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| kev87 |
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im turboing my ef and im trying to decompess it with out using a plate or getting specially ground forgies. ive been down to my local performance shop and has recommended that i hav a bit meat taken out of the pistons itself (because there only 6 months old) and to use a thicker mls headgasket. has anyone ever heard of grounding out the bowl in the tops of pistons for decompressing???
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
you'd be far better off removing metal from the chambers in the head.
you can pick a some flow while you're at it to. basic unshrouding of the valves and releaving the chamber back where it gets close to the valves wiill pick some low lift flow and lower the compression at the same time. I used to have a pic to explain what i'm talking about but i can't seem to find it. if some one has a pic of a chamber without the swirl ridged i'll draw on what i'm talking about |
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| dynowog |
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Last edited by dynowog on Mon May 21, 2007 9:22 pm, edited 1 time in total. |
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| EBXR8380 |
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Its timing control you requre, something thats boost refrenced...
http://www.msdignition.com/ignition_7_6462.htm Maybe ??? Timing is 90% the cause of detonation....
_________________ As in ZOOM 126 edition |
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| kev87 |
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yeah thanks, everyone says to take it out of the head aswell. turn it into sort of a hemisphere. dunno about the timing tho, retarding it wud lose power wudnt i (well if u dnt hav a vernier cam gear) , i'll stick with lowering the comp ratio and upping the boost, mite even get it ported a bit more while its there.
thanks lads |
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| kev87 |
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and no i dnt kno about shaving meat of pistons but the performance shop i went to which has top fuel drag cars does mate. but yeah thanks, the head is the go.
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| dynowog |
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Last edited by dynowog on Mon May 21, 2007 9:23 pm, edited 1 time in total. |
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| Delta |
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Never touch the pistons if you can help it, the head is where I've removed metal from, and DON'T use a thicker gasket unless your going copper and o-ringing, these things blow gaskets as is. If you want something that won't blow easily without going to copper and still want close to standard gasket thickness use two of the steel shim style AU gaskets, which is what I've done. My compression is around the 8.6 or 8.7:1 mark.
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| kev87 |
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hey mate i was just asking for advice. and there acl race series, not just standard pistons, which also has a thicker crown then standard. also it will hav proper egine managment! what u think im gonna run boost thru it without sum sort of aftermarket ecu attatched to it. next time can u get ur facts straight before u start hating dynowog!!!
Can anyone who is just gonna hate on ppl which hav next to f**k all advice not bother posting please. eg. dynowog |
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| dynowog |
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Last edited by dynowog on Mon May 21, 2007 9:24 pm, edited 1 time in total. |
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| kev87 |
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yeah cant b helped by ppl like you, which has no advice at all, except to b negative for no reason at all. ive done nothing to u at all mate i come to fordmods looking for advice and have ppl like u giving me a hard time. and how were u caring???? i think im a little lost here. sarcastic bullsh*t is caring???
and thats the thing mate u were no help at all. telling me to slap a turbo on a high compression engine, very smart. id like to thank everyone else who posted for there useful advice. |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
you don't need to remove that much from the chamber as to turn it into a sort of hemispherical head.
only a small amount of metal needs to be removed. But if you are getting a shop to do it they would 'CC' the chambers to get the exact size you need (though i would double check with them aswell). They should also remove the metal to the most benifit to you. eg: unshrouding the valves and laying back any chamber wall the is 'too close' to the valves (again i would double check with them on that aswell). You should also be left with a head that has no sharp edges in the chambers. the biggest problem with decking the pistons, is that you open the the squish/quench clearence (the clearence between the the piston top and the head face at TDC), that can lead to a premature onset of detonation. you should be aiming for between 35 and 45thou 35thou being ideal. |
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| kev87 |
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cool yeah. ive had it ported, but i think its just had the edges smoothed out, its not realy bigger.
thanks heaps |
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| justa6 |
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my acl's were dished out a little, the head was cc'd as well. it's running at 8:1 has been no problem so far. 350rwkw
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| ebs_4l |
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i have .135" squish clearance...
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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