HomeSite IndexSearch Logo



Sport Compact Car - November '98

Technobabble: Spreadsheet Bench Racing

By Dave Coleman

[Put into HTML format by Mike Mager]

This all started when Contributing Nissan Guy Mike Kojima included a comparison to the Integra Type R in his Project 200SX SE-R story this month (click here). Remembering that Oscar Jackson of Jackson Racing had just purchased a Type R and that he dynos everything he sees, I called him up and asked to see the dyno results from when his car was still stock (a state it was in for scarcely a week).

Realistically, our thoroughly massaged 2050-cc SR20 engine should be more than able to hold its own against the not-quite-as-thoroughly massaged 1797-cc B18 in the Type R, but things don't always work out as they should when you are up against the unusually-good Integra engine. Luckily for our side, the results came out pretty strongly in the SE-R's favor. Comparing both engines on the dyno peak power is about the same, but the SE-R makes a lot more power than the Type R at just about every point on the powerband because it makes all its power at a lower rpm. Also, since torque is a function of horsepower and rpm, and making power at a lower rpm means making more torque, the SE-R's torque curve is in a whole different league than the Type R's.

nov01_small.jpg (16590 bytes)But does this advantage on the dyno really translate to an advantage on the street? The Type R has much shorter gearing than the SE-R, so if you look at power versus speed, the SE-R's advantage might go away. Looking at the same problem another way, you could look at torque versus speed. Torque is multiplied by whatever gear ratio the transmission is in, so the shorter gearing of the Type R would elevate the torque curve more than the SE-R's, perhaps making them an even match.

To be sure, I dumped both car's dyno results into a spreadsheet and went to work. The SE-R and Type R, it turns out, are virtually identical in weight, weighing in at 2,586 pounds for the SE-R and 2,600 pounds for the Type R. Given the variations in other factors like driver weight, the amount of gas on board and how many groceries are in the trunk, we might as well assume the cars weigh exactly the same amount. The SE-R's 14-pound advantage could easily go away if the Nissan driver forgot to remove that bushel of radishes from the trunk.

Both cars also come with 195/55-15 tires, so they both have he same rolling diameter on the drive wheels. On either car, 14.3 rpm at the wheel is equal to one mph. Since both cars weigh the same, both have front-wheel drive with limited slip differentials and both have very similar aerodynamic drag we should be able to determine which is faster simply by looking at power versus speed.

Looking at the power versus speed chart here, you can see that the Type R's gearing did bring the power peaks much closer together, but not enough to negate the SE-R's advantage. The broader powerband of the SE-R helps to keep the Nissan in front in power everywhere except for a few mph where the Type R is able to hold on to first gear longer (because of its higher redline). Beyond 80 mph, the SE-R's broad powerband is woven into a high plateau by the well-spaced third, fourth, and fifth gears.

Another interesting point revealed by this chart is how close together the shift points are. Considering that the SE-R comes with a broad powerband that peaks at a mild 140 hp, and pulls to 7000 rpm, and the Type R comes with a peaky 195 hp while pulling to 8400 rpm, it is surprising to see the shift points line up almost exactly. The second-to-third shift makes sense--both cars make it to just about 63 mph in second, eliminating the need for a 2-3 shift in either a 0 to 60 mph or 0 to 100 kph run--but the rest are surprisingly close for such dissimilar powerbands.

Reprinted with Permission