Turbine housing size

[ken666]

I'm in the process of building a new turbo for a friend to replace his worn out factory unit, but when we removed the worn out turbo to use the original turbine housing to use on the new setup we put together. I noticed that most of the bolt holes (dump pipe side) are almost stripped out.

The new parts are a billet AR .70 compressor housing, with anti-surge 4" inlet, a new Garret GT3582 dual ball bearing cartridge with a billet wheel fitted.

 

But now we will have to replace the rear turbine housing due to the problems with the threads being so worn, unless drilling and fitting helicoils is a viable option?

If not, a new housing will be sourced.

I have read a few articles about changing the AR size to a smaller volume to help the turbo spool quicker, but I don't have much experience with turbos. I would assume that by doing this, it would restrict flow at higher RPM (and possibly create more heatsoak through the turbo?)

Has anyone experimented with fitting smaller AR.63 or AR.82 housings.

Obviously the wastegate will still be ported to 38mm on the housing to be fitted.

Any help would be greatly appreciated,

Cheers ken    

[k31th]

A smaller exhaust housing isn't the best idea for a 4L motor, but will work reasonably OK for moderate power levels, and as you suggested, it does restrict flow and creates extra waste heat.

 

The 0.7 front cover will introduce lag, too.

 

You can try to get the threads repaired, if they're not reaching the torque required, but yeah, otherwise it needs replacing.

[JETURBO]

Hi Ken

 

the factory fitted 1.06 5 bolt T3 rear housing is a perfect match for a 60+ front wheel with a cover of 0.5-0.7 imho and it’s not much to be gained as the already snappy FG spec turbo is on boost almost instantly with a automatic transmission 

 

something to consider is the fact if you deviate away from factory specs youll need a custom tune to suit so that 0.7 front cover you have selected will already require a tune to suit  

 

rear housings have been an interesting point over the years and expensive at that but I’ve got a new unit that I’ve had a small part in getting made up with constant R&D from myself and if you want I could supply you with one ready to bolt on to any factory CHRA and comes with all required gaskets and seals to do the changeover. Hit me up for one via PM  

 

this is what it looks like and full factory specs but a better desinged port and chamber with a big 39mm flapper 

 

 

[camo86T]

^Have heard good things about these