Rb25det With A "real" .82 A/r Gt3076r

[Lithium]

Hi all

I have been lurking around the SAU forums and gaining information from here and other places from before I owned my R33 GTS25t up until now, and will no doubt continue to. I had (and many others will still) have researched and pondered furiously the not so age old "What turbo should I go for question" and I have ended up with a combination that is so far PERFECT for my needs. Its been brought to my attention that people have been following my progress, and others - and that it might be handy to post my findings.... so here goes

After all my research I ended up shortlisting and considering long and hard the HKS GT-RS, the 56Trim Garrett GT3076R, the Garrett GT3071R (which I consider to have been NARROWLY my second choice), and a Holset HX35 (got ruled out when I figured I probably wouldn't fit it low mount). After all my deliberation, I ended up with an initial "winning combination" which consisted of:

- Garrett GT3076R with .63a/r Ford Style turbine housing (yay ATPTurbo)

- Factory Exhaust manifold with 10mm spacer (needed to clear rocker cover), wastegate mounted off the turbine housing of the turbo (BAD move - don't do it, boost creep galore)

- Completely stock RB25DET

- Nismo 555cc Injectors (yay Greenline for particularly good service on getting these to me)

- Walbro 255lb/hr in-tank pump

- TiAL 38mm External wastegate

- GTSLink Plugin ECU

- Cheap front mount intercooler kit

- 3.25" MomoCorsa Exhaust with no cat

This setup had a MAJOR boost creep problem, even after porting out the internal gate port the Ford Style wastegate setup provided - it rather sucked. I also ended up with huge ignition breakdown issues which was a big pain in the arse. Nonetheless - here are some pics of this stage being put together and running:

Turbo:

Turbo test fitted (note spacer):

Internal gate housing with ported out wastegate feed:

Wastegate fitted to turbo:

Engine bay with it all in:

end of stage one.... will start writing stage two going straight away..

[Lithium]

OK - so, first things first - ignition problem kicked in from about 4500rpm.... was a nasty nasty misfire. This was fixed using a Mitsubishi V6 ignition module (Spec2 R33s don't have one ) and a set of wasted spark friendly Buick V6 (Commodore mate) coilpacks. This so far has proven to work a treat!

The next and more pressing issue was the boost creep - the first direction of attack was to cut the feed back into the exhaust stream off the wastegate and just have it venting externally. This made a huge racket, and SLIGHTLY reduced the creep - but really all it did was made a bunch more noise. Not cool - I only mention this as it was a path I went down, others might as well.

Naturally, I had to road test it to see how it behaved - and now that I've had both the .63a/r and a .82a/r turbine housing I feel qualified to comment on the comparison. I'd love to tell you boost threshold difference on the dyno, or loaded up from low revs in a higher gear - but unfortunately there seems to be none. I don't know if this is because I went to a tubular low mount manifold when I changed to the .82a/r or not, but nonethess with either of them I can get boost from 2000rpm in 4th gear, and on the dyno they both made 9psi by 3300rpm.

On the road however, there is definitely a difference - I definitely have a bit more lag. Interestingly enough, I prefer it - it makes a MUCH more streetable car and I wish I went with the .82 in the first place. Basically think of the lag as "how rapidly the turbo winds up once you've got positive pressure". They both feel exactly the same off boost, and seem to get to positive pressure just as easily...

With the .63 so long as you are over "reasonable boost" (in my case I consider as 9psi/3300rpm) threshold then if you lean on the throttle the feeling is much like someone has cut a rope tying you back when you are attached to an elastic band at full stretch. You don't instantly get fired off, but you get quite a violent brisk bunch of acceleration. Now if you do exactly the same thing with the .82a/r, imagine a brisk take off in a jet aircraft.... thats the best way I can describe the sensation of them coming on.

My experience test launching both setups says a bit -- I tried launching at 3500rpm with the .63, it had enough to get the tires spinning initially - and would snap on to wheelspin as the boost rose. I would gradually back off until the tires were more or less able to hold and try and hold that balance. When the revs went further up, the turbo would get a wiff of more exhaust gas and leap into life again - all keen to start toasting tires again. Basically it felt really really jumpy with this setup.

