discopotato03

Twins are always going to be an expensive option and it adds so much extra associated componentry because two turbos need twice as much plumbing . Twin scroll singles are so much cheaper lighter and less cluttered than parallel or god helps us sequential twins . The complex part of a twin scroll twin integral waste gated turbo is the turbine housing and if they can get that right the rewards are huge . If you ever get the chance have a look at the turbine housing on a Mitsubishi twin scroll TD05 Evo turbo . Not particularly large but the work quite well on those 2L fours . We really could use a similar styled TD06 Evo turbine housing because everyone's high flowing them with TD06 family turbines and even the 10.5 cm TD05 housing is a tad small for maybe 260+ Kw 4G engines . The larger of the two Garrett Evo 10 housings is 0.94 A/R and designed around their GT30 UHP turbine . A .

Nismoid I'd say the increase at that point is a whole lot of things coming together in unison and all complementing themselves - a system . I don't really have time for a great long spiel but that never stopped me before ... Anyway most people are six cylinder minded and they need to remember fours are different like 180 crank degree power strokes where the inline sixes are less at 120 degrees . In a true twin scroll system the exhaust events are further apart so the cylinder blow down event has more time to completely exhaust the cylinder and allow scavenging in the valve overlap phase . Now because the TS does the high exhaust gas pressure thing when needed and low pressure when that's needed it relies on having very little resistance to flow downstream in the exhaust system . Geoff says its critical what goes on down stream of the divorced waste gates so if you have to plumb them back in there must be absolute most volume and therefore least pressure rise in that direction . Now I'm not up on SR20 head development and I can't remember if this fella use the early high inlet port non VCT one or the later one with lower less elegant inlet porting and VCT . I do know the ITB GTiR inlet manifold fits the early one and is way to go in a maximum effort engine though a heavier and more expensive . If you look at the camshafts involved here they I think are ~ 12mm of lift and ~ 260 deg duration , don't remember if this is on the seat timing or at 40 thou/1mm . Anyway high lift cams with modest duration are great for making an engine breathe whilst having good trapping efficiency and this tends to make engines torquey or grunty if you like from not a lot of revs . So add this to the twin scrolling and less pressure behind it and the gates and suddenly you have a system that can better charge and evacuate its cylinders more efficiently so the volumetric efficiency is higher - more to burn/less energy wasted trying to pump out the spent stuff . Now as to turbos I can theorise but its really hot air because its not like I've been there with these engines and dryers . That said my gut feeling is that the 52 trim GT37 compressor is the pick of the bunch (48/52/56) and possibly gives the best all round results . On paper they don't pump the absolute same maximum that the 56 trim one does but we are talking a whole 4 odd pounds of air by mass with the potential to make ~ 44 Hp - at the top at best . I never could find much about the 48 trim version because they were not that popular or sold in great volume which is a pity because I think they'd have it all over the 71.1mm 56 trim GT compressor wheel and give very close to the same max air capacity . Sadly people look at maximums so the smaller end of the comp wheel trim range at times is largely ignored with aftermarket turbochargers . Actually a while back one sold here 2nd hand but for more money than I could justify . Also as I've said in the past the 52 trim GT3037/GT3076R seemed to be the one people used in the past to get good all round results on 2L fours like SR20's , the one I used to quote had a lot of development on its long merge collector 4-1 manifold . It had a T25 flanged HKS 0.73 A/R GT30 turbine housing and started to make positive manifold pressure by 26-2700 revs which is not what people expected at the time with a GT3037 turbo . I also used to mention that the 52s were what HKS specified when the Japs wanted crazy big twins for outright drag Rb26's and as you'd imagine turbos like these twinned are not terribly responsive on a 2.6 litre engine much under I'm guessing 5500 revs . When you're using that much turbo for the capacity ANYTHING you can do to wake em up a bit earlier is a god send so I'm not surprised they didn't use the 56T ones in that application . Anyway twin scroll wasn't popular until people like Geoff Raicer decided to develop manifold and gate packages to complete the system . Mitsubishi does it OE on the Evos (4-10) but where most of it is not usable in other apps is because their turbos (4-9) are reverse rotation and the turbos mount the wrong way around ie comp housing towards the back of say an RB25 or inline SR20 . The one I'm a bit surprised no ones picked up on is that the Evo 10's 4B11 engine used a clockwise rotation TS turbo and Garret even make bolt on GT3071Rs and GT3076Rs for them . Now if you was to take the twin scroll twin integral waste gate turbine housing and make up an exhaust manifold with the Mitsy flange pattern you can have a twin scroll twin gate turbocharger without the cost and complexity of external gates . There's nothing stopping you asking GCG or whoever to supply the 3037/3067R in 52 comp trim form and provided they can get that Mitsy style Garrett turbine housing bobs yer uncle . Non std manifold yes with an all Garrett turbocharger having most of the smarts . Actually the aftermarket is on the edge of supplying turbos to the Evo world because they've been starved of turbos with balls (BBs) and only recently has HKS released their GT7460R BB turbos for the 6-9 and 10 Evos . Anyway other things are now becoming available like E85 juice at the pump so other ways can be used to get turbo engines up a bit sooner with high performance turbos . Hopefully people will take advantage of E85s increased detonation resistance and start using high CRs in turbo engines which should make the snappier and more torquey off boost . Another short one , cheers A .

