Mike-e Posted May 28, 2008 Share Posted May 28, 2008 Quote Link to comment Share on other sites More sharing options...
lowlancer Posted May 28, 2008 Share Posted May 28, 2008 The best part was the spelling of "surprise" Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted May 29, 2008 Share Posted May 29, 2008 I don't know if this has been mentioned during the shit fiest but for those that don't know a regulator is there to keep the pressure difference between the injectors and the inlet manifold consistant so that when the injector is fired under any load condition for x miliseconds y amount of fuel comes out. If the reg wasn't referrenced to the manifold pressure firing the injector for x milisecs would give more fuel at idle than it would at WOT. Generally the difference between the injectors and inlet manifold is 45 psi. Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted May 29, 2008 Share Posted May 29, 2008 Excellent, except wtf is a rising rate regulator doing within 100 feet of an engine??? Are you going to all this trouble and then hacking your fuel supply? Fixed rate of 1:1 and engine management of your choice is the way to go. Fred. Like Fred said fixed rate with programable ECU is the way to go. Rising rate FPR's came about as a cheap fix to get more fuel in under boost with out reprograming the ECU. Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted May 29, 2008 Author Share Posted May 29, 2008 um ok i am under the impression that you want the fuel pressure to increase under boost. eg if i ran 50psi boost and my fuel pressure was 50psi then no fuel would be injected becos theres no pressure difference? please correct me if im wrong lol so say i ran a fixd pressure of 50psi and ran 25psi boost wouldnt less fuel be injected at any given duty cycle under boost than not under boost. i realise thats not a real life example but i hope you can see what im tryn to say lol. ding ding haha Quote Link to comment Share on other sites More sharing options...
Guest vvega Posted May 29, 2008 Share Posted May 29, 2008 arh i see a fuel pressure regulator compensates for the manifold pressure differential be it boost or vacuum.... at a ratio of 1:1 a rising rate one multiply the compensation factor on boost by whatever its set to do so it might be a 1:2 ratio so for every 1 psi of boost it gives you 2 psi of fuel pressure i realize as soon as you read this you will be sweet...its probably just calling something the wrong name Quote Link to comment Share on other sites More sharing options...
forced Posted May 29, 2008 Share Posted May 29, 2008 If you look at a flowchart for a walbro pump (purely as an examle) you'll see that one which flows 60GPH (US gallons) at 35PSI (idle pressure) will flow 50GPH at 60PSI (15 pounds boost). Sure it's a difference but not a great deal when looking at overall fuel flow. What it tells you is that at idle there'll be about 59.9GPH going through the regulator and at WOT, max rpm, there'll be bugger all,most going through the injectors, depending on how much power you're making. Quote Link to comment Share on other sites More sharing options...
fishtailfred Posted May 29, 2008 Share Posted May 29, 2008 um ok i am under the impression that you want the fuel pressure to increase under boost.eg if i ran 50psi boost and my fuel pressure was 50psi then no fuel would be injected becos theres no pressure difference? please correct me if im wrong lol so say i ran a fixd pressure of 50psi and ran 25psi boost wouldnt less fuel be injected at any given duty cycle under boost than not under boost. i realise thats not a real life example but i hope you can see what im tryn to say lol. ding ding haha Like vvega said, you get 1psi boost, you get base pressure + 1psi of fuel pressure and the difference across the tip of the injector is always constant at 40 - 45psi (depending on which manufacturer). So at 25psi with base of 50 and normal 1:1 non rising rate you get 75psi of rail to atmo pressure and 50psi difference across the injector. Conversely if you have "10psi vacuum" in your inlet at idle, you get 40 in the rail relative to the world, but still 50 across the injector. Let me quote something someone just said about rising rate totally independently of this discussion : First part is sarcastic! : (06:50:27) Rob : I'm going back to RRFPR(06:50:42) Rob : and boost based timing device (06:50:45) Rob : (06:50:55) Rob : like I had on my sc (06:51:19) Fred: lol (06:51:23) Fred: rising rate ftl (06:53:42) Rob : yeah (06:53:56) Rob : my car used to look like it was coal burning at the exhaust pipe (06:53:59) Rob : what a mess Fred. Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted May 30, 2008 Share Posted May 30, 2008 um ok i am under the impression that you want the fuel pressure to increase under boost. The fuel rail pressure follows the manifold pressure, boost the pressure rises vac the pressure drops. The pressure difference between the inlet manifold and the injectors stays the same. Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted May 30, 2008 Author Share Posted May 30, 2008 oh yip i see sweet as, but whats so bad about using a rising rate regulator? its got a link and getting dyno tuned anyway so surely it wont matter? if anything it will allow my injectors to flow more than the rating. . . . Quote Link to comment Share on other sites More sharing options...
