Turbo Porting

Not much to say here. I did a home porting job during my engine rebuild, worked on the stock TD05/14B, 95 exhaust manifold, and 95 O2 housing. Later I ported the turbine side of my new 20G, and gasket-matched the 95 exhuast manifold runners and the head's exhaust ports. Porting seemed to help the spoolup a LOT on the stock TD05 turbo. NOTE: do NOT try this at home unless you have a heavy-duty air or electric die grinder and carbide bits. It will take HOURS as is. If you try this with a Dremel, you'll be lucky to finish it in days or weeks.

Click on a pic to see the fullsize version.

This is a look at the stock turbo inlet. Dirty as hell, but what do you expect for hot, nasty exhaust gasses going through it all the time? Note the definite step in the input - this is from the ring gasket that aligns the turbo to the exhaust manifold. That ring gasket is thrown away, and the step is ground away.

Starting to grind the turbo inlet on the turbine housing to match the gasket.

This is a look at the step area after grinding. I could have ground it totally away, but it would have taken forever, and it is doubtful it would help that much.

Another view of the inlet. Note I went in pretty deep, about 1 1/2".

A better view of the inlet on a 7cm housing.

Another view of the inlet on a 7cm housing.

Another view of the inlet.

This is a look at the wastegate chamber on the turbo. You can see the wastegate arm and the grinding I did on the chamber above/behind it. This was to enlarge the chamber, and to allow the wastegate arm to pivot back farther, giving me more room to work on the wastegate hole. Note that I did NOT port the turbine exit hole in the turbo - I really didn't want to mess with it, in case porting there HURT flow.

This is a look at the wastegate hole. Note all the nice cracks - ALL stock TD05s will end up with at least 2 of the 3 mine has, due to the design of the turbo. They crack at the thinnest point of the seat, where the air exits to the O2 housing. I enlarged the opening a good bit. Just make sure to leave the hole small enough for the wastegate flapper to seal.

This is a better look at the wastegate chamber on the turbo side, and how far down I ground it when enlarging the chamber to match the gasket. I ground this even deeper and wider on the 7cm housing for the 20G, to match the 95 O2 housing and the gasket between them.

This is the start of grinding a 7cm wastegate chamber for the 20G to match the 95 O2 housing and the gasket between them.

Starting to grind the turbo exit chamber on the turbine housing to match the gasket.
Photo courtesy of Road Race Engineering

Want to know the size differences between a 6cm (060) and 7cm (070) turbine housings? Here they are. You can see that the 7cm inlet has a LOT less material between it and the outside of the housing.
Photo courtesy of Road Race Engineering

Want to know the size differences between a 6cm (060) and 7cm (070) turbine housings? Here they are. You can see that the 7cm outlet is a LOT bigger.
Photo courtesy of Road Race Engineering

Want to know the size differences between a T25 (2G turbo) and 7cm (070) turbine housings? Here they are. Hmmm, now WHY are people upgrading from T25s? ;-)

SO, that's it for porting turbine housings for TD05s. Thanks go to Eric Typpo for input on how to actually do it, and others I can't remember that added little tips.

This document can be reprinted for personal use or reference for your mechanic(s) with no prior permission needed. It can be linked to directly, as long as you have a link to the main VFAQ page of http://www.vfaq.com, though linking to the main page instead is preferred. This document can NOT be reprinted for profit/resale/redistribution of ANY type without expressed WRITTEN permission from me in advance. Bulk copying of this document onto your web site without prior permission will not be tolerated, link to it instead.
Last modified: Aug 28, 1997
Copyright 1997, Tom Stangl
VFAQ.COM, http://www.vfaq.com
talonts