My guess is that a GT3037 52T turbo if it has the port shrouded comp housing should be a far better thing than a real GT3071R . Nismoid the only map I've ever seen of the GT37 52T compressor looks good , better in fact that the GT37 56T maps . Admittedly the 52T one I have is not a genuine Garrett map but the islands are vaguely similar to the 56T ones but moved 4-5 lbs further left . The major change is the center island of highest efficiency - 78% and its wider that the 56Ts one . Trim wise the 3071R and GT3037 52T are different - 56T and 52T . If you mean inducer diameter then its ~ 55mm for the 52T GT37 and 53.1mm for the 56T GT35 wheel (GT3071R) . Don't be confused by my use of the the GT35 and GT37 compressor wheel families , they stem from the fact that those compressor wheels originally came from plain bearing GT diesel turbos and their turbines were GT35 and GT37 sized ones ie GT3571 and GT3776 . A .

No actually , the RB25's Hitachi turbo has a slightly larger passage in its turbine housing or at the least the ones I've measured have . The actual area radius ratio numbers are irrelevant because its not like you can alter them . You have a choice of small , a little larger , and large sizes - RB20/RB25/VG30 . All of the above mentioned turbos appear to have the same sized ceramic turbine . A .

Yes Stuart Wilkins is the one to speak to about 240Z/260Z cars . I'd try and do that soon if you are really keen and he may even ask you to trailer the rolling shell out to him at Mulgrave for an inspection . For fab work with the shell free of components is a real bonus . People used to say that L Series engines were unburstable but that's obviously not the case . Probably the torquiest NA ones were those with the 83mm LD 28 cranks fitted which got them up close to 3L . If anything the SOHC 12 port (6) heads were the breathing limitations and its not to hard to see the RB engine family as an evolution of the old L engine . I go so far as to say that the R32 GTST was a modern equivalent of the 70ish 240Z in 1989 . This is where you have to decide if its practical to modernise an old Zed or restore one to its former glory . Same deal with an R32 GTST though I know which is the safer bet driven really hard . The condition is known as Petrolysis Cranius and the only known cure is bankruptcy . A .

I think what Trent is trying to tell you is that an RB25 will offer far better bang for buck than a 20 or a 26 , cannot overstate too much what you get out of the extra 500cc's/larger ports/larger valves than a 20 has . In loose terms an RB25 is a more budget minded RB26 , same sized bores , same sized valves and the major differences are what bolts onto the head . An RB25 will make the sort of power easily that a mega expensive RB20 can only dream about and not cost an arm and a leg . Personally if you plan to build something up , RB30 short and a 25 or 26 head . Your call .

