discopotato03

Yes I agree , I wouldn't be reaching for higher performance cams if you wanted to pull the lower mid range up . If you really need the head off it probably wouldn't hurt to smooth the ports a little and blend everything in nicely around the valve seats . You could possibly smooth up the insides of the exhaust manifolds not to make them larger but to cut down any avoidable boundary layer flow losses . I personally think an RB26 can use a bit more than 8.5 to 1 static CR so you could have the head decked but watch piston the valve clearances . Good cam gears and a bit of playing around with the standard cams timing can probably gain you a bit easily enough . What are you doing with computers and tuning > A .

If someone can find you a cam chart that shows the opening and closing positions of the valves and how the inlet and exhaust open periods compare . Note that with cam and therefore valve timing all numbers relate to crankshaft degrees except lobe center lines . Its done this way to relate valve timing to piston position ie when inlet valves start to open just before top dead center at the tail end of the exhaust stroke and going into the induction or inlet stroke . Both sets of valves are generally always open for longer than the full inlet stroke or the full exhaust stroke and this makes it easy to work the full duration out from a cam chart or the advertised valve timing numbers . Say for example the inlet numbers are 10-56 and the exhaust are 56-10 , this tells you that the inlet valves open 10 degrees before top dead center (BTDC) and close 56 degrees after bottom dead center (ABDC) . Now we know from top to bottom dead center has to be 180 crankshaft degrees so you add the BTDC number to the ABDC number and add 180 to get 246 degrees inlet valve duration . For the exhaust its the same deal though its a rising rather than a falling piston stroke so they would be opening 56 degrees before bottom dead center (BBDC) and closing 10 degrees after top dead center (ATDC) . The overlap is simply the two smaller numbers ie 10 + 10 added together because it represents the number of crankshaft degrees where the inlets are opening before top dead center (BTDC) and the exhausts are closing just after top dead center (ATDC) so in my example is 10 before plus 10 after to give 20 degrees overlap . Don't be spooked by the TDC and BDC because all they mean is the piston at the very top of its stroke or the very bottom of its stroke . You can have a "B" or an "A" infront of either of the TDC or BDC and all that indicates is that the valve opening or closing events occur before (B) or after (A) top or bottom dead center positions . The give away that cams are getting hotter is that overlap figure gets wider or numerically bigger and usually that's when the idle and low speed power suffers because the low speed trapping efficiency of the cylinders is compromised to make breathing improvements at the upper end of the rev range . Now your call but I look at cams and turbos is a simalar way , go just that little bit too far and you lose the normal drive around power thats important on the street . My experience is that people who are conservative are disapointed less often than those who got a bit hungry and thought they could live with too much cam and or turbo . Also its important to realise that multi throttle inlet systems like those on GTRs and GTiR's can use hotter cams and not get the reversion or choppy running at low revs as much , its because closed or nearly throttle plates physically block reversion waves that would ordinarily bounce around together in a single plenum and throttle type inlet manifold on an RB20/RB25/RB30E/ET . A .

There is one in a clear plastic bottle called Car Go Metalic Seal Up , search the web and its available through Ripco and Super Heap for ~ $11 . I have used it for a cracked head and can vouch that in a rebuilt lowish Km engine it didn't clog radiators or damage thermostats or water pump seals . This was a flat fours aluminium head BTW . A .

I think the pertinent thing is what the running oil temperatures are and obviously in a track situation it will be higher in an engine without improved water and oil cooling systems . I know of people who club raced RBs and used 10W60 oils all the time , they freely admitted that they could have had better road fuel consumption and a bit more power on the street because of lower viscocity oils reduced oil sheer drag . Personally I think the best of both worlds is to use a thermostactically controlled oil cooler system and slightly lower viscosity oils . The oil thermostat is there to make sure the oil cooler does zip until it reaches a certain point ie 90-100 deg C . The say 10W40 oil lubricates with less drag and the oil cooler keeps it from overheating when worked hard . Just as a heads up GL Lubricants in Sydney is bringing in some of the various Mobil 1 oils not normally sold in Australia and the ones that interest me are the synthetic 4T Racing bike oils . I've used this in 15W50 and while I've had no issues with it I'll change to the 10W40 viscosity when it becomes available soon . These 4T Racing synthetics are not dedicated race oils but they are very high in ZDDP or Zinc and Phos which are anti wear additives fast disapearing in many current "Green Era" oils because they poison Cats over time . From memory the pricing will be around 12-13 a quart and available also in 6 quart cartons . Food for thought , cheers A .

