Re: barlow stage four set ups
Posted: Wed Oct 03, 2012 12:29 am
the width is adjusted in conjunction with the squish clearance to achieve your desired squish velocity
these are easily measured with readily available pc software and i guess theres freeware available now
the problem with them is they dont take account of the squish changing with operating rpm so a calculated 1mm may drop to 0.6 at 10,000rpm and throw the calcs
the main consideration is obtaining the correct comp ratio and widths and squish clearance are often tools used to adjust the volume unless designing a bespoke head from scratch,std heads often havent meat in the right place or skimming brings the squish area into the plug thread so working limitations exist
tests ive done show little difference narrow med wide and centre or side plug,many years ago i used software by tsr for doing heads but dont bother now,i test what works on the dyno/track/road ,also tested heads in mx from bud/vhm/factory which had a whole manner of designs but the basic c.r. was at the core of what worked
compression also works with or against ignition timing and pipe design particularly stinger size and fuelling which makes for a messy testing regime its like trying to unlock a combination lock trying to find what works and interestingly reveals there are many ways to skin the cat,so id guess harry has dropped on a combination that works for him and his customers are happy with
these are easily measured with readily available pc software and i guess theres freeware available now
the problem with them is they dont take account of the squish changing with operating rpm so a calculated 1mm may drop to 0.6 at 10,000rpm and throw the calcs
the main consideration is obtaining the correct comp ratio and widths and squish clearance are often tools used to adjust the volume unless designing a bespoke head from scratch,std heads often havent meat in the right place or skimming brings the squish area into the plug thread so working limitations exist
tests ive done show little difference narrow med wide and centre or side plug,many years ago i used software by tsr for doing heads but dont bother now,i test what works on the dyno/track/road ,also tested heads in mx from bud/vhm/factory which had a whole manner of designs but the basic c.r. was at the core of what worked
compression also works with or against ignition timing and pipe design particularly stinger size and fuelling which makes for a messy testing regime its like trying to unlock a combination lock trying to find what works and interestingly reveals there are many ways to skin the cat,so id guess harry has dropped on a combination that works for him and his customers are happy with