Untitled Document

page 3 of 3

ALTERNATIVE FUELS
How about nitrous Pro Mods gaining a tenth or better by pouring it out of the can? Well, apparently it is a possibility. At the recent NHRA U.S. Nationals it was revealed that both Stock and Super Stock racers were using exotic gasolines that would decrease a cars elapsed time anywhere from a tenth to 15-hundredths of a second without any other changes. The only problem is that the gas reportedly costs between $15 and $30 per gallon depending on how much quicker you want to run.

Current IHRA rules don't specify what kind of gasoline Pro Modifieds must run and do allow Ethanol to be used. Ethanol mixes with gasoline and not only increases the amount of available BTU's in the fuel mixture, but also helps prevent detonation. It's a known fact that Robbie Vandergriff experimented with Ethanol when he was running Pro Modifieds and it is rumored that both the Stott brothers and Tommy Grey are trying ethanol/gasoline mixtures.

DRIVETRAIN IMPROVEMENTS
The main problem for nitrous cars seems to be the inability for teams to get the power they are making to the ground. They obviously have the power, as demonstrated when Quain Stott recently went a couple of miles per hour faster on a lap at the eighth-mile than Fred Hahn went when he went the now famous 6.179.

On the surface, there seems to be precious little experimenting in the drivetrain department of Pro Modifieds. According to what the drivers and tuners will say, most nitrous cars are using a 4:10 rear gear and occasionally a 3:89.

The question is, why aren't the nitrous Pro Mod teams doing more experimenting with gear ratios, transmission ratios, clutches, and tires. One drivetrain system that has seen little testing is the transmission. Long ago the Pro Stock racers went to the five-speed transmission. The reason given for the change was to keep their high-winding 500-inch motors in the peak rpm power band for a longer period of time. There is no doubt it works.

A five-speed trans could be an aide for the nitrous cars, but for a different reason. One problem a nitrous car has is that every shift of the trans actuates a solenoid, bringing in another nitrous system. Each time a shift occurs rpms drop and the horsepower and torque developed by the added system shocks the drivetrain, which causes a variety of bad things from unloading the chassis to tire shake.

It has been speculated that a five-speed would smooth out the power and torque curve for a Pro Mod just like it does for a Pro Stocker, plus if IHRA allows unlimited solenoids in 2001 it would mean another system. Before he quit, Bill Nehri of Nova fame was experimenting with a five-speed and other racers have been rumored to be doing so as well. It proved to be a benefit for the supercharged cars.

Staying in the drivetrain area, why aren't teams doing more with the three-disc clutch. A third disc only adds about seven pounds of rotating weight and to the uninitiated it would seem the added surface area could be a benefit, especially with the kind of torque a 700-800 inch motor develops.

Finally, a look around the nitrous pits at an IHRA event indicates that most, if not all, of the cars are running the tried and true Goodyear. Goodyear is a fine tire, but many of the blown cars have switched to Hoosier, including car owner Jim Oddy.

"The Hoosier maintains a wider footprint, stays rounder and I get more runs out of it than the tires I used to run," explained Oddy. "Also when I switched to this tire I picked up ET without changing anything else."

The Hoosier may not work best on a nitrous car, but if it does, it might be the cheapest change to improve performance you can make.

page 3 of 3