Yes all three use the same 60mm 84 trim GT30 turbine wheel so the housings should interchange . One thing no ones mentioned is the fact that of the three only the GT3076R/GT3037S has a port shrouded compressor housing and that definitely has some functional value other than the truck whistle . Sorry to bring HKS up again but you have to remember that they went to the effort of making their marketed versions of Garrett turbos work in engine/car specific forms . Now , most of the HKS spec single turbos for Nissan RB sixes use a port shrouded compressor housing ie 2530Kai/GTRS/2835 Pro/3037 Pro/3037S . Amongst the turbos Garrett make and market themselves only the GT3076R has it and I reckon its because it was a HKS spec Garrett turbo to begin with . That port shrouded comp housing makes the GT3076R/3037S turbo a very wide ranging unit because of it and allows you to use smaller A/R turbine housings and not get compressor surge . Actually thinking about it HKS had the smallest proper GT30 turbine housing size ever made and it was 0.61 A/R . I really don't think it would be a huge issue to run a 0.63 A/R Garrett turbine housing on either a GT3071R or a GT3076R , the problem with doing it on the GT3071R is the lack of a port shrouded compressor housing and this would show up any wheel speed miss match between the compressor and turbine wheels . If you look at what a "GT2835R" is you'd think that its cropped GT30 turbine if anything would attempt to spin the compressor wheel faster than the full sized GT30 turbine could for a given turbine housing size (yeah I know 0.63 vs 0.68) . HKS uses a port shrouded comp housing on that turbo and they wouldn't if they didn't have to . GT3040R/GT3082R has always been a bit out there and Garrett really should have reverted it to the HKS spec version (50T rather than 56T) compressor after HKSs six odd year exclusive sale time ran out . Some of you may have noticed that the GT3582R is now available with a factory Garrett port shrouded compressor housing and it would be a must have IMO if you wanted to run the 0.63A/R turbine housing , and if it were me the 0.82 one as well . If it fits a GT3582R it will fit a GT3082R and while possibly not cheap it should be a step in the right direction . Now to turbine housing A/R . If you use small ones its the hot side that will eventually run out of flow and do it earlier than larger sized turbine housings . Thats the price you pay for wanting to get the turbine up to speed earlier in the engines speed range . You have to match the turbine/housings gas flow to the compressor and its housings flow potential and its the ported compressor housing that gives more flexibility in this area . Small turbine housings and big compressors can be made to work provided the compressor housing can cycle the extra air that big compressor wants to pump when the turbos rotating group speed comes up early in the engines rev range . Obviously its better if the comp wheels capacity matches the hot sides capacity but its not always the case . Personal opinion only but I reckon the smaller trim GT37 compressors are a better idea if you want to use the 0.63 A/R GT30 turbine housing and as we know the 52 comp trim version is available because I tracked them down and GCG now stock them - yes in port shrouded comp housing form . The 48 comp trim version is a rare bird now and I think out of production . I actually wonder sometimes if I should have optioned for a 0.63 A/R turbine housing for my 52T GT3076R , its still new in its box and I may put that idea to GCG if they have one nor nil or SFA changeover . E85 is plainly now going to be a reality and I'm not so concerned about top end Kws in a RWD road car , having a sweet responsive low to mid range is much more important in the day of the radars etc than a power number . I really do think a 63A/R 52T 76R would be to an RB25 what twin GTSSs would be to a street GTR , good responsive street power thats more than enough 90% of the time . Wheelspin city without trying to hard and fast enough to put you behind bars quicksmart . A .

