Gt3071

[discopotato03]

No Lithium neither , there have not been many of either of them out here until a year or so ago . Most had either the T04S compressors or the cropped turbine/wrong housing in the 3071R 's case . So no I can't tell you how the exact real word experience feels . I think Cubes and a few others understand what I call the windmill effect that good matching gives and thats what I want as well as good on boost torque . I have been there with engines where you had to chase the "boost curve" so that the thing would go if you prompted it , it ment driving round at higher revs and lower gears which wears a bit thin in time . My last engine/turbo did all that (windmill etc) and would pull strongly to about 6800 revs - plenty for me .

Later .

[Dale FZ1]

I think Cubes and a few others understand what I call the windmill effect that good matching gives and thats what I want as well as good on boost torque .

The effect is understandable, but as per your first post, I think we are on the same page viz. appropriate speed ranges for the 71mm compressor. I think that the GT30 may just flow a little too freely compared to a GT28 based unit, so inhibiting the ability to accelerate the 71mm compressor up to speed where it is pushing appreciable air mass (ie. generating boost). Sure, the free flow promotes much less top end bottling of exhaust, and lets the compressor run to its maximum capacity more easily; but I'd suggest that there may be more overall advantage in teaming the GT30 turbine with a 76mm compressor in some specification. I'd predict the result as having negligible difference in perceptible response or lag, but with the capacity to generate more torque at higher engine speed while equalling the 71mm down low. If costs involved in the install are the same, it makes for an easy choice.

For the speed range and capacity of the 71mm compressor, I'd be inclined to match it with the smaller GT28 spec turbine even if it means using a stock/modified Nissan housing. I agree that the GT3071 is something of a wildcat and therefore difficult to pigeonhole within the performance spectrum. That comment applies equally whether the 71mm compressor is teamed with the 60mm turbine, or its cropped 56.5mm brother.

So it becomes more an issue of identifying where abouts in the power:response equation your performance needs are and then choose accordingly.

Hopefully this discussion will prompt some comment from someone who has driven/tuned engines with the types of turbo being discussed.

Hope that clears the air, and kept topic on track.

Edited March 30, 2007 by Dale FZ1

[Lithium]

No Lithium neither , there have not been many of either of them out here until a year or so ago . Most had either the T04S compressors or the cropped turbine/wrong housing in the 3071R 's case . So no I can't tell you how the exact real word experience feels . I think Cubes and a few others understand what I call the windmill effect that good matching gives and thats what I want as well as good on boost torque.

Argh if you ever are in NZ, let me know and I'll take you for a drive in mine I understand your theories, but thats all they are. What really matters is how the car ACTUALLY performs. You're saying what will provide said driving experience, I'm saying mine does it. I could probably match if not out accelerate a stock R33 GTS25t in 5th from 100kph, and the car makes solid power up to 7000rpm - what more should I be aspiring to?

I'd love to drive a car with a GT3071R or 52T GT3076R to see the difference, but as it is my combination is one of the only GT-BB GTSt Skylines I've come across.

Cubes - I like your concept Very cool.

Edited March 30, 2007 by Lithium

[BOZ22N]

as disco was talking about earlier i have one of the proper GT3076R t3 ext gate i checked the serial number on the cartridge with his specs and it added up. i have yet to get her tuned properly but with hks cams she sure does sound the money, but i will let you know how it turns out. but with my crappy driveway tune it reached .86 bar at 3900 rpm so it is looking good thus far.

Edited March 30, 2007 by BOZ22N

[Cubes]

as disco was talking about earlier i have one of the proper GT3076R t3 ext gate i checked the serial number on the cartridge with his specs and it added up. i have yet to get her tuned properly but with hks cams she sure does sound the money, but i will let you know how it turns out. but with my crappy driveway tune it reached .86 bar at 3900 rpm so it is looking good thus far.

Looks like a nice base for cracking 300rwkw.

Built bottom end or just a headgasket to drop the comp a touch so you can push 20odd psi in to it?

[discopotato03]

Hi Dale , a contact in the US (a very capable fabricater and tuner) has managed to get phenominal mid range torque like 400 ft/lbs at 4500 rpm from a developed SR20DET with the divided .78 A/R housing (see ATP Turbo.com for housing pic) and a real GT3071R . Everything about the turbocharger is std except the divided turbine housing which is T3 flanged and looks identical to the housing on the non gated Garrett GT32 series plain bearing turbos ie GT3267 and GT3271 (can see them at turbobygarrett.com/products/turbos etc) . He is saying that they are getting results previously thought impossible with that engine/engine speed . He thinks this is what I should run for a punchy responsive RB25 with about 300 wheel Hp . On the face of it 300 WHp may not sound like a lot but its the broad torque band I'm interested in , can anyone tell me what sort of WHp and torque numbers in ft/lbs good quality 235 width road radials can hold ?

