Has anyone tried this type of porting?

[Smokingwheels]

Way back in 2002 I ported an engine with a wire wheels. Long story but I ended up destroying the crank before I could control the strange timing curve.
See blue line on graph but this was with the compression up at 12.5:1.

In 2005 I tried again on another engine which is still running today but has been sabotaged once with silicon in the oil.

My timing on my engine runs similar to this pic

My engine is really touchy with the spark timing so its not set and forget..
If it goes out of tune it uses more fuel than it should like now I have lost one of my load switches to adjust the timing.

It used to have more power that normal until I overheated it in 2005.

I have been keeping some records over the years and have updated my fuel log with the good ones, sometimes it runs worst that a model T Ford...
1984 Nissan Bluebird wagon LX Gas Mileage (Smokingwheels) - EcoModder.com

I have had to put a second fuel pump in to keep up with WOT when it was in peak condition.

Warning if you want a temperamental engine that performs micricals sometimes then try this to you head ports and inlet manifold if you have a spare one and can program an different timing curve into you ECU.

[Daox]

Only your last image is loading for me.

[shovel]

I'm not sure I understand what you're suggesting, you mean take off the intake manifold and use a wire wheel to rough up its interior and this makes the whole engine finnicky about timing advance but better on fuel?

[Smokingwheels]

Originally Posted by shovel

I'm not sure I understand what you're suggesting, you mean take off the intake manifold and use a wire wheel to rough up its interior and this makes the whole engine finnicky about timing advance but better on fuel?

Yes it does have an improvement on fuel but requires lots of maintenance with the timing with the current system. I have with a laptop controlling the timing.
I wrote a program in quickbasic 4.5 and interfaced the printer port to my cars ignition system.


A modern EMC system with knock sensor may give less trouble but I haven't got that far yet.

[RobertISaar]

you don't adjust timing based on vacuum/MAP, only RPM?

that's just like a distributor with it's vacuum advance disconnected... works great when at full throttle, horrible at anything less than that.

[Smokingwheels]

Originally Posted by RobertISaar

you don't adjust timing based on vacuum/MAP, only RPM?

that's just like a distributor with it's vacuum advance disconnected... works great when at full throttle, horrible at anything less than that.

The program looks at what speed the engine is doing to get a baseline timing value for that rpm and the the 2 vacuum switches tell the computer how much to advance the timing off the baseline, I know its not as good as a MAP sensor but that's how its been running for all the time the computer has been fitted.