discopotato03

Yes the HKS GT3037 Pro S turbos use the same cartridge as Garretts GT3076R turbo . The cartridge number is 700177-5007 so you can shop around for the best price on one of them . Anyone who can remove the compressor jamb nut and the oil inlet ferrule (without bending anything) should be able to strip the cartridge and assess it for you . The advantage of a ball bearing center section is that aside from the turbine end piston ring type exhaust gas seal nothing actually rubs against the bearing housing so unless its had some mechanical failing or the wheels are damaged it may be reusable . It really depends on what the turbo shop has in the way of spare parts . A .

Laggy turbo for RB2570cc engine . AFAIK the KAI's have the 94mm OD compressor where the SPL's have the 102mm one . Just a little background info on the Garret T51 based turbos . The name T51 comes from the older tech T series turbine they use in 76 trim . Garrett use the "R" prefix to differentiate ball bearing from plain bearing units . These units use the large frame GT type center bearing housing but as in with the T04Z from memory they machine the turbine housing mounting ears of the back of the bearing housing so that they use the older T series crab plate style fastening system . Garrett's GT4294/R and GT4202R/R cartridges are very similar except they use a more modern GT42 turbine which is unfortunately in 84 trim . I seem to remember the HKS T51 versions having at times slightly smaller compressor wheel trims but I don't remember the details , not interesting to me personally . For an RB26 that's often street driven if you want a more practical HKS turbo then have a look at their T04Z , still not exactly small but at least you'd get same day turbo response . A .

What does an R32 GTST weight with the R33s engine gearbox and brakes ? Just curious , cheers A .

I just wanted the most direct path to the end result , if you like doing engine and gearbox changes plus the wiring etc for kicks go for it . Then the diff ratios wrong and the brakes are getting so so etc etc . Often when you go to sell a car the age of the thing has a say in the zeros , the R32s are getting long in the tooth now and everything original has to be getting a bit tired . R33s had lots of updates over the R32s and while they are a bit larger and heavier the bigger engine and beefier drive train makes up for that IMO . To each their own , A .

Like in the other thread , sell the 32 and buy an R33 RB25DET with a GTS25T Skyline bolted to it . Get all the bits that are designed to support an RB25DET as it is from the factory . Far easier to buy it than recreate it . A .

I once thought about the larger engine in an R32 GTST scenario and ended up with what I reckon is the simpler solution . Nissan put an RB25DET and the big box and larger brakes etc etc into the GTS25T's and I reckon its far cheaper and easier to buy one than create one . There's nothing stopping you buying an R33 and selling the R32 , update to a later car with more resale value and more of what you want out of the box . The effort to rip half the drive train out of an R32 and trying to get something back for the donk and box is considerable . The R33 with reasonably straightforward bolt ons/plug ins gets you where you want to be . A .

Your call but I think you'll find the VG30 turbos turbine housing a bit big for an RB20 , don't forget that a 3L is half as big again as a 2L and they make considerably more torque off boost as well . I'm not sure if you are aware but the BB VG30 turbo actually uses a slightly smaller compressor wheel than the RB25 ones do - at least the R33 RB25 ones . If you try to fit the compressor housing off the VG turbo on an R33 RB25 turbo it won't go over the compressor wheel . For a straight bolt on the R33 RB25 turbos are probably the go . They don't look it but the RB25's turbine housing passage is slightly larger than the RB20's one so I think a good try . The OP6/VG30 turbine housing is a reasonable amount larger than the RB25's one , more than the difference between the 20 and 25 . A .

I'll offer my parting thoughts and call it a day . I see people say I get full boost at so and so revs and its like they think they have to be at the regulated pressure setting to go well . I reckon the important things in a road car are do I get reasonable part throttle boost/torque and will the engine pull when I want it to . I believe if you have to have the throttles fully open to have any worthwhile squirt then the state of tune is too high for the street . IMO the aim is to have useful torque using the turbos to shove a useful amount of air into the engine to achieve it . From a challenge point of view its a shame I'll never have a GTR because it would have been interesting trying to get a more Evo like power curve into say an R32 . I know enough from having a 25T that Skylines have a bit of a front heavy feel about them and from drivers who drive them that GTRs feel it even more so . I doubt I could get one to feel and drive nicely for me without it being striped out like a racer and who wants to drive a tool shed around . Most of you would think I was mad but I'd have tried the R34 BB turbos and done head work and shortish high lift cams . Higher static CR and spent time getting the tuning right . -9/GTSS turbos would be the largest I'd have put on a full weight std capacity GTR because even they are more than good enough for street performance IMO . Anyway subjective because I don't aim to have one . Cheers A .