With the .82a/r, launch would be much the same - except imagine the way the turbo reacts to the throttle control as more like how a jet (there goes that metaphor again) engine would react to throttle control. Back off to a point where its nice, and it will give you that thrust. Put your foot down more, and up goes the tires in smoke. With both setups, a gear shift near redline has you sufficient revs that when you put your foot down again the car bursts into life - no worry about falling of boost at all.

Soo.... I didn't like the "better spool" of the .63a/r turbine housing as much as I thought I would, and I have a boost creep problem with the setup I have. I can either completely change it all to a high mount and a proper feed to the wastegate, orrr.....

[Lithium]

While all this was going on, I had been talking to fellow SAU'er Cubes who was looking for a decent turbo setup for his RB30DET powered R32. I had sung my praises about how good off throttle the GT3076R was, and how well it spooled and how willing I could tell it would be to make lots more power. There is also how cool the anti-surge whistle is.... hehe

Anyway, after some deliberation HE went for a .82a/r internally gated version of the GT3076R which made ME watch with great interest. He finally got his car going, and I'm sure a few people here know the results. In short, it made good power, drove awesomely, and most importantly for me - it held boost. After muttering and swearing about my efforts and theories as to how I was going to fix my problems, I PMd Mr. Cubes and told him about what I was pondering. He was extremely helpful, and even went to the effort of hooking up a deal with ATS to get me a turbine housing and actuator from them - as in NZ we don't have people who stock such things separately. THANKS CUBES!!!

I got my nice new package in the mail, and amped for the next few days about getting it on haha. Somewhere along the line I also impulse bought a low mount stainless steel exhaust manifold because they are cheap and I was on a bit of a drop-exhaust-manifold-pressure mission. Interestingly enough, with the new exhaust manifold and the new turbine housing - I didn't need any spacer. I don't know how much to do with the design of the turbine housing that was, and how much to do with the new manifold - but either way, it sat a little lower and was a much nicer fit. Also gave the exhaust a pretty sweet tone haha.

As soon as I drove it, I was stoked. In normal driving its barely noticeable, on the motorway in 5th gear from 100kph it has SLIGHTLY less urge, almost like what you'd expect driving at a higher altitude. Who really wants brisk acceleration from 2600rpm anyway? Its nice not having the thing hissing like a hissy thing the moment you get under a slight bit of load. The BEST thing was when I gave it a bootful and the needle stopped climbing after it hit full boost. COOOOOOL!!

So, I drive it around a bit getting used to it - and in to the dyno. Dyno tune was a mix of good and bad news. Basically, the wastegate would open at around 10psi - I wanted to run ~15psi and I had no form of boost control other than the adjustable preload on the wastegate. We wound up the preload until it seemed like it was going to be silly going any further. As it is now, the wastegate opens at 3600rpm at around 13psi and creeps to 15psi by 7000rpm... peak power attained at 6400rpm running 14.2psi so its not TOO bad but could be better. My next purchase is going to have to be an electronic boost controller to fatten up the midrange and maybe get a little more peak power.

Nonetheless, was happy being able to get a full tune into the car - make some semi reasonable power and just have a really really driveable car. The tuner asked what kind of fuel was in it, he's tuned R33 GTS25ts with upgraded turbos along the T3/T4, GT2535 and GT2540 lines and has found them to start getting a little iffy above 240kw @ wheels in terms of timing and detonation. I got NO detonation on the dyno. He'd add timing, it'd make more power. Add a bit more timing, a bit more power. Add a bit more again, and the gain is minimal... ok so thats what it needs. No pinking, no dramas.

So - some pics relevant to this stage of modification:

New housing Cubes sent over:

Dodgey cheap low mount manifold I bought:

Wasted spark setup on the firewall:

Internally gated turbo on low mount manifold:

Dyno plot:

Hope this reads as more than a boring wank on about my car actually starting to go properly, and has some informative use. Any questions more than welcome - I post this to hopefully help other peoples mission looking for a nice turbo setup for a stock RB25 that they MAY want to take to the next level at some point... I think this turbo is the best choice for being able to cater for both.