Ke36 Posted May 30, 2008 Share Posted May 30, 2008 only read last page cos im lazy/dont know much/this is a pointless post but... 1:1 common aftermarket regs such as sard, malpassi etc are commonly reffered (wrongly) to as "rising rate" they do also however do actuall rising rate ones aswell, i think sard do a 1:1.25 or 1:1.5 Quote Link to comment Share on other sites More sharing options...
fishtailfred Posted May 30, 2008 Share Posted May 30, 2008 oh yip i see sweet as, but whats so bad about using a rising rate regulator? its got a link and getting dyno tuned anyway so surely it wont matter?if anything it will allow my injectors to flow more than the rating. . . . Injector lock, pump stall, reduced pump flow due to excess pressure etc. If you are pushing 25 with base of 50 and use a 1:2 your pump has to flow full engine fuel demand at 100psi. Only the 044 can manage that, all the other pumps suck balls at high pressure. http://www.diyefi.org/forum/viewtopic.php?f=24&t=47 pump flow pics are in there. Worst though : difficulty and unpredictability of fuel flow will probably make tuning a bitch. Fred. Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted May 30, 2008 Author Share Posted May 30, 2008 why the fuck would the pump stall? at max boost the motor will be using shit loads of fuel Quote Link to comment Share on other sites More sharing options...
Guest vvega Posted May 30, 2008 Share Posted May 30, 2008 Worst though : difficulty and unpredictability of fuel flow will probably make tuning a bitch. Fred. because boost is constant then fuel presure will also be constant while it may make for funny tunign numbers its perfectly tunable and would be fine as has been said its not the perfect solution but if his pump can do the numbers ...it will be fine just need a tuner than can tube buy a/fs and not one that looks for pattern's eke_zetec_RWD yes your injectors will flow more...but you will need a good pump i have a 1:1 fpr kicking around if you need to change...ill look at the cost and flick it to you for my cost on it...hell i may even have 2 Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted May 30, 2008 Author Share Posted May 30, 2008 ok cheers man, and yea all tuning is done on hub dyno wif all the equipment for everything so theres no gessing involved. so yea the fuel numbers will be a lil different to a 1:1 but will result in the same tune at the end of the day as far a a/f ratios go. Quote Link to comment Share on other sites More sharing options...
fishtailfred Posted June 4, 2008 Share Posted June 4, 2008 why the fuck would the pump stall? at max boost the motor will be using shit loads of fuel You are right, it won't stall under most conditions, but it's flow will be heavily reduced. In the event that you have a batch fire system it WILL stall if no injector is open at some given time and pressure has been pushed up too high. Same goes if you have sufficient pressure and sequential injection with short pulsewidths that don't overlap. Not good for the pump to be stopping and starting like that... Also, do you really expect your injectors to open predictably at 75psi tip cross pressure? I wouldnt. At the VERY LEAST they are opening a LOT slower quite possibly reducing fuel flow overall because of the linear rate of flow reduction with opening time and the non linear rate of flow increase with pressure. Obviously some higher pressure will net gains, but if you have a standalone you are just shooting your foot to use rising rate. sure, run 60psi base pressure to get a little more flow from the injectors, but don't use rising rate... Quote Link to comment Share on other sites More sharing options...
forced Posted June 4, 2008 Share Posted June 4, 2008 The pump won't stall at all, the fuel will flow through the regulator to maintain correct pressure. Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 5, 2008 Share Posted June 5, 2008 The pump won't stall at all, the fuel will flow through the regulator to maintain correct pressure. It will stall at some point becase the pump wont make enough pressure to over come the regulator spring and boost pressure. A rising rate FPR will hit this pressure faster than a 1:1. What this pressure is depends on the pump Quote Link to comment Share on other sites More sharing options...
Steelies Posted June 5, 2008 Share Posted June 5, 2008 Q: doesnt the reg act as a relief to ensure the pump doesnt stall? Quote Link to comment Share on other sites More sharing options...
nismo.capri Posted June 5, 2008 Share Posted June 5, 2008 Q: doesnt the reg act as a relief to ensure the pump doesnt stall? Nope it acts as a restriction to build up pressure. When it reaches the set pressure the FPR cracks open to relieve the excess pressure. Boost is ported to the spring side of the diaphram to help the spring hold closed the FPR closed which rases the fuel pressure. Quote Link to comment Share on other sites More sharing options...
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