To get the most from OE housings you need the OP6 turbine side one from some R34s and the single BB Z32 VG30 four cam engine . It will help reduce the turbine inlet pressure so you make more power per pound of boost and reduce the force/area on the face of the wastegates flat valve . I know people who cranked about 266 RWKW out of an RB25 with head work/cams/GTR IC/larger injectors and a PFC . I think the boost was around 16-17 pounds . A .

From a competition perspective brutal mid range torque is what rally engines are based on , they don't rev because they have turbo restrictors which put a limit on how much air can be drawn in with only atmospheric pressure outside them - at best . sthe Sierra Cosworth and they failed dismally because the gap between lag and restrictors the flow limit was initially very small . All the manufacturers/teams had to reduce turbo size so as to get them to make boost and have a wide enough usable rev range . Anti lag systems were also used but they are very hard on the manifolds and turbos because of very high exhaust temps through them . The R33 GTS25T thing is very different to the Evos and equivalent WRX STis . From memory the 33 makes 184 Kw and I'm not sure where the std cars torque peak is . The figures for my Evo 6 GSR is 206 Kw and the torque peak is at 3500 revs . The STi GC8 was I think a little lower Kw wise and they were noticeably lazy up to about 4000 revs . Both the AWDs are lighter than an R33 in the case of the Evo 6 had larger wider wheels and tyres . My GSR std weighs 1360 Kg and the stripper RS 1260 Kg . They have 20 more Kw , weight 120 kilos less and have AWD and more rubber to put the power down than a GTS25T . In fact my R33 and the Lancer both have 17 x 8.5 wheels and 235/45 tyres on them and you can guess which digs it claws in best under all conditions . I'll agree that Nissan wasn't after extreme performance from the GTS25T's , they obviously had the GTRs to carry the flag in that era . Also from what I read it seems that people don't modify RB25's to make strong low to mid range torque , most want the 240+ RWKW and there will be a rev penalty paid for using single scroll turbos large enough to handle the gas flow for 240-300 Kw . It is possible that making lots of low to mid range torque in a 1380 Kg RWD car would make for lots of wheelspin so when it comes higher up it happens at higher speeds where traction could be less of a problem . A good friend keeps telling me that the Prince Motor Company was where the Skyline brand came from and they always intended them to be an open road GT type car . The Evos and STi Rexes are a bit harder edged and bite harder in the on/off throttle operation than the RWD Skyline , they are more sure footed and chuckable IMO and my Evo anyway is much sharper in its response to driver inputs . Just different factory developed DNA for different purposes . A .

Volumetric efficiency and dynamic compression ratio are directly related meaning if an engine can breathe well enough to completely fill its cylinders the dynamic CR will be close to the measured CR . The other side of volumetric efficiency is the hot side or how well and completely the cylinders blow down whilst the exhaust valves are open . There is a basic problem with exhaust driven air pumps and that is attempting to keep the exhaust and inlet manifold pressures as close together as possible . When you can achieve it you get the ideal pressure balance across the head meaning it has the best chance of scavenging or blowing out the residual spent gasses and heat at the end of the exhaust cycle . The basic single scroll turbo system can do it with very large AR ratio turbine housings but don't expect the thing to start pumping air too early . Also there are two big advantages twin scroll systems have over the single one . Firstly the engine has less resistance to venting its cylinders and scavenging properly AND the pressure rise across each scroll is greater purely because it was lower to start with . The rise in velocity of the exhaust gas is greatest just as the exhaust valves crack open and its this sudden bust of hot gas that gets the turbine accelerating sooner or lower in the engines rev range . In the diesel world TS turbocharging was designed to help the engine make strong torque at lower engine revs without losing anything further up a diesels generally short/narrow rev range . It can at times be a way of getting larger capacity engines low down torque without the capacity increase . Larger cylinders are usually hard to beat but getting all 43 beans out of any engine is better than only getting 35 out of a slightly larger one . Capacity increases . Most production engines these days don't have real thick cylinder walls mainly because more material costs more money and adds avoidable weight to increasingly heavier cars . The blocks bore centers can be closer together meaning a shorter more compact engine , manufacturers like Toyota/Nissan/Mitsubishi have four cylinder lumps used in transverse as well as inline apps . Examples are Toyotas 4AGE , Nissans SR20/Mitsys $g family . Short engines are easier thrown in sideways between the towers of FrWD and some AWD cars . I pity people who drive east west FrWD V6 cars ... Anyway you can increase the capacity of these fours by increasing the cranks stroke and it doesn't work out too badly if say the blocks height is raised so that the con rod length is increased - better rod/stroke ratio . Some would argue that stroking is a bad idea but remember that these are production engines not race ones and Joe average isn't going to rev it past 4000 most of the time . Example engines are Nissans RB30 , Toyotas 7A , Mitsys 4G64 . Nissans stroke is still less than the bore size but then again the smallest "big bore" RB engine (RB25) is very much a short stroke engine for its bore size . No one in their right mind would increase stroke length and decrease bore size for a given production engine to argue that stroking is a bad idea . The increased cylinder capacity will always result in more air and fuel to compress and burn and provided the engine is not revved past its safe mechanical limits it should make more torque than a std stroke version . There's a lot more to it than that because the manufacturer designs an engines breathing characteristics to promote torque in a given engine speed range and when the cylinders are larger the gas gas speed through everything is greater for the same revs . Also the gearing is designed to match what the manufacturer wanted from their std product and its state of tune . So IMO things like an RB30DET in an R33 should have a taller diff ratio , thats what I think Nnissan would have done had they made such a car . Other places to be , cheers A .

