paulf
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| posted on 22/3/08 at 08:09 PM |
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Zetec piston differences black and silver top.
Ive been thinking about building a turbo zetec but dont want to use a decompressio shim or buy forged pistons.I have found out the black top pistons
have a lower compression height than the silver top pistons by about 3mm, the gudgeon pin size also seems to be smaller at about 19mm instead of
20,8mm.
I am going from info i found on the web , can anyone confirm this?.
My idea is i could use black top pistons , slightly shorten the block and make some bushes and end caps to allow me to have floating gudgeon pins in
the silver top rods.
The other option is to use standard compression ratio and keep the boost to about 7 or 8 psi and see what happens.
Paul
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big_wasa
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| posted on 22/3/08 at 08:15 PM |
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another option.
There is a firm who can drop the CR by CNC porting the head.
This means if you blow the bottom end its a cheap fix.
Its the way I am looking into.
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JEPY
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| posted on 22/3/08 at 08:22 PM |
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Hi Paul,
Think the overall compression of the black top is similar to the silver top earlier versions. Although the gudgeon pin is closer to the crown of the
piston, this is compensated for with a longer conrod.
Keep your boost low, use higher octane fuel and plenty of cooling (either big intercooler or charge cooler) and you might get away with it. Or add NOS
- keep your charge temps nice and low and good power increase 
Alternatively, I'm looking to fit a rotrex supercharger and keep the boost low. Bonus with this setup is much lower heat generation than a turbo
and less likely to detonate.
J
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coozer
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| posted on 22/3/08 at 08:22 PM |
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Zetec turbo is on the carbs for me too
My plan was to use standard Vauxhall forged turbo pistons. They have a smaller, i believe, gudgeon pin diameter and are bigger than zetec ones. With a
bore out it takes the zetec to 2.1L and a low comp ratio.
I'm also under the impression the 2L head on a 1.8 gives a lower comp ratio that may be good for experimental reasons. So, at the moment I have
a spare 1.8 engine a 2L head and a Rover turbo inlet manifold.
Searching the bay for a Nissan 200 turbo to go on a Focus tubular exhaust manifold.
Steve
1972 V8 Jago
1980 Z750
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paulf
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| posted on 22/3/08 at 08:34 PM |
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I briefly considered the 2 litre head on an 1800 block but dont think it would work as you would end up with a step at the top of the bore where the
head is a larger diameter. I think this would disrupt combustion and possibly lead to preignition due to the sharp edge.
I thought the black top pistons with the silver top rods would end up 3mm lower than the silver top pistons which would lower the ratio by plenty.
I have considered the vauxhall pistons but still expensive unless used then they are an unknown .
Paul
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paulf
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| posted on 22/3/08 at 08:37 PM |
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The Subaru turbos seem ok , there are plenty available cheap on E bay from upgrades.Thats what i intend using , Madteg on here has one fitted .
Paul.
Searching the bay for a Nissan 200 turbo to go on a Focus tubular exhaust manifold.
Steve
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Schrodinger
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| posted on 22/3/08 at 08:56 PM |
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I'm sure that I've seen decompression plates for the Zetec on Ebay for use if the head has been skimmed too much or to lower the
compression if turbo ing
Don't know if they are any good though.
Keith
Aviemore
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MikeRJ
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| posted on 22/3/08 at 10:02 PM |
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quote:
Originally posted by Schrodinger
I'm sure that I've seen decompression plates for the Zetec on Ebay for use if the head has been skimmed too much or to lower the
compression if turbo ing
Don't know if they are any good though.
Decompression plates in general should be avoided, especially for turbo use.
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Dusty
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| posted on 22/3/08 at 11:09 PM |
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Another option would be to skim the top surface of the standard pistons to lower the compression ratio.
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paulf
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| posted on 23/3/08 at 04:15 PM |
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Yes have considered that, but supposedly they are weak to start with so may not be any better than leaving standard and using low boost although had
thought of machining a dish in them so leaving the outside full height to give some strength and also keeping a squish band.
Paul
quote:
Originally posted by Dusty
Another option would be to skim the top surface of the standard pistons to lower the compression ratio.
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paulf
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| posted on 23/3/08 at 04:17 PM |
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I would imagine that to do this would be expensive as you cant remove much material without altering the valve seats which would then be expensive.
Paul.
quote:
Originally posted by big_wasa
another option.
There is a firm who can drop the CR by CNC porting the head.
This means if you blow the bottom end its a cheap fix.
Its the way I am looking into.
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procomp
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| posted on 24/3/08 at 10:28 AM |
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Hi if it is of any interest to any one. Here is a LINK to a 2ltr
zetec with an Eaton M45. Some useful info on parts used for conversion.
Cheers Matt
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