Dale FZ1

The Garrett style housing does not necessitate a shellback style dump, whereas the HKS one does. Doing either a divorced pipe off the turbine, or a bellmouth for that Garrett housing would be relatively simple. I've only seen one other example of that HKS style, and it came from HKS. Jonno do you have any pics of your inlet pipe to post up? Also interested to know if yours suffers from any stalling issues?

Engine-wise the biggest hurdle Adam has is the model – it’s a GTS4. Things I see as negatives with that spec engine are 1. conrods 2. unknown piston suitability at the targeted power output 3.lack of under piston cooling oil jets 4.cam spec. Doing something with the bottom end is similar to any GTR going to RB30 from a fitup viewpoint. That would mean an adaptor kit, so not all bad. The extra grunt from +500cc would be very attractive, and CR is forced aspiration friendly. A Stagea spec RB25 bottom end should be readily available (cheapish), with rods similar to RB26 (beefier), and oil squirters as stock. I view the squirters as a very important part of the high-comp equation, as they can keep temps out of the pistons – reducing knock tendencies and chance of pistons nipping up tight in the bores. And it would bolt in. Optimising cam profile would take a bit of homework, and as per comments in Adam’s TD06 thread, obtaining/maintaining effective scavenging would have to be one of the critical aspects of having this high comp engine run and make the power target without detonation. Measurements and exact specs are not known to me, but if 25DE cams run slightly wider overlap than a DET, it for forced aspiration could be a good thing for torque production across the range (with a negative for fuel consumption). Drop in some DET cams (cheap) and it would be an interesting back to back comparison. There is no argument that the 0.63 turbine housing will increasingly be a restriction as the engine revs harder / makes more power / has greater mass-flow throughput. In some respects the issue of whether it is detrimental to the match with a 25DE is trial and error. Going by Mafia’s experience, he hits 19psi @ 3200rpm. An engine will be most knock sensitive when making peak torque due to that being when the most work is done. With this 25DE+T I’d see the rpm range between 3200 – 5000 as where it’d be most knock sensitive. Here’s where I have a slightly different view to Adrian in that across that critical range the wastegate is open, and venting excess gas flow to control turbine speed. At the same time, it is clearly dropping the turbine inlet pressure and tending to aid the all important scavenging. The rider to making all this work for me would have to be manifold design and wastegate size + placement. I wouldn’t be confident that there is sufficient room in a low mounted position to weld a vent tube direct onto the turbine housing and still achieve a free flowing result. For that reason I’d go straight towards a decent collector style manifold with provision for EW venting before the turbine. I think the EW 0.63 GT30 can work well on the 25DE+T, but getting the detail right is going to be super important if it’s going to make the power and live. The ignition mapping is going to tell a similar story as measuring pressures in the exhaust manifold ie. just how well it works in practice.

Given the application of a high comp 10:1 25DE bottom end, and the choice of a 3076 cartridge, I'd have swayed towards the split pulse if the budget would stretch. The cost of a properly made split pulse manifold + external gate on top of the turbo would certainly make for an expensive fitup though With regards the GT35 to 30DET match (a bit OT, I thought??), I've been for a run in a fairly serious Toyota IS300 running a 2JZ 3.4 Jun stroker kit with GT35. Not directly comparable to the 30DET, but extremely progressive, and it evidently took away the bottom end savagery + allowed about another 80hp to the max output. Balance that against the results Al achieved with his 30DET + 3076, and I think that whether to run a GT30 or GT35 on a 30DET would probably come down to application (road or track/strip), and how much money has been spent on the RB30 rotating assembly - ie is it configured to rev reliably? On subject, the 0.63 + EW should make decent power + response as WYTSKY wanted. I'd be interested in the results, and also to see the ignition map once it's tuned.

If that turbine spec was available with T3 flange, you couldn't overlook it. Even better if the neck was long enough to remove any need for a spacer when mounting up to a stock manifold.

I'm guessing the GT3037S-56T on the tag led to that comment. Mine also has that tag, it's just what Honeywell apply in the factory. Same item as supplied to HKS, so it really is HKS spec too Good choice BTW Adam. What are you going to use for an exhaust manifold? Regarding studs, they come as a 10 x 1.5 / 10 x 1.25 combination. Don't fall into the trap of using double ended 1.5 thread pitch. Not a good enough pull down on the gasket, and probable poor seal in the longer term.

I think your biggest limitation with the power chase is going to be the 10:1 DE base you are working from. It would be interesting to see how close to the detonation threshold you actually are, and what sort of ignition mapping you are currently running to avoid knock. I’ve seen a few 25DE+T producing ~300rwhp with pretty good efficiency and response, but nobody has made claims far beyond that. Turbine sizing is a balancing act in terms of mass-flow and rotor acceleration (read: boost response), so that while a smaller housing in the same family (eg Mitsubishi 8cm v 10cm, or Garrett 0.63 v 0.82 A/R) might give faster boost response, it will ultimately choke earlier. The critical aspect of that with running a 25DE+T is that you do not get the same pressure drop across the engine (ie. rising backpressure), leading to decreased scavenging efficiency, diluted inlet charge, rising combustion temps, and lower detonation threshold. You should inspect a 25DE piston, and note that they do have some sharp detonation unfriendly edges around the valve cutouts. Limitations wouldn’t be so much from the total mass flow through the engine, but the increasing combustion pressures and back pressure. Water injection would have to become increasingly important at some stage just to keep the engine alive. There is good reason to be cautious about what you could reasonably expect from further development, and the impact on engine life, so be careful. Even with a 9:1 25DET, you’d be making a different turbo choice for 260rwkW vs 300rwkW (longer term), and you’d expect a bit different driving experience from each. If response and capped hp was your plan, then a 0.78 split pulse EW GT3071would be reasonably innovative for the regular Skyline operator, but at a fairly heavy cost. Suggest that if you are currently running a Hypergear setup that you get in touch with them and try another of their higher flowing units with a bigger turbine capacity. Cost wouldn’t be too exorbitant, and at least you’ve got a bolt off/on proposition. The Garrett GT3071/76 units are very good. Good luck and let us know what you do.

Yes they can.

Sold...

You have the ability to alter what level of fuel enrichment is applied during cranking, and then post-cranking when the engine has fired. It is interesting to see how changing some values by a small amount can make a big difference, particularly in those areas where you get generally colder ambients of a morning. Increasing ignition dwell time down in the cranking zone is another way of getting a stronger start. I have a couple of files that may help - check email Regarding the fuel burn, it would be useful to log the AFR on accel, and deduce if it's in the accel settings, or fuel map.

Have a trawl around here: http://www.waterinjection.info/ There is some reasonably simple maths involved once you know what your actual water flow rate is, and compare that to your total fuel delivery curve. Somewhere around the 15% by mass of water:fuel should give pretty good results.

As listed, all functioning properly. Runs RB25DET $1200 firm. Located Sunshine Coast. PM if interested

I'd suggest that if the ported housing were available, or machining could be done, that it should be incorporated. There are a few examples in diesel applications where it is done to assist overall matching - I think Holset call it "band width enhancement" or something similar. To be honest, a free floating (externally gated) 0.73 A/R housing on a properly designed RB manifold would be close to the ideal from a total flow vs bottom end response balance point of view. Not quite going to be in split pulse territory, but it'd strike a damn fine balance. Otherwise, the 50 odd hp reduction in peak compressor flow capacity probably wouldn't be sorely missed if a 52T spec 700177-5006 cartridge and matching comp housing could be bought. Slightly less air "grab" might reduce the turbine drive requirements, and give quicker spool-up, while I'd expect the peak shaft speeds to be of no real difference to the 56T version. If that assumption is correct, there is an immediate advantage over the smaller 71mm comp which has to spin appreciably faster. I'm impressed that the twin scroll 3071 cranked out that much hp, but without even referring to the flow maps I'd have thought 26psi @ 4000 rpm would have things headed straight into surge, and critical overspeeding of the turbocharger. It's a shame to see a failure, but not surprising in the circumstances.

I like the general thinking behind this one. Is there a flow map available for that configuration? Interesting to see that HKS did not incorporate ported shroud into the comp housing. Do you know if that cartridge is actually available for purchase?

If using a 25DE head, then be prepared to have some machining work in order to fit cams with that sort of lift and not strike problems with coil bind in the valve springs.

Get on the phone to a reputable cam builder with your specifics. They will have something to suit your setup. Try Tighe Cams, or Kelford. Naturally aspirated cam specs are likely to be way different from forced aspiration specific. Unless going for regrinds you may well find that VCT is off the menu too. Should potentially be a good thing, plenty of snorting goodness. Please keep us updated with results, not just the cam specs you use.

If they stock an AVO type housing, be sure to take a couple of side-by-side pics with the OP6 just to show what differences exist (if any).

If you're looking to ream out the turbine, it's effectively increasing the cross sectional area - ie. a bigger A/R. Isn't the AVO style housing advertised at ~ 0.7A/R, while the OP6 is supposedly ~ 0.6? Worth considering if having a bolt-on is a must.