Hmm , good thread this one and I have a Subie an R33 and an Evo 6 . The real answer is that there isn't one because there are so many variables . The most significant one is that its impossible to directly compare a four and a six cylinder , even of the same capacity , because the firing orders are different and so is the number of crank degrees per power stroke . The given example was a 2L four and a 2L six , the fours power strokes in theory create more shove but the sixes ones are closer together ie 120 degrees for the six and 180 degrees for the four . I disagree about the square or same bore and stroke , the best four I ever tried was Nissans old FJ20 and they were 89mm bore + 80mm stroke . From memory the rod centres length is 140mm . They make great torque and rev like a turbine if the exhaust system isn't restrictive . The point you have to remember is that the piston crown area is that which combustion pressure acts upon and the large bore size is that which allows you to have a lot of valve area before they hit to sides of the bores . Anyone who tried to hot up an RB20 soon worked out that you can't really increase the valve sizes because they clout the block . Something interesting four pot wise was what Nissan did to the "SR20's" when they used them in the 2L Super Tourer class . The rules allowed them to do really extreme things with the blocks and heads and what they ended up with was roughly the FJ20 bore and stroke and possibly more weld material than head casting . I thing the engine ran in the opposite direction and they turned the head around on the block drove the cams from the opposite to OE end of the head . Turbo rally engines are very different to tarmac race in that they have to make killer torque from low revs and are strangled by turbo restrictors so swap cogs no kidding at 5-5500 revs . The 4G63Ts are not a square engine and like many production transverse engines need to be short to fit with a transmission across the engine bay . They make good torque because of the rally homologation development and are in a reasonably high state of tune for a production engine . Things like the CR being around 8.75 - 8.8 helps make them crisp and make more low end torque than say an SR20 at 8.5:1 . The largish intercooler in the nose of an Evolution Lancer means you can have the higher CR and higher than average boost pressure without the rattle rattle dramas . They don't get short changed with radiators and many have a proper air to air oil cooler as well . People like Corky always said that thermal issues are the achilles heel of forced induced engines so if you can beet the extra heat they generate they become a lot more reliable and effective particularly in higher states of tune . The Turbochargers . Subaru initially used IHI turbos on their EJ engines eg the VF12 on the AMD Liberty RS Turbos . When Rex turned up it got a Mitsubishi Heavy Industries (MHI) TD05 dryer and in the later 90s a TD04 because everyone bitched about turbo lag . What they could have used as a better compromise was the large turbine version of the TD04 ie TD04H instead of TD04L , actually the rare auto wagon JDM early WRX did get this one std . My opinion is that Fuji botched the 90s era EJ20 turbo engines exhaust header wise , a real dogs breakfast except for the later factory twin scroll header manifold and turbo system - TS turbine housings . BTW they had both IHI and Mitsy TS turbos too , search TD04HLA-19T ... EJ20 turbo engines with the stone age header system (single scroll system) get real laggy real quickly with larger turbos . Its partly because flat fours have a screwy firing order to stop the engine lunging from side to side with each power stroke . They fire the cylinders in each bank then swap to the other side and do the same again . Looking from the front ist left front left rear then right front right rear , the firing order is 1324 rather than an inline fours 1342 . So you say ? Problem is that you get two exhaust events from each side close together the a longer pause before reverting to the other side . Just to screw things up the nearside head has a long engine pipe around the front of the sump and the turbo side one is real short before both joint and feed the turbo via the up pipe . The result is unevenly spaced exhaust pulses and scavenging , its also the reason you get that silly boxer burble when you use a storm water drain for an exhaust pipe . The twin scroll EJ20's sound more like an inline four and are more of a basic fix than an upgrade . Just on boxer con rods , yes the big ends are big and narrow because flat engine cranks are quite short so the rods/webs etc need to be wide and skinny . And yes the split aluminium engine cases can have rigidity problems at times . Mitsubishi got wise in the Evo 4 era and decided to go with a twin scroll turbo system and it works really well . Size for size the Mitsy turbos tend to work better in Evo guise than Rex guise mainly because of the twin scroll turbine housing . Those Evo 4 TS turbine housings were small (for a TS) at 9cm but Mitsy soon worked out that the larger 10.5cm ones worked even better ie virtually no more lag and less exhaust restriction . Your typical Rex single scroll housing is usually in the 6-8cm size range and the larger ones can be a bit lazy . Now to the RB6's . These are very much late 80's thinking (RB20/26) with the 25 being a less costly destroked version . The R33 brought variable cam timing and the R34 got non hydraulic buckets and a bit more VCT sophistication . Some like SK think that the valve size ratio is wrong and that the exhaust ones could have been a bit larger . I don't think I'd do an RB30 without doing both because any breathing restriction means less complete cylinder filling esp off boost and it cost you torque - and power up high . It would be interesting to know what Toyota does valve size wise with 2JZ GTEs . Good grunty low to mid range performance in production cars comes from making good part throttle torque without a lot of revs . A critical part also is gearing because if its not well chosen to make use of this part throttle torque then its largely wasted . With turbo engines the secret is having a high 8's CR and a head/s that breath really well . VCT is a way to have healthy cams and opening them up to have less overlap and high trapping efficiency at low to medium revs . Good intercooling is a must because higher CRs + healthy boost means heat and if not dealt with detonation . Multiple throttles are a nice if expensive option because they offer the least throttling restriction and while shut reduce the reversion effects of healthy cams . All Wheel Drive - the permanent variety . No real substitute for having 100% of the weight of a car on its driving wheels . Double the contact patch area of FrWD or RWD's and they share the drive loads . Two of my cars are permanent AWD and that puts an end to the spin tramp my R33 gets if I boot it off the line in the dry or over every painted line on the road in the wet . The torque you can put to the deck with them kills the R33 off the line and they don't feel taily at all . Power delivery wise the single turbo RB25 is crying out for a twin scroll turbo because it can't scavenge or breath out as well with the SS turbo or get the turbo spinning up as easily either . It may be a legacy of the fact that RB thinking came out of the 80's when twin scroll twin integral gate turbos virtually didn't exist . The 4G's are a reasonably well designed 4 cylinder twin cam engine but there no F1 engine . The overall package functions well and everything is designed to work together . They went through many revisions close together because Mitsy wanted to stay competitive in Group A Rallying and competition R & D soon shows what works and what doesn't . I don't think Nissan went to anything like as much trouble with the RB family and even the 26's had a short life in the competition world . Nissan could have done the same things that Mitsubishi did but I'm told they were in financial hot water and the RBs and SRs weren't going to get beyond the 90s anyway . Just for the cc list Porsche had a 3L four cylinder for a while , the largest petrol four I know of . Paul go for a ride in a mildly modded Evo 6-9 and see what you think , more like a toned down go cart than a four door sedan but its that too BTW . No fingers left , cheers A .

