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Robert and I again flogged the Elise today. Some interesting notes.

As posted elsewhere, we just tweaked the alignment. Our new Hoosiers are not in yet, so it was decided to run on the street tires. For the first time in MANY days, we might also have rain.

The first two runs of the day were done by the Elise as a safety steward test of the course (something San Diego always does). The course was very wet with standing pools of water. The A048s have very little tread left.

The car in the wet was a hoot and very controllable. I did a 66 second run that stood for a while as top time of the day.

Robert and I ran in the afternoon in Super Stock against a number of Z-06 Corvettes. One nationally prepped and on 710s, the other a local fast guy on 710s. We again were on the A048s. The course was dry, on asphalt, temps around 75 degrees. Course was about 1.2 miles long and mostly in upper 2nd gear up to rev limiter.

Let me preface the results first. In San Diego, we have sound limits. And a sound meter. Strict rules. If you go above 93dB.... you can make a mechanical change to the car and your run is disqualified. Keep going over 93dB... and you will not be allowed to run anymore.

During the safety run in the wet, we hit 93dB. I thought that might have been high because it seems to happen more when it is wet out. So I was not too concerned.

I took my 4 runs first. On my first run, I was notified I was at 94dB. Holy crap. Now... it just so happens the person claiming I was over is also someone who works full time to make my life miserable :) so I don't know how loud the dB reading was really.

But in any case, if we went over 93 again, it was a very bad thing. So from them on... instead of staying on the cams for a distance about a 1000 yards long.... I shifted to 3rd and babied the throttle. This kept the sound down, but also added some time.

On Robert's last run, he opened it back up because they could no longer disqualify the car from suibsequent runs... since we were done. :) His last run though was a 92.7dB.

Now the really good thing. The car stuck. I was able to carry a lot of speed in the corners and get the car to even "drift" under control in a large sweeper turn before the finish. I was also able to flick the car through offsets. What it reminded me of... was the car I drove at the West Coast Lotus Meet autocross.

And I think it is mainly the alignment. If we had the Hoosiers, I think we could have been 2 seconds faster. If we did not have the sound violation problem, we could have gained a second back. Maybe even more.

Mark Duerst Z-06 59.765
Steve Schmidt Z-06 60.521
Randy Chase Elise 61.243
Robert Puertas Elise 62.019

So... getting closer. Next we try the alignment with Hoosiers and see what happens and if we need to make changes. Then a swaybar. Then shocks.

And yes sadly.. I think we will have to remove the quicksilver exhaust locally and run stock.
 

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That's a bummer. Your QS will get quieter after a few hundred more miles ( I think you only have about 300 miles on it?). But I don't know if that is enough to meet these sound limits.

QS can make a quieter exhaust. Any idea what the rpms were when you passed the sound meter? How far was the meter from the car? We'll have to discuss some of these details.
 

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One thing to consider Shinoo.. is that SCCA is considering or working on a proposal for a national sound limit, and they are using San Diego as a blueprint. So other people may end up having the same limitations.

The sound is taken with a db meter placed at 50 feet.

I was Wide Open Throttle... floored. Second gear. Around 7000rpms to 7500rpms.

If there was some way they could take it down a notch like 1-2dB at 50 feet. That would be good.
 

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Randy Chase said:
Now... it just so happens the person claiming I was over is also someone who works full time to make my life miserable :)
Hey, MW. Could be relatives of B and P?

Randy. Speak with MW. Have you ever seen Hitchcock's "Strangers on a train?" :D
 

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I'm amazed that you would have problems with noise limits. I can't imagine that an Elise with an upgraded exhaust is all that loud. What do the Prepared and Modified cars do? Even compared to a stock car with a straight pipe, the Prepared guys are normally orders of magnitude louder. Especially the ones that can blow down cones with their exhausts.
 

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The Elise seem to have some potential for add-on silencing tips. There appears to be enough room and if it extended back there is some potential to create a hanger using existing fasteners. I'm taking about a longer tip that would load into the present QS tip when desired.

There are also load-in inserts that go into the tips of an exhaust and don't stick out. They are not hugely effetive. But they cut 1-2 dB and don't hurt output. I'll see if I can find an URL for them.

EDIT: Found an example...but this one only is available down to 3 inch diameter. The Cone has many holes in it that total out to much more area than the pipe cross section. Minimal effect on output.

 

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Hmm.. a tip add on might be just the ticket.

The problem here is worsened because the rules say you can run again, if you made a mechanical change to the car. Those with supertrapps can say "I removed two plates" or someone else can add more packing. With our exhausts, there is nothing to do (except we "tightened up a loose diffuser fastener that might have been resonating") :rolleyes:

With a custom tip, I could have some options.

One other thought is a tip with a bend. Other cars do that here (though some think it is unsporting)....you attach the tips pointing away from the sound meter location.
 

