discopotato03

Engine management and an exhaust manifold will be the hurdles on any L6 turbo - aside from the factory L20A-ET and L28ET . Interceptors would allow you to "bend" the airflow sensing device signal output so getting larger injectors to work acceptably should not be too difficult . What will throw a spanner in the works is the L24E's flap AFM because it probably won't handle enough air for a "forced" L24E . It may pay you to look into N/A L28 or FJ turbo AFM's because they should have adequate airflow capacity for a mild 2.4 turbo engine before they are fully open and no longer able to signal greater airflow . I have a feeling that early Nissan turbo engines like Z18ET and FJ20ET had the flap fully open before full power was developed and they pretty much just used the TPS and RPM signals to calculate their rich 10 odd to 1 full load AFR's . We're talking early 80's now and things were pretty crude compared to todays production car std's . It would pay to check if the N/A L28 distributor's vacuum advance can has any scope to work as a pressure retard system under boost . Actually if you really want to drag its engine control system out of the 80's into the late 80's anyway another option cold be to convert the dizzy/CAS from an RB30 to suit an L series and transfer the whole RB30 system . Luckily RB's and L series both use hose tail injectors and the only challenge should be the dizzy/CAS mechanical drive and the throttle body . RB 30ET's used a nock sensor too so a bit of thought would be needed to mount it in the right part of the block . The classic people will want to shoot me but really I can see a lot of money going into an old car and for the money I think an R32 would be preferable. What do you pay for a fair manual R32 GTST these days ? I can understand to a degree why the classic people hang onto some models like DR30's and PNE 2000GT's but IMO the L24E powered MR30 has too many old systems such as mac struts and semi trailing arm IRS (and that god awful link steering) to justify sinking money into . If the result is everything to you its time to update , my opinions only cheers A .

Craved the compressor map for the Garrett GT3082R (GT3040R) is the same as the GT3582R (GT3540R) because they both use the same compressor wheel and housing . You mentioned that your turbine housing A/R is 1.12 so if its a HKS GT3040 the compressor wheel is 50 rather than 56 trim so don't bother with the GT3582R's map . Garretts GT4082 map at the turbobygarrett site would possibly be closer though it uses a GT40 comp cover so who knows . I also think the wastegate size from boost pressure theory is hogwash . To a degree exhaust mass flow can be estimated from inlet air flow so basing wastegate size on on an inlet air flow reference seems more logical to me . H2K , yep a GT4088R is pretty big for an RB25 but for a large turbo its way to go I think . As Geoff Raicer would say they are useless in single scroll turbine housing form and are twin scroll standard . This forces you to use a T4 twin port flange exhaust manifold which is as it should be . Twin scroll turbo systems (I think anyway) change the whole world the engine see's on the exhaust side so what works with wastegates is also different . Geoff tends to use two external gates with his pulse divided exhaust manifolds (when cost is no issue) so obviously having a lot of valve area is not the issue it is with single scroll turbine housing set ups . I think the reason for this is that the divided manifold has greater pressure and flow fluctuations so you need greater bypass area to vent the gas when its under less pressure . The single scroll housing has more consistant pressure and flow across its single nozzle so if the gate use is too big the sudden pressure drop when it opens is going to cause the turbine (and therefore the compressor) speed wise to do eratic things . 2 more cents spent , cheers A .

Other issues past now , can you give me a bell . Cheers A .

With you combination of parts there is always this significant point to think about . Nissan designed that engine to have parallel turbochargers because it is a convienent way the group the front and rear cylinders and take advantage of the pulse effect - this is the way to have high exhaust gas flow and acceptable turbine response . Also having two integral wastegates means they have plenty of bypass area and the whole shooting match is compact - along the line of the engine for ease of packaging in a Skyline . When you go to a normally single scroll single turbocharger your tossing all the exhaust putts back into one area so you lose the multi passage effect and this will cost you turbine response . Its your call but if it were me I'd stick to either known parallel twins or a properly set up twin scroll single turbocharger . Given a choice I'd go a little higher than the factory 8.5:1 CR and juggle this with the specific turbo characteristics and the dynamic or effective compression ratio with better than standard camshafts . The things that will have the most say about how it drives just round the burbs will be turbine response/exhaust restriction/effective CR - and a tuner that knows their stuff .. Your call .

