discopotato03

Maybe what he is asking for is how can I have it a little better than it is now but don't want to lose much if any low down squirt . If this is the case it could be worth looking at the best factory offering (for road) which I suppose would be R34 type ball bearing turbos . Other than that if there's money to be spent on an internally std engine with mild cams most really like the HKS GT-SS turbos . I find people buy early GTR's and don't like what they think is peaky power delivery compared to N/A cars with a few more cubic inches . I could launch into a long spiel about GT28 BB turbos but all been said in the past along with many conflicting opinions . Cruiseliner has a long development string in here somewhere about his GTR and his HKS GT-SS turbos , with the mild mods he did he said the results were brilliant for what he used the car for - road from memmory . I'd PM him . Cheers A .

Me smells a port shrouded comp cover LOL . Cheers A .

Bush bearing turbochargers have to have a thrust bearing to stop the turbine/compressor assembly moving back and forth within the bearing housing - end float . So at the compressor end of the turbine shaft is a collar or cylindrical spacer with a square section groove machined into it . The front of the turbos bearing housing has a plate fixed to it and the shoulders of the thrust collar bear on it . Most turbos have this plate with a gap or slot in one side so that this thrust plate can be slid in between the shoulders of the collar at assembly time , once the bush bearings and their circlips are installed the turbine/shaft goes in then the thrust collar and plate . One of the down sides of bush bearing turbos in high speed high boost applications is that they get a fair bit of end float loading and the thrust bearing assembly doesn't have enough bearing area to be long term reliable . So usually the thrust plate suffers rapid wear allowing excessive end float and the wheels generally have a big "rub" on something and destroy themselves . These standard style thrust plates are said to be 270 degree and the full circle ones 360 degree . As a bit of a band aid upgrade the full circle ones have a bit more bearing area in the plate itself but its not really enough in the scheme of things . Their use means you have to have a two piece thrust collar to be able to assemble it . I'm not sure whats available now but in my time with bush turbos it meant having to use a carbon or dynamic compressor end seal which is not prefferable in a blow through EFI application because it adds drag for no very good reason . Speaking of drag you will get a little more oil shear drag with 360 degree thrust plates because thats the nature of the beast . Ball bearing turbos use annular contact ball races which means they support the turbine shaft against radial and end float loads . The fact that they do so with a fraction of the drag and much closer tolerances than bush turbos is a huge advantage . Bush turbos have a very short life in high shaft speed use because of the limitations of their bearing system . Todays modern wheels are designed to run faster than the ones they replaced which is why from an OEM perspective they can be compact and make quite reasonable torque/power . Cheers A .

Dale that 300 WHp was just a suggested number and I think I can do that and a bit more with better (for me) torque characteristics . Mine is not about a std engine , I don't particularly like the std characteristics of them and porting + mild cams should alter these to better suit me . Wildcat , yep exactly why I used that term - redneck cartridge . I don't necessarily agree that the GT30 turbine based turbos have to have the response penalty but more money and effort is needed to have ALL the benefits . Cheers A .

Hi Dale , a contact in the US (a very capable fabricater and tuner) has managed to get phenominal mid range torque like 400 ft/lbs at 4500 rpm from a developed SR20DET with the divided .78 A/R housing (see ATP Turbo.com for housing pic) and a real GT3071R . Everything about the turbocharger is std except the divided turbine housing which is T3 flanged and looks identical to the housing on the non gated Garrett GT32 series plain bearing turbos ie GT3267 and GT3271 (can see them at turbobygarrett.com/products/turbos etc) . He is saying that they are getting results previously thought impossible with that engine/engine speed . He thinks this is what I should run for a punchy responsive RB25 with about 300 wheel Hp . On the face of it 300 WHp may not sound like a lot but its the broad torque band I'm interested in , can anyone tell me what sort of WHp and torque numbers in ft/lbs good quality 235 width road radials can hold ? Cheers Adrian .

No Lithium neither , there have not been many of either of them out here until a year or so ago . Most had either the T04S compressors or the cropped turbine/wrong housing in the 3071R 's case . So no I can't tell you how the exact real word experience feels . I think Cubes and a few others understand what I call the windmill effect that good matching gives and thats what I want as well as good on boost torque . I have been there with engines where you had to chase the "boost curve" so that the thing would go if you prompted it , it ment driving round at higher revs and lower gears which wears a bit thin in time . My last engine/turbo did all that (windmill etc) and would pull strongly to about 6800 revs - plenty for me . Later .

