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Old 02-06-2018, 05:23 PM   #126
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Originally Posted by vicious_fishes View Post
What saturn said. And you want parallel on the EZ30 too.
The EZ30 may have some intricacies I am not familiar with, but it would be difficult to sell me on parallel lines given the potential leaks and what happens if one side has a resistance to flow. See my earlier post regarding parallel lines - they do have a place, but I feel it is far more limited than most would assume.

Generally speaking, parallel lines are best used for stepping a large single feed down to smaller rail feeds.
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Old 02-06-2018, 07:01 PM   #127
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Agreed. Never been a fan of parellel either. Even V8 LSx mototrs run series. I feel parrellel just inceases heat soak prior to injection.
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Old 02-09-2018, 06:49 AM   #128
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Originally Posted by vicious_fishes View Post
What saturn said. And you want parallel on the EZ30 too.
Parallel as in parallel feed? Absolutely, I wouldn't even consider series feed, on anything other than an I4... The set-up I have is -8AN to the FPR with 2x -6AN to the rails. The Mallory FPR I am considering has 2 outlets and a return so I can either cap or bridge the ends of the rails.
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Old 02-09-2018, 07:01 AM   #129
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Agreed. Never been a fan of parellel either. Even V8 LSx mototrs run series. I feel parrellel just inceases heat soak prior to injection.
Sure, I've seen lots of European motors running series; Audi, Mercedes, etc, on their V8 motors. Not sure about the V12 Mercs though (and I have been working on one of those this week tracing a parasitic current draw!), or the biturbo AMG motors, but I'll look the next time we get one in the shop...

Preventing heat soak all comes down to thermal management IMHO; take care of your heat sources and protect your sensitive areas correctly and it should never be an issue.
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Old 02-09-2018, 07:54 AM   #130
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Made some progress on my twin pumper set-up... used a compact 45 degree -8AN adaptor into a V-block with 2x -6AN inlets, one from each pump. By angling the fittings appropriately I was able to get a direct run from the main pump in the original location.

The second pump I'll have to squeeze in as close as possible since there is limited space and the outline cannot be larger than that of the opening in the tank.









That's all for now. But please check out updates on my body restoration thread, some exciting progress has been made there!

https://forums.nasioc.com/forums/sho...1413690&page=7
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Old 02-09-2018, 07:32 PM   #131
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Agreed. Never been a fan of parellel either. Even V8 LSx mototrs run series. I feel parrellel just inceases heat soak prior to injection.
Then, with respect, you don't know what you're talking about. boxer 4's have series, but twin banks with 6+ cylinders should be parallel.
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Old 02-09-2018, 08:44 PM   #132
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Then, with respect, you don't know what you're talking about. boxer 4's have series, but twin banks with 6+ cylinders should be parallel.
Without other qualifying details, this is incorrect.

Fluid transfer doesn't care if your engine is a V- or I- or H- or otherwise-patterned engine... it does, however, try to overcome a blockage in a series system while giving up and taking the path of least resistance in a parallel system.

The only time a system *should be* parallel is when you're trying to supply two smaller rails with a single supply (i.e. -8AN into dual -6AN rails).
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Old 02-10-2018, 09:28 AM   #133
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After reading this thread, having a think and mulling over the ideas presented here, if I was to be starting my project now or designing an adequate fuel system for a future project, I would simply run 2 pumps with separate lines forward to each rail and have their own FPR and return lines to the tank...
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Old 02-10-2018, 09:59 AM   #134
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After reading this thread, having a think and mulling over the ideas presented here, if I was to be starting my project now or designing an adequate fuel system for a future project, I would simply run 2 pumps with separate lines forward to each rail and have their own FPR and return lines to the tank...
What do you feel the benefits are doing it that way instead of just running dual staged pumps with a single feed to both rails (series or parallel)? Definitely not the cheapest way to do it.
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Old 02-10-2018, 10:02 AM   #135
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Agreed. Never been a fan of parellel either. Even V8 LSx mototrs run series. I feel parrellel just inceases heat soak prior to injection.
Isn't that a returnless system? If so not the same animal.
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Old 02-10-2018, 02:50 PM   #136
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Originally Posted by Legacy_H6TT View Post
After reading this thread, having a think and mulling over the ideas presented here, if I was to be starting my project now or designing an adequate fuel system for a future project, I would simply run 2 pumps with separate lines forward to each rail and have their own FPR and return lines to the tank...
Bad idea - you're counting on two independent systems functioning identically throughout the entire operating range. If you do this, you're essentially making a NEED for per cylinder (or per bank, at a minimum) AFR measurement and tuning.

