A freind of mine built a dyno for model race
boat engines and installed it in his garage.
1/ Build a floor mount with rubber isolators to avoid vibration transmission
2/ Insulate the floor
3/ Bulid a box - better if one outside wall of the garage is used.
4/ Insulate the box
5/ Provide a snorkel intake that runs through the garage wall, has a fan and is insulated as well. It is best if the mouth of the snorkel is above head
6/ Provide an exhaust
snorkel that runs through the garage wall, is insulated and runs up the outside of the garage to roof height. Note this would be pipe in pipe. There would be a snorkel duct to exhaust the cooling
air and the engine
exhaust pipe also runs in this duct. There may be some argument and complexity in running the exhaust this far but it will result in the quietest install.
FWIW - These race
boat engines put out about 8+ hp and scream at 28,000+ rpm
. They are noisy little beasts. He imbeded a plexi viewing screen
in his box but it was nice and quiet both inside and outside the garage.
These little beauties will do over 95mph on the water