Dale FZ1

You have PM. I would be interested in a radiator with built in oil cooler (liquid:liquid). Price dependent on level of interest. cheers Dale

Abo Bob I know/understand many people rave about the qualities of Redline products. I suspect that they really are very good, as well they should be at the cost. Smurf's blood? Is that stuff blue? Basically my fault diagnosis has examined the value of replacing the oil a couple of times to purge contaminants. Even tried ATF just to see how a really light lubricant might work on suspect synchros. With minimal impact even with that (temporary) trial, I would say playing with brands of oil is likely to be an exercise in buying time. Having said that, the Molybond I put in the oil has made the change quality better. I've bought this car to do a few track days per year, and if I can't expect that the box will change flawlessly at high rpm and temps in those conditions, it is painful to use only for gentle commuting. I would replace the synchros that NEED replacing, but closely examine the condition of all to see if they were suspect at the same time. My bearings etc are not at all noisy but the idea in an overhaul is to disassemble/correct/avoid problems only once. Any links to the necessary workshop manual would be great please. cheers

My ECR33 did the same thing fresh off the boat. On advice I got a can of Subaru inlet manifold cleaner (really just a top grade carby cleaner type solvent) and emptied the can through the inlet as per the directions. Fixed the hunting idle. I suspect the gum that is introduced into the manifold via the PCV is the problem. Slip off your crossover pipe and wipe a finger inside the plenum while holding the throttle butterfly open. FWIW, I know BMW and Subaru specify the use of that "service in a can" as part of their schedule. At $20 max it's worth a go. cheers

Thread search here has not come up with heaps of information, so here goes: Over 9 months of running I found two gearbox problems, normally only surfaced when the ambient temps were high >30 deg C and giving the car a squirt. Quick on/off throttle movements and/or changing gears at rpm >6000. The probs were only occasional and not repeatable at will. First prob was it tended to pop out of 3rd gear on decel. Second prob was it would occasionally baulk at upchange either 3-4 or 4-5, as if I hadn't used the clutch. Changed box oil with 75-90 mineral oil, no change in box operations under the stated conditions. Original oil as it came off the boat did have some metal filing contaminants and was a bit dirty but not overly so. Changed box oil with ATF for 1000 km trial. Did not experience baulks, but did get a couple of 3rd gear pop outs. This was during a South East Queensland winter (cool but not cold). Removed the AFT and returned to the Shell mineral gear oil, deciding that there may be an issue with detents and probably with synchros. Extra preload on the detent has given heaps better shift precision but a bit slower action. The baulking problem remains so I'm about to start planning a box rebuild pending a trial of Molybond additive. Here's the question: given the differences between the RB25 box and either RB20 or RB30, are the seal/bearing kits and synchros readily available? Anybody with first hand experience I would be interested to hear. Also other advice I've had suggests genuine Nissan synchros are made to more consistent tolerances with better results (if more costly). Any experiences here are also wanted. cheers

What sort of work is required to adapt T28 to the T3 exhaust flange? There is not a large variation between the two. Also have you seen the SR20 dumps successfully fitted to a Garrett? cheers Dale

Got pics for the manifold?

Still available, or sold?

You have PM. cheers

Do you still have the AFM? PM me please.

Search the forums for previous comments. Also pick up the phone and freecall Shell Australia to speak with a techo. Basically oils have to be working in a certain temp range. Too cool (approx sub 80 deg C) and sludging can be an issue. cheers Dale

Great result quincy777, and right on target. Couple of things I would like comment on if possible: what sort of flange adaptor did you fabricate, and how did the turbo - suspension tower clearance work out? what did you do for a suitable dump pipe what is the boost threshold point (ie when does it go from vacuum to pressure) how quickly does it build boost (once on boost)? Looking for comment about whether the power is controllable cheers Dale

