Turbo Sizes On Stock Skylines

[123456]

K so just for my own knowledge can some one give me the turbo sizes on the following

Stock rb20det turbo (t25?)

Stock rb25det turbo (t28?)

Stock rb25det neo/r34 turbo (would it be like a t28/30 because of the larger rear housing?)

Thanks, i did try searching but all i found was the rb20det size and i already knew that

[paulr33]

stock rb20 = t3/t25 (smallest)

stock rb25 = t3/t25 (medium)

stock rb25 neo = vg30 size (large)

stock rb30et = t3/t25 (not sure, large i think)

smallest = somewhere near 0.45a/r maybe?

medium = 0/50 a/r ish ?

large = 0.55 a/r ish ?

t28 is found on the sr20 (silvia, gtir, 200sx, 180sx)

[123456]

what correlation does the "t25" have to turbine/housing size? Sorry bout all the questions just stuff i've wondered and never asked,

[paulr33]

none whatsoever i dont think, the t25 i am pretty sure referes the flange option, which is the connecting plate to the manifold.

ie: an rb30et with a t25 flange should plonk on the stock skyline t25 manifold with no problems (dumps, exhaust aside etc)

[paulr33]

A/R

A/R describes a geometric characteristic of all compressor and turbine housings. It is defined as the inlet cross-sectional area divided by the radius from the turbo centerline to the centroid of that area.

* Compressor A/R - Compressor performance is largely insensitive to changes in A/R, but generally larger A/R housings are used to optimize the performance for low boost applications, and smaller housings are used for high boost applications. Usually there are not A/R options available for compressor housings.

* Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing. Turbine A/R is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel, causing the wheel to spin faster at lower engine RPMs giving a quicker boost rise. This will also tend to increase exhaust backpressure and reduce the max power at high RPM. Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise, but the lower backpressure will give better high RPM power. When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband.

[123456]

Ahh ok thanks, that helped alot, so the best way of identifying turboes is by there A/R i guess, unless it's a branded turbo like a 2530 or something, cheers

[discopotato03]

The std turbos on 90's era RWD Skylines were a Nissan/Hitachi ceramic turbined ball bearing series . They have a "T3" style mounting flange and from memory the compressor backplate diametre is almost the same as Garrett T3 . I think the water coolant banjo bolt thread is the same size as Garret water cooled T3/small shaft T4 cores .

Basically they used small/med/large sized exhaust housings for 2 , 2.5 , 3L sized engines and their respective exhaust gas flow requirements . The turbines were all the same size . Note some R34 RB25DET's used the larger 3L exhaust housing . The compressor housing as you would expect is smallest on RB20 DET's , the largest was RB25DET and the VG30 just a tad smaller than RB25's . You can easily tell the RB25 and VG30 types because they have "Nissan" cast into them in bold block lettering . The RB20 is a more crude style casting and the aluminium more of a silver than a grey colour . The size of the three bolt comp housing outlet is smaller on the RB20 turbo than 25 or VG 30 type . The VG30 type has a straight barb type adapter fitted here whilst the RB25 ones have a 90 degree elbow fitted to theirs . I can't remember what the RB20 type had .

Some people have found a Garrett type comp housing on one variation of the R34 GTT but have not seen this type myself .

Commode VLT's use a small turbine series version of Garretts watercooled T3 bush bearing turbo with Nissan compressor and turbine housings . These have the same T3 mounting flange .

T28 is different again with smaller shaft and bearings/cartridge , is available in bush or ball bearing though the BB types generally have "GT" series compressor and turbine wheels . T25 was a slightly smaller wheel housing variation of the T28 theme . T2/T25/T28 are of the same family core wise and generally use the T2/25/28 mounting flange though there are some T3 flanged turbine (exhaust) housings out there ie from HKS .

The GT25 BB centre section is virtually the same shaft and bearing wise from GT2554R right throught to GT3582R , this last one is slightly larger on the compressor end of the turbine shaft . These can have T2/25/28 flange or T3 depending on who made the turbine housing to suite which application . ATP even now do a T4 flanged housing for the GT3582R .

Lots of variations , cheers A .

Edited January 7, 2007 by discopotato03

[smurf80]

stock rb20 = t3/t25 (smallest)

stock rb25 = t3/t25 (medium)

stock rb25 neo = vg30 size (large)

stock rb30et = t3/t25 (not sure, large i think)

smallest = somewhere near 0.45a/r maybe?

medium = 0/50 a/r ish ?

large = 0.55 a/r ish ?

t28 is found on the sr20 (silvia, gtir, 200sx, 180sx)

Not quite correct there. CA silvias use T25's and SR silvia's use T25g turbos. T28 turbos didnt come in till the S14. Gtir did however get a T28 with a larger rear housing that was the biggest untill the S15 T28 came out.

Cheers

Chris

[123456]

Whoa thanks disco bet that took a while to write up, but damn helpful, cheers mate

[discopotato03]

There is a huge range of Garrett factory T2/25/28 turbos and many of their own hybrids . They were developed because Garrett felt that the ageing T3 had more rotating group innertia than they wanted and the unit was a little bulky for small engine applications . The writing is on the wall when you have .36 A/R exhaust housings to get a turbo going .

They gained a little with the smaller diametre turbine shaft and bush bearings which have less oil shear drag . Innitially they were a bitch of a thing because Garret refused to sell rebuild kits for them and you could only buy cartridges , sound like the BB scenerio ?

Too lazy to look it up but the Pulsar GTiR's T28 was an odd ball specific to that engine/car . Its turbine was 79T from memory and the turbine housing .86A/R . I have a feeling that the compressor is T3 series and its housing a face lifted TO4B . The rally peoply didn't really like them because they were too laggy - amongst many of that cars other insurmountable weight distribution/cooling/body flexing etc problems . It was very likely the beginnings of what became the DP GT2860RS turbocharger .

Edited January 7, 2007 by discopotato03

[123456]

Hmm, methinks i'll bookmark this page so tomorrow when i've forgotten everything i've read today it's easy to find

thx dudes