I see this as a bit of a curiosity and it is mildly interesting but it raises a few points . 1) If you want a turbo engine to start boosting earlier why use a GT42 based turbocharger . 2) RWD platform so traction limited , why chase power beyond traction ? 3) We all know biggest is often far from bestest so why encourage people to supersize turbos in the first place ? I think a properly proportioned TS twin gate system would work better overall because its not part time limiting the exhaust throughput so the engines tune could be better in the mid range . I get the feeling that that car would be a handfull to drive and difficult to modulate power in the real world . I also think turbos of that size on a 3L based engine are getting a bit wild and really dyno comp/dyno queen material . Ultimately a properly designed twin integral gate twin scroll turbocharger with light weight internals is a better bet and EFR appear to have gone that way . Just need "TS T3" flanged versions to keep the bolt up brigade happy . A .

Boostage I know the numbers may look similar but there is every chance that turbos developed to be responsive in parallel on an I6 were changed because existings ones proved not to be as suitable . I too once wondered if the slight differences in the -9s compressor was that much different to a 60mm 50 something trim wheel but Garrett and HKS must have thought so because they went to the effort and expense to fit and test that comp wheel . Just on this there is more to a compressor wheel than its blade count , inducer and exducer diameters . The exducer tip hight (sometimes called tip width) is another variable and it can make a big difference to a compressor wheel/housing combinations performance . If you look at the GT2860RS turbos you notice a difference in this tip height with the versions intended to be used as twins . I'll have to double check but from memory the single turbo SR style GT2860RS uses cartridge number 446179-66 where the other similar unit uses cartridge number 446179-56 . Almost identicical cartridges inc their comp wheels inducer/exducer/trim sizes but the tip height IS different as is the cart'number . Turbines in the case of the two you mentioned are totally different wheel families not just one kind with a slightly smaller OD option . The TB25 62T is ~ 0.8 mm smaller in the OD than the NS111 53.8mm 62T wheel and its exducer is slightly larger as well being a trim size of 53.8 rather than 53mm . I can't say what the turbine wheels tips heights differences would be though I do know for a fact that NS111 turbines were designed to be lightweight high speed performance turbines where the TB25 is a carry over from the TB25 family and an OE responce kind of thing . The NS111s are 9 bladed vs the TB25s 11 and thin curved trailing edged blades - lighter by the look of them . Housings on OE parallel twins are generally smaller than those on single units because they have less cylinders and cubic inches trying to kick them into life . I'd say if you had a four litre 6 and wanted low end boost then sure maybe use two SR turbos but you I think have 2.5 litres and only half of that driving each turbo . I believe it really is a juggle sizing twin parallel turbos because you have to have the turbine/housing combination sized right to spin everything up in the appropriate engine speed ranges , the compressors have to be a good match load and pumping capacity wise for the turbines and the engine , AND you want to avoid excessive turbine inlet pressure and compressor surge . With so many things to juggle its a lot to hope for that using turbos designed for a different engine configuration will work . Maybe they will and maybe they won't and if they don't you've spent the money and your turbos are "used" so drop in value . Honestly what I'm trying to get you to avoid is the pain involved in getting it wrong because if you then have to buy the right turbos its expensive particularly with two of them - AND the work involved to fit differently packaged turbochargers . Anyway as I said I'd err on side of caution with the R34 GTR BB turbos if they have steel turbines or the 707160-9 ones because both are known to respond well twinned on a 2568cc I6 . They are a known quantity rather than a guestimate which if you're unlucky will burn you big time money wise . Ultimately the decision is yours and its your money at stake . Too late now but another option if you kept the original bush bearing turbos may have been to have bought BB cartridges and had them modify and reuse your old housings . Again your call , cheers A .

