VVC Cone filter results

Figure 1. All the cone filter data illustrated.

A difficult figure to read this one, but I would draw your attention to the lines with the open circles (blue and red). These are the standard power curves. As can be seen, the all the cone filters make a clear gain over standard in both power and torque.

The four filters put themselves into two groups: those with a spacer tube between the filter and the throttle body, and those that are clamped directly to the throttle body. Within these two groups, the filters are indiscerbable from their power curves.

The filters with spacer tubes have a clear advantage over those that don't. (K&N and Ramair versus the two Pipercross products).

Figure 2. Pipercross Vector versuses standard. Filter representative of a filter clamped directly to the throttle body.

The Pipercross filters result in an impressive performance gain over the standard paper element, with a gain of around 8 bhp. Given that this filter type can be purchased for less than 30 UKP, this represents excellent value for money (approximately 0.3 bhp per pound sterling).

Being mounted directly to the throttle body results in more noise than the Ramair or K&N 57i- which is either a good thing or a bad thing depending upon how you view these things.

The Pipercross filters do not win overall in the performance stakes however.

Figure 3. K&N 57i filter versus standard filter. Filter representative of a filter clamped to the throttle body via a spacer tube.

The performance of both the Ramair and the K&N products were close to inseparable, the K&N giving a marginal 1 bhp advantage over its close competitor. The difference between these filters and the Pipercross cones is the defference between a 15 bhp gain versus an 8 bhp gain in power over standard. The torque curves also show a concomitant improvement.

The Ramair and K&N products are separated on price however- the K&N can be purchased for less than 100 UKP, compared with the Ramair @ 140 UKP.

The performance per pound quotant for the K&N therefore works out at 0.15 bhp per pound sterling.

The K&N and Ramair products clear gave the best performances. Factor in costs, and the K&N clearly wins the contest between these two filters. However, at 0.15 bhp per pound versus the impressive 0.3 bhp per pound of the Pipercross product, is the K&N worth it? Ultimately that is a decision that lies in the hands of the prospective purchaser. Given the clear power advantage of the K&N the investigators were happy to give this product the thumbs up.

One further consideration is that of induction temperature. The higher the temperature of the air entering the engine, the less dense, and therefore, the less oxygen that the air contains for combustion. A lower temperature is desirable for more power. These rolling road tests were performed with the intake temperatures equalised for each filter tested. Both the K&N and the Ramair filters come with cooling ram ducts to cool the filters' intake charge; the Pipercross filters do not come with this refinement. Investigations with temperature probes have revealed that under normal driving conditions the Pipercross filters would suck in air up to 10 celcius or more than the K&N or Ramair filters. This would effectively abrogate any advantage the Pipercross filters might convey. Therefore it is advantage K&N.