Rb25det & Disco Potato Aka 2860rs

[Black_CSR]

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

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

Edited September 26, 2010 by Black_CSR

[-_-StRyDeR-_-]

why would you want your boost setup like that? :s or am i missing something?

[StealthX]

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...

[R31Nismoid]

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.

[Black_CSR]

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 September 26, 2010 by Black_CSR

[R31Nismoid]

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.

[Black_CSR]

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 September 26, 2010 by Black_CSR

[limpus]

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...

[discopotato03]

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 .

[-_-StRyDeR-_-]

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 haha

ps, sorry offtopic

Edited September 26, 2010 by -_-StRyDeR-_-

[scotty nm35]

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?

[JonnoHR31]

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

did that with my standard 25 to get a little more boost. worked well for a free mod, looks a bit bogan tho

[scotty nm35]

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.

[hypergear]

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.

[R31Nismoid]

^^^

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?

[R31Nismoid]

As your post edit now shows - the turbo was experimental?

Seems that one needs to go back to the drawing board

[Black_CSR]

^^^

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?

[discopotato03]

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 .

[scotty nm35]

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?

[hypergear]

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.