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Wonder is someone with a stage II with exhaust tips pointing downward might squeak under the limits. Sounds like it's right on the edge, would be nice to have 1-2 db margins. Glad to hear a simple alignment made a difference.
 

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I'm going to try a test on my Stage 2 exhaust later today. If Randy's car hit 93 dBA at 50 feet this can be translated to other distances.

At 25 feet that would be +6 dBA or 99 dBA...at 12.5 feet: 105 dBA, at 6.25 feet: 111 dBA and at 3', 1 1/2 inches this would be about 117 dBA.

I have emailed the guy in the SCCA working on their noise rules and he relates that they are getting more pressure around the country about noise. This can affect site availability. The tests have to be setup to be fair and there are quite a few test factors to be considered. For example the MIC needs to be located in a spot where you can measure max SPLs from the intake/exhaust alone (intakes can be as loud or louder than exhausts on modified cars). But in some parts of a course cars can take somewhat different lines and this can affect the reading as you can see in the numbers above. You don't want to have spoiler scrape, cone hits or tire screech noises in the reading either. And you want average, steady type noise readings and not a 1/100th of a second spike, hence the use of the slow response scale. The neigbors almost always complain about the exhaust noise itself.
 

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We have a lot of technical stuff about meter placement that SCCA asked us to send to them. Elevation changes, hard objects behind the meter causing reflection...placement on a straight under (supposedly) full throttle, are all considered.
 

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Randy Chase said:
If there was some way they could take it down a notch like 1-2dB at 50 feet. That would be good.
Once your QS has 1000 miles on it may be 1-2 dbs quieter. But I'd rather not bet on that. We need to modify the exhaust to fully comply.

QS can make it quieter. No problem to achieve 1-2 dbs. Is that going to be enough?

They could also make the tips point down like Stage 2 if that might help. Personally I think we should just add more insulation to quiet the mutha down below the SCCA limit.

When do you think SCCA will finalize their sound requirements?
 

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>>>They could also make the tips point down like Stage 2 if that might help. Personally I think we should just add more insulation to quiet the mutha down below the SCCA limit. <<<<

Well you can angle the tips down a fair amount right now by just loosening the one clamp and then rotating the thing.

>>>When do you think SCCA will finalize their sound requirements?<<<

Whenever that occurs, it doesn't mean that you are all done. Some sites have local limits that can be quite a bit lower than what others may use as their limits.

It would be nice if QS used a slightly larger muffler can to cut dBs without any effect on output. And/or used a tip design which can take an insert to deal with events whose local SPL limit is lower than whatever the National limit turns out to be.
 

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Here are some of the Calclub sound rules... I think they use 93 dBA presently and that these may be the rules used at Qualcomm. Maybe they have been updated but you can get a sense of the concerns in any event..