[Cubes]

Basically, the wastegate would open at around 10psi - I wanted to run ~15psi and I had no form of boost control other than the adjustable preload on the wastegate. We wound up the preload until it seemed like it was going to be silly going any further. As it is now, the wastegate opens at 3600rpm at around 13psi and creeps to 15psi by 7000rpm... peak power attained at 6400rpm running 14.2psi so its not TOO bad but could be better. My next purchase is going to have to be an electronic boost controller to fatten up the midrange and maybe get a little more peak power.

lol.. identical to how my 1bar garrett actuator builds boost without any form of boost control.

Mine on the dyno made 11psi at 3k then 1bar by 4500rpm. With a cheap ball/spring bleeder on it it shifted 19-20psi to a little over 3000rpm.

I have been told its typical of garretts 1bar actuators. Helps with traction through the mid range with mysetup though.

I'm very glad your not disappointed with the additional lag from the .82 it was a worry I had being on the 2.5ltr.

[dangerman4]

well done on all the info.

question time...

what does your dump pipe look like now?

as i have a dump pipe to suit your exact turbo for sale on ebay at the moment.

the actuator you are running is that a 1 bar actuator from garrett?

have you considered going higher? maybe 18psi?

i ran a very similar setup 18 months ago and had similar results.

same manifold similar turbo etc.

[series2r33]

I order a GT3040r (600 flywheel hp rated) internally gated turbo with the .63 a/r,

The GT3076r is the 500 flywheel hp rated turbo yes?

Do u think theses turbos would have around the same power output and curve on the same boost since the GT3040 has the .63 and the GT3076 has the .82?

Edited October 16, 2007 by series2r33

[Cubes]

Darren;

yeah. He's running the same 1bar Garrett can that I am.

Matt;

The GT3040 with the .6 rear is a waste as you require better than pump fuel to make the most of it. Essentially you sacrifice response and spool for nothing.

A good example of this was R33racers old setup; GT3040 made around 320rwkw on pump; water injection (similiar to running nice fuel) had it up around 370rwkw. Dropped the GT35r on and it made the same power as the GT3040 but on pump fuel; no water injection required.

The Gt3076r is 525hp rated and can push 320rwkw with a set of cams and exh manifold on low 20psi behind a manual. I've been told they max out around 350rwkw with water injection/good fuel.

Regardless how big the compressor wheel is or how much it is capable of, if you can't flow the required exhaust gas past the turbine wheel its simply not going to make the power of which the compressor wheel is capable of. This is especially true on pump fuel as you quickly run in to detonation problems when the scroll backpressure skyrockets. This is why good fuel or water injection is useful. Remember a motor is nothing more than an air pump.

I wouldn't consider the GT3040; it was a turbo of choice when the GT3076r (aka HKS3037S) wasn't available and the crappy GT3076 with its 7blade comp wheel and .7 comp cover was. Jump straight to the GT35r or stick with the GT3076 & 71.

[Lithium]

what does your dump pipe look like now?

as i have a dump pipe to suit your exact turbo for sale on ebay at the moment.

Not quite sure what you are looking for with that question. I basically bought a laser cut flange for a XR6-Turbo and effectively a pair of separate dump pipes were made up - one for the turbine outlet and a 2" one for the wastegate outlet. When the main exhaust bends to the back of the car the wastegate dump pipe merges into the main exhaust flow. You can clearly hear when the wastegate opens, even though it flows with the rest of the exhaust stream. I'll see if I can get a photo of it

Why did you change your setup?

Edited October 16, 2007 by Lithium

[Lithium]

I order a GT3040r (600 flywheel hp rated) internally gated turbo with the .63 a/r,

The GT3076r is the 500 flywheel hp rated turbo yes?

Do u think theses turbos would have around the same power output and curve on the same boost since the GT3040 has the .63 and the GT3076 has the .82?

I actually think a GT3076R .82a/r has MORE power potential on a fairly stock RB25 than a GT3040 .63 on the same boost level. Reason is, it breathes out the rear better and at higher boost levels will result in far lower exhaust pressures which ultimately means less restriction and you can as a result often get away with a bit more timing and therefore more power. The 82mm compressor of the GT3040 (aka GT3082R) only really has an advantage in higher flow capacity for a given boost level. If the engine isn't being choked by the compressor - which you aren't likely to get with the GT3076R ESPECIALLY if you are running stock cams, you aren't going to be in a position where the GT3040 has any advantage.

