discopotato03

I went back into Mafias 300 RWKW Adventures thread to see why he chose the 0.63 AR housing on his GT3076R . He said he'd had butchered VG30 and RB25 turbine housings then a 0.82 and finally the 0.63 one . What he was looking to avoid was turbine lag and detonation . Pre WMI his wasn't knocking up to around 270 RWKW , someone asked him what the difference was and he said 10 degrees of timing and 30-40 RWKW . He mentions 20 degrees of full load timing with WMI and 700 Nm from 3100 to the redline . This was ~ 7 years ago and you'd have to think that within its limits a GTX3067R is hardly going to be less efficient than a GT3076R . My parting comment is that water methanol injection cannot stop an engine choking on its own exhaust even if you drown detonation . If it really had been super restricted it wouldn't have been happy to rev and been very reluctant to hold 18 pounds of boost much past the upper mid range . The X67 wheel has to be spinning faster to pump the same weight of air at any point than a GT76 one so the turbine turning faster also creates less resistance to exhaust flow . If Mafia claims he was only just reaching the limits of his turbine housing its hard to see how the lil X67 is going to create mayhem . A .

I'd have to re read Mafias 300 Kw adventures thread to get his exact opinions but I do remember him saying it pulled like a V8 from I think around 3-7000 . If it wasn't a volumetrically efficient system it wouldn't have worked as well as it did . I have no doubt that up top things would have been toasty without the water mist cooling but he never cooked or melted anything and his leak down tests were always good . Now , I think the perception of the 0.63 housing being a choker chain is in relation to larger compressor ends because that's all we had until recently . The idea of an RB25 being a rev engine isn't something Nissan worried about considering the miniscule turbine side they get standard . I find when I have my tune right that I get surprisingly good part throttle torque and flexibility and that's off boost . You can argue it any way you like but the smallest GT30 hot side is a big increase over the standard turbo and still higher flowing than the few GT28 alternatives . Now I don't disagree that easy exhaust outflow is a good thing but not getting a power boost from positive air pressure where you want it is hardly a good thing . IMO it isn't good enough to tell people that's how it is so lump it . They are the ones who know what they want and they are the ones they have to please . If they can't run full bore up the road at 6-7000 revs the bit they sacrificed down low is all for nothing . One day we will hopefully get a comparison of a 2835 Pro S and a GTX3067R 0.63 AR . If the result is similar what does that say about its hot side - or peoples acceptance of the HKS turbo ?

I think it is possible to compare turbo systems with/without WMI before heat and pressure gang up and detonation sets in . It'd be a pretty piss poor turbo engine that wanted to detonate just as the turbo started creating boost and or at low boost pressures . That's why I suggested lower power and torque numbers (less heat/pressure) than Mr Mafia had and I think its reasonably obvious that a 3067 is going to be spinning faster for just about any air flow rate than a GT3076R 56T . A faster spinning turbine presents less flow resistance than a slower one for a given housing size . Comparing a GT28 based turbo like a GTRS isn't going to teach anyone much about GT30 turbos even in smaller housings . The 28 turbine is ~ 6mm smaller with narrower tips and the nozzle and volute is nothing like a GT30 housing . NS111 and GT30 UHP turbines are nothing alike , chalk and cheese and everyone at Garrett that ever spoke of them said the 60mm NS111 is a more efficient animal than the GT30 UHP . If GT30 was the titz competition turbos would use them but they don't because they don't work very well in serious competition applications . They won't give us the real 30 series turbine so we soldier on with the high temp material GT30 diesel turbine in 10 blade form . I did once see a pic of a Garrett competition turbine that was even bigger than 60mm and I suspect there's a GT35 sized version of the NS111 or similar too . Anyway IMO a GT30 turbine in a 0.63 AR turbine housing is going to work better than a GT28 in even the "big" GT28 0.86 turbine housing , not that there even is a T3 flanged version of that - from Garrett anyway . I agree that Garrett should have made a 0.73 AR GT30IW turbine housing and I'd have one if they did . I'm still not convinced the 0.63 is a waste of time if top end power isn't important to the user . In fact just today I changed from E42 to E85 so my next tune has the best chance of blitzing 300 plus on my car . If I'm still not convinced I'll consider trying a 0.63IW housing and if anyone wants to sell me a good used one PM me please . I'd love to see one extrude honed to give it every chance of being a good road car system . I don't imagine there is a lot of difference performance wise between a GT30 0.63 and a 2835 0.68 hot side . Not too many people bitched about surge or boost control issues with the 2835 Pro S and that's not exactly a GT30 0.82 is it . HKS sorted their turbo so it didn't f*ck up and by that I mean surge or have boost control ills . You'd think if the GTX67 hot side was going to turn to shit it would do so worse in GTX2867 form than GTX3067 form . Literally the same animal with a smaller turbine and turbine housing . I'm pretty sure that if you threw a GTX2867R in the HKS 0.64 AR IW T3 flanged housing at an RB25 it would have similar limitations top a GTRS (GT2871R 52T) or the KAI version of the 2835 mentioned in the other thread . If they were going to surge they'd be doing it on 4 and 6 cylinder engines and I don't hear anyone with SRs etc having issues . Now your calls but I think the X67 cold side was designed to go to the limit of the GT28 hot side , then Garrett decided to turn it around and fit a turbine that would take that X67 cold side to its limit with less exhaust restriction . The GT30 0.63 hot side flows as well as the biggest GT28 hot side options get and its hard to guess how big a GT28 turbine housing would be to get anywhere near a GT30 0.82AR flow - if that were even remotely possible . From past examples we know GT2871R 56T turbos were problematic , laggy and surged because Garrett didn't have port shrouded compressor housings for them . HKS fixed it with a 52T compressor and a port shrouded housing . The last issue was a T3 flanged turbine housing and they had these too . Anyhow to each there own , I know what I'd do . A .

