discopotato03

Fantasy I can't remember what grade stainless they use , Geoff did say that its what gets used in Nuclear power station cooling systems so I guess it must be pretty good stuff . From a wastegate size point of view the situation is very different to a single scroll turbo system , the pressure variation is greater with the average being lower . Lower pressure means greater valve area to move the gas . Twin gates are obviously going to cost more but its the only way to totally isolate the parallel systems . I can see where the paying customer is going to question the value in using two , IMO this falls in the grey area where the result is paramount and if the competition is stiff it may just win the day . Its very hard to justify the budget and effort to use this kind of gear in a car with number plates . The more I think about it the better parallel twins look in a registered car , far more legal looking and can use more of the factory supplied bits . I reckon I'd inquire about extrude honed factory manifolds , GMS had good times with some variation of them and the early Grp A cars were good for around 650 brake horse ? Nismoid , I have seen std and aftermarket RB26 turbos but never had much interest in them because there not much use in a single turbo app . When you mean their turbine housings do you mean the std factory ones (0.48 ?) or the HKS 0.63 2530 type housings ? Cheers A .

I'd expect a properly developed manifold in the same grade of thick walled stainless to cost similar money out here . A lot of manifolds I see here are an exercise in making 6 holes into 2 or 1 . To develop something with 6 runners , equal pressure drop and a collector that works is no small ask . If you ask Geoff what sort of effort goes into developing and producing their manifolds I'm sure he would be only too happy to explain why . Its only an E mail away . Cheers A .

Jippa3000 fair enough . Well if it was me I'd get the head off and get it serviced and some porting done . I'd look at doing a valve train that can handle more valve lift with a bit more but not extreme duration . What this does is make for better cylinder charging and venting because the greatest obstruction in the ports is the valve heads themselves . The idea of short/med timing with extra lift is that the valves are open further per cam degree because of the more agressive opening ramps on the cam lobes . If you don't go over the top on duration it shouldn't run like a hairy goat , The trapping efficiency of sane duration cams is quite reasonable and the better breathing from the extra litf shows up as more torque from a bit higher volumetric efficiency - provided other restrictions don't gang up on it . RB's seem to like a little larger exhaust valves too . I'd also talk to Geoff Raicer from FullRace Motorsport in the US who amongst other things does really nice fabricated RB26 twin scroll exhaust manifolds . He's been there with a few various split T4 flanged turbos in his own RB26 powered R14 so he can tell pretty you much exactly what to expect (I'm pretty sure they do their own in house engine dyno work as well) . Anyway talk to him because he spent 5 yrs doing Mechanical Engineering expressly to build a business making and marketing better aftermarket turbo systems components . He'll probably suggest using a Garrett GT4088R which has been designed from the ground up as a twin scroll turbocharger , with the right mix of bits these turbos are know to give large (not huge) turbo performance without initially feeling like everyone thinks a large turbo should . They are good at making a lot of mid range and I think very usable top end which is what your going to need to take on 5.7 - 6L V8's . I know he likes to use what most people consider too much in the way of external waste gates (2 on a twin scroll manifold) but the pressure/flow rate of exhaust gas in a properly developed twin scroll system has different characteristics so needs different components . Basically the exhaust manifold pressure is lower so larger valves are needed to vent the excess exhaust gas to control turbine speed . With our Pacific Paseo looking better on the greenback its a good time to check it all out . All that aside don't forget your going to need some very stout clutch and transmission components to make it all survive drag racing abuse . Godzilla was never designed to be a drag weapon and more of a tarmack racer that was toned back for street use . It did what it was designed to do which was win its class in Grp A and a few spacific Jap tarmack classes . If you look around the world others are getting good results drag racing smaller lighter AWD turbo terrors so thats worth some thought as well . Personally I think the Skyline GTR was designed to be a GT car and forcing it into a drag role kills off the essence of what it was intended to be . As is obvious I'm not into drag - in any form ... My 2c spent , A .

