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 Decompression Plates - Where To Get Them?  

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Phat535
  • Phat535
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  • Joined: 8-October 03
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  • From: Australia
Post #1 post 17th February 2004 - 10:41 PM
hey guys, just wondering if anyone knew any place in brisbane that makes up decompression plates?

I've called Hardcore, JHH, Bryants and tried a few small local machine shops and haven't had any luck yet
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avalonea
Post #2

well . if i was you i would get a new headgasket and take it to a engenears workshop

get them to lazer cut you a spacer up

`josh

Phat535
Post #3

I've already asked a few engineering workshops and they all said they didn't do it
even Bryants Engineering said they didn't
NiSlo
Post #4

unsure.gif Sorry to go off on a tangent, but I've seen a few posts abut decompression plates, but am cluseless as to what they do.
And also why are they used ? unsure.gif

Ichecked google, but they were just kits etc

psi999
Post #5

QUOTE (Ni-Slow @ Feb 18 2004, 05:10 PM)
unsure.gif Sorry to go off on a tangent, but I've seen a few posts abut decompression plates, but am cluseless as to what they do.
And also why are they used ? unsure.gif

Ichecked google, but they were just kits etc

Decomp plates are a very poor way of lowerering compression (For a turbo application).

In the process of lowering compression they stuff up piston to cylinder head squish thus promoting detonation (pinging).

Wonderful things they are.

Jon.
roweysvn
Post #6

Thank god u asked james cos i had no idea wat it was either


Sounds tech tongue.gif


Dave

Phat535
Post #7

QUOTE (psi999 @ Feb 18 2004, 05:35 PM)
QUOTE (Ni-Slow @ Feb 18 2004, 05:10 PM)
unsure.gif Sorry to go off on a tangent, but I've seen a few posts abut decompression plates, but am cluseless as to what they do.
And also why are they used ? unsure.gif

Ichecked google, but they were just kits etc

Decomp plates are a very poor way of lowerering compression (For a turbo application).

In the process of lowering compression they stuff up piston to cylinder head squish thus promoting detonation (pinging).

Wonderful things they are.

Jon.

don't know where I can get one made up do you? biggrin.gif

I'm quite aware of their downfalls
it's for a very cheap project I'm throwing together for a bit of cheap fun and not interested in going to the expense of fitting forgies to

OSK
Post #8

u can talk to MIKE VINE TURBOCHARGERS he has them onshelf for vl's and im sure he will tell u where u could get it done
17SLO
Post #9

if u are doing anything that required droping compression it is best to get the engine re-engineered to suit, lowering piston pin height, droping dishes, are all ways that u can do this. please go see a engine building workshop "bryants or mendham - where i work " they can help you out.

Zumo
Post #10

thats realy weird that hardcore dont do em coz they do fckn everything lol

psi999
Post #11

QUOTE (Phat535 @ Feb 18 2004, 06:26 PM)
QUOTE (psi999 @ Feb 18 2004, 05:35 PM)
QUOTE (Ni-Slow @ Feb 18 2004, 05:10 PM)
unsure.gif Sorry to go off on a tangent, but I've seen a few posts abut decompression plates, but am cluseless as to what they do.
And also why are they used ? unsure.gif

Ichecked google, but they were just kits etc

Decomp plates are a very poor way of lowerering compression (For a turbo application).

In the process of lowering compression they stuff up piston to cylinder head squish thus promoting detonation (pinging).

Wonderful things they are.

Jon.

don't know where I can get one made up do you? biggrin.gif

I'm quite aware of their downfalls
it's for a very cheap project I'm throwing together for a bit of cheap fun and not interested in going to the expense of fitting forgies to

No worries champ.

Try contacting ACL direct, I am pretty sure they make them. They are used for engines (block's) that have been decked too much in OEM engine rebuilding.... cheap as chips.

SHERIF
Post #12

mike vine at capalaba has a heap of different maodels on the shelf

Phat535
Post #13

thanks guys


.........reasonable post

Phat535
Post #14

QUOTE (Zumo @ Feb 18 2004, 07:26 PM)
thats realy weird that hardcore dont do em coz they do fckn everything lol

you'd be suprised what they don't do
I approached them about building the blown motor for my beemer and their responce was "sorry we don't touch bmw motors, we only build nissan and toyota stuff"
swoon
Post #15

Give primo automotive a go, talk to vince. They are located at 18 deshon st Wooloongabba not far from chapman and chapman, they might be able to help you out, or possibly send you the right way. I dont have the number on me.

