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[BigDov]

HI guys/gals.

As some know recently picked up a 2.5 v6 estate and well, it could be doing with a little help under the bonnet power wise .

Been doing some digging and picked up a few bits and pieces to get me started but obv don't really under stand how to actually get the best from the engine, already got a set of G and A cams bought for the car which seem to be the recommended combination.

Read posts about the 3.0 lower plenum, guessing that's the black bit that sits just above the intakes to the heads?

Any other bolt on engine bits that would be recommended such as the 3.0 throttle bodies etc ect?

any help or pointers for parts/ upgrades would be greatly appreciated.

[106pete]

What year is it? There may or may not be a mantzel type power box forsale on a well known auction site for the early style inlet set up. Or am I not allowed to say that?

[deviator]

££ for ££ an engine swap is the best way in my opinion. My 3.2 engine cost me £300 with 50k on it. Granted I need to throw about another £200 at it in gaskets, cambelt & water pump. That should give about 30bhp more than 2.5 (I can't remember all the exact engine size -v- cam = what bhp).

[BigDov]

What year is it? There may or may not be a mantzel type power box forsale on a well known auction site for the early style inlet set up. Or am I not allowed to say that?

It's a 1996 omega, what's the power box?

May look into an engine swap in the future but not sure how it will work as the cars not drive by wire so may have to have to be the 3.0 for simplicity.

[deviator]

What year is it? There may or may not be a mantzel type power box forsale on a well known auction site for the early style inlet set up. Or am I not allowed to say that?

It's a 1996 omega, what's the power box?

May look into an engine swap in the future but not sure how it will work as the cars not drive by wire so may have to have to be the 3.0 for simplicity.

It's not an issue, the FBW that is. You strip the doner engine down the bare block and heads (assuming it hasn't come from an Omega already). You use your original throttle body, plenum and accelerator cable. I really is as easy as swapping it for another 2.5.

[BigDov]

Hrm, didn't think you'd be able to do that, that opens up many possibilities

[zirk]

What year is it? There may or may not be a mantzel type power box forsale on a well known auction site for the early style inlet set up. Or am I not allowed to say that?

It's a 1996 omega, what's the power box?

May look into an engine swap in the future but not sure how it will work as the cars not drive by wire so may have to have to be the 3.0 for simplicity.

You could add a Re Chip to the list, fairly easy to fit, worth fitting on the 2.5 and 3.0 in my book as worst case without doing other mods they do improve economy.

Should have some more Chip Remaps coming in soon for the 2.5, 3.0's if your interested.

The Mantzel boxes don't really do much on there own, if anything can make it worse. There designed to enhance Air Flows inlet resonance at full chat with other engine mods for high RPM and HP for Race / Track mode. The Box does away with the Multi Rams so for normal day to day driving mode you will lose low to mid torque and poorer MPG.

[Diamond Black Geezer]

Yup, the usual thought process whenever more power from the V6s follows this common theme...

"Oooh, look at all that stuff on the front of the engine... hmm, I've heard stuff in the pub, and reckon after my five minute chat to a mechanic, that the dozens and dozens of qualified engineers at one of the largest car companies in the world designed, tested, redesigned, tested, honed, tested and fitted all that stuff on for no reason whatsoever; and actually it's better to just stick some plastic house guttering and remove them multirams altogether."

Effectively the multirams are there for a reason, and no power is to be gained from their removal or modification (that's if we follow that power is an actual entity - which it isn't, it's only a mathematical number. Torque exists, and torque is what you feel when you accelerate etc, and helping engine torque is what those multirams do).

