Noise measurement - Ford Kent

[DuncM]

Does anyone have good db noise measurement data for a typical Ford F1600 with no muffler?

My local track, Le Circuit Mont Tremblant, has been forced to institute limits.

Duncan Murdoch

[billtebbutt]

What limit are they using?? Enough people on here with enough experience with this, given that info, to tell you what you'll need to do

bt

[DuncM]

What limit are they using?? Enough people on here with enough experience with this, given that info, to tell you what you'll need to do

bt

The limit is 92 db. I believe it is measured at 40 ft but not sure of this distance.
Duncan

[beavertail]

Pole Position magazine recently reported on the sale of Circuit Mont Tremblant, and noted that the noise limit has been set at 96db
https://www.poleposition.ca/actualit...-proprietaire/

[DuncM]

Pole Position magazine recently reported on the sale of Circuit Mont Tremblant, and noted that the noise limit has been set at 96db
https://www.poleposition.ca/actualit...-proprietaire/

Requirement direct from the track is 92 db. The article was incorrect.

[jrh3]

There are free noise measurement apps for your phone available. Might give you an idea of how your muffler is doing. Unfortunately, I deleted it and can’t help with specifics.

[Lastminuteracin]

I can tell you from dealing with Laguna Seca that 92 is pretty quiet. You will definitely need some sort of muffler.

[David Ferguson]

A FF with no muffler is going to be 100+ dB. You'll need a good (large) muffler to reach 92dB, geometric volume is what will reduce the sound without reducing the power.

[Jim Edmonds]

Arizona Motorsports Park has had a 96dba at 50' limit for more than a decade. On a 1600 Kent a short Supertrap muffler with about a dozen plates will meet this requirement with no problem.

A 2 liter Ford FC can also meet the requirement with this setup.

Increase the number of plates until you don't meet sound, then take two out.

The Supertrap does reduce horsepower a significant amount. I'd guess 8 to 10 percent. It is enough that the decrease in horsepower does affect the full throttle handling of the car.

YMMV. I suspect a properly designed aftermarket muffler wouldn't cost as much HP. We went the Supertrapp way to make it equal for all FF's, so we can race. This also works on 1500 Honda Fit powered cars.

It doesn't work on the motorcycle engine Legend cars. Too much noise from the engine itself.

Have fun,

Jim Edmonds
Phoenix, AZ

01 Van Diemen FF
13 Elan USF2000
95 Stohr F3
17 MV Agusta track bike,
etc.

[DuncM]

A FF with no muffler is going to be 100+ dB. You'll need a good (large) muffler to reach 92dB, geometric volume is what will reduce the sound without reducing the power.

Thanks...that's what I was expecting and afraid of.

Does anyone know of another track with a 92db limit and the specific muffler to meet it?

[DanW]

Exhaust is the major source of noise, but so are other parts of your car. Noise is cumulative from all sources.

Intake roar, gearbox noise from your Hewland.

First, point the exhaust outlet away from the microphone set along side the track.
The Supertrapp muffler with the fiberglass packing works better than the disc model alone, but not sure you could make 92dB with it alone. It might work with a muffler upstream of it. The longer the better.

Burns Stainless makes a two stage race muffler. Very light but also lightens your wallet. It makes a small HP loss of 2-3 HP.

I tried one of the Burns two stage mufflers along with a single stage muffler after it. Both were packed with fiberglass, several dB more quiet than using the stainless scrubble they come with. https://burnsstainless.com/products/2-stage-mufflers

Intake roar from your carb can be fixed with an airbox that also points away from the microphone. There's a surprising amount of noise coming from a Weber 32/36DGF at 6500 rpm.

I received a "sound jeopardy" warning at Laguna years ago. One of the other drivers mentioned he could hear my gearbox whine going up the hill from Turn 5. I discovered third gear was near failure from spalling. I replaced the gearset and the noise warnings went away.

[TimH]

Intake roar from your carb can be fixed with an airbox that also points away from the microphone. There's a surprising amount of noise coming from a Weber 32/36DGF at 6500 rpm.

More like intake Shriek. When I went from CF and an open foam intake to a more modern engine cover with intake behind my head I suddenly discovered the need for ear plugs to avoid pain above 5500.

[alangbaker]

More like intake Shriek. When I went from CF and an open foam intake to a more modern engine cover with intake behind my head I suddenly discovered the need for ear plugs to avoid pain above 5500.

I remember being told that I'd need ear plugs for my FF (a modified RF89 Van Diemen) with its intake from right behind my helmet...

...and it took only a single event for me to agree.

[TimH]

Does anyone know of another track with a 92db limit and the specific muffler to meet it?

