Head gasket thickness?

[Widge]

Any one know what thickness head gaskets are avalible for the M20?
Cheers

Oh and does anyone know of anywhere that will do a custom head gasket?

[ian332isport]

Any one know what thickness head gaskets are avalible for the M20?
Cheers

Oh and does anyone know of anywhere that will do a custom head gasket?

BMW list two thicknesses:

1.75mm & 2.05mm.

As for custom ones, not really sure. I'm pretty sure there was a place that advertised in Practical Performance car magazine a while back that would do Copper gaskets for any car in any thickness. Don't have the details to hand though.

Ian.

[Widge]

I'm just wondering if it would be possible to use a thicker head gasket in my 2.7 along with 2.5 -pistons,rod,block which usually gives a +3mm above the block, rather than the 320 rods which give -3mm and need the block shaving. This would also allow me to keep the extra volume!!


EDIT: Oh and thanks Ian

[Ant]

thicker headgasket is simply a larger weak spot dude, not a good plan I'm afraid

gives a bigger area for the gasses etc to push against.

Copper would cost more than the machining work dude !!, the capacity is dictated by bore/stroke so you'll still get the ful 2.7 even with a trim on the block

[Widge]

It may be a larger weak spot, but it should not be too weak if done correctly. Also people have a bad imge of thicker gaskets because they are associated with failures on FI engines. I am only talking about 3mm - BMW already does 2.05mm so it is only 0.95mm bigger.

And as for cost I have found a company in Clifornia who would make one from Copper for $90 + P&P.
Oh and I do respect your opinion ant and you are right, I'm just thinking

And I was thinking about somthing else when I said keeping volume! (what it was though I don't know)

[Jos]

Get a stainless steel ringed gasket if you are going that thick, 0.93mm don't sound like much but the pressures involved are very high, as Ant said the head gasket is the weak point on the block and the thinner the better. As said it would probably be cheaper to get the work done.

http://www.vacmotorsports.com/cgi-bin/v ... tem_id=510

3.56mm thick at $229 each, plus VAT + import but that could be an option.

[Widge]

That's a bit steep, The Gasket Works in California guarantees their copper gaskets if you use their sealing compound. I can see the problems this may present on an FI engine however it's only 10:1 ish compression, if the BMW one can workat 2mm, I think you may all be over emphsising the problem. Although the gasket is the weak point if done properly there is no reason why it shouldn't work. I kinda think if it is possible I should try it too, other wiseI will never know, and if it does work it could make making 2.7 from 2.5's very easy. Also Vacmotorsports admit tha ttheri gaskets go way beyond normal gasket capabilities for motor spor use and Fi which will be completly unnessicary on my engine.

[Ant]

Widge M8, we'd all be nowhere if we just followed like sheep, blaze a new path, it goes against the grain and is a useful option assuming the quality and price fit the bill.


Keep us posted

[Widge]

That's my thought ant, and if it goes pear shaped I'll order some custom pistons at some point and do it that way. The thing is I have a spear car so I don't mind experimenting. And if it works I could sell the gaskets!! I will keep you all posted, of corse it depends on how thick it will have to be. And I don't accept shoddy work so if it's not up to standard I'll send it back! I'm in no hurry!

[TOURINGDADDY]

how about getting an alley spacer made up and bonded to the block then just fit up rated gasket?!?!?!?!

[Widge]

It's an idea this site http://ferriday.co.uk/copper/copper.html basically says exactly the same thing but in copper, I'll lookin to it. Ferriday seem to know what they are doing and they do kinda wire sealing rings too which should make the gasket bloing more unlikley. They say you can just use the copper gasket too on it's own if done properly.

[E327UKL]

i cant help that doubt this conversion because of the longer stroke, surely a lot of the components would have to be lightened to compensate for the loss in willing to rev?? woudnt a short stroke be a better deal and raise the revlimit??

please let me know if im totally wrong here has have never gone this far with a bmw only 16v engines before now!!!

[Widge]

Well yeah, but the main way to make a 2.7 is by using a longer stroke crank from a 525e. So the stroke is longer and it is less willing to rev, marginally, and because the crank is cast not forged the rev limiter will have to be set at 6500-6750rpm any way. To make it rev more a 324td crank is needed, and they are not common. If you decrease the stroke you'll just go back to a 2.5. But the advantage of the longer stroke and the 2.7 is the increase in torque on the flattening of the max torque / power curve, making it far more tractable.

[Martinaston]

Someone mentioned a gaskets that cut's into the head and block as it's clamped down but i wasn't paying much attention.
Has anyone heard of these ?

[Widge]

Yeah that's mentioned on the ferriday site and http://www.headgasket.com/index.html
All riveting stuff, with modern materials and all that, and the fact I'm not turboing I really think this could work

[Martinaston]

Widge
I've not looked down the 2.7 route until now so i'm going to pick your brain if you don't mind

To get the 2.7 you just change the crank and con rods but don't re-bore the block, is that right ?

[Widge]

Correct it's the same bore (84mm - or 83.98mm as the haynes manual states !! ) You can either use an eta block (crank+rods+pistons) with a 320 head and just bolt it on. But for more power because of the way the 2.5 combustion chamber is made I am using a 325 block and pistons. The problem with this set up is if you use the 2.5 rods the 2.5 piston sticks up by 2-3mm above the deck as a result of the longer stroke of the crank. If you use the (apparently normal route) 320/323 rods the pistons are too far down the bore at tdc by 2-3mm so the block has to be decked or you get some horrendous 4:1 compression ratio. Also the 320 rods being shorter have the nasty habit of mking the piston skirt hit the crank webs so each piston has to also be machined. So by trying to get a thicker gasket I am avoiding decking the block and machining the pistons (or having custom pistons made is another way, which I'd rather avoid at Ԛ£600+ a set) and thus hoope fully saving money. It also means I could use any block or head or pistons or rods if i ever need to replace somthing. Any other questions I'd be happy to answer.

[Martinaston]

If your trying to keep the same combustion chamber are there any con rods from another engine that are 3mm shorter (not just BMW if its just rods) or would that cause the problem with the piston skirt ?