Yes it was unfortunate and hardly honest of HKS , or their reps , to claim the KAI was going to be as good as the Pro S version . I remember looking at pics of that turbo here and thinking hang on , no way the 0.64 AR GT28 T3 housing was going to flow like the Pro S one . The machined out turbine housing may flow a little better than it would with a GT28 turbine in it but from Garretts questionable turbine maps the efficiency numbers aren't very good . I don't think any turbo with the cropped GT30 turbine ever worked terribly well unless it had one of HKSs GT30 turbine housings machine to suit . For some unknown reason Garrett haven't offered their GT30IW housings to suit this turbine , maybe there isn't enough material in their castings . Just on power figures and 2835 Pro S , there was an optional 0.87AR Pro S housing if you didn't like the usual 0.68 one . Don't know the boost onset difference but power limits would have been higher with it . A .

Yes you can go past GTRs because GTSTs and Evos are easier and cheaper to work on . If you are rich and pay people to work on them GTRs are fine , they lack cubes for their mass buts that's life . Better feel and balance in a GTST/GTt than an Evo in good nic , no way in hell . Far more feel in an Evo 6 GSR steering handling braking wise that a GTS25T , I have both and they both have Pilot Sport Rubber (PS3 Evo) (PS2/PSS R33) . Both have light 17x8.5 wheels , the 33 has the full SK Bilstein kit and the 6 has Whiteline bars and Evo 9 rear Bilstein struts . Evos are closer to GTRs than GTST/GTT package wise with less comfort and excluding outright power/speed probably better than a GTR in the twisties . Driven wheels grip better than "idlers" and Skylines have a large portion of their engine out past the front wheels . Aside from the lack of FrWd that's why M3s tended to be better handling straight six performance cars than Skylines . Look how far back the engine is in relation to the front wheels , and how much closer to 50/50 weight distribution they have front to rear . GTR isn't as bad as the original Audi Quatros were but they were both the result of fitting 4WD into an originally RWD or FrWd platform . Evos are pretty much the same as Lancers back to the front doors except the floor pan from that point is totally different . Ralliart designed that not MHI , up to E6 anyway , so they had lots of freedoms with rear driveline suspension brakes wheels etc . The thing to remember is that Evo was designed to be a Tarmac Rally basis where Skylines were open road touring cars - GT . It takes something special to be agile and sharp on slippery constantly changing surfaces and they live to be thrown around with everything spinning ALL the time . I was in my mid 20s when GMS raced R32s in Grp A and I don't remember seeing them spinning all 4 most of the time . I do remember them looking smaller and more nimble than the V8 powered taxis and Sierras were really the only serious opposition . Also it wasn't always wet and slicks are the gun thing in the dry . If you had the same tyres and tarmac suspension , and the same power with equal top speed gearing a GTR probably isn't any better than an Evo , possibly on a fast circuit because of its extra capacity but on one with hairpins and S bends my monies on the Evo . IMO for dedicated drag race a tubbed RWD is the go . A RWD Skyline if you punch it everywhere would better suit the "skid/drift brigade" than an Evo because at the same speeds the Evo does more easily and neatly . I guess it's this trying to find limits that some people like . They are higher in Evo and GTR which means going faster to find them - way way faster than speed limits allow and I say again when you lose it at that kind of pace the crashes are often monumental . You often hear people say AWD cars like Evos are so easy to drive that they make a mug look good . The reality is they get out of shape at higher cornering speeds and when they do they are harder to recover so no the technology doesn't automatically save a goose from themselves . A .

