PTS Flowbench Forum

Tony wrote:

S2Z wrote:
S2Z response:
There is a direct correlation between HP & CFM.

There is certainly a trend between air consumption and power.
But not a direct correlation.

Over scavenging, incomplete combustion, wrong mixture, wrong valve or ignition timing can all cause a dramatic power loss, but you claim there is a DIRECT correlation of power to air consumption.

If that were true, engine tuners have been completely wasting their time.

Actually there is a direct correlation Tony.
You choke a head with a limited amount of CFM or bad port design and it won't matter what cam timing events, scavenging,ignition timing , carb etc you have, it will be a dog.
ALL good engine tuners look at a cylinder heads potential to help determine what the maximum feasible output for an engine may be. Then Cam timing events are applied to optimize that head and it's power potential on that engine.

AceR wrote:[
ALL good engine tuners look at a cylinder heads potential to help determine what the maximum feasible output for an engine may be. .

That is certainly true.
But there is no guarantee that every single engine will always achieve that potential.

You can adjust an engine so it runs so lean it misfires, there is no way that the power is always directly tied to airflow. Or to fuel flow for that matter.

Tony wrote:

AceR wrote:[
ALL good engine tuners look at a cylinder heads potential to help determine what the maximum feasible output for an engine may be. .

That is certainly true.
But there is no guarantee that every single engine will always achieve that potential.

But that is not the cylinder heads fault.. It will make the power... if you let.

AceR wrote: But that is not the cylinder heads fault.. It will make the power... if you let.

You cannot get power from just a cylinder head, you need a whole entire running engine.

You have to map out any performance engine before you even lay a spanner on it.
No point having an excellent head if you can't take advantage of it.

Hello, I have recently aquired an Arduino and while I was searching for flow bench applications I came across this thread.

I just thought it would be good to interject some to this thread.

First, a MAF measures air mass, not airflow volume. I'm sure you could extrapolate that from the data but I thought it would be a point to consider.

Also the graph shown on the first page of this thread is not an accurate representation of the voltage output of a MAF.

The output is actually logarithimic. so the more airflow at higher regions returns an ever-decreasing voltage increase. this makes the resolution worse as airflow increases.

I was thinking along the lines of using a pressure transducer and the arduino on a orifice type bench.

Just my 2 cents

Victor

Hello Victor, welcome to the Forum.

Yes, MAF's measure mass air flow, and the non linearity is actually an advantage in an engine application, but a huge obstacle to overcome in calibration if you want an exact air flow measurement readout.

The consensus here, after a great many years of flow benching is that a ratiometric pressure measurement between what you are testing, and a known flow orifice is definitely the way to go.
It effectively removes all the variables associated with air quality at the time of measurement, and no corrections are necessary.

Forum members have developed some flow bench electronics, and some very professional software to go with it, at a very friendly price that may be of interest to you.

If your interest lies more in tinkering with the electronic and software side yourself, than building the actual bench, then it should be a very interesting and rewarding learning exercise.

Whichever way you wish to go, there are many Forum members here that will be very happy to help, you have certainly come to the right place.

Hi Tony, thanks for the welcome.

I've been a member of the "old" forum before. I built a simple orifice style bench with the help of info provided by members of the board.

The pictures went away with my old ISP, but here's one of my old threads;
http://www.tractorsport.com/forum/viewt ... ?f=9&t=905

And you hit the nail on the head, a tinkerer I am. I've recently started working with microcontrollers and can envision a seemingly infinite array of possible uses. One of which is my flowbench.

I'm sure you'll be seeing posts from me in the coming months.

Victor

ps. sorry for the hijack.....

Victor,
If you twist Bruce's arm, he might supply you with a bare Digital Manometer circuit board.
That has three differential pressure measurement channels, with three analog outputs that would hook straight up to your Arduino board.
It would save you all the trouble of going through the rat's nest prototype stage, and you could jump straight into the software.

But that would take all the fun out of it! And I'm not pressed by any schedule.

I'm hoping to be able to proceed through all of those details, But I'll keep that in mind in case I find myself mired in some never ending project.

Thanks
Victor