Jump to content
SAU Community

Recommended Posts

Hey Guys just an update on my 2860RS 0.86 A/R Turbo..

The first two Graphs where I made 318RWHP is with the spring of the actuator not adjusted and tightened. That dyno

graph had quite a bit of knocking and pinging on the road so i went for a Re Tune. The 2nd graph where i made 290.1HP is with the

Actuator spring tightened adjusted.., in the process we had to install a new clutch in as it died on the Dyno.

Pretty happy with the results.. it made less peak power but it's definitely faster.. :-)

With the Actuator spring adjusted and tightened.. i manage to hit a Peak boost of 21psi and hold 1Bar of boost as it reaches Redline..

The way the power is delivered and how steep the Power Curve is makes a big difference on the Road.

Discuss :laugh:

P.S. Thanks to Stao from HyperGear for Making this Turbo :-)

post-26455-1285462092_thumb.jpg

post-26455-1285462121_thumb.jpg

post-26455-1285462160_thumb.jpg

post-26455-1285462167_thumb.jpg

Edited by Black_CSR
Link to comment
https://www.sau.com.au/forums/topic/338169-rb25det-disco-potato-aka-2860rs/
Share on other sites

Yeah same, I'm confused as to why you think 21psi falling to 14psi is okay? You're loosing all your precious boost at redline! If you fixed up your boost control and run a flat 21psi, you'd make in the region of 350hp I reckon...

For the record, my car runs a .64 2860rs, 12psi nets me 255 all paw hp. That's not an rb25 yeah, it's a qr25, still 2.5, so my figure's at least somewhere in your ballpark...

1st lot of graphs compared to the 2nd - its a lot better...

However 4000rpm you still only have 140rwkw, for a peak of only 230rwkw on 21psi IMO that is poor.

You'd expect that kinda power delivery from a 600hp turbo - not a 400hp one.

.86/.82 is a bad rear end choice for a start. Any why boost would be nosing over that hard is amazing... Certainly I'd have issues with that.

As an example have a look @ the two graphs below simply taken from the RB25 dyno thread.

180rwkw @ 4100rpm, that is a whopping 40rwkw more than your setup for pretty much the same end result, and less boost as well to boot.

http://www.skylinesaustralia.com/forums/post-a279850-

This next graph... 500-550hp GT30, making 160rwkw @ 4000rpm. 20rwkw more @ 4000/40rwkw more in the top end

http://www.skylinesaustralia.com/forums/post-a288761-

Now my aim was not to bag your setup - simply to highlight there is a pretty big problem.

I'd be investigating the boost control firstly - try get it holding 20psi to redline.

If it wont (even with the gate held shut), then it's just a poor turbo.

Nah it's not going to hold to 21psi @ redline.. this is a similiar turbo to 2530 turbo... but with a 0.86AR.. 2530 usually tapers off when it gets to redline.. n drops down a lot to 9psi..

2530 r known for it's midrange punch not it's peak power.. 2530 will not make 350HP @ da wheels... more like 300HP.

Edited by Black_CSR

You don't have 350hp @ the wheels either mate. So whats the reference to 350rwhp for?

I know what a 2530 is capable of.

And as i linked - a HKS2530/RB25 - is making 10rwkw less @ peak, but 40rwkw more in the midrange than the turbo you have does. 10rwkw is here/nor there. dyno differences.

So basically the 2530 is beating your setup in a huge way.

Like i said, the turbo at this stage appears to have all the lag of a turbo capable of 300rwkw, without the power to back it up.

That is very significant in my view.

The reference of 350HP was a post from "TurboX-trail" saying if i can get it to hold 21psi flat it'll make 350HP..

I'm assuming the HKS2530/RB25 link u gave me is a ball bearing and 0.63 AR???

Edited by Black_CSR

Why won't a 2530 hold 21psi to redline?

Like the rest said...results are pretty dismal...boost control is poor and response is just as bad...either something is wrong with your engine/tune or the turbo isn't performing as promised...

I always wondered if anyone would try a GT2860RS turbo on an RB25DET .