I'm pretty confident Marcel is looking into it. He needs that track for his series.

[tstrong]

Exhaust is the major source of noise, but so are other parts of your car. Noise is cumulative from all sources.

Intake roar, gearbox noise from your Hewland.

First, point the exhaust outlet away from the microphone set along side the track.
The Supertrapp muffler with the fiberglass packing works better than the disc model alone, but not sure you could make 92dB with it alone. It might work with a muffler upstream of it. The longer the better.

Burns Stainless makes a two stage race muffler. Very light but also lightens your wallet. It makes a small HP loss of 2-3 HP.

I tried one of the Burns two stage mufflers along with a single stage muffler after it. Both were packed with fiberglass, several dB more quiet than using the stainless scrubble they come with. https://burnsstainless.com/products/2-stage-mufflers

Intake roar from your carb can be fixed with an airbox that also points away from the microphone. There's a surprising amount of noise coming from a Weber 32/36DGF at 6500 rpm.

I received a "sound jeopardy" warning at Laguna years ago. One of the other drivers mentioned he could hear my gearbox whine going up the hill from Turn 5. I discovered third gear was near failure from spalling. I replaced the gearset and the noise warnings went away.

I use the supertrapp shorty (approx 8”) glass pack with no plates (open straight through) and meet 96 at laguna without issue on several occasions. 92 is a big reduction. I would suggest trying the 18” supertrapp with no plates and a 90 turn away bolted to the end as Dan mentions. Also need to address intake noise for sure. My guess (but just a guess) is this would get you in the ballpark. Todd

[DuncM]

I use the supertrapp shorty (approx 8”) glass pack with no plates (open straight through) and meet 96 at laguna without issue on several occasions. 92 is a big reduction. I would suggest trying the 18” supertrapp with no plates and a 90 turn away bolted to the end as Dan mentions. Also need to address intake noise for sure. My guess (but just a guess) is this would get you in the ballpark. Todd

My car is a late model VD with full rear bodywork & intake scoop so I suspect the intake noise would be attenuated to a large degree.

Unfortunately given the situation there is no latitude for trial & error. If you fail you go home. Therefore I am hoping for guidance from someone who has achieved 92 db and how they did it.

[DanW]

"there is no latitude for trial & error. If you fail you go home." We are under the same regulation but a higher sound level for a race weekend. If we want to do a track day at Laguna Seca, we need to meet 92dB A as you do. Most sportscar/performance aftermarket exhausts will blow 92dB. Days with low clouds will reflect sound back to the ground. If you are at 91dB, the clouds could put you over. Reflections from buildings, walls or earth embankments will also affect sound. So, target 90dB if you can.

One might consider using a passenger car muffler from a car of similar or slightly larger displacement and see how it works at relatively low cost. Unless you're an acoustics engineer or have access to one, it's pretty much an iterative process. It might help to line your carb intake with a layer of filter foam to help further.

If you want to measure the sound your car produces before you get to the track, you can rent a sound pressure level meter from some industrial rental vendors. These should be calibrated instruments and should get you very close as long as they are set the same as how the track sets their instrument. Usually they are set to "Fast" response, "Peak", on the 'A' Scale.

The other method is an iPhone app called SPLnFFT. It uses the microphone to measure and indicate the sound pressure levels. I found the app on my phone reads about 1-2 dB high on the "A" scale. That should at least get you an idea of the sound levels. Be sure to measure the peak value at the distance the track specifies. Do multiple passes at max rpm (10 is a decent number) to get repeatable data. I think the app sells for about $10 or less.

Good luck.

[Gary Godula]

Duncan,

At Waterford Hills in Michigan, the sound limit is 75dB at the property line along the back stretch, less than 30 ft from the track surface and the racing line. We are using a shorty Supertrapp motorcycle muffler which has a 6" length of fiberglass packing and approximately 18 plates to meet that limit. The overall muffler length minus discs is less than 10". We do not have the option to redirect the sound away from the property line/meter with this package. We have an open foam ITG air filter with no snorkel or shielding, so no real redirection there. The gearbox on the Reynard is a unique casting and is usually pretty quiet.

For tracks with 98 or 100 dB limits, we usually use a turned exhaust tip to direct the sound away from the property line/meter and do not use a muffler. For anything below 98dB, we use the Supertrapp with packing, and can usually pass 98dB without discs.

Per several engine builders that I have talked to, most good FF Kent engines make 102dB at the tailpipe. If you find one making 103dB, tear it down as it is probably illegal.

Waterford Hills issues sound warnings at 74dB with a furled black flag and a sound board at start/finish. A full black flag is issued at or above 75dB. Sound readings are usually posted with the qualifying/race results. We are given the opportunity to correct the car, but a second violation or flagrant violation will result in disqualification. Does Mont Tremblant have a similar process or policy?

