Dale FZ1

My other question relating to housings goes to Mafia: I know there was a fair bit of to-and-fro about what was going to be the right turbine A/R for your application. And you have actually tried the 0.63 and 0.82 on your RB25 before settling on the smaller one. Can you give comment about what felt the best match please?

I have a question for Lithium about the comparison between using old Ford-style housings and the new GT30 family housing. Firstly, the graph for the 0.63 EW setup shows a similar trend to the 0.82 IW, and the numbers aren't THAT much different. Admittedly, that was with the EW setup having boost running away to 20psi, while the IW setup has fairly good control with boost evidently dropping. All of which simply points to better design, more efficiency, etc. So from that standpoint the GT30 housing is obviously the right setup. Secondly, you'd commented that with the EW housings that the larger A/R introduced a certain amount of on-road lag which was beneficial in terms of progressive delivery which was preferable to you. Question: while the IW setup offers better boost control + more efficient flow leading to better scavenging with same power from less boost, is there any discernable difference between the EW 0.82 housing and the IW GT30 0.82 housing? I don't have any issues with the GT30 being the right housing, more trying to learn what the difference (if any) is through seat of the pants.

Congratulations on a good result. You sound very pleased with things. Interesting to hear any alternative views from Mafia who has run both 0.63 and 0.82 IW housings with the same turbo. You're the only bloke I've heard of who gave reasonable consideration to the Holset HX/HY range. I believe they could be a good thing if only there was SOME technical info available for them. With split pulse housings they should offer the characteristics that Discopotato03 wants. I still suspect though, that the cost:benefit equation is still stacked against a true split pulse system. Any further comment on that I will post in the appropriate thread that has been dormant for some time. That torque dip between 3700-4500rpm is interesting, and seems to afflict many mechanically stock RB25 engines to some degree. Did your tuner make any comment about it, or have any luck trying to improve it? Actually, your torque curve has something of a saw-tooth appearance - is there more work to do on the ignition mapping? Obviously there is no shortage of torque, but I'd be wanting to see a smoother delivery across the range. As a road car how do you find this setup? ie. is there sufficient low-load response, or do you feel as though it needs a bit of throttle to make things come alive and get that jet-engine feel?

Exedy cushioned button. Plenty of bite, not too grabby or shuddery. Price is very reasonable too. Re your parts: forged pistons and rods won't "make" more power. But they will make the engine more reliably able to withstand extra power/load over the long term. The extra grunt comes from mass air-flow throughput. So whatever you do with engine breathing (manifolding, porting, port matching, turbo spec and boost, inlet/exhaust, cams) and the quality of the tune that goes into your PFC will be what essentially dictates the power you'll make. Given what parts you've used, you should have the potential to hit or exceed 275rwkW. And 300 may not be that hard to hit either. In the normal matter of interest, can you post up the ID tag number off your turbo? There are many flavours of GT30, so it'd be interesting to know exactly what spec you have, including the housing A/R. Overall sounds like you're going to have a lot of fun.

Have you cleaned/adjusted the IAC? I would suggest doing it, regardless of whether the thing idles perfectly with the standard ECU in place. Remember your idle is governed by both the ECU settings and engine hardware.

I think he's running an RB25. Hydraulic lifters. Point noted on springs, though most punters seem to get away with OE springs if using Pon Cams.

Previous posts by Murat, and the comment about "all supporting mods" indicates he has a PFC. I'm suggesting it's in the spark mapping ie adjusting one or two specific cells in the map, not the base timing being adjusted by a degree or two Could be wrong but that's where I'd look if there is a concern/query about the shape of the graph

Two distinct dips but not shaky looking graph line. I'd suspect 1-2 degrees of timing taken out to address knock. A look at your ignition map will soon tell. The over 4000rpm results looks good, but what do you think about things under that engine speed? Looks a bit lazy to come on for you. This spec should be generally similar to The Mafia, and he's pulling 300kW out of 18psi + a much more linear looking curve throughout the range with the assistance of water/meth.

