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Discussion Starter #1 (Edited)
I had posted a bit about this in another thread, but have been getting several questions. This is Smaay's fuel rail system, and it's a replacement for the stock fuel rail. It's a high quality piece, and for $220 delivered, IMO a great value. (No, I'm not getting commissions on this!).

Benefits of his fuel rail:

- This rail is fed from the center (vs end), which allows better fuel distribution/pressure to all four injectors. This is especially important in cars with higher fuel demands, in particular, forced injection.

- Each end of the rail has a tap to facilitate the addition of a fuel gauge, return system, nitrous feed, test port, etc. (see the blue caps)

- You can easily add an additional fuel filter. Edit: OE filter is tucked away inside the fuel tank. Note this is not included with his kit. In the last picture, you'll see where I've added. I bought the full-flow filter and coupler from Summit Racing, PNs: EAR-915106ERL and SUM-230100.

- It's simple to install, maybe about an hour or so, and it's built like a tank.

More...This fuel rail is also a stage 1, if you will, of his full return system, which I plan to install as a winter project. Ronin was the first to try/test the return system on an Elise, and is very happy. Smaay has sold these kits to lots of owners on NewCelica too.

So, why a return system? Here is a good explanation from Griffin off of MM:

It enables the use of a 1:1 fuel pressure regulator. The factory system is spring regulater in tank to about 45-47 PSI. The problem is the higher you boost the lower the pressure differential gets between your intake manifodl pressure and your fuel pressure. For example:

In a NA application as long as the fuel system had 45 PSI the car always has 45 PSI effective pressure as the pressure in the intake never significantly exceeds 0 PSI

In a turbo application with static fuel pressure the effective fuel pressure is constantly reduced as the intake manifold pressure goes up. At 5 PSI your 45 PSI of fuel pressure has an effective PSI of 40. AT 15 PSI intake pressure your effective PSI is only 30 PSI. AT 20 PSI of boost your intake pressure goes down to only 25 PSI effective. If you dont do anything about that you wind up with a set of HUGE injectors that don't work well at idle and are still close to maxed out at relatively low power levels.

Switchign to a system with a 1:1 regulator and return system is a much more effective way to deal with a boosted car. The 1:1 regulator ncreases fuel pressure by 1 PSI for every PSI increase in manifold pressure resulting in a constant pressure differential between intake and fuel system. For example:

At idle (0 PSI) system is at 45 PSI fuel pressure 45 psi effective pressure (or whatever you set it to)'
at 10 PSI intake pressure fuel system goes to 55 PSI fuel pressure which is 45 PSI effective pressure
at 20 PSI system goes to 65 PSI fuel pressure which is 45 PSI effective pressure

 

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Very nice Dave
Is there a tap off the intake to the regulator
 

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actually there is a fuel filter in the tank. not just the sock that you see sticking out of the bottom of fuel pump.



in this picture you can see the sock on the bottom of the fuel pump. the filter is actually enclosed in the pump assembly.



Dave just took an extra step by adding another filter in line which is totally ok.
 

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What you are referring to as a 1:1 regulator is a rising rate regulator. In my last supercharged audi, this was actually detrimental to performance and tune. Having a fixed rate FPR worked out much better.
 

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®ob said:
What you are referring to as a 1:1 regulator is a rising rate regulator. In my last supercharged audi, this was actually detrimental to performance and tune. Having a fixed rate FPR worked out much better.
Also known as an AFPR (Adjustable fuel pressure regulator.)
 

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Dave, i wonder how many times you have painted your engine trim?

BTW, i like the current one the most!:up:
 

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Dave, where is the regulator and return line. I have used regulators that tapped into the intake and adjusted the pressure based on manifold pressure.
 

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Discussion Starter #9 (Edited)
uglyduck said:
Dave, where is the regulator and return line. I have used regulators that tapped into the intake and adjusted the pressure based on manifold pressure.
This is just the first 'phase'. The return system is my winter project. Some more info here: http://www.newcelica.org/forums/showthread.php?t=242414&highlight=smaay+fuel+return
Bleu Omdurman said:
Dave, i wonder how many times you have painted your engine trim?
BTW, i like the current one the most!:up:
If you mean the letters on the cover, my daughter just painted it for the first time last week. Welcome back to the states!
 

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very cool, made one for my supercharged 02, and never thaught of it for my FI package in the Elise. It does exactly what Dave says, whereby providing a ample consistant fuel delivery accross all injectors.
 

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i would expect that, in a system such as the ECU we have, the nonlinearities can be/are dialed out in the calibration so the add-ons may not be needed.

with the small pressures involved with carburetors, a rising rate regulator sure does insure that fuel starvation doesn't occur.
i had a lot of fun playing with maserati biturbos.
 

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Dave,

I am going to put mine on tomorrow, how did you get that fuel line clip apart down by the windshield washer tank? Does it just kind of pry apart, or is there a trick? I guess the stock clip is not reused, going by your pictures.
 

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Discussion Starter #16
Dave,

I am going to put mine on tomorrow, how did you get that fuel line clip apart down by the windshield washer tank? Does it just kind of pry apart, or is there a trick? I guess the stock clip is not reused, going by your pictures.
The clip will unsnap about halfway, no need to completely remove. Then just separate the two lines...you might have to work them a bit.
 

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The clip will unsnap about halfway, no need to completely remove. Then just separate the two lines...you might have to work them a bit.
OK, thanks.
 

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Before I comment, an FYI - I've been involved in fuel system design for > 20 years and actually worked with Lotus on their 2.2L turbo and Chevy LT5 programs. A couple of points. 1st, Regulators in recirculating / return systems should ideally be located at the rail. That reduces pressure pulsations induced by the injectors and the amount of time required by the regulator to react. It also helps with hot fuel handling / hot restart because it can more quickly purge the vapor at the top of the rail. 2nd, fuel system design is a lot harder than it looks. If improperly designed, a system can resonate leading to rich or worse, lean cyclinders under certain operating points. Since people are running these pig rich, maybe that doesn't matter (unless the cylinder walls are getting their oil too washed down with fuel).

The fact that the Lotus rail's inlet is on one end is not necessarily bad, and moving it to the middle won't necessarily help anything if it wasn't optimized for the car, injectors, fuel lines, and calibration. I cannot emphasize how much work goes into designing, testing, and calibrting fuel system for cars. It usually takes OEMs 3 or more years with an unbelieveable amount of resources.

Anyway, I'm not saying that any of this bad stuff will necessarily happen with this rail, I would just like to see some system data before buying it. Otherwise, it looks like a nice piece.
 

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Dave; Do you expect to have to alter your ecu tune by swapping the fuel rail?
I believe he will. Dave may use charlies new tuneable solution or swapping back out for the xede to tune it.
 
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