Why isn't the torque curve flat?
12-22-2002, 09:21 PM
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Why isn't the torque curve flat?
Everything I have read seems to say that good torque curves should rise rapidly to about peak, stay level for the majority of the rpm range, then drop off. Why does the torque curve for our Z's look like Mt. Everest?
12-22-2002, 09:34 PM
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Well, ideal torque curves are rarely real world torque curves.
There are a lot of considerations in what an engine's torque curve looks like. The VQ35 actually is reasonably flat below the torque peak. Yes, it climbs up to the torque peak, but its still producing more than 85% of its peak torque down at 1500 rpm or so. That's pretty healthy.
The only place the torque curve suffers is beyond the peak. This could be attributed to a number of things, but at this point, everyone but Nissan engineers are guessing. It could be ECU tuning. It could be that the cylinder heads don't flow that well on the top end (small ports are better for bottom end, but hurt top end). The cams could be a bit small for top end power. The list goes on - but again, its a guess until someone flows the heads, measures the cams, gets some inside info on the ECU, etc.
Shawn
There are a lot of considerations in what an engine's torque curve looks like. The VQ35 actually is reasonably flat below the torque peak. Yes, it climbs up to the torque peak, but its still producing more than 85% of its peak torque down at 1500 rpm or so. That's pretty healthy.
The only place the torque curve suffers is beyond the peak. This could be attributed to a number of things, but at this point, everyone but Nissan engineers are guessing. It could be ECU tuning. It could be that the cylinder heads don't flow that well on the top end (small ports are better for bottom end, but hurt top end). The cams could be a bit small for top end power. The list goes on - but again, its a guess until someone flows the heads, measures the cams, gets some inside info on the ECU, etc.
Shawn
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