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TurboKraft TurboKraft is offline
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Join Date: Mar 2005
Location: Phoenix, AZ
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No, not a bolt-on.

It all looks good, but I have not seen any back-to-back quantitative data, dyno or otherwise.
The author built a twin-turbo conversion on his 964 (employee of BW IIRC), but no comparison info between his current ERF turbos and his prior K16 or K24 turbos.
A local acquaintance has a top-of-the-line R34 Skyline (V-Spec II?) that's had multiple twin turbo configurations -- and Full Race (also local) built his current large ERF turbo layout (YouTube - ‪R34 Skyline GT-R -- Full-Race Twinscroll turbokit / BorgWarner EFR 8374‬‏). He swears it spools faster than his twin Garrett GT turbos *and* makes more power, but no quantitative data to back that up. (None I've seen, anyway, and his car has been on the Dynapack dyno several times prior with the old turbo configurations.)

Still, I'd love to try one out, see how it does on CIS and EFI engines. On paper, these should blow away just about anything else out there. Should simplify the header fabrication and tidy up installation, too.

Funny how everything old is new again -- not just with the ERF, but all turbochargers right now:
- ported shroud compressor covers -- most medium and large frame diesels have used this for decades, ex: Holset upgrade for the common Cummins diesel
- boost recirculation valve integrated into the compressor cover -- anyone remember the 924 Turbo?
- twin scroll housings -- used for K33s and K36s for the 1980s, and I think Ive seen 934 headers with divided flanges and turbine huosings...
- ball bearings with metal cages -- common on the T04-frame ball bearing turbos; ball bearings are hardly new tech
- extended tip compressor wheels -- another Holset feature for some time now
- undercut compressor wheels -- another old trick used by multiple manufacturers to lighten the comp wheel

The ERF just puts it all in one product. And why not? Other than cost (and these aren't cheap) there's no reason not to incorporate all these design features.
Chris Carroll
TurboKraft, Inc.
Tel. 480.969.0911
email: -
Old 07-07-2011, 10:09 AM
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