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#1 Statler

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Posted 26 October 2014 - 05:40 PM

The stock VN 304 fuel rails that i have are going to cause me clearance issues.

The p/s outlet points the hose straight back into the firewall/heater box. The d/s outlet shoots the hose into the brake booster. 

 

The 'push on' EFI adaptors will make this even worse, particularly on the p/s. 

 

The easiest solution is to buy a pair of aftermarket fuel rails with -8 fittings. Roughly $150 - 200.

 

Even easier would be to weld on some -8 fittings to the stock rails, but here is the problem ......

 

The d/s rail has a vacuume solenoid fitted. What will be the result if i delete that? 

 

Aftermarket rails don't have it. 

 



#2 EunUCh

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Posted 26 October 2014 - 06:00 PM

The vac.solenoid is a vac. operated fuel pressure reg. that adjusts fuel pressure according to "MAP" to try and compensate pressure drops due to "high" MAP/low "MAP" so that on a high manifold vac.  the fuel don't get "pulled" out of injectors on hi vac...i think..

"Low" mani.vac. would mean the opposite...needs more pressure on injector to push fuel in.??? dunno, been a long day :)

 



#3 UCgazman

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Posted 26 October 2014 - 06:31 PM

I could be wrong but aren't the VT fuel rails different and give a little more room at the back? It was a while ago when I heard this but was considering getting some because mine is tight for space there too.



#4 EunUCh

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Posted 26 October 2014 - 07:05 PM

Don't delete that little bit with the vac. take-off line that lives on the end of fuel rail ,it goes goes to manifold vac/fuel rail...move it out of the way by plugging the original hole and re-drill another point preferably at end of rail at the right angle...(not right angle) to clear.

It needs mani.vac. to talk to fuel pressure...at idle..hi vac. when foot is where it needs to be...low vac.or WOT.

The electronics will hopefully take care of the rest.

 

 



#5 mick_in_oz

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Posted 26 October 2014 - 08:41 PM

I'm not sure what other items might get in the way, but how about swapping the rails side for side, put the reg and inlet out the front? Might have to drill new mounting holes in the rail flanges. Will the cross over then foul on the dizzy? just a thought...

 

As above, you need to keep, or have a manifold referenced regulator.



#6 76lxhatch

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Posted 27 October 2014 - 06:57 AM

I just tweaked the hose tail on each side to fit, the driver side is quite short so you have to be careful with it and the the passenger side ends up hidden behind the manifold but it works for a low-budget solution.

The fuel pressure regulator is the one and only, obviously you need that in some form. The later model (not sure when they started, have seen them in a VR but couldn't guarantee its original) rails are a bit smaller as also mentioned above which would help.

#7 Statler

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Posted 27 October 2014 - 12:14 PM

The MAF runs off a port in the intake manifold. 

 

I have a rising rate fuel pressure regulator ( part of the blower kit) which also runs off another port in the intake manifold. Both of these ports are seperate from the usual vac tree that the booster runs off. 

 

So if i have vacuume for the reg, & vacuume for the MAF, do i still need the stock fuel rail vac unit?



#8 76lxhatch

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Posted 27 October 2014 - 03:30 PM

Vacuum can come from anywhere but the fuel pressure regulator needs to be plumbed into the fuel line somewhere in the return in order for it to work. I wouldn't recommend an actual rising rate regulator as its a band-aid fix for when you can't set the ECU tune properly, just makes it more difficult when you can (although sometimes the terminology is mixed up and it may not actually be rising rate).

#9 Statler

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Posted 27 October 2014 - 03:42 PM

The rising rate reg is part of the Terra Charger kit.

 

I also have a Holley pump here, i've decided to not use it, but instead stick with the kit unit. 

 

Yes, the fuel reg needs in/return & vac.



#10 wot179

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Posted 27 October 2014 - 03:45 PM

Give yella terra call, col.

#11 axistr

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Posted 27 October 2014 - 04:23 PM

I didn't have too many problems fitting the fuel rails to the SLR, I cut down the height of the heater box then heated & bent the inlet pipe to 90 degrees. The regulator wasn't an issue, all fitted up no mods needed.