The specs are very similar to a GT2530 and the main difference cartridge wise is the compressor wheel , which is supposedly a slightly more modern design than the 2530 .

I am curious as to how you got the GT2860RS with a 0.86 A/R turbine housing on your RB25 since the turbine housing has the T25/28 mounting flange and the RB25's exhaust manifold is to suit a variation of the T3 pattern . Actually its really more of a Euro T4 pattern for the manifolds twin outlets but the bolt pattern is same as T3 .

There is a bit of history in the RS turbo because it was originally something brewed up by a production engineer at Garrett in the US and used on his Miata/MX5 .

They are probably a better 1800 - 2000cc four cylinder turbo - fewer larger cylinders and the need to breathe and make torque early . They are really better at dealing with high gas flow rates and not super high boost pressures which is why they use biggish housings both sides for at GT2860 sized turbocharger . It means you can pull reasonably big rev on an 1800 and screw a fair bit of timing in to make a broad flat torque line .

The turbine housing ratio is 0.86 A/R and the compressor side usually a T04B in 0.60 A/R .

Now because the RB25 is 25% larger than a 2L four its usually better at making very low rev torque and the 9 CR helps out here too because many turbo fours have their static CR pegged at 8-8.75:1 .

Unless on a very std engine with a std exhaust you possibly need a bit more turbo to make the 25 shine , its just a pity that going up the next increment turbine wise means a KHS turbine housing - GT 2835 Pro S type one .

Anyhow all that aside do you have some sort of adapter to get the turbo on the manifold ?

The only other way I can think of is to use a modified VG30 OP6 turbine housing on that turbo .

Cheers A .

I always wondered if anyone would try a GT2860RS turbo on an RB25DET .

The specs are very similar to a GT2530 and the main difference cartridge wise is the compressor wheel , which is supposedly a slightly more modern design than the 2530 .

I am curious as to how you got the GT2860RS with a 0.86 A/R turbine housing on your RB25 since the turbine housing has the T25/28 mounting flange and the RB25's exhaust manifold is to suit a variation of the T3 pattern . Actually its really more of a Euro T4 pattern for the manifolds twin outlets but the bolt pattern is same as T3 .

There is a bit of history in the RS turbo because it was originally something brewed up by a production engineer at Garrett in the US and used on his Miata/MX5 .

They are probably a better 1800 - 2000cc four cylinder turbo - fewer larger cylinders and the need to breathe and make torque early . They are really better at dealing with high gas flow rates and not super high boost pressures which is why they use biggish housings both sides for at GT2860 sized turbocharger . It means you can pull reasonably big rev on an 1800 and screw a fair bit of timing in to make a broad flat torque line .

The turbine housing ratio is 0.86 A/R and the compressor side usually a T04B in 0.60 A/R .

Now because the RB25 is 25% larger than a 2L four its usually better at making very low rev torque and the 9 CR helps out here too because many turbo fours have their static CR pegged at 8-8.75:1 .

Unless on a very std engine with a std exhaust you possibly need a bit more turbo to make the 25 shine , its just a pity that going up the next increment turbine wise means a KHS turbine housing - GT 2835 Pro S type one .

Anyhow all that aside do you have some sort of adapter to get the turbo on the manifold ?

The only other way I can think of is to use a modified VG30 OP6 turbine housing on that turbo .

Cheers A .

Mate, throughout all the years of reading your replys, you seem to have such a great deal of knowledge about turbo's ect, was just wondering what you do for work?

i believe a few beers and a convo with you and most of us would be information overloaded :P haha

ps, sorry offtopic :D

Edited by -_-StRyDeR-_-

Obviously hypergear modified a stock rear housing, it looks promising. Boost come on a little late for that output but there could be a lot more in it. What did it cost in the end and did he offer you the actuator upgrade?

A stronger wastegate actuator spring will get the boost holding, im in the same boat with my highflow, tapering to 16 at redline.

Im contemplating adding a spring to the outside, been done before?

