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Previous PostTech Posts > Performance Tips & Tricks > Shower injectors and Velocity stacks
Steve Leeson
North Yorkshire,
United Kingdom

Posts: 673

09 Mar 2016 18:33
Sadly chap its doubtful the engine would stand an extra 2000rpm that would take Mean piston speed* up to 29.25 MPS*& 25 MPS*is generally regarded as around the limit in a reciprocating engine, our Daytona’s have quite a long stroke (for a sports triple - Ducati‘s 916 twin has a stroke of 66mm) & are already pretty much near the limit at standard max rpm:
Daytona 955
Engine Stroke: 65mm
Engine RPM: 11.500
MPS*: 24.917

…… raising the rpm limit to get “more bangs” is not much of an option for us - to get more power, increasing the gas flow into the engine & improving the atomization of the fuel inside the combustion chamber to get a “bigger bang” is another way to make more power, reducing frictional & other losses is also a way we can go to get more power to the rear wheel

My question regarding shower injectors mounted above the velocity stacks is because from what I’ve been reading/researching, they work better at high flow rates, with improved fuel atomization at high rpm, the disadvantage of single (primary) Injectors positioned close to the valves at high rpm (like the 955) is that with the rise in air/gas speed, the fuel does not have time to mix with the air as efficiently as high (secondary) mounted injectors, also each model of injector is only capable of flowing a certain amount of fuel, apparently many production bikes don’t have much spare capacity in the injectors, they are near 100% duty cycle & the injector is permanently open at full rpm and are unable to deliver more fuel no matter what the ECU tells it, injector’s reliability can suffer too, being permanently energised the coil inside the injector gets really hot & can burn out.

An Aprilia RSV1000 fitted with Smaltmoto Shower-Injection & velocity stacks for 57mm Throttle body’s gains 3-5 hp through the rev range

It would be interesting to find out if there are any decent gains to be had on the 955 :smile:

*MPS = The mean piston speed is the average speed of the piston in a reciprocating engine
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