Most people find the BB VG30 turbo laggy on RB20's mainly because its turbine housing is intended for an engine half as big again and its not like your going to rev an RB20 50% higher . Also note that Nissan used that larger Hitachi turbine housing on RB25 Neo's but they had a more sophisticated variable cam drive system (than R33s) to help keep the dynamic compression ratio up at low revs . As far as I know RB20s didn't get VCT so using a large turbine housing is going to make the turbo pretty lazy on them . As I mentioned elsewhere I think a re-machined Hitach RB25's turbine housing , which is a little larger internally than the RB20s one would give a bit more flow area and allow you to make a bit more power without excessive turbo lag . BTW I KNOW the 25 housing is a little larger than a 20's one because I have all three sizes here and measured them internally . They don't look a whole lot different but they are and I know it to be fact . RB25 turbo bits are common and cheap so I'd use an RB25 housing as a first try . Its the next size up from what you have and has the best chance of not being a laggy pig on a two liter six cylinder . Your call , cheers A .

If you are sure the gasket is leaking you should pull the head off and make any determinations based on what you find . Its pointless guessing what has happened when you can't see anything . People I know are not big fans of Cometic head gaskets and for normal use they often use a genuine gasket or if the manufacturer has a competition gasket gasket available one of those . Always remember that an inline six the block and head are long so the surfaces must be flat and square or things will leak . If the engines doing super duty studs and nuts are always the best fastening option . From what I hear RB engines don't have HG issues std but if you screw a lot of boost into them then its the same as any half decent OE engine . I believe the wire rings work because they sit in a groove in either the had or the block and attempt to form a mechanical lock just outside the headgaskets fire rings to help prevent them moving and breaking their seal . I know many won't agree but I think copper gaskets were a means of having a cheap reusable item which could better stand up to high cylinder pressures than the cereal box gaskets cars had back in the 1970's . Their problem as I see it is that its asking a lot for a non ferrous material that sees uneven heating to remain a uniform thickness after lots of heating cycles and being annealed to go again . Also its not at all uncommon to see them leak water or oil via small machining marks on the head or block . Your call , for road I think an OE gasket with stainless rings are fine if done properly . The next stage is to cut the fire rings from a good new conventional gasket , machine same depth steps in the tops of the bores and use parallel wall rings to physically lock the block to the heads deck face . The conventional gasket minus fire rings seals water and oil like they are designed to . The crush seal is critical and the compressed thickness of the rings and gasket has to be carefully worked out . I think Alex at Plazmaman was the first person I'd seen do this on his 700+ Hp FJ20's . Thats three and a half times the factory FJ20 output BTW . Your call .

I think you'll find that the two ports on the turbo side flange are sized for the twin inlet T3 flanged turbine housings - if they are std . Actually what people call twin scroll T3 flange I believe is actually named "Euro T4" even though it has the same bolt pattern as single entry T3 turbine housings . The Big T4 flange size has much larger ports than the T3/Euro T4 , some call the big T4 size T4 International pattern . If you ever get to see the RB26 version of the HKS single cast low mount manifold you instantly notice how big its two outlet ports are . It because it was designed to have a HKS spec TA45S turbo on it and they use the T4 International flange and port size . I'm not even sure you could port the RB20 HKS manifold out far enough to match the twin ports in the larger T4 International size footprint . As for those twin scroll turbine housings from ATP , have a look inside them if possible because some people reckon they're a bit dodgy looking . I've no idea who makes them and no ones said they have Garrett markings on them so anyone's guess . A .

As far as I know no one is doing a "T3" flanged twin scroll twin integral gate turbo so far . I doubt this situation will last forever since Mitsy has done so well with turbos like this , except in their own flange pattern . Actually HKS is now doing a bolt on BB TS TIG turbo for the Evos 4-9 and its supposed to be a nice if expensive unit . It looks to me like Garrett is being left behind with wheel designs and trims and it remains to be seen if they'll do anything about it . Slightly larger wheels and or smaller trims is working better for the other turbocharger manufacturers and when you throw in TS turbine housings and port shrouded compressor housings they can be wider ranging things . A .

It not really as simple as that because not all turbine and housing families are created equally . They are in any case a two piece combination meaning the turbine and the turbine housing , neither does anything useful without the other . The Area Radius ratio relates to the volume of the passage leading to the housings nozzle section . It makes the grand assumption that no ones bored the housing out for a larger diameter turbine as well . If the question you are asking is can the mass flow rates be compared then the answer is yes . If you are asking is there a direct numerical conversion ratio wise from T3 to T4 then I would say no . The reason being that the turbine wheel has a lot of say about how the combination flows and there can be a big variation in what people call "T3" turbines and a few different T4 ones . You have to understand that what say I call a T3 turbine is the heavy inefficient little horror fitted to Z18's FJ20's RB30's etc . There is a range of TA31/TB31 turbines that many call T3/Sierra dash 1/2/3 . Not really T3 but jammed into old T3 housings not really suited to them . The Buick Grand National stuff was called "T3" But I think they come under the TB41 family . Also confusion exists because you can have internally T3 dimensioned housings with T4 mounting flanges on them and T4 housings with a T3 like flange on them . I kid you not some diesel tractors have 1.06 A/R twin scroll T4 International mount flanges on them but with quite small gas inlet ports . Inside lives a dinky little early 70's tech T3 turbine . What exactly are you looking at ? A .

What do you think it would cost to make up a spacer plate , fit it to the block and bore the "sandwich" for thin walled liners ? Paint the block keep your number and claim the 5th if questioned . In with the 30 crank/rods/pistons and have a real torquey "RB25DET" . Don't they all roll off the boat looking like that ? A .