Cheers Adrian .

[Dale FZ1]

Hi Adrian

Well here's a punchy, responsive 300rwhp from my GT2871R 48T highflow @ 13psi:

That unit on an internally stock engine is particularly responsive, and progressive in its delivery. Max power is developed @ 6400rpm, so the useable rpm range is same as factory and the gearing is suitable for the delivery in a road application.

It's worth pointing out that my (and your targeted) power level (~225kW) is some way below the 260 odd kW that was the target in the original thread query about the GT3071. As per many discussions about upgrades, the individual has to set a clear target on power, and understand how certain specs can/will/do impact on delivery.

My view is that with the GT30 based turbines applied to a RB25 the useable engine rpm range general shifts upwards by 500 or 1000, or maybe more. So it becomes an exercise in choosing the optimum compressor spec that can cope with that shift and still give good results. While the GT3071 may deliver 240 or 250rwkW, I remain out on the limb and say that the quicker responding GT28 based turbine will eat it for bottom end response, and with the 56T GT2871R core still deliver the same/similar top end numbers. For me it makes it hard to put together a compelling argument for the GT3071 into a road application in that instance.

Move into the GT30 range with the option of 71 or 76mm comp, and again I feel that though their response capabilities may vary, it will be by a small margin of little practical consequence. That difference may be tailored by the use of either the 7 blade TO4S compressor or the 6 blader and the different pumping characteristics they have. But it is worth considering that either spec offers bigger flow than the 71mm and won't drop off at higher engine speeds. When you consider that the useable maximum engine speeds are going to be up by 500-1000rpm, that is an important aspect in making the choice.

For me then, it's like drawing a line in the sand and deciding which side to stay on: stock engine speed range and moderate power, or elevated engine speed range and higher power. With the higher power option, it is still possible to have a satisfactory bottom end delivery but not likely to equal the lower powered, smaller spec GT28 unit(s) that I've alluded to. They payoff comes in that lesser restricted high end flow.

It's interesting that your US contact has reported those results, but we are ignorant of just what internal engine changes have been made to yield numbers like that. It's also on a different capacity 4cylinder.

The use of the descriptor "wildcat" with the GT3071 is probably very apt - it's often used in shooting with special modified rounds intended to fill some small niche. As you've indicated, it seems to need things "just so" to suit it. When applied to a RB25 I'd think it means either accepting its shortfalls with a stock engine, or effort and expense to make it work. The logical options within financial boundaries seem to be either run with the smaller 2871 units, or the bigger 3076 units and reap either better response or more power.

FWIW, I do believe we're generally on the same page but it's important to stay on-task with the original query about an RB25 application. 300hp is a lot different from 350+. I also happen to believe that your target of 300hp is about as high a useable (stress that word) amount as can be applied to a road car if you want it to get to the ground. Check below - that looks impressive, feels great, but it was one of the slowest cars at that event on that day.

Edited March 31, 2007 by Dale FZ1

[wolverine]

HKS GT_RS powered stagea has no issues with traction. ok, it can shift torque to front wheels but it puts the power down pretty comfortably to the rear wheels. it makes more power down low and mid-range than a GCG hi-flow(back to back tested in our case), top end is hard to pick since in theory they both have similar sized compressor wheels. having read threads where some claim to have taken them up to 300rwkw (but lets say 260-270 with a cam upgrade) then there is a bit of headroom if you want to push them.

there is a cost premium but the cost premium is narrowed if you sell your standard turbo, so it is worth considering.

consistent with what dale is saying they seem to work well on RB25DET's.

[dangerman4]

this was my old gt3071r-sp

running a vg30 exhaust housing on a stock r33 gtst

just usual mods and its an auto.

i have since sold this to "Robbo" so he might be able to add some more info in regards to power from his manual 33

[Dale FZ1]

Thanks Darren

the max power number is very commendable. Shame that it is scaled in road speed, not engine speed.

Can you add to the discussion with regards to delivery, and how it compares to your new setup? (from memory you went to the 3076?)

[discopotato03]

Dale that 300 WHp was just a suggested number and I think I can do that and a bit more with better (for me) torque characteristics . Mine is not about a std engine , I don't particularly like the std characteristics of them and porting + mild cams should alter these to better suit me .

