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dlittlelion
Riding Shotgun
Joined: 08 Nov 2005
Posts: 451
Location: East South East
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 Posted: Tue Jul 25, 2006 10:27 am Post subject: |
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i'm using a decompression plate to lower compression
I purchased a 1.2 mm decom plate
Decompression Plates.
The difference between a Decompression Plate and a Solid Copper Head Gasket � is very little. These two items are essentially the same (i.e. a metal version of the original head gasket), although the solid copper head gasket has extra locating holes machined for Ferriday Sealing Rings. A solid copper head gasket is needed when a conventional head gasket is not strong enough for the amount of power a modified engine can produce. A decompression plate is used as well as the conventional gasket to reduce compression ratio, or restore piston to valve clearance on heads that have been heavily skimmed. A copper decomp plate simply becomes an extension of the block, and allows the head gasket to do its job in the normal manner. Decomp plates can also be made from aluminium alloy, should be placed next to the aluminium head (2 similar materials together to become an extension of the alloy combustion chamber). Ferriday Sealing Rings are not needed with decomp plates.
When using a Decompression (Spacer) Plate - only one head gasket must be used � the clamping forces that are generated by the head gasket are transmitted through the plate to help sealing at the metal-to-metal joint. All that is needed to seal the copper plate against the block is a thin smear of high temperature non-setting sealant around the water & oil galleries between the 2 metal surfaces only. Let the conventional head gasket do its job in exactly the same way as if the spacer plate wasn�t there. Don�t forget that with OHC engines it may be necessary to use a vernier pulley to allow correct cam timing settings. It is not necessary to anneal a copper decomp plate.
Aluminium-alloy or Copper? � If your engine has an aluminium cylinder head then the decompression plate can also be made from aluminium alloy. In this case the plate should be placed next to the aluminium head, so effectively becoming an extension of the alloy combustion chamber.
Customers often ask whether an aluminium decompression plate is strong enough - both your pistons & cylinder head are made of aluminium alloy and perform their separate tasks without problems during normal engine running. An alloy decomp plate will also perform well under normal conditions. If an overheat occurs (localized or general) then all these components are in danger of destruction, but it is quite conceivable that the plate may fail before the pistons. This should be regarded as a good thing as it is easier & cheaper to replace than the pistons! |
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dlittlelion
Riding Shotgun
Joined: 08 Nov 2005
Posts: 451
Location: East South East
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| Posted: Fri Aug 11, 2006 10:27 am Post subject: |
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| Ok Guys i had a small fire due to the use of an impropper oil line to the turbo i'll post som pix later |
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Plex
Zorce Jedi Master
Joined: 01 May 2005
Posts: 9039
Location: T&T
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| Posted: Fri Aug 11, 2006 10:50 am Post subject: |
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| hope everything is ok and u could still continue with the project. |
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smokes
Pumpum Conqueror
Joined: 15 Sep 2006
Posts: 7
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| Posted: Fri Sep 15, 2006 2:33 pm Post subject: |
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right i've taken tu engine apart the stock internals are very well balanced from start. conrods crank and pistons are with in close tolerances. Turobo in it you will need to increase the vavle over lap to take advantage of the turbo pressure to force the exhaust gases out faster. reduce the compression ratio by fitting two gasket to raise the cylinder head as runing standard compression ratio thing will be liable to go bang.
Fit new bearing to the crank and the conrods a high pressure oil pump and water cooler. |
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LionTamer
Zorce Moderator
Joined: 02 Nov 2005
Posts: 238
Location: Valsayn
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| Posted: Sat Sep 16, 2006 7:51 pm Post subject: |
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| what the hell are u talking about bro? |
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dlittlelion
Riding Shotgun
Joined: 08 Nov 2005
Posts: 451
Location: East South East
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| Posted: Mon Sep 18, 2006 7:48 am Post subject: |
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| smokes wrote: | | you will need to increase the vavle over lap to take advantage of the turbo pressure to force the exhaust gases out faster. |
eah?????
Over lap and turbo is like oil and water 99.99999999% of turbo cams have little or no overlap.... with forceed induction yuh dont need to use the low pressure caused by the verlocity of the exiting exhaust to draft in intake air like NA engines A typical turbo cam has very little or if possible no overlap with marginal duration
have a read
Duration:
Duration is critical to a turbo setup since its probably the single most important event of a turbo motor (i.e. time valve sits open and closed). Since the air is being forced instead of drawn into and out of the combustion chamber, duration will be your largest variable on how that incoming/outgoing air is managed.
Duration when using a manifold or log design on most turbo cams is usually about 6 degrees more intake duration than exhaust duration (226/220, 240/234). This is mainly because a manifold/log design will typically see higher then a 2:1 pressure ratio in the exhaust ( as high as 4:1 with some logs). By using a reverse split duration this will somewhat help prevent from getting exhaust gas reversion.
