LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently August 19, 2017, 2:36 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 99 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7
Author Message
PostPosted: April 30, 2016, 2:15 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7327
Location: Massachusetts
Quote:
It is not reversable. If it were reversed, I doubt it would do anything.


MV8, I just can't figure it out. How does the exhaust flow thru this? what's confusing me is you say it wouldn't work backwards, but it also sounds like the inner tube goes straight thru....

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
Reply with quote  
PostPosted: April 30, 2016, 2:52 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 5556
Cory,
all it would take to hold it in is one screw through the pipe, preferably into one of the bells.


Marcus,
If it were reversed, it would not be as effective. The outer chamber would have no outlet.
The center pipe has two slots covered with divergent ducts, asymmetrical to the center pipe.
Flow bounces off the closed end cap to flow over the same ducts which form another divergent duct to reach the slotted end cap.

I'm going to make a back pressure tester to compare noise to back pressure. I will be able to test while driving also.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: May 8, 2016, 1:42 pm 
Offline

Joined: April 1, 2010, 10:26 am
Posts: 316
I took the car out for it first long drive today, the exhaust is the quietest it has ever been, you can actually drive it, your not constantly in noise control mode. I added a SuperTrapp end cap, and a Vortex cone just before the muffler

Graham


Attachments:
IMG_20160130_114633974 (1).jpg
IMG_20160130_114633974 (1).jpg [ 1.8 MiB | Viewed 657 times ]
Top
 Profile  
Reply with quote  
PostPosted: July 26, 2016, 9:48 am 
Offline

Joined: June 18, 2016, 12:39 am
Posts: 121
For big HP with super quiet exhaust, it's difficult to beat Cadillac CTS-V mufflers. I've heard one of those 556-horse supercharhed 6.2s uncorked, no way any other street engine is any louder. But the main reason they didn't make the power of the 'vette version was the cam, not the muffs. The ZL1 Camaro used the CTS-V cam, but 'vette mufflers, and only made 580 HP, so a 14 HP loss is what, 3% at worst?


Top
 Profile  
Reply with quote  
PostPosted: July 26, 2016, 10:25 am 
Offline
User avatar

Joined: January 31, 2012, 12:49 pm
Posts: 1397
Location: Louisville KY
Dave1976 wrote:
Fso a 14 HP loss is what, 3% at worst?


Betting that HP loss graph isn't linear. So under 300 hp, probably less than 3%?

EDIT -- looking at the prices for this stuff. OWWWWWW!!!!!

_________________
***************
Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.
Girlfriend thinks I'm nuts for building this....


Top
 Profile  
Reply with quote  
PostPosted: July 26, 2016, 11:40 am 
Offline
Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
Posts: 5675
Location: SoCal
FastG wrote:
I took the car out for it first long drive today, the exhaust is the quietest it has ever been, you can actually drive it, your not constantly in noise control mode. I added a SuperTrapp end cap, and a Vortex cone just before the muffler
Graham

I had such a negative experience with a SuperTrapp setup that I can't bring myself to ever use one again. I remember my thought at the time, "they've created a product that has the amazing ability to both restrict power and be loud at the same time."

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
Reply with quote  
PostPosted: July 26, 2016, 9:54 pm 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 447
Location: White Rock, BC, Canada
FastG wrote:
I took the car out for it first long drive today, the exhaust is the quietest it has ever been, you can actually drive it, your not constantly in noise control mode. I added a SuperTrapp end cap, and a Vortex cone just before the muffler

Graham



Glad to know of another success. Did you try it with only the cones?
I'm still waiting to drive my car to test out my giant mufflers.

Quote:
I've heard one of those 556-horse supercharhed 6.2s uncorked, no way any other street engine is any louder.


Rotary for sure. I've done a dyno day where there were several LS cars, some with open exhaust. Loud for sure but when they ran the one big HP turbo RX7 everyone able to fled the building covering their ears.

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
PostPosted: June 6, 2017, 1:11 am 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 447
Location: White Rock, BC, Canada
Just got home from doing some sound testing with my car in its new, quieter form. Got 2 flybys of 90dB, and one (erroneous?) of 98dB. I'm surprised by how loud it still is when WOT. I think exhaust length is the biggest factor now. I did build a pair of cone inserts with a 1 5/8" hole which I will run at autox, but did not test on my car. I did test them on a friends LSx camaro though. Saw a 8dB reduction and I would say we were 5-10ft closer this time. I was pretty impressed by how much of a difference the cones make even just stuffed into the tail pipe. Even at idle it was much quieter. Granted, the 1 5/8" hole was not enough to maximize his power, but he doesn't need 500hp to do autoX.

I think I am safe once I stuff the inserts in my car. If not I will aim the tips upwards away from the sound meter. I intend for my my S/C to get a little louder at some point too so may need to build a second cone set. Oh, and one plus from the giant mufflers on my car is that it sounds much better. Honestly the best sounding 90° V6 I've ever heard. Still nowhere near as sexy as the LSx though......

Thanks again for the help. I will post after I try autoX. They can still shut me down even if I am below dB if it "seems" too loud. Basically if they hear sound reflecting off the trailers, and clouds they get concerned. Nothing against them, they are doing what it takes to keep the last autoX pad in the area.

Cheers.

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
PostPosted: July 24, 2017, 10:24 pm 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 447
Location: White Rock, BC, Canada
Update: I've done my first event in the car and am totally OK for sound. To the point that even when my right exhaust tip/insert fell off*, the sound levels were fine. It's quiet enough that no one even considered to check my levels. I do have a backfire on decell I should seal up, but no one brought it up.

Thanks again for the help. I'll probably just pull the inserts out and loan/give them to my friend with the loud Camaro to try.

Cheers.


* fell off is not really the right description: Got hammered off from repeated cone-impacts is probably more accurate :mrgreen:

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 99 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY