billet" these days has a bit of bling attached to it . IMO they really want to be working on their turbines and turbine housings but its harder for their marketing departments to convince us that new shit hot non shiny things are the ones to buy rub you stinger on and fit to your car . HKS got around tis by fitting their purdy plate and charging a premium price . Nite all .