I dont understand the issue? Why couldn't the VS ute make the same power as a VT? Twin exhaust does not mean it will make more power?

Yes but as far as I can make out, the issue is that the earlier car should be rated at less power.
The statement is that for the ute to make the same power as the VY it would need a twin system. Twin systems don't always make more power, in fact I was under the impression that a 5 litre made more power with a good single system.
But that is irrelevant as Holden has listed them as the same power DIN which is measured with an exhaust system in place is it not? It may not be the same exhaust system as is on the car though is it? If that was the case they would have different power ratings for all models in a series even if they all had the exact same spec engine.
However, cars are not perfect, you could buy 10 identical cars and they would all feel different to drive.
As for the VY vs VZ, do they have the same diff ratio, gear box ratios, wheel size, driven by both drivers to do an accurate test? How many K's on each car and what condition is the engine in? To test two stock cars they need to be brand new for it to be accurate. And then you would need to test several and average the results.
Seat of the pants is a guess at best.

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Originally posted by wbute
Yes but as far as I can make out, the issue is that the earlier car should be rated at less power.
The statement is that for the ute to make the same power as the VY it would need a twin system. Twin systems don't always make more power, in fact I was under the impression that a 5 litre made more power with a good single system.
But that is irrelevant as Holden has listed them as the same power DIN which is measured with an exhaust system in place is it not? It may not be the same exhaust system as is on the car though is it? If that was the case they would have different power ratings for all models in a series even if they all had the exact same spec engine.
However, cars are not perfect, you could buy 10 identical cars and they would all feel different to drive.
As for the VY vs VZ, do they have the same diff ratio, gear box ratios, wheel size, driven by both drivers to do an accurate test? How many K's on each car and what condition is the engine in? To test two stock cars they need to be brand new for it to be accurate. And then you would need to test several and average the results.
Seat of the pants is a guess at best.

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They do have different power ratings for different exhaust on holden 5.7L gen3.
And yes they use the original exhaust to test them all.
Looky hear VZ Commodores V6 3.6L 190 KW @6500 -335 NM@ 3200RPM. and The AVENTRUA wagon has 188KW @ 6500 -330 NM @ 3600RPM ? exhaust.

Sure there will always be some difference in performance of the same type of car.
Testing at the rear wheels would not be as accurate as at the fly wheel.

As to the 253 vs 307 thing the 307 were so restricted in the HK-T just like the 308 with the single little exhaust that a twin or a good single 2 1/4 exhaust 253 would be all over them and the poor old 307 had only the 2BBL carby.
308's have to have good flowing exhaust or they are gutless and all single sound like crap, in all V8 and i have tried both and a good twin is always better performing and you don't get that sicking drone.

They have twin systems big enough to stick a 308 inside by the way.

Not to mention the engines are in different series cars. Is the weight the same between both cars?
Peak power ratings only tell you the peak power at a certain rev point. You need to consider the torque figures as well.
I know diesels are boring, but it shows how several engines all rated the same can perform totally differently. The quoted power figures are inaccurate in the real world.

just by looking at the cam tunnel will not tell you if it had core shift in the bores, there are other tools to gauge bore thickness, i once read that chev v8,s were all within 5h.p of each other when dyno tested and timing set, that is i.e same spec engine how is that for mass produced and all eight pistions were fitted in under thirty seconds, the chev v8 had the leat amount of sand cores to produce a block less chance of core shift and chev just made there 100 millionth v8 in december.
pete