Dale FZ1

Kunda Park there is a Jap import place. Not cheap but they will probably have something. Alternatively Nambour Radiator Works may be able to sort something for you, depending on what's wrong with the original unit. Hope that helps

If in Brisbane you could also use Turbo Australia or MTQ.

Synchro assemblies are about $130-150 each. I've just had my box out and found the synchros were not worn out. The cone/ring assemblies were glazed and required bead blasting to de-glaze. Reassembled and using VMX80 it is like a new box. Very precise and just notchy enough to let you know exactly where things are. Very large single synchro on 1st, then doubles on 2, 3. If there is any apparent weak link, it will be the quality of change from 4th-5th, going on the synchro design there. FWIW, the internals look like they were designed to take lots more grunt than a stock RB25. There is even a factory-included internal trap door to prevent oil surging to the rear of the box under hard acceleration. Keeps the main gearset well lubricated.

I'm still backing that you will have the higher peak power numbers pretty much through the range but definitely up top. Transient on-road response might be another deal - your rotating assembly is bigger and physics should dictate it is slower to accelerate. Maybe Adrian can chime in with the impeller dimensions of your HKS T3/TO4S hybrid? I'd say that the turbine is the flow-limiting factor because your compressor should do more, and the cams are a help with efficiency. I'm interested to see the results of your dyno battle, but more interested to hear what happens in back to back driving. Maybe the Pro-S should give good light-throttle driveability, whereas yours would need to be driven more on the throttle to get it moving? I'd be even more interested again to hear what happens if you could also run it up against a 3071, split pulse or not. That would add an extra background dimension to whatever Full-Race Geoff comes up with.

It's likely that the major manufacturers DO have them under development, if not production. The info is out there if you do a bit of searching. But it is worth putting into another thread that deals with VNT.

Unless my understanding of the narrow-band O2 sensor is wrong, it is for closed loop feedback. ie. cruise conditions. Unlikely that will have any impact on crappy fuel consumption if you are only doing 2-3km short run driving. Cold start / low temp enrichment comes from the engine temp sensor feedback into the ECU. Yeah, you could alter the signal if you're savvy with electronics but it would likely run like a dog until warm. I suggest you plan a weekend away, and just do some cruising. Steady speeds, off boost, and actually LOG your fuel usage from full tank back to full tank. Then see what results you have over 5-600km. Many people don't know how to drive to achieve great economy, and FWIW, you don't have a vehicle designed to achieve it either.

Visual inspection of coils MAY NOT show any obvious problems, other than soot/carbon/grime buildup that would lead to tracking. Try wrapping them with insulation tape. Otherwise you could be experiencing the rich + retard syndrome. My R33 did, with nothing more than a 3 inch exhaust + pod + FMIC. No boost changes. Stock ECU said the mass-flow was too much and did something about it. Symptoms were much the same - ran fine down low, hesitating btwn 4600-5400 and then picked its act up and went much harder to redline. Sounds like you have the correct heat range and gap for the spark plugs. Doesn't matter much whether they're copper, platinum or iridium. That just impacts cost and plug service life. You could try to swap in a different stock ECU to compare, if any mates have similar vehicle.

Sitting on 11.5:1 at higher rpm, with a progressive ramping down there from the lower rpm scale. I wouldn't want to see it look any different to that shape graph. With a stock ECU you're not likely to see it any leaner than that up high either.

Gurus live on mountain tops. I live somewhere just above a wet gully... Still on for a yarn anytime though. I agree, basically the stumbling block is that ceramic rotor. Get rid of that, and things open up a bit. Those couple of options nominated really are pretty effective, as are the custom offerings from Slide and GCG. So in the end, he has a high flow.

