Head Porting- Milling (CNC)

[Dodo Bizar]

I might have figured Motoman out ... he does the right thing for the wrong reason. Neh I am exaggeration.

I did some math on it and indeed, when CFM stays approximately the same but speeds are higher, yes energy content of that piece of flow is higher compared to 'normal' situation. When the inlet valve is closing it is harder to stop the flow in motion which will lead to more leakage into the combustion chambe3r before the valve is closed. Which is good, more air and fuel can get in that way.

But... I think there is another effect completely untouched in Motoman's powernews. It's the pulsation timing which changed as well. He pays little attention to the blending of the normal intake port towards the 'throat' part. But there lies the key perhaps. He simply is tapering the intake port! In a demonstration video of Dynomation 5:

http://www.worlddragracing.com/download ... _F_800.mp4

They even explain with an example that tapering the intake port from 2 to 4 deg can shift the powerband by 500 rpm! It's because the higher velocity changes the speed of the sound waves scattering through the port. A wave which runs out and in the intake port takes longer when the taper and therefore velocity are bigger under the same CFM. This might actually be the main reason why motoman's ports can work pretty good. Still you need a bit of luck perhaps.

[Dodo Bizar]

Check the video from 25:20 to 26:00 for the part I am referring to.

Anyone familiar with this Dynomation package?

[mynameisowen]

Interesting

[Dodo Bizar]

I actually started work on a 10 day demo version of Engine Analyzer Pro V3.9... today second day. I try to rebuild the B16B setup I own and first results are promising, not good, but promising. If I get results to my liking I'll also try to cover the D14 setup of myself this weekend.

I should open another thread on this subject I believe. Wasn't there already a thread with such a subject somewhere? Owen perhaps?

[mynameisowen]

Don't remember making or seeing one about that program

[Dodo Bizar]

Darn I've done little... I only got the B16B worked out.

I was really amazed by simply putting head flow coefficients, cam profile specs (open, close, duration, height) and from the top of my head putting inlet and exhaust dimensions I got the shape of the dyno graph pretty much right. In absolute sense the prediction was very low at first (20% missed), but most of it was covered by tuning in the internal friction losses of the model. That brought me really close to the actual results.

I have an issue with ignition mapping. You got 3 options, default is to let the software guess best performance point... which leads to an high knock index, so in reality you would suffer from detonation and because of that, even when excepting the detonation you don't make maximum power that way. The other options are based on a ignition timing table you give in yourself. Well, lucky me, I just asked my friend CRX2 for the actual tables in my setup. Turned out the actual ignition point is way later than the prediction from the software was. We talk about 25 deg BTDC in the VTEC zone instead of 35.... now there are two options. Either you specify the software to calculate with it's normal burning rate and get the performance from that. That leads to less power and less of a knock index. But the other option is the reversed... you specify this is producing maximum power and software assumes your mixture burnes more rapidly than it's own prediction which leads to higher power and higher chance of knock... in my case a value of 4 appeared were 1 means chance of detonation and 2 means detonates for sure. Since I have removed the head in the meantime I know it has zero detonation spots... bottomline, weak point of the software and I opted for option 2, give ignition table myself and use normal burning speed. It can not find max power the same way a real dyno does. In a real dyno power is killed before detonation starts usually... exceptions do exist, especially with high CR cars, but Lakai with a CR of 10.3 was one these exceptions. His car detonated before max power was reached and I think it was only 1 out of 50 engines I assisted over the past years.

But... using this tool I hoped to find some smart ways to get more power from the B16B. The short answer is no, Honda really went to lengths getting the most out of the engine, there is an actual reason it's hard to get 100 bhp/litre... let alone 120+. I had a few things in my head for years... most of them didn't work as I hoped, I just had it wrong. There are options to get more power, but very limited and often with great sacrifices. Changing the cam timing can bring me some more power, but often at the loss of mid range power... with the loss bigger than the gain.

There is still hope for me to find something hidden in the B16B though. The tool does not cover exhaust manifolds properly. Reading between the lines you see it's even for the developers still not crystal how to get it right. Biggest sign on the wall to me is that there is no basic layout given for the manifolds. A short 4-1 mani is given the same way as a normal 4-2-1 mani. A long 4-1 mani or in my case tri-y (which is a long 4-2 and short 2-1 section) is only identified by a longer first runner... there is no such thing as a second runner, except steps can be indicated. Firing order, closely related to this subject, is neglected.

Let's say on average the tool under predicts by 5 to 10% but some basic trends can be studied really well. I studied intake runner length changes (up to enormous lengths, and guess what, the stock is the best.......), studied cam timing changing and a lot of component changes. Hint: B16B pistons are not coated on the top side! Only on the skirts. For good reason and the tool did find it. But I miss a bit of faith in the exhaust mani department, especially since I see exhaust velocities flying over the speed of sound, even if I correct for exhaust temp and pressure locally. But I have the feeling there are more tools failing once you get supersonic in the exhaust, which I believe might be the key of B-series engines to start with and the reason small tubes work better than big tubes sometimes.

[Dodo Bizar]

http://www.dodo-upgrades.nl/improvement_guess.bmp

Link since picture is oversized for this forum.

Yellow is reality. Red my first guess (forget about the < 5000 rpm part, it's only VTEC cam actually which does behave like that indeed). And green the final guess I made being very close to reality. Only error in there is that I had put the ignition table and selected the 'this is how it burns' option giving incredible knock instead of 'let's burn realistically'.

[mynameisowen]

This program sounds pretty good, what's the interface of the program like? I have come across a program somewhat similar at uni called GT Power, has anyone heard of this?

I'm surprised and slightly relieved that you are finding it hard to get more power out of the B18B, after it is a Type R engine! I think it will also be quite difficult to get more power out of the exhaust without being able to manufacture your own exhausts.