Dale FZ1

For the coin involved, this is a very good turn-key option. People comment about how thirsty those things are, but the difference in purchase price will have you driving for years - and in a much newer machine. Still I like the fact a Tojo runs full time 4WD.

N/A 100 series diesel run the same powertrain. They do feel dead. But they're capable of barrelling along quite well on the flats. It's just hills that slow them up. You are likely to have a GCM of at least 4.5t when towing a Skyline on a tandem trailer. Provided that basic engine health is good, it will be a good platform for turbocharging and tackling those hills a gear or two higher, as per comments from others.

It all depends on the basic health of the engine. Poorly serviced/maintained and trying to extract massive amounts of power gain over stock will result in a short life. Approaching 300k you'd have to give it a good checkover before either buying the thing, or committing to turbocharging it. Reputable installers seem to target gains of about 40-50% over std, with a close eye on exhaust gas temps. Within those parameters the 1HZ seems to be happy and provide good service.

Great pic - oddly I was following your times against this very car until they struck problems.

I understand better now, thanks. It's good to see things posted in here, definitely provides broad comparison for Mitsu and Mitsu-based turbos. I can recall some pics you posted up some time ago of the TDO6 turbine - quite a "flat" blade form that looked pretty restrictive to passing gases? Presumably by going from 12 down to 11 blade its flow capacity will have been increased, though it might take a few more rpm to get moving. Reduced wheel mass will give lower inertia and hopefully even up most of the difference The SL2 and H4 turbine blade shape/forms appear broadly similar, much more "open" than "flat" at the discharge zone. They both look like they should pass gases pretty easily and offer good flow efficiency. How efficient they are in drive and spooling the compressor is going to be interesting for sure. Good luck , hopefully the 73HTA spec will do what you want of it. I tend to agree that the turbine housing will be the crucial factor in getting the best match to your big-bore RB25...

Troy did you use the H4 turbine rotor with this RB25 + TD06-20G 12cm combo? From those comments it appears you have? Comments are a bit too cryptic to decipher, and remember this is a Kando/Kinugawa thread if you are using a custom build. Sounds like impressions are that it currently delivers in a progressive manner, and winding some ignition advance into the thing will help that particular setup with regards to spool and bottom end torque. If I'm correctly interpreting your specs to be tested, I reckon the T67-25G will come on easier.earlier but then perform roughly the same across 4000-6000ish. Bigger turbine flow in the TDO6-20G will help scavenging up towards the 7000 mark but then your comp flow seems to be the limiting factor and not much expectation that it can exceed 310rwkW. The T67 runners seem to be able to push things up towards the mid 340 mark via more boost. Is the target driveability? If your R32 is seeing mostly/only track use then "best" turbine flow will certainly help the engine. Maybe stick a set of Albins 1-2-3 gears into that RB20 box and keep things spinning in the happy rpm range. Feed us some more information please.

On a 25DET that setup should be a pretty good thing, depending on the manifold and gate. Wait and see what Troy comes back with in terms of results

A 12 cm housing and what turbo?

I'll take a punt and say that the 25 won't wake up down low with the bigger housing, but should shade the 20 between 4-7000. Will be an interesting comparison.

Noel is right. This is the setup to use for streetable torque. Getting approval in NSW might be the stumbling block if time and effort is factored in.

That always seems to be the perennial bugbear of Pommy engineering - some good ideas, poorly executed in terms on maintenance/servicing or reliability. Little wonder that Rover were happy to get Honda on board back in the day.

What a shame. Should have built a Cobra for a fraction of the cost and use it as an open top pose machine. That thing should be welcomed into any historic type events and run at speed. I love looking at the vision of Rob Sharrad's Sauber C9(?) Group C.

You're teasing with this one. Is it a replica because it wasn't made in Weissach? Or is it a modern reproduction that follows the original plans and never raced? It seems that numerous builds of the 956/962 were not carried out by Porsche themselves. Reading up on their history, comments by Derek Bell indicated they were very "truck-like" but that toughness was what led to success in 24 hour events. Ground effects that worked was the obvious big advance from their 935 model. Tell us a little more about this thing.

Mark, your sig indicates you are in Queensland. Low mount, high mount, its all legal. No good asking people based in Vic or NSW. Regardless of whether its a HKS, 6boost, or a stocker with internal flow improvements, they are all going to make the engine exhale more easily. The flow efficiency can allow it to make more power, respond just that little bit easier, or use a little bit less fuel in general use. Sometimes its going to be difficult to say X manifold will result in Y kW gain, and the cost:benefit analysis is hard to make. It's not that hard to conclude though, that if your setup is spec'd and tuned to run around 300rwkW and not much more, then you could find yourself spending 500-1500 for a gain of 10kW. That's not a good return on investment at the top end of the scale. On the upside, there have been users posting up comments indicating that the gain in response and feel/driveability do not show up on dyno sheets.