As you've said, the G cam mod is the best, as is 2.6/3.2 exhaust manifolds (but one side is a pain to do - but possible) leave the existing 2.5 Throttle Body there, generally. As said, if you want out and out 'power', then get a 3.0 in there, but owning one myself, personally find nothing wrong with my 2.5, and will be doing the G cam mod myself this sumemr, plus the extras  Sounds like you're on the right track, OP 

[BigDov]

not after out and out power, got a stage 3 astra VXR for that, but generally just want more grunt from the V6, and being the estate it needs all the help it can get, if we can get it above the 200 mark I'd be happy

will add the exhaust manifolds to the list, guessing they are more free flowing than the 2.5's? also got a 3.0 lower plenum divider on the list.

as for the rechips, seen a guide on here as to how to do them and looks fairly straightforward, but can't seem to find anywhere reliable that sells them, always a bit weary of ebay sellers and ECU chips, how much would I be looking as for a ecu chip for the x25? cruise economy may make it worth while however as the car will be doing a 4500 mile road trip next year.

[Diamond Black Geezer]

Theoretically (assuming your engine is tip-top, and hasn't lost much bhp over the years)

Long plenum,
3-litre inlet divider
G Cams
2.6/3.2 (yes, correct, free-er flowing) manifolds
Honing and polishing the throttle body may get you 0.1bhp, too. At full throttle 
No personal knowledge of chips, the general consensus is tune the engine using good old fashioned big oily bits of metal, so mechanically, not electronically, however, I'm sure that will get you some more of that elusive power.

...the above should get your X25XE to the Vectra GSi-spec, so 195bhp.

If you're after over 200 bhp, though, realistically you're looking at a 3.0litre, which does 210bhp (or thereabouts) that without any engine mods. 

[zirk]

not after out and out power, got a stage 3 astra VXR for that, but generally just want more grunt from the V6, and being the estate it needs all the help it can get, if we can get it above the 200 mark I'd be happy

will add the exhaust manifolds to the list, guessing they are more free flowing than the 2.5's? also got a 3.0 lower plenum divider on the list.

as for the rechips, seen a guide on here as to how to do them and looks fairly straightforward, but can't seem to find anywhere reliable that sells them, always a bit weary of ebay sellers and ECU chips, how much would I be looking as for a ecu chip for the x25? cruise economy may make it worth while however as the car will be doing a 4500 mile road trip next year.

I used to be able to get proper SuperChips for the 3.0 at a reduced rate from my Chip / ECU Man, but there not cheap but a lot cheaper than from SuperChips, but haven't had any for a while now.

The last batch I had and tested seemed to work well, they were Courtenay Sport type remaps which were designed to work in conjunction with widened CS Throttle Bodies although they worked fine on there own and gave an increase in drivability and improved mpg, they were around the £95 mark, so another batch should be similar price.

I'd be a bit careful with eBay ones, heard various stories about them, including throwing the EML fault light on.

Another thing you add to the list if your doing some mods is a Stainless performance exhaust system, that will also improve things, but being an Estate might not come up for a while, also assuming its not too loud and the price is right.

[Phil L]

I see you mention the 2.5 & 3.0 engines a lot... do you have any view on re-chips for the 2.6 ?

[deviator]

...the above should get your X25XE to the Vectra GSi-spec, so 195bhp.

Wasn't that a G & A cam setup? I thought the 4 x G was even closer to 200.

[BigDov]

well we have 2g's and 2a's in our possession or will do this weekend.

The other guy working jointly in this prodject was at billing at the weekend and got talking to a few guys we know and they happen to have a few V6 spares knocking about including another set of G cams, long plenum, 3.0 inlet divider and possibly some 3.0 manifolds, which they are bringing up to the Scottish car show for us this weekend

[zirk]

...the above should get your X25XE to the Vectra GSi-spec, so 195bhp.

Wasn't that a G & A cam setup? I thought the 4 x G was even closer to 200.

4 x G's, not much in it, makes it more aggressive at high RPM's, but you lose some Torque within the normal lower Rev range.   .

Some Veccy boys claim fitting 4 x G's on the Vectra makes the drivability worse, guessing probably down to the lack of multi rams, in my experience having driving an ex plod 3.0 Omega with 4 x G's and a remap, it did fly when you floored it.