Nismoid the Garret turbine maps actually show the flow rates of the 0.82 GT30 and the 0.63 GT35 as having similar maximums though IMO the GT30 0.82 is the better map , these are with the T3 flanged GT30 turbine housings BTW because the 30 and 35 both use them . Not my project and don't think I'd build such a top endy RB20 but to each their own . Now there is another option in the GT3082R family and its what used to be called GT3040 in HKS speak . What it is is same deal as the Garrett GT3082R/GT3040 but with a 50 trim rather than 56 trim GT40 compressor wheel in it . My old HKS list shows its good for 20 more PS/Hp than a GT3037S/GT3076R 56 trim . I have a compressor map of a Garret large frame plain bearing GT4082 which uses this same compressor wheel and it shows the the maximum airflow rate at the bleeding edge of about 57 lbs so potentially 570 Hp if you go by maximums . This is in a 0.58 A/R GT40 compressor housing which is crudely speaking of a similar size externally to a T04S o.70 A/R one , maybe a smidge smaller but port shrouded . It may even pay the OP to look into Mitsubishi turbos because they tend to use reasonably big wheels in smaller trims than Garrett does sometimes and that could pay off when you want power over as broad a range as possible . BTW what does the OP want to do with this RB20 ? A .

Hi all , in Sydney there are a few servos going under the AP banner and I noticed the 98ULP is claimed to have 10% ethanol content . I'm curious to know peoples opinions on fuel octane and the different ways that a given fuels octane can be increased and the power potential because of it . A good friend of mine in the automotive trades for nearly 40 yrs claims that if anything the lower octane fuels are better power developers with the only downside their tendency to detonate in high cylinder temperature/pressure situations . He says that the higher octane petroleum fuels abilities to resist detonation actually make it harder to light the fire and burn efficiently . Where I'm coming from with all this is that I suspect AP may be boosting the octane rating of say 95 ULP with ethanol and if that's the case is it possible that their 98E10 may burn better and possibly have a small edge over straight 98ULP - no ethanol . I'm finding it actually resists detonation better than BP Ultimate in my old dinosaur tech (1986) turbo Subaru and I think it makes my Skyline run smoother as well . Is anyone game to give this fuel a whirl in a high horsepower roadie ? BTW it sells for around 1.32/L recently anyway which doesn't appear to be that much different to Ultimate - depending where you get that from . Opinions ? Cheers A .

I reckon just a good tight std RB25DET , maybe a Neo if available , and a 2835 Pro S with the 0.68 turbine housing should work well . A bit more exy but its a bit hit and miss with those 3071Rs and the full sized GT30 turbine . For whatever reasons that cropped turbine and the HKS turbine housing seem to work a bit better over a wider range and the ported comp housing takes care of any surge . Cheaper and easier would be an RB spec GTRS turbo . I'd be ditching the 4.6 diff in a car that light and opt for a 3.9 or even a 3.7 ratio final drive . These are still around in the type of long nose R200 that fits under the bum of those early Zeds . A good RB25 should make more torque down low than a carburetted L24 or L26 so all good . Yeah , tight Neo 25 with a GTRS would easily be quick enough on the street and very easy to live with as a daily . With Stuarts steering and suspension bits you could make a very impressive classic that could embarrass many a current lump and hold its own steering/handling/braking wise . A bonzai engine is expensive where a more conservative and budget conscious one leaves money to make an old car THE complete package . Nicer to drive and easier to sell for good money if you get tired of it . A .

Yes that's how I would expect these -9/GTSS turbos to work . The reason why they feel good is because they make good torque at lower revs so you don't have to chase high revs to get some pull . Yes the 2530 and similar dryers make the numbers buts that's because the higher RPM numbers artificially raise the Hp/Kw number . Torque is the measure of turning force and more torque means more acceleration and yes the ability to pull higher gears from the lower mid range engine revs wise . Eventually people tire of being impressed by high revs and want things that haul from lower revs , often just as fast but a LOT easier to drive and live with . The feller in the post above I'm sure can understand what I mean when I say these turbos to a degree mimic a larger capacity engine which is what GTRs always needed . With stripped out tarmac racers no one cares what happens south of 4000 revs but when in road going guise that tonne and a half takes some moving when stopping and starting and slothing around in today's traffic levels . I personally think anyone who wants a fast std capacity road weight GTR has rocks in their heads for not using these turbos . These are good road cars units , maybe not so good for drag or a real racer buy they are so far divorced from what makes a road car good as to be irrelevant . Your opinions your calls , I don't like/have GTRs but if I had to have one they are what I'd use on the street . A .