Well that changes things a fair bit . Different engine with different manifolds and high mounted . I suppose the pertinent things are the different inlet system and a little less capacity . My approach would again be to look at how much capacity is driving each turbine and pay a bit more attention to the compressor sides because they can have considerable effects on turbine response . Now four cylinder engines are different particularly with the one single scroll turbocharger , they have in 2 liter form have four 500cc pots sticking it up the turbine every 180 crankshaft degrees . A twin turbo (parallel) 2.5 liter six has 1.25 liters and three 417cc pots to feed each turbo with . These differences are the reasons why parallel twins are smaller and configured differently to four cylinder singles . I'll go a bit into OE SR20 turbos so you can see the differences . Firstly the -1 OE SR turbo is the S14 variant , the -4 one was the S15 BB variant and is more expensive because of its higher material spec turbine and turbine housing . Now these SR turbos both use the TB25 turbine because from a gas energy perspective would be the most responsive . The compressor side uses a 60mm 60 trim GT series wheel in what is basically a Nissan restyled T04B compressor housing . Now something you have to remember is that turbo engines do ALL their breathing through their compressor housing/s so they must pass sufficient air with least restriction to feed the engine in a non boosted state . I believe there is a juggle with having it do this but still be suitable for the compressor wheel/s and air speed when the turbos up and running . Did you notice how the OE RB26 turbos have what looks to be small (0.42 ?) A/R compressor housings and T3 internally rather than T4 . This is an area where using four cylinder turbos may not pay off on a six like yours . I know peoplw will say that some of the higher performance GT2860R BB twins intended for GTR's use the larger comp housings and compressors but they are 330+ Hp turbos on engines looking for high rev performance . They also use the largest size and trim turbine which kills any chance of low end squirt . I'm not really sure what kind of power delivery you want but I tread warily with an unknown quantity like a 1JZ that never had parallel twins or those manifolds standard . I'd research things like the OE BB turbos used on R34 GTR's which from memory were a GT2556R , I just can't remember if their turbines were ceramic or Inconel steel alloy . There may be the opportunity to buy these turbos second hand but thats always a grey area with turbochargers because its hard to know what sort of lives they've had . I'm not sure if I've helped you much , I just know that manufacturers spend a lot of money developing these systems and they don't change things for applications like yours for no reason . This is why I'd be wary of using those SR turbos on your engine and look closer at what they do with parallel twins in a factory application like an RB26 . Cheers A .

Well as I keep saying I'm not a GTR person but those that are always reckoned that RB26 style HKS GT2530s work pretty well on a GTR , provided you don't expect them to spool up any sooner than std turbos . I reckon you could do worse than to use these turbos on a 2630 because you know they are direct fit and the difference is that they may come on ~ 15% earlier with an extra 400cc's driving them . There really is a lot of money tied up in single turbo conversions and its a real downer if it does not meet your expectations . A .

Really shitty ATM , lost a detailed post explaining about the differences of the OPs linked turbos in his original post . Brief version . The GT2560R you linked is one of two almost identical OE turbos for SR20DETs . 446541-1 and 446541-4 and the difference is the -4 has a higher temp spec turbine and turbine housing . The more temperature resistant version costs more to make and to buy . All the GT28 ball bearing based aftermarket turbos Garrett make for RB26's use the better materials and that would make them more expensive to buy than a lesser temp spec GT2560R . Probably the best way for anyone to prove to themselves that SR style turbos wouldnt fit is to painstakingly remove the std RB26's turbos and compare them to SR ones on the bench . That way you'll realise why such customisation was needed in the first place for Nissan to get twin parallel turbos on an RB head . The other sad thing about RB26's and GTRs is that because so much of the both is unique that rarely does cost cutting come into it . They are such a complex and time consuming thing to pull apart and put back together that few want to risk scrimping on bits and have to go through the whole painfull exercise twice if it doesn't work . Your call , I'd just get the best new price for -9 turbos and do everything to the engine at the same time . Do it once do it properly and have piece of mind for a long time . Expensive ? Yes but then thats the nature of doing virtually anything to a Skyline GTR and probably the the main reason why I wouldn't own one . An Evolution Lancer by comparison is a piece of cake by comparison but thats another non related story . Cheers A .

Giz a tick , I have to have a look back through my Garrett notes because my head is full of Misty turbo stuff ATM . A .