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Isn't that a returnless system? If so not the same animal.
The 2008+ system is odd enough... I didn't even bother talking about returnless...
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Old 02-10-2018, 10:40 PM   #137
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Legacy_H6TT, just run in series. Let's go with it's good enough for modern NASCAR engines...if you think NASCAR engines are low tech, you're far off.

However the argument of time in the rail to heat up that came up, I disagree with that. You have a given flow rate of fuel and a given consumption rate. You're going to move the same mass in the same time...within negligible difference.
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Old 02-11-2018, 08:35 AM   #138
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Legacy_H6TT, just run in series. Let's go with it's good enough for modern NASCAR engines...if you think NASCAR engines are low tech, you're far off.

However the argument of time in the rail to heat up that came up, I disagree with that. You have a given flow rate of fuel and a given consumption rate. You're going to move the same mass in the same time...within negligible difference.
I meant if you split the feed into two parrellel lines that the fuel would move across the engine half as fast that's all.
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Old 02-11-2018, 02:50 PM   #139
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I meant if you split the feed into two parrellel lines that the fuel would move across the engine half as fast that's all.
Heating caused by this dwell time is still inconsequential to the pump heating the fluid over and over and over...

This is actually one theoretical advantage to returnless systems - the fuel in the tank stays cool, is only heated once, and doesn't have enough dwell time near the motor to actually get all that hot.

By heating the returned fuel in a traditional return system, the fluid input to the pump becomes warmer over the run-time of the motor (both from the pump, and to a lesser extent, the lines/rails) and you end up with a wider temperature delta.
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Old 02-11-2018, 11:01 PM   #140
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Exactly. I guess my point of time didn't quite drive it home.
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Old 02-12-2018, 09:13 AM   #141
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so you guys are saying that the fuel pump introduces more heat into the fuel than sitting in aluminum rails on top of the engine?

I ran some quick numbers.

At Idle, my car consumes about 50cc/min of fuel through 80cc of rails and the line that runs between them. If it were at returnless system , that fuel would spend 96 second on top of my engine. It gets a lot faster though at cruise. I consume about 396cc/min cruising, at 2500 rpm the fuel is gone in 12 seconds.

But since the rails are in a return type system in series, fuel is flushed through across the engine much faster, probably spending less than 5 seconds above then engine

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Old 02-12-2018, 05:06 PM   #142
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At Idle, my car consumes about 50cc/min of fuel through 80cc of rails and the line that runs between them. If it were at returnless system , that fuel would spend 96 second on top of my engine. It gets a lot faster though at cruise. I consume about 396cc/min cruising, at 2500 rpm the fuel is gone in 12 seconds.
I'm seeing about 35 cc/min at idle on my logs, but how are you calculating rail volume? 80 cc seems excessive - I'm getting estimates of about ~25 cc with a -6AN standard I.D. of 3/8". I omitted line volume as the rubber is a reasonably good insulator.

Even so, if you only consider idle, I can name plenty of other parts that get excessively hot when you're just sitting there - consider the most common scenario here and fuel dwell time in the rails is nothing in both scenarios. The difference will still be starting with a lower source temp. in returnless.

Don't get me wrong - I still would never use returnless in a performance scenario... the pressure control just isn't precise enough.
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Old 02-13-2018, 02:14 AM   #143
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All this talk about fuel heating is rather interesting, I had never really considered it as a thermal management concern before. This gets me onto thermal management in general; if you're optimising your cooling, intake temps, oil and other essential fluid temps, then if it is an issue then you probably ought to be optimising (or at least controlling) your fuel temps. It's no more difficult to run a fuel cooler than it is a fuel filter or oil cooler. Sure, you can do the analysis to try to determine how much you need to lower your temps by, so that you can calculate the correct cooler size, and then you are free to run whatever fuel system (series, returnless, etc) that is going to meet your power requirements.

As for my thought about running a true parallel system forward, just an idea I guess, but someone a while back told me that V and Boxer engines can be somewhat treated as 2 separate engines; I even considered making separate intake plenums for my EZ30 (complete with secondary injectors to back up the ones in the heads) so that I could feed each turbo into its own intercooler and intake, with independent exhausts (no x-over or Y-pipe) to make truly separate engines joined only by the crankshaft... again, just an idea, and the 2 fuel lines kinda fits with the concept, although I am sure there will be factors to consider if actually implementing a system like this, such as inline fuel flow measurement and electronic pump control.
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Old 02-13-2018, 02:17 AM   #144
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At any rate, Aeroquip provide this neat chart to work out fluid velocity for any desired flow rate and hose ID, helping to identify and develop your pumping requirements and setting an appropriate pressure....

https://drive.google.com/file/d/1Fl9...ew?usp=sharing
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Old 02-13-2018, 02:22 AM   #145
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Originally Posted by Homemade WRX View Post
Legacy_H6TT, just run in series. Let's go with it's good enough for modern NASCAR engines...if you think NASCAR engines are low tech, you're far off.