The .63a/r GT3040 I'd imagine would be a tad lazier than a .82a/r GT3076R given the extra inertia from the 82mm wheel. I won't swear by that however haha. At best it would comparable- though thats just theory, someone on here who has exposure or more knowledge may be able to shed some light.

[The Mafia]

lol at all you dudes that copied off my turbo setup - haha lithium you even went the spacer like I did.

I don't care, I'm just saying. Its funny how I have set a trend

Thank dale_fz1 for the extensive research on the turbo to. I just bit the bullet and tried it.

AS for the boost creep - I have a 0.63 rear housing with the smaller wastegate flapper and I can run 18psi and hold it to 7,000rpm. I think I am doing pretty bloody well. I have a 0.82 garrett rear that I might have to send off to ATP and have it modified and I'll use it for my 3.0l block.

Nice work none the less.

These 56trim GT3076's seem to be the tits.

Here is my 300rwkw thread for reference: http://www.skylinesaustralia.com/forums/in...p;#entry3100546

[Cubes]

I was originally really interested in the HKS3037ProS as an old Adelaidian SAU'r Steve had an HKS3037S on his RB25DET with first the .69 then the .87 HKS turbine housing back a good 4years odd.

With a little over 20psi a set of cams and exh manifold it made from memory spot on 323rwkw.

Then I discovered the 6blade Garrett .6 port shroud is the same thing just had to wait for the int gate housings to be sold.

Why do you have to modify the .8 rear Mafia? I run the small std wastegate hole on mine and it sways between just under 16psi and 15psi due to the crappy actuator and long boost reference point from the plenum.

I should disconnect the actuator and see what boost it peaks too.

[Zilch*]

Hi Lithium, nice writeup mate and congrats on the setup. Incase your interested my R33 is running a GT3071R and made 270.1 rwkw at 14psi. I can post up the dyno sheet if you like.

Cheers Steve.

[Devils_Advocate21]

Nice write up. Got a spare hks internal 0.87 housing that would fit that turbo if ya interested the mafia. Btw how those under bonnet temps going with that stainless mani you got there?

[discopotato03]

Go Lithium .

Yep the Garrett GT turbine housings are always going to be a better match for their GT series turbines , the volute and nozzle section are designed to work with those UHP family turbines where the American spec Ford style T3 ones are not .

This shows up as you found with higher turbine inlet pressure and larger flat valves don't often do much good .

Just on those IW type actuators or "cans" . They are not really designed to be adjustable other than to get some pre load on the valve to initially hold it shut . If the shaft is made length adjustable and you keep making it shorter what happens is that you are eating into your diaphragms limited travel , meaning while the spring load may climb a bit the diaphragm bottoms out earlier and the valve now can't open as far as it may need to .

I noticed that you had an external gate on the T3 housing and some places in the US do this for some reason .

Probably the chief disadvantage of IW is that the exhaust gas has to make a sharp 90 deg turn out through the side of the turbine housing and another to go south out the dump pipe . Provided the exhaust gas velocity is not too high its quite a reasonable way of doing the job . When gas velocity gets really high it doesn't want to know about changing direction any more than it has to so the IW can lose its ability to regulate mass flow through the turbine , pressure in the housing climbs and boost creeps upwards .

You get a bit more say in waste gate valve size with externals though as we know that introduces other issues , as Lithium found the larger valve or hole anyway doesn't always fix the problem .

I've seen so many people use non native turbine housings particularly IW ones and strike creep problems . Another nasty that can happen is the larger flat valve having more area for the hightened exhaust manifold pressure (turbine inlet pressure) to act on is forced open more easily so the punter uses higher and higher spring loads to hold the valve stut . Naturally turbine inlet pressure goes ballistic and the engine is in danger of killing its pistons or at best not making the desired power levels . This is why I've been harping here for years about the evils of high turbine inlet pressure , and getting the turbine/compressor match right , and that if you don't get the turbine/housing combination right it won't work as well as it should .

Here we go again they'll say , a PROPERLY designed twin scroll system gives more of the same mainly because it allows even lower turbine inlet pressure , it allows the use of larger turbine housing A/R without the turbine lag penalty , allows us to run the compressor to its limit without turbine inlet pressure restricting the hot side while it does .

Now depending on how fast you spin it the real GT3071R's 71mm 56T compressor maxes out at around 440 Hp's worth of air . If you could have the turbine response and have enough low restriction exhaust flow to get there the result should be pretty good I think on an RB25 .

For the 3L people , fingers crossed , there could be a twin scroll T3 flanged GT35 turbine housing in 1.06 A/R next year . If Garrett are smart they may cast enough material into the blank to be able to profile it to suit the GT30 turbine as well which could be very interesting on a GT3076R .

Anyhow good results and thanks for posting your journey , cheers A .

Edited October 16, 2007 by discopotato03

[The Mafia]

Hi Lithium, nice writeup mate and congrats on the setup. Incase your interested my R33 is running a GT3071R and made 270.1 rwkw at 14psi. I can post up the dyno sheet if you like.

Cheers Steve.

look, I don't want to start a war, but could you post your mods? 270rwkw out of a GT3071 at 14psi sounds very far fetched. If I take my WMI kit away, I can only make 270rwkw on the GT3076 at 18psi. Do you run it down the quarter? Do you have a Terminal speed I can see?

Its probably a good idea that we don't compare dyno figures due to this problem I see every day of dyno's being way to happy. It sounds like your dyno is happy by about +20rwkw. What is your torque?

Here we go again they'll say , a PROPERLY designed twin scroll system gives more of the same mainly because it allows even lower turbine inlet pressure , it allows the use of larger turbine housing A/R without the turbine lag penalty , allows us to run the compressor to its limit without turbine inlet pressure restricting the hot side while it does .

Now depending on how fast you spin it the real GT3071R's 71mm 56T compressor maxes out at around 440 Hp's worth of air . If you could have the turbine response and have enough low restriction exhaust flow to get there the result should be pretty good I think on an RB25 .

For the 3L people , fingers crossed , there could be a twin scroll T3 flanged GT35 turbine housing in 1.06 A/R next year . If Garrett are smart they may cast enough material into the blank to be able to profile it to suit the GT30 turbine as well which could be very interesting on a GT3076R .

Anyhow good results and thanks for posting your journey , cheers A .

ahaha, in comes the twin scroll idea again.

Disco, have you tested and proven this system yet? I'm still not convinced all the expense is really going to give you that much more power on the RB25\30 due to it already having a much larger engine capacity to get the turbine moving.

I understand there have been average results on the smaller 2.0l engines, but I'm not convinced that it will be something that will work as well on a much larger engine like the RB30.

We probably shouldn't start this into a Twin scroll thread though either.

Cubes: Well, I just thought it might be a good idea to have that extra room in the wastegate if I am going to run 20psi? I'd like to push about 320rwkw in the long run (with WMI of course) but I am sure that the turbo doesn't really have much legs left in it. I'll have cams for sure though. What do you think the limits will be with a setup like yours? Probably with the boost up in its most efficient area (about 22psi)

Lithium, well done though, Its good to see people making the same results as I have. All you need now is a set of cams an a water meth injection kit.

[Zilch*]

look, I don't want to start a war, but could you post your mods? 270rwkw out of a GT3071 at 14psi sounds very far fetched. If I take my WMI kit away, I can only make 270rwkw on the GT3076 at 18psi. Do you run it down the quarter? Do you have a Terminal speed I can see?

Its probably a good idea that we don't compare dyno figures due to this problem I see every day of dyno's being way to happy. It sounds like your dyno is happy by about +20rwkw. What is your torque?

ahaha, in comes the twin scroll idea again.

Haha don't worry mate I'm not the fighting type I was pretty suprised by the dyno results as well, it was done at MRC performance in castle hill NSW by the way and I will still post the dyno sheet up when I take a photo of it. I haven't taken it down the quarter yet but I'll post a result when I do, though with my lousy driving it won't be spectacular.

Anyway, here are the mods:

on stock internals

GT3071R (it was an XTR kit, maybe that means something to you?)