Triple Webers with K&Ns Dellortos will make the grade too, basically a copy of Webers. Much better result all round - have a close look at what the classic/tarmac rally guys running L series engines in early Z cars do and it might add some weight to the comments above..

^+1 If you have the tools, the time, and the inclination then I'd say there is nothing to be lost by tidying the gas flow path in the OEM manifold. The runners can be made a lot nicer, and port matching is always going to help things. I reckon the collector/merge area is not the nicest aspect of design from a flow standpoint although some judicious work with the die grinder should bring some improvement too. If you're doing the work yourself, look at the potential to pick up 10-15kW (tops) for free. Bottom line is that if you were paying workshop rates to get it all done to optimal levels, you have blown a proportion of the cost of a decent fabricated manifold that has a decent gas flow path and collector already. If you happened to have a cast HKS manifold sitting in the shelves however, you would be putting it to use without thinking twice.

Ditch the nudge bar and single carb. Fit a set of triple Webers, some flares and an LSD and you're pretty much there Kameari.com have a large array of stuff available for the L series gear

It's all about the flares and the Fat Lady singing in the forest. http://www.youtube.com/watch?v=SR79FHm6c6Q

Seems you are in the US or Canada? Is the Castrol GTX you refer to a full synthetic, or mineral base with synthetic fortifiers? Suggest a change in oil spec, use the mineral base oil, and go to a 10W60. I'd think the piston rings are not yet bedded properly (particularly if chrome rings are used), and it shows as blow-by when you flog it at an event. You just can't run the engine hard enough/long enough on the road for it to show up. As per other posts, bigger vent lines to the can, and oil feed restrictors to the head somewhere around 1.3-1.5mm would be a great help. The catch can looks a tad small, but change/modify it to take a second breather filter. If the cross-sectional area on the filter necks is larger than the breather lines from cam covers then you reduce tendency for a venturi effect that can drag oily vapours straight out through the filters. Bottom line is change a few things and persevere.

Yep, it is interesting - thumbs up for backing yourself and having a go. I hope it is a good thing.

No disrespect to you Scott, if you are doing the work for him. I'm aware of the dimensions of the scrolls, and the likely/available pipe sizes that would be employed if modifying a "free floating" type housing to take external gates, and don't see that as a particularly viable option. There's not a lot of cross-sectional area in each scroll at the likely point you'd cut in, versus the size of pipe you'd be using to feed the wastegates. That said, I am not a fabricator - perhaps you'd modify the manifold? Disco seems to get the thrust of my comments - at that 300kW mark the best bet from a cost:benefit standpoint is to run with an internally gated, bolt-on setup. Anything else means spending time and real $$ to get it set up right. I do feel that an external gate setup IS better because - provided the design is a good one - better/more flexible boost control is possible. That is why in some earier discussion about Disco's options I indicated knowledge of two members who had difficulty running less than 19psi from a 0.63IW GT30. My position is as steady now as in '07 - practical and cost efficient setups should rule. Manufacturers are knocking out some pretty cool gear these days, and there are undoubted benefits to split pulse (Evo, Mini) and compound turbochargers (BMW, VW) - but I don't see great need to go there. The question was posed about split pulse, and the intent was to point out complexity and expense (whether IW or EW) in going that path simply to achieve bragging rights of technical superiority. I wouldn't push anyone down the path of an expensive split pulse setup, but if they feel compelled to do it that way, it should be done properly - as you point out that is an expensive modification path. I'd rather see the extra funds diverted into making sure the grunt can be put to the ground - diff/tyres/suspension. People mention 300kW like it's nothing amazing. In my view, achieving that figure on an RB25 is relatively straightforward and thare are a good range of options to get there. Being able to do something with it is a whole 'nother subject.

The only thing that jumps out at me regarding the GTX series is that they outperform the older GT series in terms of mass flow at higher pressure ratios. Whether they outperform them when compared on an equal footing (ie spec with similar potential mass flow) and see if they can out-spool the older-tech units is the issue. For that reason I have indicated that the 52T GT3076 will be a good unit, with good spool, and able to touch the 300kW mark especially with the head and cam changes, plus ethanol fuel. On a RB25 we can confidently predict it will take 18-20psi, and at that level the GTX3071 is likely to be very similar in character. The much-discussed smaller-trim turbine might give that earlier/faster response, but at this stage that isn't happening. Split pulse, and/or fabricated tubular manifold might also give earlier/faster response, subject to budget and/or desire to keep things looking stock-ish.

