Decomp torq settings

[jay9119]

I have a meter shop making me a decomp plate what is the ideal thickness to give me low compression, also I assume I will need custom torqe settings as it will have 2 gaskets and decomp plate to seal

[blackie_2k5]

Double head gaskets is cheaper and will be more reliable

[jay9119]

Don't I need 2 head gaskets on the decomp plate. I'm after rilibilty

[tweeqd]

ony use 1 gasket with a decomp plate

[jay9119]

Where does it go in between bottem en and decomp or at the ton between head and decomp also as for settings torqe settings and ideal thickness of decomp

[axsaxoman]

decomp plate is not needed --2 h/gaskets is cheaper and never casue problems .
and yes you are right you should have gaskets both sides of decomp plate .
the blck layer on a std h/gasket ,which is viton and that is meant to bond head +block together ,thats why your head and block should be totally dry +oil free when fitting a gasket ,
yes peple will get way with using "wellseal on one side of the decomp plate --most of the time --but its not correct
anyone using decomp plates rather than pistons is usually only running low boost ,so there is no need to drop the comp ratio to a silly low level ,it justs makes the off boost performance poor
std cars now use 10-1 and boost so if std comp is 10.6 why do you need to lower it to 8 -1 to run low boost --you don,t
use of decomp plates started because people did not want to alter ecu timing settings etc,so they could use std ecu unmodded --
with correct fuelling +timing you can run low boost at std comp ratio with no problems
lowering the comp and running high boost still doesn,t strengthen the pistons or alter their expansion rate -so it is a bodge --no other way of putting it

If someone wants low boost only I never alter comp ratio --just modify timings + fuelling to suit

[wadoryu]

Axsaxoman is giving a lot of decent honest advice lately :y:

[jay9119]

Cheers mate some sound advice there, so what you are saying if I run 2 h/g and get some one half decent to remap it I will be all good? So what torqe settings do I need? I'm in the middle of the build and will be ready to put the head on tomoz as soon as I have finished polishing the ports. Just to bra clear I have 2 h/g and 1.5mm decomp plate but I will only be using the h/g

[hazlo]

glad i read this now as ive been thinking about getting the decomp plate, Theyre dear or what they are though arent they jay? also are you keeping fully standard internals?

[markj_vtr]

I really wished I had spoken to GMC before forking out £60 on a de-comp plate.

[Ross]

Be grateful you didn't get shafted for a Dp engineering one at £250 or whatever they are nowadays.

[axsaxoman]

use std head tigtening proceedure --but after setting intial 20nm -leave for 10mins --then do them all again --then carry on with the angular torque--you can up it to 260-270 from the 240 degrees if you wish --the diesel saxo uses 270derees with same head bolts
easy to do 3 x 90,degrees ,if you don,t have the right tools .

talking of which this something i treated myself to recently to upgrade from a degree adaptor ,that needs to be held whilst you pull up the bolts .

I now jave a facom adigital angular torque device which also does normal torque settings --uses a strain gauge and a gyroscope --
ideal for single handed use in any postion

http://www.thetoolacademy.com/product_detail.asp?productId=4789

this the dogs daggles of tools

[Ross]

fucking hell John, that is posh. I like that! If I could justify it I'd get one but for the amount of times it'd get used lol...

[axsaxoman]

best tool i have bought in years --no need for someelse to hold the angle ada.
fit onto socket and any extensions on the head bar side ,so torque will be correct wind up of extrensions is not effecting torque you apply and great for doing big ends when engine in car --just tighten till it sounds like a bomb about to explode

only slight downside --when using it for angular torqueing you turn it on and wait while the gyro,s speed up --just like the inertial nav systems on your average jumbo jet,once they are going it knows how far you have turned it ,no matter what angle it is at ,so you can use it sideways ,upside down

[jay9119]

Yes mate standerd internals even tho I have had the bottem end reworked with oversized pistions but I am also going to upgrade oil pump to help and thanks for all the advise just thort with having 2 hg it will need to be tighter to get a proper seal

[vtr91]

oh balls....
im undecided wether or not to run the decomp plate i have or run 2 HG's... hmmmmmmm :/

[jay9119]

More successes running 2hg over 1 hg and decomp I have looked at leads of boosted saxo's and most seem to have problems with decomp. But you are going to run into issues ether way as ur boosting a na lump that's not ment to be so if ur no good with a spanner u better have a fat wallet...