Nope no regrets . In a car of that weight strut front/semi trailing arm IRS and can't steer straight link steering is a real downer . Just about every aspect of R30's paints you into a corner and FJ20's are very crude electrically speaking . You learn to hate two twin row timing chains and the dizzy type CAS . We won't go into 4 stud hubs and disks that bolt behind them will we ... I didn't like to hear it at the time but someone here made it clear that the overall technology jump from R30/31 to R32 and later was "a quantam leap" . Very good advice .

Me too , I've got 2c to spend . Lets just say you have your engine running on boost and for whatever reason you leap off the go pedal . Inlet manifold and exhaust flow drops like a brick and for a very short time the turbos innertia will prevent it from stopping dead . What you now have is an area of higher pressure between the compressor outlet and the throttle plate/s and nowhere for the compressed volume to vent other than back towards the compressor . Rotary compressors are designed to be efficient in one airflow direction so they react badly when you get the reversal happening . Cavitation/hissys call it what you like but the compressor is definately in not happy Jan mode . Like some others I got to see the the technology change (84-96 era) going from a std engined Skyline DR30RS (FJ20ET) to a similar state R33 GTS25T . Like the RB30ET the FJ had no throttle closed recirculation valve (I'll call it TCRV) and it did make the flutter noise even with its std boost pressure of ~ 7 PSI . The thing I really did notice was the DR30 felt a little strange going from a loaded state ie 1/2 throttle to ALMOST closed , the residual pressure in the system gave a sort of delay to the engine unloading or backing off - unless the throttle was closed . The R33 does none of this and is quite responsive to rapid on/off throttle inputs . Now the load sensing devise is different in these cars the older being gate type AFM and the later Hotwire MAF . Unlike a MAP sensor these both react to mass air flow so are obviously upstream devices . If anything the MAP sensor is the one kept mostly in the dark because it can't see whats happening on the outside of the throttle plates so pressure out here means nothing to it . When you have a TCRV it becomes the "compressed volumes" escape route but I'd say its critical how its fed back into the system upstream of the compressor housing . A MAF sensor can only react to airflow throught it - so if it gets a sudden pressure rise on the engine side flow through it could slow or even pause . No airflow means no load signal so the ECU probably thinks fuel off and siesta time . I think it would pay to look at how Nissan set out their TCRV systems so that you can copy the positive aspects and avoid the stalling or fuel off antics . I think the bottom line is later RB powered cars use them so until they create a problem leave it as it is . Even the std one does the hiss thing with non std filters ie pods fitted . If I was going to do anything to mine I'd fit the twinned RB26 ones and call it a day , I believe it comes back to the airflow for power instead of boost for power because extra pressure brings extra dramas IMO . Almost forgot , later era cars are using higher boost pressure than FJ20ET/RB30ET cars did so the TCRV would have more potential to correct drivability glitches with rapid throttle inputs . 2c gone cheers A .

Search FullRace Motorsport and talk to Geoff in his own Q/A section .

Single mores the pity .

Can anyone tell me the numbers cast into the plastic sections of these hose tail injectors please . I'm trying to find out if FJ20ET are the same flow and resistance wise . Big D can you give us a call please , cheers A .

Cubes you may need to somehow probe the exhaust manifold for pressure readings and compare them to your inlet manifold pressure readings . I seem to remember people saying that the std type exhaust manifold may be hitting the wall at somewhere around 300 Kw . Also as you'd know not too many people have used a GT3076R on an RB30DET and the choice of turbine housing A/R would depend on what you wanted to achieve with your engine . In a crude sort of way its a bit like the RB25 ceramic BB turbo and its std turbine housing or the larger VG30 one . No question the 1.06 A/R GT30 IW housing would drop your turbine inlet pressure some but whats it going to do to your boost threshold . People with RB30's running GT35R's and the larger housing tell me that the boost threshold is around 32-3400 though this should be lower with a GT30R and similar sized turbine housing . Anyhow to your engine you have a couple of reasonably easy upgrades in cams springs and maybe a turbine housing . The thing you really need to know is that turbine inlet pressure because if its rising way out of proportion to inlet manifold pressure then thats a major problem . Also once you get some reasonably high boost pressure behind your inlet valves (particularly with NA springs) it wants to crack them open . Always something , cheers A .