Heaps of different specs being bandied about in this thread. The HKS GT2835 range uses a couple of different trim specs in the 56.5mm turbine rotor with the 71mm GT35 compressor: http://translate.google.com/translate?hl=e...hl%3Den%26lr%3D http://www.j-w-racing.co.uk/acatalog/GT_Ba...bochargers.html From memory I think BHDave is running a TA series unit which has little in common with the GT series gear. Still like old Grandad's axe with an edge on it though - it'll take your foot off as good as a sharp new one. The GT30 series units run a 60mm rotor, while those TD06, HY35, and GT35 units are all around 65mm (give or take). The couple of comp housing options mentioned by Adrian are just that - options. My understanding is their physical size and shape does impact on mass flow capacity and boost response to a degree, but not to the extent of the turbine housing. I'd taken the units to be tested by Full Race Geoff will be the 60mm based GT3071, using a conventional housing, and the split pulse housing.

The dyno comparison is handy, and quantifies numbers. Gives something to predict comparative performance. The drag race tells a fair bit about full load performance but little about daily driven capability. For me, the tell-all is in something like a hill climb event and/or a sprint event. Something where the max figures on a dyno sheet aren't the most important, but where response and torque delivery from low to full load become significant. After all, that is what this whole split pulse thread is about. For a GT3071, there'd be nothing wrong with a TO4B comp housing. More compact but not really lacking in flow capacity for the application. Less physical size might give fewer clearance problems and a tad easier to plumb up.

Exact spec (trim, A/R) of the turbo will determine both maximum potential output, and the torque DELIVERY. That delivery will be a big factor in how the clutch lasts, but not as much as how the operator looks after it. Hammering it off the line, clutching it regularly to big smoky slides will see it die fairly quickly. FWIW, my 2871 based high flow running 13.5psi max and 225rwkW gave the stock clutch no problems transmitting the drive without slippage. Spec dependent again, at 1 bar SL1D1N should be looking to a maximum potential output range between 210 - 240rwkW. That would be beyond the stock fuel system's capacity. And that is how he should view the fuel system - as a SYSTEM. Pump, injectors, pressure regulator. Changing FPR might bump up the max fuel delivery, but probably run into issues elsewhere in the load/rev range. If the budget isn't there yet, I'd say stick with the 9psi actuator and tune the thing with the interceptor. 180-190rwkW should be the result. If the finances ARE available, get either a Nismo/Tomei drop in pump, a set of bigger injectors like either the S15 450cc units or 555cc Nismos, and most importantly a decent ECU. Then slip the 1 bar actuator in and get it tuned. Depending on the ECU, may be able to eliminate the AFM.

Seeing as there is a bit of interest around, with a little bit more searching obviously there’s a bit of discussion going on outside of SAU about split pulse. It’s good to see guys trying to get their heads around the concept and how it applies to cars other than Nissans. I reckon it’s a good thing that BMW mirror Nissan’s approach with I6 configuration, so those guys really use the same/similar techniques when chasing good forced induction performance. Check this out for discussion and pics: http://forums.bimmerforums.com/forum/showt...ght=split+pulse Given that MHI do produce split pulse housings, I figure that the Subaru focused discussion on MHI TD05 / TD06 is also worthwhile, given that there are other products than the Garrett units we seem to gravitate towards. Just helps to make a bit of sense when the MHI-based Trust units are commented upon. http://forums.nasioc.com/forums/archive/in.../t-1081261.html

Well I'd guess the pro S will make it up to around 265-270rwkW tops. Yours will be good for another 20 (duh!! knowing it has already cracked 288+) at max. Full load figures will be in your favour, but the transient response difference might be different. If all the theory works out, and Full-Race Geoff can give us some idea with back to back testing, I'd wonder if the split pulse system 3071 can bridge the (perceived) gap between the mid-range/top end surge of the 3076 and HKS offering. In some respects I think either a 48T or 52T T04S based GT30 unit offers a damn good compromise already. Perhaps that split pulse system with reduced turbine inlet pressure can show it the way for response and outright power? Either way, bring on some results Dave, and Geoff.

Or do some homework and slot in a suitable off the shelf Garrett cartridge. Depending on your preference, the GT2871 or GT2876 range can give very good results too.

