discopotato03

One solution is JE forged VG30DETT pistons at 87.5mm . The gudgeon pins are larger so rods need work . If boost pressure is a measure of resistance to airflow then high boost is a lame excuse to get more air in . If you reduce the resistance to flow then same volume at lower pressure will make everything else easier . High boost pressure needs high fuel rail pressure/expensive pumps/expensive fuels/etc . The RS500 YBD engine had a dog of a turbo making an unreliable pig of an engine for road or Grp A . You need to look at better examples than this . Cheers A .

Yes true , but the cartridge (wheels) seem to be the same . The thing to look into is what Garrett offer in the way of exhaust housings , the HKS version is not like normal twin entry turbine housings - the divider does not go all the way around the inside of the volute or internal passage . If you look at the pics of the HKS housing the outside of the volute is quite narrow for the flanges dimensions and inlet holes . To get the housing to flow the gas the nozzle section must be wide meaning greater turbine tip height . I'd say this must be why they chose to use the larger TO4 sized flange rather than a more compact T3 twin entry type . Provided Garretts twin entry housings are similar style they should do similar things for the same ARR . Notice the difference in the compressor covers , big difference in size given that the same ARR is used for a wheel of the same basic dimensions . The port shroud design looks pretty and would not be hard for a machinist to copy . Still need to see the cartridge itself and the housings (esp exhaust) from the inside . Cheers from Parkes , A .

I found the HKS TO4Z Product Information blurb at http://www.roggan.net/TO4Z.pdf . Some interesting pics and graphs but sadly no compressor map . Cheers Adrian .

Your choise , I would not put diesel fuel anywhere near the sump . Diesel fuel is exactly that - fuel not lubricating oil so no guarantees it will lubricate . It will thin the oil down thats for sure . My own experience was to use diesel engine OIL but only because it was a high detergent type used in EMD/GE locomotive diesels . If I was you I'd run reasonable engine oil in it and change it and the oil frequently for a while . The only way without opening it up to remove gunge is by draining the oil and changing the oil filter . Cheers A .

Thank you also WetGTR , any chance of seeing the compressor and turbine wheels side on . From the cartridge number (740759-5002) both Garrett and HKS should be the same . Cheers Adrian .

If you're std turbo is in good nick you could fit the VG30/R34 RB25 Neo exhaust housing . Goes bolt to all std fittings and looks standard too , the trick is finding the housing . Cheers Adrian .

The 48T 446179-31 will be the most responsive anyway . It is the next step up from the GT28RS (2860RS) 446179-66 in terms of airflow and response . I'll take average power over a thimble full at the top end any day .

Hi StageZilla , I've only ever used ring/open ended spanniards for turbo housing bolts and never stripped or had any come loose . When brand spankers everything's clean particularly on the turbine side so no persuasuon is needed to remove its housing . Turbos are not short of clamping area so their fasteners don't need to be ridiculously tight especially on the compressor side (aluminium) . Most custom installations need them to be backed off enough to index the housings in relation to the core - the yanks call it clocking . The greatest danger is dropping the cartridge and bending the blades so this is a pre JD operation and need something soft to lay it on . Thanks for those pics , the things not as huge as I thought in relation to a standard GTR T28 . A T3 rather than T4 flange on the exhaust housing would have made it more compact again though HKS probably intend it to be an upgrade to to the T04R . Thanks heaps cheers Adrian .

Thanks guys good info . I have seen some pics of a version that may have a 7 blade compressor (well 7 full height and 7 splitter blades you'll know what i mean) so something to avoid . One of the sites mention a twin entry or split pulsed exhaust housing with a twin integral wastegate set up which could be handy if the turbine inlet pressures are not too high . StageZilla it would be VERY interesting to see the comp cover with the inlet snout unbolted to let on how they did the anti reversion holes/groove . Actually to see it in its raw glory ie housings removed would make the net zing ! Also has your's got HKS cast into the exhaust housing indicating a non Garrett special ? Cheers A .

