RHB52 possibilities for EA82T engines .
Posted: Mon Apr 28, 2008 12:54 pm
Epic alert , you have been warned
I'm putting time into RHB52 research because amongst the Subaru EA82 and EJ20 versions (or their components) will be a couple of combinations that do the job a bit better depending on the engines state of tune - ie how much say you have in breathing and fueling/ignition timing .
Before people ask I'm looking at this turbo family first because there is a fairly wide range of compressor wheel/housing combinations and the things are common read cheapish .
Its handy that the water cooled ones look like they use similar or same water and oil plumbing and that makes fitting the easy with std parts - if that's the case .
Most of the single scroll single turbo Subaru's use the EJ type up and down pipe flanges so the unique EA82T ones have to go and a good thing too .
Ok to the facts as I know them so far - feel free to correct .
The RHB52's that would be most suitable at this stage are from early EJ20 turbo Liberty/Legacy so that makes them smallest to largest compressor wise VF11 , VF10 , VF8 and VF12 .
The numbers I've seen quoted for compressors so far are -
Type ......Inducer ..... Exducer
VJ20 ...... 36.5 ........ 52.5
VF11 ...... 37.5 ........ 52.5
VF10 ...... 39.5 ........ 56.0
VF12 ...... 44.5 ........ 56.0
There must be a wide range of compressor wheels for these turbos but these at least seem available .
Depending on what the std EA82 turbo has that first one VJ20 may be a good starting place . Also note that the turbo's center housing has an integral backplate so it has to match the major or exducer size of the compressor wheel ie ~ 52 or 56mm .
Turbine wise there doesn't seam to be much info at a glance - though the spy's are looking .
Gee tells me that some people have used a slightly larger turbo in the std EA82T's exhaust housing which would mean that the std CPU sized "fan" would not have to spin as fast to move the air - less charge heating . Since it's a drop in mod it's turbine must be the same as the 82's VF2/VF4 or it wouldn't fit and work . If anyone knows which turbo this is (or what car it's from) it could be handy - maybe .
Turbine housing sizes , I have seen mention of P15 P18 and P20 for the VF11/10/8/12 turbos so fingers crossed we'll have a few to experiment with to move the boost threshold around .
I don't know how true it is but some people say that to convert "P" numbers to an A/R or area radius ratio figure like Garrett uses divide the P number into 25.4 ie 20 divide 25.4 = 0.79 A/R . Hope its true - if it is it equates to approximately 0.60/0.70/0.80 for P15/18/20 .
Anyone know the P number on a std EA82 exhaust housing or can check for me ?
So lastly , for now , the big gun in the pack is the manual Liberty RS Turbo's VF12 and I get the feeling that its a little big for the EA82's 1800cc's and inferior heads .
The VF10 and 11 are said to be similar sized and trim turbines BUT the VF10's has 9 blades where the VF11 has 10 blades .
This is significant because when an otherwise identical turbine has less blades the exhaust gas flow through it is less restricted because the gaps between the blades has opened up . Also less blades means less mass or lower polar moment of inertia - less to have to accelerate .
I can hear the snores from here , cheers A .
I'm putting time into RHB52 research because amongst the Subaru EA82 and EJ20 versions (or their components) will be a couple of combinations that do the job a bit better depending on the engines state of tune - ie how much say you have in breathing and fueling/ignition timing .
Before people ask I'm looking at this turbo family first because there is a fairly wide range of compressor wheel/housing combinations and the things are common read cheapish .
Its handy that the water cooled ones look like they use similar or same water and oil plumbing and that makes fitting the easy with std parts - if that's the case .
Most of the single scroll single turbo Subaru's use the EJ type up and down pipe flanges so the unique EA82T ones have to go and a good thing too .
Ok to the facts as I know them so far - feel free to correct .
The RHB52's that would be most suitable at this stage are from early EJ20 turbo Liberty/Legacy so that makes them smallest to largest compressor wise VF11 , VF10 , VF8 and VF12 .
The numbers I've seen quoted for compressors so far are -
Type ......Inducer ..... Exducer
VJ20 ...... 36.5 ........ 52.5
VF11 ...... 37.5 ........ 52.5
VF10 ...... 39.5 ........ 56.0
VF12 ...... 44.5 ........ 56.0
There must be a wide range of compressor wheels for these turbos but these at least seem available .
Depending on what the std EA82 turbo has that first one VJ20 may be a good starting place . Also note that the turbo's center housing has an integral backplate so it has to match the major or exducer size of the compressor wheel ie ~ 52 or 56mm .
Turbine wise there doesn't seam to be much info at a glance - though the spy's are looking .
Gee tells me that some people have used a slightly larger turbo in the std EA82T's exhaust housing which would mean that the std CPU sized "fan" would not have to spin as fast to move the air - less charge heating . Since it's a drop in mod it's turbine must be the same as the 82's VF2/VF4 or it wouldn't fit and work . If anyone knows which turbo this is (or what car it's from) it could be handy - maybe .
Turbine housing sizes , I have seen mention of P15 P18 and P20 for the VF11/10/8/12 turbos so fingers crossed we'll have a few to experiment with to move the boost threshold around .
I don't know how true it is but some people say that to convert "P" numbers to an A/R or area radius ratio figure like Garrett uses divide the P number into 25.4 ie 20 divide 25.4 = 0.79 A/R . Hope its true - if it is it equates to approximately 0.60/0.70/0.80 for P15/18/20 .
Anyone know the P number on a std EA82 exhaust housing or can check for me ?
So lastly , for now , the big gun in the pack is the manual Liberty RS Turbo's VF12 and I get the feeling that its a little big for the EA82's 1800cc's and inferior heads .
The VF10 and 11 are said to be similar sized and trim turbines BUT the VF10's has 9 blades where the VF11 has 10 blades .
This is significant because when an otherwise identical turbine has less blades the exhaust gas flow through it is less restricted because the gaps between the blades has opened up . Also less blades means less mass or lower polar moment of inertia - less to have to accelerate .
I can hear the snores from here , cheers A .