T-C, the Germans did utilize 'hot cams' with higher overlap, along with higher static comp-ratios in their mills,Tommy Cookers wrote: ↑Sat Aug 19, 2017 1:04 pmcharge distribution problems can be worse with DI or PI than with carburation or similar at the throttle bodyJ.A.W. wrote:.......As BMW found & Bristol belatedly confirmed, radial engines - with their inherently problematic mixture distribution, did gain significant benefit from direct injection.
& Bristol had found that sleeve-valve merits included ( as Ricardo predicted) certain flow dynamics,
which enabled aspects of improved port injection performance, too..
(for the best current appreciation of the practicalities the appropriate forums can be googled)
DI helps in low boost engines by enabling the raising of CR .....
it loses in high boost engines the large saving in supercharger work etc of fuel-evaporation cooling
- which was only efficiently practicable with DI, & worth - in their view, the loss of latent-heat charge-cooling.
& of course, the Bristol sleeve valve cylinder offered yet a greater level of options..
Re: DI &/or PI injector placements, being sans poppet valve-heads to crowd the combustion chamber/plug location,
or obtund the inlet ports..
& by allowing elegant pipe routing for efficacious exhaust efflux vectors - useful both for air-cooling flow, & thrust..
'Flight' shows how well Bristol got its 'power-egg' Hercules set-up sorted, even for their utility 'carthorse' Freighter;
http://www.flightglobal.com/pdfarchive/ ... 00239.html