discopotato03

Yes , there is less webbing on the early (red top) RB20 DET bellhousing so the later one is probably a little stronger . Internally I believe their the same , older , higher mileage . Cheers A .

Just to give some idea what I set out to achieve . The front struts I use were carried over from my last car (S1 Bluebird) and my No 1 priority was to get acceptable damping and spring rates . The man who developes most of my car mods has spent many years building and fabricating rally cars and their systems and is very switched on with suspension . As club rally cars evolved the need for good dampers and damping rates became mandatory . Getting springs of nearly any rate wound up is not difficult but controlling the energy absorbed by the spring is . The spring is really the shock absorber , but if the energy in the compressed spring is not controlled it tries to launch the vehicle off the ground ie no traction or directional stability . Back in the early 70's the works MK11 Escorts used Sport Bilstein dampers re valved to suit higher rate springs . The damping rates were about 290/90 and the gas pressurised oil resisted airation (air moves through the valve body with less resistance than oil - bad) . The struts used on RWD Nissan/Datsun cars generally take I think 30-32mm diametre inserts and are not available in the damping rates I wanted . Bilstein did do a rally rate insert for 1600's (510's) with larger strut tubes . Their rate was similar to the Escort version (cars of similar size and weight) . These are no longer available so the next closest thing was the Sport Bilstein that HDT used on the lower V8 Commode Doors , rate 274/70 something part no P36 0303 . They don't fit the std strut tube so they need to be extruded with a mandrell or the strut foot bored out and a larger tube welded in . So my dampers were designed for a heavier vehicle (cast iron V8 deluxo Barge Dunny Door) to suit its higher rate springs and heavier wheels/tyres . In the lighter Bluebird (and now DR30) it works quite well and the dampers are rebuildable . With regard to unsprung mass , the more weight you hang off the strut ie big brakes big boots , the more critical the damper rate becomes . Its more mass the spring has to throw when the spring extends . I'm not keen on Japanese aftermarket suspension , they always set cars up too low , spring rates too high and damping rates merely hard rather than controlled . What looks the part does not necessarily work real well . Silvias use a later development of the macpherson strut with the clamp type upright and a much shorter damper body/strut tube . Their geometry and strut to ball joint centres hub/wheel offsets are different to R30/910/R31 . Its a lot to hope that its all compatible let alone the spring/damping rate being suitable for your car .

Just to throw a spanner in the works - no . That car is hardly neat and on closer inspection would not be tidy . The boxy bits may cover silly sized wheels but did you note the front wheel offset ? , that thing would be bump steer city . There's no way you could get ANY reasonable amount of positive caster into it without the tyres eating the arches . The GRP A DR30's didn't look like that , and with the best of todays road tyres and suspension geometry findings you can do better . Ill take function over phat looks every time , function delivers lard does not .

Std R30 struts are coil overs . If by this you mean spherical top joints and threaded height adjusters you can build your own . 1) Take strut and remove spring seat , now grind the weld flush with the tube . 2) Cut the threaded section off the top of the strut tube . 3) With the correct mandril press it down the tube to expand it for 36mm inserts that suit early Commode Doors . I used HDT spec Bilstein P36 0303's . 4) Buy the threaded adapter from Sydney Suspensions and weld to strut tube . You have to trial fit and cut tube to the correct length . 5) Buy the threaded tubes and lock nuts and weld to strut tube . 6) Weld modified lower spring seat to upper threaded collar . 7) Buy and fit spherical strut top and assemble the units . Option Noltec are Making R30 camber/caster adjustable strut tops - better for road . I personally don't like the Silvia struts in Skylines , the damper section is much shorter and severely limits bump or upwards suspension travel . Decent brakes can be fitted to early struts , DR30 or R31GTS preferably because of the four inch (100 mm) caliper mount centres . Making up new hubs with the flange in the right offset for over stud type discs is a simple machining operation as is re drilling five stud disks . None of this is dirt cheap but neither is the result . My modified DR30 struts owe me around $800-$850 and the car came with spherical camber adjustable strut tops . My brakes are std which is fine for stock car performance on the street . Cheers A .

