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I have never seen comparison flow tests, but the exhaust ports on the supra head were noticeably much smaller then those on the Z. I was very surprised at how small they were in fact. Of course this doesn't take into account the actual flow capabilities due to their total geometry, but the cross sectional flow area was much smaller. Our intake ports are very similarly sized and shaped to those on the 6G72 from the VR4. Quite a while back, one of the guys over on 3si.org who owned a shop did some engine dyno comparisons between the 2JZ and 6G72. Both with 100% stock longblocks, he used the same medium sized aftermarket turbos bolted up to custom manifolds of the same runner size on each engine. The intercooler, injector size, engine management, etc were all also kept the same for the engine dyno runs. So at low boost levels the 2JZ made slightly better numbers. As soon as the boost was raised to mid and high levels though, the 6G72 began surpassing the numbers produced by the 2JZ. This behavior can be attributed to the higher charge velocity of the smaller ports on the 2JZ dominating the low end of the spectrum, vs the low restriction of the larger 6G72 ports at the higher boost levels. I believe (been a while since I saw the thread) that by the time the ~700 flywheel hp mark was reached the 6G72 was at least 40hp in the lead. This is hardly scientific proof since there are so many other control factors, but this is the best I have seen in terms of comparisons so far. Just thought it was interesting to see what happens when drivetrain and packaging constraints are left out of the equation by using an engine dyno.
www.ipsmotorsports.net
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