Personally I would never use a de-comp plate

Edited 23 September, 200817 yr by G40NUT

Personally I wouold never use a de-comp plate

...Your reasons?

If you are going to buy pistons anyway, chose pistons that are have the correct CR for your application.

De-comp plate and twin headgaskets are a bit ghetto to me

Rather than using a de-comp plate to drop from 9:1 to 8.5:1 wouldn't it be simpler to use the mk4 letal gasket to take the 8:1 to 8.3:1 (assuming it's a roughly accurate increase), probably quite a bit cheaper.

^^ not too sure what you're trying to say there Depresion. He already has accralite pistons which increase the CR to 9:1, fitting the metal HG which is thinner will increase it more!

This is my problem you see guys... I have already got the Accralites and my bottom end is fully built cos i was under the impression that i would have a safe CR with a thick metal head gasket (which doesnt exist) so for me the options are limited. I'm not going to buy the Wossners, pull my bottom end apart and rebuild it. I think I'm going to have to get a De-comp plate - just wanna know that they are gonna be safe enough to use under high boost - time for some research!

Some times i feel like jacking this f**king thing in - ahhh!!

BUT IT WILL NEVER BEAT ME!!!

why don't you just use the accralite pistons with a normal g40 gasket? lots of 1341 conversions exist with this setup. Might not be as ideal as the wossner pistons but short of throwing a load more money at it you're pretty stuck now. I'd have thought slightly higher CR would be better than a de-compression plate & two headgaskets. Just run a touch less boost but enjoy better off-boost performance, Make sure you always use high octane fuel, maybe even aquamist with a methanol mix too to add knock resistance

Personally i cant see any problem with a de-compression plate. They seem to be well designed and manufactured pieces of kit that do exactly what they say on the tin.

There was an article in PPC a couple of years ago with the step by step build progress of a turbocharged Ford Capri engine. The guy used a de-comp plate from Ferriday Engineering and commented on how well manufactured it was. Apparently you'll need to give them all the details of your engine (bore/ stroke/ desired C.R etc) and they do all the calculations for you.

It's a properly designed boosted engine, using a decomp. plate is just Irish. If you want low compression then buy suitable pistons.

It's a properly designed boosted engine, using a decomp. plate is just Irish. If you want low compression then buy suitable pistons.

With the choice of pistons - yes i agree but as you have probably read, it is a bit too late without a full strip/more money/rebuild.

I am clearly trying to avoid having to strip/re-build the ALREADY built Accralite 1341 i have, so therefore if a de-comp plate is cost effective and a safe method of achieving a lower (safer) CR as replacing the pistons then it can be as IRISH as it likes... plus the 'properly designed' engine wasnt built to withstand high power increases etc etc however boosted or designed!!

Personally i cant see any problem with a de-compression plate. They seem to be well designed and manufactured pieces of kit that do exactly what they say on the tin.

There was an article in PPC a couple of years ago with the step by step build progress of a turbocharged Ford Capri engine. The guy used a de-comp plate from Ferriday Engineering and commented on how well manufactured it was. Apparently you'll need to give them all the details of your engine (bore/ stroke/ desired C.R etc) and they do all the calculations for you.

You seem to be quite right!! Alot of the ford guys run de-comp plates and they never let go apparently. Ferriday appear to have a good reputation and as you say they will sort out all the math for you if you give them the required details.

I'm gonna ring them tomoz and ask a few Q's..

why don't you just use the accralite pistons with a normal g40 gasket? lots of 1341 conversions exist with this setup. Might not be as ideal as the wossner pistons but short of throwing a load more money at it you're pretty stuck now. I'd have thought slightly higher CR would be better than a de-compression plate & two headgaskets. Just run a touch less boost but enjoy better off-boost performance, Make sure you always use high octane fuel, maybe even aquamist with a methanol mix too to add knock resistance

All the things you say make sense but i wanna have a CR i trust and one thats gonna take some boost abuse if/when needed. I intended to run on good fuel and possibly look into fuel additives as well... not sure which road to take atm but i am fed up with choosing the wrong one so its some carefull consideration this time rather than just jumping in like i usually do lol..

This is why i'm asking for the help and advise...

All the things you say make sense but i wanna have a CR i trust and one thats gonna take some boost abuse if/when needed. I intended to run on good fuel and possibly look into fuel additives as well... not sure which road to take atm but i am fed up with choosing the wrong one so its some carefull consideration this time rather than just jumping in like i usually do lol..

This is why i'm asking for the help and advise...

It will take some boost and abuse, no problem there. It is only that some of the 1341's could do with slightly lower CR. To find out, you have to build yours . There's a lot of other variables that comes to play too. Like turbo/charger size, boost, inlet temps (intercooler), cams and headwork (flow)

Edited 26 September, 200817 yr by G40NUT

people put de-comp plates in when they can't or don't want to buy the proper pistons, it's a work-around at best. You've already got the pistons so putting a de-comp plate in too is crazy if you ask me. The majority of 1341cc G40s in the UK have accralite pistons with increased CR to about 9:1 and are generally fine. If you are adamant about using a de-comp plate then do it but in my eyes it's the wrong thing to do. No matter how well made the plate is, you have to run two headgaskets etc... more points of weakness in the cylinder... If you have issues generally caused by too high CR then there are better ways around it, less ignition advance, better fuel, fuel additives, water/methanol injection....

Thanks for your input guys it is appreciated..

I'd just run with what you've got Jez. If I ever have to build another engine I won't be using the Accralites, but for the time being I'm stuck with them. Lots of the PSD cams for 1341cc motors have lots of overlap, you'd achieve the same thing with a more 'normal' cam and lower compression, but that's the way Steve and Liam did things.