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


Lithium
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Zilch - Nice man :P 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.

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....

whoa man, you need to settle down a bit.

I was only commenting in jest, its not like I was accusing you of stealing my idea or anything. Dale_FZ1 helped me select this turbo and we went through a hell of a lot of compressor maps and calculations to see how it would go. He's also contributed a hell of a lot of information to a lot of threads like these. I never realised that you had purchased this turbo before me, I simply thought that since you have posted this thread so long after I went this turbo route that you were new to this very decent turbo.

No need to start throwing shit, we're all here for the same thing, and that is decent power and to help each other out.

As for the spacre plate, I put mine there because I had a GT3076 with a 0.7 compressor cover before this current 3037 variant, and to keep all of my plumbing all in the same spot, it was easiest to simply mount the 3037 on the same spacer. The Custom 4inch intake and the pressure side of the turbo lined up perfectly. Saving a lot of time and money I guess.

Robo - Keen to see your Dyno sheet.

Edited by The Mafia
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Congratulations on a good result. You sound very pleased with things. Interesting to hear any alternative views from Mafia who has run both 0.63 and 0.82 IW housings with the same turbo.

You're the only bloke I've heard of who gave reasonable consideration to the Holset HX/HY range. I believe they could be a good thing if only there was SOME technical info available for them. With split pulse housings they should offer the characteristics that Discopotato03 wants. I still suspect though, that the cost:benefit equation is still stacked against a true split pulse system. Any further comment on that I will post in the appropriate thread that has been dormant for some time.

That torque dip between 3700-4500rpm is interesting, and seems to afflict many mechanically stock RB25 engines to some degree. Did your tuner make any comment about it, or have any luck trying to improve it? Actually, your torque curve has something of a saw-tooth appearance - is there more work to do on the ignition mapping? Obviously there is no shortage of torque, but I'd be wanting to see a smoother delivery across the range.

As a road car how do you find this setup? ie. is there sufficient low-load response, or do you feel as though it needs a bit of throttle to make things come alive and get that jet-engine feel?

Edited by Dale FZ1
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The Mafia - sorry I got a bit up on my high horse, its hard not to when you spent a lot of time and effort researching something and someone swoops in and says that its funny seeing people imitate their setup and tell you who to thank for your research.

Congratulations on a good result. You sound very pleased with things. Interesting to hear any alternative views from Mafia who has run both 0.63 and 0.82 IW housings with the same turbo.

You're the only bloke I've heard of who gave reasonable consideration to the Holset HX/HY range. I believe they could be a good thing if only there was SOME technical info available for them. With split pulse housings they should offer the characteristics that Discopotato03 wants. I still suspect though, that the cost:benefit equation is still stacked against a true split pulse system. Any further comment on that I will post in the appropriate thread that has been dormant for some time.

That torque dip between 3700-4500rpm is interesting, and seems to afflict many mechanically stock RB25 engines to some degree. Did your tuner make any comment about it, or have any luck trying to improve it? Actually, your torque curve has something of a saw-tooth appearance - is there more work to do on the ignition mapping? Obviously there is no shortage of torque, but I'd be wanting to see a smoother delivery across the range.

As a road car how do you find this setup? ie. is there sufficient low-load response, or do you feel as though it needs a bit of throttle to make things come alive and get that jet-engine feel?

Cheers man :worship: Yeah it'd be good to hear what Mafia feels about his on the road etc. I personally find it fine, of course its not the same as a stock turbo but as I've alluded to in the past - the stock turbo is ridiculously undersized for a 2.5litre engine. Trying to match that spool is unreasonable on a motor with the happy to rev nature of an RB. Even with full boost at 2500rpm, the fun won't begin until after 3500rpm!

How much throttle do you regard as "a bit"? Anything over 3500rpm and any amount of load will result in the car taking off with quite a bit of vigour. On the way home I discovered that anywhere near half throttle and over 3500rpm in the wet in second equalled no acceleration but lots of wheelspeed. Below 3000rpm and it feels fairly NA, but it starts building pretty nicely after that.

I guess one way of thinking about it is that I reckon with the stock turbo for a good amount of the rev range, you get hardly any difference in behaviour from 50% to full throttle. Thats something that annoyed me, it felt you could get 90% of the cars ability to accelerate by giving <50% throttle in the right situation whether you liked it or not. With the setup I have, the amount of throttle seems to bare far great relation to how hard it picks up - probably where the likening with a jet feel comes in. If you give it 1/4 throttle, it feels like it will give you 1/4 of its effort. 50%, it'll give you half crazy. Full throttle, you best have plenty of budget for spare tires. Does that make sense? I (and the only other person who has driven it so far since the tune) reckon it feels a lot more fun than a stock turbo R33 to drive, got plenty of torque to tottle around with but goes silly as soon as you get past 3500rpm at any real load level.

I didn't really talk with my tuner about the torque dip, didn't really notice it until after the tune. I'll be seeing him tomorrow so might have a chat about it and see what he makes of it - you certainly don't feel it on the road. The waveyness is also very interesting, I noticed Cubes has it as well. After looking over my plots a little more I found that the boost curve has a similar wave through it, I wonder if the internal actuator possibly develops a bit of an oscillation when trying to stabilise at its preset boost level.

In terms of the Holset turbos, there are a few EVOs and Euro cars around the place running them. Its a rather big pain in the proverbial that there is so little info around on them, the assumption often is that they have hugely wide maps and you can't go far wrong but I really like to know what I am getting myself into. I did talk and read quite a bit and found that they certainly seem to get on quite well with petrol motors in the 2-3litre area - one of my mates actually has a Holset HX35 with a 12cm housing for his 1JZGTE and another has an HX40 for his L28ET, both cars are still a work in progress so unfortunately I can't report how they have gone.

Going by the reports I've seen around the place, an HX35 sounds like in a lot of ways it is a bit of an equivalent to a GT3076R - though the actual frame of the turbo is HUGE.

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The waveyness is also very interesting, I noticed Cubes has it as well. After looking over my plots a little more I found that the boost curve has a similar wave through it, I wonder if the internal actuator possibly develops a bit of an oscillation when trying to stabilise at its preset boost level.

I had a look at mine and can't really see a wave. I can see a slight back off in torque as the wastegate cracks open hard at 11psi and slows spool dramatically.

If the slight dips up top are the ones you are talking about then yeah that got HEAPS worse with more boost; lots of unburnt fuel was floating around also which I believe indicates ignition problems or god forbid a little valve float which I doubt.

I pulled the BCPR6E 0.7mm gapped plugs and they appear to be running too hot so I have a set of 7's to go in of the part number of NGK R5671A-7 recommended by a few different people/tuners.

Apparently the R5671A-7's position the spark in a slightly different position which helps prevent it from blowing out. Apart from that my clutch was slipping and on the very last dyno run even on the lower boost levels power was a little over the place; the drive home had the clutch slipping in fourth when making 1bar. Was a strange sensation as initially it wasn't a clean slip but rather a shudder which felt like axle tramp in the second+ gear, later it developed in to a shudder that quickly moved to a flare.

Now I have a new clutch in it she feels noticably quicker so I do suspect that was part of my problem + ignition. :worship:

Time will tell.

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Mafia engine size is irrelevant , lower exhaust manifold pressure is a benefit to any engine under load because it allows them to scavenge that much more effectively . Power out the crankshaft is what you get after all the parasitic losses are taken into account and that includes pumping losses .

Cubes divided manifolds and housings that work properly are much less A/R sensative than single ones so you get the large hot side benefits without the negatives of the same sized SS system .

Yes the wastegate issue again , next time we want the housing and integral gate divided . If I remember I'll take pics of the divided housing with its divided integral wastegate paths that I have . Such a pity that its a T4 flange one of GT40 frame size and in 1.17 A/R - even if it is profiled for a GT35 turbine . Its compressor is the same GT37 56T wheel as a GT3076R ...

One of the American mobs , possibily Precision Turbo is , doing a hybrid turbo made up from A Garrett GT3582R but with a different compressor which may be a Holset . Its 7/14 bladed and claimed by Burscher Racing to have a lower boost threshold than the std 3582R . You can read the thread about it over at EvolutionM.net in the Engine/Turbo/ Drivetrain section . I believe they call it the HTA35R .

One thing I've not gotten to the bottom of is a slight difference in the designations on the GT3076R and GT3037S compressor covers . One has KTT1 on it and the other BSK1 , not at home so can't check which has which . It would be interesting to check the two housings to see if there's any diffuser differences .

Cheers A .

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Yeah I think so also.. But Its due a plug change so I'll drop them in anyway.

+ My coils are shagged. They were missfiring on std boost when I had the std coils so I silicone the suckers up and they have been good since.

If push comes to shove I'll replace them but if I don't have to I wont. :P

I'm hoping the problems aren't related to valve float as the numb nuts down at Milton engine Dev said "32pounds seat pressure for a dohc turbo is really good" :S It should be up around 75pounds.

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I have a question for Lithium about the comparison between using old Ford-style housings and the new GT30 family housing.

Firstly, the graph for the 0.63 EW setup shows a similar trend to the 0.82 IW, and the numbers aren't THAT much different. Admittedly, that was with the EW setup having boost running away to 20psi, while the IW setup has fairly good control with boost evidently dropping. All of which simply points to better design, more efficiency, etc. So from that standpoint the GT30 housing is obviously the right setup.