Hi all , I'm not sure if Garrett market a ball bearing version of the T51R except through HKS . This is way too much turbo for 400Kw IMO so I wouldn't burn too much time looking at them . I think differently now about the single / twin turbo debate on RB26's mainly because of the cost and effort to change them . Good reasons do exist for going the single route but I think they are competition related and real race cars usually have the budget to match . I'll be blunt here but at the same time this is not an attack on any one individual . Many single turbo manifolds are absolute garbage and people don't want to spend the money on those that really make the twin scroll single turbo work as well or better than the factory short branch manifolds and parallel twin turbos . Basically you gets given a choise with the 26 head , tear up 5-7 approx grand on the gun manifold/turbo/gates or fit appropriately sized aftermarket bolt on type RB 26 twins . Even at 2G each your going to be better off financially and it'll look sort of factory , no externals to try and convince the cops it just has big EGR valves .... For the power you want it'll be easier for you if the cylinder head is modified properly and suitable cams fitted , the std head lacks breathing on the exhaust side and mildish cams help give them larger lungs . At least the RB26's six throttle inlet system helps takes the chaff cutter effect (reversion) out of longer period cams . I look at it this way , I'd only want to have a GTR in bits once so it would be head off meaning you can get at the crowded TT side . I'd have the head ported and buy mild cams , smooth up the std manifolds and buy suitable turbos such as 2530's or equal . Good split dumps seem to make a worthwhile difference so buy them too . If its possible to simplify the factory plumbing and mike minor alterations to the fastening systems thats worth a look because GTR's are a bitch to work around on the turbo side . Then assemble and tune and be happy . I would not lose any sleep if it only got 385 Kw because the last kw/nm don't get used all that often . I believe having a usable power range is an exercise in sanity and far more practicle than having one high number . I probably shouldn't ask but is there any particular reason for wanting 400 Kw ? I'd consider 300-350 plenty for a street car and I think you can get a far more usable power range with the headwork/cams/mild turbos such as GT-SS's or the Garrett marketed version . I think you can make a mildly modded GTR go better everywhere than a std one particularly at around town speeds and revs . Its the low to mid range punch that the earlier GTR's seem to lack and why I reckon I see so many "idled" around at 3500 revs and given the gas from there just to get some shove in the back . Its the legacy of being a heavy homologation special and having less capacity because of the turbo multiplication factor . Your money , your call . Cheers A .

IMO the only way to get the best from an RB30 is with an RB26 head . Std and aftermarket GTR cams are set up to work with the RB26's six throttle inlet manifold system and thats why they can cope with the increased overlap . When you use a single throttle per cylinder system the plates block the positive pressure reversion pulse you get from reflecting back into the plenum chamber when using greater overlap and longer period cams . So the multi throttle system gives the least throttling losses and copes far better with reversion which is the mark of a competition engine . Broken record I know , do something with the head stud holes and the 26 head falls on . Almost always the best manifolds for super duty engines are for the hottest one out of the box - RB26 in the RB family . Heaps of cam/valve/spring options . For the best from a T04Z your going to need a divided T4 flanged manifold (and housing) because you won't get the gas flow through a T3 flange no matter what sized housing it has - particularly with 3L in front of it . If it were me I'd sell the Neo head and that won't be hard to do because they are not like grass seeds , and buy an RB26 head . RB25 heads in a way are a big PITA , people want to fit GTR spec cams / adapt the GTR inlet manifold / exhaust manifold/s and end up spending more money than the right head costs . The 25's VCT is a pain to work around and has no place in a high RPM engine . Your call , I know what I'd do . Cheers A .