I know someone from here once spoke of building an NA RB26/30 up and plonking into a Zed with high comp pistons and healthy cams . My memory is vague but I think an early factory 240Z weighed in at or a little under 1000 Kg ? Yeah the nose of a Zed is quite long I think in relation to the strut towers and the engine sits a fair way ahead of the effective front axle center line . I think the rally peeps weld braces from the towers down towards the front of the rails but theres no real opportunity to triangulate things . Same deal as 6 cyl LC/LJ Toranas . A .

Now lets see , a hotted up RB25 in an early 70's 240Z . Before you go gangbusters have a think about what a 240Z Datsun is and its steering/suspension/braking limitations . Actually I strongly suggest you speak to Stewart Wilkins because he has had a long term interest in those cars mainly from a rallying perspective . I have seen many big dollar tear down to bare metal 240/260Z builds there and I wouldn't think there would be much he couldn't tell you about these old cars . They start out with a very long structurally unsupported nose but a least they had rack and pinion steering unlike many cars of the era . They do have problems with bump steer and Stewart has had many custom parts made to fix most of the front end woes in Zeds . ek think hes even had custom hubs made to take 5 x 114.3 stud pattern wheels , and CV/pod joint style rear axle shafts to replace the archaic uni and ball/splined std ones . They can do the conversion work with custom bits to fit GTR Skyline brakes too . I'm pretty sure they told me that Zeds really need a good welded in roll cage to get a reasonably stiff shell becase std and at nearly 40 yrs old they move around like a cock in a sock . I have seen pics of aluminium radiators and suitable intercoolers in the nose of a Zed but you don't have as much room as you would have in an R32 or 33 . You obviously have a project in mind but in a way its a shame not to se a well built L28 under the lid of a real Zed and the triple 45s always created the essential growl in a hot 240/260 . Cheers A .

There is actually a very simple electrically heated air bypass valve that Nissan's have had since the 80's , well I think all the pre electronic throttled ones . It looks like half a small dumb bell and has an early Bosch injector fitting on one end of it . How it works is that it contains a metallic strip than when heated flexes and rotates a plate with a hole through it so it slowly closes up the air passage . By slowly I mean approximately 2-3 minutes . Another clever part of this gadget is that its usually bolted to a surface that conducts engine coolant so if the engine is started hot the internals stay hot and the rotary valve remains closed . Another nicety is that your computer doesn't need any outputs other than to the fuel pump relay because its that circuit that powers this valve in OE applications . I can hear people say why wouldn't it be powered by an ignition power supply . The reason is that if for some reason you have the ignition switched on without the engine running the valve won't close up because the fuel pumps power supply is cut other than to initially prime the system . These devices are merely there to add extra air to a stone cold engine , the "cold gun" effect of cold chambers/valves/pistons means an engine needs more air until it warms up enough internally not to lose much of its combustion heat and efficiency to cold surfaces . Some non synthetic oils also have a lot more drag when cold so this can add to the cold start woes . If you search for these valves under AAV or auxiliary air valve you should find some good info . Note that these are not a controlled IAC or idle air control valve so they can't regulate hot idle speed . Food for thought , cheers A .

Probably the question to ask yourself is do I want a car that's good to drive 75% of the time or 25% of the time . Obviously you can't get around in hero mode all the time and expect to keep your licence , I think a car that has some stick at sub light speed will be more fun more often and that why you drive an enthusiasts type road car . A .

