Spuds Porting and Tuning Thread

[Sawchip]

The golden ratio is only something about what works in nature or is pleasing to the eye not what is efficient in mechanics.

There is truth in that…however..It is something that crops up in the design of buildings..car design ..in fact Design in general.

Sure you have seen the comment "If it looks right ,then it usually is right" I don't say there is a full on formula here ,but i have noticed a posable connection in proportion to things that work well.

[peatff]

There is truth in that…however..It is something that crops up in the design of buildings..car design ..in fact Design in general.

Sure you have seen the comment "If it looks right ,then it usually is right" I don't say there is a full on formula here ,but i have noticed a posable connection in proportion to things that work well.

 

It crops up in these areas as pleasing to the eye not efficient, it also crops up in supermodels and animals. Physics follows different rules. If something is aesthetically pleasing doesn't mean it will work. Da Vinci drew some nice machines but they would not fly. I thought it was "it it looks right then it probably is right"

[MattyF]

Good point.

 

 

 

Also the reason stihl drills and hedge cutters that have an ignition rev limiter foul their exhausts with tarry unburned fuel if people insist on holding the throttle open all the time.

 

 

Isn't that what you do when you cut a hedge though? I would not buy another Stihl hedge cutter as long as I live any how.

[spudulike]

Point taken on the limitations of piston/ring and placement /geometry of the cylinder as you find it from the manufacturer.

Im sure you have a tried and tested tuning rule, plus the art of cylinder work is far from a simple 1 sentence description as to how and what to do. Do you feel that the final outlet on the muffler has to have a ratio in a certain region to give the best results with your port work so as not to still restrict to much.

Would it all be for nowt if the outflow wasn't enough ?

This 70-80% rule of thumb seems to crop up a lot.

 

I have the 70-80% figure in mind and take a rough view on it but don't get the Verniers out to measure it! Any decrease in exhaust pressure/better flow is good, the exception being tuned expansion pipes!

[Eddy_t]

Think cut off saws have a limiting coil , more so than some saws , so the disk cutter can not spin above the printed max revs on the label . Thats why when they are revving in fresh air they misfire .

 

 

Cut-off/disc cutters are governed by the carb, mostly as they were just repurposed saws until a few years ago!

 

 

Sure you have seen the comment "If it looks right ,then it usually is right" I don't say there is a full on formula here ,but i have noticed a posable connection in proportion to things that work well.

 

 

I always thought the phrase was "f*** it, that'll do!" I'm slightly confused by your ratio, is the exhaust port the 1 or 1.6?

[spudulike]

Spudmaster Flash and the Furious File - Silver lines....don't do it:lol:

[Lazurus]

Spudmaster Flash and the Furious File - Silver lines....don't do it:lol:

 

Great song, your giving your age away.....

[spudulike]

Great song, your giving your age away.....

 

I know:lol:

[Sawchip]

It crops up in these areas as pleasing to the eye not efficient, it also crops up in supermodels and animals. Physics follows different rules. If something is aesthetically pleasing doesn't mean it will work. Da Vinci drew some nice machines but they would not fly. I thought it was "it it looks right then it probably is right"

 

Hope this pic came out..not good with the way it works yet.

[Sawchip]

Cut-off/disc cutters are governed by the carb, mostly as they were just repurposed saws until a few years ago!

 

 

 

 

I always thought the phrase was "f*** it, that'll do!" I'm slightly confused by your ratio, is the exhaust port the 1 or 1.6?

On a 262 xp ( i think it was anyhow ) exhaust port i had the Sq mm area at 380 and the output on the muffler calculated at 254 sq mm giving about 70% of the exhaust port area.

This gives the 380mm as the 1.6 part and the 254mm as the 1 part . Much the same as saying 2/3 rds of the start number (380mm ).

Now I'm not saying its scientific in its nature but you can find this natural ratio a lot in many things even if you don't start with the intention in mind.

Anyhow there we go..some interest..or none up to you.