Cadillac Owners Forum banner

1 - 1 of 1 Posts

Platinum 2001 Cadillac Catera Sport
1,840 Posts
Discussion Starter #1 (Edited)
I wrote this up for Catera owners whose engines have suffered a timing belt failure. No reason it couldn't help CTS owners who've had the same misfortune. I got the details from The Omega Owners Forum over in Great Britain. They tell me it's been done there with good results and that one of the upgrades is done to their police Omegas for improved performance. Mixing parts from the 3.0L Catera or Saturn, th 3.2 CTS, and Saab 2.5L will get you 20 to 30HP over the 220 HP of the stock 3.2L V6, plus approx. 20 lbs/ft more torque, all with stock GM parts. If you have a trashed 3.2L in your CTS and you plan on rebuilding the engine you might consider this. I have a 2001 Catera Sport with a healthy stock 3.0L V6 but if it ever eats its valves I plan on doing this.


While visiting the Omega Owners Forum (OOF) site I stumbled upon an upgrade for the Catera's 54 degree V6 engine. Not exactly easy or cheap, but short of the 3.8 V6 or 5.7 V8 swaps and turbo pipe dreams, the only way to potentially add 40 to 50 horsepower to the Catera. It's accomplished with stock GM parts (Cadillac/Opel/Vauxhall/Saab/Saturn), and centers on using the 2003-2004 CTS 3.2L V6, plus parts from our Catera's 3.0L V6, and the Saab 2.5L V6.

According to Marks DTM Calib of OOF, we use a 3.2L V6 as the core long-block (with the 3.0L's oil pan), swap a pair of 1993-1998 Saab 900 2.5 liter V6 heads onto it (using the 3.2L's head gaskets), and the 3.2L's exhaust manifolds (they're formed steel rather than cast iron, and are internally wider). The "front pipe" from the Catera (the length of exhaust pipe between the manifold and the catalitic converter), must be modified to match the CTS manifold with some grinding of their flanges. The stock 3.2L has a 10.0:1 compression ratio and produces 220 HP. Replacing its heads with those from the 1993-1998 Saab 900 2.5 liter (B258I) V6 2.5L's (smaller combustion chamber) will raise the ratio to approx.10.8:1.
[notes 1,2,3]

To make the most of the increased compression, the new heads must be ported slighty to mimic the contours of the 3.2L/3.0L head's intake passages so to match their airflow specs. Per Zirk of OOF, we must swap the 2.5L's intake and exhaust camshafts with 4 intake ("G") camshafts from the 3.2L and/or 3.0L engines (both motors use the same "G" intake camshafts). Those cams, plus the exhaust valves from either the 3.0L or 3.2L (sodium filled for better heat transfer), are the hot set-up (no pun intended......maybe?). Some models of the British Police's Omegas used this 4x"G" cam mod for an approx. 18HP boost.
[note 4]

Next we use the Catera 3.0L's fuel delivery setup (injectors, fuel rails) and the 3.7 Bar Fuel Pressure Regulator from the CTS. That combination makes for finer fuel atomization and an improved flame-front. The Catera's stock ECU and sensors will work fine with this hodgepodge engine and though it should be safe to use regular grade gas, I suggest mid to high grade gas. It will protect the pistons by preventing pre-detonation, and exploit the increased potential of the engine.
[note 5]

At this point you could convert to an external oil cooler to avoid problems with the internal cooler leaking, pop in a new thermostat w/gasket, replace the camcover gaskets, switch to Saab aluminum camcovers, convert to a spin-on oil filter, move the HBV to an more accessible location, and replace the Timing & Serpentine Belts as well as their Tensioners. Finally, reinstall the ancillary equipment (Alternator, AC, PS, intake stacks & plenum, etc,).

If you want to take this a step or two further there is a large twin-bore throttle body available from The UK, or go crazy and chuck the entire GM intake assembly altogether, and install 6 individual throttle bodies with air-horns and individual foam filters. If you still have money left over there are aftermarket performance camshafts, a lightened balance pulley (quicker revs), an uprated 4 bar Fuel Pressure Regulator, even a cooler rated thermostat to help with the additional heat generated. There maybe more if you check some German sites and understand the lingo. In the meantime, follow the links below.

Summary: After all this we end up with a 200cc displacement increase, a stronger crankshaft, a higher compression ratio, the best camshafts, the most efficient exhaust valves, the best fuel delivery set-up, freer flowing "factory headers", and an increase in horsepower anywhere from 20 to 30HP over the 220 HP of the stock 3.2L V6 plus approx. 20 lbs/ft more torque, all with stock GM parts. Sounds easier than swapping in an SC3800 V6 or an LS1 V8, doesn't it? True, not as powerful than either of those two but with them you'd have to do lots of custom fabrication, modification, and maybe install a stronger transmission and differential.


Placing the 3.0L heads on the 3.2L block will raise the compression, but not to the 10.8:1 ratio. I would guess to approx. 10.4:1.

Placing the 3.2L heads on the 3.0L block will lower the compression below 10.0:1. I would guess to approx. 9.5:1.

Placing the 2.5L cylinderheads on the 3.0L will raise the ratio above its stock 10.8:1 and could lead to predetonation (pinging) and damage (holing) the pistons, even if using high octane gasoline.

All 3.0L Catera V6s have "G" intake cams and "A" exhaust cams. All 3.2L CTS V6s have "G" intake cams and "J" exhaust cams. Using "G" intake cams as exhaust cams instead of "A"s or "J"s will increase torque and push more of it up into the mid-range, but you don't gain as much off idle. Good for passing manuvers but not so much for stop-light drag-racing.

The 2.5/3.0 had a 3bar and the 3.2 had a 3.7 bar Fuel Pressure Regulator. Upping the fuel pressure will not give extra HP, but it might give slightly better fuel atomization for a better burn, and if you were struggling to fuel it when floored it could help there.

I cannot guarantee this engine will pass emissions testing. If that is a requirement in your state it may fail.

REMEMBER: These mods are based on OOF experience with the European versions of the GM 54 degree V6 engines. As far as they know they should be identical to the engines available here. I'm confident these mods will work, but as always, try these mods at your own risk.

The stock L81/X30XE 3.0L V6:
Cylinder bore 86mm
Piston stroke 85mm
Organic fiber head gaskets
Cast iron exhaust manifold

The stock LA3/Y32SE 3.2L V6:
Larger Bore - 87.5mm
Longer stroke - 88mm
Steel mutlilayer head gaskets
Forged steel crank (stronger)
Larger diameter exhaust manifolds (formed steel)
1 - 1 of 1 Posts