I'd suggest you try to have a look at the two housing types, say a GT30 0.82 split pulse, and a GT30 0.82 single scroll. Make sure you have an engineers ruler, and or a set of verniers, and even get hold of a couple of small thick wall pipe sections in the size you think you'll need. Do some research on what size steam pipe bends are available because that's what your fabricator will need to work with. Then after you've measured the size of the scroll where he will be cutting into, try to imagine how that can be married up to the pipe section. And be prepared to explain to your fabricator how he will do it - because the sizes are such that I'm pretty sure he won't see it as achieveable. Single scroll will be a different situation - they can, and they do fit EW setups onto the housing. There are those who swear by them. That sort of setup must work, but it's got to be limiting if you ever want to try a different spec (even just an A/R change in housing for your existing turbo). So for a split pulse GT30 onto RB engine, your realistic current options are 1. Get a fabricated manifold to suit the Evo spec IW housing. Bonus is that there are two housing sizes available. Run with a 6Boob, ETM, or even the Kiwi-made Hybrid manifold. 2. Get a fabricated manifold to suit an EW setup. Ideally there should be two gates, and you're going to have fun fitting all the exhaust plumbing into a limited space. Best bet for this one is find who supplies this setup already done, otherwise you're paying workshop rates for someone to figure it all out. My post on GTX3067, GT3071, GTX3071 and GT3076 is conjecture based on some real life experience, and reading/interpreting published data from the manufacturer. There is nobody who has come on board and stated they are using the GTX3067, so the actual spool characteristics are unknown until someone tries one out and tells us about it. My view has already been stated - don't expect it to outperform any of the other models down low on an RB25. Perhaps on a smaller engine eg SR20, 4G63 Evo and running 1.5 bar+ boost, they could be a good thing - we just don't know. But have a look at Garrett's literature, and see what they are recommending/suggesting should be fitted to that Evo spec housing. What gap are you trying to bridge? The flow maps are published, and the manufacturer says the bigger 71mm outflows the smaller 67mm, so it will be outpunched up higher for sure - all other factors being equal. If you went down the road of a split pulse setup for response, theory says the smaller 67 should get going easier, but it's GOT to spin up another 10000rpm or so higher to do its thing compared to the bigger unit. That's got to take time that the bigger compressor is already using to its advantage. If you are motivated to go the route of a GTX3067 in split pulse then please do. It should knock on the door of 280kw, and perform very good also. I would be very interested to hear and see the results if you want to show it off - plenty of good venues and events around Brisbane eg. Mt Cotton, Norwell, QR, Lakeside.

Garrett literature rates the 56T GT3076 at 525hp, so the 52T version would be a safe bet around 480-500hp That said, the GTX3067 vs GT3071 56T are rated at different (potential) hp despite the flow maps topping at the same sort of air mass capability. Good example of technical specs making a liar of the marketing blurb, since most people will only look at the quoted figure. The most telling figure is the speed ranges for the various compressor sizes ie. GTX67mm, GT71mm, GTX71mm, and GT76mm. Each time you go up a size in OD (exducer), the compressor can pump the same mass for lower rotational speeds. I think that is Adrian is acknowledging in a roundabout way by commenting on tip speed. So for a given turbine spec, the "old school" GT76mm is just going to get going earlier. Until I see/experience turbocharger speed datalogging, I would be doubtful that the smaller compressor units "windmill" at significantly different speeds (if at all) than the bigger unit and therefore they have a bigger rpm delta to bridge before doing the business. Smaller diameter, lighter mass, and presumably improved aero might reduce the gap, but as I see it the GT76mm compressor is no slouch in either 52 or 56T sizing. I also acknowledge that their likely efficiency/capability is not as good at high PR as the more modern GTX design - hence why Mick-o could knock out very (very) good results with the GTX3071 on a stock manifold, high-ish boost and E85. But it takes the higher boost levels to show that improvement. It's a case of understanding the spec of the combination to get the best out of it. I'll bet that Mick could safely achieve another 20-25rwhp and maybe improved spool simply by a change to decent fabricated manifold and EW, but the results vs $$ spent may not justify it. The rider on all of this is that the GT30 runs only a single spec turbine rotor. I get Disco's commentary in his TR30 thread regarding turbine trim - perhaps the GTX compressors would make a lot more sense with a different trim/aero capable turbine unit but that is all we have commercially available - IF you want to stick with Honeywell product. I'm interested in comments regarding the HTA compressor units - with some thinking and product planning that is not corporate Honeywell there might be some useful gains while sticking with the GT30 turbine. But I'm also interested to see at what extra cost.

Split pulse aka "twin scroll" is relevant and useful in all cases. The difficulty is in doing it right. There are other threads that deal with this topic. The answer to your question IMO, is no. You would have to perform a bit of miracle fabrication work to graft in the wastegating for split pulse onto a stock manifold. Go to fullrace.com for a look at how they do things, and price up the job. It is the technically best way of doing things, and the results should be discernably better, but there is a cost factor. I think there are a lot of Skyline owners quite happy with the results of conventional (ie single scroll) setups running single turbocharger. The best current bet would be to find someone who can/will make a manifold to suit the Evo-spec GT30 split pulse IW turbine housing, and run one that way - dependent on cost comparison with the Full Race type setup.