discopotato03

I'm not interested in doing this unless it can work completly like a GTR does and I think thats only possible with the sandwich adapter plates or an RB26 head , neither appeals to me . I have toyed with the idea of twin TB's on a std RB25 plenum chamber but you'd still have the plumbing over the cam covers . No I think the economics go with a GReddy type manifold on an RB25DET . Multiple throttling is nice but I can't see it being worth the cost and complexity of doing it to an R33 GTS25T , blame Nissan because they went to the effort to make it this difficult . A .

I'm not sure but Brett or Michael would be able to tell you , just thought it was a good opportunity . A .

Yes they are good , thank you . That second one reminded me that the air chamber is the vac source on an RB26 , I had not though of that with the RB25 ITB conversion setup . Cheers A .

I got an E Mail back from Rob - Anything is possible, its just time and money. We don't use idle valves ourselves but your best bet would be to remote mount a RB20 units and run hoses to them, not too hard to do at all and they'd fit under the 26 plenim. Does anyone have pics of the RB20 AAC/IAC housing so I can have a bit of an idea what they look like , and are they anything like the R33 RB25 one ? Cheers Adrian .

The RB20 compressor housing is smaller than the RB25 one so it may limit airflow a little on an RB25 . I'm a bit surprised they didn't ask about that if they knew it was going on an RB25 . It may be worth trying to find the right housing if you want all 43 beans out of it . If you can't PM me as I think I still have a VG30 BB one which from memory is the same casting as an RB25 one . I'll possibly be back at GCG on Monday so could drop it off . Cheers Adrian .

When you stick a BMW flat twin in your cars Rzz I'll think about it . LOL , cheers A .

Its not a case of being tight , its just extra money for a computer that has things a four cylinder can't use . The money would be better spent on other bits and pieces . A .

Yeah I just like the idea of being able to control idle speed hot or cold and not have to resort to screwing around with throttle plates . I have E mailed Rob so it will be interesting to see if he has an answer to this air by pass issue . Maybe he can fab something a bit more compact than Nissans system on the RB26 inner manifold and I can place the chamber and valves somewhere a bit more accessable than under the manifold . I went through the multiple SU and Weber carburettors thing years ago and don't want to go back with fuel injection . In time , cheers A .

This just gets harder to do "factory style" . I manage to search around and found a pic of an RB26 with the plenum and throttle plates removed so I could see the air chamber that is fed from the plenum chamber on one side and feeds through front and back facing hoses to two steel tubes runing up to an air log above the manifolds inner section . I'm not sure that this could be re created on an Rb25's lower manifold section but RIPs would be the one to know . I'm guessing that it may foul on the 25's side feed injector rail etc . All my 26 manifold stuff is burried under a wrecking yard ATM and I can't dig it out today , does anyone have pics of the RB26's inner manifold section bare ? RIPS has said that they don't bother with any of this stuff because with the computers they run they don't have a problem . I can't see how it would start cold real well without the Auxiliary Air Valve or how its going to idle at a constant speed without the Idle Air Control Valve - let alone when the Air Con cuts in . I want to run with an R33 PFC and side feed injectors but I don't see how it can all fit together like Nissan would/should have had it . Any ideas ? Cheers A .

If any of the dealers know if/when the V44 becomes available with peak and hold high current drivers let me know because I need a wire in computer . Cheers Adrian .

I searched but could not easily find pics of the underside of a complete RB26 inlet manifold . I need to see where the IAC and AAV are located - as in which part of the manifold the chamber is fixed to and how it accesses all six runners . I imagine that it must fit under and plumb into the inner section upstream of the butterfly's for idle speed control . If I know I can ask RIPS if this can be duplicated on his modified lower RB25 manifold so it works like an RB26 does . Cheers A .

