Thick gasket

Any one had any experience with thick head gaskets used in turbo convertions to lower compression ratios?

 

According to 800G's there is no problem fitting these providing it's done properly. I "think" he means replace the head gasket with a thcker copper one, rather than sandwich a tinner copper gasket between two head gaskets.

 

I'm assuming you'd need an adjustable cam sprocket as well to get the cam timing right?

 

From an engineering veiwpoint if you're gonna turbo/supercharge an engine and want it to last, you should really uprate the pistons because of the added heat(a lot) and stress(a lot, also) coming from the forced induction. Sure people have done what you say, in fitting a thicker gasket and gotten away with it too, but it's like the storey of running a chev for a million miles without an oil change. I'd rather not. It's all up to how deep you pockets are really. Hope it's been helpful. Cheers.

 

Al lot of the yanks running 16v 2l ABA's just stack the ABA headgaskets - and a lot of them get mad power figures. Suppose all you've got to lose is two or three headgaskets......

 

You can use a stainless shim (commonly called a saver shim), the come in 0.5 and 1mm and can be used directly on to the head without using two head gaskets. The head must be perfectly flat (a good head will only need 0.003 removing to make sure the surface if suitable) and then weld seal (a type of automotive sealant that never dries but remains very sticky) is applied between the head and shim, this is very reliable and works perfectly well. I cant find the details of the company that makes them but they are readily available, ask Prof as I gave him the details and phone number a while ago.

 

saw the company at Autosport - will dig out the contact details for you if I can find them
I will also be producing some of these for various VW engines come summertime.
tt

 

gosnays or something wasn't it

 

Turbo technics run a thicker head gasket on the MK1 conversion, but on it's own it isn't enough to lower the compression far enough. They machine the pistons slightly to get the desired results. No double head gaskets here !! I got the pistonss machined locally on the last rebuilt (100,00 miles ago), only cost me 40 for the set to be done.

 

i will be able to get spacers machined up to 8mm which I believe is enough
tt

 

hell - 8mm - that'll allow some good boost then !!! Might be worth thinking about wiring ringing the plates if you need to stick a head gasket either side of the plate in case you run megga boost pressure.

 

found the number, Gosney's on 01708 740668. They have the popular VW shims on the shelf but will make anything you want. The last time I spoke to them they said it would be around 40-45 for one-off shims.

 

I bought a second hand set of PG pistons connecting rods and a new set of big end bearings. cost me 100. Drops you compression ratio to 8:1. Best way to do it for reasonable money. To buy this brand new from VW would cost 960 but I got the second hand parts from Germany from a corrado G60.Hole turbo setup cost me less than 400.

 

8:1 is very low - you shouldn't need to go that low
tt

 

Thats the standard compression ratio of a PG G60 engine

 

it's 8.5:1 which is still low

 

Sorry, I knew it was close. I just did the maths as its been a wile since I calculated it.

 

no need to apologise
tt

 

My Turbo Technics lump with the machines pistons etc runs around 8:1 comp ratio. Runs 1 bar boost on full chat and have had to retard the ignition a bit more to stop it from doing the usual daft things you get with detaonation etc etc. If it runs the std TT pressure it's fine and the ignition can be advanced back to where it should ala std TT settings. Low pressure turbo's get away with higher compression, so surely it depends on the boost pressure you run and other factors such as charge temp, fueling, ignition timing / advance retard and so on. [:^(] Already had some split pistons, so like the low compression approach !!!

 

Fancy this idea, did you do anyhting else MK1 8v turbo ? Might let me wind up the boost a little bit more !!