I've been asked to stick my ore in which I don't mind doing because the topic interests me but always remrmber that I'm not a Skyline GTR person for my own reasons . That said , I see an RB26 in a GTR Skyline as a very different turbo application compared to just about anything else of that era . You can't realy draw a direct comparison between the turbos suitable for RB26 twins and other single apps ie CA18 SR20 etc etc . I know they both use the same T25 style mounting flange but the packaging constraints for the two original T28s means things had to be altered to get them on the head and into an R32s engine bay . The chief differences externally are RB26 specific turbine housings which are designed to be more compact than the CA/SR type T/GT 25/28 housings . Because these 4 and 6 cylinder engines package their turbo systems differently they can't have a turbine housing style that suits both mainly because the twins on RB26's had to be all close and cuddly , I supppose , so the body could be a drop on/over process on Nissans production lines . The bottom line is they are different applications and there is no advantages and major disadvantages in trying to interchange the two turbine housing styles . Now the compressor housing styles are again different for packaging reasons and unless for some reason you were doing customised plumbing , for whatever reason , I can't see why you wouldn't use an optional turbocharger thats designed to be a direct fit for your specific engines application . I strongly doubt there is the opportunity to save money because by the time you fabricate all the bits around the turbo you've burnt considerable time and money . Now to the controvercial part , please exc spelling , checker not working and I'm struggling with a chest infection ATM so oxygen is a premium ... People have their own views on what a well developed performance car drives like from a power delivery perspective , I like an engine thats free spinning but it HAS to make acceptable part throttle torque and I won't be waiting all day for it to happen . I HATE engines that have no usefull pulling power and you have to buzz the engine around at higher than normal revs so that when you want it to go it will , useless for a middle aged person like me on the street . While I'm being critical I DON"T belive short gearing is the answer nor that lack of low down squirt is foreplay . I take the practical approach that a road car has to drive well whout have its kneck rung ALL the time . Basics , an R32 GTR weighs approximately 1480 Kg so I be nasty and round that to 1500 or a tonne and a half . What lived under the lid is a 2568cc 8.5 to 1 compression ratio inline six cylinder engine . Its not really a lot of capacity or even an adequate compression ratio when it comes to moving a tonne and a half from rest . I don't know for sure but I reckon if you took the actuator rods off you waste gates valves A GTR wouldn't be mega exciting . What this means is that they don't make the sort of torque particularly at around town revs that make cars feel nice , IMO anyway . So we get to the hair dryers because we need more air that the atmosphere can push by itself to make some worthwhile grunt . The factory T28 turbos really don't set the world on fire until we get into the buzz the engine type revs and considering RB26's were intended to be a homologation road race engine that not terribly surprising . RS500 Sierras were the same and I'm sure many other manufactures road going homologation specials were too . Off the top of my head I believe the early Grp A R32 GTR could make something like 600 650 Hp but I'm not sure what the boost levels or revs that was at - or even if the turbos had air restrictors on them at the time or what size they were . At 2.568 Litres and 650 Hp your talking about 253 Hp/L which is not bad going though admittedly they were not using base R32 turbos cams etc . They were using 2568ccs and it would have been an interesting prospect trying to tone such an engine down to something you could legally make and sell in a road car in 1989 . The trouble is that there is a huge divide between a road car and a race car and even the road car basis of what works in a GT Tarmac racer won't be a 6L Chev down low because the process of making the engine have big breathing potential has to cost it torque down low at the sorts of gas speeds a road car normally uses when driven at sane speeds . Now to GTR road cars and what has the potential to make the car nice on the street - in my opion . I will go to the grave believing torque is everything and when you have enough of it and the control over the engine to make it deliver it smoothly and controllably it just doesn't get any better . I also believe that torque/power beyond traction is absolutely useless in a street driven car , why anyone would seek more or live with an engine in the state of tune that throws away the bottom end and lack of traction can't harness the top end is a mystery to me . If I was suddenly rich beyond belief and inherited a GTR Skyline it would have 707169-9/GTSS turbos on it end of story . They help the engine make more torque at lower revs than the std , bush bearing anyway , turbos do and have a far more durable bearing system in them too . You give away the potentially unreliable ceramic turbines of the early factory T28's so it takes the form of a win all the way down the line . More torque lower , more longevity , a bit more mid range torque and top end as well I'd reckon . Now I suppose half the people reading this are gonna say bullshit those tiny whissers are going to run out of puff and won't hold 50 pounds of boost to 8000 revs and they would be right . Where down the road can you drive like that without the riot squad pointing shot guns at you ? Anyway a good spread of torque and some exciting mid range squirt is what make a good road car for me and I don't think this idea is lost on mobs like HKS . They obviously sat down with Garrett Japan and spent some time developing bolt on turbos that were a win everywhere over the factory ones . For those that wanted more performance and could accept the std lack of performance down low they developed the 2530's which technically are a GT2860R variant in Garretts current terminology . Now to the innards for the propeller heads though I think I'm repeating what I typed out last year in one of these GTSS/707160-9 threads . There are three turbine wheels use in Garretts GT25/GT28 family of turbochargers and thats forgetting for a tick the material spec . The smallest one measures from memory 54mm in 62 trim and I think its actually a carry over from the TB25 turbos but having the shaft dimensions to suit a GT25BB center section . Its what the bush and ball bearing SR20 turbos use though in the S15 spec SR20 they are made of higher temp spec material as is the turbine housing . The turbine housing you can tell by the vane around the turbines outlet and the material is a different colour/texture than the lower spec ones . These TB25 turbines you can tell to look at because they have more blades (11 from memory ?) and they have a kind of forward rake as their straight edge blades radiate out from the turbines hub at the rear . The next two larger capacity turbines appear to me to be the same thing but in two different trim sizes but to save confusion now I'll call them the mid and large capacity ones . The mid one is definitely a GT28 turbine because it measure 53.8mm and its also in 62 trim but has 9 swept back and curved trailing edged blades . Its the least common of these 3 turbines and that makes me think its a bit of a special brewed up by Garrett for the then HKS only turbo options . The large capacity one is of course the 53.8mm 76 trim GT28 NS111 turbine and it usually turns up in most of the high performance GT2860R and all GT2871R and GTRS turbos . HKS have them in the T25 flanged SR20 spec GTSS/all 2530's/all 2535's/all 2540's/all GTRS's . When looking at turbo specs look to the turbine dimensions because some are similar enough to go almost unnoticed . 1) The major diameter which will be 53mm or 53.8mm , the smaller being the TB25 turbine . 2) The trim size because like the basic TB25 turbine the smaller of the GT28 turbines is also 62 trim . If you see 76 trim then you know its the larger of the two GT28 turbines because AFAIK there is no 76T TB25 turbine . When you look at an RB26 with twin parallel turbochargers its plumbed on the exhaust port side like two three cylinder 1284cc engines because the hot side of each turbo is only fed by the front or rear three cylinders . Thats all the exhaust energy each turbine has to work with and this is critcal because the turbine is the turbochargers (compressors) ONLY power source . The turbine has to recover enough thermally excited and expanding exhaust gas to spin the compressor fast enough to positively charge the engines cylinders at an engine speed thats usefull . When you develope a race engine thats designed to have power at revs because the maximum performance is the goal you can size the turbines and their housings with less restriction in mind because no one races at part throttle or potters around the suburbs . A road car obviously isn't driven flat out everywhere and needs to have adequate performance in the sorts of engine and road speeds used most often . So HKS discovered that the TB25 turbine was the one best suited to making a GTR a better all round performer . They put them in a 0.64 A/R turbine housing which is this time one Garrett make to suit RB26 packaging . Don't quote me but I think this A/R size is a tad larger than the turbine housings used on std T28 GTR turbos but is not by much . From what I can tell the GTR T28 compressor housings are T3 dimensions internally and in an odd A/R size I can't remember ATM . I believe the GTSS ones are similar/same . The compressor wheel is probably the most interesting part of these 707160-9 turbos and from what I can tell is unique . I've never had one -9 turbos to measure up the tip height of these wheels but you can be sure HKS and Garrett went to a fair bit of trouble to make them work well on a road RB26 because they are afterall tailor made for RB26's and NOTHING else . They are not a generic Garrett turbo and its interesting that you can't seem to buy its cartridge separately and I did inquire a year or two back . There is actually a bush bearing I think GT20 turbo that also uses a 59.whatever mm compressor wheel but its in a different trim . Back at the GTR road car . Now I reckon you can make all sorts of incrimental improvements to RB26's without giving up any paultry low down squirt the things have std . I reckon you can gain a bit with porting and MILD cams and a bit higher CR wouldn't go astray with the fuels available today . Maybe smooth up and match the manifolds and fit proven dump and exhaust pipes and a low restriction cat . The beauty of building medium rev torquey engines is that NOTHING has to be big and the work involved can be quite straightforward you're basically enhancing what the factory spent the millions on producing . The things you MUST avoid is huge ports/big valves/huge manifolds/huge cams/and huge exhausts cause the engines only gonna break off and rattle down the pipe ... You have to remember that enhancing torque means having adequate air and exhaust gas velocity to make the engine volumetrically efficent and make strong torque without the huge increase in engine revs . Don't even bother trying to convince me that you can't make strong pulling power without a bootfull of revs because Mitsubishi , well Ralliart , cranked 650 Nm of torque out of their two liter four cylinder rally engines and did it under 5500 revs - with a turbo air restrictor . An RB26 should be easier because it has the extra nearly 600cc's and it isn't like an R32 weighs 25% more than say an Evo 6 GSR , 1360 and 1480 the numbers are from memory . The real power delivery differences are that one was designed to be the basis of a Group A Rally car and the other a Group A tarmac racer . It's old news that rally car power ranges are more closely aligned with road car power ranges than tarmac racers are because road and rally have to have power from lower engine speeds . This is really driven home with air restricted turbo race engines because the builders are forced to make best power , read torque , in a limited rev range and cieling . Anyaway if anyone is still awake I think its entirely possible to build an RB26 capable of maybe 330-350 kw and a real good spread of usable torque . You just have to remember that turbo/s are just one part of a system and if you keep that in mind and keep thinking torque rather than kw/hp and high revs then you'd end up with a pretty sharp roadie in a GTR . My opinions only , cheers A . A .

