Yeah sorry john, its a cracking Megga 
I have spoken to quite a few people who got a Senator past 165, but they did have manuals, de-cat & chipped.
The official figures from Vauxhall are a lot like the BMW, very understated. on the Autobahn stomers for sale section, there was a mint Senator which had been on a rolling road.
It was factory standard: - "car is completely standard and un-modified, it produced 234.5 BHP, and 193 lb/ft Torque"
Link is here: http://www.autobahnstormers.co.uk/adverts/senator_b_for_sale.asp
Its the top Senator...
So its already at 234bhp without any mods!
Chassis rolling roads are a pretty questionable way to get engine BHP, the figure they measure will be far short of that due to transmission loss (through the gearbox, diff, contact patch on the road wheels), then they extrapolate back to estimate the flywheel BHP. Not particularly accurate, and even worse on an automatic when you can't keep it in one gear for the entire run, plus the torque converter further screws up the measurements. I remember on the Subaru forums where loads of members had their car rolling roaded on a regular basis, it was common to have a difference of 20 BHP or more on exactly the same car but two different dynos - and that was with manual gearboxes. So take the figures with a pinch of salt - for making comparisons before and after mods on the same car they're great, but if comparing against other cars it needs to be done on the same dyno with the same conditions. You may well find that a standard Omega MV6 manual will also produce 230+ BHP on that dyno, but it doesn't necessarily mean the engine is producing 20 BHP over stock figures. What also concerns me is that the torque figure is pretty low for an engine producing 234 BHP, it'd be interesting to see the printout cos that means the engine is producing no more torque than stock, but is doint it higher up the rev range than stock.
And even at 234 BHP, you're still far short of the required power. A decat and chip isn't going to get you 70 BHP on a normally aspirated engine. Getting 300 BHP from a 3 litre is no mean feat - that's 100 BHP/litre, which is a very high specific output for a NA engine, and requires that the engine is carefully designed to ensure maximum flow at high revs (manifold design, heads, high lift cams etc). The Honda Civic Type-R engine only just manages 100 BHP/litre, and it does so by revving to 8,000 RPM along with the VTEC system giving variable valve duration and lift. The intakes and exhaust manifold will have been designed by the manufacturer to allow maximum flow at high revs - this is one area that would strangle the Omega engine, and most likely the Senator too, as the exhaust manifold simply wasn't designed to be high flowing for peaky power.
Don't get me wrong, the 840Ci is no flying machine; there are plenty of cars that will obliterate it off the line (although none of them are Omegas, unless you count the Lotus engined one
). But where it does well is top speed, as it has the two things that you need: power and aerodynamics. There's no changing the fact that unless you have a really aerodynamic car, you need lots of power to obtain high speeds, and it's diminishing returns - as speeds increase, you need more power for less gain. Hence why the 850CSi, which has the same low aerodynamic drag as the 840Ci but 380 BHP, will do around 184 MPH. That's an increase of 65 BHP to get only 11 MPH. To get the next 16 MPH for the 200MPH that the new M5 does required another 127 BHP (although it does have slightly poorer aerodynamics).
One final point... the guys getting Senators past 165 MPH, did they measure that using GPS or radar? Cos if it's the speedo, it's guaranteed to be well out at those speeds, especially on such an old car. I'm sure my manual MV6 could hit the limit on the speedo (160 MPH), but I have serious doubts as to its potential to reach those speeds. The numbers just don't add up, and you can't override the laws of physics.
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Topic: Senator/Beemer 840 (Read 3925 times)