discopotato03

G'day Cubes , some Garrett contacts in Torrance Calif are trying to push the GT40R turbo for the 26/31 hybrid . They reckon full boost from 4000 but its getting seriously big . I'm getting them to chase up details of available turbine housings but LOL probably a bigger mouthful than I can chew on ! I do know of someone over here with a custom "GT3542R" hybrid that reckons it spools fine . Its using the 102mm GT42 compressor , big enough to hide under . I've gotta get back to SK to see if more than 9:1 CR is of any benefit ie 9.2 ? Cheers Adrian .

I think you'll find the Pro S versions of both the 2835 and 3037 are the only ones with integral wastegate and T3 mount flange . These turbine housings are HKS specials but can be bought separately . These housings have the "GT Pro" outlet whatever that is and may have HKS specific dump pipes . Cheers Adrian .

Cubes I will probably go with the 1.06 ARR GT3540R just not sure about which comp cover . My engine will have 9 to 1 CR via the JE VG30 Piston solution , expensive but worth it . Wont be built in the near future , so far have 33 26 top end and pistons so still gathering bits as funds allow . Chow Adrian .

Nismoid , is your "GT30" using the GT37 or GT40 compressor . Both are six bladed , the 37 is a 76mm wheel in a T04E cover while the 40 is 82mm usually in a T04S cover . The GT30R (76mm compressor) is normally rated at 500 hp .

I can only repeat what I was told by someone who's been there . SK said that the RB25 or 26/31's make that much exhaust flow that they'll spool nearly anything . He said that ideally you want the turbo to spool up at approx 32-3300 revs otherwise it tries to spool up at the gearchange point and drinks copious amounts of fuel . I imagine that twin cam RB30's are not lacking torque off boost as long as the compression ratio is adequate . This is where you need to understand the static and dynamic compression ratio part . Static comp is worked out assuming no inlet restriction . Dynamic comp ratio takes into account the partly or nearly closed throttle plate/s . Obviously you can't have nearly as good cylinder filling with a closed throttle as an open one . The more air you can get into the cylinder the more there is to compress for high cylinder pressures post combustion . Higher static CR means all else being equal higher dynamic compression ie same volume of gas squeesed into smaller space = higher compression pressure . Where this takes us to in the real world is more part throttle low rev torque to drive us down the road . This extra torque is not gained from boost so we get to start the onset of positive pressure higher up the rev range . We have the opportunity here to use larger turbines / housings to offset the restriction at the other end of the rev range and retain a little more volumetric efficiency . Part throttle driving off boost give us the ability to get good fuel mileage at 110 on the expressways . I don't like the GT3040R personally (based on theory not practise) , and in the RB25 - 26/31 case we are not short of exhaust flow or part throttle torque so the bigger turbined GT3540R should pay off handsomely . My vote goes to the GT3540R . Cheers Adrian .

As engine torque increased with capacity (and forced induction) the shafts and gears get heavier to cope with the increased loads . In some cases double and triple cone syncros have be used to reliably slow down or speed up the mainshaft gears to allow smooth quiet engagement . Trouble is the syncroniser assembly gets bigger and heavier creating more fly wheel effect making the syncros work harder and wear out faster . In a perfect world the shafts/gears/syncro hubs/ clutch plate would weigh nothing and changing gears would be easy all the time . Because they aren't and we use big revs and wide ratio (production gearboxes) the syncros get a hard life . They are not designed to be taken to the rev limit in 1st and bashed into 2nd etc . Road cars are designed to have a broad spread of torque starting at lowish revs and with 3000 rpm , change , driving they work fine . We've all been in that situation of putting along at low revs in high gear and desire acceleration . So we go back two gears asking the syncros to accelerate the layshaft and 1st motion shaft/ clutch plate up to the speed of the lower ratio for the same road speed . Cone clutches in gear oil only work so well so if we beat the bault ring and force the coupling sleeve ito the gear at big speed differences it going to go crunch . Double de clutching brings the engine and gear train up to speed , reducing the work and load on the cone clutch AND has the engine in the right speed range to accelerate the vehicle . Often double de clutching can speed up a gear change when the ratio spread is wide . My experience is that syncro boxes hate clutchless changes so I don't do it , its probably to do with the fine dogs on the gear/coupling sleeve . Dog boxes have big gaps in the dogs so handle it much better . With a bit of practise they are lightening quick to up change , gentle pressure on the stick and slight lift off on accelerator to unload the coupling sleve and snick . One thing you will notice with them is the bang and clang , they are noisy and have a fair bit of backlash which people would never put up with in road cars if if Joe average could change the gears . Close ratio boxes help as the speed difference between the gears is less . Some company's in the US do half dog boxes ie 1st - 2nd dog change and the rest syncro . I've never driven a production six speed car box such as S15 , R34 or the B Double box that the Vomit Doors get's . Are the Nissan ones fairly close ratio and do they change well with a boot full of revs . The above epic is my interpretation but feel free to comment , the discussions on this site are really good . Cheers A .

Lots of personal opinions here so I'll add my own . I believe the earliest multi ratio gearboxes had gears that moved sideways on the mainshaft to engage with those on the layshaft or the back of the ist motion shaft (input shaft) for top gear . Engines of the day had a very narrow rev range compared to todays designs and road speed was slow . Generally these gearboxes had large gears and shafts with lots of innertia or flywheel effect . To change down we had to dip the clutch change to neutral , off the clutch and rev the engine to bring the geartrain up to the sort of speeds where the desired mainshaft gear could slide into mesh with its matching layshaft gear . Off the clutch and maybe we could coax our Model T Ford up that savage 1 in 100 grade . Later designed gearboxes had the mainshaft gears running on bearings so that all the mainshaft/layshaft gear pairs could be in mesh but none of the mainshaft gears locked to the mainshaft . The mainshaft also had coupling sleeves with dove tail shaped dogs on the side that could move sideways to engage the dogs on the sides of the mainshaft gears to lock them and allow drive . These are called constant mesh dog boxes and still exist today in trucks and competition car gearboxes . The coupling sleeves eventually grew baulk rings and cone clutches and are known as syncro boxes . To be continued , out of time .

Hmmm , may need to revise the wish list from 3100 GTST to GTS4 . Did these come in an auto ? Bummer there's that PFC / auto prob again . Won't be taking on any wagons till I've got the Audi RS6 which means not is this life time ! Cheers guy's A .

That RX7 hybrid used a six blade wheel so wouldn't be a V trim which has eight . The -14 or 2nd last 6 blade shown is very close dimensionally to a V trim . The E wheels have two distinct blade forms , earlier types are layed back from the wheel hub sort of cropped . The later type have a large spot face for the lock nut to bear on and the blades are not level with each other ie 180 deg appart looking into the inducer side . Safe bet Bill used -14 T04B , cheap easy to get and minimul machine work . T04B's are a flat backed wheel where T04E's are a shallow tulip shape , deeper through in section needing a longer turbine shaft . That article mentioned a map very similar to the -14 / -15 maps ie long and low to the right meaning wide range at relativly low pressure ratios - just the thing for OEM power output for the era .

If you look closely at the first one it had Warner/IHI on the compressor cover . Probably safe to say its an IHI , they do turbos for Evolution Lancers some Subarus and lots of others .

Camereon-Datto , I spoke to him at the time and not surprisingly he wouldn't say . The article said it used a T04E wheel which was a crock a shite . Have you ever seen a 70mm eight bladed E wheel ? no one else has either inc Garrett . The fellow I knew looked very closely at the compresor cover inlet (picture), measured up the snout of one he had and opted for the -24 T04B wheel . He was certain Bill used the slightly larger trim -25 T04B wheel . Quitly frankly it wouldn't matter which eight blade B wheel was used , they're all useless for petrol engines . The problem is they were designed to move lots of air (for their size) at low to medium shaft speeds hence lots of blades . The newbies try to use them with turbines designed to drive six bladed wheels at higher speeds . Innitially this causes lag and when it finally gets going it pumps too much air for medium engine speeds and starts to surge . To have any hope of working this needed one of the six bladed 70mm T04B wheels of which the H trim was one , but there was also one of similar size to the V trim ................... Just dug out the old paper work : T04B 8 Blade wheels commonly used . 409179-0021 70x48.36 = 48 trim . Known as S trim 409179-0022 70x49.50 = 50 trim 409179-0023 70x51.61 409179-0024 70x54.00 409179-0025 70x55.37 = 63 trim . Known as V trim Note the dash 24 and 25 , the last two above . T04B 6 Blade wheels 409826-0006 70x48.35 = 48 trim 409826-0012 70x52.85 = 57 trim 409826-0014 70x55.30 = 62 trim 409826-0015 70x58.40 = 70 trim . Known as H trim . I only know of the last two , dash 14 and 15 being used in place of the 8 blade variety . I did hear Turbo Dynamics in Sydney liked the six blade versions in their hybrids . I vaguely remember someone in Zoom or HPI did an article on replacing the twin turbos on the series 6 RX7 with a single to get around reliability probs with the twins . It involved fitting basically a turbo/manifold off a series 4 or 5 RX7 and the , drum roll ....... "Trade Secret" we won't tell you compressor wheel , looked very like one of the six bladed T04B's .