Nismo 555cc injectors

Tomei 600hp fuel pump

Nismo adjustable FPR

Splitfire coilpacks

Denso iridium spark plugs

HKS turbo back exhaust with JJR split dump pipe

Hybrid GT spec FMIC

Oil cooler and filter relocation kit

Cusco oil catch can

Greddy profec b spec II dual stage boost controller

Haltech e11v2 ECU

Davies Craig twin thermo fans(12" I think)

Davies Craig electric water pump

HKS exhaust cam gear(currently just set to 0)

Plus all the usual stuff like the custom piping, freshly machined manifold, braided lines etc.

Soon to be on there will be a plazmaman plenum, aftermarket exhaust manifold and a high flow cat

Not too sure how it works as I'm no mechanic but even the tuner was suprised at what he got out of it

Edited October 17, 2007 by Zilch*

[Cubes]

Disco,

lol at the twin scroll.

I've had a play with twinscoll turbines in the engine analyser simulator; it definitely looks promising.

The only issue is the internal wastegate.

I would be very curious to see how the 1.06 twin scroll drives as I wasn't impressed with the light load/part throttle boost response from the 1.06 GT35 on the RB30 in comparison to how the .82 drives.

The boost response and low gear acceleration from the .82 was so so much more enjoyable.

The 1.06 feels super lazy until a little before 4k. But its all a trade off; peak power or average. Hopefully the twinscroll can blurr the fine line.

Mafia,

I would hope mine tops out a little over 300rwkw with the .82 on pump.

I have a set of cams as you may know. 265duration 8.9mm lift. Cheap regrinds so nothing is really lost of they kill low end; i'll grab another and have them reground to the 254duration spec that I know is a good thing picking up around 25-30rwkw on the same boost with no loss to low end.

If I ever drop a nice exhaust manifold on mine I will most definitely sell the GT30 and drop a GT35 on it. Behind a manual and with some nice cams it shouldn't have too many problems pushing high 300's. Providing I keep rev's sensible the trusty old rb30 bottom end will hold the power fine.

Zilch,

Are you running the .6 or .8 turbine housing?

The .8 obviously allows the motor to breathe a little better as a result you don't require as much boost to make the same/similiar power.

[Zilch*]

Hi cubes, it's a .8 turbine housing, I'm a newb with cars but any questions you have about the car's setup I'll try and answer and I will post up the dyno sheet shortly.

[Lithium]

Zilch - Nice man I'll have to have a look at your thread. Yeah, at the boost and power level you are making the GT3076R has no major advantage over the GT3071R on a stock RB25 looking at the map. Its more the potential when I start getting more aggressive that the GT3076R has.

lol at all you dudes that copied off my turbo setup - haha lithium you even went the spacer like I did.

I don't care, I'm just saying. Its funny how I have set a trend

Thank dale_fz1 for the extensive research on the turbo to. I just bit the bullet and tried it.

WTF mate?? You had nothing at all to do with it. Neither you or Dale FZ1 deserve an ounce of my thanks. I had the 56T GT3076R for ages before you got yours, and had decided way before then. As far as I am concerned there is more of a chance that you copied or got inspiration from my or DP's ramblings. DiscoPotato deserves some credit for swaying me for .82 and Cubes a lot ... so thanks you guys for your opinions and help. And you are welcome for my input when you were thinking about what to change with your setup and were still fighting with the 52t:

http://www.skylinesaustralia.com/forums/t1...um#entry2857161

For an additional reference, here is a dyno plot of my car running the .63a/r housing with a .6bar spring and creeping to nearly 20psi:

Mr Mafia - you do realise you NEED a spacer to space a turbo too big to fit on the stock manifold away from the motor? Its not to copy you, its because you need to do it. I have no spacer now either....

Edited October 17, 2007 by Lithium

[Robo's]

Hi Lithium, nice writeup mate and congrats on the setup. Incase your interested my R33 is running a GT3071R and made 270.1 rwkw at 14psi. I can post up the dyno sheet if you like.

Cheers Steve.

Ive got the 3071R on mine and set to low boost (maybe around 15psi) it certainly doesnt feel anything near 270rwkw. In actual fact my old 2535 would tear it to shreads. But set on 20+psi and its a different story, certainly got some balls. I dont have any dyno figures as i do most tuning on the road with my wideband sensor