discopotato03

One of my mentors speciality was rallying early Datsuns . There came a time when turbocharging was the thing to boost the performance of Rally and Circuit race cars - call it the Group A era . Traction was always the issue on the dirt and AWD was the answer for this . Manufacturers did all things fair and foul so the regulators had to find a way to level the performance playing field . Inlet air restrictors was their solution . Simple and effective - you can have as much air as this gadget can flow and no more . So , the first thing they found was that conventional performance turbos didn't work . They'd get to the flow limit of the restrictor and fall flat on their face . So the next step was to downsize their turbos so that most of its effective range fell within the flow limits of the restrictor . Some of you may remember that the TME spec Evo 6 4G63s had a TD05 turbo with a smaller compressor than the std or GSR spec Evo 6 . They came on boost earlier and made rated boost (from memory) at something like 2800-3000 revs . We can do a lot of guessing about choke flows , my theory go like this Just about everything on planet earth air wise is pressurised by our basic 1 Bar at sea level . 1 Bar being approx 14.7 Psi/100kpa/1000Mb . Many people have a hard time believing that their is no such thing as "suck" , death and tax man aside . When an engine draws air in it's actually being pushed in by atmospheric pressure . The roads to high airflow with only 1 bar pushing is a lot of area . With turbos again you won't get any more air in than the atmosphere can push through a given orifice . When the compressor flow starts to out run the restrictor the pressure starts to drop ahead of it to the point where its so low that the atmosphere can't push any more in - it literally chokes . So you are left with a situation where you have to make best use of the air volume available and have the engine in a state of tune to work effectively with this flow ceiling . What the Rally teams ended up with was something more like a petrol fired diesel performance wise . Lots of torque at low to medium revs and forget about much over 5000 . If you look at pics of Grp A rally turbos they're nothing like anything else . Compressors look smallish with small trims in materials like magnesium . Turbines are made of very high temp spec alloys and possibly a little larger in diameter with medium trim sizes . As I said initially they gave up on twin scroll for the reasons Geoff mentioned and had ALS to virtually have them up to speed from a high idle . With Garrett I can't say but I know Mitsubishi put a lot of effort into Grp A homologation special turbos and these turned up on production cars . Evos 1 and 2 used a TD05H 16G - I think the "small" 16G 60 odd mm compressor . Evo 3 got the same TD05L turbine but with a unique compressor wheel of similar dimensions to the "big" 68mm 16G diesel wheel . Everyone calls this Evo 3 16G compressor , the difference aside from aero geewizzadry was that the wheels hub and front boss were reduced in area and mass so less weight and more blade area for a given inducer/exducer size . As we know Evos 4-9 went twin scroll and reverse rotation possibly with the same wheels aero . Twin scroll gave them the ability to wake up quickly and interestingly Mitsy turbine housing sizes increased from around 9cm to 9.8 and 10.5cm from Evo 6 . There were a few TD05Hr variations in the Evo 6 era - aimed at spinning up earlier and being able to cope with the restrictor in Rally trim . The TMEs turbine was TiAL to make it lighter and the compressor was reduced in size to make it live within a lower total air flow rate . Beyond Grp A but there were also a couple of special TD05s for the Evo 9 RS . They were a limited option of the TiAL turbine but with a light weight magnesium compressor wheel as well . There was two versions of these , first the flat back compressor which cracked and second the tulip backed one that didn't . I have one of those buried somewhere . Also a third version that had the reduced sized compressor wheel . Interestingly all Evo 9 turbos have the larger compressor housing with I think increased diffuser diameter . Any way , If it were me trying to spec a turbo with a restrictor I'd be finding out the restrictors max flow and working the compressor and housing numbers around that and the engines capacity . If anything I'd start with smallish compressors in relation to turbine size which is basically how early generation diesel turbos are . My 5c spent .

One thing I can add is that I'd say what you mean by GT"29"71R is that it probably has that ancient cropped GT30 turbine in it . If so these were a GT30 UHP turbine that had the blades shortened - trying to fudge a turbine size in between GT28 and GT30 . The idea was to make effectively a smaller more responsive turbine than a GT30 . It doesn't work because having the GT30 sized turbine hub with shorter blades isn't the same as having a purpose designed turbine with the same inducer and exducer diametres . Long story short these GT29 turbines were never efficient in any turbo . Too much hub mass and volume for too little blade area . I think as mentioned the G25 should be a step in the right direction . Something else to think about is the turbo tech used in the Group A rally days of inlet restrictors . A huge amount of research went into their turbos and they were very different to virtually everything else . From what I remember they were trying to get the things to come on as early as possible and make ginormous torque over a reasonably narrow rev range . The numbers were something like 650 Nm of torque from 2000cc and it was all over at 53-5500 revs . I think early on manufacturers started doing the twin scroll thing ie some EJ20s and most 4G63Ts but in the end it was simpler to use anti lag systems with more conventional style open manifolds and turbine housings .

