Decompression plate

[focrs]

Is there a decompression plate available for the 182? I am going to be looking into getting a supercharger and I have seen decompression plates use on zetec engines for similar chargers and turbos but I have not seen any for the clio. I know these are not ideal but will maybe help untill I get a bottom end fully sorted.
Any info would be great.

 

[Chip-mk1]

MWMsport do a 3mm cometic gasket, this drops the CR down to low 9s IIRC.

Be careful though as you can run into issues with the belt wrap if you dont know what you are doing and ending up with it not tensioning correctly.

 

[jjones82]

Not 100% sure about decompression plates, thought i saw one on ebay a year or so ago.
But i know engine dynamics do a thicker layered head gasket that reduces the compression a bit (Not sure what too though sorry) as they use them in their turbo conversions.

 

[batesey]

I say put a clio 197 head or get your current head machined mate

 

[Chip-mk1]

197 head works well on mine to lower the CR, I dont have the exact numbers though as it wasnt me who did it.

 

[geznay]

Had a decomp plate on a 106 gti that i turbocharged few years back. Its ok if not on boost all time but i used it for track use and due to the engine temps couldnt get it to stay sealed properly between block and plate as only gasket between head and plate. Id save yourself the hassle and just wait to get forged pistons.

 

[focrs]

Are the 197 heads a direct fit and is there any other parts needing to replaced with that conversion. What belt would you be running with 197 or 182.
I was thinking the decompression plate realy to keep the cost down to get the car built up quick then get a forged bottom end in the future but if a 197 could be more cost effective I would go with that.

 

[geznay]

But for the money you will pay for a 197 cylinder head could mostly pay for forged pistons?

 

[Chip-mk1]

Thick gasket is by far the cheapest option.

 

[focrs]

The plate/ gasket dose look the better option in the short term to get the parts together and get it all up and running.

Does the 197 head have any other benifits has it got bigger valves? Better flow ?

 

[Chip-mk1]

197 head has better inlet ports, but thats of no real consequence TBH.

Chamber shape is slightly different, but again not in anyway that would matter.

The inlet is far better for a turbo though, cause you can get at the plugs with it in place!

 

[focrs]

I will be going with a custom inlet on my car to keep the pipe work shorter.

 

[Chip-mk1]

I will be going with a custom inlet on my car to keep the pipe work shorter.

Shorter pipework (depsite what seems logical) isnt going to make any significant difference in spool or performance IME, but it will look neater, so depends why you want it shorter?

 

[focrs]

Agreed there will be Next to no Improvement if it's supercharged but if it was a turbo there would.

I just don't like a lot of pipe work if it can be done neater and I like to make my car my own.

 

[Chip-mk1]

Agreed there will be Next to no Improvement if it's supercharged but if it was a turbo there would.

Even for a turbo mate, it makes no difference you would notice.

I understand why you would think it might, but having tried it, it just doesnt.

Bottom line is even 10 litres of air is only 5 revolutions of the engine, which at 3000rpm, is only a tenth of a second, and its not even the case that you have to fully filly those 10 litres with pressure before it starts making it out the other end, so its more like hundredths of a second and hence you cant even tell.

I was of the same mistaken belief as you till I tested it.

I just don't like a lot of pipe work if it can be done neater and I like to make my car my own.

Agreed, neater is better



You could try an inlet like the one I have made for the temporary engine Ive just put in my Mk1 project (will be a honda lump but for now is just a cammed williams one)

 

[focrs]

Looks good is that off a gtir ? I have one in the pipeline for my car just now will add a picture if my works computer allows me as I a stuck here for another 6 days.

 

[Chip-mk1]

Yeah its a pulsar plenum that I adapted to fit.

This is what it looks like minus the plenum cover:

 

[focrs]

That looks excellent did you make both parts? I take it you will be running a smaller radiator with that.

 

[Chip-mk1]

I cant still run the fullsize rad and it will clear, but im using a polo one that I had from when it was on bodies previously anyway.

Its a pulsar plenum, an ITB manifold, and then an adaptor plate I made and a spacer that a friend got made, and then I added 4 trumpets to smooth the flow.