Once you've determined the cause of the run big end, and employed a remedy for the rebuilt/replaced bottom end so that it does not happen again, the actual build is fairly straightforward. The real work is probably in ensuring your clearances / tolerances are right before you screw the thing together.

I’m not suggesting the GCG option isn’t a good one, rather that Disco has a viable option available to him. Yep, GCG’s version provides bolt-up capability – and that would have to be the reason to pony up with the extra dollars they want for their product. Whether they work better or have better durability than other remanufacturing efforts is probably a matter of conjecture and OT. I agree that the bigger GT30 turbine combination is likely to give a different performance characteristic, but there is a degree of relativity from my experience. Vehicle usage – as always – should be the determining factor for what spec to run with IMO. Smaller impeller + tighter/smaller turbine scroll on a high flow should/will boost faster and plump out the torque curve down below 3000rpm, which is valuable for the street. Not into drags so I can’t comment about launching capability. I’ve not had any difficulties with the 0.87 Pro S spec for driveability or torque rise. It was completely linear, no surprises and definitely not a case of “nothing, nothing, smoke/sideways”. No doubling of hp in 1000rpm. Very predictable. And it allows the use of a fair whack of timing everywhere which is good for general response + overall power production. Your experiences with cracking manifolds is interesting. What weight difference is there between (say) a GT3071 combo, and a GCG high flow? Where did the cracking occur, and was it in a consistent location? The OEM manifold definitely has hot spots at the runner junctions. I do think it’d be a long stretch to suggest that a particular turbo induced cracks when there is a general lack of complaints from other owners using similar setups. Cracking would appear to be indicative of some fairly extreme temp cycling – what use did you give them, and do you know what sort of use/abuse those castings had been through before hand? I’m fairly sure Adrian has a lot of information at hand and will eventually choose what best suits him. The point I was making is that Wolverine’s comment about the GT30 being a viable, efficient alternative to a high-flow bears consideration. Good discussion. cheers

Adrian, having run with the 0.87 HKS Pro S option there is little to criticise about that turbo specification. Face it, the high flow option while reasonable is not likely to be in the hunt for overall efficiency or a "best match" between housing and impeller. The OP6 will allow a greater mass flow than a stock RB25 housing, but neither are in the hunt compared to a combination cooked up by Garrett engineers. There is little to criticise about the GT30 0.82 A/R combination, and it is a great alternative to the HKS Pro S housing. Unless you used a GCG high flow that allowed you to re-use the water + oil lines, there is an amount of plumbing work that would nullify any financial argument against using a proper GT30 combination. Plenty said about skylinecouple's results with his GT3071 / 0.82 combination over time, and he's hit pretty much the output/response target you seem to want. It may not be the absolute duck's guts for efficiency (read single scroll and wastegate not as nice as a HKS), but it's available, effective, proven, cost efficient, and neatly installed.

Question directed at both Gary and Paul: running a 25 head with custom grind non-VVT cams and hydraulic lifters Is the process in dialing the cams in any different, or any more (or less) worthwhile than with solid lifters? A mate suggested that the hydraulic setup introduces a level of imprecision not experienced once a solid setup is used. His suggestion is to follow the route advocated by Gary, while I'd steered towards making the adjustments while the engine is still on a stand and access easy. As always it's a different path towards the same/similar end, but interested whether hydraulics tend to confound attempts to get them dialed in by conventional means.

With some help from my mate, we knocked up this item. As shown, 90% complete - it needed a slit cut for the cable to slip through, and a coat of paint. One area we paid attention to was getting a dead straight pull on the throttle linkage. Hopefully our placement of the hole gives a nice sweep for the cable leading up to the bracket. Bugger all materials used in making the thing, but I don't think it would be easy to get the positions right with manifold and throttle body all bolted up to the engine. Very similar in execution to yours Warlord, and definitely handy to have some fabricating skills.

Yep, the end result sort of tells the story - I did notice that slight kink. Searching through my ally and steel supplies I may use either some 50 x 50 x 6 angle ally, or 50 x 6 flat steel as a starting point. Either way should work fairly well, but probably yours as a template is the easiest. Main point is to get that cable pulling from the right spot, in a fairly straight plane and avoid that bloody kink that I've seen a few people end up with as the cable runs into the plenum. thanks

Thanks for those - the detail is great. I'm in the same boat as zebra. Do the angles work ok?

In some ways it's like upsizing the turbine. Less restriction to the whole air in / air out process should equal easier power. Can you post up a decent picture of the throttle cable mount?