Your call but I think GT28 stuff is a little small for an RB25 unless it's in a very mild state of tune , I definitely wouldn't swap your turbo for a GT28 based one in a GT28 housing like the HKS GTRS one for this reason . I got mine (GTRS kit) for a reasonable 2nd hand price off Wolverine because it was an easy install and has more potential than the std RB25 ceramic dryer . If 270 at the wheels = 300 at the crank then that's what I got with a few top end mods on E70 . Turbo on its knees . GT30 turbines are about 6mm larger in diameter than the GT28 and in 84 trim size vs the 28s 76 trim . So GT30 turbine blades are going to act as longer torque arms than the GT28s ones which is better where possible to drive compressors into boost . Again if you look at Garretts questionable turbine maps the gas flow through the GT30 0.63 AR is very similar to the GT28 in its larger 0.86 AR version - which is only available in T2 flange . Hot side sizing is always a juggle of turbine speed vs exhaust flow restriction and the "restriction" options are basically housing AR size . Since you can't easily get a 0.86 T28 housing in T3 flange the logical solution is to go GT30 in 0.63AR T3 flange . Uninformed miss guided - mmm . No offense but I can't see any less restriction or potential boost control issues with the "big" 28 hot side vs the "small" 30 hot side so going 28 for the sameish flow doesn't make sense to me . I think everyone agrees to get boost earlier the turbine has to spin faster sooner so the usual method is to go down in turbine size . I feel sorry for the lack of love for that 0.63 housing and its hard to imagine Garrett making them to start with if they are so useless . This much I can say , the 0.63AR will spin your turbine faster sooner and is the simplest option available . I can also say that people get 300 plus wheel KWs with the standard exhaust manifold so it probably isn't as useless as some would have you believe . I see your point about an increased flow restriction at part throttle and off boost but engines lightly loaded generally have low exhaust flow , this is still way way better than Nissan had it standard and significantly better than a GTRS GT28 0.64 AR hot side . Headers , not cheap or easy or as stealthy and I think a lot of though would go into a manifold that's going to excite a GT30 turbine in a 0.82 AR single scroll housing at low med revs . I think the best shot there would be with a twin scroll 0.82 housing but that's more money external gate/s and still an unknown quantity . My instincts are telling me you want more shove (torque) further down the rev range so solving that and not being worried by dyno numbers is probably the path . Mr Mafia did it , it was reliable , it didn't kill the engine and it was very likely driven and dyno'd hard . I don't remember him mentioning boost issues and while he did use WMI it all worked out - on a GT30 turbo with a larger compressor and compressor housing . AND with that poor unloved GT30 IW 0.63 AR turbine housing . Numbers like 320 RWKW and something like 700 Nm of torque . I think if you got to 270 RWKW with 450-500Nm of torque your engine would hardly choke to death . Mafias was an unopened R33 RB25 meaning standard pistons and they didn't turn into melted pizza cheese . Gotta run but look into dramas with 0.63 housings because I reckon you'll find other factors involved .

We have to remember what was available when HKS put those GT Pro S turbos on the market - SFA . There were no Garrett IW GT30 turbine housings then so you were pretty much stuck with a Pro S or an external gate . Or some bastardised machined out dinosaur T3 IW housing . If you can't rat up a Pro S turbine housing then you may need to look at the GTX3067Rs , we haven't seen one yet on an RB with the 0.63AR IW turbine housing but its worth consideration . The 2835 KAI looks like a band aid for the Pro S version . It's basically taking a GTRS and putting a cropped GT30 turbine in it so the value is a slightly larger and heavier turbine in a T3 flanged GT28 0.64 AR turbine housing . It bolts straight up and takes the standard dump flange . I personally reckon that if you can't get a Pro S housing and its unique dump pipe (or make the dump) you are better off with a GT30 based turbo even if it means using the smaller 0.63 turbine housing . Once your set up for the manifold spacer and GT30 IW dump pipe you open up a range of turbo options you don't get with much else . Had Garrett had the GT30IW housings back in the day there probably wouldn't have been Pro S housings and dump pipes . Also consider Hypergears turbos , cheers A .