Duration when using an efficient header setup with most turbo cams will usually be (230/230, 224/224) or better known as a dual pattern cam. The thinking is with the exhaust backpressure being only 2:1 you can leave the exhaust valve open a little longer then if the exhaust backpressure was 3:1 or higher. Also some of the new turbo designs produce a much lower backpressure with the advent of better flowing turbine wheels and housings which further decrease the total amount of backpressure created by the system.
Overlap:
Overlap definition, is the time period when both the exhaust valve and the intake valve are open at the same time. The exhaust valve needs to stay open after the piston passes TDC in order to use the vacuum created of the exiting exhaust gases to maximize the amount of exhaust gas drawn out of the cylinder. The intake valve opens before TDC in order to use the vacuum created by the exiting exhaust gases to start drawing the intake charge into the cylinder.
This sequence of events above are controlled by the duration and LS (Lobe separation) of the cam. On a typical N/A motor this is essential since you have no pressure being developed on the intake side to push the charge into the combustion chamber. The problem with this event is a turbocharged motor will create a larger amount of backpressure on the exhaust side. Due to this event the above definition will not apply. Reason being is, when the intake valve opens at BTDC, the burned gasses in the chamber will exit out the intake since the pressure is lower than the exhaust. Since this is true you would not want to open the intake valve until the piston has started going down, ATDC. This will lower the combustion chamber pressure till it's below the intake manifold pressure |
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LionTamer
Zorce Moderator
Joined: 02 Nov 2005
Posts: 238
Location: Valsayn
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| Posted: Mon Sep 18, 2006 2:05 pm Post subject: |
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| thank u David i thought i was going mad...i was now going & scrap my motor...... |
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NarendZORCE
Zorce Editor-in-Chief
Joined: 04 Apr 2005
Posts: 3137
Location: In Zorce, usually after the contents page
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| Posted: Mon Nov 06, 2006 10:59 am Post subject: |
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Can your 1.8 bottom end work in this project?
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LionTamer
Zorce Moderator
Joined: 02 Nov 2005
Posts: 238
Location: Valsayn
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| Posted: Mon Nov 06, 2006 11:43 am Post subject: |
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| i have actually given David first preference on this but i think he has his hands full right about now with a new baby..other than the car...i am not extremely familiar with the 1.6 so i dont know....but i can find out quite easily & make a post so maybe someone can do a similar build with a 1.6 head & 1.8 bottom end. |
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Plex
Zorce Jedi Master
Joined: 01 May 2005
Posts: 9039
Location: T&T
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| Posted: Mon Nov 06, 2006 1:22 pm Post subject: |
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interesting, i know the 1.6 is a TU engine whereas the 1.8 is XU engine correct me here, can it really work?...your price for the bottom end is very attractive and i did the maths, but bad timing for me if i wanted to buy it as this would have suit my engine perfect..perhaps funds will be better for me next yr..  |
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LionTamer
Zorce Moderator
Joined: 02 Nov 2005
Posts: 238
Location: Valsayn
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| Posted: Fri Nov 10, 2006 8:23 am Post subject: |
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| well i have no real buyers as yet......it will not work with the 1.6 head.....i imagine i will have to keep this bottom end for a little while as other pug tuners has not gone to this extent as yet....so plex maybe u may end up with it anyway.....glad u did the maths & realise that what i am offering is a really excellent deal for any 1.8 owner wanting to eventually go with boost. |
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Plex
Zorce Jedi Master
Joined: 01 May 2005
Posts: 9039
Location: T&T
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| Posted: Fri Nov 10, 2006 9:00 am Post subject: |
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| that would be cool... |
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dlittlelion
Riding Shotgun
Joined: 08 Nov 2005
Posts: 451
Location: East South East
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| Posted: Wed Dec 13, 2006 10:03 am Post subject: |
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yeh fellers............ah update de car up and runnin but i have some cooling issues i reduce the piping size to 2 inch and reorient the turbo compressor so that the piping runs over the tappit pan cover the total length of the piping including bends is 3 1/2 feet......very quick hard hitting boost (13psi) the clutch gone it dead dead dead the release bearing singing like ah semp and meh velocity joint knocking like nobody home..The next plan is to pull down the front and replace the radiator and the fans.... I have to make a trade off and stick to the stock clutch to protect the more expensive parts like the axles and gear box but dem upgrades comming next year.........in the mean time i'm lookin to pimp out my 405.
********IF YOU ARE THINKING OF CHARGING YOUR PUG DONT************
***********JUST DO IT!  ************************ |
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Plex
Zorce Jedi Master
Joined: 01 May 2005
Posts: 9039
Location: T&T
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| Posted: Wed Dec 13, 2006 10:22 am Post subject: |
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| U want to pimp the 405...slap some 18" ...check my the mad pug thread i posted some smooth 405... |
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chinee
Jedi Hopeful
Joined: 26 Feb 2006
Posts: 229
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| Posted: Wed Dec 13, 2006 10:55 pm Post subject: |
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actually i WILL definatley charge my pug via supercharging or turbo...when it running i will decide...  |
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