IMO the only way to get the best from an RB30 is with an RB26 head . Std and aftermarket GTR cams are set up to work with the RB26's six throttle inlet manifold system and thats why they can cope with the increased overlap . When you use a single throttle per cylinder system the plates block the positive pressure reversion pulse you get from reflecting back into the plenum chamber when using greater overlap and longer period cams . So the multi throttle system gives the least throttling losses and copes far better with reversion which is the mark of a competition engine . Broken record I know , do something with the head stud holes and the 26 head falls on . Almost always the best manifolds for super duty engines are for the hottest one out of the box - RB26 in the RB family . Heaps of cam/valve/spring options . For the best from a T04Z your going to need a divided T4 flanged manifold (and housing) because you won't get the gas flow through a T3 flange no matter what sized housing it has - particularly with 3L in front of it . If it were me I'd sell the Neo head and that won't be hard to do because they are not like grass seeds , and buy an RB26 head . RB25 heads in a way are a big PITA , people want to fit GTR spec cams / adapt the GTR inlet manifold / exhaust manifold/s and end up spending more money than the right head costs . The 25's VCT is a pain to work around and has no place in a high RPM engine . Your call , I know what I'd do . Cheers A .

Ta . As per the single on RB26 the things to know are : 1) What state of tune and condition the engines in . 2) What style of manifold and wastegate system . 3) Intended use - what engine range the thing needs to have acceptable torque over . 4) Budget . Pointless without one . Cheers .

I had a look at their site recently , it sort of looks like a swag of T31 turbines and P's with a choice of T04S or I think the T04R compressor . I gather thats what you mean by Z wheel , the T04R's compressor . I think I can see why some of these turbos are making a name , T series turbines with T series compressor wheels like Garrett intended . One combination I saw that worked well on SOHC RB30's was the P/60-1 and the 1.00 A/R TS T3 flanged T4 turbine housing . You can now buy the P/60-1 reasonably cheaply (for their large frame BB centre section) and the old housings bolt straight up . Cheers A .

The std bar is made of spring steel to have a bit of give .

The F3 or Formula Pacific head is expensive and very extreme cam wise for anything on the street . A couple of years ago I found a thread on some US board about converting a KA24DE head to an L series 4 . At least the bore centres are right and I think the stud holes may be close or same . The problems from memory were always going to be the cam drive chain and timing cover . I guess with enough money you'd get it to work but then again a de stroked KA DE short with longer rods may be cheaper and easier if you wanted to rev it . Can buy turbo exhaust manifolds and better cams/springs over there from JWT and probably others nowdays . Pretty sure KA and SR use the same bellhousing pattern as well . Good to see the big fella back , cheers Adrian .

I'd say the expense is because they have more tubes and it takes longer to weld the plate to the core if its been cut from a large piece of core material . In a Skyline I suppose the core would need to be reasonably tall so that the tanks didn't disrupt too much airflow from the condenser and radiator . Cheers A .

Thats not straightforward question . Yes the faster you turn an engine the closer "time" wise the pulses become . From a mechanical point of veiw it doesn't change no matter how fast you turn it . The crank pins will always be the same number of degrees apart . A V12 like any other multi cylinder engine will be affected by how its manifolds are designed . If every inlet and exhaust tract is completly seperate then its cylinders won't be robbed by the others . In a turbo application obviously the exhausts have to be ducted into a turbo or turbos , I'm not quite sure of what their firing order is and to be optimul the exhaust manifolds would have to be designed around that . Possibly four turbos and four three branch manifolds may work but I somehow doubt the firing order would make the groupings right . Older aero engines like Merlins and Griffons used mechanically driven multi stage rotary compressors so exhaust was no issue . The V block configuration changes everything again compared to an inline one . Usually a V engine has its inlet ports facing the middle and obviously the valley cover becomes the inlet manifold . The exhaust ports face outwards so you'll have two six port exhaust manifolds . How they get around exhaust pulse timing I'm not sure . The only V12's and V16's I've had anything to do with are locomotive diesels and they have the exhausts in the middle and airboxes on the outsides of seperate cylinder heads . These things are slow reving ie around 900 for a GM or 1100 for a GE and as you could imagine throttle response is very slow compared to anything automotive . Getting OT but nowdays the Americans are opting for V12's with larger pots to develop their 43-4500 Hp and the advantages are a lot less moving parts and a shorter possibly lighter prime mover . Manufacturers have lots of reasons for deciding on how many cylinders and in what configuration . Their last consideration is what we as petrol heads can get out of it . All they want is cheap clean and economical - mostly . Cheers A .

