Does fuel pressure effect the heat generated by the combustion process? If so, how?

I've seen several remarks that lead me to believe that higher fuel pressures increase the combustion heat. The comment always refer to increasing injector size. Something like "blah blah bigger injectors so I can lower the fuel pressure and run cooler".

I'm trying to plan for an 8 injector setup. It'll use the same controller that Corbin has in his writeup. I haven't recieved the controller yet, but it appears as though it has enough control so that I'll be able to set the fuel pressure to whatever I want to. More specifically, if there is not enough fuel pressure for the primary injectors to fully compensate for the engine's fuel requirements - it looks like you can just add more fuel from the secondary rail to make up the difference. So I suppose what I'd really like to know, is that if pressure DOES effect combustion heat - what is the optimum fuel pressure(for EFI)?


ride__________95 Eclipse RS : 5 speed
power________Field SFC Hyper-R : Gude cams : Jeep TB : AFX UDP : ram air : test pipe : GST catback
suspention___Hurricane F/R lower strut ties : BOMZ F/R upper strut bars : ES inserts
sound________Kenwood KDC 5000 : Audiovox 8" sub toob : Xplod 222
shizzle_______AutoCommand remote start : dual air horns : Caspers o2 simulator(rear)
incomming___Bosal header(maybe), 14b turbosystem(eventually)
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

>Does fuel pressure effect the heat generated by the
>combustion process? If so, how?

As far as I know, no it does not, at least fuel pressure alone.
>
>I've seen several remarks that lead me to believe that
>higher fuel pressures increase the combustion heat. The
>comment always refer to increasing injector size. Something
>like "blah blah bigger injectors so I can lower the fuel
>pressure and run cooler".


We say this because we want to run more fuel with each duty cycle of the injector. When we push more fuel pressure through an already maxed out injector, we are pushing the limits of the injector, and run the risk of it closing shut, or not being able to spray fuel because of the intense pressure behind it. With larger injectors, we can run a lower duty cycle, and get better fuel flow, with running a more reasonable fuel pressure. I've heard that running an injector over 80% duty cycle, isnt good, and fuel delivery issues can arise. Being able to run more fuel into the engine using larger injectors keeps the engine cooler, eg. EGT's anyway, since more fuel cools combustion.
>
>I'm trying to plan for an 8 injector setup. It'll use the
>same controller that Corbin has in his writeup. I haven't
>recieved the controller yet, but it appears as though it has
>enough control so that I'll be able to set the fuel pressure
>to whatever I want to. More specifically, if there is not
>enough fuel pressure for the primary injectors to fully
>compensate for the engine's fuel requirements - it looks
>like you can just add more fuel from the secondary rail to
>make up the difference. So I suppose what I'd really like to
>know, is that if pressure DOES effect combustion heat - what
>is the optimum fuel pressure(for EFI)?

Most of the info i have come upon recomends around 35-45 psi minimum fuel pressure on fuel injectors for proper fuel atomization. Well i run as little as 20 psi when i let off the gas in gear, and the motor runs perfect. I'm pushing the limits of low pressure though..
>

Thanks man :thumbsup


ride__________95 Eclipse RS : 5 speed
power________Field SFC Hyper-R : Gude cams : Jeep TB : AFX UDP : ram air : test pipe : GST catback
suspention___Hurricane F/R lower strut ties : BOMZ F/R upper strut bars : ES inserts
sound________Kenwood KDC 5000 : Audiovox 8" sub toob : Xplod 222
shizzle_______AutoCommand remote start : dual air horns : Caspers o2 simulator(rear)
incomming___Bosal header(maybe), 14b turbosystem(eventually)
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html