car builder
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 posted on 24/5/07 at 08:30 PM |
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cosworth head.
iam running a pinto that has been board out to just over 2L, flat top pistons, been rolling roaded to 130 bhp,
Just wanted to know if i could bolt a n/a cosworth head onto it (its not a 205 block) or is it best to look for compleat engine??
and what sort for power does a n/a cosworth engine give out?
any advice welcome.
cheers,
James.
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roadrunner
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| posted on 24/5/07 at 11:25 PM |
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I thought about doing this, but the cost and work needed was way to much, i think you would have to replace those pistons as well, do what i did, sell
the pinto, use the money what you would of spent on cossie head, and go BEC, lighter and a lot faster than a pinto with cossie head. 
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nick205
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| posted on 25/5/07 at 06:29 AM |
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From what I've read (Des Hamill - How to power tune SOHC and Cosworth) the Cosworth head needs a lot of work in terms of porting and tidying up
to be any good in a n/a engine. Also standard cams and followers are designed to work with turbocharging and would need to be replaced to get the
best out of an n/a engine.
There are also issues with con rod length, piston height and compression ratios to consider.
IMO you'd be better to go for a Zetec or Duratec engine swap (or BEC if that floats your boat).
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mcerd1
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| posted on 25/5/07 at 08:01 AM |
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The pistons will need to have valve relief's for clearance and an intruder to bring up the compression ratio (as you can't skim the head
enough)
also you conrods are a major week point (carb ones worse than injection) and as the rest on the engine you'd be building would be capable of
fairly high revs there's not much point in using pinto ones
to solve these 2 problems you can get forged NA cossie pistons and a good set of std. cossie conrods - the forged pistons have the correct height for
the cossie rods (which are 1.524mm [.060"] longer than pinto ones)
I'm using cossie rods and 93mm flat top forged pistons in my 205 Pinto (the machining is being done just now) but I'm sticking to a pinto
head for now
however this gives you another problem - the cossie rods have no spray jets in them for spraying the underside of the pistons - so you'll need
one of the cossie type oil spray jets (2wd cossie used a spray bar on the pickup pipe, WRC engines used jets mounted in the block)
Des Hamill's book suggests drilling the cossie rods but I didn't fancy that, so I got a 2wd oil pump (with the bottom plate!!!!) and a
pickup (with spay bar)
I'm also using a cossie crank (9 bolts so I won't need to dowel the flywheel) and a burtons steel flywheel (so I won't need to try
and lighten a cossie one)
but this isn't really necessary
The forged pistons cost ~£500, the crank ~£200, conrods ~£60, pickup pipe and oil pump (new from cosworth) ~£200, steel flywheel ~£200, ARP bolts (big
end and flywheel) ~£110
Add to that all the normal rebuild parts and machining and a full balance ~£1000
and maybe another £500-800 for your head work + 2 cams, 2 adjustable pulleys, a cossie crank cambelt pulley, cossie aux. shaft pulley, cossie cam
belt, new inlet and exhaust manifolds - and I've possibly forgotten a few things
and if your still thinking about this - is it worth doing it to a 20 block ?? my feeling is if your going to do it you might as well do it to a 205 or
200 [cossie 4x4] block
And if you do all this you'll basicaly have a complete NA cossie engine capable of maybe 9000+ rpm and more than 200bhp if everything is right -
but there are cheeper/ easier ways to get this kind of power or more
https://www.burtonpower.com/default.aspx
http://www.grahamgoode.com/cosworth/ sell alot more than is on there website
-Robert
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