A couple of things go against both the GT3076R and the GT3582R in their usual form . Firstly the turbine housings are not twin scroll and secondly the turbines and compressors in both cases are usually big trim sizes . They do quite well with big A/R turbine housings on them but thats not the way to go about making them responsive in the lower mid range . There are very few options with both of them and in most cases they are only compressor trim sizes ie 48/52/56T for the GT3076R and available from other GT BB turbos 50 and 54T for the GT40 compressor . Garrett has changed their thinking with turbine trim sizes but ATM thats only really available on the GT37xxR and GT4088R turbos , 78T instead of 84T . I had a quick sniff around some BW turbo specs mainly because Geoff mentioned a while back that some of their turbos are doing better than some GT BB Garretts and are cheaper to buy . I suspect that BW are using reasonably big diameter wheels in those turbos with big A/R turbine housings but with smaller trim sizes than most of Garretts GT series units . I guess the theory is big diameter wheels for large diameter diffusers and nozzles and with small/med trim sizes (inducers/exducers) to pick up efficiency and response . With big A/R housings it does make for a larger overall unit but if thats what it takes ... The small frame Garrett GT's (GT2554R-GT3582R) I think were intended to be as compact as possible as well as being a generation ahead of the T25-T04S range . What have I built , very little with my own hands because I have no workshop at home and revolving shiftwork makes it difficult at times . My old Subaru daily is a far cry from what I drove home from Melbourne two years ago . Its now AWD with close ratios and I dug up the highest spec variant of its engine in this land and had it rebuilt . Coated pistons/head porting/256 deg NA cams/bigger exhaust/massive anti roll bars (thanks SK)/Koni rear coil overs/five stud hub kit to fit which basically puts me into Impreza brake and wheel territory . The 13x5's will be replacede by 16x7's and the matching brakes from a MY00 Rex . Next on the list is an exhaust header because the factory one is garbage as is the tiny RHB52 VF2 turbo . I had GCG build up a spud spec turbo thats basically a GT2860RS but with the smaller GT2554Rs compressor wheel and housing and the smaller 0.64 turbine housing on the hot side . I still have to buy a wire in computer to replace the AM radio the engine lives with ATM and I'd like that to be a ViPec V44 , just waiting to see if they can do one for me with high current injector drivers . Then I can use FJ turbo 360cc squirters to replace the little 240cc std ones . Fuel pump was changed for a VL turbo one . My R33 hasn't got past the PFC and 34GTt IC yet but I had one of the Woolafs old heads ported and larger exhaust valves fitted by Harris , has Poncams in it too . GCG managed to get me a 52 comp trim GT3037 from Japan and the plan is to hang it off a HKS cast manifold I've had for a while . I've been talking to RIPS about a modified RB25 lower manifold modded to take GTR ITB's and hopefully into that will go a set of Nismo 740's I have too . Fingers crossed someone still has the R34 GTR IC for it and eventusally it will go in to . Recently the flywheel was lightened and Jim Berry did me a clutch for it which is really nice to drive . My 33 came with fresh SK type Whiteline/Bilstein suspension and a set of 17x8.5 Rays wheels and I had Michellin PP2's fitted so it points quite well . So lots a bits and lots to do , A .

