[Lee]

Originally Posted by Formulabruce

Amazing how DYNO charts start at >> 3500 RPM?? Who DRIVES at 3500 RPM or Higher, ALL the time?
Building an engine to an estimated HP number at some point at high RPM doesn't make sense unless you regularly race it.
455 can have 500 ft lbs of Torque at LOWER rpm than this chart.
There is a TON of Torque left on the table at cruising ranges......

On most engine dynos [which I have limited experience with] there are characteristics about how it functions that make it so it needs to be running at a certain rpm (usually 3500+rpm) for accurate readings. If anyone knows particulars, please share.

Things are different on a chassis dyno. With an automatic transmission, you have to worry about the transmission downshifting. When a car downshifts on the dyno at WOT, it can be a little unnerving!

The car I performed the testing on has a THM350. I've been able to start testing at/below 3000rpm at times, but not consistently without a downshift. Even when I can, the chassis moves around, the carb takes a moment to transition and settle down, etc. making the first few hundred RPM "funny" at times - so it is usually about 3500 before I have "clean" data. With a modern computer-controlled transmission, if you know how to program it, you CAN make a dyno program which will allow testing to start a much lower RPM.

If I have a car with a manual tranny, then I can test at any RPM. I've attached another dyno graph. This is a 79 T/A with an 8.3:1 400, R/A exhaust manifolds, Performer intake and a Qjet. You can see where the secondaries start opening around 2600rpm.

But I do agree with you. I see MOST people throwing away a lot of mid/low-range power in exchange for a little bit of a HP gain. My own car (from the "start at 3500" pulls) has 3.08 gears and a stock torque converter, yet it still has traction problems off the line with 255/60 MT drag radials.