Turbos Under Investigation


I will be keeping the details of my turbo choice a secret until the car runs.  It was a hard decision between the following (all good choices):

* Max. practical flow values as found on Jeff Lucius' web site (from Jeff's homepage, select Garage and then Turbos)


Goal:  Select a turbo package that will yield 500+ wheel horse power on 104 unleaded (common race fuel available in Detroit).  I want acceptable 1/4 mile performance (at least mid 11s with a 1.80 60ft), excellent third gear pulls (street race from 70 - 120mph), and good performance for extended high speed runs (Silver State Classic - 90 miles averaging 150mph).  Lastly, I'd like the option to upgrade to better performance (more flow without investing in new headers etc.) if necessary with minimal headache.

GT357 (my TD04 pick)

Pros - Easiest to mount, doesn't require any modification to manifolds, Pre-cat eliminators, coolant or oil lines.  But because I'm having custom headers made anyway, this isn't much of a deciding factor.  GT Pro does offer other TD04 turbos with more flow if I felt the need in the future.

Cons - A bit pricey and pushes the limits of the TD04 housing (& the 6cm2 turbine housing) although many are having excellent results.  It's not a ball bearing (see ball bearing pros below).

TD05H - "big" 16G  (my TD05 pick)

Pros - Turbo itself is comparatively cheap and parts are easy to find (popular DSM turbo).  Proven strong performance on the dyno and it is very easy to upgrade to higher flow with a bigger compressor wheel etc.  Turbine housings available in 6, 7, 8, and even 10cm2 sizes.  Only testing will tell which gives the best balance between spool-up and flow on the top end (but the simple fact that there are several to pick from is a bonus).

Cons - Difficult to package.  Requires custom exhaust manifolds / headers along with pre cat eliminators and coolant & oil lines must be modified.  May want to mount rear bank turbo higher than stock location to make it package easier like Joe Cannella's car.  It's not a ball bearing (see ball bearing pros below).

I'd also like to run the intercooler hardpipe on the rear bank similar to stock (compressor discharging up) but requires some mods to the compressor housing.  This could be made even more difficult to package if I decide to use a TD06 compressor housing for its improved efficiency (with the "big" 16G).


Here are some compressor maps for the "big" 16G.  I added my projected engine demand lines on both maps.


IHI RHF 55 (my ball bearing pick), don't confuse with the considerably smaller RHF 5

Pros - Ball bearing, i.e. slightly better spool-up and can stand up to high boost better than a conventional turbo and seal leaks are a thing of the past.

Cons - Expensive and no one in the US can rebuild them.  Turbonetics has the only VSR machine (balance ball bearing assemblies) in the US but they will not touch this turbo.  Current availability requires the unique Subaru style three bolt pattern on the exhaust manifold.  If I wanted to upgrade for more flow later on, it would likely be difficult and expensive.


since August 7th, 2002


Last Updated: 08/08/02 07:50 PM