Same engine with different HP. How/Why?

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Nov 11, 1998 | 07:14 AM

Andrew C

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Same engine with different HP. How/Why?

I know that a number of cars from Audi share the 2.8L 30v engine. Each has a different HP, but the same torque. Is this just differences in the ECU? Emmisions systems?For example US Spec A4 2.8 hp=190 torque=207 EuroSpec A4 2.8 hp=193 torque=207 US Spec A6 2.8 hp=200 torque=207 EuroSpec A6 ???If aftermarket companies say that they have an ECU replacement that will boost HP by "10%" is that relative to each cars' starting hp OR does the 2.8 engine have a maximum hp without degrading fuel, emmission, etc? (i.e. if a company sells a chip for A4 & A6, then they both should have the same final hp?) If this was the case, then the A6 would have the smallest increase due to chipping and the US Spec A4 the largest.I'm not thinking of chipping at the moment. Just curious. I thought that if the change was due to different ECU programming, that the increase in hp would have brought about a similar change in torque too, so the 207 across the board is what I find odd.Don't have any engine performance knowledge to back this up, so please educate me.Andrew 98 A4 2.8qms

Nov 11, 1998 | 07:26 AM

leszek

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A6 has more room in the engine bay, so it has a larger intake manifold.

Nov 11, 1998 | 08:09 AM

Ali B

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I don't believe the 200 hp on the A6!

I honestly think that they wanted to be higher than the BMW 528i. Even in FrontTrak onfiguration, the A6 is pathetically slow (0-60 in 8.8 seconds). It has been the slowest car by a big margin in every multi-car comparison test I have seen so far. The Quattro is even slower (0-60 in 9.5-9.7 seconds). I guess you can blame the Tiptronic transmission for some of this sub-par performance, but automatic models like the Saab 9-5 SE and BMW 528i accelerate from 0-60 in about 7.5 seconds with similar horsepower ratings and the vehicle weights are comparable to the FWD A6. Despite A6's lethargic drivetrain, the car manages to win or tie every comparison test I have seen. This is a testament to it being a very good car in need of a decent engine. Hopefully the promised manual transmission and more powerful engines (230-hp 2.7 biturbo and the V8) will finally put this car on the same playing field with serious luxury sport sedans.

Nov 11, 1998 | 08:27 AM

stevebrown

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I believe it's right...

Same engine with different intake/exhaust can make different power...There is definitely more room in the A6 engine bay & the exhaust could be routed more efficiently (don't know myself cuz I haven't looked at one).The A6 I sat in had more interior room "feel" (don't know numbers), than the 528 I tested. It might also be heavier, geared differently, etc.I really think you attribute far too much to 0-60 numbers. They can be affected by so many factors that trying to make some kind of direct relationship with HP and 0-60 times is quite ridiculous...Hell, the Dodge Viper is TRACTION LIMITED in its 0-60 numbers, so when Hennessey modifies it & gives it like 700 hp, the 0-60 times don't move as much as you would think from the hp gain...can't put it to the ground...this is just one example... steve

Nov 11, 1998 | 08:31 AM

MartinR

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Re: Same engine with different HP. How/Why?

As I understand it, the A6 has larger engine bay, which results in better intake manifold and better exhaust manifold resulting in slightly more power.

Nov 11, 1998 | 08:59 AM

JohnS

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The A6 2.8 has a plastic intake manifold and dual exhausts....

The plastic intake manifold supposedly gives the engine slightly more power because it keeps the intake air cooler, and dual exhausts allow it to breathe better. JohnS