Stock Skyline Turbo Specs Rb20/25/25Neo

[sav man]

Just wondering if anyone knows what the standard specs are for a RB20/25/25NEO turbos? I'm mainly after the A/R sizes. I can only run highflow Nissan turbos for the racing I do

[GTSBoy]

They go smallest to largest, in the order you've listed them.

[AngryRB]

i was told by MTQ that the RB25 exhaust housing was about 0.5A/R , dont quote me but yeah its small.

Edited April 25, 2012 by SliverS2

[Dale FZ1]

None of them are marked with A/R sizes. You would have to cut them up to establish the actual A/R if you needed it.

Factory numbers cast into them do help to identify the engines they mate to. Some time back I closely inspected housings. Their respective R sizes are all good enough as the same, but there is variation in the A (cross sectional area of the gas passage) which is immediately obvious.

RB20 runs unique sized comp housing (to the RB20/25 series) and it is the smallest in the family. It would be the least attractive to high flowing.

RB25/Neo both run the same sized larger comp housing.

RB20/25 both run the same sized smaller turbine

Neo runs the largest turbine, usually referred to as the OP6 (factory number cast into it), and also a shared fitment with the single turbo VG30DET engine.

I ran a GT2871 cartridge into stock RB25 housings, quite a successful unit for road use.

For race/tarmac rally I'd suggest the Neo housings, and consult with Hypergear as to the best impeller combination. Are you required to run an inlet restrictor?

[sav man]

I've currently got a 400hp RB20 highflow, and it doesn't need a restrictor. I'm happy with it, but i'd like a slighly bigger rear housing so I can spin the engine harder. I thought a NEO would probably be too big for a 20? Idealy I'd run a HKS GT-RS if I could

[GTSBoy]

An OP6 housing can be too big for a 20....but people do put plenty bigger turbos than that on 20s. From personal experience of a 20 running a VG30 turbo (OP6 housing of course) it was pretty good.

[R31Nismoid]

I've currently got a 400hp RB20 highflow, and it doesn't need a restrictor. I'm happy with it, but i'd like a slighly bigger rear housing so I can spin the engine harder. I thought a NEO would probably be too big for a 20? Idealy I'd run a HKS GT-RS if I could

How much power roughly are you getting out of it?

Does it fall over at a certain RPM?

[Dale FZ1]

I'd have a good read of the detail in the Kando turbo thread, and pay attention to the comments from Roy as to what has worked for him, and what rpm range it works on his RB20. Have a think about if that's the general result you're chasing, and see if those impeller sizes are workable within the Nissan housings.

Finally I would consult with Hypergear on their product lines to see what they offer. I'd think you'll be surprised what can be done for a reasonably modest outlay, and conform with your rules. The larger OP6 turbine should/would lift the effective rpm ceiling of your torque (ie lift the power), and also the rpm where it starts to make good torque.

Presumably if you have a 400hp rated turbo then there should be the ability to run 280-320rwhp, so I agree with Ash - what does it actually produce, and what sort of different characteristic are you chasing?

[Bsa]

Once wheni was trying to find all this stuff out I came across a thread in gtr Canada of a guy who had worked out the turbine Ar sizes

Rb20 .5

Rb25 .5

Rb25 neo / vg30 op6 .64

Don t quote me on this just found it on google

[sav man]

Currently the car has 258rwkw on E85, the engine realy hits a wall at 7500rpm with 4deg exhaust cam retard, and 8000rpm. Idealy I'd like to spin it to 8500rpm. My thinking is that it will be a combination of rear housing size, and cam timing.

I don't want any more power, the turbo has produced 270rwkw on a different 20 (that I killed), and any extra power will just make the car slower on a rally.

Current turbo specs:

Compressor wheel:

Billet-D, 52 trim

Inducer 51.3mm, Major 71mm.

Turbine:

Cropped back TO3 72 Trim

Major 59mm, Exducer 48.7mm.

[Dale FZ1]

_{i just saw some of your in-car. Better understand what you're doing with it now Go the E85, pretty strong result there! Do you know what spec/size turbine rotor it has?}

_{Presumably you have a few post-event notes and maybe some datalogs that you can review. Agree 100% that there is the potential for a slower point-to-point car by simply chasing more power (ie a higher power number). That's what I was indicating with the comments about raising rpm thresholds - effectively you can end up simply making the same torque but at higher rpm, and be caught out with less drive off the corners simply to have an engine that can hold another 500-1000rpm before it runs out of puff.}

_{As it is, what rpm band are you spinning in during the corner and on exits? How does that sit with the effective torque range of the engine? Does the budget and rules allow you to play with gear or diff ratios?}

_{I do think it's possible to achieve different results with a simple housing change, but maybe the best (ie fastest point to point tarmac car) results would require either complete change of the turbo's rotating bits + a housing change, and/or some different ratios to suit your road-speed range.}

[sav man]

The turbine sizes are above, just in a different colour for some reason?

Idealy i'd like a OP6 housing to match my highflow, so I can back to back test them.

We can change gears and diffs, just needs to fit into the stock housings. I wouldn't want any lower than a 4.3 diff anyway because of the high speed stages.

[discopotato03]

The turbine housing on the RB25s turbo is actually a tad larger than the RB20s one , people think they are the same but if you get the two side by side and use something like open ended spanners as go/no go gauges you can see the difference .

In the interests of looking standard the 25s turbine housing would be a good start and is a direct fit on an RB20s BB turbo . If you had a different turbine it would have to be profile machined to suit .

A far as I know , having seen a few 20/25/VG30BB turbos , the ceramic turbines are dimensionally the same . Aside from the larger turbine housing really the only difference with the VG30BB compared to an RB25 turbo is the compressor wheel which is a little smaller (30 = smaller) .

A .

[Dale FZ1]

The turbine sizes are above, just in a different colour for some reason?

Idealy i'd like a OP6 housing to match my highflow, so I can back to back test them.

We can change gears and diffs, just needs to fit into the stock housings. I wouldn't want any lower than a 4.3 diff anyway because of the high speed stages.

I'm not yet ready to admit I need glasses to read

You've certainly got a decent sized turbine rotor, and the OP6 housing would be an easy enough swap-in proposition once machined to suit. Relatively straightforward, and worth doing before feeling inclined to re-engineer the complete turbocharger or make gear ratio changes.

It could still be the case that the T03 based rotor is not the most efficient of its type, and I would keep an open mind about what size/spec rotors are bing used in those TDO6 units. Blade count and shape can make a massive difference to airflow/restriction, and response. I have found that Kando thread very useful in understanding what approach MHI have used.

[WMDC35]

Try and get hold of a housing to try? I tried .70 twin scroll (now .63 open) on a 25 and the car was such a pig!