[1LE_Blue]

Originally Posted by 4thGenSSGuy

Valid question. Yes. Removing the suitcase muffler will hurt you on the aerodynamics. But to see the hurt truly mess with you-you probably need to be well past 100mph.

Thank you.

[Chrome383Z]

What’s interesting is that the upgraded GM performance exhaust (non-npp) is the same as aftermarket I believe. No suitcase. So GM isn’t too worried about it.

[4thGenSSGuy]

it's a Camaro -- a poor man's Corvette.

If you want the aero then buy a Lamborghini or Viper.

[CW3SF]

I didn’t notice any drag from the suitcase being replaced. But I went ahead and fabbed a sheet metal cover for that space. Nothing fancy but functional. Sorry but I don’t have any pics and I just had back surgery so I can’t crawl under the car.

[Z OH 6]

Originally Posted by Vigilante375

It is feasible that it could cause an "parachute" situation. Logically that is where pressie builds as the car gets pushed down, right?

If you look under race cars, let's say NASCAR, you don't see an opening like you would on the ZL1 without the suitcase exhaust. Yes those are race cars and not street cars but the law of physics doesn't care.

I don't know how many ZL1s without the stock suitcase actually races the road course regularly and at sustained speeds of over 100 mph.

I don't think anyone will experiment on how much drag this can make with and without the stock suitcase. But in theory, it will cause an issue but how much is beyond my caring since I'm never getting rid of the stock suitcase.

Not debating theory, just stating I've seen no factual data, just speculation. I find it very hard to believe the rear valence acts like a parachute. That's like saying my standard ZL1 wing provides as much downforce as the 1LE wing. What I do know is that there thousands of ZL1 owners that race their cars at tracks well above 100mph with aftermarket exhausts and don't complain about any increased drag or parachute effect. In theory, should there be some effect? Possibly so. Is it so minimal that its likely unnoticeable? Possibly so. I'd just like to see some data to see how much affect it really has.

[Z OH 6]

Originally Posted by Chrome383Z

What’s interesting is that the upgraded GM performance exhaust (non-npp) is the same as aftermarket I believe. No suitcase. So GM isn’t too worried about it.

Imagine that.

[4thGenSSGuy]

Camaro's empty rear box (if suitcase muffler is gone) will produce the same effect as a truck. Truck beds produce horrendous aero. Some say adding a topper or camper shell to a truck will produce an extra 5mpg at the pump.

Massive engineering error by GM in my opinion.

[Z OH 6]

Originally Posted by 4thGenSSGuy

Camaro's empty rear box (if suitcase muffler is gone) will produce the same effect as a truck. Truck beds produce horrendous aero. Some say adding a topper or camper shell to a truck will produce an extra 5mpg at the pump.

Massive engineering error by GM in my opinion.

I have a truck and I have a cover for my truck bed, I have tested my mpg with and without and can verify that it does increase mpg by .5mpg, that's pretty small, but I suppose you can say it is something. There's a lot more drag on a truck tailgate than under the Camaro rear valence. I think the argument for keeping the stock suitcase is a convenient way of justifying not swapping the stock exhaust due to cost. I admit, I use to be in the camp that cat back exhausts were a waste of money, and they are for performance but the sound and look is vastly improved over the stock suitcase.

[Vigilante375]

Originally Posted by Z OH 6

I have a truck and I have a cover for my truck bed, I have tested my mpg with and without and can verify that it does increase mpg by .5mpg, that's pretty small, but I suppose you can say it is something. There's a lot more drag on a truck tailgate than under the Camaro rear valence. I think the argument for keeping the stock suitcase is a convenient way of justifying not swapping the stock exhaust due to cost. I admit, I use to be in the camp that cat back exhausts were a waste of money, and they are for performance but the sound and look is vastly improved over the stock suitcase.

I'll counter with that there is more drag under a vehicle than in the bed of a truck. The bed has nothing above it while the underside of the vehicle has the ground.

The air flow will go into the bed in a circular pattern then will "bounce" out.

The air flow under the vehicle will kinda do the same but meets resistance with the ground and the vehicle.

Have you ever seen a vehicle driving down the road with a damaged rear valence? It looks like there is someone under it, poking it.

[Z OH 6]

Originally Posted by Vigilante375

I'll counter with that there is more drag under a vehicle than in the bed of a truck. The bed has nothing above it while the underside of the vehicle has the ground.

The air flow will go into the bed in a circular pattern then will "bounce" out.

The air flow under the vehicle will kinda do the same but meets resistance with the ground and the vehicle.

Have you ever seen a vehicle driving down the road with a damaged rear valence? It looks like there is someone under it, poking it.

Got data to support that? Everything I've found shows that the majority of underbody drag comes from the tires and wheel wells. As for the tailgate, studies show that it actually has very little drag because the air in the bed is trapped and can't go anywhere so the air over the top of the vehicles just passes right over. I have found little to show there's major drag under the vehicle other than tires and wheel wells, although there are improvements to be had in aerodynamics when a diffuser is added but thats after the suitcase muffler. Like I said, just looking for data, not speculation or theory.

[Chrome383Z]

If that flimsy plastic bumper cover was capturing any amount of air at 140mph it would rip that f*cker off.

[Z OH 6]

Originally Posted by Chrome383Z

If that flimsy plastic bumper cover was capturing any amount of air at 140mph it would rip that f*cker off.

That's my thinking too. I've yet to see it happen. Of course as I say that, someone will tell us about their sisters brothers cousin that had it happen. If it was an issue we certainly would have known about it by now.