Head Gasket / Standard Pistons

A

ard1ey

Guest
Hi all,

Has anybody used one of the thinner head gaskets with original standard pistons? As far as I can find by searching standard is 1.4mm - I was considering the 1.2, as 1mm seems a bit extreme.

I prefer a quick pick up and a healthy mid-range so a slightly higher CR should help there and as the top of my engine is in bits it seems an ideal time to try and improve things - but if its going to muller the pistons there's not much point.

On the assumption that it'll work, has anyone got any recommendations for suppliers?

Thanks,

Ian
 
P

pulsarboby

Guest
hi mate, 1.4mm is standard oe gasket, but when its compressed (as its not steel) it will compress to 1.2mm, which is the thickness of a steel gasket ie hks and similar!
the idea of a thicker gasket is to drop the compression ratio to a safer level (with a turbo'd car) as there is more heat with a bigger bang!

most people will go for the 1.2mm steel gasket as you can up the boost to compensate.
but if you are running in excess of say 450bhp then the 2mm may be the best option as you will probably have a large turbo which can supply huge amounts of boost, and the 2mm gasket will drop the c / r significantly enough to run this amount of boost safely, which in a nutshell makes your pride and joy last longer!

i think robbie thunderblob knows where to get steel h/g cheap, if you go to hks as i did their about £200, but i wont get caught out like that again, i think thats a ridiculous price to pay!
 
Rishi

Rishi

Still waiting on some shims!
Would never do it that way... Build your engine to the compression you want through piston C/R, skimming etc.. Don't do it using a thick head gasket...

I'm using a 1.2mm head gasket, raised compression to my spec and 2.4bar on a GT3542R...

You can pick up a head gasket from AGRA Engineering for around the £100 mark...


Rishi

Rishi
Rishi
 
O

Odin

Guest
The trouble with running thicker 2mm gaskets is that the car will be pants to drive off boost, I would rather run a 1mm gasket if I can get away with it, The car will drive off boost much smoother, As long as you have the right cooling and a good mapper then you shouldn't need a low comp 2mm gasket......

That is a pretty old way of tunning turbo cars, Things have moved on a fair bit these days...


Rob
 
T

tro||

Guest
if your block has been decked and the head skimmed the 2mm gasket could be the right choice, just cos you're using a 2mm gasket doesn't mean its going to be a low compression engine
 
O

Odin

Guest
to|| said:
if your block has been decked and the head skimmed the 2mm gasket could be the right choice, just cos you're using a 2mm gasket doesn't mean its going to be a low compression engine
Click to expand...

Tell that to DP :lol: :lol: :lol: :lol: :lol: ...

Yes like you say if the block as been decked and head slimmed you could use a 2mm gasket, But I was talking about a standard block ;-) , I made the mistake of fitting one to my old pulsar :doh: , And it was rubbish off boost :cry: drove like a bag of bolts very slow to pick up and lumpy compared to how it was before with the standard head gasket.....

Best choice would probably be the 1.2 mm metal head gasket as fitted by 99.9% of rebuilt R's....


Rob
 
P

pulsarboby

Guest
you are correct in what your saying rob, but if the head needs skimming you will lose upto 1mm straight away (dependant upon head), couple that with a 1.2 h/g which will compress to just over 1mm and a big turbo running high boost, then something has to give which will either be the head or pistons if standard!

if he is keeping standard pistons and running no more than 1.6 boost with a few other light mods then i would just go for an oe h/g as this will quite happily do the job.

the idea of a 2mm h/g is to drop c/r if running massive boost, but as you rightly say the downside of that is that it will take an eternity to pick up when off boost, but if you were racing the car or doing track days a lot, the car will always be on boost, so its horses for courses really!

if block and head are skimmed then the 2mm gasket will compensate for skimming, so it really does depend on each rebuild and what you are having done!
 
D

Dan_GTiR

New Member
pulsarboby said:
but if the head needs skimming you will lose upto 1mm straight away
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If you need to take that much off the head to begin with, then it's not worth using that head, it'll be fooked!!!
 
P

pulsarboby

Guest
not necessarily, ive seen it done more than once to gain a higher c/r but valves tend to get a bit warm lol
 
A

AJ4

Guest
Thunder God said:
The trouble with running thicker 2mm gaskets is that the car will be pants to drive off boost,
Click to expand...
so what will happen when I fit my 8mm spacer plate 'gasket' ? :thumbsup:
 
O

Odin

Guest
AJ4 said:
so what will happen when I fit my 8mm spacer plate 'gasket' ? :thumbsup:
Click to expand...


Now you're just trying to be bl00dy clever :doh: :lol: :lol: :lol: :lol: ....





Rob
 
A

AJ4

Guest
quick change of subject, did you ever see that SR29DET engine with the 12mm gasket ? that was some good engineering.
 
stumo

stumo

Active Member
quick change of subject,did you ever see Rob with the 20 inch gusset? that was some good engineering.
 
A

ard1ey

Guest
Blimey, two pages of replies in a flick of a lambs tail - cheers gents.

My biggest worry is the higher CR putting too low a limit on boost pressure given my standard pistons. I'm looking to try for 350bhp (or more if it'll have it) out of this bottom end but as smooth and quick spooling as possible. I didn't realise the standard gasket compressed from 1.4 to 1.2mm anyway, but given that a 1.2mm steel jobby looks like the safe option.

Does anyone have any rough ideas about how much the 1mm gasket would affect possible boost levels? If not I'll follow the flock and go with 1.2mm and see if it blows up anyway :)

Hopefully engine management shouldn't be a problem, I've had a Power FC sitting here for years just waiting to go in and I'm planning to beef up the oil & water cooling while its all in many pieces. I just fancy seeing what I can get out of the stock bottom end. :D

Cheers

Ian
 
O

Odin

Guest
ard1ey said:
I just fancy seeing what I can get out of the stock bottom end. :D
Click to expand...

I ran 350-399.7 :lol: bhp on the standard bottom end for nearly 2 years before the engine finally gave up the ghost 8) , I think good cooling is the secret to engine longevity and very good fueling and ignition maps ;-) ....

If I was having to take the head off I'd be chucking some new forged pistons and good quality bearings in, While I was at it, Will save you having to do it again ;-) .



Rob
 
A

ard1ey

Guest
I ended up having a chat with Hiteq about standard pistons and gasketry, and the recommendation was to stick to 1.2mm. It sounds like the thinner gasket is asking for problems and I'm not actively trying to knacker the engine.

Completely agree about the forged pistons and doing it properly, I just fancy seeing what I can get before it goes wrong <prepares self for loud explosion :)>.

Thanks all, including the Captain

Ian
 
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