Short of time at the moment but . Recently I noticed that Mitsubishi released a turbine called (from memory) TF06 - which is sort of similar dimensions to a GT30 turbine . The turbo is called TF06-18K and similar wheel wise to a GT3076R . They have the most modern Mitsy wheel designs AFAIK .

I'd certainly like to know more about tuning with an EMAP input .

I forgot to add that SSS 200Bs had drive shafts with hooks type uni inner joints I think similar to a K or Z . Pretty sure 910SSS had pod and CV joints , and an R180 diff . Probably similar to Aus spec MR30 2.4E . DR30 of course had the larger R200 and shafts and larger solid rear brakes . Their R200 LSD has less plates than the Nismo and a spacer . To make better simply remove the spacer and fit a full set of plates .

No they don't . The cross member mounts aren't there and neither is the rear R series diff mount . The closest thing you can get is the 200B SSS rear end . To fit this system up to an Australian 910 you have to open up the tops of the rails . From underneath the box sections the outer skin has the relevant holes but the inner doesn't . I chopped the rear pin mounts out of some early type Skyline at a wrecker . Arthur Jackson machined them to sit in the opened box section and welded strengthening webs inside the rails . The X member mounting studs were I think 1600 type with the tapered shank . JDM 910s and R30s have the studs welded into the rails . JDM 910s have a different body cross brace to ours and the R series diff is suspended from a single horizontal bolt . Mine used a moustache bar that Stuart Wilkins used to make and had vertical bolts that went through strengthened sections of the boot floor - from memory . I think that bar is still here with urethane bushes . The 910 or 200b SSS rear setup would be lighter and the struts would line up better . Funnily enough Australian shells have the mount for the IRS type hand brake cable clevis . Back in the day I tried to sell my IRS FJT'd Bluebird fully engineered for $7000 , no takers . Everyone though they could do it cheaper . I sold most of the bits out of it and the last time I saw that shell it was on the back of a truck with the crane boom through the roof .

Yep , airflow through a 910s engine bay isn't brilliant . Factory standard with the carburetted L20B they used elec fuel pumps to get around fuel boiling in the carbs and hard pipes . I think the issue is convincing warm/hot air to flow down around the gearbox and out underneath . The two factory cars with FJTs from memory were R30 Skylines and some S12s , both of them had fairly long engine bays particularly R30s . The FJ looked weird in my DR30 - being so far forward . You probably don't want to hear this but the two biggest issues with 910s are cooling and rear suspension woes . I solved most of the cooling ones but with a lot less power than you have . The std 4 link rear is pretty hopeless , with any body roll the diagonal top links pull the inside wheel forward and makes it try to rear steer . This would have been part of the reason why S1 Bluebirds had such soft sloppy rear suspension bushes , the S3s were better . Mine was aggravated by the Detroit locker I ran because I couldn't afford a Nizmo H190 clutch LSD . Highly amusing in a straight line . I remember out running some clown in a 351 XB up the old Woronora bends west of Sutherland one afternoon . Detroits are great if all you want is grip but they will crack/tear the rear suspension body mounts of cars like Bluebirds . It's also funny taking off from the lights with D lockers if both sides aren't locked . First all the drive comes through the locked side then the other side lines up and engages with a crash that makes you think you've broken an axle . My first attempted fix was a one off 5 link Panhard system , it didnt rear steer as much but to get it to work properly would mean raising the top links and housing them in "boxes" where the rear seat pan is . Some classes of rally BDA Escorts allowed this and it works well from a grip point of view - hardly practical in a road registered car . I knew of one Rally Stanza this was done to and it worked too well , as in the rear didn't want to unstick which doesn't work on the dirt .My second try was to graft in the whole DR30 R200 semi trailing arm IRS setup . Again better but heavier as well . I look at Datsuns semi trailing arm system as half way between live axle and proper multi link IRS . Its issue is that you get significant toe and camber changes as the suspension rises and falls . It was more comfortable - and who doesn't like the R200 diffs shafts and brakes after Astrayan content garbage . Anyway Nissan solved many of these issues with S13s and later . I'd had enough of 80s issues , with the DR30 it was horrible drag link steering and no spares for steering boxes . I bypassed the S series and went with a GTS25T .

