Jump to content
Yelmarb

Recording race car engine and exhaust sound at speed

Recommended Posts

Yelmarb   

I'm trying to get a true sound of a race car going up through its gears but I'm finding it much harder than what I thought. To get the sound I want I need to mix both engine and exhaust notes.

I know some productions have been able to get the car on a dyno but unfortunately we can't get the car to one so it has to be done on a race track.

I've tried mounting lav mics (with fluffy wind jammers) in secluded sections of the engine bay and under partially secluded sections of the back of the car but the wind still just pummels them. The engine bay is a nightmare as the mics are hammered by the airflow but also from the heat of the engine which is like a furnace.

I've then tried mounting a shotgun mic in a blimp and fluffy wind jammer on the exterior of the car but again the wind at 70mph and above just overrides that combo. So I haven't managed to get a decent recording at anything past 2nd gear. Ideally I need to get all 6 gears which means the car would be nearing 200mph.

Has anyone successfully done this? If so, could you please share you knowledge.

Share this post


Link to post
Share on other sites

Try a dynamic (I use sennheiser 835s) mic, in a windjammer (or a sock) mounted to the underside of the car in an area that is protected from the wind. Sanken CUB's are great for this too, you can typically get them in a wind protected pocket that would be too small for a dynamic, but you'd still need a wind sock. Make sure the cable is VERY well secured!!!

It's going to be very difficult to do this - are you sure there's not a dyno AT the race track?

Share this post


Link to post
Share on other sites

" are you sure there's not a dyno AT the race track? "

these sounds are usually best left to post...

OK, maybe you are post ?? ??? this stuff typically takes a lot of experimentation, even for those with experience at it, especially since there are so many differences amongst the "subjects".

Share this post


Link to post
Share on other sites
jrd456   

I did it successfully by mounting shure SM57's with gaffers tape on rubber foam all over the race cars.It's best to use a dynamic mic. if you don't want any trouble once you get out on the track,they can handle the SPL.

J.D.

Share this post


Link to post
Share on other sites
dfisk   

AHhhh...Finally something I've done a ton of....

I did a BUNCH of car recordings for EA's Need for Speed franchise. We would record cars on the dyno, and then on the track. For track stuff we usually did 4 to 6 tracks of audio. 2 to 3 mics in the engine compartment, and 2 to 3 mics on the exhaust. You'll want to use hardwired omni lavs for the engine compartment, and wrap the crap out of them in any sort of foam. I usually used spare "pick-n-pluck" foam from a pelican case. You'll need to use lavs that can handle high SPL's, like the MKE-2 platinum lavs. AT makes some good ones for this application as well. Put one lav on the air intake. One lav up against the firewall, and if you can, try and fine a sweet spot somewhere on the underneath side of the hood, right above the engine.

Now for the exhaust. I've mounted a 57 on a bogen magic arm and pointed it right at the tail pipe. I've done the same with a 421. I'll usually wrap a lav in a bunch of foam (like I did for the engine), and tape that to the bumper right above the tailpipe. Usually with race cars and heavily modified cars, getting close enough is good enough to get a good sound. These things are so loud that putting anything within a foot or less of the tailpipe will work. It's the engine compartment you have to get picky about.

If you can...put some lavs in the wheel wells. Again, wrap them in foam and tape the crap out of them to stay put inside the wheel well. You'll get some cool tire sounds. Just make sure you have a recorder with enough tracks to handle it all.

Share this post


Link to post
Share on other sites
Yelmarb   

Wow, thank you dfisk! That's a brilliant reply. Fluffy wind jammers become useless at high speed. I never thought to add more foam, great idea. I have a couple of MKE-2's that I can hardwire.

Brilliant idea on using multiple locations within the engine bay too. How did you go about shielding the lav's wrapped in foam from the heat of the engine?

Did you pick up any wind noise from the magic arm mounts (i.e. wind noise you'd hear if you put your hand out the window of a moving car)?

Thanks jrd456 - assuming the rubber foam you were using was quite dense?