"4.12 SOUND CONTROL. Purpose: Our primary purpose is to preserve the healthy competitive environment, which we all enjoy by maintaining a harmonious relationship with the community. It is our intent to provide sound control definitions and standards toward this end. Our organization, in making efforts to limit offensive noise emissions, wishes to demonstrate a desire for harmony with nearby residents, which in turn will reduce the likelihood of complaints and general intolerance of our sport.
4.12.1 GENERAL
4.12.1.1 This section shall establish CSCC SOLO II standards, test
procedures & instrumentation required for determination of vehicle sound emissions.
4.12.1.2 It is the competitor's responsibility to ensure that his vehicle complies with sound control regulations at each Event.
4.12.1.3 The Event Officials may offer advice to competitors. This advice, however, does not imply that any suggested corrective action(s) absolves the competitor from compliance with standards established by these regulations.
4.12.1.4 The Event Chairman or his designee may require a violator to pass a static (offcourse) test before being allowed to return to the course. Static tests will not supersede on-course measurements, because the full range of noises generated by the vehicle cannot be accurately measured statically.
4.12.1.5 Vehicle sound emission levels are variable. They are affected by factors such as temperature, humidity, wind, air density, etc. Therefore, sound emission may vary significantly from morning to afternoon and from day to day. Thus, a vehicle measured as marginally acceptable in the morning could exceed sound limits in the afternoon of the same day or at some future
Event.
4.12.2 STANDARD: The primary standard for CSCC SOLO II sound control shall be a sound pressure level of 95 dB "A" scale frequency weighted (dBA), measured on the fast response setting of the meter. {The rules committee of
CalClub has moved to change this to slow response.}
4.12.3 MEASUREMENT PROCEDURE: 4.12.3.1 General: Proper location and use of all test instrumentation is essential to obtain valid measurements. Operating Manuals or other
manufacturer's literature should be consulted to determine the recommended operating procedure.
4.12.3.2 PLACEMENT OF METER: All references to the "meter" with respect to placement shall concern the microphone portion of the measurement instrument (dB meter).
4.12.3.2.1The meter shall be mounted on a tripod and placed:
(a) 3.5 feet (min.) above the ground surface.
(b) 2.0 feet (min.) above the level of the course.
(c) 6 feet (max.) above the level of the course.
(d) 50.5' +/- 0.5' from the course side of the closest pylon, approximately perpendicular to the course.
(e) 200 feet or more away from any tunnel or overpass through which the target vehicle passes.
(f) 200 feet or more away from surfaces with high sound reflectance such as concrete walls, buildings or motorhomes.
4.12.3.2.2 Whenever reasonably possible, the sound measuring station should be located along a straight section of the course so that data is take while most cars are under maximum acceleration. An effort to avoid the influence, in measured data, of tire noise from nearby turns should be made.
Likewise, the equipment should ideally be measuring noise from only the object car. Care should therefore be taken to avoid influences from other cars on the course.
4.12.3.2.3 Ideally, the meter should be located on the outside of the course (i.e., between the car being monitored and the outside perimeter of the facility, aimed into the infield area).
4.12.3.3 TECHNIQUE:
4.12.3.3.1 The meter shall be located such that, when it is slowly rotated through 360 degrees, no background readings are greater than 80 dBA.
4.12.3.3.2 A battery check shall be made every hour.
4.12.3.3.3 Calibration shall be performed, before each Event, by the permanent custodian of the sound equipment or his designee.
4.12.3.3.4 A reasonable effort should be made to evaluate only non-tire noise. Tire squeal, such as can result from fast shifts and braking may cause a spike in the measured data. Such spikes should be ignored and, in the case where tire noise is mixed with other noise from the object car, an effort should be made to consider only the non-tire noise, as much as possible, in judging noise emissions for the car. Note: meters with a "maximum hold" feature may be better utilized, in the above case, with that
capability turned off (allowing the operator to observe the maximum level attained while eliminating any obvious spike from consideration).
4.12.4 EQUIPMENT:
4.12.4.1 A sound level measurement instrument (dB meter) which meets American National Standards Institute (ANSI) Specification S1.4-1971, Class 2, Type S2A or better, and provides the following features:
(a) Fast response setting
(b) "A" scale frequency weighting
(c) Demountable microphone (optional)
(d) Maximum hold (optional)
4.12.4.2 General accessories shall include:
(a) Tripod
(b) 50' (min.) steel measuring tape
(c) Operating manual
(d) Portable calibrator that is compatible with the meter being used.
4.12.4.3 All required equipment shall be available from CSCC Solo II
Committee, or their designee.
4.12.5 SOUND LEVEL LOG:
4.12.5.1 The sound level log shall be considered timing and scoring documentation and must be treated accordingly. (Ref. Section 5.8 and Section 6.5)
4.12.5.2 The sound level log shall contain:
(a) The number of the car being monitored
(b) The observed dBA reading for the car being monitored
(c) The make and model of the meter being used
(d) Battery test results (pass/fail) as taken every hour
(e) Weather conditions
(f) Name of operator
(g) Date of Event
(h) Event chairman
(i) Organization (Club, Etc.) providing Event Officials
4.12.6 RESULTS REQUIREMENTS: The results must identify all drivers whose runs were measured to be within 5 dBA of the limit and all drivers who have exceeded the limit. The results must also include the highest dBA value recorded for these drivers.
4.12.7 ENTRANTS ABOVE THE LIMIT: If a driver exceeds the limit, it will be the Event Chairman's responsibility, directly or through Event Officials he may appoint, to make sure that the driver corrects the problem before making any subsequent runs. The Static Sound Test procedure (Section 4.12.8.0) may be used, at the Event Chairman's discretion, for this purpose. Drivers will
not be red flagged for sound level infractions. If a vehicle is over the sound limit for three Events entered where sound is monitored, then that vehicle is banned from all CSCC sanctioned Events for the rest of the year.
4.12.8 STATIC SOUND TEST
(a) Place sound meter 15 feet behind the car and 45 degrees off the car's centerline, on the same side as the car's exhaust.
(b) Run the engine to 4000 RPM and take a sound level reading on the "A" scale. - OR -Run the engine to 4000 RPM as indicated on the tach supplied by the sound monitor. This meter is to be connected to the car by the entrant. The sound level reading is taken on the "A" scale.
(c) The entrant shall be given a minimum of one half (1/2) hour to fix the sound problem and return to the static test site. Note: Any fix must be safe for course workers and spectators, as well as the driver. The use of steel wool in the exhaust system, or drink cans inadequately attached to the exhaust pipe tip are examples of fixes that have proven to be unsafe in the past.
(d) Repeat steps A and B. The difference between the first static test reading and the second static test reading must meet or exceed the difference between the oncourse reading and the Event dBA limit.
4.12.9 OTHER SOUND SOURCES: Objectionable sounds from sources other than cars on the course can also be a problem. The thoughtful placement of the P.A. system and the control of engine and tire warm-up activities should minimize objectionable sound from these sources.
4.12.10.0 SITE SURVEY
4.12.10.1 SITE SURVEY COMMITTEE: The CSCC SOLO II Executive Board shall appoint a committee consisting of not less than two (2) persons to evaluate the noise sensitivity of all SOLO II sites. As a minimum, the following factors shall be considered:
4.12.10.1.1 The stated requirements or desires of the property
owner/manager.
4.12.10.1.2 The proximity of residences. When appropriate, a survey should be made to subjectively evaluate sound levels in nearby residential areas
resulting from 95 dBA sound originating at the SOLO II site.
4.12.10.1.3 Nearby sources of objectionable sound which could make the SOLO II sound levels seem "insignificant". (Examples - nearby airport, street noise, etc.)
4.12.10.1.4 The existence of ordinances regulating maximum sound levels at some specified point of reference, i. e. the property line.
4.12.10.1.5 Consideration should be given to course workers and spectators for possible hearing discomfort.
4.12.10.2 Using site survey data, the CSCC SOLO II Executive Board shall place each SOLO II site into one of the following categories:
4.12.10.2.1 NOISE CRITICAL: Sites, the use of which, would probably be in jeopardy if an Event were to produce noise only slightly above existing ambient levels. Noise must be measured at a noise critical location.
4.12.10.2.1.1 Procedure: Sound level readings shall be made and a log sheet kept, constantly, throughout the Event (ref. Section 4.12.5). Readings of 90dBA or above shall be reported in the results (ref. Section 4.12.6). Strict adherence to the 95 dBA limit shall be mandatory. Flyers will state: "Closed exhaust. The 95 dBA noise standard will be monitored and strictly enforced".
4.12.10.2.2 NOISE SENSITIVE: Sites where noise originating at the Event which is somewhat louder than ambient but not overwhelming would be acceptable.
4.12.10.2.2.1 Procedure: The 95 dBA noise limit applies but continuous sound level monitoring throughout the Event will not be required. Sound measuring equipment shall be available. This is to accommodate testing of specific cars either because of particularly annoying noise suspected to be above the 95 dBA limit or by driver request for an advisory reading. A suitable sound
monitoring station location should be identified (ref. Section 4.12.3.2).
Flyers will state: "Closed exhaust. The 95 dBA noise standard may be monitored".
4.12.10.2.3 NOISE TOLERANT: Sites where considerable noise is acceptable. Noise may be measured at a noise tolerant location.
4.12.10.2.3.1 Procedure: Open exhaust may be allowed (no exhaust muffling required). Flyers will state: "Open exhaust allowed in accordance with class preparation rules. The 95 dBA noise standard will not be monitored".
 