Those things are a wally turbo . Garrett NEVER offered anything like that in the TA34 range . T3/T04E is a generic Wollynetics term only . Garretts TA34's used T04E compressor wheels up to about 46-50 trim . They knew that the turbines could not adequatly drive larger trim compressors . There was also a wide range of turbo's in the TB31 series that used these turbines with garden variety T3 compressor wheels . If you buy one of those things you will go faster , but only due to the wallets weight loss factor ...............

Its a T04B probably .60 ARR compressor cover . Way way too small for a GT40 compressor wheel . I'd like to see the "Cosworth .63 AR "Turbine housing . If its off the TA34 (wrongly called T3/T04E hybrid , a phrase coined by turbonetics) fitted std to the RS500 sierra , it can't work properly . The TA34 turbines had much less tip height than GT BB anything . If it was re-profiled (the turbine housing ) it is now junk . Why anyone would want to use these housings on a GT3040R CHRA is beyond me . Firstly the GT3040R is not an ideal match . Secondly the GARRETT integral gate exhaust housing kills the efficiency of the UHP GT30 turbine , leading to excessive turbine inlet or back pressure . Thirdly the T04B compressor cover kills the efficiency and chokes to death the GT40 compressor . You must remember that Area to Radius Ratios (ARR's) for turbine and compressor housings is worked out based on the original (native) wheels diameter . GT40 compressor wheels (82 or 88mm) generally use T04S comp covers which are huge compared to T04B's . The individual who built that turbo has little idea or respect for how turbochargers work . Smaller GT30R's with the correct housings could make more power and have far better transient response than that thing . Also note that the RS500 Sierras were a dog on the road and track , they had all or nothing power delivery and plenty of cheat components . For starters the turbine housings were extrude honed which enlarged the volute and ARR ratio . There were some illegal (larger) turbine housings as well . In a vain effort to chase RB26DETT power they were allowed external gates to control boost . No way the integral could bypass enough gass to allow 500hp from 2L (122 Cu in .) . Do not attempt to emulate this turbo as a well set up GT30R is better all round . The TA34's were the end of the road for bush bearing turbos , the GT's eat them .

Ah yes ATS .......... They built that bastard hybrid for that wacko importer over there that can't keep his tongue in his head . For that "drift unregistered RB20DET One Eight Via ? " It used the turbine from a series V RX7 and a -24 or 25 T04B compressor in bored out (bastardised) RB25DET Hitachi housings , actually the turbine housing was VG30 . Someone I know coppied it and it was a surging pig . On ya Bill .

I always wanted to see a GCG Highflow from the compressor and turbine perspective . I don't suppose you could let me see (please please please) some pictures of it with the covers off . I suspect it uses a 76 trim TA34 turbine , and that compressor just could be what Garrett (Chipping Norton) called the "T3 highflow Wheel" . It was standard on the Buick Grand National and off the top of my head the part no was 299-4 . I once had the map for it so have to have a look . I'm thinking XTR turbos are rebuildable using Garrett plain bearing style turbines and compressors so not necessarily getting the latest aero technology with them . At least they fit straight in ......................

You could measure the exit side of the exhaust housing , if its about 55mm its a GT30 turbine making the turbo a GT3040R . If its larger (cant remember exducer size on a GT35 turbine) its probably a GT3540R . Compressor covers are not a sure fire way of identifying turbochargers . GT37 compressors (GT30R) generally use T04E covers , while GT40 compressors can use T04E or T04S covers . Turbine size will tell for sure . Cheers A .

Fellas I've not tried these on RB's or anything for that matter . From a technical viewpoint the combination of a 60.1mm turbine and an 82mm compressor is not ideal . Thats not to say it wont work at all but , Garretts production engineers believe that the turbine cannot develop adequate shaft power to efficiently drive a compressor of that size and capacity . Even if it could the sort of airflow that a GT40 compressor can develop would be let down by the shortage of exhaust flow capacity of the GT30 turbine/housing . American Honda tuning firms spend their lives doing back to back tests with GT30R's , GT3040R's and GT3540R's and the results are always the same . The 3040R can develop higher power levels than the GT30R but high turbine inlet pressure (back pressure) becomes the limitation . The GT3540R has the same compressor/cover as the GT3040R but its turbine in 8mm larger in diameter or a smidge over 1.25 times its cross sectional area . So in effect the levers driving the shaft and compressor are longer (more mechanical advantage to develop shaft torque) and the path for exhaust gasses is less restrictive . The GT3540R will nearly always be capable of higher power outputs than the GT3040R because it can get lots of air in and lets lots of exhaust out - in balenced proportions . They can be hamstrung with too small an exhaust housing in an effort to spool it on an engine really too small for them , but the result is nearly always compressor surge . You won't be the first or last to try bridging the gap between the GT30R and GT3540R . To a degree it can be done , this is why different sized (ARR) turbine and compressor housings are made . If response is important then larger housings on the GT30R can extend it beyond the norm . Alternatively the mid size turbine housing and one of the mid or smaller T04E comp covers could wake up the larger GT3540R . Its always going to be a compromise .