A lot of things come in to "play" here . Before I start you can buy these turbos brand new from Garrett at a Garret price . Also I asked GCG a while back and at that time they couldn't get new cartridges for these turbos separately . Now , sometimes turbos come along at a really good price but HKS spec ones usually attract a "HKS tax" . To be really sure you need to see these turbos with their housings off to check for chipped/bent blades and oil leaks AND chewed out the hot side piston ring register in the bearing housing . Personally I would ask your local Garret supplier what the rebuild cost is and add that to the price being asked for second hand turbos . Naturally brand new ones are the best option BUT be VERY careful with second hand ones because they can owe you more than brand spanker's ones if they are damaged/badly worn internally . AKAIK the only unique parts in these GTR spec GTSS/707160-9 turbos is the compressor wheels and the comp housing that's been profiled to match them . I know its not my money in question here but if it were me I'd be thinking hard about how much effort goes into removing and replacing turbos on an RB26 in situ . Worst case scenario you R/R these ones on your car and they lemon out . So pull them off again and how much are you out of pocket at this stage ? You have a right to expect new turbos to function properly and have some comeback if they don't . You are in a grey area with used ones particularly if you don't know the history of the owner and their cars . In this situation its impossible to know how used up they are and what sort of reliable life they have left . People buy factory hottie cars to drive them enthusiastically but how much mechanical sympathy and maintenance sense they have is often a big unknown . Your call , cheers A .

I seem to remember seeing second hand HKs ones on occasions , not sure about the tube sizes though . A .

The question you have to ask yourself is does it go well/better in your opinion - butt dyno . A lot of people fall in love with a target power number and can't sleep at night if it doesn't materialise . If the thing goes well enough in your opinion who cares what the number is . It seems you are into easy upgrades which is the practical economic approach but there is the chance you may have undershot and overshot with a couple of things possibly . The turbo you have is from an R34 GTt and from memory they crank out ~ 206 Kw , the SMIC came from a 184 Kw R33 RB25DET . The things both versions of the RB25 have are obviously the extra 500ccs and larger bores/ports/valves . The R34 versions sometimes use a larger sized turbine housing than the 33s and they get away with it through things like more sophisticated engine management and VCT and slightly different std cam profiles . There is a chance you have the larger turbine housing , which incidentally was originally designed for the low boost pressure Z32 VG30DET engine , on your R34 turbo and its only a LOT bigger than your original RB20 turbos turbine housing . I reckon if the slightly larger than RB20 RB25's turbine housing helps the R33 crank out 184 Kw its possibly a better option for an RB20 than the largest VG30/RB25 Neo's turbine housing . Should give you a bit more low to mid range and not lose anything up to possibly 200 Kw . As for the SMIC the R34 GTts one is a bit taller and deeper through than the R33s one and if it was possible to fit one reasonably easily into an R32 GTST its what I'd do . Food for thought , cheers A .

It sounds like minds are made up but just think about this for a second . Outlet or dump pipes are bastard to get off the back of a turbocharger in situ and it is nice to be able to disconnect the exhaust from the bottom of the std dump and remove the turbo and cast dump pipe together . Its much much easier to remove/refit a dump pipe on the bench and fit the complete assembly back on the exhaust manifold . Then simply re attach the front pipe to the dump pipe in the standard location . If the dump and front pipes are both 3" or whatever then its got to be better than std - and much easier to work on . Imagine at a later stage you go to change a full exhaust and don't want to have to stuff around removing the one piece dump/front pipe from the turbo . Its a lot of fiddly work to do and the chance is always there of breaking studs or bolts off in the turbine housing which usually means turbo out to fix them . My vote goes to a bell mouth with the joint in the factory location mainly because is a shitload easier to work on and if you break any fasteners their already apart and nuts and bolts (good ones) cheap and easy to replace . Also importantly you MUST re use or replace any factory dump pipe braces because larger diameter exhausts are a LOT more rigid and put a lot more leverage into the turbo and exhaust manifold . RB engines are known for cracking exhaust manifolds particularly if the dump and turbo have to carry the weight of the exhaust system because some cork head removed all the factory hangers and didn't replace them . I also thoroughly recommend you use some sort of "soft point" up the front of the exhaust so that the engine when it moves around doesn't put stresses into a more rigid exhaust system . Soft points can be those stainless concertina things with the outer braid or IMO preferably one of those spring loaded carbon ring swivel joints . These can be got through any exhaust place that gets the odd truck through because trucks use big ones and I've seen plenty with 3" exhausts or larger . The swivel joints are a bonus because like flanged joints they are usually easy to get apart and separate exhaust sections . The golden rule with exhausts is to do them properly and not have them act up later , set and forget . Your calls , cheers A .