Actually I just noticed what looks the the oxygen sensor probe hole in the turbine housing so its possibly an FJ20ET 0.63 A/R turbine housing , I seem to remember VLs having it in their dump pipe . A .

Actually I just noticed what looks the the oxygen sensor probe hole in the turbine housing so its possibly an FJ20ET 0.63 A/R turbine housing , I seem to remember VLs having it in their dump pipe . A .

It would probably prefer the Hitachi BB VG30 turbos larger OP6 turbine housing if you can find one . From memory an RB30ET made 153 Kw from its 50 something comp trim small turbine series T3 turbo in 0.63A/R turbine housing form . An RB 25 with the above mentioned turbine housing made I think 206 fly Kw in an R34 GTt . A .

Don't trust my fallable memory because it could well be 100 and 80mm . All GT2835 Pro S turbos (AFAIK) used the -3 cartridge meaning the cropped 84 trim GT30 turbine and the 56 trim 71.1mm GT compressor wheel . I think other HKS variants used smaller trim compressors or the 90 trim turbine but not the Pro S one . A .

That "thing" , and I'm being nice , is the dreaded bastard hi flow bitzer turbo . The housings look a bit like RB20 on the compressor side and T3 on the hot side . The hub of the turbine looks a bit like a Hitach HT18S one . Probably bore everyone but . 1)Comp housing inlet bored out a lot so a big wheel for a smallish compressor housing . 2)Hitachi turbine big which is fine for a Ser 4/5 RX7 Rotary but iffy on a bastard hi flow . 3)Note the size of the waste gate outlet hole on the T3 turbine housing . Maybe Ok for a dinosaur 70s era 150 Kw T3 but not for any current (in the last 20 yrs) performance engine . I would rather run your engines std turbo if in good nick than that thing . A .

Everything I've seen suggests that standard RB25 and RB26 heads have the same config and volume in their chambers . Usually manufacturers take the easiest read cheapest changes to get what they want in production engines . By this I mean pistons are I'd reckon cheaper to change from suppliers than cylinder head castings so it makes sense to me anyway . My own opinion ? If possible change the static CR with pistons . I think different thickness headgaskets is a half assed way of changing things when its not intended to pull the engine out and do it properly . Thats fair enough for those on a budget but if is out and apart I reckon do it the way a good engine builder would and that means the appropriate pistons and an OE thickness headgasket . The fact that its an RB25 head and generally a single throttle inlet system means IMO that 8.5 is too low . If it was running a 26 head/inlet manifold/cams then 8.5 is probably Ok . The big difference with multiple throttles is you have far less resistance to inlet flow and the dynamic or effective compression ratio tends to be closer to the measure compression ratio . Nissan raised the static CR on RB25's because they knew the dynamic CR would be lower off boost and they wanted a bit more part throttle torque and no doubt improved throttle response and fuel consumption . The variable inlet cam would have had a say in this too . Your call but I think 8.5 is too low in an RB25 and especially when using E85 , I would be thinking more along the lines of 9.5 and if you never use ULP again maybe a tad higher . I think what would happen with a low compression 25 headed engine is a low static compression ratio dragged to an even lower effective compression ratio by its inlet manifold system . A .

From memory there are two versions of the GT Pro S compressor housing and both are port shrouded . The main difference is that one has a 100mm inlet snout and the other is 90mm with a separate machined boss fitted . If you have the 100mm version I'd say the way to go would be a reasonable section of 100mm bore hose to let the PS'd comp housing do its thing then reduce to 80mm to suit the Z32 meter . If tuning isn't a problem you could consider fitting the element and electronics into a 90mm AFM body making the difference only 10mm . 90mm is 3.543 inches and I reckon at 1mm over 3.5" you could stretch something to fit . A .