Wildcat , yep exactly why I used that term - redneck cartridge .

I don't necessarily agree that the GT30 turbine based turbos have to have the response penalty but more money and effort is needed to have ALL the benefits .

Cheers A .

[dangerman4]

Thanks Darren

the max power number is very commendable. Shame that it is scaled in road speed, not engine speed.

Can you add to the discussion with regards to delivery, and how it compares to your new setup? (from memory you went to the 3076?)

power delivery was very good thru the midrange.

as you can see. the rev limiter was at 7k so halve that will give you revs at road speed

i now have a forged bottom end so i went to the new gt3582r-iw with a .82 exhaust housing.

but you have to remember its a auto, so that helps it spool up better.

on a manual 2.5 ltr its certainly not what i would run, but the auto loves it.

first tune with gt3582

317 kws at just over 24psi

second dyno

with poncams and fully built trans and hi stall

299.9kws at 21 psi.

but im not sure if this info will help you topic or side track it further.

cheers

Darren

[Haines]

Darren

why did you use the VG30 Rear housing and what A/R are they

Ive got an R34 Auto and this is the turbo i was going to get

but was going to get it with the .82 Internal gate

but i was thinking i could save money if i sent my housing down and got it machined out rather then buying the new one

Did the VG30 housing run out of top end and how was the response??

[dangerman4]

Darren

why did you use the VG30 Rear housing and what A/R are they

Ive got an R34 Auto and this is the turbo i was going to get

but was going to get it with the .82 Internal gate

but i was thinking i could save money if i sent my housing down and got it machined out rather then buying the new one

Did the VG30 housing run out of top end and how was the response??

im not sure myself but i was told there in the low .7 A/R area.

i think the r34 and the vg30 exhaust housing are very similar if not the same thing.

well seeing as the dyno is still pulling at redline i wouldnt say it ran out of top end, but if you want bigger and better then the new gt3082r-iw / gt3040r-iw internal gate is for you.

reponse was fine...

[Dale FZ1]

power delivery was very good thru the midrange.

as you can see. the rev limiter was at 7k so halve that will give you revs at road speed

i now have a forged bottom end so i went to the new gt3582r-iw with a .82 exhaust housing.

but you have to remember its a auto, so that helps it spool up better.

on a manual 2.5 ltr its certainly not what i would run, but the auto loves it.

but im not sure if this info will help you topic or side track it further.

Well it does side-track somewhat, but does add to the understanding. With the results you now have, it must feel something akin to the Coyote sitting on an Acme rocket It would doubtless be very entertaining whether inside the car, or watching.

My main issue was/is the type of transient response/spool that the 3071 offers, and whether it sits in no-man's-land when compared to the smaller 2871 or 3076. Mid range would not be where I perceive it has a weakness.

Mated to an auto, with kick-down and the stall-up of the converter, the 3071 would/should be a pretty good thing because that bottom end is masked.

Adrian, I'm in agreement that the stock engine has limitations and as always it is $$$ and effort that makes the difference whether a specific setup goes together and works in harmony. The light bulb went on for me when you said 300, because that was my target as set and achieved. I'd have to conclude by saying that virtually all turbo specs have their limitations or compromises. The smart operator will get satisfaction by either identifying or accepting them as part of the package.

Variety in options is what makes upgrading mechanical specs a lot of fun or a hair tearing exercise and promotes discussions like this one.

cheers

[Robo's]

this was my old gt3071r-sp

running a vg30 exhaust housing on a stock r33 gtst

just usual mods and its an auto.

i have since sold this to "Robbo" so he might be able to add some more info in regards to power from his manual 33

Sorry for the lack of response regards to dangermans GT3071R but i havent been able to drive it much due to the lack of a license. Had some friends tune it on the road with me in the passenger seat and we are certainly seeing some big gains over the 2535. Dialing in over 20psi gives it some big mumbo, squeeling the RA1's coming onto boost in 2nd gear. At 16psi power feels linear, definately doesnt give you the excitement of 20psi+. What i havent ironed out is the boost drop with a suitable controller. Im getting a jaycar IEBC soon after my PFC somehow doesnt want to control boost and the manual turbotech's arent upto scratch with too much boost creep. So i have been relying on using the adjustable actuator.

[turboedsloth]

does anyone know how the GT3071R with .63 A/R housing would go on a unopened rb20 with fmic, gtr inj an supporting mods like that