You get pulses, both negative and positive, and depending on the cams profile, depends on how abrupt they are, and also there is a flow on effect, when the exhaust is open too, and the type of exhaust system also helps, as in scavaging the cylinder.
Since you have access to the NET, have a look at K-Jetronic fuel injection, you might learn something. Open your mind, and take it all in, get rid of your damn blinkers.

Well then you're both f**k.

Does it stream or pulse?!?!
so what you're saying is, that solenoid closes & opens according to throttle positioning?
sounds familiar to what you'll use for stork standard boosted motors. usually mounted on the intake tube before the throttle body! old idea but affective against pre-ignition.

Yep, driving around in boilling kettles.....lol

whats your fetish with K-JET? you bring it up almost as much as you post photos of that damn ute.

No fettish, its just an eye opener for some. Ever had anything to do with it???

yeah i have had a bit.
not that it makes it relivent.

I used to work on a lot of European cars, Audi, Alfa Romeo, Pugeot, Citreon, Fiat, Lancia, Saab, VW, Volvo, Porshe, Mazerati, BMW, and Merc's, all have their peculiar/particular way of doing things.
When you look at it, they were way ahead of us in what we had here in the 60's & 70's, like fuel injection, 4 wheel disc brakes, and crash zones stuff.

great, so, as there is a direction change in the inlet charge. does that mean at some point the charge must have a velocity of zero?? therefore stationary and able to bond to nearby sufaces

mate, seriously, get over constant injection systems. or K-Jet as you must call it... since you honestly beleive in K-Jet, or shall we call it mechanical injection, what sort of high speed lambda data have you seen from an engine running constant injection??? im talking lambda logging at atleast 10hz???????

OK then, what is the evapouration temp of fuel??? A Porshe ( 911's ,etc ) from the 70's & 80's were using K-Jet. Are they not a performance car??? The thing is, when there is a change in direction, how long does it last, a few milliseconds.
The Japs have been using direct petrol injection for years. I worked at a dealership that had Mits, and in amongst the w/shop manuals were Direct Injected Petrol engines, 3.5lt V6. We never got it here, Why???
Why haven't Ford, or the other Oz manufacturers gone that way???
What happened to the Sarich ( spelling??) Orbital Engine???

petrol boils between 40-200c depending on pressure... and requiring roughly 900btu to transorm liquid to gas at 60f

after reading your response, im sure you are confused between DIRECT injection, and CONSTANT injection...

fact is, we ARE going for direct petrol injection, but direct petrol injection is a far cry from K-Jet mechanical injection that you like from the 70-80s..

you must be familar with the 70-80s 911 porsche CIS system because you refernced it in your last reply, so i ask, do you think that compares to direct injection??? and how???

fact of the matter is, that going away from constant injection and going to direct injection only strengthens my point about high speed lambda data logging... if you can understand the high speed lambda question, then you can figure what difference direct injection has to constant injection in regards to mixture ratio and ideal injection times

Ok, talking to my boss about this yesterday and its a big no no to polish inlets. Not so much for fuel sticking to the walls but how badly the boundary layer affects air speed.

For those that don't know about boundary layers I'll give you a 10 second intro. On a dead smooth surface with a fluid (gas or liquid) flowing over it there exists a boundary layer. At the surface the air is stationary but but as you get further away from the surface the air speed increases untill you get to a distance from the surface where the air speed is the free speed (the speed that it should be in a perfect world). The distance from the surface to that point is called the boundary layer.

Now in a set of heads with perfectly sized and shaped ports if you were dumb enough to polish your inlets then the boundary layer is up to 30mm thick off the surface. That would mean that you would need ports of at least 60mm in diameter before you get any air up to the target air speed. I don't know any inlet ports in a passenger engine that are over 60mm in diameter so you can see how badly you are killing your flow potential with polished ports. Fuel control is another issue altogether but it too is affected by boundary layer conditions.

The only time you would ever polish your inlets would be in the early stages of porting so its easier to see any small bumps or imperfections that you might have missed. Once you have smoothed them out then rip into your inlets again to roughen them up.

But as for polishing the rest then go for it, combustion chambers and piston crowns should be free of any sharp edges (especially around the valve reliefs, and domes of high comp engines) and polished to a mirror finish to promote good flame propagation as this prevents detonation.

As for the exhausts, again go for your life in terms of polishing if you want but a light polish will do as a light build up of carbon will occur no matter what over time.

It was briefly mentioned that polishing the chambers and the light carbon build up actually reduces combustion temps but that part all went over my head when it was explained to me.

cjh, The only reason why I think your polished ports might work is because they might be low speed, high port volume type heads such as 4V or seriously opened up 2V heads. I've seen a bit of port data as well as timeslips and the data don't s**t.

But what's with the K jetronic fettish? In its day it might have been the ducks guts because besides carbies there were no other alternatives but compared to what's on offer these days for a fraction of the cost it aint worth a pinch of s**t. Current generation carbies s**t all over Kjet injection. For a drag car its heyday was in the early to mid 90's but how many group 2 and 3 racers run mechanical injection today? Unless you can prove to me that it is better than what's on offer now then forget it. Build a competitive car drag car with a Kjet system and I might just believe you.

Well, I don't have figures, but I do see it at the tacho.
I had a headgasket let go on the ol 88EA. I needed the car going quick, as in, soon as possible.
I had a cyl head ready to install, it was one that I had polished, see pics, and now the acceleration is more crisp, revs out further, and I had to reprogram the piggy-back for idle mix, had to back it down 15% from factory.
I believe this head has improved the engine. The bottom end is original and untouched. Has std original cam too. Also now uses less fuel too.
I reckon I might need to up the fuel at the top end now.

My 2 cents.

 

 

Attachments:

My 88EA cyl head ported & polished. 002.jpg [ 406.48 KiB | Viewed 128 times ]

My 88EA cyl head ported & polished. 003.jpg [ 334.13 KiB | Viewed 123 times ]

My 88EA cyl head ported & polished. 004.jpg [ 332.32 KiB | Viewed 126 times ]

Of course its an improvement over stock but its far from optimal.