Actually thinking about it Garrett are doing both the GT3071R and GT3076R in Evo 10 specific TS turbine housings and last time I asked him Geoff was impressed with their design - except for the gate issue . They are being cast and machined up in I think 0.73 and 0.94 A/R ratios - AND they're designed for an 84 trim GT30 UHP turbine not the diesel GT32 turbine like the 0.78 one is . An expensive option but a Garrett Evo GT30 housing with the gate sealed shut and external/s may be another option . I know you won't go the GtiR throttle system but just remember this , Nissan wanted that AWD Pulsar to be the Rally spec go getter and had the body and suspension been better thought out it could have been a lot better than it was - weight distribution and cooling issues were biggies though . With Rally throttle response is everything because when you flatten it often it means living or dying at the bleeding edge . The ITB's give you more of everything everywhere meaning torque and the point I'm making is its engine torque to get you cracking , it doesn't matter weather the torque comes from better breathing or a small turbo but having a tight leash on its delivery makes a huge difference . Really everything you are trying to do is tied to making good controllable torque over as wide a range as possible . Multiple throttling is effectively trying to do what twin scrolling is doing on the hot side , minimise interference from adjacent cylinders only this time its air going in instead of exhaust going out . Where you win is that you have very accurate control of airflow where having accurate controll of turbine speed is very complex and difficult to nail . Nissan were not stupid when they put the RB26 together and like the GTiR engine was aimed at homologation for competition cars . The 26 gets ITB's for very good reasons and the twin parallel dryers very closely mimic a twin scroll single , the twins make wastegating a snap on a production car and as we know don't work too foul on a real race car either . Imagine what a GTR would have felt like with say the BB VG30 single turbo and a plenum manifold with a single throttle body on the front . Really volumetric efficiency is everything and the higher it can be over as wider engine speed range as possible is what its all about . Please don't think I'm being negative but an SR20 in no exercise in engineering exellency , it achieved what Nissan wanted from it for a time but it is VERY much a compromise of a two litre four that can fall in length wise or cross wise (block length/height/bore size limitations) and a head that isn't really a hi speed thing valve train wise . There are going to be limits on how much capacity you can economically squeeze in because the block length and the rods short . So I believe the way to make them work is go for every VE advantage you can to get the most torque you can from them without turning huge revs . I'm not so sure the aluminium makes an SR20 light , I mob I knew roughly weighed a nude SR and an FJ20 and - the difference wasn't as much as they expected it to be . Everyones going to have their brand loyalties but being the sl*t that I am parts wise I think theres a lot to like about Mitsys 4G63 turbo engine , Geoffs had amasing power out of those things . Roy I know what you're saying about the AWD's making reasonable steerers look better but honestly 4/AWD can create nearly as many problems as it solves so need to be a super pilot to get the best from it . A .

TriniGT me too , just looking into the RB26 IAC/AAV stuff and the differences in the 26 type oil/water cooler . A .

Ah , no . If you want 300 plus Kw the one to have IMO is a GT3037/GT3076R as URAS mentioned . For whatever reasons the GT3071R has not really shaped up to be the GT3076R's little brother as in the 1000 revs lower boost threshold that a few mobs claimed when they first hit . Without being blunt I think the original poster has to look at the final result rather than thinking that if I spend a big wad of cash I have to have a big maximum power number to justify it . IMO there is more to be gained from properly sizing and tuning everything than the just 40-60 Kw more . Ideally you want the thing to be torquey/free revving/good throttle response/good turbine response/minimal restriction . This is why I'd start with the quad throttle inlet system , Nissan did it to the GTR (6) and GTiR and they would not have bothered if there was nothing in it . Also you don't want to confuse throttle response with turbine (turbo) response because they are two very different things . What the individual throttles do is make for a rapid pressure rise in the inlet manifold (up towards atmospheric) which brings the dynamic or effective compression ratio up quickly too . When you have a single throttle/plenum manifold you have four cylinders all demanding air from the one source so the pressure and dynamic CR transients will not be as fast . ITB's also allow you to run warmer cams than the single throttle ones and not get the reversion or hot cam cranky spluttering nonsense . I know that cam profiles and compression ratios are set for a reason but go look at std cam specs for say an S13 SR20DET and a GTiR SR20DET , ditto R33 RB25DET and RB26DETT . Geoff Raicer has worked with quite a few different manufacturers toys but I think the faves might be Nissan Mitsy and Subaru . You obviously know he does tasty bits for SR20DETs so you could do worse than to explain exactly what you want to do and ask him how he'd go about it . He'd know what spec engines he's had his exhaust manifolds on so he should be able to give you his personal findings . At this point in time I know he has been building manifolds to take the current Mitsy Evolution 10 turbos and importantly Garretts upgrade twin scroll GT3076R turbo for the Evo 10's . It's not impossible that he'd think a TS manifold made to suit that turbo would work well . The only issue could be that there have been some teething problems with the Garrett/Mitsy TS integral waste gate turbine housing but when they fix it the theory is will cream every other single scroll GT3076R out there and not be laggy . In the past some of the more successful GT3037 (satisfied) SR20 people in the US have used HKS's 0.73 A/R turbine housing (T28 flanged non gated thing) with good results . Garrett's T3 flanged GT30 turbine housings are either side of that A/R size at 0.63 and 0.82 , the largest 1.06 one would be too big IMO . Again no offense but trying to compare a Silvia to say an Evo 6 is like comparing apples to cricket balls . The Evo has short diffs and close ratios big IC/TS turbo etc etc etc . There will be limits to how much power a Silvia can put to the tarmac and making much more than that would be an exercise in frustration I think . Your calls , cheers A .