I would imagine HR31 LSD's are similar if not the same as turbo DR30's . That era of R200 LSD was designed to have some function but not over the top . A propper R200 LSD has four sets of active plates in each side to give progressive and durable (slow wear rates because more plates = more active surface area) use . The std DR30 type only has one active pair of plates in each side (along with the curved or Belville plates to give some pre load) and a spacer to take up the space where the other active plates would have been . To get it working properly the hemisphere needs to be removed and separated from the crown wheel , the spacers need to be flicked and replaced with clutch plates . Belville washers (plates) need to be selectively fitted to get some static pre load on the clutch plates . Don't get the idea that this static pre load is what does the limited slip thing , its the ramps in the hemisphere case and the wedge shaped notches on the spider shafts that achieve this with the drive or torque reaction from the pinion via the crown wheel . What really happens is if you lift a back wheel or it has zero traction the spider shafts won't ride up the ramps and compress the clutches limiting differential action . Static pre load tries to give some very limited drive in these situations , but for this type LSD to work it needs some traction to load it properly first . The ramp angles are quite good on production R200's , same as Nismo H190's and use the same clutch plates , they don't need heaps of pre load ie 40-50 lbs . Mine was set up to about 67 and was a pain in the butt for road , it would drag its bum round tight corners at low speed and try to lock up with very little throttle . These are bad traits in a road car , causes loaded up suspension joints and causes body flex and rapid tyre wear . I learnt all that the hard way with a Detroit Locker diff I once used in a Bluebird , never again . Any Nissan diff specialist , particularly one with rally experience from the past should be able to sort it for you . Cheers A .

It looks like the later , slightly smaller compressor , version of the RB20 Hitachi turbocharger . If it has a bolt head on the side of the bearing housing its a ball bearing type . Note the tiny passage in the turbine housing ...........

I can't speak from experience what works on an RB26 , I've never driven a GTR or RB26 anything . Garrett does make an RB26 specific GT28R which seems to be identical to the Garrett produced and HKS marketed GT2530 . The easiest way to tell a direct fit RB26 (GT28) based turbo is the two holes on the bottom of the compressor covers to mount the plumbing gadget for water and or oil supply . The compressor outlet from memory has a two bolt flange where most single turbo CA/SR/RB engines have a three bolt flange to connect the ducting . There could be a difference with the dump pipe mounting flange bolt pattern , I could be wrong but the exhaust manifold mounting flange is a little offset from the center line of the housing . I do know that the GT28RS's as they come are not a direct fit turbo due to minor differences in the exhaust housing and the compressor cover/adapter ring is a size up (T04B instead of T3) . It can be done but not a cheap option . Prices vary but three grand is tight to supply new and fit , its a lot of work to R/R turbos on a GTR in situ . Cheers A

To give you some idea the GT30 turbine measures 60 by 55mm and the VLT's T3 turbine 59 by 47mm . HKS make exhaust housings for these (GT30) turbines down to .61ARR in T28 flage most likely for CA18DET's and in .73ARR for SR20DET's . It should be a walk in the park to excite this turbine on an RB2500cc with a Garrett T3 flanged .63 ARR turbine housing , provided the compressor wheel is not of too high a capacity requiring more shaft torque to drive than an adequate one requires . The perfectly sized turbo does not have extra capacity for a bit more urge later on without sizeable compromise - lag . Extra urge means extra gas flow needing less restriction , less restriction as well as less gas flow means lower gas velocity and no turbo or I should say turbine exitation when you want it . Have to go , threatening looks from she who must be obeyed and me with no emergency chocolate , cheers A .

The GT3071R is not really a "large" turbo for 2500cc's , if anything it may not pull a lot of boost at the top of the rev range on an RB25 . On a std engine (injectors , computer , AFM) it should do better than the standard turbo because you loose the very restrictive turbine and housing . The 71.1mm GT35 series compressors are not much if any bigger than the std Hitachi's but the turbine and housing are light years ahead from an aero and gas flow point of view . Don't be afraid of the number 3071 , all it means is a GT30 series turbine with a 71mm or GT35 series compressor . A lot of confusion exists with the GT (Garrett Technology) Ball Bearing turbo descriptions . The first two numbers describe the turbine wheel by series eg GT28 , GT30 , GT35 , GT40 etc . The second two numbers describe the compressor wheel in either series ie 35 , 37 , 40 or outer (major) diametre ie 71.1mm , 76.2mm , 82mm . The fact that the Garrett re sellers use their own number system mucks it all up . Using the original system the GT3071R should have been called a GT3035R using the wheels series numbers instead of diametre numbers in mm . Garrett also are guilty , their GT30R is really a GT3037R . Off the top of my head I can think of eight different compressor wheels that can be had with the GT30 turbine so arguably they're all GT30 turbos but they don't all do the same thing . The GT3071R has the smallest (but not tiny) compressor option of the GT30 turbine based turbos . Also the "R" on the end stands for rolling element twin ball bearing cartridge or CHRA (Centre Housing Rotating Assembly) . Whats the next size down from the GT3071R , probably one of the GT2835R series which goes down on turbine size - bad in my opinion . I think the smaller .63ARR exhaust housing on the GT3071R would work better . The power rating on them from memory is 430-450hp at the crank based on compressor flow , a lot of turbos are rated this way with total disregard for turbine flow - or the lack of it . The big advantage of the GCG Highflow is that its externally identical to standard so one out one in and no expensive one off bits to make it fit . What it dosen't have is current technology wheels and housings though having said that some here have had good results with them . Those "STR" style ball bearing turbos use older type Garrett bush bearing wheels and the big sell was that they're re buildable ball bearing turbos . From what I can tell they use the large trim or Stage 3 TA34 turbine and a late evolution seven bladed T04B 71.1mm compressor wheel (299-4) . My opinions only , cheers A .

I dont know much about the 1JZ but would be interested to find out the bore , stroke and rod centres length . To explain my preference of the GT3071R . I prefer the closer turbine diameter to compressor diameter match ie 60mm/71mm . Secondly Garrett do .63 , .82, and 1.06 ARR turbine housings for the GT30 turbine which gives you the ability to tailor the velocity of the exhaust gasses through the turbine to suit your boost threshold requiremnents . The larger turbine stands a better chance of developing more shaft torque and less restriction to flow . You can always put a smaller exhaust housing on a big turbine , putting a larger exhaust housing on a small turbine is not the same thing - less restriction , less shaft power to drive the compressor . Cheers A .

Actually the main difference between the GTRS and the GT2835R's is the turbine . Both of these turbo's use varying trims (52T - 56T) of the GT35 series compressor which is 71.1mm OD . The GTRS uses a 76 trim version of the 53.85mm NS111 turbine in a .64 ARR GT28 turbine housing . The 2835's use a Garrett hybrid turbine that's actually a modified GT30 turbine . These start life as a 60mm UHP (ultra high pressure ratio) turbine which is factory cropped down to 56.6mm OD and is about the turbine size limit of the GT28 exhaust housing - without totally killing the nozzle section . They are made in 84 and 90 trim and have .64 and .86 housings to suit . All of this was a bit of a desperate by Garrett to fill the void between the 53.85 and 60mm turbines - in other words too much turbine inlet (back pressure) and not enough shaft torque for the larger trim GT35 compressor wheels . Note that HKS uses the smallest compressor trim (52) in the GTRS with the small turbine . The hybrid turbine is a bit of a dog because the hub section is a bit big (restrictive) and heavy for the length of the blades , GT28 housing really a bit small as well . For an engine needing a T3 exhaust flange there are few GT28 housing options ie the .64 from the HKS GT2530 or the expensive .68 and .87 from the 2835 Pro S . In my opinion the Garrett GT3071R is a better bet , it uses the non bastardised GT30 turbine with the same GT35 56 trim compressor as the 2835 . If you need an integral waste gate HKS do a T3 flanged .68 and .87 version for their GT3037 Pro S turbos which you can buy seperately . If you look at the Garrett Catalogue PDF it shows the 3071R CHRA and a couple of compressor housing options . Cheers A .

The basic GT28R from Garrett goes in easily and works well , rated at around 290-300 crank HP . It is very similar to the BBGT on the S15's , slightly different compressor trim . For a bit more urge you could fit the GT28RS , ATP Turbo now offer them with same compressor housing as the GT28R ie the Nissan 3 bolt flange type . Dont be afraid to use the larger .86ARR turbine housing as low down response is not in any way lacking with the RS version . The 16-1800cc Honda people in the states love them . Cheers A .

Hi all , have to agree some mods forced by limited budgets can be very effective . Some time back I had DR30 IRS grafted into a Bluebird and remember thinking the crossmember bushes were too soft . The budget fix was to drop the rear end out and fill the gaps in the rubber bushes with of all things stickerflex . This stuff has very similar consistency to the rubber and is the cheap way to get a "works" style bush that still has some compliance . I have seen a few HR31 IRS rear ends and their X member bushes are REALLY soft . This will not help with tramp or alignments .

I'm not sure if such a thing exists . Does anyone know if the V8 Nissans used an R200 differential ? Cheers A .

The point I'm trying to make is I probably can't get a 3.7 to 1 ratio short nose differential to suit an R32 GTST so a 4.1 with a larger diametre tyre may go close . About that .92ARR housing , is that a propper GT35 housing ? Cheers A .

Joel I think you'll find the VLT had the wide ratio ( ute pack !) gearbox option meaning shorter gearing 1-2-3 . Actually , got a copy of the Holden 3.0ET (Vol 6) manual that states MX7 ratios are 3.580 , 2.077 , 1.360 , 1.000 , 0.760 . When used with the 38/11 (3.454) final drive the overall ratios are 12.367 , 7.175 , 4.698 , 3.454 , 2.625 . From memory the R32 GTST Manual uses a 4.36 final drive and the gearbox a 3.321 1st gear ratio making for 14.479 overall , 2nd 8.288 , 3rd 5.703 , 4th 4.36 , 5th 3.309 . My master plan was to have the VLT's 1st gear ratio (overall) but with the closer ratio gearbox . So divide 12.367 by 3.321 which gives 3.724 as my ideal final drive ratio . I've yet to dabble in the later type short nose R200 differentials and have not heard of any with taller ratios than 4.0xx . The later Nissans were using larger diameter rims ie 16+ whereas the earlier types ie R30/31 , S12 , 280Z , Z31 were on 14's and 15's . I'm sure a look at tyre rolling diametres and available differentials should get me in the ball park for an R32 . I'll probably need to look into up a ratio (4.1 ?) and up a tyre profile to 60 series . The only GTST I see on a regular basis wears either 225/55's or 205/55's on the std 6.5x16 rims , can you tell me what is standard . Cheers A .

To do that is very easy , since the ceramic turbines are the same just exchange the exhaust housing on the RB25 turbo for the VG30 one . Going inside these Hitachi cores seldom works , the big drama is retaining the ceramic turbine when torquing up the compressor lock nut . Mostly the turbine pops off the flanged (hot side end) of the shaft where it was bonded together . Its usually cheaper to replace these cores when they die with another one than it is to attempt repairs . I've never seen the R34 GTT turbo except in the above mentioned post . Nissan would have taken full advantage of the Neo engines more sophisticated engine management and variable cam timing , which would allow the turbo to have higher gas flow and not loose low end torque . From memory the RB25 Neo made 206 KW and the earlier version around 185 , I suspect the R34 turbo was altered to support this . I am curious to know what the power curves are like between the RB25 Neo and the std RB26DETT . Cheers A .

