Super Quite Aircooled!! Is It Possible?

[Astromic]

hey,
what is the reasons and solution of decreasing the loud aircooled engine(not exhaust stuff, internal stuff), i heared that heavy-valvtrain is noisy, and push rods is a noisy part if not choosen carefuly, i heared too that the stock valve adjusters is noisy and the swivle type is more quiter...
there is also sound-substracting materials some ppl put around the gearbox and the rear engine cover...
i'm talking in the engine only, not the exhaust parts, because it's easy to replace any muffler with quiter one...

what do u think of this and what parts should be replaced with what to reduce the engine sound as much as possible ?

Michael

[Steve Arndt]

Big lift at the cam is noisy.
Minimise rocker arm side play to minimize noise.
Aluminum pushrods are quieter compared to cromo.

I'm sure the thick/heavy aluminum aftermarket blocks are quieter than a stock as41 case.

just a few thoughts.

[Astromic]

there's a head cover i saw it before in some site(don't remember where exactly) wich made of sound consumption materials, did any one tried those?

[vwdmc16]

hyd lifter would help too

[BergRace]

there's a head cover i saw it before in some site(don't remember where exactly) wich made of sound consumption materials, did any one tried those?

Carefull with those, alot of heat disipates from the oil through the valve covers on the boxer engines, that is why chrome is a no no..Likwise carbon fibre..

J.

[Astromic]

i found a car two weeks ago, it's owner replace the engine cover wit a "transparent" carbonfiber one,,,he want only the look of the chromed engine to appeare but it helped alot with the sound,,, i was really stunned when he opened the cover and heared the difference,,, i'm now on planning to convert some parts in my car to CF wich reaqlly help in many ways like rust(my town is a rust-place ), light weight and the sound absorb-ability...

Michael

[Astromic]

well, that's new, i found here in this site that longer rods makes the engine overall sound quiter...
http://www.popularhotrodding.com/tech/0 ... amper.html

Michael

[krusher]

if your talking about the sund level you hear from the drivers seat i would not look to making the engine quiter but to sound proofing the body, using vibration and sound deadeners like dyno matt.

also http://www.secondskinaudio.com/cgi-bin/index.cgi

[krusher]

if your talking about the sund level you hear from the drivers seat i would not look to making the engine quiter but to sound proofing the body, using vibration and sound deadeners like dyno matt.

also http://www.secondskinaudio.com/cgi-bin/index.cgi

your never going to make an aircoled very quiet as it has no water jackets witch absorb sound in water cooled cars.

[MinamiKotaro]

Indeed, use Dynamat or some other such substance. It will add some weight but, let's be honest, that wonderful "BWAHHHHHHHHHHH" does get old after an hour or two.



http://store.summitracing.com/egnsearch ... 857738+115

[Gavin]

Where is the best place to apply dynamat - on the floor, on the firewall?

[Bugfuel]

All large areas of sheetmetal that could vibrate or flex. It is more or less useless in corners or on support beams etc. that are already rigid by nature. It works as vibration noise dampener, not so much as a reflection noise stopper. For example, you need large patches on the inside of the doors and roof, and quarter panels. But the patch does not need to reach all the way into every corner or edges. It adds weight to the panel, preventing it from vibrating and flexing.

It is amazing what a 60% coverage did for my 66 bus doors... they close with no rattles, like a modern new car door. Thump-click. No other mods!


All wide sheetmertal surfaces are like speakers, or sound amplifiers. Deactivating those is your main goal.

Jan

[slowe30]

FYI: instead of dynamat, you can use "peal and seal" or some other kind of asphault roof patch from home depot/lowes for $10 instead of about $100. it's self adhesive, black/tar-like on one side, silver on the other side.... i used it in my ghia doors, under roof, under front hood, etc, much to my satisfaction.

[Towel Rail]

Lots of good suggestions here. I'll add:

1) oilbath aircleaners seem to quiet the intake better than paper/gauze filters
2) balancing all the internal components could make it "smoother" if not quieter
3) dropping the idle as low as possible/practical
4) rubber engine mounts don't send as much of the vibration through the body as urethane mounts

- Scott

[Marc]

...i found here in this site that longer rods makes the engine overall sound quiter...
http://www.popularhotrodding.com/tech/0 ... amper.html...

While that might be true in some cases, it wouldn't be helpful on a stock VW engine. With a stock 5.394" rod and 69mm stroke, the VW has a rod ratio of nearly 2:1 (most V8 builders would give up a nut for that, they're usually dealing with too-low rod ratios) and that's approaching the maximum practical ratio for a street engine. Longer rods cause the piston travel to slow approaching and departing TDC, giving the piston time to "flutter" under light loads.
I once had a race engine with a 2.1:1 rod ratio...it was great at high RPM, but below ~1500 it rattled like a diesel.