A 6 is a bit smaller and lighter than a 9 for the same engine capacity . So the story goes Ralliart developed the versions 4/5/6 and Mitsubishi Heavy Industries developed the CE etc Lancers afterwards - not the other way around . Mitsy was obviously keen to win the Group A based world rally championships which they did consecutively in 98 99 and 2000 . The 6 was the last of the true homologation specials because with the WRC or World Rally Car class cars the racers had more freedoms to alter things like suspension location points etc and the manufacturers could stick with what better suited production line processes with the 7-10 models . The updates to the 9 or MiVec 4G63T are not hard to graft into any 4 or later Evolution Lancer , mechanically its mostly in the VCT head which bolts on and takes the same manifolds pattern wise . Actually the turbo is slightly different in that the cartridge is slightly bigger and the compressor housing and diffuser section is also a bit bigger . Both can be fitted though if you really want to , I guess its not unlike putting an R33 0r 34 VCT head on an R32 RB25 block only the VCT actuator line is external on MiVec engines and the passages line up . I don't think the AYC rear diff is any great advantage and I'd rather have had the lighter less complex RS mechanical LSD , that shaves another 15 kilos off too . Just on weight the RS version of the 6 is fully 100 kilos lighter than a GSR like mine but you get no stereo aircon or fast glass , the glass in them in thinner and lighter too . The 6RS and 6TME versions got titanium aluminide turbines which are a third lighter than the usual inconel ones and some had a slightly smaller compressor too . Still cranked out the same 206 Kw on 11 pounds of boost but the torque peak was at 2750 revs rather than the GSR's 3000 . This sounds low but you have to remember that the rally classes demanded from memory 32-34mm turbo restrictors and the works cars cranked out ~ 650 Nm of torque and the drivers were changing up at under 5500 revs . The versions 7-9 made more power and torque but the peaks rose 500 revs in the road cars which is a lot in the world of production turbocharging . I'd say the 9 got MiVec because they were getting reasonably heavy and they couldn't go to 2.5L like Subaru has in the later Rexes , variable inlet cam timing would allow them to reduce the valve overlap at low revs and increase it at high revs giving more linear power delivery in a 220 Kw two litre four . I know of one slightly later Evo thats cranking out 250 at the wheels and the unopened engine is 90% std externally too . Fuel exhaust the hot side intercooler pipe and a flash tune on apple cider . They could port the head/use a better exhaust manifold/fit aftermarket cams but the things already a weapon and so much of it is factory . It drives like a std car and goes beserk from where a factory car comes on boost when flattened . I reckon the big difference engine characteristics wise between a twin scroll 4G63T and an RB26 is that the 4G will come on boost earlier and pull harder sooner . All 6s got the largest 10.5 cm twin scroll turbine housing so they don't choke on the hot side . Anyway I also forgot to mention I got my almost immaculate GSR6 with 12 months rego for 16.5K which is a lot less than the 40K for a 9 . Anyhow we all like what we like and I reckon I got good bang for buck , cheers A .