Well in some ways I relate 26's in GTRs to RB20's in R32 GTSTs , turbo choice can improve the factory product or push the top end higher . I suppose having an RB25 in a RWD R32 does similar sorts of things to having an RB30 in a GTR as far as low down torque is concerned . To each their own , its just than it can be frustrating to see people built exactly what they won't like and have to suffer it because they can't afford to do the job again . I still have my 25T but went to an Evolution Lancer because on paper it has 3 Kw less and is 120 kilos lighter than a 32 GTR and my GSR6 is the heavy version . Approximately the same size brakes/wheels/tyres as a V Spec R32 and on paper makes its peak torque at from memory 3500 revs . They are far easier to get user friendly gains out of than a GTR while still being acceptable as a road car . If GTRs are your thing then go for it , just remember that they cost a lot of time and money and if you're trying to change the factory dynamic of what they are you may be painting yourself into a hellishly expensive courner . Last time , they were the basis of a narrow focus Group A tarmac racer where low end power was of no consequence . This shows in the road going cars as well . The Evos up to 6 were also factory homologation specials but the power delivery and handling attributes needed for rallying are very different to tarmac racing . They have to be light/nimble/agile and punchy to have any hope of being competitive . In my opinion what works for rally is MUCH closer to what works in a toned down road car because it isn't the constant high speed abilities of a tarmac racer that is usable on public roads . I'll be honest , Godzilla and Nissan did great things to the automotive world in the early 90s but the death of turbos were always going to kill it . I get my fix from dusting off my 92 Bathurst video and watching it . Hair dryers and AWD lived on in International Rally classes and the rule makers forced the manufacturers to develop engines that made strong mid range torque (650 Nm) from 2L with turbo restrictors . In registerable form the same dynamic works and I guess that's why Mitsy and Subaru have sold so many AWD turbo cars , far more that Nissan ever did . A .

Yes as Tom said torque is a measure of turning force and it can be a load measured at zero speed . The thing is that once that turning force overcomes all forms of resistance its what creates rotation . The points I've been trying to make are where in a given engines usable rev range adequate torque exists to drive you down the road adequately and have more potential torque just a light throttle squeeze away . I think I can truthfully say that chasing higher than normal revs to have the above mentioned situation is nothing to boast about . Tom is quite right in what he said about torque and gear ratios/wheel diameters , an engines torque peak is where maximum torque output occurs but if the wrong ratios are not used/fitted the torque Multiplication won't be ideal . Another point I'll spell out involves turbo performance (response) vs engine speed and torque delivery . A well thought out and sized ball bearing turbo idles or windmills at reasonably high speeds even when engine load is not high or throttle fully open . There obviously is a point below which even wide open throttle (WOT) won't produce a lot of torque or acceleration - the engine can't because it isn't venting enough exhaust heat/velocity energy to spin the turbine/compressor rotating groups fast enough to do much . The BIG question is are people going to be practically minded enough to chose turbos that will produce some part throttle extra air and engine torque (Plan A) or are they biasing their engine spec on what happens at WOT and 4-8000 revs (Plan B) . In my opinion there are turbochargers for RB26/GTR that try to achieve Plan A and I personally won't bother deciphering why people opt to do much else on an almost totally street driven car . These 707160-9 turbos have most of the smarts to be better everywhere than any of the OE RB26 turbos - except maybe the R34 GT2556Rs right down low . The nice light NS111ish turbine in the smaller 62T trim size , the low friction BB center section , the obviously dialled in 56T 59.6mm compressor wheels . Blind Freddy can see that Garrett didn't put large housings on these turbos like they do at times with single GT25/GT28 BB turbos but then again they aren't often going on the side of effectively an inline three cylinder like parallel twins on an RB26 do . Actually that's not strictly true because an inline three's continuous cycles don't have the extended pause between exhaust events like an I6 divided in half between 3 and 4 does . Engines that make extra part throttle torque from forced induction are always nicer to drive because they tend to feel linear and more like a larger that std capacity NA engine . You can't escape the fact that this is because the engine torque is increasing earlier in the engines rev range than either no forced induction or turbos sized too large to achieve this . The bottom line is that a 2568cc 8.5:1 CR engine is not going to be impressive with just atmospheric pressure to charge its cylinders (minus any inlet system losses that is) trying to drag around an almost 1500 kilogram Skyline . Without the dryers they would be a total slug , when the dryers don't do anything for whatever reason including sizing it's the same deal . Just on Toms long vs short stroke myth theory . Fact 1) How often would anyone increase the stroke and reduce the bore size ? Not too often I'd think . This gets bandied around a lot but I think essentially the question being asked is will my engine make more torque low down if I increase the cranks stroke . My thoughts are that provided the rods don't get ridiculously short yes it should make more torque down low because the cylinders capacity has increased - in theory more air and fuel to compress and then burn . You'd have to say that increasing the stroke of an engine that the factory had already done this to might be doubtful but if you cant increase the bore size and revs are kept low it may be the only way . I don't look at an RB30 as a long stroke engine , I do look at an RB26 as being long in the stroke for the deck height of the block which means shortish rods etc . AFAIK the RB20 was the original and smallest of the RB engine family and they pinched their bore/stroke dimensions from the old L series L20a . In some ways I wish Nissan had used a taller deck height on RB25s and RB26's but they obviously wanted to stay within the external dimensions of the RB20's block . Plainly it was never going to work with a 3 litre engine and the bore centers are not wide enough in the RB family to increase it significantly . My thoughts are still the same , turbos sized to drag torque out of a 26 lower than Nissan had it or throw an RB30 at it . It's still possible to drive enthusiastically a car that's makes good torque without too many revs , lots of haul without necessarily warp 9 velocity . Get in a car that's a Honda Zot up to 3500-4000 and see how fast you're going when you get to the meaty part of the rev range in 1st and 2nd gears . In the excitement wave to the cop or contractor in the plain white Territory with the dinky little radar dish on the roof . Six cars a second they are claiming they can nail at any one time . Race spec cars are useless to me on the street . A .