Applause from the side-line. Yes, it will at least give us some idea of what happens under full load. Thank you for pursuing this one Adrian, thought the trail had gone cold...

Paul you would know better than many/most that all GT30s are not created equal. It covers a HUGE range of mass-flow and performance capabilities. Just because Ash achieved such a large figure doesn't follow that everyone will. The 0.50 comp cover tells us little about the compressor ASSEMBLY. What size impeller is this thing running? Off the shelf you can spec 71, 76 and 82mm, with a variety of trims and specs. And assuming that it has the 60mm turbine rotor, what A/R is the turbine housing? The only thing that is a certainty is that the specs of each side will determine the mass-flow throughput potential, and efficiency. But it will be the TUNE that determines ultimately what it makes

Here's a link that gives some idea of the different impeller sizes on the MHI/Trust turbos vs Garrett. http://www.900aero.com/main/tech_main_turbo.htm I think a lot of the MHI gear is fairly heavily turbine biased, so Trust use a bit of mix-n-match to chase quick response. Pity that they use the 3 bolt turbine inlet, because genuine MHI turbine housings in TD05 and TD06 are evidently a T3 flange.

I believe that is exactly the technology they introduced with the VQ25 engine series. Naturally aspirated compression is somewhere up around 11:1 and it's reputedly a pretty good bit of gear - for the power it is producing.

You could be right - I've maintained the "systems" view. It would surely be dependent on how the manifold/turbine work TOGETHER, rather than chasing some technical advantage in one component. If there is some design/specification/manufacturing aspect in one or the other that works against the other, or is not geared to meet the performance requirements (ie: response/power balance) of the vehicle then the good idea may come to nothing. They sure LOOK ok! Got a link? I can't find anything from them to suit an RB25 like that with a Google search. The idea of varying diameter as a function of length to maintain consistent pressure is not at all bad. I'd say hydraulic engineers working out specs for stormwater drains etc would probably play with this sort of stuff pretty regularly. Varying the cross sectional area would possibly affect the speed of the pressure wave exiting the exhaust port, and might keep the timing of the pulse at the critical junctions nice and even. BUT I'd think there is a heap of mathmatics and probably simulation work required to get it right, or risk a lot of wasted time and $$ in trial and error. I'd say yes, please ask Geoff to comment here. He's one bloke who's working with the design and should be listened to. I don't see any need to keep this thread as anything other than a discussion that we can LEARN from.

As per earlier info posted up, these things DO come with a T3 flange. My understanding is that depending on spec, the turbine outlet is VERY similar in appearance to the MHI TD-06 with a bolt-up flange (trying to relocate a pic I found), or with a 4 inch V band fitment. Couldn't agree more on making it cost effective, especially if someone was wanting to bolt up to a stock manifold. FWIW, even the GT30 IW Garrett requires a different dump flange, so as soon as you go away from a high-flow of stock housings, you need to spend to get that one right.

