Cylinder Heads 101

moper said
I agree with all of the theory BJR, but numbers need to be taken with a grain of salt. I would caution the use of exact figures in any dyno room, or flowbench. Thoose are simply tools. I can make almost any number I need appear on a flow bench, that doesnt make it accurate. This is not an attack on you, just an observation. Your results depend on your equipment, your location, and your methods. The only way to get accurate readings on more than one head, is to have the same guy, in the same place, on the same bench, do them back to back, recalibrating after every head. I dont take any numbers as exacts..You can only use them as an indicator orf a trend, nothing more. Dynos can be way off too, again depending on the situation. Also, using an alcohol engine as an example is at least in my opinion a little deceptive too..lol. Impressive, but deceptive to a new guy. Just some more random thoughts from me anyway....

Moper, I'm the only one that flows heads at my shop and I do all the porting. So the methods are the same and the bench operator is the same and have spent days back to back to back flowing heads. As you say you can get and achieve most any #s on a flow bench or dyno and this doesn't mean that its accurate, I agree. But I've cross check my work on my bench with the bench at Barnett Performance, Zeeker Performance, Engine Systems and others and the #s are +/- 5 cfms, so I would say that they are fairly accurate.
Also the dyno #s that I come up with here are usually seen at the track also in the ET slip, so I have to say that this must be accurate also.
I've been building and flowing and dynoing engines for 20+ years so I have a good data base to fall back on, and trust my figures are accurate.

BJR Racing