Thanks for the comments, since I wanted to keep the thread going and get the whole picture. Turbine maps and size matching has significantly more science to it than it first appears. Getting the turbine speed range “right” ie. So that it is running the compressor in its required speed range to deliver sufficient airflow into the engine to produce the target power output seems easy. Turbine size selection is simply such that it will generate the required shaft torque to push the required mass of air – correct? Not entirely as it turns out. Checking my own understanding, I had to review what characteristics seem to point towards a good engine-turbocharger match. Quick acceleration of the rotating assembly is a prerequisite to good engine response. Discopotato had earlier bandied the suggestion that sizing the turbine and compressor wheels within a “rule of thumb” 15% would yield a responsive turbo. This led to some posts about relative wheel sizes in various Garrett and HKS models – ignoring for the moment the actual specs of the housings they run in. The figures showed that the GT2530 / GT2560 twins had the least difference in relative size, and they enjoy a reputation for exceptionally quick boost response combined with power potential of about 320hp. Lots of happy owners using them in RB20, RB25 and SR20 applications too. The figures also showed the larger, higher flowing models commonly fitted to RB25, 26, and 30 had a fair deviation from the 15% “rule”. One model, the GT32 (note no R suffix indicates a plain bearing construction) fell inside the 15% relativity of matching, and I found it listed by turbomaster.com as a recommended fitment for a heap of different European diesel engines. Nowhere could I really find anyone who had fitted it to a performance type engine despite a power rating up to 400hp. So how do you make sense of that? Firstly the primary difference between compression and spark ignition engines is that conventional spark ignition engines are throttled. That means airflow into the engine is controlled by the throttle valve(s) and the engine will not ingest the full volume it is capable of until at WOT. The diesel engine cops the full amount with every inlet valve opening moment. Power is controlled by the volume of fuel introduced into the combustion chamber. As Discopotato indicated, the effective engine rpm range of a diesel is limited – giving the engineers a very good opportunity to size their turbos to work within a narrow range of efficiency. Quick wind-up is comparatively easy, because a change of (for example) 500 engine rpm can have them going from a loafing cruise and into maximum load/torque production. And they are further improving that with the introduction of VNT – variable nozzle turbine. Slightly off track, but the point is our beloved RB engines work over a much wider rpm band. Not only do we find a quick wind-up desirable, but we also want the flow and efficiency to stay high when the revs are high. Next I went into a bit of high school physics research to relate back to sizing and transient response and the 15% idea. A couple of terms came up that should be remembered – centripetal force, centrifugal force, and polar moment of inertia. They are worth doing a Google search just for your own knowledge, but the most significant finding was confirmation of an assumption regarding wheel diameter, wheel mass, and acceleration of rotating assemblies. The mass of a rotating object is a determinant (along with velocity) of the amount of kinetic energy it stores when turning. Diameter does not impact stored kinetic energy. Also the forces acting on a rotating body act inwardly towards the rotating axis. ie. A spinning turbine will have perfectly balanced forces acting towards the centre of the shaft it is connected to. This explains why they can spin at up to 180000 rpm without failure. The big one is that a larger diameter body of the same mass will offer greater resistance to a change in rotational velocity than one where the mass is more concentrated (ie closer) around the rotating axis. This means a smaller diameter turbine will generally offer a significant advantage in acceleration. The trade off is in a likely decrease in overall flow capability of the turbine unit vs a larger, less accelerative turbine. This is something not unexpected if you were attempting to compare (say) a 280hp unit with a 600hp unit. The lesson emerging from this is that the turbine unit to suit a relatively small, quick revving RB engine must also be relatively small in order to quickly accelerate the compressor – overcoming the polar moment of inertia of the WHOLE ASSEMBLY. Being a “slave” to the compressor, the turbine must simultaneously be big enough to generate the torque to drive the compressor which shifts the required volume of inlet air, while being small enough to have a low polar moment. Getting these ideas straight ends up giving long posts, so apologies again.

Bump Engine still for sale? Pls PM me

So what do you look for in the model coding to determine whether the compressor assembly is the "true" GT series? As a bit of an aside, I have seen a GT32 listed, which is a plain bearing, internally gated job with the T3 flange, matched to a reasonable spec 71mm compressor assembly. With a 64mm turbine, is this a viable alternative to the GT30 models for Skyline? cheers

