Tuesday

10 Early Season Power Tips



10 Early Season Power Tips

By Don Terrill (c) - www.RacingSecrets.com

It's your first time out this year and you're not happy with the results - Your car feels short on power. At this point most racers will go on a witch hunt to find the one item causing the entire shortfall. Rarely is this the case, more often it's 10 little things adding up to one big problem. Here are 10 I see over and over:

(1) Ignition Timing
Some engines are very touchy to ignition timing - I've seen 2 degrees too little cost 10hp or more and 2 degrees too much cost over 30 hp. An engine or chassis dyno is the best way to find the sweet spot. If that's not an option, learn how to read spark plugs.

(2) Air/Fuel Mixture
If you're still running out of the box jetting on your carburetor, odds are it's fat and costing you power. You can't blame the carb manufacturers for wanting to play it safe and avoid a mass of angry customers who race at sea level in 40 degree (f) weather. Learning how to read plugs is critical to getting it right, but most applications can benefit from going leaner.

(3) Gasoline Mix
I can't even remember the last time I ran gas straight out of the drum/pump. The trick is getting as much oxygen content in the gas as possible with just enough octane to stay out of detonation. Less than max compression engines have the most to gain from getting the fuel mix just right. If you're brave enough and the rules allow it, you can try some of the additives meant to boost oxygen. Depending on the amount oxygen added, you may need to re-jet.

(4) Forced Air
This is not the time to consider a blower or turbo charger, but what about a hood scoop or cowl? For a forward facing hood scoop make sure it's high enough to catch the positive pressure coming off the front of the car. A rear facing cowl hood makes it a lot tougher to find and capture that positive pressure - testing with a manometer will help. With either setup, make sure you've got a tight fitting air pan or your efforts will be for naught. Also, if the car slows down when you seal the air pan, your scoop/cowl is in the wrong spot.

(5) Cold Air
You can easily find 10 hp for every 10 degrees (f) lower you can make the air going into the engine. A hood scoop or cowl is best, but if you're forced to pull air from under the hood, there are still some things you can do: (1) Create a "Cold Air Kit" that pulls air from in front and to the side of the radiator. (2) Paint the top of your hood white to stop the sun from adding to the problem.

(6) Oil Volume
On a wet sump engine you lose approximately 10 hp for each additional quart of oil you run, so stop letting oil pan manufacturers dictate how much oil you run - nobody needs 12 quarts of oil. On a dry sump engine the oil level in the pan is controlled by the scavenge side of the pump, so to keep the level as low as possible consider more stages and bigger hoses.

(7) Oil Pressure
You can lose as much as 5 hp for each additional 10 psi of oil pressure you run. You lower it at your own risk, but I've seen engines making over 700 hp run fine on less than 40 psi. For dry sump engines it's an easy adjustment, for wet you'll have to decide if it's worth the effort.

(8) Oil Type & Weight
The debate was over a long time ago - synthetic oils do free up power - You can expect 5 to 10 horsepower when switching from mineral based oils. Weight should be matched to rod/main bearing clearance and the temperature the oil runs at - the more the clearance or the higher the temperature, the "thicker" the oil required.

(9) Shift Points
It cost nothing to make sure you're shifting at the right rpm. If you have dyno numbers, try a fuzz over peak power and test from there. Of course you can always use your internal dyno - our ability to feel g-force - It's crude, but better than nothing. Here's a clue: If you feel pushed back in the seat immediately after a shift, you were late - which is a lot worse than being early.

(10) Gear Ratio
Ignoring traction or longevity issues, the majority of cars don't have enough gear ratio. Drag racing and short track stock cars should top out well over peak power. Big track stock cars or any type of racing where you spend a lot of time at one rpm should hang closer to peak power.

Want to send off a nasty email about how wrong I am? Well, first read this and then write your own article.