Basically thats the one . I wish people would stop selling that GT25/T04S piece of crap , there's nothing 40 or GT40 about the compressor . HKS's version was slightly better (not much) because it used a small trim (46) T04"E" 6 bladed 76mm wheel but they wisely flicked it for a larger trim smaller O/D ie 52 trim 71mm BCI-18 (GT series) wheel . Its called a GT-RS or GT2871R in Garrett speak and can be had without the HKS ID or price tags . For anyone interested in the GT2871R series the turbo and cartridge (CHRA) numbers are as follows . 1) GT2871R 48T comp 49.19mm ind : unit no 743347-1 , CHRA no 446179-31 . 2) GT2871R 52T comp 51.20mm ind : unit no 472560-15 , CHRA no 446179-67 . 3) GT2871R 56T comp 53.13mm ind : unit no 743347-2 , CHRA no 446179-32 . The Garrett Site tells you the 2540R is not a performance turbo , more a display case racer . Cheers A .

I have done some searching but can't confirm if the wheels and trims are the same for the Garrett and HKS versions . I did follow a link to an E Bay Ad and it shows the cartridge ID tag but light too bright to read the numbers . HKS have obviously had their comp cover cast up so there may be differences other than the drilled snout air inlet . I'd like to see the cap screws and snout removed though the internal passages are probably not difficult to re create . None of the pics I've seen show the exhaust housing so I don't know if it's a special as well . Since the T04R's have been around for a while there must be some exhaust manifolds for the RB26 , would these be only tubular and hi mount ? In a perfect world cast iron and low mount may be more practical if such a turbo could fit down low in a Skylines engine bay . Lots of pics of Z's and their manifolds please and the ID tag numbers if possible . Cheers Adrian .

446179-0018 = 76mm 48T T04S compressor driven by 54mm 76T GT28 (NS111) turbine . Large diametre small trim dinosaur comp driven by small dia med trim GT turbine - sounds laggy to me . Along the lines of HKS's old superceeded GT2540R but worse - lower aero tech comp + non native turbine housing . Let us know how it goes . Cheers A .

From external dimensions how does a T04Z compare to a GT3540R , are these T04's generally a high mount turbo ? Cheers A .

I was reading the T04R turbo string and noticed a bit of interest in the T04Z Version . From HKS the Z version is as follows . Comp 84mm 63T in .70ARR housing . Turb 74.2mm 76T in .61/.81/1.00 ARR housing Claimed power is 700 Hp or PS . I think SK once said the Garrett GT3540R was good for around the same power so its interesting to note the differences . The T04Z uses an 84mm 63 trim comp where the GT40 side of the 3540R is 82mm 56 trim . The OD is not much different but the trim jump from 56 to 63 is pretty big and if the aero development is better the pumping efficiency could be as good or better . The turbine has gone up in size from 68mm (GT35) to 74.2mm but the trim has dropped from 84 to 76 . Its interesting to note that the wheel diametres make it like a scaled up 2530 and in the same trims too , 63 and 76 . The ratio of turbine to compressor major diametres are very similar as well at 88.3 and 89.6% . If Garrett have managed to develop highly efficient wheels and kept the innertia down this should be a good thing - I wanna to see the map too ! Cheers A .

So the T04Z's are doing it better than the GT3540R singles or 2530 twins for response and power . I'll start a new thread as I'm interested as well . Cheers adrian .

That cone shaped gadget is the top of a tubular device that locates in a hole through the bearing cartridge and I'm told doubles as the oil flow regulator or restrictor . Those who removed it found out the hard way what happens when the bearing cartridge shunts backwards and forwards letting the wheels get close up and personal with their housings . My personal experience is buy turbo , fit inverted flare adapter and plumb as for any other turbo . There used to be some pictures floating around the net of a sectioned BB turbo and you can see this hollow mushroom headed locating pin type thing in it . Cheers A .

If you can tap into the exhaust manifold somewhere and do a pressure test it should tell the story . Need to compare exhaust manifold to inlet manifold pressures . Cheers A .

