c25xe - x30xe

archiewood

Newbie
Points
21
Location
Coalville, Leics
Car
Cavalier V6
Hi all. I'm looking at upgrading my V6 Cavalier to a 3.0L. I want to keep the dual rams - can anyone tell me what's involved in lowering the engine sufficiently to fit them in?

Do the engine mounts height-adjust at all, or do I need to get new ones made?

How much lowering is needed to fit the intake into the Cavalier bay?

Does the engine have to be lowered far enough that it's going to affect the exhaust?
 
Hell mate and welcome to the site. Where abouts are you from.

Right, for starters, i'm going to assume you are refering to the duel throttle body that is on some 3.0 Vauxhall engines. This you will need to swap for the exact inlet set-up from your 2.5. No need for the 3.0 ECU aswell as the 2.5 ECU is absolutly fine on the new engine ;)

You Can make it even easier for yourself if you use everything of the 2.5 apart from the main bottom end. Use the 2.5 heads, 3.0 cams, and the 2.5 Calibra/Cavalier Inlet manifold. You need this inlet due to the larger top end on the Vectras and Omegas not fitting under the hood of a Calibra or Cavavlier.

I have done this conversion myself in the past with my old V6 Calibra (green one in my sig) and am driving a Courtenay Tuned and Converted 3.0 Calibra (red one in my sig) so i'm more than happy to help out ;)
 
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Thanks a lot! I'm near Loughborough.

I want to leave the engine standard (I know the sump has to be from the 25, but apart from that), or for me it's not worth the effort. I've read that others have fitted it without changing the induction, and I've seen a Calibra with a standard-inlet x30xe in it.

A bit lacking in details how to do it though. Sounds like the right/left mountings just need a spacer, but the rear is on the subframe so might be problematic. I'm scheming to buy a mount and replace the poly lining so I can reposition the mount point. Whether that would work really depends on how much of a drop is needed for it to fit.
 
Nope, aslong as your car is a 2.5 already, you dont need to change a thing to get it to mount properly. You only need the spacer if you are fitting the F28 6 speed gearbox as you need to move the engine over by 23mm.

But aslong as you already have a 2.5 V6 then all you need to do is take the cams and both heads off replace the 2.5 bottom end with the 3.0 bottom (exactly the same size externally so will fit no problem) fit the 2.5 heads to the 2.0, then put the 3.0 cams in and fit the 6 branch inlet manifold from your cav or a calibra (only 2 with this shape inlet). The air box throttle body and ecu can remain the same. All this will knock you up to the standard 3.0 mark of 210bhp then it's up to you how much further you want to take it.

If you want to use the inlet from a Vectra/Omega then you will be waisting your time as these inlets actually restrict the air flow hence using the simpler Cav/Calibra inlet. Also, alot more expensive to get gas flowed in the future than what the Cav/Calibra inlet is as there is one more section on the inlet. So dont use the standard 3.0 inlet, use the oroginal from your 2.5 as this flows alot better ;)
 
I have tried all three types of inlet system,Cav/Calibra;Vectra;Omega on my 3 litre and have concluded;

Std cav type is too small for the 3 litre engine, the ports restrict the airflow at higher rpms.When I fitted the vec type I picked up 43hp at 6500rpm.Low down driveability was very good though.

Vec type picked up the top end due to larger diameter ports and better shape compared to the cav dog leg type.Driveability was worse,the shape of the whole system is poor IMHO,where the TB leads into the centre plenum the airflow runs straight into an angled face.I also think the whole system is too large for the engine capacity and ruins the transient throttle response.I did measure it and found it is more than twice the volume of the engine and I read somewhere that the ideal size is around 60-80% of your engine CCs.I think Vectra flat spots are well known.
Fits under the bonnet ok though.

Omega (short type) .Just about fits under the bonnet,I had to "reshape" a bonnet support rib to clear the TB and also move the idle valve to the rear of the plenum as it hits the bonnet at the front. IMHO this type has the best shape intake port,nice and straight(maybe a bit too short though) with a bellmouth in the upper plenum and also benefits from larger TB area.Compared to the vec type,it feels like it has lost some mid range torque which is probably due to the shorter intake runners,but feels much stronger at higher rpms.This agrees with my power curve I had with the vectra type compared to Canems Capri power curve with Omega type.Different car and rollers I know, but the trend is clear.

Other pluses are it is lighter than the vec set up(good for my RWYB plans) and with less metal around, less prone to heat soak.

I have got a programmable ecu(Canems) to go on the car and the company I bought it from had fitted a 3litre VX into a Capri with the Omega manifold on and got 238bhp from it, so thats where I'm aiming.

Except for the std type, I can't run a std airbox as there isn't enough room for it when the TB comes out the middle of the Vee, so mine is down behind the front bumper with the O/S foglight taken out for a cold air feed.

Bad63r,I see you are in Warwickshire,anywhere near Rugby?
 
Just posting for posterity as I no longer own the car, sadly.

The 3.0 did go in successfully with no modifications to the mounts needed - reading iancav6's post above, it looks like the fact I also fitted an F28 helped me as I didn't need to do anything to the bonnet support.

However, I was absolutely determined to preserve the multiram system from the omega, so I came up with this:

EgKMv.jpg


A lot of messing with silicone tubing and aluminium pipes! I made a 'T' section to split the intake tract out of two chopped-up air mass meter housings. Obviously no room for an air box so I put a cone filter behind the bumper as iancav6 did. It was all a very tight squeeze.

The hardest part to find was the flexible ducting between the TB and the two intake tracts. They turned out to be essential as I lost my engine stabiliser bar and couldn't find a replacement, so there was quite a bit of engine rotation under acceleration. You can see the rusty part on the top of the hose clamp for the right ducting, where it rubbed on the bonnet support.

The air con had already been ripped out of my Cav but the vacuum reservoir was still there, so I used that to plumb in the multi-ram valves, though I never got around to making a controller to operate the solenoids. You can see a red zip tie near the bottom of the picture, from when I was experimenting with the different valve configurations. Opening the lower valve improved the pull at high speed and didn't seem to hurt the low end.

Just posting in case anyone else is considering this project - well worth putting in the time to build an intake that preserves the Omega intake system. I realise what I made was a kludge, but it seemed to work well.

Your post was held in the moderation queue because you posted an image before you had made 10 posts as per our T&C's. I have approved it for you this time.
T9 man
 

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