Nee-san that's THE exact point and while its trivial to some its everything to many like I think you and I . Its the lack of part throttle squirt and the need to go many places at wider or full throttle that makes cars at times irksome to drive . My personal opinion , and that's all it is , is that people worry far too much about what happens north of 6000 revs . I really do wish people could datalog how they drive their cars so they could see absolutely how much time they spend up there . I just can't get my head around tuning an engine to make power up there - and seldom use it . People buy V8 powered cars because they make easy lazy impressive torque without having to buzz the engine - keep the revs up so when they prod it it shifts its arse smartly . I don't see a car as being tough because its lazy to get going , it moves away from a car being a relaxing easy thing to drive . To me sporting/sporty cars have to have some low to mid range - or they don't FEEL sporty . To me having a hyped up homologation special is not justification for constantly hold the revs up . To be brutally honest cars that make real torque at sensible revs feel fast because acceleration from low/no speed is what gives the impression of power/speed , it requires strong torque to achieve and there is no substitute for it IMO . Some cars that really are fast don't feel like it , some that won't ever crack 200 feel like they can tear your seat out of the floor . I'm different , I like different things . My god is massive torque and traction that can harness it . I don't need a long extended rev range and strong torque as the engine reaches death is imminent revs , can't see the point . When the thing starts to run out of breath pull another gear - that's what they're there for . Actually if the manufacturer was nice enough to give you a closish ratio gearbox you don't need to pull telephone number revs before changing . Stay closer to the engines torque peak - and have good acceleration . I think that was the intention with the R34 GTRs having taller final drives and six closer spaced gear ratios . They don't have big turbos and people don't think they are slow . I'll never have a GTR because of the expense and complexity of the things . But if I did I'd be doing my level best to drag every foot pound out of the thing under 3500 revs that I could because that's what feels good in the real world . I'd be thinking about the RB30 before anything else because even if the turbo/s fell off it would still have something to get going with . Sorry people , GTR was homologated with an engine designed to suit a race car class weight and torque down low is irrelevant in a Grp A tarmac racer . Nissan at the time was is dire financial straits and didn't bother to resolve this situation in the R33s R34s which were not homologation specials . An RB30 and VCT would have solved these problems but for whatever reasons Nissan kept the same basic drive line - and didn't race it . You have the opportunity with non std turbos on a GTR to make them better than the factory had them everywhere - torque wise . You can enhance the second half of the engines rev range with little though to the first half like Nissan did , or you can pull it up earlier with more mid range and top end than std which is what makes a nice road car . No one drives a road car flat out everywhere and its hard to argue driving flat footed always is good . There's nothing to stop you doing all the manifold/head/cam upgrades to an RB26 with sensible turbochargers , I think it was WilliamsF1 here years ago that made his GTR really grunty with GTSSs doing just this . I'll be blunt , make torque and have it usable and accessible . Numbers people I suppose have to have power at revs to achieve a number for its own sake . When you get sick and tired of chasing the moon torque becomes everything . How much how soon and does the spread of torque match the gearboxes ratio spread . Do what you will but don't come back and say I wish my car had some bottom end because you have/had the opportunity to do something about it . A .

