headgasket replacement diagnosis
Turbo Mini Forums

right i stripped down the car got the head off and it has gone between snd and 3rd bore and also on the outside back edge of 1st and second so its pretty bad... im going to get the head skimmed jsut incase... is this all i should get donwe before putting it back together?

also there is water in the engine?
more that any other headgasket i have done :S

quick replies will be appriciate

oh one more thing rough price on skimmming a head?

Make sure that you don't get too much taken off that head or your CR will hit the roof.

Edited by theoneeyedlizard on 22nd Apr, 2008.

In the 13's at last!.. Just

£50 pounds i think

http://www.Zeemax.com

a quick flash to check flatness costs £20 at the place near me

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

same here, cost me £20 for a 10thou skim

20 quid but is that wit hthe valves out?

if your head gasket has blow where it has, i suspect that it is detonation issue if it is a turbo engine

skimming the head will compound the issue big time you need to lower the compression enlarging the combustion chambers

whats the spec of you engine .... is it a turbo, a guess it is

Edited by BENROSS on 22nd Apr, 2008.

yes it is a turbo... its a 1293 running fairly standard...

how do i sort the compression out as i fort i would need my head skimming

also what causes detonation and how can it be cured

you need the head checking to make sure its flat!... if this is the case

i suspect you have upped the boost a tad

i suggest you need the compression lowering
i have cariied this out for many members on here

i can place 28 cc in the combustion chamber for you, pm me if you wish giving you a cr of around 8.5:1 insted of 9.4 ish
the standard gives combustion chamber is 21.4
you will be able to run higher boost say some 16+ psi with intercooler if the rest of engine and gearbox will stand it

right detonation ...........

Normal combustion
Under ideal conditions the common piston internal combustion engine burns its fuel/air mix in the cylinder in an orderly and controlled fashion. The combustion is started by the spark plug some 5 to 40 crankshaft degrees prior to top dead center (TDC), depending on engine speed and load. This ignition advance allows time for the combustion process to develop peak pressure at the ideal time for maximum recovery of work from the expanding gases.

The spark across the spark plug's electrodes forms a small kernel of flame approximately the size of the spark plug gap. As it grows in size its heat output increases allowing it to grow at an accelerating rate, expanding rapidly through the combustion chamber. This growth is due to the travel of the flame front through the combustible fuel air mix itself and due to turbulence rapidly stretching the burning zone into a complex of fingers of burning fuel air that have a much greater surface area than a simple spherical ball of flame would have. In normal combustion, this flame front moves throughout the fuel air mix at a rate characteristic for the fuel-air mixture. Pressure rises smoothly to a peak, as nearly all the available fuel is consumed, then pressure falls as the piston descends. Maximum cylinder pressure is achieved a few crankshaft degrees after the piston passes TDC, so that the increasing pressure can give the piston a hard push when its speed and mechanical advantage on the crank shaft gives the best recovery of force from the expanding gases.


Detonation — abnormal combustion

When unburned fuel/air mixture beyond the boundary of the flame front is heated and pressurized by the advancing flame front for a certain length of time, detonation occurs. It is caused by an instantaneous, explosive ignition of pockets of fuel/air mixture. The cylinder pressure rises sharply beyond its design limits, and if it is allowed to persist, detonation will damage or destroy engine parts. The deleterious mechanisms range from particle wear caused by moderate knocking, to holes punched through the piston or head caused by serious knocking.

Detonation can be prevented by the use of a fuel with higher octane rating, richening the fuel/air ratio, reducing peak cylinder pressure by increasing the engine revolutions (e.g., shifting to a lower gear), decreasing the manifold pressure by reducing the throttle opening, or reducing the load on the engine. Because pressure and temperature are strongly linked, knock can also be attenuated by controlling peak combustion chamber temperatures at the engineering level by compression ratio reduction, exhaust gas recirculation, appropriate calibration of the engine's ignition timing schedule, and careful design of the engine's combustion chambers and cooling system. As an aftermarket solution, a water injection system can be employed to reduce combustion chamber peak temperatures and thus suppress detonation.

An unconventional engine that makes use of detonation to improve efficiency and decrease pollutants is the Bourke engine.


Pre-ignition

Pre-ignition (or preignition) in a spark-ignition engine is often confused or conflated[who?] with engine knocking. In fact, it is a different phenomenon, when the air/fuel mixture in the cylinder ignites before the spark plug fires. It is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events. Dieseling or run-on is the same phenomenon, but refers to the engine continuing to run after the ignition is shut off with a hot spot as an ignition source for the fuel air mixture. Because both preignition and engine knock sharply increase combustion chamber temperatures, either effect can increase the likelihood of the other effect occurring. Given proper combustion chamber design, preignition can generally be eliminated by proper spark plug selection, proper fuel mixture adjustment, and periodic cleaning of the combustion chambers.

HOPE THIS GIVES YOU SOME INSIGHT

BENROSS you are a legend lol

so i need to get my head skimmed thn the compression lowered back down

so if you do this how do we go about it?

as it seems your the other side of the country

i need this car back on the road... i miss it :(

BENROSS you are a legend lol

so i need to get my head skimmed thn the compression lowered back down

so if you do this how do we go about it?

as it seems your the other side of the country

pm sent

Got any photos of the gasket?

From your description you might have issues with whet it was torqued down to.

this is a good read

http://www.mlcmotorfactors.co.uk/Trouble%2...rs/GasketTT.pdf

Edited by wil_h on 23rd Apr, 2008.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph