Metal head gasket - should I stick with standard 10:1 compression ratio or go for lower 8:5:1

[matth76 1]

Hi

I'm having a metal head gasket fitted to my Golf VR6 this week as opposed to the less reliable standard plastic head gasket. The garage has said if I want to get a supercharger fitted in the future it could be an ideal time now to fit a lower compression ratio thicker metal head gasket at the same time (for no extra cost).

The head gasket I'll be getting will be metal no matter what ratio I decide on. My question is should I just stick with the standard compression ratio of 10:1 or should I have a lower compression ratio of either 9:0:1 or even lower at 8:5:1 which ultimately would be able to withstand huge bhp but in the short term while I don't actually have a supercharger make my car lose power and make it sluggish.

Really I need to know how much power can a standard compression ratio of 10:1 metal head gasket withstand - bhp and torque wise? Is it worth going to a lower compression to save money in the long run? I won't be getting the car supercharged for about 6 months so it needs to be drivable without being really slow. Ultimately I want at least 300bhp when I do get it supercharged.

Thanks for any help, as I need to let the garage know what ratio I want in the next two days.

Matt

[The1andonlygav 0]

go for the 9:0:1, if you are serious about getting 300bhp. It will save you doing it in the future, and be a nice little mod.

[mightyvr6 0]

If your not goin over 10 psi I'd say fit a standard head gasket. If you fit a low comp gasket you will need an even smaller pulley to get the same power.

[matth76 1]

Yeah you may be right. Going for 8:5:1 may be a bit radical... i.e only if I was going for very high power. I'm only looking for 300bhp which is ample. I don't really want to go much over due to lack of traction making it pointless. Although 8:5:1 is the toughest and able to withstand the most boost, I agree the higher compression ratio of 9:0:1 may be a bit more sensible and perfectly adequate. Does anyone know how much power loss I may get in total with this lowered compression ratio while my car is still standard (i.e without a charger)?

[matth76 1]

If your not goin over 10 psi I'd say fit a standard head gasket. If you fit a low comp gasket you will need an even smaller pulley to get the same power.

Thanks for all your replies guys. Will 10psi boost easily see my car reaching the 300bhp mark (with other mods of course)?

I'm beginning to think sticking with the standard ratio of 10:1 will be fine and it will be much tougher due to it being a metal head gasket... am I right in thinking this that the engine block will be tougher due to the replacement of the standard head gasket (which is mainly made of plastic) with that of a metal one?

I'm having the gasket replaced due to slight signs of dampness around the engine block where the head gasket is. Storm Developments said replacing it with a metal head gasket should make my engine 'bullet' proof. Is my car going to be much more reliable with the metal head gasket - i.e could it potentially take more power when I come to adding a supercharger?

Thanks again for your help guys.

[mightyvr6 0]

Metal gasket is definitely better although I've got a normal paper gasket and that seem ok after doing 30,000+ s/c miles.

Maybe fit some racing headstuds too so the gasket is well clamped down and you won't have to change them if you decide in the future to lower the compresiion.

[matth76 1]

Thanks. I'll ask them to see if they can include them too. Do the head studs make it a much better seal? Are there any other parts that I could ask them to upgrade to tougher ones while they are doing the head gasket... such as bolts or anything similar? Are they likely to need to skim the gasket before fitting it?

[matth76 1]

Can anyone help? What kind of psi boost would be required to reach 300bhp? Are we talking around 8psi or less?

What other internal uprated components could I have replaced while my head gasket is being done other as well as head studs? Are fitting new rods easy to do while the head gasket is being done? Basically I want to take this opportunity to make my engine lump as strong and reliable as possible while my head gasket is being done as it's not often half the engine is taken apart !dodge

Thanks for any help.

Cheers guys.

[mightyvr6 0]

Might be worth fitting some uprated con rod bolts (arp). I reckon you need at least 8-10 psi to get 300hp on standard compression.

[matth76 1]

Are the uprated con rod bolts the same bolts used to clamp the gasket or are these different bolts? Do you or does anyone know how much ARP uprated conrod bolts or ARP headstuds are?

Would uprated bolts be better than uprated headstuds then?

Cheers

Matt

[mightyvr6 0]

The rod bolts are different to the head bolts. The rod bolts hold the con rods together on the crankshaft. The head bolts are longer and clamp the cylinderhead to the engine block. ARP make both sets of bolts for a vr6.

The arp head bolts are studs and are fastened using nuts which is differnet to normal stretch bolts with have heads (like a normal bolt).

[apd 0]

stealth recommend racetec head bolts with a copper head gasket.have this on mine-303bhp.seems to do the job fine.running 8.5psi boost.