Electro-hydraulically actuated gearchanges aren’t part of the discussion guys, but provide a bit of interesting discussion. I’m interested in a road-car turbo setup that doesn’t require expensive gearbox or final drive ratio changes. The rationale was to explore the system as a whole, within a defined power range, and with budget in mind. We are pretty well versed on what is common upgrade product, and the idea was to see exactly what we could get for the money and the desired performance. If discussion/experience showed that the stock manifold is a workable compromise, then good. If not, then that works against the cost factor. We really had to discuss at some level the dynamics of exhaust pulsing just to establish a platform. Whether everyone’s able to visualize the process is anyone’s guess but worth a go. I would suspect that the stock manifold is technically compromised, but workable in practice – within the defined power output as discopotato03 has said. I happen to believe that the power level is a key aspect to that point, because it’d be possible to live with the compromise where the discussion is focused, but probably not if you were aiming for (arbitrarily) 400rwkW or more. That is some pretty serious power, and having all systems working TOGETHER in a complementary manner becomes increasingly important. Laws of diminishing returns do apply. As Adriano has said – have a look at the MHI TDO5 units being used on the Evo from the ‘90s to current. They are current spec split pulse. To me it is significant that there is technology sharing between MHI and Holset, and that’s why I’ve been musing about both their products, and what is being used in service. I’ll back it in that Cummins (which owns Holset) is NOT putting dinosaur spec turbos on its engines. Check the compressor map for a HX30E Holset – very comparable to a GT37 Garrett in terms of size and maximum flow capacity. My opinion is that the HX30 will easily feed a petrol engine with 480hp or more worth of air. Basic specs search points to it having an impeller of around 76mm, and with 8 blades. Whether it proves to have a sudden delivery when applied to a small capacity petrol engine is another matter, but evidently they produce different trim sizes and impeller designs. No doubt they can be specified to better match the application. Can you add constructively to the discussion URAS, especially with respect to split pulse? This is not a wind-up. I do agree that impeller size and trim is a big consideration. With that amount of money spent, I want to hear what back to back split pulse vs single scroll experience you’ve had, and outline why split pulse just wasn’t worth it. Again: NOT A WIND-UP. If you’ve been and done it, then share the experiences please, not just your conclusion. I'm interested in the story.

Check the rationale for the thread. As stated, I'm very satisfied with my particular setup. Not many of us are rocket scientists, though there is the odd claim to that qualification from time to time. I'm just interested to see what is out there and/or could be set up ECONOMICALLY to yield the benefits claimed for the system. Frankly, I'm not yet convinced that it can be done, but hey it's worth a look and a yarn. If something came up and someone with the $$ and motivation to try it, then we might all learn something more. For example, Mafia showed what could be achieved with a 3076, a mechanically stock RB25 and water/meth. Just a step sideways to try to take a step forwards.

Not a bad start, but what I REALLY want to see is the turbo/manifold combination. The idea was to see what Mitsubishi actually does with the manifold runner length etc, as there has been discussion about the whole pulsing / tuned length aspect. I haven't actually seen one, or a picture of one. Correct me if I'm wrong Adriano, but from what I've seen of typical truck manifolds with split pulse they tend to run the 2 x 3 cylinder branch approach, similar to the RB20/25 setup? Looks very industrial, but with their mass-flow requirements it must work well. The MHI fitments to the Fuso range of trucks is something I feel is worth investigating Adrian, particularly because they are more likely than many to be offered with split pulse + compressor combinations that are not too far out of the ballpark - and availability and technical information should be accessible to some extent. I'd say it is likely a TD05 and TD06 would be very likely fitments in the smaller 4-6 litre engines, and the split pulse housing a fairly common option. FWIW, the HX30 Holset model seems to be a reasonable starting point, IF that technical info can be obtained. Compressor flow range 45-50lb/hr, high efficiency up to PR 3.1, and turbine options available (IW, various A/R, and those titanium impellers). AND they have a T3 flange.

Don't get me wrong Paul. I know there are some pretty well sorted upgrades already out there. I have gone the Garrett-cored high flow myself, and satisfaction is about 95%, given the application of my Skyline. The thing is, we don't realistically know if something with the stated performance parameters CAN be found for a comparable price to the products that are popularly used. Adrian agitated for finding something that could fit up to an RB, so it's worth a look at least. I'm not arguing the toss on piping size. I just found the site useful to explain the dynamics of exhaust pulsing, and the impact on optimal manifold configuration. Yes, I've seen some posts by discopotato03 on other forums canvassing internally gated split pulse interest. I'd say it's equally worthwhile seeing what is out in the market already, and trying to establish whether it is worth a close look. Thanks for the info on those HKS cast manifolds, I've not seen one before. So they are basically an enhanced version of the factory manifold design? I don't think we know to what extent unequal runner lengths in each branch would upset the pulsing apple cart. Hopefully someone can unearth a bit more literature, or better still some pics of what a Mitsubishi Evo manifold/turbo setup looks like, or even that of a truck. Seeing what they do might be enlightening.