After a reasonable amount of research, I found a few pearls that are pertinent to this topic: Compressor matching (to the required engine + power) is universally accepted as the first (and most important) activity. Plotting flow and pressure ratios on various compressor maps and interpreting them can provide some challenges, especially when trying to keep out of the surge area and get good performance under partial load/throttle conditions. Compressor capabilities are established through a combination of wheel and housing specifications. Wheel diameter and trim must be considered – the larger trim has a bigger “grab” at the air, allowing greater air mass to be compressed. A larger diameter wheel generally pushes more air for a given turbocharger rpm. Housings with smaller A/R numbers are employed in higher boost applications due to their flow maps being extended upwards to the right (higher flows @ higher pressures). Evaluating turbocharger matching to a road car engine is generally accepted as a measure of its ability to deliver the required power at WOT, as well as relatively elastic (read: quick) boost and engine response at low to middling engine rpm and throttle. This is where understanding turbine maps and establishing the capabilities of the compressor and turbine combination is essential if you want something that is a capable all rounder - rather than excellent in one area but falling rather flat in another. The concept of “average power” and reviewing the total area under a curve rather than peak values has previously been discussed on this board. I struggled for a while to advance my understanding of transient turbocharger response (ie. what happens in on/off throttle driving conditions) until I took notice of the compressor speed lines on a compressor map. Plotting your points required also tells what speed range the whole rotating assembly has to operate in so that the engine delivers the desired power. Taking note of that speed range, the turbine selection/evaluation process becomes less difficult when the way it operates is appreciated. The turbine wheel/housing assembly presents a restriction to free exhaust flow when under load, thereby accelerating the wheel. Energy is transferred to the turbine wheel (causing acceleration) as the pressure drops when gases dump through the vanes and into the outlet. A properly detailed turbine map should be produced as a multiple series of discrete flow curves according to the turbine speed and pressure ratio. Go to Borg Warner’s site www.turbodriven.com/en/turbofacts/design_turbine.asp to see what the words here are attempting to describe. What is generally done in fact is that a single curve is drawn as a representation of the mean mass flow over a specified range of turbine speeds. Think of it as a “smoothing” of the maximum flows recorded at various rpm to simplify the map. Turbine maps that are released by Garrett differ in what I would say are two important ways – firstly the maps have the smoothing characteristic as described, and therefore omit information about the speed ranges are required to produce a certain level of efficiency. Secondly, only the maximum efficiency figure is quoted rather than producing a second y-axis scale for efficiency. Go to www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT30/GT3071R_700382_3.htm for an example to compare the detail. The issue is that the turbine will only be operating in its maximum efficiency range some of the time. The match of turbo-engine entails matching the compressor to the engine airflow requirements, and the turbine must match the compressor’s drive requirements to achieve targeted boost response characteristics. This means you need to know the compressor’s expected operating speed range – and by implication the turbine’s required speed range. With turbine rpm controlled by a wastegate, it may be too slow to be driving efficiently, leading to slower than desired shaft acceleration, and thereby produce laggy boost response. Maintaining and/or accelerating to the required compressor speed is critically important, with another site at www.automotivearticles.com/Turbo_Selection.shtml giving some good information. Apologies for the long post.

Its also surprising what you can find at a hydraulics or gas supplies shop. I picked up something similar from Enzed some time back. Not cheap, but it was oil/heat/pressure compatible which rubber door stops or chair ends are not. cheers

I picked up the possibility of the existence of such a beast - just could not locate anything in the Turbobygarrett.com catalogue, or the link to an older cat. (circa 2002) that Discopotato suggested. When I digested his information about the two different housings (UHP, and NSIII), it appeared that the internally gated GT30 housing fitted to the GT3071R was a compromised beast, milled out to accept a cropped version of the 60mm turbine - done because everything was being made to go together when not originally designed to do so. Also note that there is no similar rotating assembly found in the HKS offerings. I'll keep looking and if anybody can find the link to confirm the existence of a 71.1mm; 60.0mm combination please post it. Also bear in mind that the original intent here is to investigate the relationship between turbine maps and compressor maps, so further comments please. cheers

Yes, they should fit, same as for RB20DET. The Splitfire number is SF DIS-001, but I can't recall the Nissan factory number. s.2 R33 onwards have a detail difference and the pin order on the plugs is different to account for elimination of a separate igniter box. Check out either Nengun, or Kudos Motorsports here on the board for price/availability and model applications. FWIW, check the search function and you will see that an easy, temporary (very temporary) fix, or method of fault finding is to remove your coils and wrap wide insulation tape around them to prevent arcing. Firstly though, get a turps rag and wipe off any grime and soot, then get some electronics contact cleaner and spray in the connections (loom + spark plug end) to give it the best chance. Best of luck, but when you are getting misfiring, there's a good chance its time for new coils. Nissan are not the only brand to suffer this problem - its related to the age and positioning of the components. cheers

Well checking out the various models available, here is a run down of the relative compressors and turbines sizings, with the % differences: HKS GT2530 60.1mm; 53.8mm 111.7% GT2535 69mm; 53.8mm 128.3% GT2540 76.2mm; 53.8mm 141.6% GT-RS 71.1mm; 53.8mm 132.2% GT2835 71.1mm; 56.5mm 125.8% GT3037 76.2mm; 60.0mm 127.0% Garrett GT2860RS 60.00mm; 53.8mm 111.5% GT2871 71.0mm; 53.8mm 132.0% GT3071 71.0mm; 56.5mm 125.7% GT3076 76.2mm; 60.0mm 127.0% Laid out bare, it is fairly clear where the model similarities between the two brands are, but all is not as it seems with variations in wheel trims, housing A/R, and flange sizes. HKS have evidently targeted certain niches with turbos that can bolt up to factory manifolds etc and give definite results for specific models, while Garrett offer greater opportunity to tailor various models. For the sake of this discussion however, it is obvious where and why some models enjoy the reputations they do in respect of transient response. The “little” HKS 2530 and Garrett 2860RS (aka Discopotato) have relatively very similar wheel sizes (comp:turbine), and the write-ups about various cars running them suggest a linear power delivery and engine response like a bigger capacity naturally aspirated motor than a more “traditional” turbo job with massive mid range and top end. The one aspect that does interest me from a technical viewpoint is the evident turbine:compressor drive efficiency that the larger GT3037/GT3076 “twins” have, giving the impression they would be damn effective and quite responsive power producers if you were targeting 450-500 hp. Whether the driver or driveline could cope with the results is a different issue.

Here is the link to Garrett: http://www.turbobygarrett.com/turbobygarre...bo_tech103.html Thanks Discopotato - it is very technical and takes a little digesting, but very good. Keep it going. Do you have an engineering background by chance? cheers

What are the highflow specs, and at what sort of boost did it record that power figure?

Ok, in the past few weeks/months there has been quite some discussion about the products available from Garrett, and I have to say it sparked my interest in learning more about the science of matching them, and then the practicalities of fitting them. The interest is in knowing how/why different configurations are offered by the manufacturers, and further variations by suppliers such as GCG and HP in a box. The mathmatical guide that Garrett gives is enlightening, and tells a whole lot about matching compressor flow to the power requirements of the engine. So far, so good. Where it unravels a bit for me is in getting an understanding of matching compressor to the turbine (ignoring the problems of the availability of T3 flanged units to bolt-up to Skylines). Running through the comments by many, it is clear that some units work quite well, while others are considered "laggy" and lacking a good mid-range (eg GT2540 on RB25) or having a boost transition point higher in the rev range than desirable. The concept of turbine acceleration and shaft torque sufficient to drive a given compressor was introduced, and this is what got me thinking... and confused at the same time. Turbine maps appear much simpler to read, and those that graph multiple A/R capabilities clearly show the ability of larger A/R to flow greater air mass at the same pressure ratio - thereby achieving higher levels of efficiency. Simple. The hard part is in matching and interpreting the capabilities of the turbine of driving the compressor, and knowing what sort of characteristics this will give. Obviously the experiences of others who have gone down that path helps, but how is it done? I'd considered that the pressure ratio calculated and superimposed onto the compressor map would be of some importance, but regardless of that, the mass flow capabilities of the compressor do not coincide with the turbine for any given unit. I am sure that if I delve back into my grade 12 physics and chemistry texts I can rediscover the science behind that one. What I would most like to know is how do you look at the two maps and logically reason how the two will combine. cheers

Yes, Discopotato, you are right. Later I thought my comment didn't read well. I asked whether the GT30 housing came as an unmachined or semi-finished blank that required finishing before fitting up. If that were the case (and doesn't seem to be), then the possibility could exist. How then, does Garrett get the 56.5mm wheel mated up to the internally gated housing that they call a GT30 that is evidently very different to the externally gated GT3076 with its 60mm wheel? I say "evidently very different" because of their vastly differing flow/efficiency maps and the obvious different method of turbine speed control. Do they both fall within the UHP family, and where is the information about that and NSIII? Hopefully I will get it soon... BTW I am going to kick off a thread about interpreting turbine maps just to keep the brain ticking over. cheers

Ah, this makes much more sense, and is something of a better explanantion of an earlier thread about the GT3071R and its variants. I will look at the suggested linked areas to become more conversant with the specs. I did speak again with the dealer today, and he was only aware of the availability of an internally gated GT30 housing, but it is not a regular stock item. Their stock catalogues were also at quite some variance with what is indicated as available on the TurbobyGarrett site, so making sense of what is actually available was difficult. Addressing the possibility of a "build your own" hybrid, I also asked about selecting a mix-match combination of a GT2871R using a 52 trim compressor, and fitting a GT30 housing. This does give the possibility of a spec the same as the HKS GT-RS (400ps), which incidentally has the same turbine assembly as the Garrett Discopotato (320ps) but the bigger 71mm compressor to generate the power capabilities. It ended up being a case of why try to recreate what is already available through a HKS dealer, and IF the GT30 housing can be machined to cater for the smaller wheel, costs aren't going to be favourable. Apologies for moving the thread off-track. cheers

Is there a reason why you have a spacer? Is the turbo physically too large to fit, or is there a difference in the flange pattern?