Difference between front and rear turbos

[Kaldek]

For those of you which are curious about this, there are differences between the front and rear turbos that stop them from being swapped between the front and rear of the motor, even if you remove the compressor housing.

The differences between the compressor housings are merely the holes tapped in the housing for the wastegate mounts, so this is easily overcome. However the differences in the Centre Housing and Rotating Assembly (CHRA) are not as easily managed. The only difference is that the coolant line return hose mounting point is different, but it is not easily fixed.

You can see from the above image that on the left turbo (rear turbo example) that the upper hole has been tapped and the lower hole has been plugged. On the front turbo this is reversed; the upper hole is plugged and the lower hole is tapped.

 

[jungle]

I think you meant front and REAR turbos!

 

[Kaldek]

I think you meant front and REAR turbos!

Oh. Whoops. Fixed.

 

[wintertidenz]

Those are frost plugs - if I remember rightly the holes are still tapped. You could just remove one plug and install another to convert the CHRA.

 

[Kaldek]

Those are frost plugs - if I remember rightly the holes are still tapped. You could just remove one plug and install another to convert the CHRA.

Did some checks on that. Seems to be that these aren't tapped. I'd be thinking you'd need to bore out the one that's tapped and fit a larger plug to suit the oversize bore.

I'll go check my spare. It's a stuffed turbo anyway (bent inducer fins) so there's no risk.

 

[Kaldek]

Righto I had a look. Threaded holes are evident as the thread is right at the surface. The plugged holes have no evidence of this and whilst I managed to get a tool in there tight it could not be backed out. I figure I'd need to use the old freeze plug removal technique - hit it with a screwdriver to eyelid it and remove with channel locks/locking pliers.

TBH surely if it was a tapped hole they would have used a plug with an allen head in it or something. I suppose you could always do that - knock out the plug, tap the hole and insert a threaded plug.

 

[smohekey]

They're not tapped.

 

[jungle]

Righto I had a look. Threaded holes are evident as the thread is right at the surface. The plugged holes have no evidence of this and whilst I managed to get a tool in there tight it could not be backed out. I figure I'd need to use the old freeze plug removal technique - hit it with a screwdriver to eyelid it and remove with channel locks/locking pliers.

TBH surely if it was a tapped hole they would have used a plug with an allen head in it or something. I suppose you could always do that - knock out the plug, tap the hole and insert a threaded plug.

They aren't tapped. they will need to be. I had this done to mine a few months ago to one of my hi-flows after KInagawa screwed them up

 

[Kaldek]

Some more pictures for reference purposes. Turbo on right (the clean one) is a rear turbo. The dirty one on the left is a front turbo.

 

[naughtika]

ours are TD03L-7G right?

can someone please also confirm if the VR4 (8G) came out with 2 different compressor wheels?

Im lead to believe that there are handful of 9G compressor wheels out there..

I suspect that they came out with the FL Type V VR4's

 

[Kaldek]

ours are TD03L-7G right?

can someone please also confirm if the VR4 (8G) came out with 2 different compressor wheels?

Im lead to believe that there are handful of 9G compressor wheels out there..

I suspect that they came out with the FL Type V VR4's

Is that essentially the start of an idea where you try to squeeze a bigger compressor wheel into the housing to hold boost at high rpm without sacrificing boost threshold rpm?

 

[veegeeta]

Ive also just learnt that the nut on the compressor wheels are different threads one is left hand thread the other is right hand thread. and another thing ive noticed today is i have 2 spare front turbo housings and 1 core fits in 1 housing perfect but compressor wheel scrapes in the other. maybe there is some slight differance in some cases

 

[Kaldek]

The thread direction doesn't make sense, because both the front and rear turbos spin in the same direction. The design of the turbine housing directs the exhaust gases so that both the front and rear tubos rotate clockwise (when viewed from the compressor wheel end).

It's possible what you have there is an actual high flowed turbo with a larger compressor wheel or one of the TD03-9G as mentioned earlier. If you have a vernier caliper I'd be interested in seeing the inducer and exducer measurements for those two turbos.

Read here on how to measure: http://baeturbosystems.com/howtomeasurecompressorandturbinewheels.aspx

 

[veegeeta]

no compressor wheels the same one had a bent shaft. but i do have one lht and one rht that im certain of