There is never going to be middle ground between Skylines and later Evos . There is no perfect performance car either . People ask me which of mine is better and I just say they're different . Much of what people like is different depending on their mood and how they drive at the time . When the bloods up an Evo suits because everything is sharper steering braking handling wise . They are deliberately biased towards hard driving because originally they were homologation specials - up to E6 anyway . This is what it took for manufacturers to have a potent contender and a legal race car basis . It's the reason why GTRs only had 2568 odd ccs out of the box . I think Evos were popular in the day because it gave people the chance to buy a drive a tamed down race car basis . Most are GSRs so you get fast glass AC sound Momo Recaro n Brembo brakes AWD turbo close ratio box off the show room floor . It gets harder edged than these in the RS models , pov pac stripper options make them lighter faster and the gearing gets even shorter - think 4.8 diffs . If you want a fast urban street burner legally an RS Evo with a bit of work is very hard to beat . It's also an uncomfortable fussy thing to drive "normally" because it's not intended to be an everyday commuter . The sad fact people is that you don't go flat out everywhere all the time and if normal driving is the bulk of what you do the race car traits make them a PITA . The later GSR Evos get a bit more civilised but you're never going to turn a Cheetah into a family cat . My first impressions of an Evo was the steering is really sharp and fast (ratio) . Brake feel is better than anything I'd driven before and this thing is really nimble , changes direction quickly and easily which is why they have the go cart feel .. It felt quite torquey for a 2 litre four but didn't quite have RB25 down low . The gearbox ratios are close 1-2-3 and you get the idea you'll be short changing - lots . When you get into an Evo occasionally they give the impression they're goading you on , c'mon give me gas bugger this tooling around . They beg you to zip round corners faster and zig zag through the traffic . Curiously a standard 4G63T wants to be worked and is generally reving higher than you think - part of the close box thing . Then after a while you start to ignore the race cart stuff and just wheel it around like any other traffic victim . THEN you start to notice the firmer suspension the griping seats and 50 gear changes between traffic lights , a small voice asks you if you really like this stuff just cruising from A to B . The missus isn't generally impressed with the seats and firm ride and the agro styling . The bottom line is many people don't like tamed down race car traits - even if they are performance enthusiasts . Perceived road car performance and real race car performance is hugely different and not just with leaving rubber on the road . If you really do like race car like traits and a few civilised bits like music aircon fast glass and number plates Evos are great things . They are fast for production road cars and if you like acceleration they'll destroy any vaguely legal RWD Skyline out of the blocks . If you like bashing into you doors round Ss the Skyline hasn't got a hope of staying with you . BUT the Skylines seats are more comfortable they ride better and the RB is smoother and torquier at lowish revs . The gearing better suits general driving and they are a more relaxed overall package . The bottom line I think is you strap an Evo on where you climb in sit down with a Skyline . The Evo becomes more of an extension of your hands and feet so you have to concentrate more on what your new limbs are doing . It's not quite the same with the Skyline but you don't always need it to be . Different . A .