Nismoid 90 odd DB is very quiet for the tube size . I don't suppose you could let on what type of mufflers they use ? Cheers A . If they can do the impossible its worth the money and lack of grief .

I am talking about torque at around town revs , for the state of tune of a std RB26 it isn't sprightly enough in an almost tonne and a half car to feel nice . The original design concept was an RB30 , 2568cc was all about running in a weight class for tarmac motor sport . A .

Well your call but for the effort to R&R turbos on an RB26 I'd be using ball bearing bolt on ones . The reasons being that they are more reliable and longer lasting - often the wheels in them are later aero tech too . Don't forget with R32 GTRs Nissan was doing their R&D back in about 1988 and a LOT of water has been under the bridge turbo wise since then . Yes the old N1's were really laggy and only seemed to work with the boost screwed right up . Then when the old bush/plate thrust bearings lunch themselves , all that work and money to spend again . Really I think the OE R34 BB turbos should be seen as a practical base line . You time money patience , cheers A .

I think people need to have a base line and have a look at what these cars/engines did out of the box . I'll assume a standard S2 GTS25T makes 185Kw which equates to 247 Hp or 99 Hp per liter . If you want 500 Hp from that engine the numbers crunch to 200 Hp/L so 100% increase . Given the opportunity generally cubic inches make the easiest horses so factor 3 liters into the equation , 500 divide 3 equals 167 Hp/L . They make more torque because they are a larger air pump , ~ 20% larger . They'll spool a larger more capable turbocharger earlier than an RB25 whilst making more torque down low . You would be asking a lot from a real GT3076R to pump 50+ pounds of airflow and using the largest available housings would be the way to do it efficiently . On an RB30 a GT3582R would do it easily if everything was done right . Think hard for a sec what Mr Mafia said about his torque number - 720 Nm from 3000 to maximum revs . I wonder how many RB25's wearing big turbos can do the same or better from 3000 . Take it to the grave , TORQUE is everything while Hp/Kw is a fancy Mores law way of impressing Joe average with a healthy looking number . If manufacturers were being truly helpful they would rate their engines on torque numbers rather than a torque number multiplied by engine revs . Turbo diesels are a good example to look at , advertised as making SFA Kw's but the torque numbers can be fantastic - compared to a same capacity petrol engine . The other thing is that tractive effort is critical when you start getting good torque numbers , all the torque in the world is useless if it goes to the dogs with wheel spin . A lot of money gets spent making power that will likely never be useful without very capable tyres/suspension on a real good surface in dry weather . And even then I'd reckon its going to be tail happy driven hard . Can reduce the timing 8 degrees (sounds like across the board) , and the torque peak doesn't change ? Something really wrong with the tuning method there . I really had hoped we'd grown beyond the stage of reducing static CRs by using thicker head gaskets - particularly in an engine that's been opened up and better pistons fitted . THIS IS DARK AGES GARBAGE ! The dinosaur theory was that increasing the volume above the cylinders swept volume reduced the CR which lowered the cylinder pressure/temperature before the forced induction artificially boosted it . Trouble is that the further the piston crowns are from the heads quench pads the worse the chamber shape becomes and this often LOWERS an engines detonation threshold purely because the quench areas don't work as well . Pent roof combustion chambers and four valves per cylinder were designed to give you a lot of valve (breathing) area in a compact combustion chamber and part of keeping the chamber area small was having those flat "D" shaped sections beyond each pair of valves . Jacking the head up on a thicker gasket increases the large flat washer area above the flat outer area of the piston crowns so it can now have a greater volume for end gasses to hide in and auto ignite before the spark initiated flame front reaches them . Result - rattle rattle bang bang $$$$$$$$$$$$$$$$$$$$$$$$$$$ . The correct method is to have the right volume in the pistons dish to set the static CR which then leaves minimul volume between the piston crowns and the head face , smaller volume of end gasses , air and fuel , less to detonate . For its day the old Cosworth BDA (Belt Drive A Series) had very good chambers but the narrow valve angles are hard to make in a head that's not very tall - like most twin cam production heads are for engine bay packaging reasons . Another epic I know . Bottom line is that traction is the limiting factor and torque beyond tractive effort is pointless . The other one is that torque wins races and horsepower sells cars , its as relevant today as is was a lifetime ago because the physics haven't changed . AWD is the only practical way to have high tractive effort in an un tubbed car . Sad but true . The good news is that E85 at the bowser is coming so hopefully there will be a cheaper way around octane limited ULP and we will be able to make good torque with less extreme states of engine tune . A .