I still have my R33 , it sees the light of day about twice a year .

This takes me back . I mucked around with S1 Bluebirds through the 1990s and I also went down the FJ20ET road . Mine was basically a DR30RSX in a 910 shell , it had the DR30 R200 rear end grafted in as well . Cooling is a pain with them . I used an R32 GTR radiator and a very early Plazmaman intercooler . Arthur Jackson went to a lot of trouble to basically reconstruct the radiator support panel to fit that intercooler . It needed the OE Bluebirds bonnet catch section removed and a Datsun 1600 dog cock style catch system fitted . You have to cut a section out of the underneath of the bonnet and weld a piece in to take it . All worked really well . A bit OT but the best master cylinder system I found was to get a 910SSS booster and get it opened up and re orient the outer half 180 deg from std . That way you can fit a JDM Nabco or Tokiko master , I think they were 1 inch . The Australian booster is garbage and the PBR/Girlock 13/16 master worse . I think I had the external proportioning valve but eventually went to a Rally style adjustable one . Most of the OE stuff is probably unobtaneum nowdays , I was lucky enough to rape front cuts for the small stuff after others had bought the Z18 and box .

I agree , law of diminishing returns . Thanks for your G30-660 results , it'd be the one I'd use from the G series range .

Your calls but I think the filter bypass valve is there for two reasons . Firstly some careless or clueless never change oil and filters . Secondly really cold climates may make it hard for oil to flow through the filter . When I was playing with L20B fours back in the late 80s I had that bypass removed and plugged , I was using a remote filter as well . Note that L20Bs use a larger Z115 style filter std . I don't think oil filters magically clog up , if you are prepared to change your oil and filter at reasonably regular intervals you should never have a problem that a filter bypass could solve .

Just thought I'd check in with something that you may not have seen . GCG Turbos is advertising a G25-550 with a T3 flanged integral waste gate turbine housing in 0.73 AR for Nissan Patrol diesels - I think the TD42 engine . I think there is also a 0.64 AR turbine housing version . https://gcg.com.au/turbo-charger-garrett-g25-550-0.73a%2Fr-iwg-std-t3-nissan-patrol-td42-outlet-g871389-td42-73.html?ref_cat_id=Performance-Turbochargers-Garrett-G-Series With what Geoff just mentioned the 0.73 AR could be ok with that turbine if you wanted the typical 300ish Kw at the wheels in an R33/34 GTST/GTt . The G25-660 may be more suitable depending on power goals .

Many years ago I had an FJ in a Ser 1 TRX . Was a major operation to reconstruct the rad support panel . I used an R32 GTR radiator with DR30 fans and an early Plazma intercooler . Arthur Jackson did the fab work inc the cut and welded bonnet to take a 1600 dog cock style bonnet lock . Turbo wise a GT3040R or as some say GT3082R is definitely old school . The HKS version worked better than the Garrett marketed one , the difference was the 50 trim compressor in the HKS compared to the 56 trim one in the Garrett marketed version .

Bluebirds always had issues with hot engine bays , the std L20B needed an elec fuel pump to circulate enough to stop fuel boiling issues . They don't appear to have good airflow through the engine bay meaning down past the transmission and out underneath . The FJ20ET takes up a lot more space than the L Series and this doesn't help .

With the numbers Hypergear is getting from Neo 25 original inlet manifolds I wouldn't go aftermarket .

Yes very interesting , I'd like to see them on the G25 and G30 .

Going back to the OPs thoughts , T3 Open vs T4 Divided - and why you don't see many divided T3 systems . Firstly need to go back to when these flange sizes (footprints) were first made and why . T4 started out as a truck diesel thing from memory back in the 1960s , open and divided . Garrett was producing turbos in different locations around the world and there a a few variations of what people like to call T4 . To keep it simple I'll say the big size is T4 , and what people like to call divided T3 was actually "T4 International" . These may have the same external dimensions and stud pattern as the generic T3s but the total distance across the divided ports is approx 10mm wider than the T3s single port . Anyone that bolted say a GT30 on an RB25 would have noticed that the turbine housing inlet isn't as wide as the exhaust manifold ports and it forms a step in the wrong direction . Truthfully the only thing T3 about an OE 20/25 turbo is that stud pattern and external flange dimensions . Garrett T3s I think came about in the early 1970s , I believe it was because T4 was really too big and heavy externally for passenger cars especially turbines and their housings . I think N trim was the smallest of the original "T4" turbines and these are not exactly small light or responsive for smallish passenger car petrol engines . Anyway the T3 centre housing was the same as T4 as was the turbine shaft diameter , but the turbine wheels were smaller and lighter and the compressor wheels and their housings and backplates . T3 compressor wheels where also a more modern design than the agricultural T04B ones so basically the T3 was smaller lighter cheaper and more responsive than most T04B units . Turbocharged production cars really took off in the early 1980s mainly from Japan and Europe . This is where your Nissan Z18s FJ20s 280ZX and eventually RB30ETs actually used small series T3 cartridges in Nissan supplied turbine housings , note these were the small T3 turbine series units not the larger T3 turbine series cores found in say Buick grand Nationals . These turbos and engines were not brilliant by todays standards but they opened eyes back in the day when the usual roads to decent power was more cubic inches . Now to twin scroll systems . These were originally developed for big truck diesels to give them more torque at low revs and wider power range . It was a lot easier to do this with a diesel because you could size the turbine/housing to suit the engines power and power range without a wastegate . With a petrol engine in a road car the turbo needs to be sized so that it wakes up reasonably early and doesn't over boost or over speed in the upper half of the engines rev range , hence he waste gate . Also because mechanical/thermal/detonation limitations cars back in the day road cars didn't run very high boost pressures and generally had lowish compression ratios . As for the split pulsed manifolds and divided turbine housings go I think the gains are mainly from making our humble piston pump work better , or maybe I should lose less for having restrictions in the exhaust paths . Many of you won't remember the days when general purpose cars had pretty woeful OE exhaust manifolds , literally a hole for each exhaust port on one side and one out the bottom for a single engine pipe . Higher performance designs were basically split pulsed ones with two outlets to try and get some scavenging happening so hot spent exhaust gas didn't reverse back into the cylinders before the exhaust valves closed . It's not a very difficult concept to understand . Its obvious that gas under pressure will always travel towards the least path of resistance . so you have your power stroke and towards the bottom of the piston travel the exhaust valves begin to open . The combustion temp drove the cylinder pressure up so when the exhaust valves open there is a path to lower pressure beyond so out the exhaust gas flows . The theory is that when the cylinder blows down the velocity of the gas can actually leave a lower pressure in the exhausting cylinder than than down the exhaust tract . If there is a sufficient pressure rise in the exhaust tract then some of the exhaust gas WILL change direction and flow back into the cylinder - this is known as reversion . When you have pulse divided manifolds and divided turbine housings each half of that turbine housing is only seeing half as many exhaust pulses - so the time between pulses is double of what a single scroll system see's . That extra time before the next cylinder blows down gives the present one a better chance t get most of the hot stuff out before the exhaust valves fully close and seal . Now from the turbo/turbines perspective . To make lots of power (torque) you have to be able to move a lot of exhaust gas or the engine will choke (massive reversion) . So luckily for our twin scroll system we need to have reasonably larger turbine housing volutes because our exhaust pulses like to expand into a reasonable volume and vent allowing the pressure to drop ahead of the next pulse . I reckon it's the opposite for the T housing and turbine . I believe the turbine needs short high pressure/flow spikes to accelerate it to the speed where the turbo starts to pump usefully . So I guess in a nut shell twin scrolling done properly means exhaust manifold pressure is low when it needs to be low (for the engine) and high when it needs to be high (across the turbine blades) . Single scroll means higher than optimal pressure across the exhaust ports and lower if more consistent across the single volutes nozzle and turbine blades . The down side of twin scroll systems is that they are a bit more complex and expensive to manufacture . The manifold has to group the exhaust ports in the correct order and is a bit more expensive to cast . Turbine housings are bastard to make because the divider at the nozzle cops a thermal thrashing and there isn't a lot of material in this area to conduct the heat away or just wear it . So expensive difficult to machine materials are needed to make them reliable . And then you need a control mechanism which is usually a wastegate . This is also difficult to arrange if the sides of the system are kept isolated . It's generally easier in a production car to make the wastegate integral which is what Mitsubishi did with their Evos 4-10 . Still not easy to make a shared or paired flat valve seal long term and their seats to not crack or warp. External gates are probably to expensive to use unless you are Porsche or some other very expensive low volume exotic brand . I should mention the parallel twins vs single twin scroll setup on things like RB26s here . Always remember that these were developed in the 1987-88 era with the technology and materials of 32 years ago . Two smallish twin turbos on short manifolds with separate waste gates for each bank of 3 cylinders , and fitted up close to the head so the body shell could drop over it on the production line . Maybe not ideal by todays standards but I can't imagine Nissan doing a twin scroll single with twin ext gates etc in such a low volume car . History has proved that GTR was a pretty successful concept and probably too good in some ways . Lastly T3 divided (really T4 International) vs T4 divided turbine housings . Imo the issue here is that it's a big ask to merge 6 exhaust manifold runners into the the two ports of the divided "T3" sized turbine housing . With the larger T4 divided size ports you are less likely to get a pressure rise ahead of the volutes and dual turbine nozzles . The whole idea is to keep the energy/velocity in the exhaust pulse as high as possible to give it the chance to vent its maximum into the turbine blades . This isn't as much of an issue when you have a single scroll turbine housing downstream of say an RB25s split exhaust manifold - particularly when its ceramic turbine is so so small as is its turbine nozzle . The thing no one eve talks about is that those RB20/25 turbine housings (as I mentioned earlier) are wider across their inlet ports that a real T3 housing is so would potentially have a bit less pressure rise at that point . My 2c spent , cheers DP03 .

The most involved part is making up a spacer plate if you want to use the R33's throttlebody and TPS on the Neo 25's manifold . I was given an R33 manifold top section so I cut its TB flange off and machined the rough side flat in a centre lathe .

Interesting . I am curious to know if the smallest , G30 660 , is anything like the GT3076Rs .

Geoff where do you think the G30s fit in compared to the older GT/GTX units .

I seem to remember there being a T25/28 flanged version of the integral wastegate G25turbine housing . I don't think the AR ratio was very high but I suppose if you want early turbine response it could be worth a look . Yep only 0.49 AR . https://www.atpturbo.com/mm5/merchant.mvc?Screen=PROD&Store_Code=tp&Product_Code=ATP-HSG-508&Category_Code=GTHG25

Congrats on having a go and it being a success . These are a few things to note if you ever decide to run the Neo inlet manifold and electrics . The idle air control valve housing is totally different and it's solenoid uses a different plug . Work around is to get one from early N14 Pulsars , or the NA Neos solenoid which use the R33 type loom plug . Other PITA is if you want to mount the R33's TB/TPS on the Neo turbos plenum - so you can fit up the R33s J pipe and plug in the native TPS . The Neo's bolt pattern is the same but the R33's mount flange is differently shaped so you can't just slap the 33's TB on the Neo plenum . To make it work simply make up a sandwich plate cut to the R33s shape . I was given an old 33 plenum so I cut the TB mount flange off and machined the back flat/square in a lathe . Thanks for the heads up on the crank pulley , I didn't know they were different . I don't have the finances to do a Neo motor yet but I will do the Neo inlet manifold in the not too distant future . Cheers A .

The actual solenoid is very similar to some Pulsar N14 GA16 ones . They had two styles , one type actually fits the R34GTt housing . The N14 one uses the same male connector as the R33 RB25DET's and is probably the one to use with Neo manifold/IAC in R33s . If you need to get the cold start side apart heat the housing/bung with a heat gun .

I've never had a problem doing them at 5 , I can afford it and it probably keeps things a bit cleaner internally .

Yes I've read about modern engines being supposedly so much cleaner too . The thing is that any garbage that gets past the air filter has to pass things like pistons and rings so if its crunchy it doing damage before it gets to the crank case and oil . I think the cleaner bit comes from running leaner air fuel ratios so less semi liquified carbon/soot etc going down past piston rings and into the oil . This would be a big issue for early diesel engines which were dirty things anyway . No doubt this led to having a full flow and a bypass oil filter . For those that don't know bypass filters are those with finer elements intended to have a low flow rate via a restrictor . They can't be used in a normal full flow application because they don't pass enough oil to lubricate the engine . This is a thread I looked at from the Nissan Patrol diesel crowd . https://www.patrol4x4.com/threads/baldwin-b50-bypass-filter-oil-flow.81757/ Note that their intention was to extend oil drain periods ie from 5 to 10,000 km , you'd think for cost and convenience reasons . Interesting read if you have a bit of time and nothing else to do . Something a bit more interesting is the "dual flow" filters which are supposed to act as a full flow and a bypass filter in one spin on cartridge . I think this is getting beyond what anyone here would need . Anyway , my belief is that a larger capacity filter has more filter area and I reckon less resistance to flow through it . At some stage I'll cut open and compare the elements of a 115 and a 145a . A .