I've got a job to look into and would appreciate anyone being able to share practical knowledge/experience The project involves a squirt of 'camping gas' (butane/propane mix - LPG) from a canister into a cylinder. This is then ignited by a spark plug or piezo. The explosion drives a piston very forcibly, stretching the return spring which brings it back to its rest position, mostly venting the exhaust as it does. It's similar to a gas nail gun (like the Paslode), only bigger. Operation is not more often than once per minute. It has been used in an unrefined version, proving the principle, and now I've got it to improve the performance. On improvement for example is linking temperature and pressure to injection time to try and get a reliable and consistent bang, and there'll be a PIC to do this amongst other things The first thing I need to do is find out some characteristics of fuel injection valves. A Google for fuel injector driver brings up for example these two (1) http://www.bgsoflex.com/FI_tester_doc.pdf (2) http://bakengineering.com/page6.html The figures in (1) are in the general ballpark of activation times based on rough rpm calculations I did. (2) indicates that 30V is being applied "The POWER-DRIVER outperforms other peak-hold fuel injector driver modules! While other modules use 12 Volts (supplied by the battery) to drive the injectors to 4 Amperes, ours are voltage-boosted and deliver 30V, for significantly faster fuel injector response time" Using over-voltage is something I'd already considered to improve reaction time, so it's good to see that it's actually done in practice. I'm assuming that something like a low-side FET is used I've not yet got the pressure figures for a typical gas canister (although 800psi has been suggested) so the actual activation time range for a valve in this application is an uncertainty I'm still Googling but if anyone has something they'd like to share it would be appreciated TIA -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist