MLS headgasket enquiries.

[205dtub]

So the story goes,  I bought a supposedly 86k engine.  Only supposedly because you can't trust any of the hoodlums that own dturbos in N.I.
Made the decision to strip and inspect the engine, port and polish head etc instead of dropping it straight into my 205. Everything is grand. Head perfectly flat,  measured with engineers straight edge,  valve stem to guide clearance all good.  Genuinely seems a fit engine.  
However,  the headgasket fitted has three notches.  After measuring piston protrusion from the block with a dti, this seems to thicker than necessary.  It is also a Multi layer steel gasket.  I have built plenty of engines but it's my first xud9.  So my questions are,   does anyone with any experience think it is worthwhile to fork out the extra for a mls gasket? 
Did this come as standard?  I doubt it,  I imagined surely they would have come from factory with a composite headgasket?  It appears to say payen but very faded,  a decent brand.  So not standard?  Head has no obvious signs of a skim and supposedly had 86k from a phase 2 306,  so I didn't imagine it would have had a very hard life although the lucas pump had definitely been fiddled with. 
So, is it worth paying extra to fit a mls gasket?  I think I will but what are the opinions on the matter. [attachment=21657][attachment=21657]

[bashbarnard]

Mls or don't do it. Hold more boost better quality. Worth the extra bit of cash

[zx_volcane]

For sure put in an MLS - absolutely no reason not to,

Are Payen MLS not oem?

I'd go Payen, Ellring or Victor Reinz - I've used all three brands on high power builds and all have been fine

[Niall]

Payen are OEM for the GTi iirc which is also MLS so i would imagine that is a standard gasket

[anto]

Ive used Payen on mine and its seen 30psi regularly so it should be fine.
Most people actually go for a 5 notch (ie thats what the motorfactor will give you) so that there is even less chance of pistong meeting the head.
I had to request a 3 notch for mine.

[205dtub]

Thanks for the replies guys. Appreciate it. I'm on a tight budget but I think I'd rather replace with at least what was there as the engine was running fine before I stripped it.
As far as I was aware fitting too thick a gasket will induce knock obviously due to lower compression, I will stick with three notch as it was there before and seems more than necessary to meet the tolerances of the haynes manual.

[Chairchild]

increasing the piston to head clearance does three things:

1) reduces static CR, so an immediate (if minimal) performance drop

2) reduces the amount of squish, which whilst not *as* important on an IDI diesel, it still reduces performance, ecomomy, and increases emissions

3) removes all chances of contact-cooling - where the piston gets so close to the head, it's considered as touching - whereby a minor amount of cooling occurs to the crown of the piston.


It won't induce knock - only the fuelling can do that. As you've got the head off, use a DTI gauge to measure piston protrusion from the block, and buy the best suited HG (covered by Haynes) for the highest piston

[vinny]

use the mls its loads better just buy the thickest one if ur running more boost than standard

[Chairchild]

use the mls its loads better just buy the thickest one if ur running more boost than standard

And your reasoning behind this is?

[205dtub]

I had already measured piston protrusion, getting about 0.6mm. According to the manual the gasket that was on it was thicker than required, but I've a feeling it was the standard gasket. I will go mls, hopefully elring or payen if I can get my hands on one. Sticking with three notch as it was working before and I'm not going for proper mental power figures.

[vinny]

use the mls its loads better just buy the thickest one if ur running more boost than standard

And your reasoning behind this is?

higher boost increases the cr thats why on petrols they lower the cr to run more boost the amount it would lower ur static cr using thicker gasket aint worth talking about and also if ur gonna turn more revs ud be suprised how far the rods stretch so a few thou more clearance would not be an issue.

[Chairchild]

CR is a simple measurement of volume - it has nothing to do with boost.

[Tom]

Boost increases cylinder pressures doesnt it? But the actual compression ratio is measurement of squashing all the air from bottom of the piston travel to the top? Correct if im wrong...

Always use MLS, that goes for every XUD owner out there.


Edit... Yep that.

The compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity.

[205dtub]

Cheers for the replies lads. Now to wait for payday to buy the buggering parts. Just after buying a 600x300x76 twin pass front mount on impulse.

[vinny]

Boost increases cylinder pressures doesnt it? But the actual compression ratio is measurement of squashing all the air from bottom of the piston travel to the top? Correct if im wrong...

Always use MLS, that goes for every XUD owner out there.


Edit... Yep that.

The compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity.

yea ur rite m8 i worded it wrong should have said effictively it does because ur compressing pressure