Compression ratio tester

[bill gillespie]

Guys,

Can any of you explain to me exactly how a " whistler " measures compression ratio, and what engine prep is required ?

Many thanks,
Bill

[Jon Jeffords]

Bill, the way it was explained to me, the Katech whistler is basically an acoustic measuring device that functions much like when you blow air over the top of a beer bottle.

Oversimplified, as the whistler blows air over the the spark plug hole while the piston is at TDC, it measures the resulting natural frequency of the air volume resonating in the combustion chamber. Knowing the air temperature, the Whistler calculates combustion chamber volume at TDC. Knowing the engine's displacement (bore & stroke) and number of cylinders, the Whistler can then calculate compression ratio.

Google "katech whistler" for hours of reading entertainment.

[DB4 Tim]

Does it require a very quiet back ground so to speak....the only item is does not call out is the background prep

All you need is a low volume air source and a 120V AC supply
• Works with 4, 6, or 8 cylinder engines
• Cubic inches from 6 to 600
• Engine temperature range 30 to 200 deg f Included with the WHISTLER:
• FN, BN, BL, J and 18mm spark plug adapters (12mm motorcycle available)
• Verification bottle (allows you to check the accuracy of the unit at any time)
• Easy to understand instruction sheet

[Jnovak]

The whistler actually works. NASCAR has used them for years & when engines have been torn down the displacements & compression ratios were very close to actual measured results.

Thanks ... Jay Novak