I don't look very often at T04B compressor lists nowdays and my list of the 8/16 blade range isn't complete . I think I still have the hybrid I had built like that ages ago and I know it has the -24 comp wheel in it . If I get time I'll measure it up later but ~ 54 mm rings a bell . Similar sized 6/12 blade ones are 57 62 and 70 trims having 52.85 , 55.30 and 58.4mm inducer wheel sizes . The problem with using these T04B compressors in T3 or those Hitachi comp covers is that the inlet boss diametre (approx 60mm) is a little small for the larger trim inducer sizes and , you have to allow for housing clearance on the wheel and enough wall thickness on the boss to take the inlet duct without cracking or crushing it . Its the same deal if you use the RB25 compressor cover as I did on my hybrid . Some people have used the T04B comp cover and backplate on the T3 bearing housing as they bolt up ok . At least then you have a housing thats native to the compressor wheel . It really is hit and miss with these hybrids because so many different parts have been altered and the overall result can be hard to predict . You have to realise that to go down a development path costs money , to try 2 or 3 different compressor trims and couple of turbine housing A/R's means time and money and it gets tedious very quickly . If you have it I'd get the RB25 comp housing reprofiled to suit one of the 6/12 blade wheels run it and call it a day . Cheers A .

Yes compromise is the point to be sure . I don't look at the RB25 as being so much small though a little short on torque low down in the rev range when it comes to shifting a 1380 odd Kg R33 Skyline . Its more the power delivery characteristics that I would like to change . The thing you are going to find is that no matter which way you attack this problem its going to cost some reasonably serious money . If you put more cubic inches under it then thats a valid way to pull up the bottom end torque but is a fair bit of work and money . If you pull the head off it and do the ports/exhaust valves/cams also time and money . If you replace the exhaust manifold turbo and wastegate thats not cheap either . Its this wanting it on the cheap thats going to compromise the result . The major obstacles are the state of tune of the standard engine and what it takes to alter its characteristics . Now everyones budget is their own issue and the honest truth is that if they want serious grunt its available but in budget form not as nice as it could be . If you have to drive the thing every day and the dollars are short then I think the practical plan is to aim a little lower and give up the bit up high for a more even result everywhere else . Cheers A .

Well if you put either (3071R or 3076R) on an RB25DET with one of the larger A/R turbine housings you can make the power easily enough , but the low to mid range torque will suffer because the gas speed through the turbine nozzle wont be very high at lite loads . Dale you can't have it both ways with the conventional system . You either have the response from a smaller exhaust housing or the high flowing low pressure advantages of a large housing . I really can see why Nissan used the parallel twins on RB26's and this is another option if the cost of TS manifolds/ext gates/TS turbine housings is beyond reach . Neither system is cheap but the same basic advantages can be had either way . Real performance is rarely cheap , cheers A .

Gday Russ , welcome to the world of bastard hybrids . From the top , I reckon the compressor housing is a Hitachi HT- I think SS from a series 4 or 5 RX7 13B turbo engine . I'll bet the turbine is from the same . The bearing housing looks like a water cooled Garrett T3 and the turbine housing from a single turbo RB or VG ceramic BB turbo . The compressor wheel looks like a 70mm 8/16 blade Garrett T04B . Lastly the compressor end seal is a carbon or mechanical face seal . If it comes from South Aus there's a good chance that ATS built it . You call but I would not put the 8/16 blade T04B wheel back in it because it will almost certainly surge . Garrett also make 6/12 blade versions of that compressor wheel family and they would be the simplist cheapest fix for it . If you can measure the front or inducer diametre of that wheel I can look it up and tell you the closest match in the 6/12 blade wheels . From memory Bill Keen used to use either the -24 or -25 8/16 blade wheels possibly because these are the largest that would fit in the Hitachi compressor cover . What is this thing aimed at ? Cheers A .

I start too many fires don't I There are a few different versions of the "GT3071R" and they don't all use the same turbine . The good one is basically the real GT3076R but with a GT35 71mm compressor and a 0.50 A/R T04E compressor housing . The real GT3076R has the GT37 76mm compressor and a 0.60 A/R T04E compressor housing . From the maps of the as delivered GT3071R (real one) the compressor maxes out at 50 lbs corrected flow on one of my maps . This is in the T04E comp cover at ~ 3.2 pressure ratio or 2.2 Bar positive . At 2.2 PR/1.2 PR positive/20.5 lbs boost it shows around 46-7 lbs of air . The fluid dynamics people say that 1 lb of air can be used to make 11 Hp so thats how many work out the power potential of a turbo - but only from an air point of view . Don't forget the exhaust side . Real world the main differences between these (3076R/3071R) is that the larger compressor wants to pump more air for a given shaft speed than the smaller one . It also takes more turbine energy to drive than the smaller one so all else being equal it will bit a bit more lazy getting up to speed . Look at it like more gas (air) has more mass and in turn needs more shaft power to turn the compressor . If you read my past rantings you'll remember I said the GT3071R is a good combination but it's fickle with the choise of turbine housing A/R . This is because it needs a lot of compressor revs to deliver high airflow rates and reasonably high pressure ratios (boost pressure) to get there . To get good high end performance these turbos NEED a free flowing turbine housing section and low turbine inlet pressure (exhaust manifold pressure) . If you go the traditional route with a single scroll turbine housing its going to have to be a large one otherwise the turbine inlet pressure gets unacceptably high and this chokes the engine/turbo to the point where power hits the wall even if you can supress detonation . Judgement call , response vs top end . The reason Twin Scroll followers can get good power from these turbos is because they throw off most of the need some mid range response so can't get away with the large A/R single scroll turbine housing scenerio . With a propper Twin scroll housing you can have a largish A/R , pressure pulses timed to strike the turbine blades without having to fight their way through the artificially high pressure created by other cylinders . Anyway long story short you can have the turbos turbine reasonably large in relation to the compressor and not suffer the turbine lag penalty . Garrett have been building Diesel turbos like this for ages and most of them use TS turbine housings . They have things like GT3571's with the Diesel spec GT35 HP (high Pressure Ratio) turbine and the GT35 71.1mm compressor . They also have a GT3576/R with the GT35 HP turbine and the GT37 76.2mm compressor . Then you get into GT3776 and GT3782 (GT37 turbine is 72.5mm) with the GT37 76.2mm or GT40 82mm compressors like GT3076R and 3582R's use . The bottom line is if you want big engine torque from a smaller engine with about the best NA like characteristics possible then TS is the way to do it . Other than that put an LS1 in it . Cheers .

I don't want to sound negative but I think you'll find that the issue is rising turbine inlet pressure and its doing its best to overwhelm the wastegate valve and force it open . What happens is turbine inlet pressure rises out of proportion to boost pressure and all you have is the actuators spring load minus boost pressure to keep it shut . I've seen instances where enlarging the gates port and valve resulted in more area for exhaust manifold pressure to work on so it didnt achieve the desired outcome . Enlarging the gates area only really works if it formed a restriction . One idea I was looking into was using the 0.68 A/R HKS GT3037 Pro S turbine housing on a 52T GT3076R because its slightly larger (.68 vs .63) , has a better volute and nozzle shape , more direct wastegate path and a larger valve . The trouble is none of that is cheap and the .68 housing fell through . The word from FullRace Geoff is that the GT3071R in hybrid twin scroll form can get very close to 500 Hp with awesome response and low turbine inlet pressure so unless anything better materialises thats way to go for me . In fact 500's more than I really need so as long as its a responsive 350 + and free reving - all good . Cheers A

