Scott Posted July 8, 2011 Share Posted July 8, 2011 I'm buying an Aeromotive FPR and during the transaction I was asked what fittings I wanted. I had the setup one way in my head but a different method of setting it up was suggested. I'm just looking for information as to why one setup would be more beneficial to the other. In my head they both seem to do the same thing but obviously I have no experience here. Please excuse the crude drawings.... Yellow is fuel pressure, green is return and blue is the twin feed rail. Quote Link to comment Share on other sites More sharing options...
Wez Posted July 8, 2011 Share Posted July 8, 2011 FPR between the rail return and tank, it is not connected to the feeds in anyway. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 FPR between the rail return and tank, it is not connected to the feeds in anyway. Is this your opinion though Wez? Any reasoning behind it? I started the thread to get an understanding of why. Surely the Aeromotive FPRs have an input and an output, along with a drain and a gauge ref point, for a reason? Quote Link to comment Share on other sites More sharing options...
hodge Posted July 8, 2011 Share Posted July 8, 2011 Double post, bloody iPhone lol. Quote Link to comment Share on other sites More sharing options...
hodge Posted July 8, 2011 Share Posted July 8, 2011 If your having a duel feed rail Scott, your feed lines go direct to that not connecting to the FPR at all as Wez says. There should be another take off on the rail which goes to the regulators side port and then the bottom port goes to the return line. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 If your having a duel feed rail Scott, your feed lines go direct to that not connecting to the FPR at all as Wez says. There should be another take off on the rail which goes to the regulators side port and then the bottom port goes to the return line. I understand that this is the way you guys have done it. I still don't have any reasons as to why though bud. You are both telling me to do it your way without giving me any understanding of why. I see no difference, regarding the pressure in the rail, with either setup. If there was a restriction between the "in" and the "out" ports I could understand why but as far as I know there isn't, the restriction is put on the fuel return. Quote Link to comment Share on other sites More sharing options...
Wez Posted July 8, 2011 Share Posted July 8, 2011 You could go with the tried/tested/documented method or if you feel you know better then test it and post the results Quote Link to comment Share on other sites More sharing options...
hodge Posted July 8, 2011 Share Posted July 8, 2011 I'm going to be honest here Scott, I don't have a clue. The stock fuel system is setup that was so the regulator is on the return line so that's the way I set mine up too. Maybe and just maybe, if you put it in the feed line you will only reduce pressure in the feed line after the FPR which will restrict flow. Don't you want as much flow as possible but then regulate the pressure in the rail by the speed it returns back to the tank. Quote Link to comment Share on other sites More sharing options...
David P Posted July 8, 2011 Share Posted July 8, 2011 (edited) The FPR is located after the rail because the injectors are releasing pressure and the FPR maintains correct working pressure in rail. Mounting FPR before rail will not allow for this and starve fuel. Edited July 8, 2011 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 You could go with the tried/tested/documented method or if you feel you know better then test it and post the results I don't feel that I know better, but to put it bluntly I don't think you guys know either as you can't give me any reason as to why. I like to have an understanding of tasks before I undertake them, and one thing I certainly won't do is install something a certain way blindly because everyone else does it that way. In this particular case I do know a little bit of what I'm talking about as I work with gas, fluids, regulators, pressure testing equipment etc in work. This is the reason for my query, in my understanding the above circuits will do exactly the same thing, I'm looking for insight as to why that might not be the case... maybe something i;ve missed. Quote Link to comment Share on other sites More sharing options...
hodge Posted July 8, 2011 Share Posted July 8, 2011 The FPR is located after the rail because the injectors release pressure and the FPR maintains correct working pressure in rail. Mounting FPR before rail will starve the fuel. That's what I ment. But didn't know how to explain it lol. Quote Link to comment Share on other sites More sharing options...
Wez Posted July 8, 2011 Share Posted July 8, 2011 Have you tried google Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 (edited) The FPR is located after the rail because the injectors are releasing pressure and the FPR maintains correct working pressure in rail. Mounting FPR before rail will not allow for this and starve fuel. I don't see that making any difference given how the FPR works. A pressure drop anywhere in the line will effect pressure throughout the system instantly. It makes no difference where the relief or the restriction is. A drop in pressure in the rail due to the injectors working will see the same pressure drop at the fuel filter and the same pressure drop at the FPR. You are correct in thinking that a regulator before the fuel line would be a bad idea, this isn't the case though as.... far as I can see anyway. The restriction, as I've said, is put on the return line so the actual regulation is on the return line, not the fuel in or out. Edited July 8, 2011 by Scott (see edit history) Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 Have you tried google Yeah, that's where I found out about the aeromotive ports. Basically everyone blocks off the "In" port of the aeromotive fuel regulator for no aparent reason. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 8, 2011 Share Posted July 8, 2011 Looking at the diagrams, i can see it making no difference whatsoever, the FPR operates just the same either way, i can't see it affecting flow or pressure. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 Looking at the diagrams, i can see it making no difference whatsoever, the FPR operates just the same either way, i can't see it affecting flow or pressure. Thankyou, either I'm not nuts or we both are Quote Link to comment Share on other sites More sharing options...
David P Posted July 8, 2011 Share Posted July 8, 2011 The FPR is located after the rail because the injectors are releasing pressure and the FPR maintains correct working pressure in rail. Mounting FPR before rail will not allow for this and starve fuel. Thankyou, either I'm not nuts or we both are Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 You didn't read my reply, you don't understand how the FPR works either given your reply Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted July 8, 2011 Share Posted July 8, 2011 Surely the conventional setup would be better prepared to cope with sudden pressure drops as theres a constant flow through the rail and injectors, the first diagram just provides a head of pressure, theres no flow as such, only created by consumption of the engine. Secondly with no flow through the rail and a hot engine that fuel is gonna get warm. Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 Surely the conventional setup would be better prepared to cope with sudden pressure drops as theres a constant flow through the rail and injectors, the first diagram just provides a head of pressure, theres no flow as such, only created by consumption of the engine. Secondly with no flow through the rail and a hot engine that fuel is gonna get warm. I don't agree with the head of pressure, as they would both create the same pressure if the "in" to "out" ports are unrestricted, but I agree that there would be no flow through the rail which after a hard pull kicking down to idle will end up with a hot rail and hot fuel (not good). Conventional setup it is, thanks for the explanation Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted July 8, 2011 Share Posted July 8, 2011 I don't agree with the head of pressure, as they would both create the same pressure if the "in" to "out" ports are unrestricted I know the pressure would be the same mate, thats not in question, the flow rate was my point, its just a loop of pressurised fuel, thats what I was getting at Quote Link to comment Share on other sites More sharing options...
Scott Posted July 8, 2011 Author Share Posted July 8, 2011 I know the pressure would be the same mate, thats not in question, the flow rate was my point, its just a loop of pressurised fuel, thats what I was getting at Sorry, what I meant was that there would be no difference in pressure drops with either setup. That's the part I didn't agree with the direction of flow or lack of it won't make any difference to how quickly the rail is re-pressurised, that's going to be down to the pump as long as the "in" and "out" ports were unrestricted. Regardless, I agree that there will be no flow of fuel through the rail, the only fuel flowing into the rail will be the fuel that is being used by the injectors. At idle this won't be a lot and if the injectors & rail are hot this will heat up the fuel very quickly which obviously won't be good. Overheating the injectors alone can be really bad. Good information for anyone wanting to understand why the conventional method is used Quote Link to comment Share on other sites More sharing options...
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