drilling out mufflers

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Darrin lawler
Posts: 93
Joined: Tue Apr 09, 2002 12:02 am

drilling out mufflers

Post by Darrin lawler »

Does drilling out the mufflers on the la15 and 25 really help. I have some I have drilled out and some not. I really don't notice a difference.
Darrin
wing nut
Posts: 118
Joined: Sat Dec 29, 2001 10:24 am
Location: USA

Post by wing nut »

Hi Darrin, I've drilled out the stingers on the 15's I use and noticed a considerable gain in RPM, sometimes as much as 1500 RPM. I've never bothered to drill out the 25's. For limited B, RPM's don't really seem to be much of an issue.
wing nut
Posts: 118
Joined: Sat Dec 29, 2001 10:24 am
Location: USA

Post by wing nut »

Oops, just remembered that I have drilled out 25 size mufflers. I started using GWS mufflers as a replacement on my Irvines. The GWS is much cheaper, $7 vs. $26 for original equipment. However, the stinger diameter is much smaller on the GWS, so I've been drilling them out.
Hat Trick
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Post by Hat Trick »

Drilling the stingers is usually good for 500 to 1000 RPM in my experience! Remove the baffle also or hog it out a lot as well.

On the bladder system I've found a venturi to be good for 500 to 1000 also.
jj
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Post by jj »

You should take the application into account.

For SSC (LA15 ..) you can get some performance but are limited in rpms so you may be at the rpm limit anyway without the need for much modification. I've found it to be a pain to need to carry 5% nitro fuel to keep the engine from going over the rpm limit.

While I'm not very well versed on Lim B, as I recall you are supposed to use a stock muffler. That would make modifying it somewhat questionable. If you are flying a limited class it just doesn't make much sense to allow mods.

For Open B you can certainly gain more opwer by opening up the muffer; however I'd suggest either using a Macs muffer (good for about 500-800 rmp, or a mousse can muffler which is good for 1,200-1,500 rpms, possibly even more. Muffler mods are permitted for an Open class.
Darrin lawler
Posts: 93
Joined: Tue Apr 09, 2002 12:02 am

Post by Darrin lawler »

I thought that you coundn't alter the muffler. No wonder my scores were so low last year.[:o)]
Hat Trick
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Post by Hat Trick »

Drilling out the stinger and removing the baffle is allowed in LIM B just like in SSC. Lim B also has a prop and RPM restriction like SSC.
EK
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Location: Aubrey,Texas

Post by EK »

Baffle in or baffle out, I have not seen any difference. A motor that won't make rpm either needs more time or has been run hot and damaged. A new piston and sleeve will fix the damage unless the bushings are also gone. You'll know the bushings are gone if more fuel comes out the crank than goes through the carb and 4 oz isn't enough to make it 5 minutes but she runs like a scalded ape.
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