So if a spring can be added, boost will hold better. I have plenty of springs to try, much better idea than cutting the actuator open I think. Could be made to look "professional" with some nice spring hooks, not that you can see my turbo anyway. :P

You don't have 350hp @ the wheels either mate. So whats the reference to 350rwhp for?

I know what a 2530 is capable of.

And as i linked - a HKS2530/RB25 - is making 10rwkw less @ peak, but 40rwkw more in the midrange than the turbo you have does. 10rwkw is here/nor there. dyno differences.

So basically the 2530 is beating your setup in a huge way.

Like i said, the turbo at this stage appears to have all the lag of a turbo capable of 300rwkw, without the power to back it up.

That is very significant in my view.

^^^

In this case would you call a larger turbo.

http://www.digi-hardware.com/images/dynosh...G363295rwkw.jpg

is making more power every where then your 2530 result:

http://www.skylinesaustralia.com/forums/post-a279850-

On the same dyno same tuner with 80KWs more peek?

Any way, For any 2530s on RB25dets there is no way it can hold 20psi. Reason been is due to the size of its rear housing, and size of the comp wheel. Like disco said the comp wheel side is different to a traditional 2860RS, I've managed to trim the exact wheel spec as the 2530.

This turbo was and sold as an experimental unit, I can make it hold 20psi @ 7000RPMS, how ever I don't think it will make much difference in max power, on the other hand probably make less power due to excessive heat, Its not a high boost turbo. How ever I'm not sure what sort of torque the 2530 has, generally .86 rear housing would had more torque compare to a .64 rear.

Black_CSR: if you don't mind to do further testing I can install a gate controller and a high pressure actuator to see what it does holding 20psi.

^^^

In this case would you call a larger turbo.

http://www.digi-hardware.com/images/dynosh...G363295rwkw.jpg

is making more power every where then your 2530 result:

http://www.skylinesaustralia.com/forums/post-a279850-

On the same dyno same tuner with 80KWs more peek?

Is this the turbo we are talking about here?

I would suspect the answer to be no, in which case - what on earth are you posting it for?

^^^

In this case would you call a larger turbo.

http://www.digi-hardware.com/images/dynosh...G363295rwkw.jpg

is making more power every where then your 2530 result:

http://www.skylinesaustralia.com/forums/post-a279850-

On the same dyno same tuner with 80KWs more peek?

Any way, For any 2530s on RB25dets there is no way it can hold 20psi. Reason been is due to the size of its rear housing, and size of the comp wheel. Like disco said the comp wheel side is different to a traditional 2860RS, I've managed to trim the exact wheel spec as the 2530.

This turbo was and sold as an experimental unit, I can make it hold 20psi @ 7000RPMS, how ever I don't think it will make much difference in max power, on the other hand probably make less power due to excessive heat, Its not a high boost turbo. How ever I'm not sure what sort of torque the 2530 has, generally .86 rear housing would had more torque compare to a .64 rear.

Black_CSR: if you don't mind to do further testing I can install a gate controller and a high pressure actuator to see what it does holding 20psi.

Hey Stao.. i would be interested in ur further testing and gladly would accept.. what do u suggest?

I'm not really sure what the situation is here with the turbine housing , personally I would be very reluctant to profile machine an RB25 Hitachi turbine housing for anything except maybe an RB20 . They are not much bigger internally than the RB20 BB Hitachi's turbine housing and I really think the Z32 BB units OP6 turbine housing would be the minimum I'd use in this situation .

If I'm reading that graph correctly I'm assuming that by trying to hold the wastegate shut chasing high boost numbers the (I assume small RB25 T hsg) is probably strangling the thing and forcing retarded timing to hold off detonation .

You could try running the thing at 12-14 pounds and letting the gate vent some exhaust gas and if possible advance the timing up a bit for more efficient combustion .

Cheers A .

I'm not really sure what the situation is here with the turbine housing , personally I would be very reluctant to profile machine an RB25 Hitachi turbine housing for anything except maybe an RB20 . They are not much bigger internally than the RB20 BB Hitachi's turbine housing and I really think the Z32 BB units OP6 turbine housing would be the minimum I'd use in this situation .