Checking your dyno sheet, it appears that they both make approximately the same/very similar torque (and therefore power) at 115km/h. Then the higher boosted 25 makes and holds a higher figure to generate the power recorded. Makes sense really, with power being a function of torque and rpm. Wait until this 30 gets fed a bigger mass (via boost) and hopefully gets some bump sticks that allow it to breathe more effectively. Even if rpm is governed to less than 7k, it will make some pretty good grunt. If the current peak power rpm @ ~5300 is anything of an indicator, the torque will be stupendous. What's the difference attributable to? Hasty setup and calibration by the operator, or some real difference in gearing ie. tyres, final drive or gear ratios? If it's a 32 chassis, is it still running a 25DE spec final drive? Some times it's very good to review the graphs using both engine and road speed. I have an old chart from my bike being dynoed through the gears, before/after final drive alterations. The amount of extra grunt hitting the road in any gear, at any sane speed was significant.

I think it's great. Let us know the outcome and any other issues you have to overcome. Is the external gate feed welded to the stock manifold? If so did that pose any great problems for whoever did it? Do you know what is the compression ratio and what pistons were used? Any porting work done? cheers

I'd suspect that a 2835 of that spec would be at the maximum of its capabilities, and that the suggested 3037 would just do it a lot easier with better turbine efficiency (read ability to flow the mass-volume required). I don't think I would use the GT28 based turbine if chasing up around 300rwkW, even if it was the HKS variety. In the end, the max flow number is one thing - but the delivery and response characteristics are another. At least there are options, but the story remains the same. Be sure of the required outcome and size accordingly. Back on thread, if you're chasing 450rwkW, then it's going to be a completely different situation. Adrian's suggestion about the RB26 top end and twin 2530s in the right spec is pretty good. And it is a proven combination with the advantage of solid lifters. For sustained rpm over 8000, the reliability of hydraulics would have to be suspect in my books. Nothing is ever absolute, just saying that for high rpm solids are better suited than hydraulics. Obviously Nissan's engineers thought so too. If punters are getting there with a GT35 then it should work for you too. There is some good information on bimmer forums too, with the advantage that they are turbocharging 6 cylinders of similar size/spec as the Nissan engine. Again, what works for them should work for you too.

Water pump, timing belt + idlers, crank + cam seals, various water hoses. From the viewpoint of ensuring absolute reliability in those areas - YES. Oil pump as a service issue though, I doubt it. Some of the parts aren't particularly cheap, but if you consider the time + labour factor involved once an engine is in the car, it is a smart option while the engine is sitting on the bench/workshop floor.

Little bit more info on this exhaust manifold please? ie. maker and price bracket? I like the angled windows machined into the comp cover. No doubt it will sound like an F1-11 on take off. The purple paint job looks funky but makes me think of the purple TellyTubby

Ask yourself "what use am I going to put the car to, and how much power/stress/revs does the engine have to deal with? And how frequently is it going to do it?" What you will need to do then becomes much clearer. Why go the crank/rods/pistons from a 26DETT if all you really (maybe??) need is slightly lower CR to reliably push in a bit more boost? As above it really depends what you are going to need. Lower CR could be achieved with 25DET spec pistons, forged or cast it's your choice. And you could retain the 25DE crank and rods. Alternatively you could run a water injection setup on the 25DE - search 300rwkW thread by The Mafia for some discussion on its benefits. One thing to note is that the 25DET short engine runs oil squirters under the pistons. Factory engineers put them there for a good reason. I don't believe the 25DE engine does, so there is a limitation. If you're in the trade, maybe you should consider head bolts, bearings for mains and big ends, and quality head gasket too? The top end oiling restrictor mod might be worth considering just to finish off. Keep us posted on your progress.

As posted. Because I want the numbers. And I'm interested.

Good. Please do. Interested to hear the results. While you're spannering, please check the ID tag and also post up the CHRA number, and the housing A/R for interest sake. cheers

Never mind the specs or numbers. What do you do with it, and how's it go? Not FI, but man you need to explain a bit more.

All copper washers to the banjos installed? You need one on either side of each banjo, and obviously everything should be nicely firmed up. There is plenty of opportunity for leaks unless you double check everything. 30 mins with a spanner should see everything sorted by the sounds of things.

Slow is relative. Now you've spent quite some time and still feel it is running weak at higher rpm and load, you should really have little problem buying 30mins of dyno time. It should provide some additional insight as to whether it really is running weak, or if you need to be reassessing what is slow or not.

Troy you seem to get very good results by basically sizing the turbo UP and running the engine in a higher rpm range than stock - correct? Over time there have been no shortage of comments about the RB20 and its ability to reliably cop 8000rpm. Basically if this is what it takes - to either hold or increase torque at higher rpm then you clearly get more power. The idea is nothing new and should work great (just don't expect much to happen under 3000 for argument-sake) provided your gearing allows the engine to perform at sane road speeds and make use of all gears. Taking that approach, using a larger turbo makes good sense. The owner should just be prepared to make vigourous use of the upper rpm range just like a Honda VTEC owner would.

