Exhaust whistle
 

I was in Brainerd at the national event and noticed a lot of the cars had a whistle at idle. Almost sounded like an old VW bug. Just yesterday my buddy fired up his 598 for me and the wistle was really loud at idle. Has anyone els noticed this? If so, do you know the cause? :?:

Lots of cubic inches,and the compression of a Big block chevy,that is the most awesome sound! sounds kinda like a cricket

My buddies 598 is a 10.5-1 motor that runs on pump gas. I'm not sure if compression is the cause. One of the theory's he had is its the D shaped exhaust ports creating a negative pressure or something at the header as the exhaust flow exits the head and enters the header. Personaly I don't care for the whistling sound, and would like to avoid it when I build my headers.

I started a very long thread about this on SpeedTalk.; Many different of the top engine and cylinder head professionals in the industry chimmed in about this subject. People heavily involved in Pro Stock racing posted.

Bottom line is that no one really knows.

10 identical pro stock engines. all engines had equal power to within a few hundreths of a second with each other in the same car. 5 identical sets of headers. Engines that had the Chirp/Whistle/TGweety Bird, Lost it by changing headers. Engines receiving the headers that were Chirping on other engines that did not chirp before still did not chirp when receiving the headeres that chirped on the chirping engines. Engines that chirped quite chirping with head chenaces.

Brad and David Morgan and their creww spent much time in R&D just to pin point what was causing the strange sounds. Notta!. No conclusions.

So I guess we will all keep guessing indefinetly.

Ed

could it be a slight gasket mismatch causing exposed gasket to vibrate?

I guess i'll just build my headers and hope for the best. It sounds like its a combination of cylinder head and header design. With the right combination you get the chirping. Or in my case it would be the wrong combination.

Alot ofthe big cubic inch BBC engines here where I race justy about all have the chirping noise,and they are all big cubic inch motors,I personally like the sound,But it will never be better than the surging of my blown Small Block,and the awesome loud ear piercing burnouts from a blown alcohol motor

I thaught about building a blower or turbo motor, and i may still do that if i can afford it. Personally i prefer the sound of a well tuned naturally asperated big block.

My favorite sound is the roots blown alcohol cars backing up after a burnout.

Ed