Hi , I'm unbiased with manufacturers so I'm curious to know a few things . Firstly is the car going to be a Nissan ie Skyline or is the drawcard having a large capacity RB engine for its own sake . The reason I ask is that it seems Nissan never intended the RB30 to be a high performance engine so there never was a twin cam head developed for it . I think the greatest limiting factor is going to be getting enough air in and exhaust out even with a modified RB26 head , the 3L brings obvious torque potential being ~ 20% larger but to make power at revs it has to breathe and with only atmo pressure to charge the cylinders I'm not sure if its possible to get enough valve and port area into an RB26 head . If you have choices there are other alternatives like 2JZ's and BMW etc straight sixes that are probably a bit less compromised than an NA RB2630 . Actually thinking about it if you look at Nissans V6's the bore was larger and the stroke shorter (ie VG30 is I think 83 stroke/87 bore) which in theory gives greater breathing abilities (can fit larger valves in greater sized bores) and the shorter stroke possibly means less piston innertia . The VG30 by todays standards is bulky and heavy and the VQ30's would have some design updates over the old 4 cam twin plenum VG30 . I'm pretty sure a few years back there was some form of VQ30 based competition engine and its results were very good . If it were me I'd research those before I put a lot of resources into a hybrid RB30 - particularly an NA one . Factory engineering is often hard to beat from a costing point of view so if you can benefit from their R and D so much the better . More than one way to crack the 3L nut , cheers A .

Roy that cast low split pulsed HKS manifold (RB20/25) has a larged machined pad where the turbo bolts to it . Its large enough for a T4 flange even though std it has the split T3 flange sized exhaust ports and stud pattern . To mount a Garrett GT3076R just bolt it up , it would pay to see if the housing needed a bit of grinding so that there is no step or overlap of the manifolds exhaust ports . Cubes did something like this recently with his GT3076R's exhaust housing when mounting it on his Nissan manifold . Just for the record I've never seen the turbo HKS intended for their manifold but , if the HKS spec FJ20 T04E is anything to go by it would just be a small/med trim T04E compressor on a smallish trim T04 turbine with a small A/R ratio T3 flanged T4 exhaust housing . Nothing to rave about . Your call but if I was using that manifold and an external gate there is NOOOOOOO way I'd use a single scroll turbine housing . Its been claimed by a very reliabe source in the US that the twin scroll version (hybrid) TS GT3071R can get reasonably close to 500 Hp if everything else is top notch . The TS version of the GT3076R I think nudged ~ 540 Hp with the same turbine housing which is not really the gun thing though availabvle housings are an issue - ATM . Cheers A .

Wasn't going to get involved in this one but here goes . For a start please delete all notions of "negative pressure" and pistons or engines "sucking" . Firstly negative pressure doesn't exist - its as simple as that . You have a total vacuum or zero and everything above that is positive pressure . We have been brought up with this brain dead notion that atmospheric pressure at sea level is zero and anything less - is negative ? The technical terms are PSI"A" meaning referenced from absolute zero and PSI'G" meaning PSI Gauge pressure referenced from sea level atmospheric ie ~ 14.7 PSI/1000 millibars . Your Skylines manifold gauge is whats called a compound guage because it measures either side of 1 BAR or 1 barometric which is 1 atmosphere at sea level . If you look at turbocharger compressor maps you'll generally see a reference on the left hand side of the map and the units used are pressure ratio (PR) . This is because 1 PR = 1 atmosphere = 1 BAR = 14.7 lbs/square inch = 1000 milibars . The map really only tells us anything useful once the turbo can generate pressure greater than atmospheric and thats why the scale starts at 1 PR . Start two . Engines can't "suck" . What they can do is generate an area of lower pressure than atmospheric so the atmospheric pressure being higher forces its way into the cylinders - minus any restrictions that hinder its progress . This is the reason why its so important to have low restriction filters and everything else between the atmosphere and the cylinders themselves . NA competition engines can have high volumetric efficiency built into them but it doesn't fit in with the noise/emissions/power characteristics in road car engines . Supercharged engines (forced induction) can easily get good cylinder filling because they have greater than atmospheric pressure at times in their inlet manifolds so the restrictions down stream of the compressor are less of a problem innitially anyway . The whole reason to supercharge a piston engine is to get higher torque that the same sized NA engine can develop . These days engines are far more complex than they used to be so turbocharging is not as simple as it once was . In my mind I think a better measure of forced induced vs NA performance is torque and all engines are different on that score . For example a 4.5L 4 cam Jap V8 may make better overall power than a Holden 5L iron nob but both will be way ahead of your RB25T at lowish revs . Turbo or mechanical supercharging is not a free ride and they create as many problems as they solve in high performance tune . One of the biggies is that once you get more air and fuel in to make higher cylinder pressures you get a higher volume of exhaust gas to have to deal with - bigger engine exhause flow . In some ways this is the most important aspect to deal with because even though the engine only operates in a supercharged state some of the time its exhaust tract has to cope with high mass flow all of the time . Its a big ask to drive a healthy sized turbine that won't create unacceptable restrictions and have the engine responsive as well .

