Holes in fenders...

[slack11]

Reading the rules, they say that the holes can't be any larger than 4" circles, but it also states that a 4" hole saw creates a hole bigger than 4" , hence illegal.....  What does everyone use for this.... Saw that you can buy a 3 7/8" hole saw...  Is that what is used to get as close to 4" without being too large?

[justfreaky]

Measure the outside of the holesaw and I am sure the 3 7/8 saw is pretty darn close.

Steve

[VMS Motorsports]

Look at pictures from the big money race and Nationals, they obviously don't check that too closely, but I personally would go with smaller holes.
I ran 4" holes in the front, and the vibration (from the rough track-dirt) causes the fenders to crack easily. You're probably not going to put 10 4" holes in each fender, but 10 3" ones while maintaining fender strength on these ever thinning fenders may be a good idea.
Just my hillbilly dirt boy opinion

[slack11]

I could see where on dirt that would vibrate these this to pieces if you holed them up too much....  You're right, looking at pics from the lager races, there isn't't a lot left to these fenders behind the wheels on the asphalt guys. Gotta believe they would hold up much better on asphalt than dirt ( until someone takes it off for you.....) looks like I'm gonna give the 3 7/8" a go.....

[IraceLegends77]

I use a 3.5 hole-saw. I have gone to the max but as Jim stated it will crack your fender. The do not check this rule at anywhere I have been though. They will one day when they have an excess of fender though. Anyone remember Dodge City?......

[knoxracing]

The 4" hole is the largest hole. 10 holes max. These guys are going by total cubic inch of a 4" hole, they have longated a smaller hole. You see alot of guys with these types of holes.

[Briz81]

Was at Southern National this weekend and saw these unique fender cuts on the car parked next to us. The kid in this car won by half a straight against some of the best in NC/VA, so maybe they helped.  

[Richie25x]

This is become the common style of holes.

http://sphotos-b.xx.fbcdn.net/hphotos-ash3/540408_419229034779769_519813758_n.jpg

[Briz81]

Is it a matter of aesthetics or does this style of hole have some kind of benefit?

[knoxracing]

If you read the book you can come up from the frame rail 16" and cut a 3" path to the firewall. Thats in addition to the 10 holes.

[knoxracing]

Briz81, its hard to see the picture, I think the 3" cutaway is what they have done.

[Briz81]

Yup, in person there were seven, 2-3 inch tall by 6-8 inch wide cuts from just above the large botom holes by the muffler, to the top arc of the fender.

[justfreaky]

Is it a matter of aesthetics or does this style of hole have some kind of benefit?

The holes, no matter what size or shape, get air into the brakes and engine compartment.

Steve

[NJRacer510]

The way the rule is it's a 4" hole so that means you could cut any shape hole you want as long as the area is equal to or less than a 4" hole. I run 10 holes in both of my fenders and when I went to a race last year it was the first time the official saw this. He came over and asked if he could check my fenders, so he did and after he figure out the area it was less than a 4" hole. He wanted to check because he never saw that before and when you cut a different shape than a "circle" it looks like there is more area removed but really isnt. If you want to use 4" circles then cut them with a 3 7/8" saw which will give you a 4" hole.

Air to the engine and brakes help, that is the main concern but as far as holes go, cut how many and whatever shape you want. Do what you like not what people say is the best, i cut out mine the way i do because I like the way it looks but performance wise its no different than a circle.