Spacer plates & Headgaskets
Turbo Mini Forums

Ok , Please what are your thoughts? Im sorry if this has been covered be fore :-

My engine was built using 2xheadgaskets and seems to be ok .
I have used ARP studs etc and have even compression in all four bores.
I used this method to lower the compression (short term fix)and now i`m thinking of using a sandwich plate to decrease compression even more.

Has any one else done this and what boost did they run.Any info would be good.

Thanks John

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

surley there must be a better way, what is the spec on the rest of the engine, and what CR are you aiming for?

Team Racing

Spacer plates?

why bother when you easily dish the pistons to get the desired results.

Think of all the pi$$ing about getting the rocker geometry correct.

JF.

Thanks for the replys.

The engine is bored 20 thou over with Heplite pistons,7cc or 11cc dish i think .Usual balancing etc .276 cam.
At the moment im using a metro 1275 hle auto head with some seriously big valves.
Can`t remember the size but were alot bigger on inlet than std turbo .Bronze guides as std etc .so with this in mind i used 2x std turbo head gaskets , fitted head with 1.5 roller rockers and i have had no problems as such .
Money not plentiful so i thought i`d try it ,till i can get a full blown turbo head.
Engine running with front rad , intercooler and at moment ,while running in 3-4psi.
Just wondered if any one had played with this before ?
John.

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

Ok some more thoughts on this, for reasons of why.......For the drag set up , lower compression, more boost so it all comes in at certain revs ,bearing in mind cam and piston dish etc.
But changing heads or compression ratio by spacer plate etc and using different rocker ratio`s you can alter the cam profile or lift as well .Right !
So its a nother way of changing the state of the engine.


So when racing at the strip lower compression , change power band etc
And then using car for work etc raise the compression etc so it is more driver-able.

Please your thoughts.....
John.

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

Bodging!

Rubbish combustion due to no squish, will be crap reliable when you crank the boost up. Rocker geomtery is crap unless you got some special long push rods etc...

Of course you got get a billet cam ground with extra large diameter lobes, but the cost...

Do it properly!

surely itll be cheaper to get a head than have a decompression plate made up, then later chuck the plate away and buy a head

why do you need less cr to what you currently have?

just wait and get a head, or have your one done by someone like benross, he will do a decent job at a decent price

otherwise things will be horrid and take loads more time and money to sort things like geometry etc

I`m puzzled by your answers.

One minute you talk of experimenting and trying different things ,eg cams ,turbos etc,

the next you call it bodging.Vegard what can i say....

Developement is through trial and error.Just to see what happens if.......
If you never try , you`ll never know.
Thanks for the replys .

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

It may also be worth noting that de - beaking the combustion chamber is also necessary once you get to a certain boost level, to remove the hot spot, which may give you detonation...incidently this lowers the cr too

Guys, your opinions...what sort of level would you need to do this ?

Cheers

Brocky

Edited by Brocky on 15th Mar, 2006.

BTW - I took my buddy VTEC Pete out for a spin this weekend, and even though I am running her in, he gave it a name, the "Brocket"...cause I'm a brocket maaannn, nah nah nah nah nah nah nah nah nah nah nah....

Build thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7483

Katy Mini Owners Club Thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=505552

Let's make sure you embarrass at least one VTEC MINI today !

https://www.facebook.com/groups/17557298589...096464253807802

Good question, brocky.
I believe that the beak is there to help/produce swirl affect for the mixture in the combustion chamber on N/A engines,for an even burn.

So with that in mind when you start to use forced in duction under pressure the swirl affect is not so important, for even burning ,mixing etc.Its just pushed in there....

The std Metro turbo head had the beak and could handle 3-7psi from factory, so i would assume after this you would start to think about removing it .Like you said a possible hot spot.
So around 10psi ....
Im taking mine to 10psi with the beak and then on to 15psi so we will see.The head is not a turbo head .It has been ported , and has big valves,bit like the 60`s cooper s which is why i needed ,after fitting the pistons to get the CR down.Thus 2xhead gaskets or spacer plate .

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

Ok now i understand where you are coming from.But if the plate is identical to the headgasket shape ,why would you have detonation?
are you thinking of the thin metal exposed to high temp?

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

So what your sayingis that there is an optimum valve sizes to use on the a series turbo engines,is that it?

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.

My way of thinking was to increase the inlet valve size , keep the exhaust the same as std .
Keep the beak to help with the swirl in the combustion chamber and the using a std cc dished piston use a head with certain sized valves and slowly raise boost with different Cr thus the gaskets and plate.
Ido appreciate what your saying and very interested in your comments.
John

I know , i know im sorry , it just makes me grin !!!

Intercooled 1293 cc Turbo +
March 06,4psi and counting .
Its now gone up to 8psi.
Nov 06,10psi +.
And now part of the Airbourne club.