discopotato03

I'd be getting it tuned before anything else so you have a base line to work from , does it run a PFC or other tunable computer ? Cheers A .

Yes Ceffy thats exactly what mine looked like from the back only with the slightly larger RB25 type turbine housing . All RB25 turbos had larger comp covers than RB20 types which is not surprising because all the air goes through it and RB25's are 25% larger than RB20's .

No offense taken , my point is that using the full stroke of the master cylinder when bleeding brakes pushes the pistons and cup seals further into the cylinder than normal running use . Yes I do know what a spongy pedal feels like and no I don't flog the hell out of cars on the street because I have this thing called mechanical sympathy . Cheers .

I was under the impression that all the RB ball bearing ceramic turbines were the same , any pics or dimensions ? Cheers A .

In the past HKS marketed the GT3037 (GT3076R - Garrett speak) in 48 and 52 trim along with the far more common 56 trim compressor . The 48T version seems to have fallen off the edge of the planet which is a pity . The 52 trim version is the sweet spot and quite a few Americans have found this out on their SR20's . I used to haunt their SR20 sites in my FJ20 days and they often said that the spool or boost threshold characteristics varied by 5-600 rpm between the 52 and 56 comp trim 3037 versions . 5 to 600 rpm makes a HUGE difference on a 2 Litre four , more so than the few mm of inducer size and drop from .60 to .50AR compressor cover size would have you think . They still flogged approx 400 wheel Hp out of the "Japanese Coventry Climax Pump motor" so the optimal trim GT3037 is no whimp . Even though Garrett manufactured the GT3037/GT3076R they were only sold to HKS in those days . Garrett fobbed the rest of us poorpers of with the pathetic GT30/TO4S variants which are still with us and finding more victims . In the recent past Garrett decided to offer the GT3076R to all but only in 56 compressor trim . I was talking recently to someone who worked for Garrett in the US and he said that market forces have a large say in what they make and sell . They narrowed the GT3076R in the US down to 56T because thats what the market demanded so thats what they produced . So sady mores law means that only the laggy 56T is reasonably easily to obtain . Nothing stopping you buying a 52 trim GT3037 and flicking the T28 flanged turbine housing for a T3 flanged one but its expensive . The point of all this is that HKS offered smaller trim compressors and turbine housings down to .73 and .61AR so that they would be good responsive things on CA18's , SR20's and probably RB20's/25's . We've been lumbered with the sledgehammer for walnut option so now you all know why the GT3076R/GT3037 56T turbos are so laggy on SR20's , RB20's and RB25's . Cheers A .

Yep plenty used them as a Hi Flow basis , mine had an 8 bladed TO4B -24 compressor which was a bad move . I was not clued up in those days to the fact that the 8 blade wheels were intended to be used with larger TO4 turbines and were low speed wheels . The 6 bladed B series wheels worked much better because they don't try to pump as much air at low wheel speeds where the turbine is not really developing enough shaft torque to be responsive . Also the extra air from the 8 blade wheel tends to make the turbo surge prone when it does come on boost . I think I still have mine buried in the cave so I'll try to get some pics of it in a couple of days time . It had a VG30 turbine housing and RB25 style compressor cover at first then an RB25 turbine housing because it was very laggy . The RB 25 housing brought it on earlier but made the thing surge as well . Too much air too early . As always its a but dubious using bored out non native turbine housings and I'd say the original Hitachi's were probably the only ones designed for it . Anyway that turbine being reasonably large (and heavy) won't be real good for a 2L six and the high oil shear drag from the bush/plate bearing system just makes it worse . I won't say it couldn't work on an RB25 or 30 its just not an optimal basis to begin with . Often you find with any used bush bearing turbo shaft and or housing bore wear and rear piston ring seal groove wear . They may be cheap or even free but the costs mount up down the track . In some ways you can see why companys like Garrett prefer to sell a complete cartridge rather than bits for rebuild . You get factory tolerances and brand new bits and refitting the housings is easy and quick - lower labour costs if your paying for it . Do your sums very carefully because if you start playing with things like this you can often end up paying more money for less performance/satisfaction/dinosaur technology . If I was trying to do it on the cheap I'd stay with factory type turbos or at least a combination of factory bits . I always thought the RB25 turbine housing on the R32 turbo would be a cheap easy upgrade but thats only a guess . Cheers A .

Hard to say if the composite type one was any better than the aluminium ones though I did see a number of damaged late types some years back . At the time I wondered if the composite wheel was a weaker link than the ceramic turbine but without knowing the circumstances in which they died its impossible to tell . It is worth noting that the R34 RB25 made more grunt than any of the R33's though changes to the engine were made as well . I'd say they removed some of the restrictions in the system and covered any loses with the superior VCT system . I wouldn't mind seeing the pics of the R34 GTT turbo mainly because I'm interested in the different - larger ? comp cover . Cheers A .

Do these go straight into an S2 R33GTST without any mods ? Cheers A .

