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MDesigns Race Spec Prototype - w/Video
- Thread starter JimiJak
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panther427
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I like it.
Nice job Jack!... good info too... I like the new exhaust note! :thumb:
I've been thinking more about exhaust lately due to the cutout thing. I have been impressed with one new idea by Spartn.... here's my thinking which Jack, Spartn, and I have discussed together.... I believe the ideas are sound (no pun intended, LOL)...
The catbacks available for SHO/MKS/transverse 3.5 EB.... (Except for the new one that Spartn has just gotten completed and Jack has installed) make what I think is at least potentially an error by staying dual and OEM size. I am a fan of dual exhausts, but you can't ignore the math in trying to increase flow after you deal with cats/mufflers/resonators/etc ..which are obvious. see below. Also note the GTR uses a similar design to improve exhaust note without raspiness or drone. I think we often make the mistake of trying to make our V6 sound like a V8... instead of a high performance V6 engine.
The numbers for cross-sectional are usually not thought of with an allowance for pipe wall thickness. All pipe is sold based on it's outside diameter, which is irrelevent to it's flow characteristics. To obtain the correct cross-sectional area of the inside of the pipe, you need to subtract the pipe thickness first. So check it out... using a single 3" pipe is actually bigger in cross section.
Some comparisons of pipe cross sectional area:
OD/ID(")...............Inside Area(sq. in.)
2.5/2.375....................4.430
3.0/2.875....................6.492
3.5/3.375....................8.946
So in fact, a single 3.5" pipe has a larger inside cross sectional area than two 2.5" pipes.
Something else to consider is the inside surface area, as measured along the inside walls, especially for the cooling effects on gas flow. The more wall area, the larger to friction with air trying to move through... This is even more dramatic, especially when the contraction of gas (due to cooling) slows it's movement simply because it looses volume.
Another comparison:
OD/ID...................Inside Surface
2.5/2.375..................7.461
3.0/2.875..................9.032
3.5/3.375.................10.601
As you can see, two 2.5" pipes would have approximately 40% more inside surface area than a single 3.5" pipe. The frictional losses from this extra area would likely be minimal, because the gases along the wall flow very slowly(relative to the gases nearer the center).... but they do move slower due to friction resulting in an increased back-pressure. More important, IMHO, is the cooling effect caused by gases in contact with the wall inside surface area. As these gases cool, they draw heat away from gases nearer to the center. As gas loses heat it loses volume and therefor velocity, the added inside surface of the dual pipes should cool the exhaust more than the single pipe and cause a corresponding loss in velocity of flow of engine exhaust... Cooler weather (which we want for our turb'd engine performance) should actually amplify this effect.
The sound part is proven I think (Thanks Jack!)... dyno's/track times on the MKS/SHO/XSport are still on the way
Just my 2 cents... but I think it's thought provoking when the math is done.
I've been thinking more about exhaust lately due to the cutout thing. I have been impressed with one new idea by Spartn.... here's my thinking which Jack, Spartn, and I have discussed together.... I believe the ideas are sound (no pun intended, LOL)...
The catbacks available for SHO/MKS/transverse 3.5 EB.... (Except for the new one that Spartn has just gotten completed and Jack has installed) make what I think is at least potentially an error by staying dual and OEM size. I am a fan of dual exhausts, but you can't ignore the math in trying to increase flow after you deal with cats/mufflers/resonators/etc ..which are obvious. see below. Also note the GTR uses a similar design to improve exhaust note without raspiness or drone. I think we often make the mistake of trying to make our V6 sound like a V8... instead of a high performance V6 engine.
The numbers for cross-sectional are usually not thought of with an allowance for pipe wall thickness. All pipe is sold based on it's outside diameter, which is irrelevent to it's flow characteristics. To obtain the correct cross-sectional area of the inside of the pipe, you need to subtract the pipe thickness first. So check it out... using a single 3" pipe is actually bigger in cross section.
Some comparisons of pipe cross sectional area:
OD/ID(")...............Inside Area(sq. in.)
