Head Gasket failure...
Turbo Mini Forums

Hi Robert,

I'm not expert but I can't see any melting of the gasket? Would it always show as melting?

Maybe I should turn the boost down, maybe its just too much heat even with the water. Can anyone check that my CR calcs are correct incase I have get them wrong?


Starting to think about a different route, getting sick of this..

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

mm maybe, the head was originally from morspeed.... thinking about getting my hands on a 940 and having a word with Phil to work some magic on it. and then work out what is needed to get it to work on my block, and get the work done over the winter...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Are you sure the threads on the studs arent bottoming out ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I will double check the studs when I removed the head again. I'm sure that I checked it

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I'm trying to find a link to a guide I saw where they did a 11 bolt conversion with a small bore head. The left side needs sleeving after drilling, but on the thermostat side they only drilled through the bottom face and inserted a bolt through the thermostat housing.

I don't know how common this is; has anyone else seen this done? I know it sounds hacky, but maybe use a 10th bold as a quick fix. Not a great option, I know.

EDIT: found link...

Edited by PhilR on 28th Sep, 2014.

I have seen that, and I know GR is well respected but it looked just as hard to convert to a 940, plus I with a 940 I might be able to loose the decom plate.

Not that I'm that convinced that the plate is the issue.. but at this point in time who knows..

Edited by gr4h4m on 28th Sep, 2014.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

This is an interesting extract from the link above


One of the problems with the small bore head when a lot is machines off the face, is they leak or blow the head gasket out the ends. So, this is how to convert a small bore head to an 11 stud/bolt setup.

Just a note on machining the face of the head. I never take any more than 60″ – 80″ off the face of the head as it flexes and warps to much and you end up losing more than you gain with gasket seal.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Boom! there you go!

I'm sure Vizard talks about taking too much off the face, he gives finished casting thickness dimentions, so could be easy to have a quick measure and see where your current head stands you with the information above.

I know Simon Morson did some good head work, but did he know enough?.....

any chance that some of the coolant from the last blow up was still in there so still read as exhaust?

be very interesting to see the head face thickness measurement .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Remember that fitting a 940 head may involve pocketing the block.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Yep I understand it's going to be a big update for the winter, I was thinking of pulling the engine as it has a small leak at the 1/2 moon seal.
My thoughts are :

Pocket the block
Block and redrill any water ways
Drill and tap for 11 studs

All at my local machine shop

Then get hold of a 940 and have the chambers increased and drilled for 11 studs

Put it all back together and try to get a better tune in the car.

Not sure what extra testing I can do to get to the root of the issue

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Despite the damage the car sounded very nice on track, so worth it just for that.

Thanks and that was only 1/2 throttle. It was very frustrating not to floor it.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Ok I have done some rough and ready measurements and I make it 68.03mm or 2.6785" so it's .0715" small than standard.

Now I don't have a big mic to take an accurate measurement as the head is still on the car but headgasket is poking out a little so I took it with a vernier caliper so it's not super accurate... I will try again when the head is off the car.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I am not sure as to why your gasket keeps blowing out but I can show you how I calculated my CR in the photo attached. I too run a suck through S/C with injection and also used a cometic head gasket (Pt# C4146-92) to lower the CR to 8:38 according to my formula and measurements. Mine is a 1275..originally an SPI though.
I also used the hylomar gasket sealant spray as my mating surfaces weren't finer than 50RA (Roughness Avg)
So far so good on mine.

Edited by Dutchy1978 on 3rd Oct, 2014.

Thanks for the info.

What boost psi are you running?

Also where have you placed the injectors, was it using the k6 emerald ecu?

Graham

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Graham, I am running the original mini R53 pulley which shows up as 11-12 psi on my boost gauge which it picking up from the inlet manifold right before the head.
In terms of injectors, one injector at the mouth of the supercharger for idle and low revs and two more after the S/C in the inlet manifold for high revs and boost.
Also running an Autronic SM4 fully programmable ECU which has been great. Not necessarily easy to use at first but there is a whole forum dedicated to it so everyone on there is extremely helpful.

if it where me id get rid of anything in between the block and head faces and put a brand new ACL mono torque gasket new arp studs with the old lube

id not worry about the comparison ratio unless its more than 12 or so

you will be surprised how much twist the block or head can have with a blue composite mono torque gasket in there hell ive got a reused one in my current engine as i didnt have a new one and wanted to run the engine in while i finish the turbo head and then it will get a new gasket and a head that the valves arent fucked on lol

i dont thing the copper is soft enough to take up the slop in the however mating surfaces you have what is it block gasket spacer gasket head? err block gasket head.. i think you have given yourself an headache for no reason

compression is good if you control the intake temp and fuel/timing its free torque... i will never build a low compression engine ever just bring the pistons flush the gasket thickness will give a good quench for that last bit of the stroke pulling heat from the charge and dont give the chambers any sharp edges to cause issues run a cold thermostat and make sure the water ways are free from shit

compression is desirable in my opinion it makes a more effciant engine and gives more grunt threw the full rev range

hell the mini cant breath well no matter what you do to the 5 port head its allway wanting more volume so take advantage of what it can get in there and extract as much of the combustion pressure as u can the higher the comp the less combustion pressure is wasted blowen down the exhaust also more compression lets you have what manny whould call a small exhaust valve that lets you have a bigger intake valve

point is dont be scared of compression unless you know you have problems caused by it i dont beleve you need all that stuff between the block and head just make sure there flat and get a new acl gasket in there a compiste one not the copper or what ever ones it needs to be soft in my opinion how else is it going to push and compress to fill those tinny bits that evry head nad block have no matter how well its milled of faced what ever

I've tried one of the ACL gaskets and that went with a crease fro the fire ring to the water way....

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!