OPM
Post #16

there is a place in melbourne that make copper head gaskets so u would be able to use one of them!!! cant think of there name so u would have to look em up..

Phat535
Post #17

they're called ridgecrest
but nah I was after a steel spacer plate, it's all good I've got one organised
thanks for the help guys

Phat535
Post #18

they're called ridgecrest
but nah I was after a steel spacer plate, it's all good I've got one organised
thanks for the help guys

Mr_Sleepy
Post #19

try leithal automotive on the gold coast , they can organise one for ya.. although i personally think you might be better off getting the pistons machined and the chambers cc'd instead. its a lot more reliable way of decompressing your engine.

thechuckster
Post #20

'tis good that you've organised steel plates - but expect to be regularly replacing blown gaskets and (before their time) pistons. Before putting the rest of your engine at risk, see if your mechanic can lower comp. ratio by machining out the head.

fwiw: my 18R turbo had it's head machined out to lower comp. to 7.4:1 . no compression plates used.

surely there's enuf meat in a bmw head to allow this?

Phat535
Post #21

haha as if I'd use a decompression plate on my bmw
as I said a few posts ago I am quite aware of the downfalls of decompression plates and it's for a cheap project that I don't really care if I blow up

a mate and I built an off road go kart fitted with a 120Y motor and 4spd manual
it has twin su carbs, large port head, large cam and the head has been shaved and the block decked for higher compression
it goes bloody well in a 400kg frame hehe

but we have decided to remove the carbs and fit a stock cam, a T25 and a draw through webber setup
hence the questions about the decompression plate

psi999
Post #22

A T25 is not going to be very successful with a suck through carby setup, it will need to be rebuilt with a Carbon seal as oil will piss out from the core when it see's vacuum, something a T25 would never see in an EFI setup.

Or you could just use a S4/5 RX7 Turbo that already have these seals from factory.

Jon.

Phat535
Post #23

the T25 I'm thinking of using has already been ran with a draw through webber attached and I'll be buying it complete with the webber and adapter plate to fit it to the turbo and the manifold

I would assume it already has the correct seals in the turbo, as it was running for quite some time with no dramas on it's old home

joker1140
Post #24

QUOTE(Phat535 @ Feb 18 2004, 06:26 PM) [snapback]4457113[/snapback]

Decomp plates are a very poor way of lowerering compression (For a turbo application).

In the process of lowering compression they stuff up piston to cylinder head squish thus promoting detonation (pinging).

Wonderful things they are.

Jon.
don't know where I can get one made up do you? biggrin.gif

I'm quite aware of their downfalls
it's for a very cheap project I'm throwing together for a bit of cheap fun and not interested in going to the expense of fitting forgies to





hey guys im currently tryin to find someone to make me a decompression plate for my subaru impreza rs ej251 coz i have a turbo kit sitting around that i was going to bolt on just to run about 6psi.. so you think decompression plates are not a good idea??? if not what are the alternatives to stop my car from going bang when i bolt on the turbo
any help would be greatly appreciated

MR2Mark
Post #25

QUOTE(17SLO @ Feb 18 2004, 07:17 PM) [snapback]4457160[/snapback]

if u are doing anything that required droping compression it is best to get the engine re-engineered to suit, lowering piston pin height, droping dishes, are all ways that u can do this.


If you are only going to run 6 psi you dont need to reduce your compression. If you get to the point where you need to reduce compression then my advice is to get the engine rebuilt to suit, probebly with forged pistons and rods of the right size to reduce compression to around 8.5/9 : 1 for turbocharged application.

mantis3dfx
Post #26

QUOTE (psi999 @ Feb 18 2004, 05:35 PM) *
Decomp plates are a very poor way of lowerering compression (For a turbo application).

In the process of lowering compression they stuff up piston to cylinder head squish thus promoting detonation (pinging).

Wonderful things they are.

Jon.


...Don't you mean "demoting" detonation?

The whole point of lowering comp in a turbo/supercharged application is to prevent the dreaded ping of death.

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