Most eventually discover that high boost pressures and low compression ratios are the worst combination . Modern turbos are more about good gas flow and transient response than the old dogs . The best way to do it is to throw as much capacity as is economically feasable (L28) and use a more friendly compression ratio ie 8.5 - 9 to 1 . Then add a decent modern turbocharger ie GT30R and forget about stratospheric boost levels . At 9 to 1 CR and 10 lbs of boost the torque should be quite impressive . Provided you used a turbine housing with a good balance of boost threshold vs turbine inlet pressure part throttle torque/fuel consumption/throttle responce should be good . SK is saying in another part of this site that boost pressure is merely resistance to flow meaning that removing the restrictions gives more performance for the same boost pressure . It is easy to forget that in the search for high boost we often create our own detonation dramas requiring drastic octane/fueling/intercooling requirments .

Out of curiosity what do OS do about the cooland water passages (block and or head) if the liners have 5mm wall thickness ? Cheers A .

Yes I'd like to know too , I gather the later cranks are wider across the flats that drive the oil pump . Or is there a difference in diameter as well ? Cheers A .

Yep .

There are people around doing laser cut optical disks for the FJ20 CAS . I opted for Autronic SMC because the software is better charge temperature wise and the Haltech people dont seem to understand the importance of sequential injection . My SMC is for sale , complete with late style FJ20 CAS laser cut disc . Includes coil ignitor TPS relays loom etc . PM for details .

VATN or variable area turbine nozzle technology has been around for a while mainly used with Diesels . The housings and vanes are expensive to produce (high temp materials expensive) and the higher exhaust gas temperatures of petrol engines cause reliability problems . The theory is that a variable area radius ratio will give less turbine inlet pressure in relation to boost pressure so there is less restriction to gas flow through the engine . An American firm Aerocharger did market them for a while but they seem to have disappeared . Corky Bell talks about them , and a lot of forced induction theory , in his book Maximum Boost . I'd really like to see an update to his book with todays more modern turbos etc . Cheers A .

Yes have to agree , the FJT is a bit dated by todays standards . From the few people I know who got large power numbers from the OX , derestricting the exhaust side was critical as was turbo selection . One I do remember did 700 crank HP on an engine dyno but it was no boulevard cruiser . I think it used oversized valves , a fair bit of porting on the exhaust side , fairly big cams , a TA45 Turbo and 1.5" bore steam pipe exhaust manifold - the external gate was a large HKS ie 50 - 60mm . It had a custom inlet manifold with a huge throttlebody and huge Rochester injectors . With OEM cams I think you'll find the lobe center lines is slightly more aggressive on one of them I think the NA inlet cam , it wasen't just the phasing that was different . Also you may find the NA compression ratio is higher than you think , I have seen numbers in Nissan manuals mentioning 9.1 and 9.5 at least for the S12 version . I would look into the GT30's exhaust housing , I sincerely hope you'r using a propper GT30 housing not some machined out substitute . If so you could look at the largest 1.06 ARR housing which may help but as SK mentioned head and cam upgrades do pay off . There is a golden rule with efficient turbocharging - keep the exhaust manifold pressure down to somewhere near boost pressure . You should take a line off your exhaust manifold before the turbo and run two pressure gauges to compare exhaust and inlet manifold manifold pressure . If you have major restrictions they'll show up . Cheers A .

$64 question that one . My guess would be they wanted a bit more flow potential particularly on the exhaust side at the expense of some lower mid range . You could look at the applications as a 2000cc 4 cyl compared to a 1285cc 3 cyl by two . Thats why the housing AR Ratios and comp/turbines are different . Cheers A .