I think the thing to confirm is which "RB25DE" you are talking about as in R32 or R33 . For some reason I always thought that R33 RB25's were side feed injectors though not 100% certain about the non turbo one . Obviously the R33 RB26 was top feed . Cheers A .

You don't reckon 300Kw is a bit much from a 2L based four for track ? I'd be concerned that the power would be peaky and the usable rev range a bit narrow for most circuits . Not cheap but have you considered a GT2835 Pro S turbo ? The cropped GT30 turbine is fine as long as its in a GT30 based turbine housing which unfortunately only HKS make . Actually if you could rat up a T3 flanged Po S turbine housing the cartridge HKS uses can be bought through Garrett and on a four cylinder it shouldn't surge so possibly don't need HKS's compressor housing either . Anyway your call but you need to have power out of the slowest parts of the track as as wide a usable rev range as possible . Also peaky short power ranges force you to use expensive close ratio gear sets to stay on the boil . Controllable usable power you can get to the ground , better I think than a high peak number . Cheers A . Also you call but I wouldn't use anything less than the early head and the GTiR quad throttles , throttle response and least restriction throttling is everything for track .

I think the T in GTK might be worth a closer look at the turbine and compressor wheels , T series stuff is getting a little long in the tooth for many true petrol performance apps . I would have thought that something from the Garrett GT ball bearing range would be better for a two litre four - even a big bore one . What sort of power are you looking to crank out of your engine ? A .

Its not the compressor wheels that interest me so much , mainly that 60mm NS111 turbine . It is the center piece of that TR30R turbo family . I think I may have read once that its material is Mar M and not Inconnel like most of the production performance petrol app turbines . I'm not really for the "ese" copying it but if Garrett thought they were they might make it available themselves . Mongrels - its really not that hard to do , if they can get the larger trim and higher flowing GT30 UHP wheel on a GT28 shaft the TR30 one would not be any more difficult . Billet compressor wheels are overkill IMO unless you really are going to turn mega shaft revs and very high boost pressures like in a real competition application . A cast and machined compressor is far cheaper to produce in volume which is why most are made that way . There is the advantage of being able to make a customised or very low volume series of wheels from a billet on a five axis CNC mill because that's cheaper than making moulds and tooling up to cast them in low numbers . As far as the compressors bore hole is concerned they can machine virtually any size hole and even thread that will fit in the hub of the wheel without weakening it . Garrett's GT37 and GT40 compressors in the GT3076R and GT3582R (GT3840R) are designed to go in large frame diesel turbochargers and are usually larger thread bore wheels std . When Garrett chose to fit them in the two turbos I just mentioned they simply bore a smaller plain hole in the casting and face most of the hexagon off its nose . Actually the back spacing is altered as well but you get the picture . A .

I have four compressor maps from a couple of different diameter TR30R compressors ie a 40 and 56T 69.3mm one and a 40 and 56T 76.2mm one . They call the two 40T wheels BCCW5 and the 56T ones BCCW28 . Garrett mentions these four span a power range of 200-560 Hp which I take to mean the smallest 200 and the largest 560 . The maps for both 56T wheels look the goods and they show them pumping ~ 44 and 56 pounds respectively . It's maddening to think that the dimensions of some of these wheels is not drastically different to a real off the shelf GT3071R and what a turbo it could have been with the 60 mm NS111 turbine , available in 73 and 76T , and the 56T 69.3mm BCCW28 compressor wheel . They say every TR30R is an individual order and some of the major components can be had in Stainless or Titanium so strong and light . I imagine there are heaps of housing options so having 100 variations wouldn't be too difficult . I wonder if the _____se will ever copy them .....

I was wanting to run this type of system but with an R33 RB25DET PFC so I suppose the IAC has tp stay . Cheers A .

I've been trying to find out what people do about the Idle Air Control Valve/chamber and Auxilary Air Valve (cold idle up bypass) with these RB20 or RB25 to GTR throttles conversions . I gather that with the GTR ones under the manifold they foul on the RB25DET's oil cooler somehow , the 26 oil cooler must be different . Cheers A .