My 2c , laminer flow because the shortest distance between two points is the direct path . Turbulent air or fliud has to go further because the direction its moving in is not necessarily the shortest distance if you know what I mean . Barrier flow . Fluid/gas tends to form a slow or non moving layer against a rough surface and it sort of lubricates the main flow mass from the barriers surface . Heat exchangers such as intercoolers/coolant radiators/oil coolers have "turbulators" inside their tubes to add a lot of surface area for extra exposure to the gas/liquid beeing cooled . Its the reason why a core with lots of narrow tubes works better than a core with fewer large tubes - note intercoolers made from truck cores with large tubes , great for flow but often not the best for heat transfer . The effects of swirl and fuel/air mixing is largely up to how the ports and valves are designed - most production inlet manifolds seem to have the injectors close to the head so much of the inlet manifold is said to be "dry" air only . Wet systems ie single point EFI or Carburettor/s have a few more issues with keeping the fuel in suspension with the charge air . There are some big advantages with GDI or gasoline direct injection because the system become more like a Diesel in that the whole inlet tract is dry . You don't have to time the injection to have any bearing on fuel being carried into the cylinders - its already there . There is also the sizable advantage of being able to control inlet air throttling purely with the inlet valves though thats pretty complex in itself . More potential VE . Cheers A .

Hi Roy , yeah out muscling an FJ20 with an RB20 would be very difficult . The FJ was a pretty good combination of bore and stroke (89 x 80) and rods were 140 odd mm between centers . The big bore means you can fit larger valves in the chambers before they come close to the bores . The FJ20 being a production engine a had wider included angle between the inlet and exhaust valves than say a Cosworth BDA which makes for a deeper chamber - more steeply angled chalet roof shape . compact chambers are supposed to have anti detonation advantages and its easier to make CR alterations with piston crown variations . The world changes dramatically when you go to six inline cylinders . The I4 has a flat plane crank so the number of crank degrees between cycles or power strokes is 180 deg . The I6 is more like two I3's joined together and the crank phasing is 120 deg between cycles . Now the RB20 has 6 333 odd cc pots compared to the FJ's 4 497 cc pots so the 4 clinder with generate greater power from its larger pots . The power cycles have less overlap being 180 vs 120 phasing so theres going to be less time for the next and last cylinder to interfere with its induction and blow down phases . You would have to know my opinions on the whole split pulse/twin scroll turbo set up and an interisting thing is that the TS system works a little better on an I4 than an I6 . This is because a TS I4 has 2 cylinders venting into each side 180 crank degrees apart where an I6 has 3 cylinders into each side 120 degrees apart . There probably was good marketing reasons for going with an I6 - 6 always sounds more than 4 even if the cubes are the same so good for marketing a sporty car . Depending on a few things an I6 can be a smoother running engine than an I4 so some say this adds "sophistication" to the vehicle . To a degree I like big I4's but packaging them and having nice bore/stroke and rod/stroke ratios seems to be one the manufactures want to baulk at . Such is life . As for TT's on an RB20 thats a big ask . I'd prefer the twin scroll single turbo system because it works out simpler - TT's on an RB20 is not really economic because the RB26 manifolds don't bolt up and I think the effort to make it work tip the balance in favour of the TS system . To go either way properly would not really be viable unless the user had to stay with the RB20 and could not use an RB25/26/30 . To make an RB20 strong means to have more air forced into its cylinders earlier and have the absolute minimum of exhaust manifold pressure but with reasonably good turbine response . This is all about raising the volumetric efficiency of the thing earlier in its rev range to make usable torque before its limited breathing abilities become the limiting factor . The Budget . Spent ~ 2300 on a FullRace manifold/~ 1600 the turbo/? the waste gate/? the plumbing and get it all fitted . So for something up to ~ 5 + grand is anyone interested ? Cheers A .

