head skimming

[Andy652]

I've got a 1.0 with the low compression head and I was wondering if its possible to skim it the right amount to make it the same as the higher compression heads, or if there is more of a difference between the two heads than this?
also, how much can be taken off safely before you start running into problems and what sort of gains can be achieved by this?

thanks in advance

 

[joesouthgate]

well the difference between the low comp and the high comp MA10 is 5bhp so i would of though that could be gained!

 

[frank]

andy

i had at least 2mm skimmed off my 1.2, but the adjuster was near max, even with a new belt and you need to advance the valve timing to suit, ideally

 

[daveeeeee]

might just be easier to get hold of the higher comp 1.0 head, or even the 1.2 big port head. theres no certianty as to which head is the best to use. from what i've gatherd from the website the 1.0 head with some work done i.e ported, skimmed due to the hemispherical design, mixes the fuel and air more efficiantly (apparently). but sticking the big port 1.2 head would give good gains also.

 

[Andy652]

thanks guys. I did realise that youd gain about 5hp if it got the same compresion as the high compresion head, I'm not that dull lol. I meant what could be gained from skimming it as much as possible

 

[jowley]

your local engine serives will know the best amount had mine done once took it down so there was a slight bit higher than the valves when sat

 

[drummersiy]

mine was 4mm and added around 8bhp i think but yea its good and it needed it cost an alreet amount considdering i got a reconditioned radiator and everything else that is needed

woop

 

[athmene28]

I am sorry if I sound dumb, but what do you mean by skimming the head? I have never heard this term before. I am sure that it is something that they do here as well but maybe they have a different term for it here in Canada. Like trunk and boot for example. What is all involved in doing this? I have a 1.2 in my car.

 

[whipit]

Well i had 1.6mm skimmed off of my ma10 head then put onto a ma12, runs ok no problems so far.

 

[Andy652]

athmene28, can't give you a very good explanation, but its pretty much when a small amount of material is skimmed off the cylinder head, which increases the compression ratio, which increases the power. If you want a better explanation search on the internet and there'll be one somewhere

 

[nef1000]

hi,
please dont take this as gospel but iirc, the low comp engine also has dished pistons as opposed to flat on the high comp. i was recently thinkin of skimming a low comp right down but dont think its worth it. start with the best engine and make it better. again, please check this with others. i will however, look on my low comp eng tonight when i get home to comfirm.
ne

 

[daveeeeee]

i dont think that anyone has confirmed this, i think that it was the k11 with dished pistons.

however i have no proof but i've heard that with the same compression dished pistons can be better? as i say this is just what i've heard

 

[Andy652]

mine was 4mm and added around 8bhp i think but yea its good and it needed it cost an alreet amount considdering i got a reconditioned radiator and everything else that is needed

woop

was that deffinitely from a low comp ma10 head, and were there no problems when it came to tensioning the cam belt?

 

[drummersiy]

no its a super s MA12 engine.. and was all done at the garage for me

 

[Andy652]

I've bought a spare head from curtis now and I'm planning on getting it skimmed later this week. If possible, could anyone tell me for certain how much they've had taken off a low comp ma10 head (and put on an ma10 block, not an ma12)?
I ask because It'll be easier, cheaper and quicker for me to go straight to the engineers. If noone can give me a deffinite answer then I'll go to the garage first and get them to find out how much I can have taken off. Unfortunately the engineering place wont do this, they'll just take the head and take off how much I tell them to.

 

[frank]

andy

mine was at least 2mm (iirc it was 100 thou or 2.5mm), but that was an ma12.
imo, you should aim for 10.5:1 c/r, and to do it properly, you need a perspex cover over the chamber (greased up, and a small hole in the middle, and a pipette to measure the combustion chamber cc