Share this post


Link to post
Share on other sites

" are you sure there's not a dyno AT the race track? "

these sounds are usually best left to post...

To quote you, "it depends". I can think of numerous situations where it's not posts job to get those recordings, and it sounds like the primary goal of the op is to get a good recording, so that makes it his job, not someone else's.

I second the use of 57s, and in general hard wired dynamic mics or lavs where the larger dynamics won't fit. I had good success on a Shelby cobra replica last year mixing exhaust and engine mics with a bit of tire. The tempatures get quite high in the engine compartment, I melted a mic cable and the mic mount, but it didn't matter cause I had it strapped, taped, and secured every which way I could imagine.

I also tried to find and isolate the different sounds in the engine, valves, exhaust manifold, etc and then mic each one.

I recommend telling them you need to be in the car to monitor, that way you get to go flying around the track at 200mph :-D

Most of all, have fun!

http://wanderingear.net

Share this post


Link to post
Share on other sites
Yelmarb   

Thanks Wandering Ear! Indeed it is my job to get this recording. And there are certainly no dynos at race tracks that I've been to. I did try to sit in the car and monitor but I ended up so car sick that I had to sit in the corner of the pit garage for about an hour afterwards while the rest of the crew made jokes. So it will just be my Nomad that goes along for the ride next time.

Were you not worried about the mic's being damaged as well from the heat of the engine? I'm a little concerned about wrapping the mics in loads of foam with the possibility that they could catch fire inside the engine.

Race cars don't exactly have the smoothest of rides, did you use any isolation when mounting the SM57? Also, how did you protect it from the wind?

Share this post


Link to post
Share on other sites

I used to have a Shure SM11 (dynamic lav) and used it in tight spaces with high SPLs. Unfortunately it met an early demise in an engine compartment. As robust as it was, no match against belts, pulleys and such.

Share this post


Link to post
Share on other sites
dfisk   

Wow, thank you dfisk! That's a brilliant reply.

Did you pick up any wind noise from the magic arm mounts (i.e. wind noise you'd hear if you put your hand out the window of a moving car)?

In terms of heat, I never had an issue, but we never ran the cars on the track for any longer than 15 to 30 minutes, depending on what we needed....and how fun the car was to drive. :)

I mounted the magic arms to the undercarriage of the car at the rear, so it is pointed right at the exhaust. If it's a side exhaust, then I mount it on the undercarriage and have the back of the mic pointed towards the front of the car. That can help sometimes, but if that doesn't work, I've used the "coffe can trick". This isn't optimal, but on really loud exhaust is works fine. Basically you do this (again, this is for side exhaust, where the pipe is under the door):

-Get an empty coffee can. Remove the lid.

-Cut a hole in the bottom of the coffe can.

-Put a 57 in the coffee can, and wrap the 57 that is in the coffee can in a bunch of foam. Run the cable out the hole you cut in the bottom.

-Wrap the whole can in foam. This will act as a pseudo shock mount.

-Tape this to the side of the car. Important note***USE PAPER TAPE*** If you use Gaff tape you will leave residue, and that is not good. Use a LOT of tape.

-Now the tricky part...Get a piece of cardboard, and tape it around the can, but make it so it kind of ramps down from the side of the can to the car, making a smooth edge, like if you were putting a kind of spoiler on the side of the car. This allows the air to move smoothly over the can, rather than getting a bunch of wind noise hitting the bottom of the can. Tape that liberally.

-Tape down the cable very well. Since you are basically going to have this thing pointed down and at an angle towards the side exhaust, you need to make sure the mic is very snug with extra foam inside the can, and gain...tape tape tape.

If you do it right, you eliminate any wind noise and vibration. Make sure you give yourself lots of time to rig up the cars. We'd sometimes spend an hour wiring up one car to make sure we do it right. I wish I had pictures of what I've done in the past, but I don't. The one thing I've learned about recording cars, is that all the normal rules go out the window, and you have to get creative.