Personal opinion based on the force is that these GT30/35 IW housings are expensive to make and make Garretts GT BB IW turbos expensinve/hard to market . Note lots of suppliers quoting turbo price minus turbine housing . Maybe the huge American market thinks they'll get away with ext gates on road cars ... It's been a while since people put much thought into Garrett's older GT3071R and I always though a lot of its problem was the plain non shrouded comp housing . Some boost and surge related problems are avoided with port shrouding . Think for a minute about say a GT3076R/GT3037S with a HKS 0.61AR turbine housing on it , they didn't tend to have surge or boost control issues - the power delivery was light switch . Anyway for whatever reason 3071Rs were never a fantastic unit , never seemed to match the 2835 Pro S which used the same compressor and housing size - plus port shrouding . I think all GTX turbos have port shrouded compressor housings and HKS went to the trouble and expense of having their own made if Garrett didn't have anything suitable . No business does that without a justifiable reason . Also something I think people need to think more about with turbine hosing size is why there even is a range or choice . Its not just about how much exhaust flow you can get through the poor old turbine and what the absolute power number will be just before the rods go into orbit . Its about having the compressor spinning fast enough to make power where you want it in your engines rev range . Turbochargers are not perfect things , a radial inflow turbine at one end and a rotary air pump at the other . Neither turbine or compressor performance is linear and making a hopefully small system restriction in your engines exhaust creates other issues too . There is no perfect hair dryer . I don't like going out on a limb because opinions are subjective but ... Obviously with this GTX3067R you have to spin its compressor fast enough to shove enough air down 25s throat to make positive pressure . You have to have enough exhaust gas energy to spin Mr GT30 fast enough to make the compressor boost , and aside from the throttle your foots attached to the only other means of dialling in exhaust energy to boost threshold ask is T housing AR options . Now something else to think about is that were are having past opinions on GT compressor antics and basing some opinions on what we predict GTX ones will do . Most realise that the Xs pump lots of air and have better high pressure performance than the GTs do - BUT you have to spin them fast enough to get the best performance out of them . Uncharted waters . We know some people had issues with GT3071Rs GT3076Rs and 0.63AR GT30 IW turbine housings . The 76R has port shrouding where the 71R doesn't and the 76s don't surge AFAIK in this form . You probably get a lower detonation threshold on petrol but boost issues I don't know about esp with the later larger waste gate flap . To me it's pretty obvious that you have to spin lil X67 a fair bit faster than 76mm 56T GT to get 500 odd Hp's worth of air out the compressor housing and at 0.82AR T housing size that's probably a big ask with an 84 trim GT30 turbine . Especially if you want it to do something on a 2500cc engine at a bit over 3000 revs . I reckon if you aren't going to spin GTX67 fast enough to run mid 20s boost levels then you probably aren't gonna get 500 Hp or need 500 horse powers worth of exhaust flow capacity . So , with the mass exhaust flow down a bit the only way to get the turbine response up is to increase the velocity of the available exhaust gas by using a smaller volute passage . Real world I can only repeat what I've read from others using these turbos , response is good boost control seems good and they don't get compressor surge . This is with a 0.63 AR IW turbine housing . What happens with GT3071Rs GT3076Rs etc is irrelevant because the GTX67 compressor and T04B compressor housing are different animals , apples to pineapples . Different sizes mass and speed ranges/speed matches . A .

If I've got this right the car previously claimed 300 RWKW and the turbo has a 0.50 AR compressor housing on it . From memory only two Garrett turbos used a 0.50 compressor housing and they were the GT3071R and the XR6 turbos , GT3582R or GT3576R . From numbers people throw up here I suspect its got an XR6 turbo if it really did wheel out 300 Kw and it wasn't just the "sales pitch" . That number doesn't sound likely from a GT3071R . If money was no object and you wanted to run a high mount ext gate turbo then twin T4 is probably the go . With twin scroll big housings are supposed to be the go and 1.06 is I think as big as Garretts T3 and T4 housings get . Personally I think some financial sanity has to prevail with these things and if a bolt on GT3076HTA does real well on PULP and alcahole then why look further . On Neo Poncams , at least one person I know has the B type and wished they had the milder A type . If I had to change cams I'd go the mild ones . RB30 torque is what everybody wants so they can make a nice 300 at the wheels . A fair bit of work to gain 500 revs but the only other way is to use smaller turbos and compromise the top end . A .

Yes I'd like to know the Neo set up too . I'm not sure if there is a perfect RB25 setup , an RB30 in a lesser state of tune ie same 260 odd RWKW must be real flat and almost V8 like . Actually thinking about it Mr Mafia always reckoned his power delivery was almost V8 like and his R33 RB25 had a 0.63 GT3076R on it . A .

In my previous post I was disagreeing with the black art bit . To be fair it was always going to be a choice of 0.63 or 0.82 turbine housing on this turbo , and the majority of GT30 turbos . This turbo was always going to be a GT28 based one that grew an optional GT30 turbine so there's something in that . Most know that there doesn't appear to be much flow difference (if you can believe the turbine maps) between a 0.86 GT28 and a 0.63 GT30 hot side . Now the two litre four cylinder people worked out ages ago that the GT28 0.86 housing wasn't much of an upgrade on their GT28XXR turbos , I think a higher boost threshold and nothing earth shattering up high . I have read a few accounts of people going from 2867s to 3067s and one about a feller going from a GT3071 to a GTX3067 , they all used the 0.63 AR turbine housing . The feeling was that the 3067 had just a tad more lag than a 2867 and then better off everywhere , the GT3067 was said to spool earlier and be as good or better everywhere than the GT3071R . I don't think Garrett marketed the GTX3067R very well which is silly because the only variables with them are turbine housings and actuators . The 2L four cylinder people were obviously on the right track with the 0.63 T housing and it's a flow improvement over the usual 0.64 AR GT28 hot side , I wouldn't have gone past a 0.63 housing with this turbo on a 2L four either . The playing field changes with 2.5 litres and six cylinders because these makes more engine only torque and need more air to fill their lungs and make positive pressure . With no info to go on you can debate either way which T housing size should be better but in the end only trying both tells the story . As I said based on just a few accounts from people with 2L fours the 0.63 seems to work pretty good . All I can suggest is do the leak tests and then strongly consider a higher rated waste gate actuator , I opted for a 1 Bar big can version and had a pretty good idea that my 0.82 housing wasn't going to give early rapid boost rise so better boost control loaded up . If leak fixes plus the actuator don't help and the tune and exhaust aren't letting you down then it's pointing towards the turbine housing not giving high enough gas speed through the turbine to spin the compressor fast enough early enough . The common ground with positive GTX3067R results seems to be the 0.63 housing , someone was always going to go larger to see what would happen and I'm genuinely sorry if I gave you reason to think it'd be the go . With a bit of fault finding and possibly a 63 housing your results can only get better IMO . Intercooler wise I made 271 wheel wasps with a smaller GT28 turbo admittedly on E70 but if the Blitz return flow had been a major restriction ethanol wouldn't have made the situation any better . A .

I don't agree with your viewpoint but at the end of the day engineers and manufactures have to try everything real world to get a real result , then move things around a little to dial in their desired result . I think in this case the consensus view was to treat the 0.63 housing with suspicion because they don't always suit peoples likes on GT30s with larger compressors and housings . Units like GTX3071Rs and GT/X 3076Rs are going to have higher pumping capacities and higher tips speeds and the 0.63 housing can be a bit marginal on flow once those compressors are run towards their limits . It might be interesting to compare the lower compressor flow rates and wheel speeds to see how the GTX67 compressor compares . To my way of thinking if your getting positive pressure at low revs in high gears that sez that greater throttle opening is probably sending more exhaust pulse energy down the line to the turbine and getting it going . The same engine revs in lower gears divides the engine load by the gear ratio reductions so the throttle opening is often less meaning throttle dampened exhaust pulse energy . A smaller AR turbine housing will increase the exhaust gas velocity through the turbine blades everywhere and in theory spin the turbine faster lowering the boost threshold across the throttle/load/rev range . I'm sure if you changed to a 0.63AR IW turbine housing (direct exchange) and liked it the 0.82 one would be easy to sell because these housings are a considerable part of a complete turbos price . Or , if you decided later to use a larger GT30 turbo it's cheaper to buy and add your own housing . Just on this when last at GCG they told me Garrett is keen to ditch these IW GT30/35 T3 housings because larger markets are opting for external gates and V band fittings . Don't know how long stock will last so maybe check availability with your supplier , cheers A .

I think GTRs are going to be a bit more expensive to live with than Evos and harder to work on . People are right on the weight/capacity thing in later performance cars and XR6s are a prime example . Getting a smooth flexible 300 engine wasps from a Typehoon is really easy in todays emissions/consumption world . They're going to make lots more torque off boost and not need anything like the state of tune that an RB25's going to take to achieve it . They're going to be able to pull taller gearing and have higher speeds in the gears which IMO is lacking in a Skyline 1st to 4th . Just think what a GTS25T would have been like with an RB30 and around 250 Kw , could have had a 3.7 or 3.9 diff and a taller 1st gear . The Typhoon engine has variable cam timing on one if not both cams and that makes a difference too . Throw that at a 250 engine Kw RB30DET and it would be really smooth and flexible with todays control electronics and injectors . I don't know if the rear suspension would be that different in a retro R33 but you can be sure it wouldn't have 16 inch wheels and I assume 225 tyres or whatever they had standard . The diff would possibly have had a Torsen - did later GTts have those ? My latest rear tyres are Pilot Sport 2s in 255 40 17s and while I don't hoon around they feel better planted than the 245 45 PS3s they replaced . If I was going inside the diff I'd want a taller ratio and a real LSD of some kind , taller diff for a bit more speed in the lower gears particularly that uselessly low 1st . I run cradle bushes and the SK Whiteline Bilstein suspension with fresh dampers . OT I know but is there a 3.9 that bolts into a non ABS GTS25T , maybe something from an S14 ? A .

