The Lotus Cars Community banner
21 - 40 of 75 Posts

·
Registered
Joined
·
1,315 Posts
Is there a dB rating for the stock exhaust to compare against the other values. I would like to lose the weight for a stage 1. Stage 2 could be into the hearing damage levels though.(and I like my neighbours):)
 

·
Premium Member
Joined
·
29,081 Posts
Standard exhaust is rated at 93dB.

Both Stock and Stage 1 are 25 pounds.

Stage 2 is about 15 pounds and 105dB and for competition use only (not for street).
 

·
Registered
Joined
·
4,634 Posts
After quite a bit of searching, I came up with this as a likely answer to the question of what distance from the exhaust tip these sound pressure levels (noise levels) are measured:

....The legislation require the use of Society of Automotive Engineers test procedure J1169, which employs the A-weighted dB scale to measure exhaust sound--based on 95 decibels at 20 inches. ...

I don't know why 20 inches, but this seems to be the standard for auto exhausts. I would have guessed a distance of 1 meter, as this is generally the distance from which reference noise measurements are taken for equipment (pumps, fans, motors etc.).
 

·
Premium Member
Joined
·
29,081 Posts
Anyone have the conversion for translating that to 75 feet away? I *know* how loud 93dB is at 75 feet, but I don't know how loud a 93dB exhaust at 20" is.
 

·
Registered
Joined
·
6,301 Posts
Randy Chase said:
Standard exhaust is rated at 93dB.

Both Stock and Stage 1 are 25 pounds.

Stage 2 is about 15 pounds and 105dB and for competition use only (not for street).

surprised that stage 1 is not lighter than stock. I thought they had said any performance gain from stage 1 was related only to difference in weight as the stock exhaust was already optimized.Would that mean there is no performance gain from stage 1, just a better sound????
 

·
Registered
Joined
·
1,744 Posts
Discussion Starter · #29 ·
Randy Chase said:
Standard exhaust is rated at 93dB.

Both Stock and Stage 1 are 25 pounds.

Stage 2 is about 15 pounds and 105dB and for competition use only (not for street).
My dealer said stage I is 24 lbs lighter than stock. I also heard nothing about comp use only?

Where did you hear this information? Are you sure? If so the dealers are spreading wrong information as more than one person here has reported similar specs.
 

·
Registered
Joined
·
3,927 Posts
The number I'd dug up was a 6db drop for every doubling of distance. So in the case of the Stage II at 105db, at 75 ft I'd guess it'll be a good 27 db down.

From what I'd heard early on stage I was better looking, nicer tips. 4db will be noticeable but fairly minor gain is sound level but no real preformance gain.
 

·
Registered
Joined
·
687 Posts
Randy Chase said:
Standard exhaust is rated at 93dB.

Both Stock and Stage 1 are 25 pounds.

Stage 2 is about 15 pounds and 105dB and for competition use only (not for street).
That means Stage 2 is about twice as loud as stock, so if you want a loudness demo, play a video of the stock exhaust at 2x the volume. :p
 

·
Registered
Joined
·
7,432 Posts
Anyone else interested in the Custom Interior Items? How custom are we talking here? Anyone figure out a IPod adapter Yet? I know someone was working on it.

Has anyone seen or know what the center console is or looks like that continues to be referred to on this thread?
 

·
Registered
Joined
·
4,634 Posts
Based on a dropoff rate of 6 dB/doubling of distance (which is a good assumption in the free field for a point source such as an exhaust) the decrease in noise level would be 33 dB, from 20 inches to 75 feet.

So an exhaust putting out 93 dBA at 20 inches would be equivalent to 60 dBA at 75 feet. One caveat: an exhaust in the real world is not in the "free field" (i.e., a space free of reflecting surfaces etc.), so in fact the noise level could be as much as 3 dB higher, potentially even a bit more because of other complicating factors. But that's a good estimate, anyway.
 

·
Premium Member
Joined
·
29,081 Posts
Derek said:
My dealer said stage I is 24 lbs lighter than stock. I also heard nothing about comp use only?

Where did you hear this information? Are you sure? If so the dealers are spreading wrong information as more than one person here has reported similar specs.
Heard from Lotus.

Am I Sure? I am never sure. But I believe Lotus more than dealers.
 

·
Registered
Joined
·
970 Posts
is the leather wrapped center console stock or an option????....I need that!....wow, didnt know all these options were available...I need clearless bra, HID, st II exhaust and now ceneter console..guess theres one advantage of getting car next yr..:)
 
21 - 40 of 75 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top