Andy Ewings

I am just converting my Grp N WRX over to Grp A, I have now got a HKS front mount intercooler kit, but need some advice about what Turbo to use, I am already using GEMS management, any other advice would be great, I.E pistons etc.

Andy

Jaay

Sorry for no info,

But that sounds a toptastic project.

Let us know how you get on when its done, in fact let us know as you go.

Andy Ewings

Will do, I`m just finishing my new shell at the moment and getting all the parts together!

Andy

Scooby Racer

The homologated turbo for the Impreza GpA is a VF15 IHI unit. Rare as hen's teeth though. Ideally you'll need to change :- Rods, pistons, bearings, head gasket (fit steel shim version). The crank should be ok but they're not that expensive anyway to replace every other rebuild for example.
I suggest that you speak to someone at Bill Gwynne Motorsport as they do a lot of work with this spec of car/engine.

Pete Croney

Andy

You may want to fit a late inlet manifold so you can use a front feed turbo, as a minimum.

Other manifold options are turning the whole thing 180 deg which gives a shorter feed from the front mount ic.

Or you can rotate the turbo round and feed it from the side of the inlet manifold.

IIRC, Omega make the low compression pistons and try Farndon for the rods and crank.

My RA had the grp A main bearings fitted. The block is machined away and fatter bigger 3 piece bearings used. These transfer the stresses to a larger area of block.

I also used a works 5.5 litre fully baffled sump.

The mineral gaskets are OK for 1.7 bar but the steel ones come in various thicknesses allowing you to fine tune the compression to where you want it. Be careful not to exceed 2.0 litres!!

Are you going to run active diffs?

Andy Ewings

Thanks guys, I`m getting some good ideas now, I don`t intend to use any active parts as they are stupid money to maintain and forever going wrong, however I would like the later Manifold should anyone have one?

EMS

You are not allowed to run a FMIC on a group A rallycar! This is only allowed as homologated part on a WRC rallycar.

Scooby Racer,

AFAIK the VF23 is the biggest turbo you can use on a group A Scooby. (wasn't it the std. turbo for the STi 3 or 4?)

A VF15 is not homologated for group A.

Mark.

carlos_hiraoka

Any of the turbos homologated for Grp. N use can be used on a Grp. A rally car, but the real Grp. A rally car is not a IHI VF 22,23,24,28,29,30,34 it is different and quite expensive.

Carlos H.

Scooby Racer

Its definately not standard. Thought it was a VF15 but could be wrong. I've got one on my car so I'll take a look at it for some serial numbers if that helps.
If you're running the car as a full, homologated GpA car then there are many things you need to take into consideration. Get a set of homolgation papers for more detail if you've not already got a set.

Scooby Racer

Just taken a look at homologation papers and my car. The GpA papers call it an IHI RHB52. The photos are the same as the one on mine and its got VF15 stamped on it.
Its a fair bit bigger than any of the standard turbos but you could use any of the GpN homolgated units fitted with a 34mm restrictor.

EMS

Turbo´s are always homologated in group A and also valid for group N.

Mark.

stockcar

are you actually running grpA or just "clubman" grpA - if its the second then do what you like - the only time its going to make a difference is if you're doing higher profile events!!!!
alyn - asperformance

EMS

???

stockcar

"????" i take it you need an explanation for 'clubman grpA' -
only the higher profile events in this country run to proper FIA regs., all others allow 'clubman' cars to compete without any homologation!!!!!!!!!!!

Scooby Racer

In any case the VF15 is an overkill if you fit a 34mm restrictor for GpA, as it was originally selected for use with the 38mm restrictor (pre '95 regs).
Any of the other homologated turbos will be more suited to the smaller restrictor and will also have less lag than the VF15.

Andy Ewings

Thanks guys, I had a feeling that would be the case, I`m running a TD05 with a 32mm restictor at the moment, as has been mentioned Clubman Grp A cars can just about do what they want so I will run the FMIC. I have heard they cause lag problems though. Is this true?
I am using GEMS managment with anti -lag .

Scooby Racer

FMIC will cause an increase in lag but nothing you can't get around with a well set up ALS system. The performance gains you'll see from keeping the air temps down will far out weigh any lag increase. TMIC are useless on rally cars where most of the time is spent with the car driving along with a fair bit of yaw angle. Unless that is you drive a Peugeot WRC on tarmac!

stockcar

surely you mean 34mm (32mm grpN), if you dont then get one in - massive difference!!
alyn - as performance

EMS

I see "clubman specs", I live in Holland and we only are alowed to compete with group N and group A cars.

Mark.