I think to understand Evo hype you have to live with one for a while because a lot of what they are isn't immediately apparent . I think I mentioned earlier that 2.5L is always going to feel a bit better than 2L just to wheel it around . Also there is a certain something that straight 6s have that straight 4s don't , by comparison 120 degree phasing feels smoother and more flexible than 180 degree phasing . Note that inline 3s are making a come back and they are effectively half an I6 with ~ 25% less parts than an I4 . Once you feel out an Evo it feels far more go cart like than a Skyline because it has sharper faster steering and less slop in the bushes - factory . They are shorter wheel base wise and not sure about track width - probably similar . I sense some people think that a fun car has to have limited handling abilities and 4/AWD is somehow unfair , the V8 taxi racers though that too back in the Grp A days funnily enough . This is where the big "lurid" power slides spinning wheels and drift mentality leave me cold . The rally people told me that AWD solves some problems and creates others , it totally alters any cars handling characteristics and holding them on the limit isn't generally something your average driver can do . GTR is a totally different concept because they aren't AWD they are front assist to RWD to give them RWD characteristics . What is similar with driving all four is that the limits are higher and that's why the crashes near the limit are monumental . Gearing , yes they have closer gearing 123 than a Skyline because that's what makes them haul out of the blocks and helps them to make quick gear changes . It is more awkward to pedal around Camry like in the traffic but you can't have it both ways . It wouldn't be any better in a Skyline with a close ratio box driven the same , it's highly likely that Nissan knew closer spaced gears would mean spinning longer in more gears than they do . Obviously you stop spinning when 2.5Ls finds a gear it can't muscle enough to do so . What is better with the Evo is that you have 1360 + Kg on the driving wheels rather than sub 650 on half as many contact patches . Because their tractive effort is higher they can afford to have closer spaced gearing because they will put all of their power to the ground in std form - with reasonably good tyres . I don't know cabin wise much about E7/8/9 because mine is a slightly smaller E6 , interior styling is an individual liker/dislike thing and some people used to Skylines may not like an Evos cockpit . I guess the bottom line is that Evos have higher limits than a GTS25T or 34GTt but in order to have them there are some inescapable compromises , it's why a real race car would be the worst thing to drive on the street if that were possible . Evos are just the next step towards a real racer , but with number plates and 5-10 years newer systems . Being less race oriented is what makes a Skyline a bit nicer to live with . A .

My take , and I have a 33 and an Evo 6 is that the Evos will put more of their available power to the ground a lot longer than most/any RWD will/can . It comes down to 100% of the weight on the driving wheels so they hook up and scram most of the time . Honestly for round town "normal" driving I prefer the Skyline but it's probably because 2.5 litres is a bit more torquey and flexible than a rock stock 99 mod 4G63T engine pulling around the same mass . Powered up and driven flat footed the Evo would eat the Skyline partly because of traction/brakes/gearing and they're a much more nimble car than an R33 anyway . Where this is fun on the street is you can get them up and cracking quickly and pull the speed back down equally as quicky to avoid notice . Also you don't have to have screetching tyres and clouds of smoke to leap out of the blocks . I think the best way I can put it is that Skylines , exc GTRs , are better all round cars where Evos are a bit more narrow focused - biased towards performance and handling rather than being a nice relaxed cruiser GT car . A .

Or when the bypass hole in the standard one isn't large enough to stop fuel pressure rising at light loads and idle with higher volume pumps . In theory any reg can close right up but standard ones can only open up so much . A .

My 33 got 271 wheel wasps with the same intercooler , Insights Dyno , and that apparently is what the limit of a GTRS (HKS GT2871R 52T) was with Eflex E70 on my car . It got to 17 pounds of boost and falling to 14 up high . Hopefully back on the rollers in a few weeks to see what difference a 3076 and a better exhaust makes . Also doing a top feed conversion and a different reg and possibly pump . Now that I can get E85 I may change to that for a few more giggles , hate exhaust soot and ULP stink . If these Blitz return flows are a limitation I'll soon find out . The reason I mentioned GT3071Rs above was because of the dramas people had with turbine housing choice . I thought they found waste gating issues with the 0.63 and so so response with the 0.82 AR one . May be interesting to read their findings . A .

It is a bit harder with new turbos because their characteristics are unknown . You are the first I know of to use a 0.82 housing on this turbo and it may pay you to look at results for GT3071Rs on RB25s . I remember there being mixed results on those with 0.63 and 0.82 turbine housings and I'm not sure if there was a solid fix . I searched around when they first came out because the hype at the time was much better response than a GT3076R but they never seemed to really achieve that . I have read accounts of people replacing them with GT3067Rs and getting better all round results but this is on 2L fours and with the 0.63 turbine housing . I think the worst case scenario is changing the 0.82 housing and I'd only do that after fixing any other issues ie actuators . My experience is that you have to have an effective exhaust if you think the turbine housing is borderline big , it worked on my 33 so if you have any known restrictions do something about them . Also do you have any way of checking the tune settings because I'm interested to know where the ignition timing is at lighter loads . A .