Just for the record RB26 specific HKS GT2530's are not the same as -5s , the cartridge is very similar BUT the compressor wheel is different - 60.1mm 63 trim . Sorry for the boring history lesson but . Garrett developed the compact ball bearing center section and based its bearing housing around their T25 bearing housing . This is why those ball bearing center sections were/are known as the GT25 BB center section . Its in all of them from the current smallest GT2554R to the largest (in that frame size) GT3582R . Now back in the late 80's when Garrett were developing these things they initially used the TB25 turbine and a bit later in the GT (Garrett Technology) era their GT28 turbine wheel . Now at that stage they called all these turbos using the GT25 BB center section with TB25 or GT28 turbines GT25xxR turbos ie GT2530 . Often HKS cut the "R" off the end , all the R means is rolling element or ball bearings . Later on Garrett chose to change their numbering system to reflect the difference between the TB25 and GT28 turbine based turbochargers . Note here that the TB25 turbine was only offered in 62 trim where the GT28 turbine can be 62 or 76 trim . If you look at the "turbobygarrett" web site and specifically these "GT"25 and GT28 based ball bearing turbos look closer at the turbine wheel diameter and trim numbers . From memory the TB25 turbine is 53mm where the GT28 ones are ~ 53.8mm diameter . Its easy to confuse the TB25 turbine in 62 trim and the GT28 turbine in 62 trim because looking at the numbers its only that sneaky extra 0.8mm that's different and if you don't have the turbos or pictures up the butt of them its easy to miss it . BUT , they are very different turbines and do different things . All else being the same the TB25 one will be more responsive if a tad more restrictive but in OE apps it works quite well . Garrett uses the 62 trim GT28 turbines in turbos like the GT2854R/GT2859R/GT2860R (707160-7) . Their intention was to have a slightly lighter (9 blades vs 11) more open bladed turbine so they could trade a small amount of turbine response for a bit less exhaust gas restriction through the system . Its the way to give up a bit right down low to make a bit more power through the mid range and top end - remember everything's a compromise . Everyone seems to be talking about the 707160-9 turbo or in HKS speak the RB26 specific "GTSS" . A lot of smarts in these turbos , they are designed to start a bit earlier than the R32 spec GT28 bush bearing turbos and have a bit more flow potential once the engines loaded up . If you look at their specs they are ALMOST the same as the 707160-7 turbos . Look closer at the compressor wheel diameters and trim sizes , the -7 is from memory 60.1mm 55 trim where the -9 is 59.6mm 56 trim . Then look at the compressor maps , big difference and given a choice I'd always take the -9 version . This is what happens when a turbocharger manufacturer puts more effort into developing a given turbo to match a specific engine and performance ask . Everything in these -9 turbos is Garret and unlike some other turbos developed by Garrett for HKS there are no HKS custom housings that Garrett won't supply . The result is you can buy a Garrett turbo for a Garret price and miss the "HKS" tax at the register . Now to the larger 76 trim version of Garrett's GT28 turbine . Its the one used in the HKS spec Garrett GT"2530"/GT"2540" and Garrett's own marketed GT2860R 707160-5 and GT2860R 739548-1/-5/-9 and all the GT2871R turbos inc the HKS spec GTRS . Also in the HKS spec SR20 version of the GTSS which has the GT28 76T turbine with the 60.1 mm 60T compressor found in OE SR20 turbos . Its hard to find cartridge no is 446179-53 . When you use the larger 76 trim GT28 turbine based turbos twinned on a std capacity RB26 you will lose a lot of the bottom end that nice turbo street cars have . Its the payoff for having turbines (x2) large enough to generate 600+ crank Hp with . The trouble is that if for what ever reasons you don't run them up near that power level then the turbine lag you put up with is basically all for shit . You have to decide if you can put up with an engine that wants to haul from 3500-4000 revs and not be anything special up to maybe the mid 3000's . To me that's an unacceptable compromise in a 1480 Kg Skyline if its used 99% of the time on public roads . I think if it were me I'd want to feel some useful torque maybe from 3000 up and if it nosed over around 7 I wouldn't feel short changed . I couldn't hack a heavy car that wouldn't go much under 3500 , turbos stuck in angel gear mate ? But anyhow that's me and I'm not a GTR person , if I had been it would have been conservative R34 BB turbos or those 707160-9/GTSS ones . To complete the story the HKS spec GT2510 has the TB25 turbine (54mm 62T) teamed up with the 60.1mm 63 trim compressor from their GT2530 . Basically a 2530 without its GT28 76T turbine . Clear as mud ? Cheers A .

