Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: husky12 on 08 January 2014, 03:04:20

Title: how to get most power out of 2.5v6
Post by: husky12 on 08 January 2014, 03:04:20
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 
Title: Re: how to get most power out of 2.5v6
Post by: Dan282 on 08 January 2014, 06:42:28
Cams and a chipped ecu are a good start. Weight reduced, limited slip diff, exhaust maybe?
Title: Re: how to get most power out of 2.5v6
Post by: kcl on 08 January 2014, 07:11:27
How much easier it would be to put 3,0 engine in, achieve same results and save a lot of money... With 3,0 cams and chipped ecu you will not get even near to +10% power. I'd say +10 horsepower max. 3,0 engine has got more.
Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 08 January 2014, 08:27:24
3.0 cams plus inlet divider will see circa 18-20 bhp gains (3.0 cams have higher lift), if going further then 3.2/2.6 manifolds are much improved over the cast items on 2.5/3.0
Title: Re: how to get most power out of 2.5v6
Post by: kcl on 08 January 2014, 08:45:39
3.0 cams plus inlet divider will see circa 18-20 bhp gains (3.0 cams have higher lift), if going further then 3.2/2.6 manifolds are much improved over the cast items on 2.5/3.0

Yes, but putting a whole 3,0 lump in will give the same/even better result and seems that these engines are available for less than 100 pounds so I'd be tempted to change the whole lot.. and then, if needed, putting the chipped ecu to that setup. And still the car will never ever be significantly quicker, nor it will become a sports car.
Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 08 January 2014, 09:16:17
A 3.0 transplant is an alernative (Although the query was how to get more go out of a 2.5), going 3.0 then the better manifolds are also an option
Title: Re: how to get most power out of 2.5v6
Post by: chrisgixer on 08 January 2014, 09:41:11
3.0 cams plus inlet divider will see circa 18-20 bhp gains (3.0 cams have higher lift), if going further then 3.2/2.6 manifolds are much improved over the cast items on 2.5/3.0

Superior, see. ;) ;D

Are 3.2 cams no use btw ? Just wondered, in case they come up before 3.0 cams, for the op.
Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 08 January 2014, 10:20:09
Unproven would be a better phrase, given the 2.6/3.2 have poorer eonomy than th 2.5/3.0 then I would be going for the earlier setup (plus there should be more about of the 3.0 ones)
Title: Re: how to get most power out of 2.5v6
Post by: AndyStobbs on 08 January 2014, 10:38:16
J shafts seem to be half way between A and G from what I quickly observed on mine.

Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 08 January 2014, 10:57:19
Interesting as I have never had an opportunity to measure the lift or duration on a set of J's.
Title: Re: how to get most power out of 2.5v6
Post by: tigers_gonads on 08 January 2014, 12:34:03
Out of interest, has anybody dropped a set of G cams off a 3ltr in a 3.2 ?
Replacing either inlet, exhaust or maybe both ?

I just happen to have a set off my 3lt cams sat here and the cam covers / timing belt just happen to be on the agenda  this year  :)
Title: Re: how to get most power out of 2.5v6
Post by: AndyStobbs on 08 January 2014, 12:49:55
Out of interest, has anybody dropped a set of G cams off a 3ltr in a 3.2 ?
Replacing either inlet, exhaust or maybe both ?

I just happen to have a set off my 3lt cams sat here and the cam covers / timing belt just happen to be on the agenda  this year  :)

About to do just that. Haven't fired it up yet but that's the spec I'm building my 3.2 to. Removed the J pair and replaced with G. Giving 4xG
Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 08 January 2014, 13:12:21
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)
Title: Re: how to get most power out of 2.5v6
Post by: husky12 on 08 January 2014, 13:50:54
3.0 heart is next plan of action wen this engine blows, wat wud all need to be changed? and 3.0 engines arnt that easy come buy in northern ireland and arnt that cheap, unless any one knows of one?/ also in the post i put 2.5 i keep for getting the engine is 2.6 block, head nd cams running 2.5 gear.
thanks for all help
Title: Re: how to get most power out of 2.5v6
Post by: tigers_gonads on 08 January 2014, 14:17:44
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)


What was Daz doing to that engine he has  :-\
Title: Re: how to get most power out of 2.5v6
Post by: AndyStobbs on 08 January 2014, 14:24:07
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.
Title: Re: how to get most power out of 2.5v6
Post by: minifreek on 09 January 2014, 08:02:32
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...
Title: Re: how to get most power out of 2.5v6
Post by: Marks DTM Calib on 09 January 2014, 08:12:01
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
Title: Re: how to get most power out of 2.5v6
Post by: AndyStobbs on 09 January 2014, 08:47:32
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?
Title: Re: how to get most power out of 2.5v6
Post by: Phil on 09 January 2014, 09:26:35
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  :)