Head Gaskets and Big Boost

Suffolk944 · Jan 12, 2008

Can any of you guys who have modded engine output to say 300 bhp + ( or less for that matter) tell me whether as part of that process you have installed a head gasket such as Widefire or Cometic to cope with additional power or are you running with the standard ?

George Elliott · Jan 12, 2008

Jon, my '89 car has a DPW / Guru / 3Bar FPR / K&N and at 17psi I would estimate 285 good horses?
I ran it for 15k miles and it popped the Head Gasket. I felt it go at full boost at about 4300rpm in 3rd overtaking some traffic. The ambient temperature was about 25 degC in the summer.
The engine was at about 100k miles and the gasket was 50k miles old.
I replaced the Head Gasket with a cometic from Promax, and 18k later all is well.
Boost creates massive pressures in our engines, but I should add that the Victor Reinz? one I removed was basically a rotten old thing that had corroded badly. The cometic is Aluminuim/Viton coated and I feel it will last much longer.
There are more elaborate means of Sealing the Head, but for the money a Cometic is very good IMO. Wide fire will still corrode but the steel ring is wider than the factory original.
Dare I enquire, why you ask?
George
944T

edh · Jan 12, 2008

I would have thought a new standard gasket was good enough for modest power hikes - they rot over time, so any 15-20 y/o gasket is liable to go when you turn up the boost (or even fix the soft wastegate [

])

Suffolk944 · Jan 12, 2008

Dare I enquire, why you ask?

Well am considering investing in more power plus other stuff and I know the gasket is something I need to consider if I go down that route amongst a host of other things. My '44 currently puts out 274bhp but some more would be nice - whether I want to spend the sort of money required never to see it again on enhancements, rather than perhaps try a different car altogether is my current dilemma. [&:]

TTM · Jan 12, 2008

I assume your car is still fitted with its original K26/6 ?
If you are likely to take the head off for replacing the headgasket then fitting a bigger turbo would make a nice upgrade and further add sense to replacing the headgasket. Can't beat that logic can you ? [

]

sawood12 · Jan 12, 2008

ORIGINAL: edh

I would have thought a new standard gasket was good enough for modest power hikes - they rot over time, so any 15-20 y/o gasket is liable to go when you turn up the boost (or even fix the soft wastegate [])

I agree. The boost pressures we see on our cars to achieve 275 - 300bhp are not that big compared to what people are running on scoobys and Evo's so a stock gasket should be fine if your fueling and the rest of the engine is upto scratch.

I've read very mixed reviews about Widefires. They are a real Marmite thing - you either love them or think they are the spawn of Satan. I personally cannot see how they would be any better than a stock gasket. Cometics are basically the ultimate in head gasket technology avalable for our cars. However the downsides to these seem to be that they have less give in them than conventional gaskets so your block and head surfaces have to be pretty flat or you might get leaks or weaping (though they should be good anyway in my opinion). Also they are so strong that if something did go wrong with your engine under power the gasket wont give, whereas a conventional one might and save more expensive failures. Again this is a flawed opinion in my case because relying on a head gasket as a safety valve is not a good idea - the trick is to make sure your engine as a whole is upto scratch.

My view is that while the head is off, unless you plan to take it off again in the not too distant future then you may as well go for the Cometic. That way you take the head gasket out of the equation for future worries.

Suffolk944 · Jan 12, 2008

If you are likely to take the head off for replacing the headgasket then fitting a bigger turbo would make a nice upgrade and further add sense to replacing the headgasket. Can't beat that logic can you ? []

Yes indeed ! Would be going down the road of a Promax Level 3 kit which includes a new turbo amongst other things. Theres also a new exhaust, brakes and maybe some suspension tweeks to consider not to mention an electronic boost controller. It all adds up !

Diver944 · Jan 12, 2008

When the UK tuning market for 944T's started to take off about 6-7 years ago there were quite a few cars that blew head gaskets shorty after. In hindsight I think it was mainly due to old gaskets finally letting go and also a slight tendancy to run lean as the chip maps were not as sophisticated as today and didn't use 3 baf FPR's.

I've always been of the opinion that the head gasket is a useful safety valve and it's much more preferable for that to give way rather than pistons or valves melting [

] For that reason I would stick to a factory gasket for moderate levels of boost.

Having said all that I don't even have a gasket - eek!

MarkK · Jan 13, 2008

My red 89 turbo is running very well still with a cometic HG, no problems yet at a tad higher than stock boost,its such a small increase you could practically say it was still standard [8|]

Guest · Jan 13, 2008

Paul is right.
Don't use a Cometic as a prevention against head gasket failure. On Rennlist "Special Tool" took his Turbo 2.5 all the way up to 540rwhp on a standard gasket. The secret is to get the tuning right,
If you suffer bad pre ignition or mixsture problems you can actually crack your cylinder walls so any head gasket is not going to stand a chance. I went to Cometic as I have increased my bore size to 105.5mm and a standard 3.0 litre gasket is only constructed for 104.5. Only 1mm but tollerances do get fine.
By now I would recommend a new set of head studs with any head gasket replacement. These studs have held stretch for 20 years in some cases and metal does degrade over time. I went for ARP as they are cheaper and a lot better than stock.