The other option is to try and find a cheapish R32 GTST that isn't dead and have a play with that . All I can see is good money being spent on that R31 and in Aussie form they are heavy and lack a decent rear end and brakes . I think an R32 would be lighter more nimble and have a more suitable driveline/suspension/brakes std . I think the best thing you can do with the R31 is fit a tow bar so you can hire a float and haul the 32 (no need for rego etc) to the events . A .

If you mean by Injector Dynamic ones EV14s then they are Bosch too . The thing is that everyone's raved about IDs EV14s and how much easier tuning is with them - even with big ones like 1000cc and more . If I had my time again I would have used them in My GTS25T instead of the Nismo 740s I have . Those EV14 ID injectors are known to be very uniform very fast acting even at quite small pulse widths . If you do searches on them you find them OE on late model cars running higher than 90s era fuel pressure and often returnless systems . They do actually return fuel to the tank but most of them are in tank and so is the pressure reg . If drivability and fuel consumption mean anything to you go with the most accurate fast acting and uniform injectors you can fit . Your tuner if he's worth his salt will thank you for this . A .

I have not used those HKS cams but the relevant Tomei Poncams are hard to beat from a drop in and work well perspective . I have read accounts of the HKS longer period exhaust cam set and no one I remember really liked them very much . The theory I think is that the longer period exhaust cam is supposed to make up for the RB heads slightly smallish exhaust valves but in order for this type of exhaust cam to work you can't have any significant pressure downstream of the exhaust valves . If you do you get enhanced reversion effects because the longer cam reduces the cylinders trapping efficiency giving you a lower dynamic or effective compression ratio . I think cams of about equal duration are a better bet in RB road engines and if you are willing to remove the head and have the exhaust valve seats machined for slightly larger valves they go in easily too . R33 Poncams just work , easy to fit and no real loss anywhere . A .

I would think that the sensible approach would be to use all the engine electrics (sensors) from the S1 engine . Things like water temp/knock sensors/oil pressure switch/complete throttlebody and TPS/02 probe/CAS . Possibly the original resistor and coils as well . Most people find that if you use the complete set of engine electrics from their native car things tend to work better . I can't remember if they're different with R33s but it probably wouldn't be a bad idea to use the original alternator and power steering pump , if they are in good working condition its something less to screw up when you start the replacement engine . The S2 ones may or may not be the same so why not go with a known quantity . Same with AC comp . Your call but I wouldn't miss the opportunity to inspect the clutch and replace anyway its throw out bearing before its installed and any problems discovered when its all together . Also I'd ALWAYS remove the flywheel and replace the rear main bearing oil seal , its a shame to find it leaks and have to then remove the gearbox/clutch/flywheel to get at it later . Optionally you could fit a new water thermostat and front crank pulley oil seal . I'm just suggesting these things because they are so much easier to get at with the engine out of the car , must check all water and vacuum lines whilst you can reach them easily . Its what I'd do , cheers A .

Just ignoring the numbers for a sec are you happy with the way it drives ATM . I would have thought that 290 at the wheels of a GTR should feel pretty good . I know many won't agree but if it impresses you as it is do you think the money needed to chase another 30 odd is worth it ? A .