the Z24 dyno mule story
Stage 1 - stock carby & engine
The Z24 uses a 2 barrel Hitachi DCR384 carb with vacuum secondary, on a fairly decent intake manifold with big runners. It is a 2.4 litre engine after all. The cross flow head also has good sized ports and valves in standard spec. The only modification is that the original points distributor has been replaced with one of our electronic distributors.
The engine is using the stock (and not too exciting) cast iron exhaust manifold, and stock 2.0” exhaust system with resonator and muffler.
Dyno
run #1
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Stock Z24 block and head ~ 50,000kms since new rings & bearings |
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Electronic distributor running 8deg static advance. |
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Stock Hitachi DCR384 carby and stock air cleaner assembly |
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Stock exhaust manifold and exhaust system. |
The
Navara made 52kW@wheels (70hp) on the dyno
Note:
the air cleaner was removed from the carby to check if there was any difference
in air flow, however the engine made 70hp both with and without the air cleaner,
so no significant restriction.
This is about what we expected. The Z24 has a published factory output of 103hp @ 4800rpm measured at the flywheel. Using a typical figure for drivetrain loss of 20%, and take another 10% due to the engine showing a bit of wear and tear, clagged up mufflers, etc, and you go from 103hp to 70hp easily.
A drivetrain loss of 20% is justified by having the 4WD driveline (bigger diff, larger gearbox, etc). A lot of lighter passenger cars are in the 15%-20% range.
Our target with all this dyno testing is not only to see what difference particular upgrades make, but also to double the original power output with our turbo kit. So we're aiming for 104kW (140hp) @ wheels, which only equates to about 175hp @ flywheel (using 20% drivetrain loss).
But I wouldn't mind pushing it a bit harder and getting more like 200hp @ flywheel, as this should be achievable with our turbo setup. This will also turn the heavy D21 Navara into an enjoyable ride, and you can imagine how much fun going from 103hp to 200hp would be in the sand dunes. 200hp @ flywheel will give us a final target of 160hp @ rear wheels.
The first mod in the search for more power was to try one of our Weber 32/36DGV carby upgrades.
Check out Stage 2 - Weber 32/36DGV carby