Oh...one more thing..you can get a dyno to the track. I've done it. It needs to be a "dyna-pack" which isn't a drum dyno, but an axle dyno. It's great because you can hook the cars computer up to the dyno computer and have it run steady rpm's for a set period of time. For games, that was really important. It's hard to get steady RPMs while driving.

Share this post


Link to post
Share on other sites

I can attest to the "dynamic mic in a coffee can" rig working well. Used the same technique on a radio spot for a high end car dealer and spent a day at the track recording Ferraris, Aston Martins, Maserati, and Bentleys. Back of the car ( these were all rear exhausts ), low down sounded great. Mounted some of my rigs with long, industrial strength tie wraps. Many of these cars have really smooth diffusers and bottoms for aerodynamics at the back, so be prepared to get creative with mounting.

+1 on all the engine compartment advice.

As was stated- rules out the window ! One of the most fun and satisfying days in my career. Nothing like a wailing 12 cylinder.

Share this post


Link to post
Share on other sites

Were you not worried about the mic's being damaged as well from the heat of the engine? I'm a little concerned about wrapping the mics in loads of foam with the possibility that they could catch fire inside the engine.

Nope. That's why I used 57's. If I lose them, that's just what it costs to get good sound. Production insurance, or the production will pay for that, and I told them I would use less expensive and durable mics to try and avoid the damages.

I used lot's of fur, baffling, and placement to deal with the wind, although I was never going any where near 200mph. I think we topped out at 70ish as we weren't on a race track. For mounting options I had a bunch of mafers, cardalinis, short arms, lots of tape, and I used short cables to safety the mics in case any of my mounts and tape failed, the same way grips do with hanging lights.

I did end up shortening my XLRs that went into the engine compartment, because they did start to melt. I used one of the plastic mic clips that comes with a 57, and melted that too. I believe Mogami makes some high temp cabling, but I've never tried it. Limit your exposure times and you can probably get away with it no problem.

post-2639-0-76125700-1333138329.jpg

I've only ever tried the coffee can trick with a contour HD camera mounted on a bicycle, but I'm going to keep that in my bag of tricks for the next time I get myself into some crazy micing situation. (hopefully soon!!)

Have Fun.

K

Share this post


Link to post
Share on other sites

" I can think of numerous situations where it's not posts job to get those recordings, "

me, too, so that is why I qualified my comment with " OK, maybe you are post ? ".

That would include being hired specifically to record these sound effects.

It is complex, and depending on tastes, may require a lot of trials and errors, and could cost the production company for ruined equipment. Personally, I'd go with an MD-421 over an SM-57...

Also, personally, I would prefer not to ride. :wacko:

Share this post


Link to post
Share on other sites
dfisk   

Sometimes it is up to post. When I was at Danetracks, we did lots of sound effects recording sessions.

Share this post


Link to post
Share on other sites

" Sometimes it is up to post. "

of course, and then there is the potential that " a true sound of a race car going up through its gears " isn't as good as an enhanced true sound...

Share this post


Link to post
Share on other sites

" Sometimes it is up to post. "

of course, and then there is the potential that " a true sound of a race car going up through its gears " isn't as good as an enhanced true sound...

And still irrelevant to the OPs question.

Share this post


Link to post
Share on other sites

Hi,

Thanks for all the info posted here: it gave me very practical advice and ideas that I had a chance to just try out.

I worked yesterday on a WSJ short doc in Tucson, featuring a Shelby Cobra. The car is to be auctioned next week in Monterrey (expected price it will fetch, $2.5 million).

In a  nutshell: the car people were very wary about where the camera and mics went. I was excited to try the coffee can trick but ended up wrapping a Shure SM57 in foam and zip tying it to the driver's seat bar.

The mic pointed down to the fiberglass floor, several inches above one of the two exhausts.

Attached is a sample from the shoot; any feedback welcome.

best,

 

Mike

IMG_1999.JPG

ShelbyCobra_demo.wav

Share this post


Link to post
Share on other sites
mikewest   

Done lots of this always with dynamic mikes

Also iso tracks allow engine/exhaust/interior in stereo/ plus exterior vehicle all at once

mike

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×