If I'm reading that graph correctly I'm assuming that by trying to hold the wastegate shut chasing high boost numbers the (I assume small RB25 T hsg) is probably strangling the thing and forcing retarded timing to hold off detonation .

You could try running the thing at 12-14 pounds and letting the gate vent some exhaust gas and if possible advance the timing up a bit for more efficient combustion .

Cheers A .

Exactly, this housing is too small for the exhaust wheel, just like mine. Would the same be said if the 98 was replaced with E85 though? My exhaust temps are around 550-600 at the turbo outlet so I think there is room to move.

To the OP, with a username like Black CSR, have you got any plans to run ethanol? :down:

Well I posted the other sheet as it is very possible for a near 300rwkws setup to appears more responsive in power curve as it is done 4th gear with paddle to the floor. Does not mean its got better driving ability in lower gears.

Secondly the torque factory is missing in 2530's dyno reading, I'm really interested to see the torque difference in between the 2x housings. I expect more torque with .86 rear.

Black_CSR: I've got few different profiles in mind. I'm very interested to see what a 2871 52T profile would do in .86 rear housing. Please check PM.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Keen to see the turbosmart data, to date I've only seen negative things in terms of response for them. Very small sample size though.     Hawkins is a big advocate in his videos of the larger rear housings. I managed to make similar power with a lower spec motor on the smaller .8 rear, keeping decentish spool.  The people he works with now are big power cars compared to mine though, mine really is setup to drive around and enjoy.  I don't have any back pressure monitoring though, so couldn't say if its good or bad on my car, just that it does what I want it to do.   Future I want a higher compression more cubes motor to give a bit more bottom end and hopefully the new g35-1150 gets me to the 850 rear comfortably.  But maybe I won't due to exhaust back pressure.
    • No, I refuse to buy their cheap ass crap! I do need to order a bunch of different nuts/bolts to refill my nut/bolt wall though. Maybe you could go for a walk through Bunnings for me? (Or send me some stuff from your work? )   I really struggle to work out how the US standardised to Metric in what the 70s or 80s, and yet, half a century later, there's been little done to actually bring it into fruition. It truly baffles me    On the whole Fastenal thing, I went reading their site (My god they sell a lot of varied stuff!), and it seems like it really depends what store you're near if you can walk in and just grab a few small things, or if that branch is primarily distribution with only a small window of "counter time" available (if at all). That definitely makes it harder, as move locations and it drastically changes your ability for success   For things like your M6x1.0, if you want to work on your own Skyline, and you also have a "home workshop" I'd recommend setting yourself up a small Nut/Bolt wall/section. It doesn't even need to be big at all. Most things depending on the diameter, will be a specific pitch, like the M6x1, M5x0.7 etc. Bigger bolts is mostly 1.5, except for a small number of things and that will come down to torque. From memory bolts for the brake calipers (and other things that need a lot of torque) will end up being a 1.25mm pitch. Save up a few dollars, and order a range of nuts/bolts. If you want to minimise cost a little, buy something like M6 x 40, and M6x70mm (1mm pitch) in both. In addition, buy yourself an M6x1mm thread chaser. That way you have long bolts that you can cut down to size, and then chase the threads out. Funnily enough, I find what I'd pay here for ordering 5 bolts, I can pay about 50% more and you'll get 100 of them.   If that doesn't quite work out due to space / ability to buy plenty up front, then each time you need some bolts, order 100 of what ever you're getting. Put them in clearly marked containers. Over a few years, you'll acquire plenty of different sizes, and will end up ordering less and less. And the cost for 100 bolts won't be much more than you paid for your 5 you needed to order anyway  Just takes a little planning ahead, by investigating what nuts/bolts you'll need, and ordering them before doing the job.     Edit: If it's also primarily for working on just the Skyline, for some reason my brain is screaming that at some point, either Nissan, Nismo, (Or possibly a third party) was selling a "kit" of every nut and bolt in a Skyline, purely for people restoring/rebuilding. It'd likely be quite expensive, but would give you every/any nut/bolt you need for stock/factory things. I'm not sure if it's still available, or even if it actually fully came to market, it's just something niggling in the back of my brain that you could look into further if that sort of thing interested you? (It might have been for the R32 GTR or something specifically too, and not just any Skyline)
