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- Sep 9, 2004
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Y’all need to consider just how tight you plan to turn your 1fz.
Stock redline (on an 80 tach) is 5,000 rpm.
Stock displacement is a touch under 4.5l (4476.78cc or 237.19 in^3)
Assuming a VE of 0.8, that’s 9000l/min or about 318 cfm. This is the intake volume.
Straight exhaust tube flows about 115 CFM per square inch. 2.0” 16ga tube will flow about … 318 cfm. 2.5” will flow a bit over 500 cfm. This is more than enough to accommodate the mass of the (burnt and unburnt) fuel and the expansion of the exhaust due to increased temp.
Yes, getting the exhaust tube diameter and primary length can improve scavenging and therefore VE.
Yes, a bit of porting will improve VE.
Yes, forced induction will definitely improve VE.
That fzj40 above is running about 4.7psi of boost, and it was definitely running at sea level in that video (Cartagena, Colombia). Atmospheric pressure at sea level is 14.7 psi, so the supercharger increased the intake volume by about 32% before accounting for the increased intake air temp, but even a 25% increase in effective displacement is HUGE, VE goes up because you’re no longer counting on vacuum to fill the cylinder.
Take a 5.2L stroker, turn it to 6,500 and get the VE up to 1.0 and the intake volume goes to nearly 17,000l/min or 600cfm, and now you’re looking at a 3.0” exhaust, minimum, otherwise back-pressure will rise and VE will drop, so torque drops. So now you run dual exhaust so only half the displacement is in each tube.
I get the race tractor thing. I really do. It’s fun.
But if it’s a daily driver, you’re also unlikely to spending a lot of time anywhere near 5,000 rpm.
You should build a super charged turbo engine, 1FZ or 1HDx variety.
I had one, boost from idle from the SC then compound once the turbo began to spool.
The sound of this (mine was a diesel) is beyond good.
Cheers