Garret sells the turbo minus the turbine housing ie centre housing rotating assembly (CHRA) with compressor cover and backplate . Its part no is 700382-12 . There are three available non gated turbine housings ie .63 , .82 and 1.06 AR ratios . Housing part nos are 740902-2 (.82) and 740902-1 (1.06) , not sure about the .63 version . Alternatively HKS do a .68 and a .87 AR integral gate housing also in T3 flange . GCG can get them but not cheap at $800 ea . I believe these two are aimed at RB20's and RB25's with HKS's GT3037 which uses the same identical CHRA as the GT30R . In fact the ONLY difference between the GT30R / HKS GT3037S is a slightly different version of the port shrouded compressor cover (bell mouthed) . I was recently acused of pushing GCG's name so if anyone asks no I don't work for them or anyone remotely involved in the automotive industry . Hope this helps , cheers A .

HypeR33 count the number of blades looking into the compressor housing . If it has 6 full height and six half height it will be a BCI 18C series GT wheel . If it has 7 full and 7 half height it is a T04S wheel . The rule of thumb with compressors is the lower the number of blades and the thinner the blades , the more efficient an air pump it is . The BCI 18C range of compressors are designed to be a high speed wheel ie the angle of attack of the blades is shallower that the T04S . They (BCI 18C) have less innitial bite into the air so that all available energy (shaft power) from the turbine is available to spin it up and generate airflow (boost) . They have an extended rev range compared to earlier designs , and this is why they pump as much or more air than earlier designs while being smaller and lighter . Being mechanically strong (more able to withstand the centrifugal forces of high rpm) allows the compressor to be compact , and light weight (less mass to accelerate) so helps reduce the innertial lag component of getting to boost rpms . When Garrett developed the GT or Garrett Technology series , most of the effort innitially went into the turbines because this part had the greatest potential for improvement . Because bush bearings (and plate type thrust bearings) limit the rpm of the shaft , high speed wheels were not designed in the past because the bearing system could not reliably survive higher rpm's . The GT turbine and matching turbine housing is a set and should not be fiddled with apart from ARR changes . These turbines are much much lighter than the dinosaurs they replaced . They have a more paddle bladed appearance or greater tip height . The nozzle or channel in the turbine housing is wider and allows greater mass flow across the blade inducer tips than earlier designs . GT turbines and matching housings have quite high specific flow ratings for their physical size , they can easily out flow T4 turbines and housings while being lighter and more compact . Like the compressors they are also much better able to stand higher cetrifugal forces . So Garrett produced these wonderful turbines and hung old school compressors on them while compressor development went on . They had oodles of the old types and the market bought them like hot cakes . There's and old marketing saying , if it sells why change it . They still sell and people still buy them , generally the sharks sell them a little cheaper and still call them a GT30R - but its not the real one . Ball Bearings yes , modern efficient compressor no . Dont forget an inefficient compressor drags turbine efficiency down with it . Add some bastardised modified non GT type turbine housing and you've built a real dog . For your own sake do it once do it right - even if the right one costs a little more . Trust me its cheaper in the long run .

HyperR33 the specs they gave you are for a GT3040R . The GT30R (700382-12) uses a 56 trim GT37 compressor in a port shrouded .60 ARR T04E comp cover . Garrett really should call them GT3037R for their GT30 turbine and GT37 compressor . Don't let anyone talk you into buying one with a seven bladed T04S compressor as it is not a propper high rpm GT wheel .

I guess any car can oversteer if the suspension is set up for it . I'm told the R32's front suspension can do things that S13/14/15's can't , but thats about making rapid forward progress - and pointing in the right direction .

Have any of the S13's been much of a success in road racing anywhere ?

The Pitstop Bookshop - www.pitstop.net.au in Perth . Very very good mail order service , huge range . Also bagged a copy of Bathurst 1992 highlights , a must for any R32/GTR fan .

I know you can buy the S15 BB CHRA , maybe not through Nissan but Garrett dealers can get them . One I know has tons of second hand stuff so he could cobble one together .

LOL it was a DR30 and in car film . Its on the video "The Great race , the Turbolent years Bathurst 1986 - 1992" . Great driving for basically an overgrown Datsun 1600 with a top endy FJ20ET . It was interesting to watch the R31's race , they appeared to be driven on the rev limit everywhere .