Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: ngrainqey on 23 December 2008, 23:20:59

Title: y26 and x25 engines...
Post by: ngrainqey on 23 December 2008, 23:20:59
are they both mechanically the same so i can just swap the heads over straight from an x25?
afaik it's only really the ancillaries that are different? i.e the block and heads are the same with coil per cylinder instead of a dispack?
thanks
Title: Re: y26 and x25 engines...
Post by: Kevin Wood on 23 December 2008, 23:35:52
A good comparison of the main engine parameters here: http://www.club-opel.com/engines_list.php?lang=eng

The bore is slightly larger on the 2.6 to take the capacity up. Depending on how the combustion chamber is made up that might mean you get a little more compression with 2.5 heads but it won't be excessive. You may find that the mountings for the coil-per-plug coil packs are missing and you'll probably want to use the 2.6 cam covers for the same reason.

Kevin
Title: Re: y26 and x25 engines...
Post by: ngrainqey on 24 December 2008, 00:47:20
ok thanks kevin,
whats keeping you up so late lol?
Title: Re: y26 and x25 engines...
Post by: Kevin Wood on 24 December 2008, 01:04:41
Well, my PC clock says it's 23:31. Must re-set that.

Been off work since Thursday burning up annual leave so have slipped into my natural body clock function. ::)

Kevin
Title: Re: y26 and x25 engines...
Post by: ngrainqey on 24 December 2008, 01:08:15
lol!
mine says 1:07 so really must go dive into bed!
alex
Title: Re: y26 and x25 engines...
Post by: ngrainqey on 24 December 2008, 01:10:56
also, about raising the compression ratio.. it should only be to around 10.8:1 shouldnt it?
thanks
alex
Title: Re: y26 and x25 engines...
Post by: Kevin Wood on 24 December 2008, 14:21:45
Quote
also, about raising the compression ratio.. it should only be to around 10.8:1 shouldnt it?
thanks
alex

It might be a shade more. 2.6 has a slightly higher swept volume so if the combustion chamber size stays the same it will give you a little more compression.

Handy calculator here: http://www.csgnetwork.com/compcalc.html

Plug in the parameters for the x25xe (81.6x79.6, 10.8:1) and calculate the combustion chamber volume, then change the bore to the y26se's bore (83.2) and calculate the new compression. I got 11.17:1. Not a crazy level, but quite high. I would say super unleaded (or LPG) would be a good plan at that level. Might get a bit more power, of course.

Having said this, if the pistons are different (e.g. one has a dished crown to form a combustion chamber, and one doesn't) the calculation will be to pot. We have assumed the combustion chamber volume is all in the head.

Kevin
Title: Re: y26 and x25 engines...
Post by: ngrainqey on 24 December 2008, 14:34:08
okay kevin ;)
more power is good! plus it's cheaper because i have two heads on a spare x25 in the garage hehe!