portin / polishing

[James B]

cars in bodyshop, was thinking of going and whacking the head off before work commences down there and having a go at a DIY port polish. Found a good in depth guide on the net

http://www.sa-motorsports.com/diyport.shtm

but where would i get the abrasion kit mentioned from and would anyone say i was a fool for considering to do it myself??

James

[James B]

by the way its a 1.4 8v, but also have a 1.2 head perhaps this would be a better option to start the work on??

[-Bruce-]

you could possible do it yourself but who knows if it will benefit you!!

and if you got a 1200 head there then practise on the 1400 and then use the 1200. i dont know how to port etc but im sure the more you do it the better you get.

bruce

[Stuart]

read some books by david vizzard first

it takes time and its an art

but going form a 1.4 head to 1.2 head will effectively give you a free ported head.

maybe just whip out some of the casting marks, match the manifolds and DONT leave a shiny finish as it screws airflow up.

[DrivingSpanner]

ditto - take you time, it'll take far longer than you think and be patiant, sometimes less is more!!!

[m.d.]

took me weeks of doing an hour of 2 every night to do mine. well worth it tho

[James B]

maybe just whip out some of the casting marks, match the manifolds and DONT leave a shiny finish as it screws airflow up.

whys that, only reason i can think of is that a rougher finish would cause more air turbulance which will incease the detonations, i think??? :o

James

[Stuart]

a polished surface can slow down laiminar flow which will cause the fuel to drop out of suspension with the air, which will lead to less power as there is less air and fuel getting in at a given rpm.

with a rougher surface (not mega rough, prehaps like the finishe of non shiny plastic) the air can be turbulent and this means the A/F mix is in constant mixing and you get a better A/F mix in the cylinder, which will give more go.

thats the theory anyway.

ok F1 heads a near mirror polished, but thats because they can compensate for the laminar stalling by increaseing the gas speed due to silly rpm.

[DrivingSpanner]

ok F1 heads a near mirror polished, but thats because they can compensate for the laminar stalling by increaseing the gas speed due to silly rpm.

the same can also be applied to a turbo or blown engine as its forced induction which will also increase the air flow speed.

Every engine is different tho and sometime the theory doesnt apply,

Inresponse to removing the casting makes and flashes, this is because they are restrictive and will slow the air down, can be a bit like hitting a small wall at the side of the port...

[James B]

ok so where do you think i can get the abrasive gear from

[Stuart]

use a dremmel (or similar)

failring that DT do a "porting pack" of carbide rolls etc for just removing casting marks etc. any serious work neers tungston carbide burrs and a lot of care.

[DrivingSpanner]

use a dremmel with a flexi drive, so that you can get around the corners more easally. buy some fairly small round nosed burrs (10mm ish) and keep it well lubed with wd40 to stop it clogging.... then buy some abrasive paper wheel for smoothing and finishing.

[James B]

ok cheers lads wel ill keep you posted as to how it all goes

James

[dan-nova]

u wana just sand down the ports and make them real smooth this will give better fuel and airflow into the cylinders and maybe consider skimming the head aswell as this will generate more compression and therefore better more power given after the power stroke

[VXRALLY]

u wana just sand down the ports and make them real smooth this will give better fuel and airflow into the cylinders and maybe consider skimming the head aswell as this will generate more compression and therefore better more power given after the power stroke

you make it sound so easy dan, it takes years of pratice to get it right. but hay lets try it your way and fek our heads! :wink:

[a11ova]

i would get it done properly by big bill myself. less risk of cocking it up then :)

[Stuart]

its quite straight forward to get good gains yourself, but it takes an age to do it right.

bill will offer a fast and proven solution, but obviously at a cost. but then work it out and your 40hours work that you put in could translate to ?500 or what ever.