Time will tell , if the turbine response is adequate then the larger housing will pay off in other areas . One is exhaust heat and pressure which often leads to detonation . You would think that with a less detonation tolerant fuel like P98 a bit more boost and and a bit less exhaust restriction will make more power . Assuming the tuners do a good job with the light load low end areas the "torque crossover" of engine only to boosted performance should be acceptable .

In theory , notice how the gas flow increase never seemed as good with an AR change in a GT28 housing as it does in a GT30 one . Not sure if it's of any benefit but I seem to remember GTiR T28s having a 79 trim turbine that may have been similar to the GT28 NS111 but with 10 blades .

Just on the GT2871R 56T vs GT3071R 56T , the compressor housing families are different . T04B 0.60 AR on the 28 series and T04E 0.50AR on the 30 (cropped and full) . The HKS GTRS and GT2835 Pro (cropped GT3071R 56T) pretty much same but port shrouded comp covers in most cases . My take on GT30 hot sides on RB25s is more flow , the engine makes more torque down low off boost because it's a more efficient piston pump . You get back most of anything you lost from early boost by advancing the timing . The GTRS by comparison made usable boost earlier but the engine was never as free spinning as with the 30 series . I think the hard thing to explain to someone that hasn't tried a decent spec GT30 is that you get real good drivability and part throttle torque but real shove in the back comes at higher revs than with a 28 series , it's mainly the full bore (throttle) performance that moves up the rev range . I've only had a 0.82 AR turbine housing so I don't know how the 0.63AR directly compares back to back . I'm going to assume that Garrett's standard spec GTX3067R had the 0.63AR turbine housing because they though the smaller diameter 67mm compressor needed a few more revs to make boost in the lower mid range . I also think they may have aimed these turbos at people with 1800-2400cc four cylinders and sized the turbine housing to make them come alive in the 2500-3000 rev area . Some of the builds with GTX2867Rs make good numbers but somewhere between having a marginal turbine for a 500 Hp compressor and pushing things exhaust flow wise make a bigger turbine a better match overall . 28 series are logical bolt on upgrades for CAs and SRs but RB25s need larger flow paths than GT28 turbine housings have - even the HKS T3 flanged GT28 ones . I suppose once you get more serious with a CA or SR you'd go for a T3 flanged exhaust manifold and this IW turbo would be a good all rounder on the street . Said to be a better package than a GT3071R and more compact too . Win Win . The 3067R should be a very streetable unit on an RB25 and the 82 housing will give you low exhaust side restriction , it should allow fairly advanced light to moderate load timing and on boost it should be good in this area if the exhaust and intercooling is effective . The thing it may not do is give high dyno numbers compared to larger GT30s but at the end of the day if it's free spinning (engine not car) and struggles to gain traction with the boot in who cares . A .

Roughly 500cc cylinders in a 2 litre four compared to ~ 415 in a 2.5 litre six .

Yep waiting for this result because it's the first line in the sand with an RB25 . It will give an idea how this turbo runs with an 82 turbine housing and I'm curious to know if it gives high enough gas speed to make meaningful boost in the lower mid range . Like Lithium I'm wondering about wheel speed on slightly smaller diameter compressors . I could wish for a slightly larger GTX compressor and just a smidge larger compressor housing like say a T04B 0.70 AR . These housings you generally don't see in performance petrol turbos though I suspect Hypergear is using a version of them in some of their larger Hi Flows . They have the large diameter inlet boss so it should be possible to machine the port shrouding into them like Garrett does on the 60-67mm GTX T04B 0.60 AR housings . I know I'm using the force here but I reckon there's more to the 10 odd pounds airflow difference between a GTX3067 and a GTX3071 than meets the eye . Using the same turbine housing ie 0.82 AR IW evens the hot side but I wonder if one of Tao's comp housings would help close up the cold side potential . Just as a heads up Garrett generally uses the large inlet boss and 2.5 inch comp housing outlets on their larger 0.70 AR housings , they do on the T04B T04E and T04S ones mostly anyway . You can buy the Garrett T04B 0.70 AR comp housing but it comes machined for a larger inducer wheel than a GTX 67 so not a bolt for the wheel anyway . AFAIK it uses the same T04 backplate adapter ring for the Garrett GT BB cartridge . I'm sure Tao has it worked out , cheers A .

I figure if an Evo TD0516G can do 206 kw two may work in the right housings . To make a GTX67 with the 90 trim cropped turbines it's probably easier to start with a 2867 cartridge and exchange turbines . If you're going to use GTRS comp housings make sure you get cartridges with the 52T 71mm GT compressor because that what GTRSs have . A .