head gaskets, knock detection
Turbo Mini Forums

just wondering is it a good idea to use two headgaskets to lower CR ?? any known problems with doing that?

also,

how does one go about detecting knock, say in an RR session or simply while driving?

I wouldn't have thought that it's the best idea! but I've never tried it so I'd only be guessing.

Yes a RR is the best for detecting knock, as you can stand close to the engine and listen, or get a set of det cans to listen in on it.

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

http://www.mattwoodsphotography.com

what are "det cans" .. iv heard these talked about before.

slightly o/t but anyone thought about securing a pizo diafram microphone or speaker direcrtly to the block and listening to it thro an amplifier in the car? would do the same as the "screwdriver stethoscope" except you could do it while driving? can knock be heard this way? quite sure its how knock detectors work, but could be wrong!

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

knock sensors can be bought check out american racing shops's web sites , or monty turbo had a knock sensor on the block - looked like a temp sensor ,screwed in the front- maybe still buy it from rover and make your own with a light ?
on the rolling road even with all the noise pinking is easily heard , and seen as power will drop instantly

pinking is differnt to detonation thou...

one you can hear the other you cant!

alex

AlexF

I thought I read something about reducing CR by using 2 head gaskets in A.G. Bells forced induction performance tuning but can´t find it now!
Just wondering if anyone had tryed this here.

Its an awful idea...

That book is old and out of date!

Try Graham Bell's Forced Induction (I think thats the title).

Alex

AlexF

ikts an afwull idea! hasnt stopped me doing it though! not too sure how long it will last, but so long as it does a few miles, i will be a happy bunny!

And on the 7th day........... God created turbochargers!

even with two gaskets the best you'll get is an extra 2-3cc's

or to put it in CR less than 0.5:1

AlexF

the af 470 also used as a turbo head gasket has 3.8 cc in it the copper asbestoes/ steel type has 4.1 cc ,my supercharged mini was running a spacer plate to reduce compression further still, and that blew (running lean after a hose come off the inlet),quick repair at the track(goodwood) was three head gaskets to get me home , its still running at 11 psi ! its not ideal but sometimes these things work ,its been back on the rollers and is still chucking out 152 bhp @5900 rpm with these three gaskets on untill the new steel spacer plate is ready (used with an af470 either side ) its still working !!
to reduce compression exra cc's are required but how many you need is dictated by your engines size
i think pinking is detonation, pinking being the sound , detonation is the description 'the damage was caused by detonation' ?- anyone have any views ?

well if three gaskets work your nutter driver will be fine then i guess:)

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

http://www.mattwoodsphotography.com

Pinking is caused by over advanced ingnition timing, with the mixture being ignited before the piston is at TDC, they say the piston rattle sin the bore as it goes over TDC,

Knock is caused by the end gases (fuel air mixture furthest from the plug, around the ring area) in the cylinder auto-igniting, this creates a flame front which hits flame front from the spark plug, creating the knocking noise.

Detonation or pre-ignition is caused by something in the cylinder being hot enough to ignite the mitxure long before the plug should fire. This is what breaks pistons etc. Usually an incorrect grade of plug (too hot) will cause detonation.

Hope thats a help!

Stu, why use the af470, and not the bk450?

Team Racing

OK lets get a few things sorted:

Pinking, pre ignition or pinging as the American's perfer to call it is when the fuel/air mixture is ignited by somthing other than the spark plug. A glowing valve/spark plug or even part of the cylinder head (possibly a sharp beak). This can be heard easily and typicaly sounds somthing like a set of keys being jangled up and down.

Detonation is completely different. 1st you cannot hear it without Det cans, basically they are an electronic microphone that you can clip onto the engine and it filters out unwanted frequencies so that you can hear the detonation through headphones. Detonation is the uncontrolled burning of "end gasses".

The process of detonation begines with the spark plug igniting the mixture. This starts a flame which burns out from the location of the sparkpulg. As the flame front advances so the gasses behind burn, increasing both the temp and the pressure of our mixture. If this rate of burn and presure increase reaches a certain level then the gasses furthest from the plug are compressed to the point were they auto ignite instead of burning. This is more akin to an explosion than a burn.

Hence why det is damaging, the localised auto ignition is extreemly hot and very high pressure. This can be seem as pitting on the piston crown in mild form and full on melted holes in more serious cases!


Hope that clears things up.

:cool:

Alex

AlexF