2.5/2.375....................4.430
3.0/2.875....................6.492
3.5/3.375....................8.946
So in fact, a single 3.5" pipe has a larger inside cross sectional area than two 2.5" pipes.
Something else to consider is the inside surface area, as measured along the inside walls, especially for the cooling effects on gas flow. The more wall area, the larger to friction with air trying to move through... This is even more dramatic, especially when the contraction of gas (due to cooling) slows it's movement simply because it looses volume.
Another comparison:
OD/ID...................Inside Surface
2.5/2.375..................7.461
3.0/2.875..................9.032
3.5/3.375.................10.601
As you can see, two 2.5" pipes would have approximately 40% more inside surface area than a single 3.5" pipe. The frictional losses from this extra area would likely be minimal, because the gases along the wall flow very slowly(relative to the gases nearer the center).... but they do move slower due to friction resulting in an increased back-pressure. More important, IMHO, is the cooling effect caused by gases in contact with the wall inside surface area. As these gases cool, they draw heat away from gases nearer to the center. As gas loses heat it loses volume and therefor velocity, the added inside surface of the dual pipes should cool the exhaust more than the single pipe and cause a corresponding loss in velocity of flow of engine exhaust... Cooler weather (which we want for our turb'd engine performance) should actually amplify this effect.
The sound part is proven I think (Thanks Jack!)... dyno's/track times on the MKS/SHO/XSport are still on the way
Just my 2 cents... but I think it's thought provoking when the math is done.
panther427
New member
I like this set up. I want to hear the corsa in person. But this has sound but still mellow.
As Jack described there might be minor tweaks to the design and then I will have all details finalized, I am looking into changes to get more sound out of the catback without introducing rasp.
If everything goes according to plan I will be doing a baseline dyno with only mods being an intake system and then a pull with the exhaust and intake to get some real numbers out there.
If everything goes according to plan I will be doing a baseline dyno with only mods being an intake system and then a pull with the exhaust and intake to get some real numbers out there.
panther427
New member
I may go get this done but with a y right after the down pipe. Then the question would be cut out before or after the resonator.
Any thoughts of using the venturi effect in an exhaust system
Any thoughts of using the venturi effect in an exhaust system
panther427 said:I may go get this done but with a y right after the down pipe. Then the question would be cut out before or after the resonator.
Any thoughts of using the venturi effect in an exhaust system
I plan to hopefully offer the same exhaust kit though with a built in boost activated cut out. Personally I would like the exhaust cutout to be placed after the resonator which shouldn't hurt performance due to the free-flowing straight through design of the resonator. It should help reduce just a tad bit of rasp, somewhat of a resonated exhaust cut out.
panther427
New member
Well it's all talk at the moment. I can't decide what I want to spend my money on lol. But seriously good job on thinking outside the box with this. Really like the current sound. Deep and mellow. Reminds me and bit of GM 3.8 exhaust note. But I'm hoping for some Turbo whistle. That's the noise I want to hear.
You'll be happy to hear MDesigns is very open to all of our ideas.
From what I've heard from Spartn he is taking all of your comments under advisement and giving us all what we want. A sleeker, simpler design with a little more volume and a built in cut-out option. The system I have is perfect for the daily driver, or "sleeper" build that's looking to keep DBs down with no rasp and no drone.
It looks like this wasn't the final prototype after all.
@Spartn27, we look forward to the updates and improved design.
From what I've heard from Spartn he is taking all of your comments under advisement and giving us all what we want. A sleeker, simpler design with a little more volume and a built in cut-out option. The system I have is perfect for the daily driver, or "sleeper" build that's looking to keep DBs down with no rasp and no drone.
It looks like this wasn't the final prototype after all.
@Spartn27, we look forward to the updates and improved design.
JimiJak said:You'll be happy to hear MDesigns is very open to all of our ideas.
From what I've heard from Spartn he is taking all of your comments under advisement and giving us all what we want. A sleeker, simpler design with a little more volume and a built in cut-out option. The system I have is perfect for the daily driver, or "sleeper" build that's looking to keep DBs down with no rasp and no drone.
It looks like this wasn't the final prototype after all.
@Spartn27, we look forward to the updates and improved design.
Thanks for all the help Jack!
SHOdded said:It's nice to see homegrown businesses come to fruition, and I wish MDesigns the very best of luck in their launch and further endeavors.
Thank you! Just trying to give the consumers what they need at a good price, as I know how it feels to be a consumer myself!
JimiJak said:You'll be happy to hear MDesigns is very open to all of our ideas.
From what I've heard from Spartn he is taking all of your comments under advisement and giving us all what we want. A sleeker, simpler design with a little more volume and a built in cut-out option. The system I have is perfect for the daily driver, or "sleeper" build that's looking to keep DBs down with no rasp and no drone.
It looks like this wasn't the final prototype after all.
@Spartn27, we look forward to the updates and improved design.
I would be moreinterested as is. I do not like a lot of noise. Especially the drone sound of a V6 trynna sound like a V8. What you have is great. So if he does continue to make changes, please have an option to keep the "silent sleeper" alive and well. Dont wanna be heard or seen. Just tail lights. (get it) lol.
Dxlnt1 said:JimiJak said:You'll be happy to hear MDesigns is very open to all of our ideas.
From what I've heard from Spartn he is taking all of your comments under advisement and giving us all what we want. A sleeker, simpler design with a little more volume and a built in cut-out option. The system I have is perfect for the daily driver, or "sleeper" build that's looking to keep DBs down with no rasp and no drone.
It looks like this wasn't the final prototype after all.
@Spartn27, we look forward to the updates and improved design.
I would be moreinterested as is. I do not like a lot of noise. Especially the drone sound of a V6 trynna sound like a V8. What you have is great. So if he does continue to make changes, please have an option to keep the "silent sleeper" alive and well. Dont wanna be heard or seen. Just tail lights. (get it) lol.
Depending on how the new design sounds I'll know if it will be necessary to have both options, Im planning on it opening the exhaust just a tad more without adding rasp. I am all for the silent sleeper look as I do own a MKS which people tend to think is an "old mans car", therefore precautions are being taken as with the prior design to keep drone/rasp to a bare minimum, if any at all.
As far as "old man car" little do they know what's under the hood!
panther427
New member
My thoughts aren't after trying to majdtgt louder. Only thoughts on making it possibly cheaper and easier to make and install. Though in curious to the sound change with the resonator in the 3 inch section. If any
You should dyno each exhaust you do make. See if there is a change in power between design.
You should dyno each exhaust you do make. See if there is a change in power between design.
panther427 said:My thoughts aren't after trying to majdtgt louder. Only thoughts on making it possibly cheaper and easier to make and install. Though in curious to the sound change with the resonator in the 3 inch section. If any
You should dyno each exhaust you do make. See if there is a change in power between design.
Those revisions are currently being looked at and parts ordered for them, also contacted LMS to figure out dyno costs and will be heading down after I get some maintenance done on the car. Would like to have the PTU BG serviced and flushed along with my brake kit installed before jumping on the dyno or doing any track testing.
Now it's just a waiting game with the UPS man!
panther427
New member
I understand it's always about time and money.. I know I really like what you have come up with and wanna help.
Thanks for your hard work
Thanks for your hard work
Outstanding work gentlemen!
:clap2:
I haven't been fond of the sound or price of any of the current offerings.
It's about time somebody designed a system to enhance the tt V-6 sound, I don't want my force fed Big Girl to sound like a V-8. If I wanted the characteristics of a V-8 I'd be driving a Mustang.
I look forward to some drive by vids at full tilt.
:thankyou:
:clap2:
I haven't been fond of the sound or price of any of the current offerings.
It's about time somebody designed a system to enhance the tt V-6 sound, I don't want my force fed Big Girl to sound like a V-8. If I wanted the characteristics of a V-8 I'd be driving a Mustang.
I look forward to some drive by vids at full tilt.
:thankyou:
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