Hi all , someone mentioned recently that the std R33 RB25 does its cam timing change at something like 2000 and 4700 rpm . I suppose it has the cams open situation (minimum overlap phasing) for cranking and low speeds . The poster mentioned that the cam phasing then closed at 2-4700 for performance reasons and then opened again to get around high "backpressure" at higher revs . I have to wonder how much of this has to to with Nissan playing games with internal exhaust gas recirculation for emissions reasons . I'm no automotive engineer but I would have thought that keeping the cam timing "open" at lowish revs and part throttle ie 2-3000 revs would pay off drivability wise . I can't see how you would not have a little reversion in these cases because the inlet side is below atmospheric pressure and lets face it the RB25's exhaust manifold and turbo are not the free est flowing items around . Also with better (less restrictive) turbos/manifolds/exhausts there could be some benefit from keeping the cams "closed" at full throttle a bit further up the engines rev range . For those using an Apexi PFC and tuning with Datalogit , can you tell me if its possible to control the cam change points based on airflow signals or are we stuck with just rpm setpoints ? For those using a PFC and Datalogit and the R34 RB25 it would be interesting to know what the factory did with its variable cam timing . Also of late Paul33 has been looking into loom adapting RB26 PFC's for RB20's and 25's and mentioned losing the ability for the computer to control VCT . My sinister mind is wondering if R34 25 VCT could be grafted to the R33's head and some third party controller used to call the shots . Its probably possible but I don't know what would work CAS wise having never seen either VCT system in bits . Anyhow just having control over the non variable R33 (powerglide VCT if you like) may prove interesting . Cheers Adrian .

Carburetted turbo setups are not nice but anyhow . You mentioned a "Blow Through" system which means the turbocharger literally blowing air through the carburettor and into the engine . When the carburettor is on the atmosphere side of the turbocharger (upstream) is is said to be suckthrough . Actually the term is nonsensical because the turbo can't "suck" , it can create a depression or area of lower pressure before the carburettor and then its up to the atmosphere to "push" the air through . Both systems are poor because . 1) Blow through : The whole carburettor/s need to be enclosed in a box so that positive pressure doesn't blow air out of every orifice the carby has ie throttle plate shaft/s . You have to pressurise the float bowl/s otherwise positive pressure blows fuel out the jets rather than the air stream drawing fuel in through the venturis . According to David Visard you need to put rings inside the throats of an open choke carburettor in an attempt to make it boost sensative . Different situation with constant depression carbs like SU's or CD Strombergs . Provided you get on top of all these issues its usually the better method . You don't have to bother with a carbon or dynamic (mechanical face seal) doing it this way provided the air filter has no noticable pressure drop . 2)"Suck Through" : This really is a crude read shitty system . The carburettor is upstream of the turbo so from its point of view it just has what it thinks is a larger engine drawing on it . It all gets bad because the throttle mechanism is upstream of the compressor housing so this see's lower than atmospheric pressure , lower pressure than is inside the turbos bearing housing so it tends to draw its lube oil out through the compressor end seal - if its a labirinth or piston ring type seal . Horror no 2 is that all of the engines air and fuel goes through the compressors housing and into the inlet manifold . Its all full of fuel vapor (wet systemn) so when you close the throttle its impossible to stop the engine running filthy rich on the over run . No3 , you have to then feed lots of fuel back in when you open the throttle in an attemp to get around the lean or flat spot . Very poor mixture control is the result . Single carb inlet manifolds are usually very crude and even then stupid things like overly rich mixtures are needed to cater for the worst fed cylinder . 4 Shoud the engine spit back or backfire there's lots of fuel and air in the inlet system and you can guess the result . Really either system is only good for mild performance increases and don't get anywhere near the result of blow through multipoint EFI . You would have to rate very crudly made inlet manifolds with the cheapest nastiest EFI system available as lightyears ahead of carburetted turbocharger systems . The fact that the conversion is going on an NA engine is a worry because they are very easily damaged in a boosted environment . My advise is don't do it , it will not be cheap/easy/effective so IMO not worth the effort . Your call .

Hi all , this GT3071R/GT3076R question is on the minds of a lot of RB25 owners so I can pass on what I know but have not been there - yet . I'm hearing tuners overseas say they think the GT3076R (the real one) is nothing special but much of their opinion are is going to be based around what they were trying to achieve and how they went about it . As I've said in the past I think the 52 comp trim version is probably a better turbine/compressor match but thats my gut feeling only . In the past reports about the GT3071R were a bit mixed and I think this is because its a bit of a wild cat or hybrid and likes things around it to be just so to suit it . Probably the hardest thing to get right is the exhaust manifold and turbine housing in order to get the compressor speed range to match the power requirements in the engines speed range . The gap in Garretts GT30 turbine housing A/R's is a little wide ie 0.63 and 0.82 A/R and something like HKS's .73 would lessen the compromises of the other two . What in my opinion people need to consider is what else they can do to to their particular combination to get positive results . As Gary (SK) has said things that let you push more ignition timing help out big time . It allows the engine to have its cylinders fired and pressurised so that it can make more torque before and after the onset of positive inlet manifold pressure . When you can do this it tends to pull down boost threshold so you get more earlier in the scheme of things . Having said that the same old gang rate a mention , tuning/intercooling/tuning/low restriction exhaust/tuning/cams tuning/headwork/tuning/effective exhaust manifold and wastegate/tuning tuning tuning . Really everytime anything is changed that affects how an engine breaths it needs the fuelling and timing checked . ATM I am very lucky (sometimes) to have the ear of a fellow who used to work in Garretts aftermarket section OS and hopefully he can point out to me the real world differences between the above mentioned turbos . So far I get the feeling that the GT3071R will allow the engine to pull from slightly lower revs which is logical given its slightly smaller diametre (71.1mm vs 76.2mm) compressor , and I think the fact that its compressor cover is 0.50 A/R compared to the 3076R's 0.60 A/R . On the nitty gritty side of things the 3071R's compressor is good for in theory ~ 44lbs airflow and the 3076R 52T ~ 49-50 lbs . The extra airflow comes at a cost and its the turbine power required to drive it . If the compressor makes life easy for the turbine the turbine creates less restriction for the engine and so it will make better part throttle squirt as well as come on stronger earlier when nailed . This is where the person making the changes has to decide what they want and live with the compromises . If I had to go out on a limb I would say that if you are not prepared to change many things go conservatine on the turbo and make sure that its compressor is a good match for its turbine . Bigish turbos on otherwise standard engines are cops because there is generally insufficient exhaust flow to drive them and even when they spool up the inlet restrictions make for high boost to get the performance . They tend to ber laggy down low , ok in the upper middle , and choked up high . I would like to add more about the twin scroll turbine housings but I'm out of time and fingers and probably mentioned most of it previously . Again comes back to how much time/effort/money you are prepaired to spend to get a good all round result . Cheers A .

Sorry , this was ment to be in forced induction .

Hi all , someone here mentioned that R33's are set up so the overlap is closed up for idle then opens up till about 4700 and closes to reduce reversion . I remember reading an article a few years back about JWT remaping an NA CA18 computer and noting that power fell off up near the red line . In this case the cams were opening up (reducing overlap) and the power falling off most likely to convince people to change up . I'm wondering how alterations to an RB25DET ie mild cams and efforts to reduce "backpressure" are affected by the std cam changeover points . I'd reckon the change back up high would not do any favours if there was not a lot of exhaust manifold pressure in relation to boost pressure . Has anyone played with the change points and gained anything worthwhile ? Cheers A .

FJ20's are getting to be an old world engine by todays standards and have a few things against them . I no longer miss the dinosaur management and ignition system or the overly complex double twin row cam drive system . They are heavy and bulky compared to most 2L turbo 4's and can create handling and cooling issues in smaller cars . The KA is based on closer L Series bore centres than FJ20's and has one single or twin row chain . The KA DOHC head casting is much simpler than the FJ's mainly due to improved casting techniques . I can't remember if they use hydraulic buckets or shims but they are a real twin cam ie direct cam loab on bucket like the FJ20 . To each there own but I think in the 2L vs 2.4L stakes the larger is going to be the better when it comes to making torque in a road car . Anyway bowing out here as I'm already way off topic . Cheers A .

For once I'll stick my ore in and please no offense ment . You mention that you have a 240 SX S14 so it would have had a KA24DE fitted std . These would have to be a fair bit lighter and obviously shorter than an RB25 for not much less capacty - I think there's about 60-70cc in it . A lot has been done and lots of goodies available for the KA 24DE in the US . Jeff Raicer from Full Race is making really nice exhaust manifolds for them and with current trends in twin scroll turbos they can make very strong torque from nowhere revs . With the right bits they easily rev to 6500 a pull like a locomotive . There are here and no doubt Stateside bellhousings for the larger gearbox so no issues with this . I guess the RB 6 in S 13/14/15 is appealing but the weight and bulk (and sometimes cooling) issues are not insignificant . Cut my tongue off but I'm even wondering what a properly developed Turbo or KA24DET would be like in an R33 . Food for thought . Donning flack vest and ducking , cheers A .

