removing engine cover = no more drone?

Yesterday I pulled my spare tire out and engine cover off in preparation for the new SOS Supercharger with Laminova IC.

I took the car for a spin and immediately noticed that my drone in the 2k - 3k range virtually disappeared. Whatever drone that might be left is faint compared to the exhaust sound from the rear of the NSX.

I confirmed this by opening and closing my windows. Also, even drove the car in tunnels, over pass and garages.

Anyone else experienced this?

Mac Attack?

RYU?

beuller? beuller?

Yessur I have I have a stock NSX that I put the engine cover back on and noticed the drone,so I removed the engine cover and it will likely never go back on.

I wonder what's the science behind this drone and engine cover.....

I'm tempted to try this out...but no engine cover = fog in rear hatch when it rains :frown:

dablackgoku1234 said:

I'm tempted to try this out...but no engine cover = fog in rear hatch when it rains :frown:

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Really?

I pressure washed the engine bay and it all evaporated out.

Interesting. I have never tired that, but with the t-top I want my cover on. My golf clubs are normally in the trunk.

Hmmm going to have to test this theory...never thought about the cover having something to do with the drone...but hey...you never know...:tongue:

when i looked through the rear view mirror I can see the vents between the hatch and trunk lid.

I wonder if this might have anything to do with this.

How about some audio clips with cover on and off? I haven't ever noticed any drone but I guess I haven't really been listening for it.

Dhalsim said:

How about some audio clips with cover on and off? I haven't ever noticed any drone but I guess I haven't really been listening for it.

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U should do it, might be diffferent results since mufflers are different.

NetViper said:

Interesting. I have never tired that, but with the t-top I want my cover on. My golf clubs are normally in the trunk.

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Targa NSX ( or anything for that matter)?

My condolences.

BATMANs said:

U should do it, might be diffferent results since mufflers are different.

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That's ture. My Taitec GT Lightweight exhaust makes pretty loud drone during 2000rpm to 2500 rpm. I'll try to remove the engine cover next time.

Interesting...

Drone is caused by some source (usually something loud like an exhaust frequency) that excites a particular part of a vehicle that has a natural frequency in that range (think vibrating champagne glass that vibrates, etc).

The drone you must have heard Batman was the cover that had a natural frequency in the 100-200Hz range.

You can experimentally determine an objects natural frequency by suspending it and sharply striking it with a hard hammer while sampling the sound generated with a spectrum analyzer. It should have a specific resonance peak.

The cover could also act to change the volume of "air" trapped under the engine bay. This engine bay "volume" may have a specific resonance around that frequency too. Since that's a little harder to figure out, it's easier to first do the hammer test described above.

Thanks for posting that - I never would have thought about that potential impact.

For example - I have a lexan divider window and that thing shakes like crazy in my drone region (105Hz). If it's the air volume in the engine compartment, maybe I could ADD my cover back on to shift the resonance... Hmmmm - too bad I got rid of it a long time ago.

Dave

Mac Attack said:

.......The cover could also act to change the volume of "air" trapped under the engine bay. This engine bay "volume" may have a specific resonance around that frequency too.......

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That sounds tantamount to rolling one window down and the far side of the cabin has the drone.

interesting.. i might have to test it out tomorrow.. my cantrell drone around 2500rpm. Less now that i have ctsc and test pipe..a lot of drone with stock cats though..

SUBSCRIBED!!

dablackgoku1234 said:

I'm tempted to try this out...but no engine cover = fog in rear hatch when it rains :frown:

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I've had a mesh engine cover for about 10 years now and I have never had a fogging of the rear hatch, nor have I noticed any difference in engine drone.

My car doesn't drone now so I can't say I've observed this :smile:

I have the same thing with my CTSC 2004 , the after market targa compartment makes noise when starting.

Brylek said:

I have the same thing with my CTSC 2004 , the after market targa compartment makes noise when starting.

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Which one do you have? pics?

I have the one with zippers on the sides if it helps, i will try to post a picture later. I solved the problem, i put vacuum line plugs on top of the lower outside engine brace screws and it does not make any sounds anymore. I basically raised the targa compartment on rubber bushings

Brylek said:

I have the one with zippers on the sides if it helps, i will try to post a picture later. I solved the problem, i put vacuum line plugs on top of the lower outside engine brace screws and it does not make any sounds anymore. I basically raised the targa compartment on rubber bushings

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Got a pic?

I did this, it eliminated most of the drone. I will get longer plugs which should solve the problem compleatly.

No updates?

I eliminated most of the drone by using the those vacum line plugs shown above but I am confused now. I also removed the targa compartment to see what would it be like and i still get some of the sounds. At this point i think it is not the targa compartment/engine cover that is producing the drone, maybe i'm wrong?

I have the cantrell type-r style engine cover and I still get drone....but its not as noticeable unless I drive for a long time.