Measuring head flow

Does this require specialist machinery? I would guess so, but not entirely sure...

like a flow bench?

Flusted wrote:like a flow bench?

Ah right, maybe. Just wondered if it could be calculated using mathematics?

maybe with liquid? im clueless when it comes to this sort of thing

Flusted wrote:maybe with liquid? im clueless when it comes to this sort of thing

Me too mate

I suppose you could measure the volume of the port using liquid, but that wouldn't account for any turbulence in the flow or obstructions, i.e. valve stems, guides etc

[You must be registered and logged in to see this link.]

cool.

dirtytorque wrote:[You must be registered and logged in to see this link.]

cool.

Aaaaaahhhhhh! That answers my question...not sure I would want to spend $997 on a flow tester...

mrbeige wrote:

dirtytorque wrote:[You must be registered and logged in to see this link.]

cool.

Aaaaaahhhhhh! That answers my question...not sure I would want to spend $997 on a flow tester...

Its specialist stuff .
We can't do everything at home in our garages mate.

dirtytorque wrote:Its specialist stuff .
We can't do everything at home in our garages mate.

Yeah, but don't you wish we could

didnt think much of his "g" clamp style head bolts

If you need any heads flowing I have an inhouse bench fully digitally calibrated. Runs on 8 vacuum motors so far I've had to rebuild it once and burned out 5 motors. Total cost to date stands in just under 2.5K with all the adapters for different heads.

It works on pressure differential between a known orifice and your head.

If one wants to really know how it works I'll explain one day when i got a bit more time on my hands

Pretty pictures of a recent test I did on the SEM intake manifold for the Vortex forum.

[You must be registered and logged in to see this image.]

Cooool! It'd be interesting to understand how it works

What sort of cost is involved with flowing a head, and when you flow the head, would you 'fix' any discrepancies between the different ports?

Normally when I get my hands on a ported head I tell people to sell them as it is easier to start again then to try and fix problems.

On average it takes an hr per port once set up on the bench to measure flow and airspeed. Realistically because it is so time consuming the flowbench is used for R&D work to see how different changes effect flow. The end result being that someone can tell you how they want their head to perform and camspec and you can dive in headstrong knowing what you are doing will work.

Next you'll copy it across all 4 ports or more depending on engine using maths and engineering. On average so long the ports mathematically match you will be within 3-4% variance between them which is considered an acceptable variable, so you then only flow one cylinder to pull figures for the head.

For example simple R&D work has shown that correct bowl throat and valve work on a 16v head can get you upto 15% gains on intake flow before you even start to port the intake. Whereas porting without the afforementioned can only gain you upto 8-10% depending on casting. And in the case of 1 company no gain instead a 5% loss during the peak lift range of the cam. Which they can give you for £750+

Excuse my ignorance, but what is the bowl throat? Is that the section of the port behind the valve?

Dont worry some terminology for you

mouth of the port is the opening to the mani
bowl is the area under the seat
floor of the port is the bit that faces the block
roof of a port is where the guide protrudes from
throat is the restriction through the valve seat
SSR - short side radius is the curve from the floor of the port into the seat

JNLRacing wrote:Dont worry some terminology for you

mouth of the port is the opening to the mani
bowl is the area under the seat
floor of the port is the bit that faces the block
roof of a port is where the guide protrudes from
throat is the restriction through the valve seat
SSR - short side radius is the curve from the floor of the port into the seat

Sweet, cheers dude

JNLRacing wrote:Normally when I get my hands on a ported head I tell people to sell them as it is easier to start again then to try and fix problems.

On average it takes an hr per port once set up on the bench to measure flow and airspeed. Realistically because it is so time consuming the flowbench is used for R&D work to see how different changes effect flow. The end result being that someone can tell you how they want their head to perform and camspec and you can dive in headstrong knowing what you are doing will work.

Next you'll copy it across all 4 ports or more depending on engine using maths and engineering. On average so long the ports mathematically match you will be within 3-4% variance between them which is considered an acceptable variable, so you then only flow one cylinder to pull figures for the head.

For example simple R&D work has shown that correct bowl throat and valve work on a 16v head can get you upto 15% gains on intake flow before you even start to port the intake. Whereas porting without the afforementioned can only gain you upto 8-10% depending on casting. And in the case of 1 company no gain instead a 5% loss during the peak lift range of the cam. Which they can give you for £750+

Have you had any experience of CNC heads! Especially interested in your opinion of the big valve CNC G60 head. Obviously they flow lots of air and you'll get maximum HP and Torque but my concern is air speed and swirl reducing part throttle response and drivability. Are my concerns unfounded due to the fact it's a supercharged engine? They also show the same flow chart graph for the 8v NA head!!??

[You must be registered and logged in to see this image.]

email me on jnlracing @ googlemail.com and I'll forward you the real results of that head vs standard vs mine vs a eurospecsport one. Lets just say they are a bit keen on their numbers

[mod edit]Spaced your email, to stop spammers Beigy

lol cheers

Glad your thoughts are what they are on the head, same as i heard.

I have heard dubious things about the quality of the finish too, things like over spray on the cam caps etc.

What you really want is an old man in a shed. Probably.....


I have a head for my VR from a VW cup car apparently ported and polished nicely, and I'd love to know how it will perform, the ports are much larger, with smaller guides but standard valves. Need to get it lightly skimmed (hopefully there is enough meat on it) and valves and springs put in. The exhaust ports do need a repolish I would imagine.