Chris White

Videos of flow bench testing the cylinder head for the track car….
Not a lot of ‘action’ but it is fun to see some of the numbers!

The flow bench is a computer controlled set up – you program the valve openings you want tested and it will actuate the valve, wait for the flow to stabilize and then it records the flow and moves on to the next step. I measure every .050” of lift….it takes a while!

I had to 'whip up' the aluminum bridge that keeps both valves opengien at the same lift.

http://www.youtube.com/watch?v=SKegh5nRi-o

http://www.youtube.com/watch?v=sHT7YJdYOlI

fast951

Where is the velocity strobe and the swirl meter?

Chris White

That's too old school. I put little Hampsters with radios inside the combustion chamber. They radio back the info. Its kind of a pain to make them wear their goggles...I don't want OSHA bugging me.

gcb951

How much you want for the used hampsters?

eniac

Just don't let the ASPCA find out that you shaved the Hampsters first for less air interference.

Chris White

Sorry, they joined the local union - I am not allowed to sell 'em.

JET951

thats cool, i want one of those machines. i have never used one Chris, does it flow backwards? as in combustion back out through the inlet?

JDS968

Some day I really really really want to get one of these and then start grinding my own camshafts...

A.Wayne

Chris is that 330 cfm @ .455 lift , what mercury value ? i couldn't read the tube on the side...

Chris White

28" on that test (the 'depression' is also programmable) - it was also quite warm , the correct flow was 335.3cfm @ .455. I ran a test at 25" later to see the difference - noticble but not very significant.

Chris White

A couple old 'old school' cam grinders on site - When I get some time I need to source some 16v blanks and grind up some new cams made for turbos....

Chris White

If you look at the video you can see a large black switch behind the head – that reverses the flow so you can measure exhaust flow. (260.5cfm @.4486”).

The computerize system is really pretty slick – it makes the tests very repeatable. The blue ‘support’ under the head has interchangeable diameter cylinders so you are testing the head in a cylinder similar to the engine block to take any valve shrouding into account.

gt37vgt

for repeatable comparative flow testing all you need is 2 vacuum cleaners some clear tube and a hole in the bench . its the ten cylinder heads you destroy figuring out what works thats expensive .

333pg333

Nice stuff to watch. Do you have numbers for a stock 8v head Chris?

Chris White

Yes and no. It is repeatable for work being tested in the same session aback to back. Temp and air density can have a significant effect. For example – after an afternoon of craning way on the flow bench I had raised the test temps to 120 degrees (you are measuring the temp of the air ‘inside’ the flow bench since that is where you are measuring the flow). The correction factor was over 20cfm at high flow rates. If you are doing an immediate back to back it doesn’t matter – but if you are doing a before and after measurement of mods it does matter.
Some other tidbits –
Flow volume does not tell you velocity
Pressure drop does not tell you volume or velocity
Nothing tells you swirl except a swirl testing device
The ‘hole’ in the bench is fairly critical - it needs to be a decent length to get the air flow undisturbed. It needs to be the same diameter as the engine cylinder to mimic the flow at the valve head.

All that being said – you can measure improvements with a fairly basic set up.
And yes, if you really want to figure out head flow you will trash a lot of cylinder heads! Even the best head guys cannot tell you exactly what you need to do without trying and most will not even make a comment on work without testing it. If I look at a head I can tell you if the head work is bad – but I would have to flow it to tell you if it is really good.