The whole site is here ...
http://www.geocities.com/izzmus/
but this is one of the most interesting writeups !
http://www.geocities.com/izzmus/shotgun/shotgun.htm
Hey Mike, I have never seen square edged peripheral ports before?
This isnt the new engine for the 323 is it??
Ive seen some serious internal porting but this takes the cake and cannot see the technical advantages of it,unless...they have not welded the pipes in plce yet....thats why its squared off so they can get a good outside weld and clean it up from the inside.must be
links have stopped working.
might be because its on geocities and they have a low bandwidth allowance.
if you read what he is trying to achieve in the writeups it explains that the ports are that shape to limit the port timing and make a less extreme power band "just for the hell of it" hence the use of a worn engine.
They use square ports quite alot in more expencive builds, They don\'t end up pefectly square as this would cause Apex problems but the idea is if the port is open it should be wide open! getting full advantage from the Port. But oviously making a Square P/P would cost twice as much as a Rounds one so its somthing you don\'t see every day and is usaly only that big on a N/a engine.
Its all about changing the power delivery to the Aplication your useing it for. You would not use that size P/P on a Turbo.
Ya but the apex seal does not like to be "suspended" on suh a great area,we used to have big round ports but 20% off the edges have to be on "solid ground",must have maximum area of apex in contact with housing but yu cannot have to much of an opening cos you cause a massive"vacuum" and you get less than you bargained for
could you not run a bridge down the centre of the port to support the apex seal ?
Not on a perip squire cos the material does not lend it to and ht eair flow will be stuffed
The apex problem is why the closing edge of the port should never be square, they also taper it off so the edge of the port is not sharp.
The thing is these sort of P/P engines are low life engines designed for big Hp they pritty much always have one pc\'s apex\'s in and get rebuilt on a regular as they usaly belong to No Buget race teams.
Gradual closing is what you ya mean.......................what you are saying tese boys are either on a revolution or we should not ive them the time off day
Yep, Kind of like the guys Exhaust Flat opening and curved Closing. Its hard to see on the Pics as he has not sleaved the ports yet.
Ceramic apex seals can handle the wide open spaces.They do not warp or flex over large openings.
The Mazda 787B had really big Peripheral ports and they used ceramics.
The port closing should be done better than a straight edge though,a radiused edge is the usual thing with a bevel too.Even with ceramics I do that still.
Regards
Carl