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Originally Posted by Nubodi Automotive
Sarcasm is definitely the lowest form of wit. As I stated my car went from 231 BHP to 259 BHP. When I went to school that made 28 BHP. Most remappers will GUARANTEE (or your money back) 10-15%. Perhaps you went to a different school?
28BHP is in the middle of this range. And not a throttle body or cam in the equation. I was fairly happy with this although not ecstatic.
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In an earlier post, Richard claims that a gain of 30-40bhp in peak power is possible by remapping an otherwise standard, naturally aspirated BMW Z3. From personal experience he claims his 3 litre Z3 gained 28bhp rising from 231 to 259bhp. I don’t know why his car falls outside the full increase he reckons is available.
In my humble experience, this is not achievable and I stated this here at the time. For N/A motors I place it in the same camp as raiki, acupuncture, fortune telling and so on. It seems that many people put their belief in the fact that because a remap can achieve significant gains on supercharged motors (whether supercharged or turbine supercharged (ie turbo)) then a similar gain, naively, must be possible on naturally aspirated motors.
A number of reputable remap tuners state that a potential gain of 10-15bhp is possible on this motor. The very experienced Superchips claim a 14bhp gain, and it is worth noting that this is in the less useful rev range beyond maximum power - not an increase in maximum power as Richard’s tuner claims can be achieved. Up until maximum power, the Superchips increase is between 5 and 10bhp (my interpolation from a Superchips power plot).
I’ll use the term power throughout, as that’s what we’re discussing. In reality, we’re increasing engine torque – which is measurable, whereas power is a simple calculation.
So, let’s think of this logically. Returning to first principles, an internal combustion engine is a pump. Air is sucked in, mixed with the correct volume of fuel and exploded at the right moment, and gas is exhausted. Extra power can be gained by increasing the gas flow through the engine, increasing the amount of fuel being burned, or exploding it more effectively, or at a more optimum time. To burn more fuel, the volume of air will also need to be increased and this returns us to the fact that to increase power substantially we will need to increase gas flow. If we increased the volume of fuel and air into the engine then we should produce more power. It’s easy to increase the amount of fuel – a remap can do that, but to explode it to achieve maximise power we need a volume of air about 14 times larger – and that’s hard to suck into the engine without removing physical obstructions to air flow. A gain of 40bhp is an increase of around 17% - to achieve a similar increase we would need an engine size increase to around 3500cc. That’s a high expectation for a remap and realistically unobtainable. Next, we’ll discuss why.