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Turbos on Twin Turbo Subaru Legacy/s


gtlegacy

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I'm not - just saying what I have done :P and it works

worst thing all of us have done is a) Buy a TT and b) think more power is easy/accessible with OEM setup... [vauge point that single is basically only/best upgrade]

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 gtlegacy said:

at the moment i have standard vf20 primary and vf19 secondary which is a bit stif so may be on the way out

would a good upgrade be vf33 and vf32?

what are the differences between them? there isnt much info around for the Twin turbos i know that the vf26-27 are the best for top end just wondering how the vf33 and 32 compare

cheers

Subaru reached a twin turbo zenith with the VF25,VF26 and VF27 turbos.

These turbos all have the same size compressor/turbine wheels.

Primary turbos VF25 and VF26 both thrust/2sleeve bearing turbos with A/Rs of 12 and 14 respectively.

The VF25 was on the auto GTB and the VF26 on the manual.

Prior to this all primary turbos were BB on A/R 16 housings, however to get the spool rate the A/Rs had to be dropped.

Secondary VF27 is a BB turbo on A/R of 18 housing.

Another distinction these turbos had was the 8 blade performance turbine wheels instead of the standard 9 blade for reduced weight (improve spool) and better exhaust flow.

Following on from these turbos were the VF31 and VF32 (both have the same size compressor /9 blade turbine wheel)with a larger compressor wheel exducer than VF25/26/27.

The VF31 primary turbo went back to a BB on A/R 11 turbine. The small A/R housing really reduced its potential, but gave it fantastic spool.

Power Enterprise (PE) noted this and put the VF31 on an original primary turbine housing A/R 16 to generate the PE1016F turbo. The secondary VF32 turbo is BB on A/R 18 housing.PE rebadged the VF32 as the PE1018F to market as a set with PE1016F for earlier twin turbos.

Comparing turbos:

Primary PE1016F>VF26>VF25>VF31>VF33

Secondary PE1018F=VF32=VF27 approx equal, the VF27 may have a slight edge at higher boost.

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Noticed on the weekend that my primary seems to be leaking oil (oil sitting on top, and wisps of smoke from turbo area after a good 2nd gear on/off boost cane up the akatawaras)

So you reckon my best bet for replacement would be a 26/27 combo?

Currently have the 18/19 combo.

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 RSB said:

Noticed on the weekend that my primary seems to be leaking oil (oil sitting on top, and wisps of smoke from turbo area after a good 2nd gear on/off boost cane up the akatawaras)

So you reckon my best bet for replacement would be a 26/27 combo?

Currently have the 18/19 combo.

This would be an excellent upgrade.

Alternatively you could go for VF32 as secondary and if you can get a VF31 swap the turbine housing from your VF18 onto it. This will give the VF31 extended performance --> PE1016F.

PS have the primary turbo wastegate ported within tolerance of the existing flapper. (extra 2-3mm)

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Hey telemekas, I have an auto B4 with the VF31/VF32 setup but wanted to upgrade the primary further as I already ported the compressor discharge but the performance gains are negligible. So your saying a good upgrade requires just changing the VF31 backhousing to that of a VF13/VF18? Is this a simple swap or do I have to carry it to a professional machine shop and also get it rebalanced? Please explain.

If so this sounds like a good bang for the buck. At first I was going to rebuild a TD04 with 15g wheel but its very expensive.

PS Where can I get the turbine housing? they are rare to find.

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 gunhawrtis said:

Hey telemekas, I have an auto B4 with the VF31/VF32 setup but wanted to upgrade the primary further as I already ported the compressor discharge but the performance gains are negligible. So your saying a good upgrade requires just changing the VF31 backhousing to that of a VF13/VF18? Is this a simple swap or do I have to carry it to a professional machine shop and also get it rebalanced? Please explain.

If so this sounds like a good bang for the buck. At first I was going to rebuild a TD04 with 15g wheel but its very expensive.

PS Where can I get the turbine housing? they are rare to find.

The VF31 is on a very restrictive P11 (A/R 11) turbine housing.This would be OK if it was a thrust/sleeve bearing turbo like the VF33 with P11.

This is a BB turbo so it has smaller virtual A/R.That is to say if you put it on a P16 housing, it will spool as fast as thrust/sleeve bearing turbo on P14 housing.Thus the P16 extends the VF31 capability.

P16 housings are on all primary turbos pre VF25/26 ie VF13/16/18/20

It should be a direct swap that you can do yourself. No balancing required. Some of the older turbos ie VF13 have slightly deeper collar seat in the turbine housing.Therefore you may require a heat shield spacer 2mm (heat shield with the centre cut out) to seat a later turbo CHRA. (the turbine wheel will sit too deep in the housing otherwise)

Remember you do have an auto so you will note a degree of initial lag / throttle response with the P16 housing.

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 gtlegacy said:

also i have a question with the larger p16 housing what different will that make? boost a bit later? and a bit harder?

Essentially you are making the turbo more efficient (greater flow at the same boost level) An example of this is with the VF25/26/27 these all run the same size compressor wheel/turbine wheel. At the same PR VF25 flows 370 CFM, VF26 flows 390 CFM and the VF27 flows 400 CFM and the only difference between them is the A/R. 12.14 and 18 respectively. The increasing A/R pushes the hook on the compressor wheel map to the right --> into a more efficient area ie 77%-->85%.

The VF31 and VF32 share the same size wheels with A/Rs of 11 and 18. The VF32 has similar flow to the VF27. Therefore one could speculate that changing the A/R of the VF31 from 11 -->16, the flow change could be 365 --> 395 CFM approx 8% improvement in efficiency.

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Thanks for the info Telemekas. I made a mistake, my current primary is a VF33 not VF31. Will the upgrade still apply to the VF33 ie. changing the turbine housing to a P16?

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 gunhawrtis said:

Thanks for the info Telemekas. I made a mistake, my current primary is a VF33 not VF31. Will the upgrade still apply to the VF33 ie. changing the turbine housing to a P16?

No will not work as the VF33 is a thrust/2sleeve bearing turbo therefore has no virtual A/R like a BB does and it also has a smaller compressor wheel therefore less flow.

Upgrade with TD04 CHRA on the VF33 turbine housing this will match with the bigger VF33 60mm compressor Inducer.

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 gunhawrtis said:

So just bolt up WRX Td04l CHRA to the existing VF33 turbine housing and use existing VF33 compressor cover?

From the VF33 you just need the turbine housing and the wastegate actuator.

The turbine housing will need to be scrolled out or high flowed to take the larger TD04L wheel. Once that is done put the TD04L CHRA onto it and orientate the the original position as the VF33 was in . Install the actuator.

Have the wastegate ported within tolerance of the existing flapper or ideally a larger porting with new bigger flapper

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 gazzy2000']

[quote name='RSB said:

right, so i managed to pick up a 31/32 combo. Can anyone tell me where i can get the wastegate ported in wellington?

/quote]

Hey, was that you that just brought my turbos of TM? LOL

lol, probably!

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Guest boostin
 RSB said:

right, so i managed to pick up a 31/32 combo. Can anyone tell me where i can get the wastegate ported in wellington?

DIY FTW!! A power drill and a grinding stone or burr do the trick!

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heya,

how much heat wrap roughly does it take to do a left hand and a right hand rage downpipe?

kk i found out in chch i bought a ceramic type 50ft roll from silvester v8 for $55 and it wrapped both rage downpipes easily with maybe a 1m-1.5m left over

also japanese race supplies sell the same product

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