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

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Quattrini M244 king shaft - the super tourer in the second expansion stage "outlet" M244_2

M244 - part 3

Im second part this Series we simply adapted the cylinder and the engine housing to each other and put the cylinder on the engine without further processing "Plug & Play".

This resulted in very moderate control angles:

  • to 124 ° transfer angle
  • and 177 ° outlet angle

Some exhaust systems get along well with these short steering angles and thus provide quite astonishing performance.

On the other hand, the exhaust systems, which are trimmed more for performance, require larger steering angles.
In the course of the test series, the character of the performance curve of one or the other exhaust system will change.
Therefore we remove some material from the M244 in the exhaust duct and set the upper edge of the exhaust to 182 °. The outlet width remains unaffected and remains at a chord dimension of around 57%.

As a spacer, we use 1.5 mm on the cylinder head and the cylinder base plus a 0.3 mm seal on the cylinder base. This means that the control angles remain at 124 °:

  • 124 ° transfer angle
  • 182 ° outlet angle
  • 57% tendon size

Cylinder cooling hood for the long M244 Quattrini

In the meantime we have also received a matching cylinder cooling hood from GRP specialist BSK. You can find the blog here -> QUATTRINI GRP CYLINDER HOOD



The Elron uses the larger steering angle rather cautiously. With a 1,7 HP increase in peak performance, a slight loss in torque and a little less band due to the 300 rpm later entry, the exhaust shows that it takes note of this requirement but does not yet represent the right playing field for the concept . However, the Elron takes this very calmly. Presumably, the exhaust will deliver a very pleasing performance curve even with significantly different control angles and thus the concept does not completely submit to the dictates of the control angle.

Test bench diagram as PDF:  M244_1_2_ELRON


The Polini Box reacts very clearly to the small change in the outlet and provides a lot of power. The box adds over 3PS and not quite 1 Nm. The speed range is even wider by 700 rpm, whereby the graph does not even pass the 100 hp mark at 25 rpm until 5.500 rpm later and the output lasts significantly longer up to 9.400 rpm. The control angles of 124 ° to 182 ° seem to be clearly pleasant to the Polini Box.


Test bench diagram as PDF:  VGL_M244_1_2_POLINI

Test Scooter and Service NEWLINE

The Newline generally shows a different character in terms of power increase at small steering angles than the Elron or the Polini Box.

Similar to the Elron is the rather unimpressed behavior on the changed exhaust control angle. The peak power increases by almost one hp, the maximum torque remains almost identical and the speed range becomes somewhat narrower, as with the Elron, due to the later start of resonance. Even in the second expansion stage, the Newline retains the top position when it comes to torque with 36,7 Nm at 6.137 rpm.


Test bench diagram as PDF:  M244_1_2_NEWLINE

Test Posch Nessie

The Nessie, like the Newline, is intended for moderate control angles, and also shows the clear shift at the start of resonance. Viewed in absolute terms, the Nessie “only” adds 2,5 HP to the top, but in the range between 6.300 rpm and 9.000 rpm it can be clearly seen that the larger outlet angle significantly increases the performance over this range.

Test bench diagram as PDF: M244_1_2_NESSIE

Test Posch Racing Resi

The Racing Resi with its imposing, bulbous appearance already gives the impression of performance and the greed for steering angles. Therefore, the slightly increased outlet angle is not enough to achieve absolute top performance. Here, too, the start of the response is much later. At its peak, the Resi increases by 1,7 HP and this can use the slightly increased exhaust control angle between 7.300 rpm and 10.000 rpm to increase power and torque.


Test bench diagram as PDF: M244_1_2_RAC_RESI

Kingwelle Lakers test

The robust racing exhaust from Lake Constance has already shown on the plugged-in version of the M244 that it is also a good all-rounder. As with all other tested resonance systems, the speed range also shifts in the direction of higher speed, but without the bandwidth being affected. With a band of almost 4.300 rpm, it provides the largest bandwidth in this expansion stage. With 37,8 PS at its peak, the Lakers, at least in this expansion stage, has to admit defeat to the Resi with 37,9 PS - but we are only just warming up on the subject of the steering angle.


Test bench diagram as PDF: M244_1_2 LAKERS

The results of the test bench runs, expansion stage 1_2

Here again the results in tabular form. The best values ​​are highlighted in green for each construction stage

Part 4 is already in progress ...