Let us know what you decide to go with for your sound-abatement package. Good Luck.....

[DuncM]

Duncan, &lt;br&gt;<br>
&lt;br&gt;<br>
At Waterford Hills in Michigan, the sound limit is 75dB at the property line along the back stretch, less than 30 ft from the track surface and the racing line. We are using a shorty Supertrapp motorcycle muffler which has a 6" length of fiberglass packing and approximately 18 plates to meet that limit. The overall muffler length minus discs is less than 10". We do not have the option to redirect the sound away from the property line/meter with this package. We have an open foam ITG air filter with no snorkel or shielding, so no real redirection there. The gearbox on the Reynard is a unique casting and is usually pretty quiet. &lt;br&gt;<br>
&lt;br&gt;<br>
For tracks with 98 or 100 dB limits, we usually use a turned exhaust tip to direct the sound away from the property line/meter and do not use a muffler. For anything below 98dB, we use the Supertrapp with packing, and can usually pass 98dB without discs. &lt;br&gt;<br>
&lt;br&gt;<br>
Per several engine builders that I have talked to, most good FF Kent engines make 102dB at the tailpipe. If you find one making 103dB, tear it down as it is probably illegal. &lt;br&gt;<br>
&lt;br&gt;<br>
Waterford Hills issues sound warnings at 74dB with a furled black flag and a sound board at start/finish. A full black flag is issued at or above 75dB. Sound readings are usually posted with the qualifying/race results. We are given the opportunity to correct the car, but a second violation or flagrant violation will result in disqualification. Does Mont Tremblant have a similar process or policy? &lt;br&gt;<br>
&lt;br&gt;<br>
Let us know what you decide to go with for your sound-abatement package. Good Luck.....

Thanks to all for the info so far.
The upcoming September Fall Classic will be the first race event with this restriction. However for their other lapping and DE days apparently they have been understandably severe in application since the law suit. Based on second hand reports, black flag for first exceedance, exclusion for the second. I suppose the Supertrapp provides the only option with some level of adjustability, presumably at the cost of significant power loss.
Duncan

[DuncM]

Thanks to all for the info so far.
The upcoming September Fall Classic will be the first race event with this restriction. However for their other lapping and DE days apparently they have been understandably severe in application since the law suit. Based on second hand reports, black flag for first exceedance, exclusion for the second. I suppose the Supertrapp provides the only option with some level of adjustability, presumably at the cost of significant power loss.
Duncan

As a point of reference does anyone have the noise level of a Zetec F2000 before and after installation of a Coastfab or Burns muffler?

In the UK they use a homologated muffler for FF but I cannot find the noise limit achieved. Does anyone know?

[problemchild]

As a point of reference does anyone have the noise level of a Zetec F2000 before and after installation of a Coastfab or Burns muffler?

Duncan,
The Zetec engine is much noisier than a Kent, certainly at its peak volumes. If somebody has a muffler solution for a Zetec, it should certainly handle the Kent.

[DuncM]

Duncan,
The Zetec engine is much noisier than a Kent, certainly at its peak volumes. If somebody has a muffler solution for a Zetec, it should certainly handle the Kent.

Thanks Greg
My thinking is the delta between before and after should be a good indication (slightly greater than) of what is achievable on the Kent.

[RSS]

As a point of reference does anyone have the noise level of a Zetec F2000 before and after installation of a Coastfab or Burns muffler?

In the UK they use a homologated muffler for FF but I cannot find the noise limit achieved. Does anyone know?

Zetec without a muffler is in the 105-110 range with a coast fab it will drop you to around 98-100.

I just looked up the price of those burns ones!!

[DuncM]

Zetec without a muffler is in the 105-110 range with a coast fab it will drop you to around 98-100.

I just looked up the price of those burns ones!!

Thanks
That is a wide range of 5 to 12 db reduction.
My logic...if I was to assume 80% of that reduction is possible on the Kent = 4 to 9.6 db reduction from 100 db for a typical Kent results in 90.4 db to 96 db

If anyone could provide a narrower range for the Zetec that would be helpful.

Yes I saw the pricing on the Burns too

[RSS]

There where 3 different sound stations around the track so different measurements depending on throttle position side of the car location etc lead to the larger range.

All measurements where at around 15' from the vehicle.

[DuncM]

There where 3 different sound stations around the track so different measurements depending on throttle position side of the car location etc lead to the larger range.

All measurements where at around 15' from the vehicle.

Thanks for the clarification.

Then it may be reasonable to assume the values are high point to high point and low to low... so the range of reduction is 7- 10 db.