    • 90lb/min @ 20psi is wonderful, not so much of a problem with the G35-1050's compressor efficiency (aside from how bad they roll back at higher pressure ratios).  The issue is more to do with the turbine's flow, which is why I'm not sold on going an even higher flowing compressor with the same turbine.  I'd say go back over Motive DVD's testing of the G35 1050 and Hawkins's comments regarding exhaust back pressure issues with it, I'd need to go back but I have in my head he went to the biggest hotside and ended up sacrificing a lot of spool (so it ended up behaving like a bigger turbo) and still had EMAP issues.  I've heard various other experiences along the lines of that. At this stage at least I rate all I've seen about Xonas (for transparency I've not used one directly, but I have spoke plenty with people who have) to have low exhaust restriction for the response they offer for any given setup - basically they allow the engine to breathe, which is good for the engine and makes making power a lot easier.  You arguably don't have to even push quite the same amount of airflow through an engine to make the same power if you don't have the bum plugged up with exhaust gas struggling to escape the engine due to an underflowing turbine.   In terms of reliability, to be fair I've had great luck with Garrett turbos as well - my GT3076R lasted forever, then I sold it and the next owner had no issues, then that car got sold and it was still going strong last I ever heard about it.  The trick is with the old GT-series turbos the compressors etc were no way near as efficient as what we have these days, it was almost hard to push them into severe overspeed situations without having a boost leak or something - and that is what often starts the failure situation.    In terms of your G35 I'm pretty sure you're running yours within sensible limits, something people with Xonas and Precision turbos aren't often so inclined to do.  The "compressor maps" are "Joe blogs ran 45psi through his 6466 so I can do the same" and built their setup to send it to the moon.  I've seen EMAP and compressor speed data where people have actually set that stuff up on Precisions and Xonas which have been run hard and the comp speed numbers are very very exciting at times - like I've seen 76mm Precisions run at rpm that you ideally shouldn't run a G35 1050 lol.   I know people who have run G-series Garretts hard and hard a failure, then replaced them with Pulsar turbos as a cheap "get it going" stop gap with the intent of doing a proper upgrade when THAT fails... and are still running the same thing.   Like anything, ymmv and it's not always to do with the quality or trustworthiness of said product. I've been provided with a bunch of compressor maps for Turbosmart turbos and will update my list based off that, they could prove to interesting reading and an interesting alternative as well.
    • Just cage it, call it a race car, and then fall in love with the chirp chirps through pit area!   Also, this is coming from someone with a completely locked diff...
    • I still have an old R32R left over from when they were a thing in the early 2000's. It was, for its time, done about right. But its time was 20 years ago.  I did try and update it a while back but it was cruelled by a (recommended) muppet of a tuna who couldnt tell his MAP from his TPS. The original spec was: Power FC, 700cc Sards, Nismo pump, 2860-5's, cams (Basically Poncam A's), Z32 AFM's and a half sorted oiling system. Thereabouts 430rwhp irrespective of what was done. So, yeah, very 1990's. I eventually got sick of it not being very refined and bought a Link G4 PNP with some 1000cc Bosch injectors. This was tuned badly and I put the car in the shed for a few years whilst I sulked and went and did other things. Ive come around to the idea of getting it going again so it has a new gearbox installed and some other minor things in the planning. So my questions are, variously (In the context of keeping the Link) What other sensors should I be running eg It has no wideband on it at the moment, nor fuel pressure. $? Is it worth chucking the old ignition system (ignitors etc) for new ignition coils? $2k? Cam/crank angle sensors? Can keep the aircon? $? Anything else? Sorry to launch another what should I do with my car thread but, you know, what should I do with my car? Random photo for historical context.
×
×
  • Create New...