Omega Owners Forum
Chat Area => General Car Chat => Topic started by: minifreek on 13 April 2015, 22:24:50
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Will a 3.2 crank fit a 3.0 and work 100% please :)
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I'm afraid not. The stroke is different.
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Would, just out of interest, a combination of v engine parts give better compression on the 3.2?
I remember master saying the 3.2 and 2.6 had lower compression for some reason.
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Last I heard this required someone to try it - yes there is a different compression ratio but whether this would give any gain or simply spoil things elsewhere, not sure. Remember there's a computer there always trying to 'correct' things - a bit like the higher fuel pressure 'mod' - the engine will simply say 'oh, too much fuel - back off a bit' 3.2s/2.6s have the lowest compression iirc
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Yes, you'd really need a big box of bits and play around until something fits.
You need to reduce the size of the combustion chambers to increase compression. Best potential is to fit a 2.5/2.6 head to a 3.2, IMHO. Might need to open the ports out a bit to bring the flow up to that of the original head, and fit the sodium filled exhaust valves of the larger engine. IIRC, the valves are the same size.
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Last I heard this required someone to try it - yes there is a different compression ratio but whether this would give any gain or simply spoil things elsewhere, not sure. Remember there's a computer there always trying to 'correct' things - a bit like the higher fuel pressure 'mod' - the engine will simply say 'oh, too much fuel - back off a bit' 3.2s/2.6s have the lowest compression iirc
Ecu doesn't control compression though. Obviously....
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No, no, indeed. My point being simply that if you alter something on a modern engine in order to 'make it go faster' there's often an ECU somewhere in the mix to compensate, so this need bearing in mind, is all.. :)
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No, no, indeed. My point being simply that if you alter something on a modern engine in order to 'make it go faster' there's often an ECU somewhere in the mix to compensate, so this need bearing in mind, is all.. :)
Indeed. An argument often reserved for the ins and outs of chavs fitting uprated fuel pressure regulators without touching any other part of the engine, as the Ecu will simply trim back injector duration to match the same lambda signal. As it would of course.
Compression however, if increased at least to match the 3.0 would in theory give a bigger bang for the same fuel air mixture. ...obviously needs to remain within limits but there's no obvious reason why the 3.2 needs less compression for .2 bigger cylinder capacity afaik.
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Indeed. An argument often reserved for the ins and outs of chavs fitting uprated fuel pressure regulators without touching any other part of the engine, as the Ecu will simply trim back injector duration to match the same lambda signal. As it would of course.
Compression however, if increased at least to match the 3.0 would in theory give a bigger bang for the same fuel air mixture. ...obviously needs to remain within limits but there's no obvious reason why the 3.2 needs less compression for .2 bigger cylinder capacity afaik.
Yep, absolutely right. More compression will give you a little more power from the same charge of fuel in the cylinder, so the ECU will know no different. The only potential fly in the ointment is that the ignition map might not be ideal but, as long as it doesn't give so much advance that you get knocking with the higher compression (unlikely with only a modest increase), it probably won't lose you much.
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.. and, of course, if LPG is your fuel, more compression can be accommodated easily due to its' high effective octane rating.
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Ignition no issue as the knock control will compensate.
ECU wont notice, the compression ratio was only lowered to reduce cylinder temperatures and hence NOx generation allowing removal of the EGR valve.
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Ignition no issue as the knock control will compensate.
ECU wont notice, the compression ratio was only lowered to reduce cylinder temperatures and hence NOx generation allowing removal of the EGR valve.
Oh is see. But how very disappointing. ;D
Makes it somewhat tricky to remove factory "fitted" gubbins that purely exist to meet EU/emissions regs. On a bike it's just re mapped with a filter(but not these days) and free flowing exhaust and bingo, an as Mr Honda/Yamaha/Kawasaki/Suzuki intended engine is ready to go. No flat spots or overly safe fuel fuel mixture. Just crisp throttle response and a few more bhp.
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I always think back to Obi - 3.0 block with 3.0 heads (later ones with the reservations to allow the use of per bank dispacks) and 2.6/3.2 ECU (So Motronic 3.1.1), manual box and 2.6 standard diff. Or at least I think that was the spec.
That seemed a fab combination, 3rd gear just kept pulling from 20 Mph up to illegal digits with a constant flow of torque.
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Ignition no issue as the knock control will compensate.
ECU wont notice, the compression ratio was only lowered to reduce cylinder temperatures and hence NOx generation allowing removal of the EGR valve.
Oh is see. But how very disappointing. ;D
Makes it somewhat tricky to remove factory "fitted" gubbins that purely exist to meet EU/emissions regs. On a bike it's just re mapped with a filter(but not these days) and free flowing exhaust and bingo, an as Mr Honda/Yamaha/Kawasaki/Suzuki intended engine is ready to go. No flat spots or overly safe fuel fuel mixture. Just crisp throttle response and a few more bhp.
....and this is all because of cold starting?
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Errrrrrrrrm......
Thanks for the answer :)
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Have you given thought to the 4xG Cam mod?
http://www.omegaowners.com/forum/index.php?topic=126532.0
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Ignition no issue as the knock control will compensate.
ECU wont notice, the compression ratio was only lowered to reduce cylinder temperatures and hence NOx generation allowing removal of the EGR valve.
Oh is see. But how very disappointing. ;D
Makes it somewhat tricky to remove factory "fitted" gubbins that purely exist to meet EU/emissions regs. On a bike it's just re mapped with a filter(but not these days) and free flowing exhaust and bingo, an as Mr Honda/Yamaha/Kawasaki/Suzuki intended engine is ready to go. No flat spots or overly safe fuel fuel mixture. Just crisp throttle response and a few more bhp.
....and this is all because of cold starting?
No.. Nothing to do with cold start. Probably more because it was cheaper for GM to reduce the compression and increase the displacement a little than to fit EGR to the engine. ;)
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Have you given thought to the 4xG Cam mod?
http://www.omegaowners.com/forum/index.php?topic=126532.0
2 off G cams on the inlet is a good approach, might as well use the A's for the exhaust as there is little to be gained with the exhaust cams being upgraded. :y
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I fitted the 4 x G cams to my 2.5, along with the 3.0 divider and fitted the long nose plenum from the 3.0 also.
With just the g cams fitted, there was a noticeable loss in low end torque, but once the cams switch on they do make good power.
I fitted the long nose plenum to get some of the low end torque back, and it has worked. there is noticeable gains to be had from fitting the 4 x g cams, but they also need to be fitted with the other 'mods' also to get noticeable gains from actually fitting them...
My omega was RR'd at A&M Conversions in Sealand, Deeside... who are Vauxhall tuning specialists. The operator couldn't get the true power from the engine but in his experience was confident that my engine and combinations of other things fitted, is producing 235BHP, which Im quite happy with. He did say that the gasflowed Vectra Challenge heads have helped also... :)
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Have you given thought to the 4xG Cam mod?
http://www.omegaowners.com/forum/index.php?topic=126532.0
2 off G cams on the inlet is a good approach, might as well use the A's for the exhaust as there is little to be gained with the exhaust cams being upgraded. :y
What do you mean by 2 off G cams? I thought using the G cams as both intake and exhaust was the hot ticket.
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4 G cams will give BHP. The A cams seem to offer more torque and the J cams make great door wedges.