Hi all , been sniffing around Michelin tyres to find a good balance of reasonable price/best performance . I stumbled on the newer (2006 vs 2003) evolution of Michelins Pilot Preceda or PP2 and it looks pretty good so far . People say its quieter than the PP1 and its outer tread pattern is supposed to be or work similar to their Pilot Sport tyre . The Michelin Japan site reckons its water dispersal abilities are improved and load balance across the tread is superior . The same person said not quite as sharp a turn in as "brand B" but far better grip and lots of warning at/near the limit of adhesion . Nuff blurb . My usual tyre haunt sez yes they are around but probably not in 235 45 17 till early next year . I don't think there will be a 245 45 in 17 but 235 on 8.5 rim should be alright . Any info and opinions ? Cheers Adrian .

I've seen mechanics renew fluid by the gravity method and it worked fine , have not seen it done on a Skyline . I don't know about it bleeding air out . I have seen old masters stuffed by using the full stroke when bleeding the system . I believe if there's a lip on the master bore and the seals are pushed past it they can tear and not hold pressure . I would not stuff about with a worn master cylinder , its your life and that of others that depend on it working properly . Cheers .

Edit , should have said quoted power by airflow was 490 for HKS GT3040 and 540 for GT3240 . Cheers .

From memory the S4 and S5 turbos were Hitachi HT18-S by name . Neither had a T3 mounting flange and one or the other had a twin entry turbine housing . Rotors hate backpressure which is why their turbos are large on the exhaust side compared to 4 stroke piston engines . So they are not really suitable for an RB20 though many have used them as the basis of high flow turbos . You could look at their centre section as a T3 copy with a pretty healthy sized turbine . The comp wheel is quite small as is the compressor cover . They are not a total loss but any potential they have may not be cost effective unless alternate compressors and housings are cheap or free . For an RB20 I'd give it a miss . Cheers A .

This one seems to do the rounds so I'll throw in my 2 cents . I know exactly how 80's era production turbo engines feel because I lived with a bog stock (catback aside) DR30 FJ20ET for a couple of years . These did not have the throttle closed recirculation valve . It used to do weird things on a trailing throttle after running in boost at lowish engine speeds . You could back off the accelerator and on over run you'd get a bit of engine braking followed by a kind of mild surge probably caused by the volume of pressurised air between the compressor and the plenum not letting manifold pressure drop as quickly as desired . If it had been fitted with the manifold vacum operated throttle bypass valve air in the system could do the roundies (from compressor through the valves by pass plumbing back to the inlet side of the compressor but down stream of the air flow meter) . This means the compressor has somewhere to send positive pressure and recover this air but on its inlet side . Apart from the fact that presurised air is not trying to overwhelm the plenum in the throttle plate/s closing phase , the air flow metre is out of the loop ie not measuring much flow so the computer is not telling the injectors to inject fuel thats not needed . My personal belief is that manufacturers fit this bypass recirc valve for three reasons . 1) Emissions - blind Freddy can see filthy rich overrun mixtures serve no useful purpose . 2) Drivability - when you close the throttle/s you want the engine to back off cleanly , not dilly dally . 3) Noise - Manufacturers have no interest in the bionic Baygon can effects of atmo BOV's/comp chatter There are very good reasons for having the Factory or better systems in road cars . Sharp predictable throttle response is important as is good mixture control . Race cars are a very differend breed and lowish speed antics are less of a problem because its not where they are in the heat of battle . For them compressor stall can be a problem though modern turbocharger systems are a far cry from the RS500 Sierras - which were a dogs breakfast in reality . Its getting off track but the homologated TA34 turbo was layed back heaps along the leading edges of the compressor blades to help stop them bending under rapid transients and high boost pressure . A turbo like a GT3076R would have made all the diference . In a nutshell you have nothing to gain by removing the recirc system . If anyone wants a quick back to back remove the vacum hose (plug the hose too) and go for a quick spin . Don't blame me if you damage something by disabling a devise designed to prevent real issues though . Cheers A

Hi Roy , no negativity intended - just thinking out loud about RB26 heads . If you want it to be a sleeper I guess that means 25DE head with 26 or R34 25 valve gear . I have no doubt the real GT3076R (turbo no 700382-0012 / CHRA no 700177-0007) could do it but it may need a little fine tuning with turbine housings . I think HKS used to do T3 flanged GT30 turbine housings but the T25/28 flanged versions are more common . As was mentioned HKS's .87AR size would be a good starting point with 1.01 and 1.12 still to go . HKS's housings are more compact than Garretts and a little better nozzle shape . The Garretts are not bad though AR sizes jump from .82 to 1.06 . I don't think I've ever spoken to anyone using the large 1.06 housing on a GT3076R but that doesn't make it a bad thing . Cartridge wise the GT3076R and the 56 trim GT3037 are identical . Occasionally people in the States buy GT3076Rs with 3037 stamped on the ID tag . Technically speaking Garrett US sell the GT3076R minus the turbine housing and you select which one you want . HKS sell turbine housings seperate so if your lucky you can get the best of both worlds . Only grey area is can you find HKS T3 flanged housings . Also note that the HKS version uses a slightly smaller four bolt flange than the Garrett . I have seen pics of the Garrett housings remachined at the back for a V band flange . Have a look at ATP Turbos site for some pics and ideas . Personally I'm not a big fan of the GT3040R though the HKS variant as mentioned with the 82mm 50 trim GT40 compressor is the better choice . I have some paperwork somewhere suggesting that the GT3240 was good for 490 Hp but its very much an orphan with its cropped GT35 turbine and 54 trim 82mm GT40 compressor . The only turbine housing made for it , I think , is a HKS .87AR T25/28 flanged one as it was probably aimed at SR20's and in twin form on RB26's . Not cheap either . Cheers A .

