Dale FZ1

Well put Gary Often in the discussion it's easy to forget that there are other uses and applications that these cars will be used for, than that which we prefer for our own cars. A well spec'd street engine may have shortcomings that show up in track/race use, and vice versa. It's hard to overlook the benefits of either E85 or a good WI system to keep these things away from knock.

It's not without a tinge of humour that I read your findings are similar to the advice of what to expect out of that 3076. Cams, porting and valves wouldn't have made half the difference that the dump and exhaust system did. Perhaps time to update your thread on that topic.

None of the previous post should be interpreted that I am pooh-poohing the x67. It could and probably should make for a responsive, streetable little weapon but why worry if it can make a hp number around 400 on a sheet. If it responds quickly and gives strong easy torque in the rpm range most frequently used/accessed then it could be well up on the list of choices for those not wanting to spend up on bulk modifications and upgrades.

Possibly missing the point Adrian. I was thinking that perhaps the GT28 spec turbine just wasn't up to the flow capabilities of the compressor even in with the 52T 71mm compressor on the GT-RS. The fact you could whack 17psi through it in the mid range and then it tailed off to 14psi up top is something of a telltale on what its strength was - light/moderate upgrade from stock. Blow too hard and you could (did) find its limits. Back it in that the GTRS on pump 98 was somewhere in the 240-250rwkW bracket, and you'd generally need everything matched nicely to get the last 10kW. The flow map for this X67 compressor combination is not that different vs the GT2871 52T if you run in the 2.0-2.5 PR bracket in terms of what it will pump, and efficiencies. But it can be mated to a turbine with greater flow efficiency. I'll consider this unit a good option for those considering the HKS product, but not that far removed in terms of overall characteristics. Garrett themselves never went to the trouble/expense of developing a T3 flanged housing for the GT28 turbine so that's telling us something. Steve the OP nailed it in saying that running this thing out to maximum rotating speed simply wears it out faster, when the option is to go up a size in compressor if you want to knock on the door of 300rwkW. Difficult to justify the logic in screwing the heart out of a turbo although there are those who do. Short service life = more frequent bills to change bits out, and not too many people have a sponsor or wealthy uncle It really comes down to identifying the desired outcome and specify accordingly.

I'm with Mick on this one. That 3067 looks very much like a newer/updated iteration on the 2871 GTRS concept. If it's run within certain limits should prove to be quite responsive and make a solid spread of torque. Looking at the flow map it's hard to conceive why on an RB25 you'd want to screw much any more than a PR of 2.2-2.3 out of it when big brother GTX3071 exists. I'll back it in that the claims of 400whp etc cited by Adrian are with US based forums and there is endless conjecture about the difference in the size of their horses vs Australian ones. The Yankee brothers always seem to claim more. This little unit just appears to offer a decent output and possibly better low rpm/load response but why you'd want to buy one if targeting beyond the 350rwhp (Australian sized ones) would be baffling.

Very much a niche turbo but it might be ok and fill some people's objectives.

You'd really want to acquire the RB26 crank/rods as surplus throw-aways for next to nothing before you'd bother with the time/expense of fitting the things. A piddling few cc would hardly be worth it. Overboring the RB25 block will pull a few more cc, but are replacement pistons readily available in +1.5mm / .060"? Understood that it's off topic but if you want cubic capacity then the dirty 30 is the most practical solution although that raises issues for legal compliance for some. Without either E85 or a good WI system you couldn't contemplate knocking together an engine with high (and 9.5:1 on an old tech forced induction motor IS high IMO) static CR because it simply won't take decent full load timing or much boost without wanting to knock. If it must be a 25, Gary's thoughts aren't bad. Possibly a very good/practical way to view this topic is to nominate a budget eg $5000 and see what you can realistically knock together. Someone who can do it for 4k will be in front with a years registration or a set of tyres - that's the juggling act we all have to perform.

There are varying ideas about the value of fabricated manifolds, and your choice might be influenced by application the car is being used for, and budget. The stock manifold will easily flow the sort of exhaust mass at the target output, but Roy has very specific experience about what the drive characteristics can be when changing from fabricated to OEM cast manifolds and vice-versa. Perhaps search or PM and solicit his views directly. IF you chose the 3067, you may find a half decent compromise (financial and performance) to be sourcing a Kinugawa 0.63 housing and graft the Turbosmart gate directly to that. Might yield very quick response and proper boost control which the GT30 0.63IW housing does not seem to have a good reputation for. Probably have an easier time of fabricating dump pipes too. Then you always have the option of going up to a fabricated manifold at a later time. Be aware that the GTX3071 will punch harder, and don't short change yourself if you harbour a desire to run 20+psi through the smaller unit.

You won't find the results vary much whether it is a Neo spec engine, or R33 spec RB25. There are no commonly known results for the GTX3067 so you would be breaking a bit of new ground there. Power target does not look terribly high with the quoted PR and mass flow targets so it may well be a half reasonable match. The turbine will surely have enough capacity to exhale what the compressor is trying to pump through it. There is another thread with comments about this unit. For GTX3071 check out the results achieved by Mick-o

Holset seem to get more attention on US based forums. Perhaps their availability there is greater. Pretty sure the HX35 model name will cover a very wide range of units of different specification.