Haha, yeah I know NASCAR motors aren't low tech; flat plane cranks, EFI, 9000rpm+ redline! And seeing where you're located you have to appreciate my love of the sport #doitfordale
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Old 02-13-2018, 03:17 AM   #146
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Passive fuel cooling isn't uncommon, but running a pump within it's range of efficiency is still a better starting point. It's exactly the same as trying to get a turbocharger to work harder than it was designed - it starts adding massive amounts of waste heat into the system. Sure, you can buy a larger intercooler at this point... but starting with a better matched turbo and then cooling the air further with a good intercooler will leave you with the better end result.

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Haha, yeah I know NASCAR motors aren't low tech; flat plane cranks, EFI, 9000rpm+ redline! And seeing where you're located you have to appreciate my love of the sport #doitfordale
Decades ago, one of the first guys that taught me real in-depth knowledge about engine rebuilds had experience with NASCAR engine development. Back when the engines were 'low tech' they were still doing very high tech R&D on the dyno, then taking that knowledge and dumbing it down to meet spec. rules.

For instance - per cylinder fuel injection tuning was done on the engine dyno and then rocker arm dimensions were changed on a per cylinder basis to allow the per cylinder optimization to be realized on the (at the time) carburated motor.
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Old 02-13-2018, 09:02 AM   #147
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All this talk about fuel heating is rather interesting, I had never really considered it as a thermal management concern before. This gets me onto thermal management in general; if you're optimising your cooling, intake temps, oil and other essential fluid temps, then if it is an issue then you probably ought to be optimising (or at least controlling) your fuel temps. It's no more difficult to run a fuel cooler than it is a fuel filter or oil cooler. Sure, you can do the analysis to try to determine how much you need to lower your temps by, so that you can calculate the correct cooler size, and then you are free to run whatever fuel system (series, returnless, etc) that is going to meet your power requirements.

As for my thought about running a true parallel system forward, just an idea I guess, but someone a while back told me that V and Boxer engines can be somewhat treated as 2 separate engines; I even considered making separate intake plenums for my EZ30 (complete with secondary injectors to back up the ones in the heads) so that I could feed each turbo into its own intercooler and intake, with independent exhausts (no x-over or Y-pipe) to make truly separate engines joined only by the crankshaft... again, just an idea, and the 2 fuel lines kinda fits with the concept, although I am sure there will be factors to consider if actually implementing a system like this, such as inline fuel flow measurement and electronic pump control.
With everyone running flex setups now, the sensors have fuel temp sensors built in. Of course Cobb tells people to run them on the pressure side so your not seeing what the temp is at injection but it should be close. I never paid too much attention to my temps. Only ever looked at E% after pumping and then quit watching. I never noticed it being much more than ambient temp though, maybe 20 degrees over after a long drive to the E85 station. My sensor is after the regulator
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Old 02-13-2018, 10:14 AM   #148
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Heating caused by this dwell time is still inconsequential to the pump heating the fluid over and over and over...

This is actually one theoretical advantage to returnless systems - the fuel in the tank stays cool, is only heated once, and doesn't have enough dwell time near the motor to actually get all that hot.

By heating the returned fuel in a traditional return system, the fluid input to the pump becomes warmer over the run-time of the motor (both from the pump, and to a lesser extent, the lines/rails) and you end up with a wider temperature delta.
It depends how its configured.. You can return the fuel and cool it you know all while maintaining a traditional return system.
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Old 02-13-2018, 10:17 AM   #149
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Originally Posted by Legacy_H6TT View Post
After reading this thread, having a think and mulling over the ideas presented here, if I was to be starting my project now or designing an adequate fuel system for a future project, I would simply run 2 pumps with separate lines forward to each rail and have their own FPR and return lines to the tank...
You can do that for sure. But I wouldnt run then to each rail. I'd run 2 lines to one. Then to your choice serues or parrallel. This will take some pressure off the pump also allowing for slightly cooler temps. You can also get the same results with a larger fuel line.
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Old 02-13-2018, 02:32 PM   #150
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It depends how its configured.. You can return the fuel and cool it you know all while maintaining a traditional return system.
I was mainly referring to factory systems with the return/returnless comparison. Most cite the cost savings of only one line as the reason OEMs go returnless, but the reduced emissions and potential hair better fuel economy from cooler fuel temps is probably another reason.
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