Animated Porsche MFI engine is here!

[DarrylD]

Ok, I took a stab at how the injectors would be timed on the MFI system. Any and all feedback on the correct sequencing is gladly accepted... here's a first shot at it:



Thanks for indulging me!

[rexav8r]

I just want to point out that it's a SICK man that has the ability to crank something like that out in his "spare time" !!!

I owe ya a beer just cuz it's THAT cool !!!!


Thanks!


(I've got the '70 MFI by the way )

[Jim Richards]

Darryl, that is fantastic!

[silverc4s]

Darryl.

Thank You.

I have always wanted to see this engine in action, and you have made that possible.

What is the small fuel spray above the butterflys? i am unanware of it's existence. That is what makes these efforts so enjoyable..
Thanks again...

[poorsha]

Way too much free time.
Government employee?

Great job.

[Tyson Schmidt]

Where's the oil smoke on start-up?

[Early_S_Man]

Awesome, Darryl! The injector timing looks fine. I named my saved version 911-83mfi.gif!!!

Bill, those are the cold-start injectors above the throttles on the 'plastic stacks' of '72 - '76 MFI production engines!

[Jim Richards]

Originally posted by Tyson Schmidt
Where's the oil smoke on start-up?

You ARE evil, Tyson!

[304065]

Darryl, you might add a toothed belt drive running off the forward part of the left camshaft, and some motion on the pump itself. . . although the pulley is on the other side. . . maybe just the belt, running at an angle, driving the pump?

[silverc4s]

Thanks Warren. That was the only thing I could think of, but I have never seen the later system up close & personal. Always assumed they were up higher, based on the early air cleaner design..

Darryl,
Maybe those cold start injectors should only pulse once in a great while - to more accurately depict their purpose. I am not a software typw, so I have NO CLUE whether that is possible or no...

[jpnovak]

Fantastic! Now it just needs to be set at WOT.

[Shuie]

Spectacular!

Thanks Darryl

[Quicksilver]

I still want some flame going out the exhaust.

Wayne

[DarrylD]

I've got a few tweeks to make to this but it looks like the MFI pulsing is OK with you guys. I thought it would be a bigger and more dense spray of fuel than the constant fine mist of the CIS, since it's such a short period prior to the intake valve opening.

I'll play with those cold start injectors, that looks wrong to me too.

Ok, now I'll start playing with modeling the intake, compression, detonation and exhaust strokes.

Oh, "government employee" very funny. I'm a retired software engineer from a little PC software company in Redmond, WA... or at least it was little when I worked there...

[svandamme]

looks sweet , just one thing : the cis model has domed cyllinders, while the mfi has flat ones ( at least compared to the cis )

in reality , the CIS are usually the flat ones, and MFI ones have more of a dome ( at least the S models have , don't know about E's or T's )


how do you edit these things ? not animation shop i hope? frame by frame?? or is there some gizmo that makes the tedious frame by frame thing easier??

[DarrylD]

Hey Stijn!

What you see is right out of the Porsche technical manual. The CIS animation's pistons are very domed, to the point of almost touching the intake valves @ TDC. The MFI ones in my model are slightly domed, notice the series of engine is 911/70, that's a 1971 factory race engine, slightly higher compression than a stock version (you buying that? It's my story and I'm sticking with it).

Ok, animating this stuff is low-tech, high tedium and maybe there is a package that could automate the process to a degree but what fun would that be? The tools I use are an HP scanner, Windows Paint, Microsoft Picture-It 9.0 (to do rotations) and GIF Construction Set Professional (to build the .GIF file from 20 .BMP files and "super compress" the result). Windows Paint is a very basic but powerful editing tool, like an acetylene torch, some people can do amazing things with it and others can make scrap metal or need to be rushed to the emergency room.

This is mostly cutting and pasting pieces of the original cut-away drawing scan to isolate a component, say a pulley into its own file. Edit the file, fill all the pixels around the "pulley" with transparent ones in their place. It's important to save the files as .BMP file type so no compression takes place that loses crispness of the image (such as with a .JPG file) Pull the image of the isolated piece into a graphics program that allows you to rotate it. Divide 360° by the number of frames in the series, 20 frames to model a 4-stroke engine is 10 frames for each revolution of the crank, so a 36° increment per frame. Make 10 versions of the "crank" file, each one +36° rotation from the previous. Cut and paste the "pulley" back over the pulley in the original scan, save each version of that file 10 times... now do this for the cam, rods, cooling fan, etc. etc. etc. Fix any "blemishes" using 6x magnificatin to edit at the pixel level.

I also calculate the pixel positions of a piston or rod by using the trusty old Pythagorean Theorem, a˛ + b˛ = c˛. That's what insures the smooth transition between frames.

The trick is to look at the drawing and sequence your work so things can be placed into re-usable subsets, like the valve train, then model it, flip it over to work on the other side and add the unique cams afterwards. It really is like knitting, you just focus on the "row" you're working on and look up and see a sweater at some point.

So, are you sorry you asked?

[jluetjen]

That is AWESOME. The only thing that is missing is some overlap with the valves. It looks like it has CIS cams in it with no overlap. In reality the S cams have overlap for about 60 degrees of crank travel as opposed to the CIS engines where the valve events are almost serial.

[DarrylD]

Yeah John, I had to simplify the valve lash to fit in the limited number of frames. I was happy to get the cams to have a similar offset with the approach I used to model the movement of the valves. Now if I had used 40 frames instead of just 20... I'd be,
COO-COO FOR COCO-PUFFS! COO-COO FOR COCO-PUFFS! COO-COO FOR COCO-PUFFS!

[Grady Clay]

Wonderful job!

Let’s also work on the cam profile. Perhaps “S” cams on the MFI engine?

I agree it should be easy to animate the oil pump shafts with just a line from the center to the periphery of each shaft.

I like the idea of animating the MFI pump drive belt. How about two MFI pump pistons?

How many images per two revolutions?

I can’t wait to see the animation of the intake, Otto cycle in the combustion chamber, and the exhaust – complete with the cold start and smoke on start-up. Perhaps the color can reflect the temperature-pressure.

Is it possible to have “overlays” that can install to show the chains, sprockets, jack shaft, and tensioners?

I think I see where this is going with sound, cranking, start-up, and revving to redline. Idle as a screensaver, starts and revs when you move the mouse or boot up.

Cool stuff.

Best,
Grady

[DarrylD]

Easy Grady, I'm not sure if brain aneurysms are covered by my HMO!