Frost no doubt someone will confirm/deny but I think all RB26 valve train components are unique dimensions . Your call but the head will most probably make/break the final result . R33 and 34 RB25 heads have larger ports than R32 RB25DE and I would think R33 RB25DE heads would not be very expensive anyway . I can't see why it wouldn't be possible to not use VVT with a 33 DE head plus you'll need springs anyway . I dont think the weld mod to the water jacket would be expensive . Just my 2c , cheers A .

Sold or not ? Cheers A .

Early RB26 and 25 pumps fit .

Hi all , I have zip interest in their turbos but some of the exhaust housings appear to be twin scroll or split pulsed . I tried searching for pics of the bum end of these units but got nowhere fast . I'm interested because twin entry T3 flanged turbine housings are not in good supply and could be an anternative to GT35 plain bearing or T04 housings for a twin scroll Garrett GT3582R . I think the KKR turbos (some of them anyway) are using a turbine with an OD of around 73mm which puts them somewhere in the GT37 - T04 area size wise ie between 72.5 and 74.4mm . Cheers A .

650 , may have a use but very expensive to make alterations to them . Your call .

Most Garrett GT BB cartridges have water cooling holes . If you spin the rotating assembly I think you'll pretty soon tell if its ball bearing . Also I'd look inside the oil drain hole to see if you can see the stationary cylindrical steel section of the bearing cartridge if it has one . Lastly the GT BB's just about always have an internally threaded inlet oil restrictor . I have on a PC pics of a bush bearing KAI's ID tag so will have to get back in a few days on that one . O/T I know but if looking to buy something do some searches on Garretts GT4094R because OS there are claims of ~ 900 Hp from that one in twin scroll (split pulse) form . Essentially the difference between a T51R KAI BB and a GT4294R (cartridge wise) is the turbine , 76T T51 conventional and 84T GT42 UHP . Garretts GT4088R is snapping at the heels of both with its 78T GT40 UHP turbine and in twin scroll form arguably better than the HKS T51 / single scroll pair . The GT4094R is outline identical to a GT4088R and in fact all thats changed is the compressor . Geoff Raicer is the one to talk to about these things . Cheers A .

PM me and I'll see if I can have a look at it in the near future . Cheers A .

I made some inquiries about that thing , turbine and housing are not high temp like petrol engine turbos so limited life in a high performance petrol app . The same thing can be achieved by using a GT35BB turbine in a GT3076R 52 compressor trim . That would also get you the single entry T3 flange as well as the Ni Resist housing and Inconnel turbine . Cheers .

Hi , I went through that situ recently with a late new R33GTST PFC Boost Kit . Because I hate hacking the cars loom I cut the standard wire between the plug and the factory solenoid valve . I think the wires were connected dark to dark for the earth side . My boost kit came with a long generic extention cord that had a white plastic plug with 90 deg oriented male spades . I simply crimped two female spades to the remaining section of original solenoid wire . It means having about 3 ft of wire coiled up (cable tied neatly) behing the airbox but it saves whimps like me cutting anything I dont have to . I need to make a flat plate that extends the bracket where the std solenoid sat to mount the Apexi solenoid valve . I could not find any way to mount the new valve in the std posi with the std airbox in place . To revert back to the std ECU/valve use the male crimp spades on the solenoid half of its wires so it could plug back in . IMPORTANT NOTE !!! If your R33 GTST hade the permanent earth mod to be in "high boost" all the time disconnect the earth . If you don't do this to a modded car the solenoid vale stays shut and it will boost untill it breaks something or in my case boost cuts . BTW you can cable tie the map sensor to the std boost gauges map sensor mount bracket , sounds dodgy but works and good stealth value . Run the cable along the firewall , mines cable tied to some convienent steel tubes and drops down to where the main loom goes through the firewall in front of the ECU area . I pierced the gromet and fed the small plug through to the PFC box itself . A little bit of black silastic on the gromet would probably help stop it from tearing and letting water run down to the computer . Have fun cheers A .

Also the oil inlet hole at the top should be one tapped one with a mushroom shaped insert inside it , not two tapped and one larger plain one in between them . Cheers A .

May I have a pic of the back ie turbine side showing the whole of the rear of the housing . Also may I have the numbers off its ID tag to confirm the cartridges wheels/trims . Cheers A .

Hi Goeff , willing to sell just the steel fuel rail and FPR ie no injectors ? Cheers Adrian .