True Dual Catback Aerodynamic Issue
03-22-2005, 10:01 AM
#22
My fiberglass speaker box project is ongoing but as soon as it is done, this is my next project. I should have built them in tandem seeing as how I had the resin all mixed up and keep needing to put on my glassing suit.
I built a basic mock up out of foam core and after adding some foam for shaping and rounding of edges, I should be able to turn it directly into a mold for a rear diffuser. Mounting will be on three pedestals with only a need for small holes to be drilled into the trunk floor.
All painted up to match my PPW when done, it should look stock to the onlooker.
Unless it is easy to churn them out like cheese wiz, I don't expect to be going into production or anything (it is hard enough to find the time to do the stuff I need to do), but I will write a "how to" if anyone wants to make their own.
Chris
I built a basic mock up out of foam core and after adding some foam for shaping and rounding of edges, I should be able to turn it directly into a mold for a rear diffuser. Mounting will be on three pedestals with only a need for small holes to be drilled into the trunk floor.
All painted up to match my PPW when done, it should look stock to the onlooker.
Unless it is easy to churn them out like cheese wiz, I don't expect to be going into production or anything (it is hard enough to find the time to do the stuff I need to do), but I will write a "how to" if anyone wants to make their own.
Chris
03-22-2005, 11:38 AM
#23
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It was a valid and construtctive point to bring up, but it's not practical for anyone to market anything that will "cure" this supposed problem.
The reason being: there are too many exhaust setups out there on the market, that mount differently, so how can you produce one cure all part for the car, if it won't fit everything? Heck, it could only really fit only one exhaust setup, so something like this would have to be a custom project all the way.[/QUOTE]
So true...
The reason being: there are too many exhaust setups out there on the market, that mount differently, so how can you produce one cure all part for the car, if it won't fit everything? Heck, it could only really fit only one exhaust setup, so something like this would have to be a custom project all the way.[/QUOTE]
So true...
03-22-2005, 12:26 PM
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Just a thought, so no flames please. What if the exhaust mfg co's were encouraged to design and produce a product that would work for their specific exhaust system? Wouldn't that solve the differing configuration issue?
03-23-2005, 05:58 PM
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Based on Tony's response....
Originally Posted by Chebosto
My main concern was when i swapped out my stock exhaust for the RSR, was that "whoa! there's now this huge void where my muffler used to be, and what's this? i think it was a diffuser to begin with" concern.
i've noticed from observing my own car during highway driving that yes, my back bumper does vibrate slightly. I didnt remove any mounting points for the rear bumper, so i suspect that it's due to the fact i have now nothing where there was something, and air is being trapped.
if you look at alot of the new body kit designs coming out for the Z, you'll notice several ducts,slots, and holes slightly below the support beam on the rear bumper. and i suspect this to aleviate the air being trapped. Now a generic aftermarket diffuser probably won't work for everyone. Hell, about 80% of the dual canister muffler designs out there will block optimum placement of any channel/diffuser you can use since you want to smooth the air immediatly following the rear axle, and the only clear exhaust choice is either with a custom HKS single exhaust, or the Greddy Evo2.
now, what some people have come up with is yes, ffill that void, under neath the heat shield with a block of something to force the air flow to go under the bumper flap- you may do with with your idea of a heat-treated foam. i was going to try to jsut cut out a piece of cardboard cut to fit, then lay fiberglass over it to make it rigid. either way should suffice, but i havent thought clearly enough on how to mount this. you'll need some sort of Xbrace underneath there so this doesnt come off..
the easiest way i think would to be cutting holes into the stock rear bumper, and that's probably what i'll do inconjunction with sometype of flat cover piece.
if you're worried about lift, then i suggest a wing of some type...
cuz you know, what better place to picnic, that ontop of your car trunk?
i've noticed from observing my own car during highway driving that yes, my back bumper does vibrate slightly. I didnt remove any mounting points for the rear bumper, so i suspect that it's due to the fact i have now nothing where there was something, and air is being trapped.
if you look at alot of the new body kit designs coming out for the Z, you'll notice several ducts,slots, and holes slightly below the support beam on the rear bumper. and i suspect this to aleviate the air being trapped. Now a generic aftermarket diffuser probably won't work for everyone. Hell, about 80% of the dual canister muffler designs out there will block optimum placement of any channel/diffuser you can use since you want to smooth the air immediatly following the rear axle, and the only clear exhaust choice is either with a custom HKS single exhaust, or the Greddy Evo2.
now, what some people have come up with is yes, ffill that void, under neath the heat shield with a block of something to force the air flow to go under the bumper flap- you may do with with your idea of a heat-treated foam. i was going to try to jsut cut out a piece of cardboard cut to fit, then lay fiberglass over it to make it rigid. either way should suffice, but i havent thought clearly enough on how to mount this. you'll need some sort of Xbrace underneath there so this doesnt come off..
the easiest way i think would to be cutting holes into the stock rear bumper, and that's probably what i'll do inconjunction with sometype of flat cover piece.
if you're worried about lift, then i suggest a wing of some type...
cuz you know, what better place to picnic, that ontop of your car trunk?I'm curious as to what speed you were going when you experienced vibration. I have had various bikes and 4-wheel vehicles and modified them significantly, and have never experienced any wind flow related problems.. I have my Z on order, and look forward to tuning the Z and am curious about the issues you are experiencing. Are you tearing it up? It appears that Tony would imply that the issues you are experiencing would only occur at high speeds. If its under 120mph, its no biggie anymore for me because a kid has cooled my right foot a bit.. Your insight is much appreciated in any event.
Ben
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