Aluminum plate that covers the mid exhaust section
08-23-2015, 09:21 PM
#1
Melting Slicks
Thread Starter
Aluminum plate that covers the mid exhaust section
Is the mid plate made out of aluminum there for strength to tie in the frame rails?. Being that I will only 1/4 mile my car with street tires, I am thinking about unbolting it to allow exhaust heat to escape. Am I missing something as it covers the exhaust and should never need the extra stiffening that it provides.
08-23-2015, 09:37 PM
#2
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Is the mid plate made out of aluminum there for strength to tie in the frame rails?. Being that I will only 1/4 mile my car with street tires, I am thinking about unbolting it to allow exhaust heat to escape. Am I missing something as it covers the exhaust and should never need the extra stiffening that it provides.
Now driving the car 1/4 mile not going & getting on it in the car like for a long time you will be fine. They is not that much heat coming up into the car from that.
08-23-2015, 11:41 PM
#3
Drifting
Do not underestimate the contribution to structural stiffness that plate makes. If there was no significant load going through it, why so many heavy fasteners...? It's called a shear panel and takes its load in tension/compression, but greatly enhances the car's global torsion/bending stiffness as well as NVH characteristics. No, the car won't break in half if you leave it off (at least not right away), but you're attempting to alleviate a non-problem by introducing a real one. And yes, I do this for a living. 
Last edited by xp800; 08-23-2015 at 11:45 PM.
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08-24-2015, 08:22 AM
#4
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Do not underestimate the contribution to structural stiffness that plate makes. If there was no significant load going through it, why so many heavy fasteners...? It's called a shear panel and takes its load in tension/compression, but greatly enhances the car's global torsion/bending stiffness as well as NVH characteristics. No, the car won't break in half if you leave it off (at least not right away), but you're attempting to alleviate a non-problem by introducing a real one. And yes, I do this for a living.
08-24-2015, 09:10 AM
#5
Melting Slicks
Thread Starter
Do not underestimate the contribution to structural stiffness that plate makes. If there was no significant load going through it, why so many heavy fasteners...? It's called a shear panel and takes its load in tension/compression, but greatly enhances the car's global torsion/bending stiffness as well as NVH characteristics. No, the car won't break in half if you leave it off (at least not right away), but you're attempting to alleviate a non-problem by introducing a real one. And yes, I do this for a living.
08-24-2015, 10:02 AM
#6
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my c7 has a heat sheet of something on the under side of the tunnel area. The c7 is better than the c5 for sure on small stuff.
08-25-2015, 11:16 AM
#7
Melting Slicks
No way would I take that plate off, your car will see significant torque/twisting during a drag strip launch.
You won't shed much more heat anyway by removing it. You would be better served to buy one of these for use in the pits at the track:
http://www.homedepot.com/p/Powr-Flit...D500/203004575
You won't shed much more heat anyway by removing it. You would be better served to buy one of these for use in the pits at the track:
http://www.homedepot.com/p/Powr-Flit...D500/203004575
08-25-2015, 11:48 AM
#8
Melting Slicks
Thread Starter
No way would I take that plate off, your car will see significant torque/twisting during a drag strip launch.
You won't shed much more heat anyway by removing it. You would be better served to buy one of these for use in the pits at the track:
http://www.homedepot.com/p/Powr-Flit...D500/203004575
You won't shed much more heat anyway by removing it. You would be better served to buy one of these for use in the pits at the track:
http://www.homedepot.com/p/Powr-Flit...D500/203004575
I agree on slicks with higher horse/torgue combos will tax the chassis stiffness
08-25-2015, 12:02 PM
#9
Drifting
Hi 10MM, I am only talking about 1 or two passes down the 1/4 mile with factory tires and a base non z51 car. The car is used 99% for street use only. No drifting or road course tracks for me. Regarding less heat, not for the track, just better exhaust/tunnel cooling for everyday driving.
I agree on slicks with higher horse/torgue combos will tax the chassis stiffness
I agree on slicks with higher horse/torgue combos will tax the chassis stiffness
08-25-2015, 12:26 PM
#10
Melting Slicks
Thread Starter
Again, I strongly recommend against operating the car with the tunnel brace removed. It's there for numerous reasons, and a very good ones at that. Where do you get the notion that the heat in the tunnel is problematic for any operational mode you would have on the street? And why would you introduce vehicle-level structure compromises for "reducing" a heat issue you are speculating exists? It just makes no sense.
