SupraSport in Haarlem, Netherlands has just finished work on their billet 2JZ head prototype. The company has taken the best parts from Toyota’s VVT-i and Honda’s VTEC technology and combined them into one head. The head comes with two camshaft profiles, a mild 245° duration and 8.25 mm lift for cruising and an aggressive 300° duration and 13.25 mm lift for high RPM and boost. This gives your 2JZ the best of both worlds, good fuel economy and crazy power when you want it. The company will also offer either fixed gears or dual VVT-i with a 2JZ VVT-i intake and 3S-GE BEAMS exhaust. Another nice feature is the ability to adjust valve lash with a screw driver and 10 mm wrench thanks to K20 rockers. SupraSport estimates a complete head will cost about $15K.
If you really want overkill then add a billet 2JZ block by Mazworx and you have yourself one really mean inline-six. Fitzpatrick Racing will soon be pushing 100 psi of boost on their billet block.
Source: SupraSport FB post and SupraSport.nl (more photos)
What is pictured is a single cylinder mock-up (as in, “not part of an engine”), the actual casting doesn’t exist in finished form as yet. A flow bench test is not a reliable predictor of port efficiency under high boost conditions – the density, and how it affects the boundary layer, Poiseville, turbulence etc. are nothing like linear vs. light vacuum flow. I think that some variant of CFD may prove useful, but if it’s being used (and it’s very expensive and slow) it’s kept secret so far.
It also replaces those stupid buckets (common automotive use since 1948 – in fact many engines use the same bucket dimensions as the original Jaguar 3.4 DOHC) with a great new idea: rocker arms! You know, what SOHC and VVTi (boo!) still have, and DOHC (yay!) gets rid of?
I agree that dual variable makes for a nice taxi engine, but that’s not why people spend $15,000 on a GTE.
The rocker arms reduce (not increase) the maximum stable valve train RPM by increasing reciprocating mass (as does larger and presumably heavier valves, unless the laws of physics have been suspended).
The wider included valve angle (stem-to-stem in cross-section) may increase VE at speed, or not. Many pent roof engines have been built with included angles from 20 degrees to 90 degrees, and you won’t know whether it works until you build one.
There are many L6 engines with larger ports and valves that produce far less boosted power than the conventional (non-VVTi) GTE head, so it’s not a “given”.