I wasn't actually looking for this pick , it kind of found me ?

That would not be one you'd see very often , a port shrouded GT3582R . You see the odd one in the US but its not a version Garrett market out here too often - this asumes it has a T04S comp cover and not some other oddball thing . Cheers A .

Hi Cubes , it may be interesting to have a look at some of Garretts data on T3 flanges and port dimensions . You may find that the Nissan "T3" flanged exhaust manifold is actually split or twin entry T3 flange size . I think its logical that split T3 flange ports would be slightly wider because the divider takes up some space . Cheers A .

Port shrouded compressor housings do zip for you provided the compressor is operating outside its surge zone . The things that make these turbos surge are small A/R ratio turbine housings and large trim compressors . People have to understand that small exhaust housings help to get the turbine up to speed BUT if the compressor tries to pump more air than the engine can swallow you get pressure fluctations - surge . The propper way to do it IMO is to use less than the largest compressor trim option if you must use smallish exhaust housings . Big trim compressors create more turbine lag than medium or smaller trim wheels because they take more energy to drive . Specifically to HKS's GT3037's . The normal or "straight" GT3037 uses the std form 0.60 A/R TO4E compressor housing ie 2.75" inlet and 2" outlet . These are easiest to package because of the smaller inlet boss ie 2.75" vs 4" . As I said if you don't need the port shrouded comp housing this is the way to have it . The port shroud actually costs a little bit of compressor efficiency (and screams its head off) but thats preferable to surge . The GT3037 "S" variant are the ones with the ported inlet shroud and HKS intended them to have large A/R exhaust housings ie 1.01 for the 52T version and 1.12 for the 56T one . By the way I believe most of HKS's turbine or exhaust housings were a hybrid GT30 housing with the T28 mounting flange . Your call but I would never use that flange size on an RB 6 cylinder . I don't think its possible to merge 6 exhaust manifold runners into a flange of that size and not get an unacceptable exhaust pressure rise . The RB26 is different because it has two turbos meaning only three manifold runners and three cylinders to handle . Nissan went with the divided T3 flange on single turbo RB's almost certainly for this reason . The easiest GT3037 you'll ever fit to a single turbo RB is the Pro S Version , the reason being that HKS has a model specific one that goes on the std exhaust manifold and includes ALL the plumbing and a dedicated dump pipe . Expensive yes but when you add up all the fiddlies needed and the running round to find them its probably not so different . Cheers .

Nope , the GT3037 series turbos used 3 different trim versions of the 76.2mm GT37 BCI-18C series comp family . The inducer sizes are ~ 2mm different ie 56T = 57mm , 52T = 55mm , 48T = 52.8mm . From their compressor maps the choke flow in corrected Lbs/min for the 56 and 52T versions is ~ 53 and 50 lbs/min . Cheers A .

Not sure , I'll ask later in the day or this evening . I have a feeling that international parts junket Seema Ceema what ever is looming so time may be short . If I had the time I'd search through some of the Supra or Bimma forums to see what sorts of results they are getting from 2.5-3L turbo twin cam sixes . Some of the Supra crowd are pretty switched on but like everywhere some want too big too much too sick . If I hear anything I'll pass it along , cheers A .