08-25-2015, 01:06 PM
#11
Melting Slicks
Hi 10MM, I am only talking about 1 or two passes down the 1/4 mile with factory tires and a base non z51 car. The car is used 99% for street use only. No drifting or road course tracks for me. Regarding less heat, not for the track, just better exhaust/tunnel cooling for everyday driving.
I agree on slicks with higher horse/torgue combos will tax the chassis stiffness
I agree on slicks with higher horse/torgue combos will tax the chassis stiffness
Also your car will see the torque/twisting load the entire way down the track, take it from someone who has made hundreds of passes in dozes of cars I can tell you for sure you do NOT want to twist your car like that.
I have seen people on street tires twist their car so bad the doors don't close properly, and they were slower than a stock C7.
If you have ever installed a tubular or modified transmission cross member and seen the drastic difference it can make in chassis flex you would agree that removing anything structural in that location is not a good idea.
It's your car, do what you want. I just wouldn't recommend it.
08-25-2015, 01:24 PM
#12
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The stock tires on these cars are very capable, I wouldn't under estimate them.
Also your car will see the torque/twisting load the entire way down the track, take it from someone who has made hundreds of passes in dozes of cars I can tell you for sure you do NOT want to twist your car like that.
I have seen people on street tires twist their car so bad the doors don't close properly, and they were slower than a stock C7.
If you have ever installed a tubular or modified transmission cross member and seen the drastic difference it can make in chassis flex you would agree that removing anything structural in that location is not a good idea.
It's your car, do what you want. I just wouldn't recommend it.
Also your car will see the torque/twisting load the entire way down the track, take it from someone who has made hundreds of passes in dozes of cars I can tell you for sure you do NOT want to twist your car like that.
I have seen people on street tires twist their car so bad the doors don't close properly, and they were slower than a stock C7.
If you have ever installed a tubular or modified transmission cross member and seen the drastic difference it can make in chassis flex you would agree that removing anything structural in that location is not a good idea.
It's your car, do what you want. I just wouldn't recommend it.
I wouldn't care if it was 1/4 thick on my car. That is what I put in my c5 blower car and you can tell a diff in that bolted under the car believe it are not.. Robert
08-26-2015, 03:23 AM
#13
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St. Jude Donor '14-'15
While others have covered the rigidity and structural issues here, I can perhaps help a bit with the assumption that there would be a tangible temp reduction.
I ran without this plate for a short period (for the sake of tunnel-temp testing leading up to EGT @ the AFM valves) during my initial valve testing.
There was no tangible benefit in temperature differential to removing the plate (none whatsoever), but the increased chassis flex was immediately noticeable.
I ran without this plate for a short period (for the sake of tunnel-temp testing leading up to EGT @ the AFM valves) during my initial valve testing.
There was no tangible benefit in temperature differential to removing the plate (none whatsoever), but the increased chassis flex was immediately noticeable.
08-26-2015, 08:25 AM
#14
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While others have covered the rigidity and structural issues here, I can perhaps help a bit with the assumption that there would be a tangible temp reduction.
I ran without this plate for a short period (for the sake of tunnel-temp testing leading up to EGT @ the AFM valves) during my initial valve testing.
There was no tangible benefit in temperature differential to removing the plate (none whatsoever), but the increased chassis flex was immediately noticeable.
I ran without this plate for a short period (for the sake of tunnel-temp testing leading up to EGT @ the AFM valves) during my initial valve testing.
There was no tangible benefit in temperature differential to removing the plate (none whatsoever), but the increased chassis flex was immediately noticeable.
Again here like I said above in my c5 I could tell a big diff from the stock one that came on the car & the one aftermarket that is 1/4 inch thick. If & when someone makes one a 1/4 thick I will buy it for sure. Robert
08-26-2015, 09:05 AM
#15
Burning Brakes
Drill a few holes in it............
08-26-2015, 01:16 PM
#16
Drifting
Just to clarify a few things on the structures side...dust off your Statics 101 books and get out a napkin for a free-body diagram if you need to.
The torque tube that couples the engine to the transaxle in the Corvette reacts ALL the torque generated by the motor to the differential; the body does not. This is the major benefit of this architecture. Typical front engine/rear wheel drive cars react powertrain torque with the body. So no matter how much torque the Vette motor makes, it won't "twist the car" on acceleration. There will still be the powertrain "inertial" roll torque from the rotational acceleration of the engine internals, but this relatively small and is reacted by the powertrain mounts as vertical forces (no fore-aft twist).
In fact, the powertrain is fully isolated from the body, so it does not add or diminish to global vehicle stiffness. And the loads into the body from the powertrain under acceleration are fundamentally from the tractive force at the rear tires' contact patches. These tractive forces are reacted by the suspension mounts to "push" the car forward, and the torque from halfshafts is reacted by the body mounts as a vertical force couple. This induces vertical bending in the powertrain (small, mostly contained in the torque tube) but does not "twist" the body.
The tunnel brace in the Corvette adds to global body stiffness as I mentioned before. It's a significant increase in both the bending and torsion moments of inertia. It forms a closed section with the tunnel helping both body torsion stiffness (like its own local torque tube) and vertical/lateral bending stiffness, increases local floorpan vertical stiffness by preventing the tunnel from 'breathing" (spreading open and closed), and improves side impact body integrity by distributing load to the non-struck side of the car.
The global vehicle stiffness is what we experience qualitatively as the feeling of "solidity" (or lack thereof) and handling precision (or lack thereof) from chassis/road inputs as well as engine vibration inputs. A stiff structure lets the suspension do what it needs to for better isolation and handling, and a stiff vehicle will tend to flex/vibrate less for improved NVH (and perceived solidity/quality). All the torque tube does is relieve the body from one of the largest force and vibration inputs.
All that said, leave the plate on. A thicker plate -may- help incrementally on a C7, but the tradeoff between added mass to added stiffness can go south faster than you might imagine. The previous generations of Corvettes were MUCH less stiff than the C7, and a it's quite believable that thicker tunnel brace produced a noticeable effect. But the C7 architecture is so much stiffer and the tunnel brace has been optimized in concert with this (by some smart folks...) to give the best thickness/mass for its intended effect.
/geek mode
The torque tube that couples the engine to the transaxle in the Corvette reacts ALL the torque generated by the motor to the differential; the body does not. This is the major benefit of this architecture. Typical front engine/rear wheel drive cars react powertrain torque with the body. So no matter how much torque the Vette motor makes, it won't "twist the car" on acceleration. There will still be the powertrain "inertial" roll torque from the rotational acceleration of the engine internals, but this relatively small and is reacted by the powertrain mounts as vertical forces (no fore-aft twist).
In fact, the powertrain is fully isolated from the body, so it does not add or diminish to global vehicle stiffness. And the loads into the body from the powertrain under acceleration are fundamentally from the tractive force at the rear tires' contact patches. These tractive forces are reacted by the suspension mounts to "push" the car forward, and the torque from halfshafts is reacted by the body mounts as a vertical force couple. This induces vertical bending in the powertrain (small, mostly contained in the torque tube) but does not "twist" the body.
The tunnel brace in the Corvette adds to global body stiffness as I mentioned before. It's a significant increase in both the bending and torsion moments of inertia. It forms a closed section with the tunnel helping both body torsion stiffness (like its own local torque tube) and vertical/lateral bending stiffness, increases local floorpan vertical stiffness by preventing the tunnel from 'breathing" (spreading open and closed), and improves side impact body integrity by distributing load to the non-struck side of the car.
The global vehicle stiffness is what we experience qualitatively as the feeling of "solidity" (or lack thereof) and handling precision (or lack thereof) from chassis/road inputs as well as engine vibration inputs. A stiff structure lets the suspension do what it needs to for better isolation and handling, and a stiff vehicle will tend to flex/vibrate less for improved NVH (and perceived solidity/quality). All the torque tube does is relieve the body from one of the largest force and vibration inputs.
All that said, leave the plate on. A thicker plate -may- help incrementally on a C7, but the tradeoff between added mass to added stiffness can go south faster than you might imagine. The previous generations of Corvettes were MUCH less stiff than the C7, and a it's quite believable that thicker tunnel brace produced a noticeable effect. But the C7 architecture is so much stiffer and the tunnel brace has been optimized in concert with this (by some smart folks...) to give the best thickness/mass for its intended effect.
/geek mode
Last edited by xp800; 08-26-2015 at 01:55 PM.
08-26-2015, 01:40 PM
#17
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Just to clarify a few things on the structures side...dust off your Statics 101 books and get out a napkin for a free-body diagram if you need to.
The torque tube that couples the engine to the transaxle in the Corvette reacts ALL the torque generated by the motor to the differential; the body does not. This is the major benefit of this architecture. Typical front engine/rear wheel drive cars react powertrain torque with the body. So no matter how much torque the Vette motor makes, it won't "twist the car" on acceleration. There will still be the powertrain "inertial" roll torque from the rotational acceleration of the engine internals, but this relatively small and is reacted by the powertrain mounts as vertical forces (no fore-aft twist).
