An eighth-inch mismatch in the intake runners seems like exactly the sort of small obstruction worth eliminating, but the dyno quickly establishes the limits of that intuition. After carefully port-matching the transition and repeating pulls to account for normal variation, the setup gains only around three horsepower at peak while trading tiny amounts elsewhere in the curve. Rather than exaggerating such a marginal improvement, the testing sensibly concludes that the modification is effectively negligible, setting an appropriately evidence-driven tone for the larger experiments that follow.
The carbon air box produces another useful non-result. With the filter installed, peak power remains roughly unchanged while the engine repeatedly loses a small amount through the mid-range; removing the filter does little to alter that outcome. There is a reasonable practical argument that the box could still prove valuable once isolated from exhaust heat and supplied with fresh air while the car is moving, but that benefit is not demonstrated under the dyno conditions here. Acknowledging the limitation rather than treating the attractive hardware as automatically superior is one of the presentation's strengths.
Far more revealing is the switch from roughly 21.5-inch total runners to a 15-inch configuration. Drawing cautiously from 787B-related information that the host explicitly says is not perfectly applicable to this engine, he predicts that shortening the runners by about 6.5 inches could move peak torque roughly 2,000 rpm higher. The resulting pull does almost exactly that, shifting peak torque from around 7,500 to 9,500 rpm. It is an unusually satisfying experiment because the expected relationship and the measured outcome are both clearly described without pretending that one successful test validates every underlying assumption.
That result also illustrates why a larger peak number is not necessarily the objective. The short runners substantially weaken the useful middle of the powerband, and the discussion explains why average power matters more than an impressive maximum in drifting, where the engine needs to respond across a usable operating range. The possibility of variable-length trumpets naturally emerges as a way of combining both characteristics, although packaging beneath the hood makes that much harder than simply invoking the famous 787B solution. This combination of theory, physical constraints and immediately visible dyno consequences gives the technical material practical relevance.
The session becomes less controlled once M5 fuel enters the picture, but it is also where the most dramatic numbers appear. Freddie predicts that the short-runner configuration should respond strongly at high rpm, and after adjustments the engine reaches roughly 600 wheel horsepower and 330 lb-ft while recovering much of the mid-range deficit created by the intake change. The participants are appropriately open about their limited M5 experience, with tuning guidance attributed to Jamie Marsh rather than presented as their own established expertise. They also note potential hazards such as methanol's difficult-to-see flame, though the conversation about mixture, timing and why the fuel changes output remains exploratory rather than a rigorous technical explanation.
Presentation-wise, the loose workshop atmosphere is both an asset and a weakness. Watching parts being fabricated, fitted, smoke-tested and immediately evaluated keeps the process authentic, while repeated pulls and ECU data provide more substance than a simple before-and-after horsepower reveal. At the same time, event promotion, side conversations, an unresolved high-idle issue and a possible exhaust leak introduce variables and diversions that prevent every comparison from being perfectly controlled. Even so, the central finding is unusually clear: the small intake refinements barely matter, whereas runner length fundamentally reshapes where the four-rotor produces torque and power.
Pros
- Repeated dyno testing allows negligible port-matching and air-box changes to be distinguished from genuinely significant effects.
- The short-runner test produces a striking, clearly explained 2,000-rpm shift in peak torque that closely matches the stated prediction.
- Discussion of average power versus peak power connects the dyno graph directly to the car's intended drifting use.
- The presenters openly acknowledge uncertainties around the 787B comparison, M5 tuning and possible mechanical variables rather than overstating certainty.
Cons
- The M5 experiment changes fuel as well as intake configuration, making its dramatic power gains unsuitable as a clean comparison with the earlier ethanol tests.
- A high-idle condition and possible exhaust leak introduce unresolved variables into an otherwise methodical testing session.
- Technical explanations of resonance, methanol behavior and fuel effects are sometimes tentative and conversational rather than fully developed.
- Promotional segments and workshop tangents occasionally interrupt the otherwise strong experimental progression.
Careful back-to-back testing turns what could have been a collection of minor modifications into a convincing demonstration of how dramatically runner length can reposition a four-rotor's powerband. Some uncontrolled variables and the improvised M5 experiment limit the scientific neatness of the session, but the willingness to accept insignificant results and explain meaningful ones makes the process both informative and entertaining.