Yes I'd been thinking about Corkys ideas from Maximum Boost and the APS V8 and V6 intercoolers . I did wonder about 3 or so R33 25 SMIC cores welded together but need to have a look at my R33 IC . I'm sort of interested in the idea of the top and bottom tank fittings facing where the SMIC lives so the plumbing should not be too dificult . It also sort of ends the immediate need for the inlet manifold to have a forward facing TB . I've been wondering for some time how several TB's would gop insted of the RB25's single . Out of time , cheers A .

Hi all , I've noticed that some firms overseas are beginning to use vertical flow FMIC's - that is a greater number of shorter tubes rather than a lower number of longer tubes . I remember about 7 yrs ago one of the Rigolli's had Plasmaman fab such an intercooler for a Lancer GSR drag car and while expensive was quite effective . It occurs to me that people have issues with long pipes in the engine bay of single turbo R32/33/34 Skylines , so if a vertical flow IC was made with the ducts at the ends of the tanks facing the displaced SMIC it could work well and not be as glaringly obvious as the typical bend off the TB and down through the sheetmetalwork on the drivers side . More tonight on my opinions of vertical flow intercoolers and why I think they work better . The Icing on the cake is that the tanks can be quite agricultural and still work well . Opinions ? Cheers A .

And no split external waste gate mount . You're going to find that its the pressure drop over each manifold runner thats important not its constant flow rate . Piston engines don't have a constant gas flow rate on either side because the valves are opening and closing . However if the cylinders feel a consistant pressure drop through the exhaust manifold it tends to equalise their flow velocity and thats what the engine and turbo prefer . What the HKS manifold also does is angle the compressor end of the turbo away from the block so packaging is a bit easier . Also if you drill/tap the four extra holes you can use a T4 flanged single/twin entry turbine housing . The RB26 version suits only the T4 flange size . Cheers A .

Just to quantify , far better cam profiles available for the non hydraulic bucket RB heads plus springs etc etc . The RB26 head also happens to have the matching stud patterns for the highest performance factory manifolds available which is important where budget is a big issue . I was going to suggest 26 internals in a 25DE block but deleted that because if aftermarket rods and pistons are needed then might as well plonk the 26 top on an RB30 block . There really is no cheap way to make the power from an RB 6 , I really think the 26 head is the solution and the more cubic inches you can put under it the less revs you'll need to get the ponies . I wouldn't waste time and money on an R33 RB25 head because the valve train wont hack the sort of valve actuation necessary to make the engine breathe in and out . You really need that 26 head and all 3 manifolds . Cheers A .

I reckon I do . Firstly that turbo in the pictures is not using the 700177-5023 cartridge . Its compressor looks like the evil 7/14 blade T04S type so it won't be a 71.1 mm OD GT35 family comp wheel . Can't be bothered going into all the nitty gritty again but sufficient to say that a 76mm OD compressor won't like working with the Hitachi comp housing . The Hitachi exhaust housing and GT30 turbines are not the best bed mates either . Both wheels really need housings that can support more flow to give off their best . I think the real 0.63 GT3071R in its native 0.63 A/R turbine housing would be a better all round turbo on an RB25DET . Cheers A .

Yes they are costly but then not all manifolds are created equally . For the dough you get thick walled stainless pipe , like that used in nuclear power station cooling systems , and a properly designed and fabricated merged collector . If you ask he'll tell you that its equal pressure drop over the six individual runners thats important not just equal length . Sad fact of life is you build won't be a budget one and if lifting the head off is an issue then you may be aiming too high . For the power you want I think you should be looking into components that will do the job easily enough rather than those that could be not up to the task . Don't forget your asking for more than double the advertised ponies the original RB26 put out and production engines can only take so much . This is why I said I'd start with an RB26 because they got all the factory goodies std so they make a far better basis for high power capacity . Plenty of people have paint themselves into corners attempting to get high outputs from RB25's and the outcome is always the same . "I wish I'd started with an RB26" at least the head/inlet system anyway . Something else to think about , particularly if FR's manifold is too costly for you , is using the RB26's twin parallel turbos . Good bolt on ones are easy enough to get and they eliminate the external gate issues you have with large twin scroll singles . A pair of 2530's or similar with reworked std manifolds/good dumps/properly modified head/suitable cams should get close to the ask , using the greatest number of std or std replacemebt components . Wherever possible factory engineering generally makes the most cost effective upgrade because it was mass produced and benefits from economies of scale . Custom bits kill your budget because the labor costs involved . Anyhow its your call , I'd just hate to see you get the power and blow the thing to smithereens . No money and a pile of scrap . A .

Should have been in FI but to give closure . Neo RB25DET IMO has advantages in its non hydraulic buckets , it allows you to use aftermarket cams with bias towards performance rather than just surviving with hydraulic buckets . Also the CAS is a more accurate thing though may not be an issue for you . Younger engine so less used up . Cheers A . To go any further this thread should be transfered to FI .

Its funny you should ask about GT40's vs GT3582R's because that exact debate is going on at a few boards in the US . If you are really serious about the 600-650 wheel Hp and if your are prepared to go to the trouble and expense to do it properly then the GT4088R would be my choise . Before that though I think I would be putting the money into an RB26 because the head and inlet manifold is a better basis to start with . The hydraulic buckets in an R33 type RB25 engine are all about being quiet and maintenance free so really far from the best thing in your application . Also better cam profiles are available for RB26 heads than R33 25's . Geoff Raicer from FullRace Motorsport makes arguably the best turbo exhaust manifolds money can buy and they'll bolt onto RB25 and RB26 heads . They've had a lot to do with Garretts GT4088R turbo and their trademark is being able to fit largish turbos to engines without having that innitial large turbo feel real world . You would also benefit from his personal experience because he likes the GTR's drive train enough to graft it into an S14 (US 240 SX which he calls R14) , he's no stranger to RB26's and PROPERLY designed twin scroll turbo systems . I suggest you search the FullRace Motorsport website and it has a forum at thar site . Yours is not going to be a cheap build so I hope you have a healthy budget for it . Cheers A .

A GT2860RS is very similar to the HKS spec Garrett GT2530 , all its missing is an RB specific T3 flanged GT28 turbine housing which HKS had made for their RB specific version of the GT2530 . The real GT3071R (cartridge no 700177-5023) is a step up in turbine and compressor size and in its smallest available 0.63 A/R integral gate turbine housing may be ok - at least its the propper non cropped GT30 turbine in its matching factory GT30 turbine housing and integral wastegate . To keep its external dimensions a little smaller you could possibly ask for one of these to be supplied with a T04B rather than T04E compressor cover . For a buy/bolt turbo the real GT3071R is probably the go for an enthusiastically driven car . For best results you MUST insist on that 700177-5023 cartridge (centre housing and wheels) and MUST use the genuine Garrett GT30 integral wastegate exhaust housing . If you get sold smilar cartridges with cropped turbines and aftermarket exhaust housings (or modified OEM) then the result will suffer . You have to insist on the right bits to have any hope of it working as the design engineers intended , to the point where you won't discuss any variations on the real one . I know this sounds harsh but when buying tyres they're all black and made of rubber - they don't all work the same though do they . Your bux your call , cheers A .

The first thing to work out is if the comp housing is turning on its backplate or if the housing and backplate are rotating on the front of the bearing housing . It would help to know what kind of turbo it is too because for example some Garrett GT BB turbos fix the backplate to the bearing housing with a large circlip . Others like T3 or T4 based turbos have the backplate bolted to the front of the turbos bearing housing . Cheers A .

Mafia I agree , PFC and Injectors opens many doors and closes none . No real compromises so he won't be painting himself into any corners . Along with a slightly higher capacity pump this path has most roadies covered IMO . Cheers A .