Haha that happened to me just before scrutineering once. Pulling it off (as in removing) looked like it was being pulled off. Lots of laughs. I think Wolverine's point is clear. As a whole package, Mick's 33 powertrain was difficult to fault. That would include the E85 fuel system as a complement to the turbo system. Compact, almost stock looking, and so damn savage when given the boot, yet quiet and unassuming when not. The only thing I would think likely to improve that particular combination would have been a RB30 bottom end purely for the off-idle and off-boost torque but that's off on a tangent. That RB25 was a damn good combination that can be readily bought/built up because the bits are not rare. It's not like the OEM cast manifold couldn't flow enough to make the numbers, or as if it was not driveable. A half competent bloke could probably make further small gains with a die grinder smoothing the sharp bumps in the primaries but it's hardly essential.

There is no doubting the benefit of experience, and having the correct/best tools for the job. Sometimes that includes having one particular spanner modified to get to that one particular fastener. Running a HKS Pro S IW housing with a custom dump pipe, I frequently found that one turbine flange nut, and two dump flange nuts gave grief during fitup. Generally, having a second set of hands around proved a bonus for this novice. But it still takes time and causes strain on the lower back while leaning into/over the engine bay. The cast manifold was never a real issue to fit/remove because nothing was hanging off it and access was good. Going over things for pre-event spanner checks while everything is fitted up is the time consuming PITA that I commented about. Not much point leaving 2 or 3 because they're difficult and patience runs thin. I never had any complaint about how that setup actually performed. Retaining stock heat shielding was another bonus and cost saver. Perhaps the OP might verbalise what application his car is being used for.

So I see... Those pics posted up by Callan look like a pretty setup, but don't appear to improve serviceability. Low mount fabricated manifold is difficult to give a rational thumbs up. If it's just for appearance or to satisfy a personal whim then good luck to the OP. If the aim is to get honest, experience based opinion for low mount and low key appearance then I would follow Mick-o's lead.

There's no easy or right or wrong answer to the OP's question. The idea of keeping with the OEM RB25 cast manifold has some benefits, particularly with road-only use where the whole setup never really gets the sort of thermal belting that happens with a race-only setup. Nobody can claim that the OEM manifold makes for an easy or quick process of checking for tight fasteners or (worse) removing the turbo. Normal people couldn't afford the cost associated with paying for a decent mechanic's time. I grew sick of the difficulties of getting a spanner onto all the fasteners around the manifold and turbo. Trying out the high mount setup at least makes the process of spanner checking all those points much simpler. And that is the rub for me - I accept Scott's comments about the ability to make power with the right bits attached. But does the ability to check and maintain things count for the OP? I accept Troy's comments about delivery. Does that count for the OP? Not many things come for free, but if some outcomes are high priority, it can become money well spent.

Contact hardsteppa - he has a TDO5-18G internal gated. Might give a useful indicator

So the indicators are that people are using them on smaller capacity engines requiring higher PR to make the grunt and benefiting from a more flow-efficient turbine. Perhaps a candidate for a RB20 tragic

Reed valves still count. Stand corrected on this gear hitting series production units. I have a suspicion it (or something similar) was also seen on Evinrude outboards

Direct injection 2 stroke as trialed by the Sarich Orbital group. That would only have one set of valves. Supercharged for scavenging purposes. At least that makes it eligible for the Forced Induction section. All pie in the sky stuff.

Don't replace heater hoses. Ditch the heater. Definitely no future leaks. Dan J - why not ditch the bonnet catch. It will need 2 fastenings, pins will do the job nicely and remove surplus sheet metal that impedes airflow to the radiator. Less can be more, even if it means a bit more work. Ben - agreed. This thread belongs in Motorsport Builds though.

Ditch the bonnet catch assembly. Use bonnet pins.

Best off giving the job to a competent auto electrician. If it's a track car consider why you would want an accessories position. Surely you don't have a radio installed...

A set of suitable valve springs will hardly break the bank.

hy-rpm what does it drive like with the 0.86 housing? Full load graphs tell one aspect but how does it come into boost and does it have enough when not full throttle?

Broadly speaking, I suspect the factory had emissions/economy targets to reach, and their design brief required smooth usable torque from 1500-4500rpm. VCT plays a big role in hitting those marks. Someone chasing 500rwhp has targets that don't really include emissions or economy, and the engine is likely to spin between 4500-8000 depending on cubic capacity. Strong low rpm torque may not be a high priority and lets face it between 3-4000 an RB25 or 30 in the 500rwhp range will be making significantly more mumbo than most. Would you notice the lack of VCT in that area? Probably. Would it be a big loss? Probably depends on how frequently you actually access the potential. For a 100% race use I'd think a well matched fixed cam, properly dialled in would be viable and remove one layer of complexity. For 100% road use and with a set of VCT cams it would be hard to think why you would ditch them other than to have a play.

8.9mm is about the limit before you would need to lift the head and have it machined for clearance if you went for higher lift. You will find that the likes of Kelford, Camtech, and Tighe can supply fixed cam profile that's compatible with hydraulic lifters.