 

Correct me if I am wrong but to my knowledge the vacuum hose on the regulator is only there for start up, when there is no vacuum the pressure is regulated higher for slight more enrichment. Giving it wide open throttle when running doesn't seam to give it a higher pressure. The slight vacuum increase drops the rail pressure by around 10 P.S.I 



#12 EunUCh

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Posted 27 October 2014 - 06:17 PM

I was just wondering if it really matters where the reg. lives on the fuel rail ?,

After all ,the line pressure will be equal in rail so you could probably put it anywhere near the end ,now that a blower comes into the 

equation things  change with the extra air being pumped in you will probably need to use the one supplied.

 

If the slight vac. causes a 10psi drop at idle,should line pressure increase a bit as vac. drops off as if it were going close to start conditions ?..not sure? but i would think that if the vac. was going away that it would ?..interisting stuff nonetheless.

 

I think on blown engines they also have a sensor on the pressure side (boost side ) of blower to tell the box of tricks what to do with injector pulse when it all starts happening ? 


Edited by EunUCh, 27 October 2014 - 06:18 PM.


#13 Statler

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Posted 27 October 2014 - 06:55 PM

What is the fuel rail mounted vac unit going to do that the fuel reg isn't?



#14 mick_in_oz

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Posted 27 October 2014 - 07:14 PM

The idea of the manifold referenced reg is to maintain a constant pressure across the injector, so that reqardless of the manifold vacume/pressure conditions, the injector experiences the same pressure differential, this is to guarantee the injector will perform as expected with respect to fuel delivery volume and spray pattern.

 

A very common pressure is 3 bar or 43.5PSI, some injectors are forgiving at different pressures and other less so.

 

If I saw 10psi on a fuel rail with the engine running I'd be kinda surprised. I have head reports of faulty regs offering incorrect pressure being responsible for poor power or poor economy.



#15 76lxhatch

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Posted 27 October 2014 - 09:34 PM

The idea of the manifold referenced reg is to maintain a constant pressure across the injector, so that reqardless of the manifold vacume/pressure conditions, the injector experiences the same pressure

Exactly - applying pressure to the manifold end requires an increase in the pressure at the rail end to keep it constant. Rising rate regulators take this one step further and actually increase the pressure instead of keeping it steady, as a band-aid method of providing more fuel under load. Its a lot simpler if its maintained at a fixed pressure because then you have a consistent result for tuning and the injector runs at optimal pressure.

The regulator vacuum reference is required at all times, otherwise the pressure across the injector would change with manifold vacuum.

I was just wondering if it really matters where the reg. lives on the fuel rail ?

It must be placed at the return after all the injectors, any injectors positioned after the regulator wouldn't see regulator pressure as they would be open to the tank return line.

#16 EunUCh

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Posted 28 October 2014 - 04:32 PM

??? So to keep a constant pressure at the injectors does this mean that say at idle with a mani.vac. of 17hg (-6 psi) that with a positive

injector pressure that at that mani.vac.  it would help pull fuel out of the injector at hi vac. resulting in an over rich mixture due to minimal injector pulse on time ?

 

I see, as long as it is after the last injector,but it wouldn't matter if it stuck out one side to avoid clearance issues?



#17 Statler

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Posted 29 October 2014 - 12:35 PM

Here's the layout.

 

9e3fdc12-6963-423a-805d-fba266eedba3_zps

 

Fuel is being pumped up the line by a Bosche 44. It enters into the top of the intake pipe. (braided hose existing)

 

From there it exits the other side of the intake pipe after feeding the extra micro-controlled injectors, & into the fuel rail.

 

Flows thru the rail, exits on the drivers side, (where the rail vac unit is)  then into the pulse dampner.

 

Dampner to the kit supplied rising rate regulator, then returns to tank ( or in this case, back to surge tank then onto fuel tank).

 

NOTE: Dampener & fuel regulator are not yet mounted in position. I just laid them on top for clarity.


Edited by Statler, 29 October 2014 - 12:37 PM.


