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Discussion Starter · #1 ·
I'm thinking on replacing 79.5mm stroke crankshaft in 1.8 OHC engine with 86mm crank from 2.0 OHC in a long run. So displacement would be 1943cc instead of 1796cc. To get 8% more toque. :beer:
I've read they have the same size journals and rods. The both have "BigBlock"
http://www.imotecgmbh.de/PS-Bausatze/OPEL-OHC-Diff/hauptteil_opel-ohc-diff.html
So if std piston-top raises flat with the cylinder-block-top (deck?) at TDC, after the conversion stroke would be 86-79,5=6,5mm longer. And piston would be 6,5mm/2 over the block. That is certainly a problem.
Can i find cheaply shorter con-rods or lower pistons (pistons)?

Am I crazy?
Anyone done it? One option is also 2.2 DOCH crank /w 94.6mm.
What are the difficulties?


I'm not thinking on entire engine replacement, because i have already tuned 1.8E (about 165..185bhp, unmeasured) +1 spare.
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cam 316deg hydr, CR 12.5:1, headwork incl.bigger valves, CAI etc. (unmodified it produced 124bhp)
 

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people are giving away 2 litre 8v engines. it wouldnt be worth the effort.

the connecting rods are teh same for 2.0 and 1.8 engines, the cranks are different (as expected) and so are the block. the 2 litre will have a taller block because the piston cant, and does not stick out 6mm !
 

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Discussion Starter · #3 ·
I've heard 2.0 has 3mm taller block.
So if stroke is 6.5 longer, the piston comes 3.25mm higher and therefore must be 3.25mm lower.

Isn't there simplier conversions with DOCH crank or rods for example?

I can't understand the piston cant term!?
 

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Discussion Starter · #6 ·
tomstickland said:
Just put your head and bits onto a 2.0 block.
It would be the simpliest. Is it done before? Can you give any link to website like that (can't find anything like that in google.com)? There may be many problems to solve like:
* different combustion chamber diameter & volume (can be shaped)
* clutch (at the moment i have Kadett 1.8E flywheel, 20E clutchdisc, 18S gearbox ;) ) 18E flywheel must fit to 2.0L crank
* oilpan (1.8E part must fit)
I hope engine mountings and stuff are at the same place. They must be, otherwise it would not be "the same block", but never practiced.
I had tough time replacing 1.1S with 18E, and don't wan't to repeat that work.
I think i like this idea the most.
 

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Discussion Starter · #7 ·
0ddball said:
if the piston stuck out of the deck by 6.5mm it would stike the underside of the combustion chamber. and it would if the piston stuck out 3.5mm aswell.
That was kind of what i was asking. (if anyone knows the solution.)
* Lower pistontop
* shorter con rods
or smtg
 
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