T3/T4 hybrid turbos are a real snake pit . Their original aim was to have a light weight (when compared to T04) T3 based turbine and hang a SMALL trim usually T04E compressor and cover on the cold side . Back yard spares and Turbonetics take a look at them and decide that large trim compressors look much tougher and flog them off to the uninformed . Trouble is the poor little T3 turbine is going purple in the chops because the large trim compressor is trying to move the extra mass of air it can bite into . The other problem is Wallys back yard turbos insists on boring out T3 or Skyline turbine housings for bigger turbines - the nozzle inside the housing gets machined away which you can't see and generally lag and or surge is the result . The best T3/04E hybrids not surprisingly come from Garrett but for the money and real estate they take up the GTBB's do a better job . Cheers A .

Would I be right in thinking that a full flow oil cooler and a wide viscosity range synthetic oil eg Castrol R 10/60 would do the trick ie thinner at low temps and good lubricating over a very wide temperature range ? Cheers A .

I did buy an R32 box ages ago , I think the only difference is extra ribs on the bell housing . All else looked identical . Cheers A .

Yes interesting about the RB20 not having enough exhaust gas energy to cope with a .86 turbine housing . I guess the bottom line is that its not possible to have the broad flat torque line with 330 cc cylinders . SK did once say in an RB20 vs SR20 "debate" that the RB's advantage was that it could rev and so make the numbers . With the GT28RS .64 ARR hitting full boost at 3700 rpm it would be interesting to see what raised compression ratios could do before detonation became an issue . Another thing worth looking into is the GTS-R exhaust manifold , I'm not sure if the std 20/25 exhaust manifold is the same but if it is there could be some small gains in getting the gas speed right here . I think Joels 30DET Pdf shows some pics of RB20 ports but can't remember if the exhaust side are smaller than 25DET . Does anyone know if the factory did anything significant with the last of the RB20DET's ie R34 if there was such a thing ? If there is an RB20 Neo there's a fair chance Nissan was eager to get the most out of 2L so better manifolds or whatever may be available . Cheers A .

I can save you some trouble . Rb26 heads have non hydraulic lash adjustment which all other (except Neo RB25) have . They use solid inverted buckets with disc shaped shims underneath . The exhaust valves are sodium cooled and use different valve guides and seals (larger dia stems) . The manifold bolt patterns are different to suit the six throttle inlet on one side and twin turbo manifolds on the other . The exhaust side studs are 8 rather than 10mm . The front coolant passages are the same as RB30 blocks and R32 RB25DE blocks . Other ie R33/34 bolcks need mods to suit and oil supply for VVT blocked off . RB26 cams are the best factory ones .

This is aimed at the RB30DET users who are looking into Garretts GT3540R (GT3582R in Garrett speak) . I was looking through some of Garretts non BB GT turbos at the turbobygarrett site specifically the GT4082 and the GT3782 compressor maps . In order they use an 82mm 50T (.58ARR) and an 82mm 52T (.54ARR) . They are shown as BCI-18 meaning six blade GT compressors , I'm onto my contacts in the US to see if there are BB GT cartridges available with the GT35 turbine and 50 or 52 trim 82mm GT 40 compressors . Some like me don't want 6-700 Hp that the 56T wheel and .70ARR cover may give but like the big turbine the GT3540R has . I know HKS's 3040 uses an 82mm 50T GT 40 wheel in a .60 T04S cover so the bits are out there . It would be nice if the animal was available in a better spec though building another bitzer turbo would do if the parts could be found - may not be cheap though . Cheers A

Very small turbo and 12 runner inlet manifold - 2 feeding each pot and one with a throttle plate in it so that one could be closed at low engine speeds . At the time Nissan was trying to get some low speed torque out of a six with small 330 odd cc cylinders and low tech (ceramic turbine bush bearing) turbos . The R32 RB20DET is the pick as they're not that expensive and all the goodies come std . You may also be able to put the late head/manifolds/turbo on an R31 donk if you don't want to change the lot . What worked in the end was ball bearing Hitachi turbos with better response / better porting and inlet manifold design / more modern electronics ie ECU sensors and AFM . The later turbo for the early engine would be the best and easiest mod .

Have you got any pictures of it .