Please Help -9 Vs 2560

[Boostage]

Discopotato03 Im not running an RB I have a 1jz with custom manifolds..

Those turbos there I think are oem rb26 turbos which are now sold. I can run any turbo. sr20,stock rb, any upgraded RB turbos pretty much any t25 based turbo. so fitment is not the concern as I dont have my downpipes made yet. and if it help. my compression is close to close to 10.1 the the 2560r here will cost me $1400 shipped for the pair. -9's will cost me $2300 + shipping for the pair. again, either will fit since Its not an RB or a Skyline. however it is a 2.5L inline 6 with ITB's

Considering its going to be like $1000 difference in price I just wanted to make sure its worth getting -9's over what appears to be SIMILAR specs on the MUCH cheaper sr20 s15 turbos

[discopotato03]

Well that changes things a fair bit . Different engine with different manifolds and high mounted . I suppose the pertinent things are the different inlet system and a little less capacity .

My approach would again be to look at how much capacity is driving each turbine and pay a bit more attention to the compressor sides because they can have considerable effects on turbine response .

Now four cylinder engines are different particularly with the one single scroll turbocharger , they have in 2 liter form have four 500cc pots sticking it up the turbine every 180 crankshaft degrees .

A twin turbo (parallel) 2.5 liter six has 1.25 liters and three 417cc pots to feed each turbo with .

These differences are the reasons why parallel twins are smaller and configured differently to four cylinder singles .

I'll go a bit into OE SR20 turbos so you can see the differences . Firstly the -1 OE SR turbo is the S14 variant , the -4 one was the S15 BB variant and is more expensive because of its higher material spec turbine and turbine housing .

Now these SR turbos both use the TB25 turbine because from a gas energy perspective would be the most responsive .

The compressor side uses a 60mm 60 trim GT series wheel in what is basically a Nissan restyled T04B compressor housing . Now something you have to remember is that turbo engines do ALL their breathing through their compressor housing/s so they must pass sufficient air with least restriction to feed the engine in a non boosted state . I believe there is a juggle with having it do this but still be suitable for the compressor wheel/s and air speed when the turbos up and running .

Did you notice how the OE RB26 turbos have what looks to be small (0.42 ?) A/R compressor housings and T3 internally rather than T4 . This is an area where using four cylinder turbos may not pay off on a six like yours .

I know peoplw will say that some of the higher performance GT2860R BB twins intended for GTR's use the larger comp housings and compressors but they are 330+ Hp turbos on engines looking for high rev performance . They also use the largest size and trim turbine which kills any chance of low end squirt .

I'm not really sure what kind of power delivery you want but I tread warily with an unknown quantity like a 1JZ that never had parallel twins or those manifolds standard . I'd research things like the OE BB turbos used on R34 GTR's which from memory were a GT2556R , I just can't remember if their turbines were ceramic or Inconel steel alloy .

There may be the opportunity to buy these turbos second hand but thats always a grey area with turbochargers because its hard to know what sort of lives they've had .

I'm not sure if I've helped you much , I just know that manufacturers spend a lot of money developing these systems and they don't change things for applications like yours for no reason . This is why I'd be wary of using those SR turbos on your engine and look closer at what they do with parallel twins in a factory application like an RB26 .

Cheers A .

[Boostage]

Well that changes things a fair bit . Different engine with different manifolds and high mounted . I suppose the pertinent things are the different inlet system and a little less capacity .

My approach would again be to look at how much capacity is driving each turbine and pay a bit more attention to the compressor sides because they can have considerable effects on turbine response

turbine is technically smaller than the -9 while the compressor is just a little bigger.

2560 turbine=53mm

-9 turbine= 53.9mm

2560 ind/exd=44.5/60.1

-9 ind/exd=44.5/59.4

Biggest difference seems to be the compressor a/r's . -9 is .42 and 2560 is .60

So to break it down, one turbo has one thing bigger or smaller while the other turbo has something else bigger or smaller. and technically they are rated at the same power levels for the same range of engine sizes. so it just appears to me that they will perform pretty close to each other. but I just wanted the feedback of people like you who are obviously smarter than I am.

[shombre]

Terrific discussion! Just a small point - the 1JZ-GTE non-VVTi did in fact come from the factory with twin parallel turbos, unlike the sequential setup on the non-VVTi 2JZ-GTE, but certainly not on those manifolds pictured. So half of this statement - "... tread warily with an unknown quantity like a 1JZ that never had parallel twins or those manifolds standard..." - is true Carry on ...

Edited March 12, 2011 by shombre

[discopotato03]

Boostage I know the numbers may look similar but there is every chance that turbos developed to be responsive in parallel on an I6 were changed because existings ones proved not to be as suitable .

I too once wondered if the slight differences in the -9s compressor was that much different to a 60mm 50 something trim wheel but Garrett and HKS must have thought so because they went to the effort and expense to fit and test that comp wheel .

Just on this there is more to a compressor wheel than its blade count , inducer and exducer diameters . The exducer tip hight (sometimes called tip width) is another variable and it can make a big difference to a compressor wheel/housing combinations performance . If you look at the GT2860RS turbos you notice a difference in this tip height with the versions intended to be used as twins . I'll have to double check but from memory the single turbo SR style GT2860RS uses cartridge number 446179-66 where the other similar unit uses cartridge number 446179-56 . Almost identicical cartridges inc their comp wheels inducer/exducer/trim sizes but the tip height IS different as is the cart'number .

Turbines in the case of the two you mentioned are totally different wheel families not just one kind with a slightly smaller OD option . The TB25 62T is ~ 0.8 mm smaller in the OD than the NS111 53.8mm 62T wheel and its exducer is slightly larger as well being a trim size of 53.8 rather than 53mm . I can't say what the turbine wheels tips heights differences would be though I do know for a fact that NS111 turbines were designed to be lightweight high speed performance turbines where the TB25 is a carry over from the TB25 family and an OE responce kind of thing . The NS111s are 9 bladed vs the TB25s 11 and thin curved trailing edged blades - lighter by the look of them .

Housings on OE parallel twins are generally smaller than those on single units because they have less cylinders and cubic inches trying to kick them into life . I'd say if you had a four litre 6 and wanted low end boost then sure maybe use two SR turbos but you I think have 2.5 litres and only half of that driving each turbo .

I believe it really is a juggle sizing twin parallel turbos because you have to have the turbine/housing combination sized right to spin everything up in the appropriate engine speed ranges , the compressors have to be a good match load and pumping capacity wise for the turbines and the engine , AND you want to avoid excessive turbine inlet pressure and compressor surge .

With so many things to juggle its a lot to hope for that using turbos designed for a different engine configuration will work . Maybe they will and maybe they won't and if they don't you've spent the money and your turbos are "used" so drop in value .

Honestly what I'm trying to get you to avoid is the pain involved in getting it wrong because if you then have to buy the right turbos its expensive particularly with two of them - AND the work involved to fit differently packaged turbochargers .

Anyway as I said I'd err on side of caution with the R34 GTR BB turbos if they have steel turbines or the 707160-9 ones because both are known to respond well twinned on a 2568cc I6 . They are a known quantity rather than a guestimate which if you're unlucky will burn you big time money wise .

Ultimately the decision is yours and its your money at stake . Too late now but another option if you kept the original bush bearing turbos may have been to have bought BB cartridges and had them modify and reuse your old housings .

Again your call , cheers A .