Sorry I don't know much about Greddy turbos - they are Mitsubishi based aren't they ? I prefer Garrett because I think their wheels are better designed for high performance petrol apps in the small/medium size ranges . They could offer a few more trim options at times though . In a way we are lucky that HKS played with some of them to better suit engine specific apps . They cost but they also generally deliver a known result and that can sometimes be better/cheaper than doing all the spanner and development work yourself . If they use Garretts own housings often they can be ordered through Garrett at a Garrett price as well , thats how I managed to get my GT3037/Gt3076R 52 trim port shrouded turbo . It doesn't have a HKS turbine housing but Garrett make quite adequate ones for my application anyway . You jusat have to be lucky and know the part numbers . I'm pretty sure you can buy a version of the GT2871R 52T (same cartridge as GTRS) with housings to suit an RB26 . The ducks guts would be that TR30R competition turbo (wheels actually) Garrett won't give us for sane money , two of those on an RB26 with suitable housings really would stop the rotation of the earth . Same turbine family as those in GT2530/GT2860RS/GTRS (9 bladed 54.4mm 76T) but in 60mm and 76 or 73 trim . Standard options have 5/10 bladed comp wheels but you could possibly pinch something from the 5/10 bladed Mitsubishi range to get close . I think Precision in the States sells those compressors . Most of the World Rally Car series ran a version of this TR30R and the Le Mans Audi R8 did well with a pair of them too . Interesting times .

If I was trying to get between a GT4088R and a GT4294R (assuming there is room to fit the larger turbo) there is a few avenues to look in . I don't remember off the top of my head the dimensions of the T51R's compressor and turbine but def worth a look . If you wanted to go inside and could get the bits maybe a GT4294R with the 52 trim compressor wheel . You could also look at some of the emerging BW amnd Holset turbos because at times they are viable alternatives to Garrett units . BTW the reason I don't like the idea of the 94mm GT compressor in the GT40 housing and backplate is because the set is designed to work with a set wheel diameter (88mm) and to machine it out for the 94mm wheel means reducing the effective diffuser area inside the comp housing . Same deal with the GT3540R (GT3582R)'s compressor in the T04S housing/backplate . These are bean counters decisions not engineers ones , I'm not saying they don't work at all but I am saying their performance is compromised . The real issue is pressure balance across the engine while the compromises involve try to spin the turbo up from low revs and light loads . I did read that he was building 3.3L RB engines from RB30's and you'd think that if everything including the fuel and tune was spot on it would fire up a GT4294R ok . BTW don't get sucked in by the American urban myth of that T04R compressor wheel being a "T67" , I think from memory its inducer measures ~ 66.7mm and the Americans truly love inducer size and don't seem overly worried about a compressors major diameter . To put you in the picture these are some figures of inducer and major or "exducer" diameters . GT3582R - 82mm 56T GT40 wheel - 61mm inducer . T04Z® - 84mm 63T T04R wheel - 66.7mm inducer . GT4088R - 88mm 52T C117 wheel - 63.5mm inducer . GT4094R - 94mm 52T GT wheel ---- 67.8mm inducer . GT4294R - 94mm 56T GT wheel ---- 70.3mm inducer . I think I did search before and the T51R's may have a slight advantage over the GT42R's because of its turbine trim which from memory is 56T , older aero wheel design but supposedly better response through a smaller than 84T sized exducer diameter . Note what I mentioned before about the GT4088R's 78T turbine which is why its response is closer to a 76T P trim turbine in a T04Z . I think you can even buy T51BB turbos through Garrett these days but naturally without HKS's specialised housings . Anyhow all this aside it does make a pair of GTRS's look easy especially with their integral waste gates and simplified twin manifolds . Possibly for a little more response and a bit less top end you could use the 48 compressor trim version of that cartridge - GT2871R 48T . Would all come back to engine size and how well it breathes I spose . My money on GTRS's , cheers A .

Boost and engine revs actually , you engine swallows more air at 10 lbs boost and 6000 revs than it does at 10 lbs boost and 4000 revs . To have the gas flows increase the wheel speeds have to as well . A .