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Reto, trust me-the QS is louder. It really, truly is.

I wonder if I'll face sound limits on Sunday in PA? yikes!
 

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How about simply adding a pair of 45 deg *turn down* tips to aim the wave to the ground so that it is broken up?
m
 

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Discussion Starter #17
I have been thinking about that. I think we are louder to the meter because our tips stick straight out the back.
 

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Maybe I'll fashion some tin foil tips with garbage bag ties to take with me Sunday and put on the car in case of emergency.

Cripes this is dumb. The SCCA is starting to remind me of the PA department of motor vehicles!:rolleyes: :huh:
 

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>>>Maybe I'll fashion some tin foil tips with garbage bag ties to take with me Sunday and put on the car in case of emergency. Cripes this is dumb. The SCCA is starting to remind me of the PA department of motor vehicles! <<<

You'll be okay in PA. Many of the SCCA regions don't even measure SPLs at all. Qualcomm is the place where the SCCA is developing their noise control strategy, techniques and so forth while building experience that will help them long run.

If the QS is a single exhaust inside the muffler can (it appears to be) then you should get a safe, measurable sound reduction by clogging up one pipe ~100 %. You need to do this well enough that the cover/stuffing will stay on during the runs. Perhaps use some steel wool in the tip covered with fiberglass cloth wrapped around the stuffed tip itself. Then you could retain the cloth around the tip by using a couple of hose clamps. Maybe even safety wire the clamps to something upstream. That way the stuffing stays in and nothing gets marred or scratched. Two clamps will definitely hold it for an autocross as I have had to do this in the past in my M3. If you just stuff it in it's likely to pop out.
 

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If only I had some fiberglass cloth laying around.

Is it safe to stuff steel wool in the exhaust? Sounds like a potential fire.

I think you're correct on the noise thing in PA. At least at the last autoX in Nazareth, there were a couple of cars running with no mufflers-talk about loud! And Perry and Brian were talking about running a straight pipe at the state championships, so I guess you're right.
 
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