[Ross]

Don't bother with decomp. Where does this idea even frigging come from that its needed. I'm gonna setup a website selling trousers with three leg holes. Hopefully people will buy them - after all, if I sell them, they must serve a purpose... Right? ;)

[vtr91]

lol.. what a waste of money! :P
are 2x 1.5mm mls gaskets overkill?

[jay9119]

No x2 standerd h/g and 1 unused 1.5mm decomp

[sexy_gt]

Axsaxoman is giving a lot of decent honest advice lately :y:

Priceless fountain of information :y:

[Gareth_R]

Obviously everyone's sacked off the idea of a decomp now, but just to throw my 2p in

When I did my turbo conversion I used a decomp and its fine. I also had the benefit of deciding what compression ratio I wanted, choosing ONE headgasket and then doing some maths to decide the exact thickness of decomp that I wanted. Ferriday engineering made mine and though I don't own the car anymore it is still going strong. It's also reusable.

Also, I definitely only used one headgasket. I used mine on an iron block engine with an alloy head, and the decomp was alloy. The method of fitting was block>headgasket>decomp>high temp sealant (supplied with decomp)>head. Can't speak for other retailers but certainly with mine this was the manufacturers recommendation and I'd always follow that if you want any comebacks.

2 headgaskets and a decomp would give such a piss poor compression ratio, it would be dire off boost

[vtr91]

from my research i have done, i would only be running the 1 HG with a decomp. not 2. block, HG, decomp, paste, head.

[axsaxoman]

When I did my turbo conversion I used a decomp and its fine. I also had the benefit of deciding what compression ratio I wanted, choosing ONE headgasket and then doing some maths to decide the exact thickness of decomp that I wanted. Ferriday engineering made mine and though I don't own the car anymore it is still going strong. It's also reusable.


I don,t see the problem with getting the comp ratio you want using multiple gaskets --you have four sizes to pick and mix from?--and it will always be cheaper than using a dscomp + expensive sealer with it

[hillbillyxsi]

Im planning on running a boosted 16v around 10psi. Would you say i would be ok just to use 2 h/g? I was going to buy a decomp plate but if this will be fine i will have saved abit of money :)

[Ross]

some people have been fine with it. 10psi is more than I would want to run on two head gaskets and standard internals but might be ok. Dunno how long for though.

[hillbillyxsi]

Well im just looking to break the 200bhp mark tbh dude. Ive seen people run a bar on standards with arp rod bolts as the only mod on the bottom end.

[jones91]

I've heard of people running up to 250 odd bhp on standard internals and compression before, so you should easily run 200bhp with 2 hg's and standard bottom end tbh

[axsaxoman]

head gaskets will be fine at any boost level --the weak point is use of std pistons --if fuelling + ign timing is not spot on they wil not last

[hillbillyxsi]

Sound well hopfully going to get the guys at atspeed to map it and time it up for me so should be sorted then :)

[blackie_2k5]

I was al for decomp as it being reusable should have been cheaper


But when I did try to reuse it, it never sealed properly again as it had already had 10k under its belt

Filled my rad with oil lol

IF it hadn't of done this, it would have worked out cheaper being as though I've had the head off my engine several times last year!

I just use double gasket now.. It's easier and no where near as fucking messy

[vtr91]

im going to run the decomp plate i have first, if i even need to remove the head, i will opt to run the double HG and go from there. hopefully the decomp plate will be ok.