In fact, the powertrain is fully isolated from the body, so it does not add or diminish to global vehicle stiffness. And the loads into the body from the powertrain under acceleration are fundamentally from the tractive force at the rear tires' contact patches. These tractive forces are reacted by the suspension mounts to "push" the car forward, and the torque from halfshafts is reacted by the body mounts as a vertical force couple. This induces vertical bending in the powertrain (small, mostly contained in the torque tube) but does not "twist" the body.
The tunnel brace in the Corvette adds to global body stiffness as I mentioned before. It's a significant increase in both the bending and torsion moments of inertia. It forms a closed section with the tunnel helping both body torsion stiffness (like its own local torque tube) and vertical/lateral bending stiffness, increases local floorpan vertical stiffness by preventing the tunnel from 'breathing" (spreading open and closed), and improves side impact body integrity by distributing load to the non-struck side of the car.
All that said, leave the plate on. A thicker plate -may- help incrementally on a C7, but the tradeoff between added mass to added stiffness can go south faster than you might imagine. The previous generations of Corvettes were MUCH less stiff than the C7, and a it's quite believable that thicker tunnel brace produced a noticeable effect. But the C7 architecture is so much stiffer and the tunnel brace has been optimized in concert with this (by some smart folks...) to give the best thickness/mass for its intended effect.
/geek mode
The torque tube that couples the engine to the transaxle in the Corvette reacts ALL the torque generated by the motor to the differential; the body does not. This is the major benefit of this architecture. Typical front engine/rear wheel drive cars react powertrain torque with the body. So no matter how much torque the Vette motor makes, it won't "twist the car" on acceleration. There will still be the powertrain "inertial" roll torque from the rotational acceleration of the engine internals, but this relatively small and is reacted by the powertrain mounts as vertical forces (no fore-aft twist).
In fact, the powertrain is fully isolated from the body, so it does not add or diminish to global vehicle stiffness. And the loads into the body from the powertrain under acceleration are fundamentally from the tractive force at the rear tires' contact patches. These tractive forces are reacted by the suspension mounts to "push" the car forward, and the torque from halfshafts is reacted by the body mounts as a vertical force couple. This induces vertical bending in the powertrain (small, mostly contained in the torque tube) but does not "twist" the body.
The tunnel brace in the Corvette adds to global body stiffness as I mentioned before. It's a significant increase in both the bending and torsion moments of inertia. It forms a closed section with the tunnel helping both body torsion stiffness (like its own local torque tube) and vertical/lateral bending stiffness, increases local floorpan vertical stiffness by preventing the tunnel from 'breathing" (spreading open and closed), and improves side impact body integrity by distributing load to the non-struck side of the car.
All that said, leave the plate on. A thicker plate -may- help incrementally on a C7, but the tradeoff between added mass to added stiffness can go south faster than you might imagine. The previous generations of Corvettes were MUCH less stiff than the C7, and a it's quite believable that thicker tunnel brace produced a noticeable effect. But the C7 architecture is so much stiffer and the tunnel brace has been optimized in concert with this (by some smart folks...) to give the best thickness/mass for its intended effect.
/geek mode
That has been proven in the past on every car that has been made.
08-26-2015, 02:32 PM
#18
Safety Car
I have to laugh a little bit about this thread. The OP comes in, apparently asking for advice. Every bit of advice, much of it from people with real expertise, says don't do it, but the OP continues to make excuses why it's OK.
Sounds like the OP didn't really want advice, he wanted validation.
It's a bad idea. Probably even worse on the street than on the strip, given the way potholes, frost heaves, driveway aprons and the like will torque your chassis, weakening it a little bit every time.
A few quarter mile runs, with cool down time in between, will not hurt you car (at least not by overheating the exhaust). Neither will street driving, unless maybe your normal commute is in downtown Riyad in the summer. Removing a key part of the structure of your car very possibly will.
But you appear determined to do it anyway, so do what you think best.
Sounds like the OP didn't really want advice, he wanted validation.
It's a bad idea. Probably even worse on the street than on the strip, given the way potholes, frost heaves, driveway aprons and the like will torque your chassis, weakening it a little bit every time.
A few quarter mile runs, with cool down time in between, will not hurt you car (at least not by overheating the exhaust). Neither will street driving, unless maybe your normal commute is in downtown Riyad in the summer. Removing a key part of the structure of your car very possibly will.
But you appear determined to do it anyway, so do what you think best.
Last edited by meyerweb; 08-26-2015 at 02:44 PM.
08-26-2015, 09:25 PM
#19
Racer
Maybe we should start a "Darwin Award" section in this forum ?
