Thai,

Those bumper vents were very nicely done

What did you use to cut and finish the vents?

 

I ended up doing the same as HONDAF1

 

i used a razor and score it several times through the paint and plastic, then use the rotor zip to cup the middle and bend the plastic back and use the razor to cut it off completely. kinda like cutting drywall, cut one side brake then cut back side. then i use a file the smooth out the rest. some touch up paint and it's done

 

wow... really nice work man!

 

I can't cut holes nor add a diffuser in my class but My plan was to make an abnormally large muffler that happens to be shapped similar to a diffuser and make it out of paper thin metal so it won't weigh much. The stock exhaust takes up a lot of the "parachut" back there.

 

^That's why many cars use the satchel type muffler canister, better underbody air flow.

 

Dipstick (Mike Tsay) also has a cut rear bumper, but his cut is not as aggressive as Jim Tway's.

He also has extensive track experience.

 

some good info here.

I was thinking about what racecars vent out their rear bumper and I couldn't think of any.
Then I was watching ginetta racecars and noticed they have a huge rear wheel arch vent:



These are custom built racecars so that won't just be for show

 

granted, this is coming from the civic crowd... and I haven't really looked behind the rear bumper cover much...BUT... isn't there a gas tank and a bumper support right behind the rear bumper, which would negate any reason for the holes?

Meaning, isn't the tank and bumper support right behind the rear cover so that air doesn't get "trapped" there anyways? I can see a benefit of venting near the wheel wells...

 

i think a lot of these racecars have full flat underpanels that reach all the way to the bumper (at least that's what i saw last time i saw one of those flip in the air on TV). then the underpanels end in a diffuser. so, no air would ever reach that bumper cover anyway.