Projekte

Alex builds a Quattrini 252cc Vespa engine 3 - expansion stage 2 with exhaust test

Monday 15 November, 2021

Quattrini M244 Kingwelle – the Super-Tourer in the second upgrade "Exhaust" M244_2

M244 – Part 3 In the second part of this series, we simply adjusted the cylinder and engine case together and installed the cylinder onto the engine without further modification as "Plug & Play." This resulted in very moderate timing angles:

with 124° transfer angle
and 177° exhaust angle

Some exhaust systems handle these short timing angles well and already provide quite impressive performance. Exhaust systems tuned more for power, however, require larger timing angles. Throughout the test series, the performance curve character of certain exhaust systems will change. Therefore, we remove some material from the exhaust port and set the exhaust upper edge to 182°. The exhaust width remains unchanged at around 57% of the chord measurement. We use a 1.5 mm spacer at the cylinder head and cylinder base, plus a 0.3 mm gasket at the cylinder base. This keeps the timing angles at 124°:

124° transfer angle
182° exhaust angle
57% chord measurement

Cylinder cooling cover for the long M244 Quattrini

In the meantime, we have also received a matching cylinder cooling cover from fiberglass specialist BSK. You can find the blog about it here -> QUATTRINI GFK CYLINDER COVER

TEST ELRON

The Elron handles the larger timing angle rather conservatively. With a 1.7 hp increase in peak power, a slight loss in torque, and a slightly narrower power band due to the 300 RPM later power onset, the exhaust shows that it acknowledges this requirement, but it is still not the right fit for the concept. However, the Elron takes this very calmly. The exhaust will likely still provide a nice power curve even with significantly different timing angles, so the concept does not fully conform to the timing angle dictation.

Dyno diagram as a PDF: M244_1_2_ELRON

TEST POLINI BOX

The Polini Box reacts very clearly to the small change in the exhaust port and adds significant power. Over 3 hp and almost 1 Nm more. The power band even widens by 700 RPM, with the graph crossing the 25 hp mark at 5,500 RPM, and holding the power much longer up to 9,400 RPM. The timing angles of 124° to 182° seem to suit the Polini Box very well.

Dyno diagram as a PDF: VGL_M244_1_2_POLINI

Test Scooter and Service NEWLINE

The Newline generally shows a different character in the power curve with small timing angles compared to the Elron or Polini Box. Similar to the Elron, the response to the changed exhaust timing angle is rather unremarkable. Peak power increases by almost 1 hp, maximum torque stays almost identical, and the power band is slightly narrower due to the later resonance start, just like the Elron. Even in the second upgrade stage, the Newline maintains the top position for torque with 36.7 Nm at 6,137 RPM.

Dyno diagram as a PDF: M244_1_2_NEWLINE

Test Posch Nessie

The Nessie, which is also intended for moderate timing angles, shows a clear shift in resonance start. In absolute terms, the Nessie adds "only" 2.5 hp at the peak, but between 6,300 RPM and 9,000 RPM, you can clearly see that the larger exhaust angle boosts power significantly over that range.

Dyno diagram as a PDF: M244_1_2_NESSIE

Test Posch Racing Resi

The Racing Resi, with its impressive, stocky appearance, already gives the impression of power and a hunger for timing angles. Therefore, the slightly increased exhaust angle is still not enough for peak power. The resonance start is clearly delayed here as well. At the peak, the Resi gains 1.7 hp, which can be utilized by the slightly higher exhaust timing between 7,300 RPM and 10,000 RPM to boost both power and torque.

Dyno diagram as a PDF: M244_1_2_RAC_RESI

Test Kingwelle Lakers

The robust race exhaust from Lake Constance has already shown that it is a good all-rounder on the M244's installed version. As with all the other tested resonance systems, the power band shifts toward higher RPMs, but without the band width suffering. With a power band of nearly 4,300 RPM, it offers the largest band width in this upgrade stage. With 37.8 hp at the peak, the Lakers just narrowly loses out to the Resi, which has 37.9 hp – but we're just warming up with the timing angle topic.