Well nothing is a certainty - it could still be valve float. But there is an order of convention that he should run through to identify what the "problem" is. Otherwise there is a risk of just throwing money at it for no net return. What I can say is there is a total of 4 different cars nominated in this thread that are/were running a similar turbine configuration with Garrett/OE hybrids. They basically all found a limit somewhere around 230-240rwkW. I'm unaware of complaints about their rate of spool, but the common factor seems to be a ceiling on their mass flow capability - ie what maximum power they are able to support. It may be that the RB25 housing / 56.5mm turbine combination just hits a brick wall in terms of mass flow. Perhaps the GCG unit can extend that ceiling a bit further (but not much in the scheme of things). If there was an issue with mass-flow capability, the demon rising exhaust manifold pressure (aka back pressure, turbine efficiency) would be evident if you were able to fit a pressure gauge to that manifold. A genuine HKS housing may be just the ticket if he is chasing a particular max power level, but there is a cost factor involved. Dropping off the exhaust from the cat will merely prove/disprove whether exhaust restriction is a major factor and allow him to decide whether to pursue it further.

Specs sheet says the assembly # 700382-003 should equate to 71mm GT35 compressor family, 56T. 0.50A/R comp housing 56.5mm turbine, 84T. 0.63A/R GT25 turbine housing. Yes, it is a GT3071R, or its same product/different name alter-ego GT2835R. Obviously it is running a different turbine housing with T3 flange, since it's a bolt-up. Mafia's probably correct that it's an OE style housing, machined (or remanufactured, or high flowed - take your preference of term) to accept the Garrett assembly. While the GCG style high flows claim a capacity up to 250-260kW, their impeller specs are hugely different to this Garrett. A visual inspection and measure of the 4 impellers is very telling. GCG have got it pretty well sorted with their spec - and they have trialed at least a couple of versions to get things right. I believe Mafia is on the money with this one. Experiences with his own earlier hybrid, and from a Central Queensland SAU member who ran a GT3071/RB hybrid suggest that particular turbine combination might get another 10kW but bugger all more. And so we hit on the issue of "happy" dynos yet again. Your AFR shows fairly conservative figures around 11.5 - 11.7:1, and narrative on ignition timing signifies that it has been given as much as it will safely take. Realistically, not anything holding it back there. A boost curve overlay may help identify other potential problems - eg. either poor wastegate control or a system restriction. Definitely drop the exhaust off pre-cat and just see with a quick squirt on the dyno. That will take very little effort and avoid paying for something you may not need ie. another cat. A genuine HKS turbine housing - which is not easy to come by economically - might make it a very different proposition. The question to ask is: what does it go like on the street? And have you lined up against any other modded Skyline with similar goodies to see what's what? Take it to the sprints, drags or whatever gets you going, and go nuts. Then tell us. I will be most interested. cheers

You could have saved yourself a lot of running around by getting a mobile unit to come on-site. Best of all they will get the length and set of the lines correct. The risk of having the custom lines chafing or cracking from stress or vibration Leave the steel water line in place. Have it cut somewhere around where it emerges on the LHS rear of the head/block, and get the hose man to attach a fitting to it. Then have him make up a suitable line that marries up to the fitting and takes a banjo to fit onto the cartridge. A simple search could have revealed pics of the very job you want to do. That water line is virtually impossible to otherwise get to, and best accessed either when the engine is out of the car, or gearbox out to change a clutch.

You need the services of a hose specialist. Enzed, Pirtek or whoever suits you best. If you've used a Garrett cartridge into stock housings this is fairly normal. The OE fittings do not fit the Garrett cartridge, and you basically have to get them to do a little work to make it all come together. No big job actually, and something they can (and should) come and do on-site. There are some threads with photos available. Search under my name, and from memory Ol Mate also posted something regarding adapting oil/water lines in the past month, when there was a query about what people believed constituted a "bolt on" turbo upgrade. And yes, there are fittings that have barbed ends. I have a set still sitting in my shed that were not used, in preference to banjos that took braided line. cheers

If you have them please post up - the dyno sheet with boost curve overlaid - the ignition map - the CHRA number and housing A/R from the turbo you're running It can be hard to search for something if you're blindfolded or running with partial information only. cheers