Secondly, you'd commented that with the EW housings that the larger A/R introduced a certain amount of on-road lag which was beneficial in terms of progressive delivery which was preferable to you.

Question: while the IW setup offers better boost control + more efficient flow leading to better scavenging with same power from less boost, is there any discernable difference between the EW 0.82 housing and the IW GT30 0.82 housing? I don't have any issues with the GT30 being the right housing, more trying to learn what the difference (if any) is through seat of the pants.

Edited by Dale FZ1
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My other question relating to housings goes to Mafia:

I know there was a fair bit of to-and-fro about what was going to be the right turbine A/R for your application. And you have actually tried the 0.63 and 0.82 on your RB25 before settling on the smaller one.

Can you give comment about what felt the best match please?

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well, its hard to make the decision based on a few variables, but I will do my best to explain.

The 0.63 rear felt about 200rpm - 400rpm less laggier than the 0.82. I will refer to them as "bigger" and "smaller".

The BIgger housing felt more lazy coming onto boost, requiring more throttle to get going. And the powercurve was more flat.

The smaller housing comes on relatively hard at 3200rpm in second, and hold that hard feeling all the way to the limiter. Its unreal, as you can see on my dyno. The torque curve is stays at its peak from 3200rpm onwards.

Now thats what I like - a car that hold full torque (give or take 20nm) from early RPM all the way to the limiter. It makes the car feel like a large capacity V8 if the revs are higher than 3,000rpm.

The larger housing I was more progressive, and the pull or kick in the pants wasn't as hard, and ddin't feel "full" until about 3800rpm, due to it coming on a bit, but taking longer to full get to its peak.

Personally, I think you're mad if you don't go the 0.63, its not hard to work out how to drive it with that nice big mofo kick in the pants that KEEPS kicking you in the pants all the way to 7,000rpm.

Hope that didn't look like too much of a ramble.

Dale_FZ1, hurry up and get your ass up here so you can take her for a drive.

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That torque dip between 3700-4500rpm is interesting, and seems to afflict many mechanically stock RB25 engines to some degree.

To be honest i think thats more tuner than anything.

My stock head RB25 had no problems/dips/lumps and it was over 300rwkw with what some would call the 'lowly' PowerFC :)

And also Joel, you know i ran over 350rwkw with stock coils... go buy a set of splitfires you tight ass :)

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To be honest i think thats more tuner than anything.

My stock head RB25 had no problems/dips/lumps and it was over 300rwkw with what some would call the 'lowly' PowerFC :)

And also Joel, you know i ran over 350rwkw with stock coils... go buy a set of splitfires you tight ass :D

On stock ECU and turbo etc my car had the same dip at the same revs.... are you running VCT?

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hey guys

i have some QUESTIONS!

i've been reading a lot about the gt3076r, but i'm after some sort of insight on what i can get out of my RB24DET. it have all supporting mods.

i'm looking for a turbo to make a solid 280-290rwkw and the GT3076r IW seems like the option. I'm interested to find out what specifications i need to obtain this power with as much reponse as possible - i think the .6 front comp cover, 56trim, .63exhaust housing ( IW ) is the option

will this achieve the results i'm after?

am i correct that i have to buy this in 2 seperate parts (as in to get this setup i need to buy the exhaust housing seperately)?

also i have a HKS adjustable actuator still - can i use this? or do i need the garret 1 bar actuator to suit the garret turbo's?

thanks

-Matt

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hey guys

i have some QUESTIONS!

i've been reading a lot about the gt3076r, but i'm after some sort of insight on what i can get out of my RB24DET. it have all supporting mods.

i'm looking for a turbo to make a solid 280-290rwkw and the GT3076r IW seems like the option. I'm interested to find out what specifications i need to obtain this power with as much reponse as possible - i think the .6 front comp cover, 56trim, .63exhaust housing ( IW ) is the option

will this achieve the results i'm after?

am i correct that i have to buy this in 2 seperate parts (as in to get this setup i need to buy the exhaust housing seperately)?

also i have a HKS adjustable actuator still - can i use this? or do i need the garret 1 bar actuator to suit the garret turbo's?

thanks

-Matt

ok easy one.

Go to your turbo shop and tell them you want the 700177-5007 turbo, with the 0.63IW XR6T style rear.

Exactly what mine has. (I'm running 300rwkw on a RB25DET - *My 300rwkw adventures Thread*

Edited by The Mafia
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RB24/RB25 dude, do some reading. Nothing major in terms of difference

I linked in the other thread to Mafia's thread, which goes into the level of detail you require.

If you dont understand it, then your best off talking to a workshop and let them work it out

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