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[AndyStobbs]

It would be interesting to see a late set of slightly ported 2.5 or 2.6 heads fitted to a 3.2 as well (in order to restore the compresison ratio dropped when the 3.2/2.6 lost the EGR)

I was intending to skim the heads on the 3.2 to get upto 10.5:1 CR or there abouts. But there really isn't much scope for skimming them as I discovered when I measured up a set of y26 heads I've got here.

I felt it would be better to skim the block down.

Would deffo be the basis for a good set-up, proper CR on an engine with no EGR, tickled heads, G cams (timed up for good midrange) 3 branch ex manifolds, and a remap, cold air feed and a decent filter and it would be starting to look like decent power.

[minifreek]

I'll be going down the 3.0 cams route when I come to change the cambelt on my 2.5 next week. I have the 4 x G cams, 3.0 lower divider and a 3.0 bottom pulley to help spin the engine up a little quicker. In future I will also be installing a flywheel off a C20XE as it's a lot lighter than the OEM flywheel which is very heavy compared to the C20XE... also will be installed is a cold air feed and Courtney Sport air filter should see close to 200BHP with the change of cams and lower divider. I will also be looking at a remap later on in the year to release a few more ponies...

[Marks DTM Calib]

What you will find with the lower divider is that you get a small step on the divide/head interface, its worth spending an hour, having blocked the ports to stop debris going into the cylinder, blending the step out to much improve airflow.

On the heads, a quick calc shows a 2.5/2.6 head would raise the compression ratio of a 3.2 back upto 10.6ish:1

[AndyStobbs]

I'll be going down the 3.0 cams route when I come to change the cambelt on my 2.5 next week. I have the 4 x G cams, 3.0 lower divider and a 3.0 bottom pulley to help spin the engine up a little quicker. In future I will also be installing a flywheel off a C20XE as it's a lot lighter than the OEM flywheel which is very heavy compared to the C20XE... also will be installed is a cold air feed and Courtney Sport air filter should see close to 200BHP with the change of cams and lower divider. I will also be looking at a remap later on in the year to release a few more ponies...

In a vectra B with y26 I was seeing 211bhp with a similar spec to you. The vectra is hampered by airflow issues through the TB and plenum too.
I had 2xG, 2xA, 3.0 inlet divider, matched up the plenums (doesn't apply on the omeg), step ground out of TB (doesn't matter so much on the omeg), DE-catted y26 manifolds, and a cone filter. So with your x25 having a higher CR you should be getting good power and no cats to start with (though the ex mani's don't flow as well)

When I fitted the 4xG's my power dropped, so you need to make sure your fuelling is spot on, or you're throwing good money after bad.

On the 3.2 I'm building I have done as Mark suggests and sorted out the transition step between divider and ports. Its only really practical with the engine out though as there is little scope to do it in situ.
Interesting on the smaller heads putting the CR back where it belongs. How much difference in combustion chamber diameter is there between the smaller and larger heads?

[Phil]

any one any i deas on how i could get the most power out of my 2.5v6 omega getting the brain remapped and maby 3.0 cams but any other ways? all ideas welcome

Convert it to forced induction.

Not the easiest, cheapest, quickest, most pub chat manly way or likely to last that long but it will produce the most power.

Look at it another way.

Car value say £800 (!?!), add cost for cams, chip (custom remap?), messing about, swear box costs, replacement tubular manifolds, replacement exhaust, sports cat (or decat pipe) and you could easily spend £1500- £2k so total investment of circa £2 - 2.5k (or more) and get 200bhp - then you would look at bigger brakes, better supension etc etc etc

So sell it and buy a 3.2 - more bhp straight away in the same 'comfortable' car you are used to with minimal outlay.

Or sell it and buy a 2.8 V6 Vectra C - £2.5 - £3k and you have atleast 230bhp or 255bhp or 280bhp, either way £320 for a blue fin map and its 290ish for all 3 options, pus a considerably newer car

Or sell it and buy a 3ltr X type Jag  230bhp for around £2.5k

Or sell it and buy a V70 T5 250bhp, more with a Rica map, £2.5k etc etc etc