Hmmm , well Watson we'd probably have doubts about using a hydraulic head to 8.5k so the evil Moriati may have the gun head in the wings ...

Has anyone used these tyres on the road yet ? Not too much info available online but the word is very good for the brass , does this mean very good for the price or good and cheap as well ? Has been mentioned not famous in the wet . Cheers A .

Is there any chance of grafting an R32 RB25DE head onto it ? A lot of work on the cooling jackets and not shure it the valves would clout the block . Damn it Roy can't you sleeve the 25DE block back to 78 so you can sleep at night ? LOL ...

My last car was engine wise a bog stock 84 DR30 with its FJ20ET and dinosaur T3 non water cooled turbo . It ran std boost and was never pushed and shut down . I don't use $4.50 supermarket oils . I had it from 85K to 105K with no issues at all . Was it luck or ...

Sorry not in SA in Sydney and can do better than $500 . Will PM . A arms and R200 half shafts are most likely spoken for . Cheers A .

Yes a big ask from a 2L six . How far are you prepared to go/spent to get it there Roy ? Probably needs a really flying head and healthy cams to get there . Its fair to assume that the GTS-R's exhaust manifold is good considering it was designed for the Grp A RB20 . Does anyone know what spec the GMS R31's ran and what sort of power they made ? Cheers A .

Lost another long post to ##&&*%$@#n Wi Fi . NFI , EGT's at part throttle cruise or idle are not as cool as many like to think . The whole lean excess air factor thing usually means toasty EGT's no doubt to help the cat converter do it job . The turbine/compressor speed is not really proportional to boost pressure because while the inlet manifold pressure may be constant mass airflow through it rises with engine speed . If you draw a horizontal line across a compressor map representing constant pressure the speed lines fall off to the right hand side of the map . As our engine accelerates its air demands go up and to keep a head of pressure across the inlet manifold the compressors speed must rise otherwise boost pressure drops . Cheers A .

Will you sell HKS exhaust manifold seperate ? Cheers A .

Found time . Cheers A .

Zip Zero Zilch . Effective water cooling is your turbos best friend . The thermal mass of the centre section in most peoples turbos is quite small , provided you can get its water coolant supply to thermosyphon properly when the engine is shut down you should not have oil cooking issues . Ball bearing centre sections have an easier time because the balls and races are hardened steel and the surface contact area is much less than bush / plate bearing turbos . A properly designed turbo water cooling system does not allow the cartridge to get hot enough to fry the oil in its bearings . I have a diagram on another PC that I'll post up later time permitting . A while back I put an uncharacteristically long speil on one board about how I rigged up water cooling to a GT28RS on an FJ20 , when I mentioned that you could easily hear water boiling in its jacket (turbo) after shut down people there had hysterics . I could not make them understand that it was set to allow the steam bubbles to travel up the water outlet pipe into the heads highest point , just inside of the thermostat , out the top hose to the radiators top tank and via the rad cap to the overflow tank . It only did this for the 1-2 minutes that was needed for the coolant to drop the turbos cooling jacket (basically bearing housing) temperature below 100 deg C . The turbos water inlet was plumbed into the blocks coolant drain bung hole which is often the lowest part of the engines cooling system . Cooler water is denser and heavier than warmer water so it made sense to get water from this point . It thermosyphoned perfectly and worked automatically . There are going to be times when an engine has to be shut down pronto to save it from some terminal problem ie major oil / coolant / fuel leak and its instances like these that an effective turbo water cooling system saves its bacon . As Corky Bell said manufacturers fit them because Joe average wood duck refuses to use good oil (and change it often) and demands to be able to exit his mobile kelvinator (which afterall is just another house hold appliance in his eyes) post haste . Waiting around for the pesky hair dryer to compose itself is for squares man . The turbo timer is a marketing tool to separate you from your money . The water cooling system is used to prevent the turbos centre section from getting hot enough to be a reliability issue . Manufacturers have to put warranty on their cars so reliability is important . Cheers A .

Does anyone have pics of the Neo RB25DET chambers and piston crowns just so we can compare . Thanks A .