#18 76lxhatch

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Posted 29 October 2014 - 01:45 PM

The damper doesn't necessarily need to be there, later models had it at the rail but earlier ones (possibly only those with external pump?) had it at the pump. If your pump doesn't introduce significant pulsing into the system you could easily get away with not having one at all.

As EunUCh suggested the regulator can go anywhere at the return end, maybe weld your fittings on and run a hard line to it mounted in some convenient spot (attached to the engine, don't run flexible line to the regulator).

What is their reasoning for the extra injectors, seems like another band-aid fix? My preference would be to run the standard rails with eight decent sized injectors, a standard regulator and a proper tune.

??? So to keep a constant pressure at the injectors does this mean that say at idle with a mani.vac. of 17hg (-6 psi) that with a positive
injector pressure that at that mani.vac.  it would help pull fuel out of the injector at hi vac. resulting in an over rich mixture due to minimal injector pulse on time ?

I think you are understanding correctly, if I understand you. The regulator keeps the pressure difference between the two ends of the injector constant, even though manifold pressure varies.

This where the whole rising rate regulator confuses things, because it adds yet another variable by altering the pressure instead of keeping it constant.

I see, as long as it is after the last injector,but it wouldn't matter if it stuck out one side to avoid clearance issues?

Correct. Only other consideration is allowing enough fuel flow, note the regulator needs to flow highest at idle when the engine is consuming the least fuel.

#19 Statler

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Posted 29 October 2014 - 02:51 PM

The damper doesn't necessarily need to be there, later models had it at the rail but earlier ones (possibly only those with external pump?) had it at the pump. If your pump doesn't introduce significant pulsing into the system you could easily get away with not having one at all.

I disagree with this. There is a note in the assembly instructions to include the dampener between the fuel rail exit & the reg.

 

My understanding is it is for dampening the injector pulse, not the fuel pump pulse. If it wasn't required, why would Yella Terra insist on using it?

 

As EunUCh suggested the regulator can go anywhere at the return end, maybe weld your fittings on and run a hard line to it mounted in some convenient spot (attached to the engine, don't run flexible line to the regulator).

Why not use flexable lines to the reg? 

 

What is their reasoning for the extra injectors, seems like another band-aid fix? My preference would be to run the standard rails with eight decent sized injectors, a standard regulator and a proper tune.

The extra injectors are to supply additional fuel as required by the demand. It's isn't a band-aide fix, it's a proven Yella Terra kit. 



#20 EunUCh

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Posted 29 October 2014 - 05:52 PM

Some (most) flexible lines expand under pressure,although a good braid would probably be ok...was a big thing about braided front lines on Motor cycles

years ago,the "experts" deemed the braid dangerous when in fact the "stiffer" line was better...same principle.

 

Just as a matter of interist..how many Liters Per Revolution (blower Revs)  does  the blower pump ? 



#21 76lxhatch

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Posted 29 October 2014 - 07:03 PM

I disagree with this. There is a note in the assembly instructions to include the dampener between the fuel rail exit & the reg.
 
My understanding is it is for dampening the injector pulse, not the fuel pump pulse. If it wasn't required, why would Yella Terra insist on using it?

It was just a suggestion if you're stuck for space, some pumps are worse than others. Any pulsing has the potential to have an affect on the pressure at a given instant which is why they're used, but its not always a significant issue. I agree that the injectors could contribute but I'm not sure the damper could work fast enough to keep up with them?

 

 

Why not use flexable lines to the reg?

Some (most) flexible lines expand under pressure

This, you will end up with more pulsing and unreliable pressure regulation.

 

The extra injectors are to supply additional fuel as required by the demand. It's isn't a band-aide fix, it's a proven Yella Terra kit.

Whatever you like, it does save you from having to buy as many new injectors if the existing ones are not adequate. I was just saying that my preference would be to run decent sized injectors at the ports only, and give it a proper tune. I did ask what the reasoning was, in terms of just supplying fuel its a band-aid but maybe there's more to it - perhaps the blower works better/lasts longer wet?






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