Intake Design Paper

[Sam Zimmerman]

Hey guys,

I am giving a presentation for a combustion institute conference and have a rough draft of a paper for their proceedings. I am only allowed 6 pages so I can't fit everything but would appreciate feedback on the paper. I have never seen a post like this before here but what the hell. Let me know anything you disagree with.

Paper is here

[Mike Claffey]

Howdy, had a quick glance through,

just after the intro

"How his engine power output influenced by the location of resonances and anti-resonances across the speed range?"

Should this read "How is engine power..."?

Regards

Mike

UWA Motorsport
www.motorsport.uwa.edu.au

[Chris Boyden]

Great job with the paper. The only thing more that I would like to see is stuff that you are still working on....like changes in cross sectional area from runner to plenum, restrictor to plenum and how that affects impedance and torque, etc.

When we did our flow testing, I found pretty interesting that the restrictor flowed 7 to 10 cfm more air @28" h2o by itself than bolted to the plenum w/ runners due to expansion and the cross sectional area change. However, this
is a far cry from the work you guys have done.

good luck with the presentation.

"How his engine power output influenced"
probably already caught this little mistake...but here it is anyway

[nathan s]

Sounds like money to me. I don't think you could really add much without making the paper hard to follow.

One thing I did notice is that you didn't mention what wave number you were using for your different runners. If I am not mistaken, your impedence is effected by how far your wave has gone through the pipe.

Otherwise, it looks good. Good luck with the presentation.

BTW...Is there any chance I could score a copy of notes from that conference? It sounds interesting.

[jonnycowboy]

Hi,
your paper looks great and also looks to be a new future reference for teams looking to tune their intakes!!
I'm currently designing the intake for the concordia car, also a cbr600f4i.
I used another formula:
RUnner length=(((720-CAMDURATION)*0.25*2550)/(RPM*ReflectiveValue))-(0.5*DIA)
where reflective value is either 1st (strongest, 2nd or 3rd.
I decided to go for 1st wave reflective which gives me a length of 28 inches, which is fine (we have the room). However I don't see how you could calculate the runner length from the impedance formulas you gave, perhaps if you could explain this a bit better here it might be more clear for us mathematical weaklings!
thanks!
-Jon

[Sam Zimmerman]

There is not a calculation per se for runner length in my paper, but an interpretation of the graphs produced. The example shown in the paper shows that where the two strongest resonances occurred were also where the two torque peaks occur. The resonances are the local minimums on the impedance vs. engine speed graphs. The downside to this method is that it involves interpretation rather than a direct calculation. The good part is that it takes the entire system into account and the entire engine speed range.

If I were designing an intake for a diesel generator that would only run at a single speed, other methods are far simpler. My argument is that for an engine that redlines at 12K or more, the simpler methods may get you in trouble by causing large anti-resonances at undesirable engine speeds (i.e. the torque curve shown in the paper).

Having said all that, your method jonny is a more precise variation of the Platner method shown in the paper, which worked great for Chrysler with their high performance intakes. I am just trying to find a solution that will offer a better torque curve prediction for high revving engines such as ours.

If I had time, this method could also be used to predict the phase angles in the pressure waves so one could precisely match the valve timing with the pressure waves in the intake and exhaust but that will have to be left for someone else's master's thesis.

[John Bucknell]

Good job Sam.

The multiple resonances is something which not many people catch on to, and you show directly that it is there and has many peaks. Hopefully everyone who needs a quick education on manifolding takes a look at this.

[B Lewis @ PE Engine Management]

Hi Sam,

The paper does a good job of describing the manifold as a system including the subject of anti-resonance (which very often is completely overlooked). We have quite a few SAE teams ask us for information on manifold design throughout the year. Would you mind if I reference your paper in the future?

[Sam Zimmerman]

I don't mind Brian, but I would rather you wait for the final version in about a month or so.

[B Lewis @ PE Engine Management]

Thanks Sam, I will wait. Will you post a new link when you are finished?