A heavy car with an engine a bit too small in std form to make it a nice street car . Nissans sollution was to fit lowish gearing and a peaky engine because the only way to make the power was at higher revs . They had an agenda , they wanted to develop a homologation special and sized the engine to fit in a desirable weight class which is fine for the stripped out race cars . Not so good when you throw in air con/fast glass/sound deadening/sound system/and 101 other things to make a road car habitable . Sorry people but you can't escape the fact that RB26's lack low down punch in a tonne and a half of GTR Skyline and the only practicle solutions are to 1)alter the state of tune to put the torque where its most usefull or 2) build in more cubes of which an RB30 short is the easiest route . These cars are not true all wheel drives because they drive their front differentials with basically a motorbike clutch - not a center differential like most AWDs do . When you have a center diff , particularly with some sort of side to side "differential limiting devise" you can limit the differentiation and make them drive the front and rear diffs all the time and when necessary at different speeds . It's not difficult to understand where Nissans engineers , back in the late 1980's , wanted to have a RWD based car with RWD handling characteristics and throw in a bit of front drive when the rear contact patches weren't quite enough . BUT they started with a car that already a bit front heavy and proceeded to fit a transfer case/front drivshafts/front differential/half shafts/live front hubs and it got a lot heavier - and forward in the car . Now weight is the enemy of performance because it pulls the power to weight ratio in the wrong direction , when you can't increase the engines capacity you have to increase the existing ones state of tune and then it loses that nice torquey drive it sedately feel . Not a problem in a race car but no one drives those on the street , they drive the porked out version with the number plates . This is the reason why I think people are talking up 707160-9/GTSS turbos , they work better than factory ones and you can still impoove other things like heads cams exhausta etc and not lose anything nice but gain it . Sure it may not allow you to have 20 pounds of boost at 8000 revs but it gives you the all important torque down where its needed most between say 3 and 6.5 . I think people need to lose the idea that a lot of boost and a lot of revs is pig heaven , it may be dramatic but its a tiresome pain in the ass to live with unless driven flat out - like race cars aim to . You see cars on the street over done , cranky cammy no guts under 4000 with atrocious driving manners and horrific fuel consumption . Not surprisingly cops love them because they're easy prey and while you may out run them you won't outrun radio waves . This probably sounds negative and not the right place to find fault with here ar SAu . The fact is that all these cars are what they are and its often impossible to iron out limitations the manufacturer built in - no matter how much money you throw at them . I know where your at , I spent for the times lots of money trying to re engineer cars and it just runs you broke . I have three cars and they are very different and span from 25 to 11 yrs old , the GTS25T is 14 yrs old and the only Nissan and 2wd/RWD . The old 86 Subie L Series RX Turbo I had converted to AWD which was a quantam leap , but it made 120 Hp std and weighted 1070 Kg . Its possibly 140 hp/1060kg now and its at a point where throwing money at it is pointless . I had big ideas for the R33 but it can spin the wheels with mild mods so why push further . I only drive on the street so what happens out 120 odd clicks is irrelevant - provided they can cruise nicely at that speed . To get the almighty rush up to 120 from rest is difficult because it forces you to try harder to make usable torque down low and get good traction at the same time . Suddenly you don't need a 4 inch exhaust or a billiard table sized intercooler , the turbo can be a similar configuration to the original one and the engine can be almost as smooth as a fresh factory one . You can afford to buy fuel AND food AND have a social life and not attract much attention from the whallopers though a lot of that depends on how you drive on the street - in anything . I don't mind GTRs but unless really really rich I wouuldn't own one , I ended up with an Evo VI GSR and its the best Jap performance I could find out of the box in its 99-2000 era . Its a lot of car and because its rock stock factory standard , ok light Enkei wheels , I know the base line and know what can be gotten out of these cars for nothing like 10-30K . This time around I don't aim to lose anything down low Mitsy built into these cars and to do this going from 206 to 240 odd at all four shouldn't be too hard . It weighs 1360 std and lost 10 of unsprung weight in just wheels . At the end of the day I reckon you should buy the car that most suits you needs in std trim because the last mods are easiest and cheapest . Your call , A .

I'd go and buy good second hand steel turbo water lines and banjo bolts from an SR20DET . They use either a Garrett bush or ball bearing center section which is externally same dimensions as your turbo . You buy new copper crush washers and bend/cut the steel lines so that they get far enough away from the turbos heat to enable the use of rubber hose to plumb to the engines water inlet and outlet . I've used EFI fuel hose in the past because its hardy re inforced so more durable than carby low pressure stuff . Unless you get them pre made and cost effectively I think braided lines for water to 110C and 14-16 pounds pressure is over kill and more expensive than it needs to be . A .

Space made Mt Woolaf , still struggling with this revised format and not liking .

You would probably be better off looking into turbo diesel engines of your capacity and seeing what turbos they use as standard . This would give you a base line into sizing which is a good start . Be vary carefull not to go too big on diesel turbos because you have a limited rev range to start with , also diesels mostly lower combustion temps means you can run a fair bit of boost without melting anything . You get a bit of a free ride with detonation ignition too ! Also make sure the intercooling is adequate because diesels like good charge cooling as well . A .

Save your money and buy an R32 GTST and RB25 or 30DET that . If you can live with a four banger buy a Silvia . No offense but a GTR is a poor choice for a drifter and far cheaper cars would do the job a lot better IMO . GTRS are heavy cars and throwing more money/cubes/power at them doesn't fix this . A .

The ignitor is just a high speed switch only in this case they are built into the coil assembly . Some will say that returning to high tension leads is a backwards step in this day and age . I reckon by the time you muck around with brackets leads wiring etc you may not have a lot to gain and it creates a bit of an eyesore . Can you source good second hand std coils or explore ones off other RB twin cam engines ? A . I know OT but so much more to be gained from a 25 if you can manage it .