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Numbers Game

March 24 2008 at 7:41 AM

Steve Hoelscher 

Response to Engine Lottery results...

While the peak numbers for Pat's motor may not be impressive on paper, the thing that most people really don't understand about dyno sheets is; "the area under the curve". I don't recall having seen a SOHC dyno sheet with a torque curve that flat, or with that much torque that low in the PRM range.

My DSP motor pulled like a train from 3000 rpm. While my DSP motor made significantly more peak torque, Pat's has more area under the curve. That is, it has more power available, more of the time.

My DSP motor made peak torque at 4250 rpm but the curve had a significan arch. It climbed steeply from 2500 rpm to the platue between 3500 and 4700, then fell off. Pat's curve is virtually flat.

The effect on daily driving is significant. It will have more than 90% of its peak torque available any time you step on the throttle. That translates to an effortless feeling. The car never seems to be working hard in normal driving. Nor does the driver have to work to keep up in traffic. Step on the throttle and the car accelerates.

Its my opinion that the low peak numbers are the result of the use of the OE AFM, intake and exhaust manifolds. These three components limit peak flow and therefore the peak horserpower and torque numbers. The side benefit is the very good low rpm torque numbers. I would imagine that a low restriction intake and exhaust would generate much more impressive numbers.

Despite the low numbers, I think Pat will be very happy with his new motor.


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