Uprated fuel system?

I apologise if these are simple questions, trying to educate myself on a few things in advance of an RS250 swap into my R26. This thread is great info but there are some basics I'm not following.

I'm replacing my fuel pump with a DW65C. This is as much for the fact it's done 112k miles than anything else.

Where I'm getting a bit confused is around the rising rate set up of the 250 FPR.

From what I understand, the R26 set up is a FPR in the tank and none on the fuel rail. This means the pressure is set to 3.5bar, is that right?

What window of pressure do the injectors require to operate efficiently? 1.5 bar boost means 2 bar fuel pressure. I don't see myself pushing boost too high!

Can i change my fuel pump and leave the normal 3.5bar prv in the tank? Why does this need to be upgraded to the 5.5bar one?

As I'm using the 250 engine, I want to use the better fuel rail set up naturally. Let's work on the basis I set it up as advised, DW65C fuel pump and 5.5bar FPR in the tank modified to fit. The next bit I'm struggling with is the FPR on the 250 rail and the rising rate.

Firstly, when it says rising rate is is set up to maintain a set fuel pressure and what is it? It takes the boost pressure feed from the manifold so if I assume it's Trying maintain 2 bar real/differential fuel pressure, does that mean at zero boost it gives 2bar and at 1.5bar it gives 3.5 bar pressure?

Is this for economy or better fuel control up high?

The advice is to leave the boost reference off the reg until mapped, that means it runs steady 3.5bar pressure and that is the advice as the R26 ecu is not set up to adjust for rising fuel pressure?

So many questions so I really appreciate anyone that is willing to give the time to educate me here! I've tried YouTube but going dowm wrong rabbit holes

 

Double post

 

@Chawkie
I will try and run through this for you, firstly the DW65c is easier to fit in the mk2 tank unit, you need to replace the FPR from the 3.5bar one to a 5.or 5.5 bar one, this needs a bit of modifying, the pin bit is too big t fit in the housing, it needs turning down from i think 7mm to around 5.7mm, you need to check this when you remove the one that's in there now.

The optimum pressure for the the injectors to run is 3 bar, that is why the mk3 has the rising rate setup.
You can run the 3.5bar fpr in the tank if you are not wanting too much power, as the boost climbs the fuel pressure will drop in the cylinder, then the injectors need to run for longer, are you using 630 injectors ????.
The fpr valve on the inlet manifold on the mk3 is set to 3 bar, so it can run 2.5bar of boost in theory, but the injector open times can be extended in the mapping process.

This 250 engine, does it have the inlet manifold with it ???
It would be easier in some respects, you will need the fuel rail from a mk3 to try and stop the ring land frailer problem, but then you need to make an adapter for the R26 throttle body.

All this work is for fuel control, it does give better fuel economy once mapped.

You need to make a fitting on the intake manifold for the rising rate pipe, this needs to be blanked off and the pipe on the fpr valve needs the small green "O" ring removed till your at the mappers.

Keep the questions coming if your not sure on anything

 

You're the source of alot of my knowledge lately so thank you!

I have a full 250 engine, including rail.

So if I understand correctly. With the fuel rail FPR disconnected from the intake manifold, it makes a solid 3bar. So if the car is producing 1bar of boost that is 2bar fuel pressure. And this is similar to how the current R26 engine works.

But when being mapped, and we connect up the FPR to the intake manifold, the rail FPR will increase pressure from its base setting based on the boost reference it receives so could take from 3bar base and increase by 1.5 bar to 4.5bar for example to compensate for 1.5bar of boost pressure. The maximum pressure it can run to is 5.5 bar as dictated by the FPR on the pump?

Just to clarify on the rail FPR. This is to be left open to atmosphere when disconnected, not capped? Obviously, the intake manifold cannot have a leak so does need to be blocked until mapped.

What is the purpose of the green o-ring?

 

That is right, leave the pipe off, but you need to block it at the manifold end.
Will run as a standard R26 would with that pipe off the fpr.
But you need to take out the small green "O" ring, but keep it safe as you will need it when you reconnect the fpr pipe.

When you are at the mappers, reconnect the pipe to the fpr, they will then reduce the injector time so it doesn't run to rich.

The system will run 5bar to the regulator, that keeps the fuel in the rail at 3 bar and as the boost rises it compensates by letting a higher pressure into the rail.

Yes leave the fpr valve pipe open and block the one to the manifold.

The "O" ring is to let the fpr do it job, when the inlet pipe is connected.

 

Excellent info and support Ian.

Now to find a mapper in Ireland that understands these as good as the UK guys. We also struggle with fuel only being 95octane!

 

Bit of a mine field finding someone that can map the car properly, i drive 5 hrs each way to efi as i have confidence in his work and he's a nice guy.
I wouldn't worry about the fuel octane, they can map it to the fuel you use, okay you might loose a bit of available power but it won't be a lot, i run mine on either 95 or 98 so if that's all that's available it isn't going to do any harm.

 

personally I'd fill tank with whatever the fuel I always use, book slot with EFI and jump on Dublin ferry for day out in sunny Runcorn just for future piece-of-mind but that's just me

 

there's some tricky bits in the reno factory map that need turning off and for sure not all mappers know this

 

Chris from EFI was actually here in Ireland to map a couple of cars last year for a weekend. Might try and organise it again maybe!!

 

Another thing to add to the list if things to do, replace both MAP sensors with the 250 ones, the standard 225/R26 are only set for 1.5bar boost, the 250 ones are set for 2.4bar i think.

Don't buy them from Renault they are a silly price

 

Does the 250 throttle body not work with the 225 ECU?

 

No
Been there and done that, you can get it to work, but then sometimes it stops working.
Needs to be reset by turning the ignition off and on again, not good when your on the motorway in Belgium

 

Anything I've read from UK forums all have this issue but I also messaged Tutuur off here and he has 5 customer cars in NL running the 250 TB!

Mad really the difference on this but I'm going to run the 225 TB to make sure it works

 

He was the one that gave me the wiring diagrams to change the wiring, i had it cut out on a trackday may times as well, make an adapter save yourself the frustration

 

I damaged the throttle body in transit, was thinking of replacing it with a 250 inc the intake manifold but I'll pass on that

 

Can't you find a second hand one
Might be worth speaking with Arthur (tuttur) and see what he has changed in the setup

 

I'll probably go down the second hand route and modify the manifold to take 250 fuel rail, sounds a lot easier!

 

think it'll be the better option to be honest.

 

You will need to swap over the wiring loom as well as all of the sensors.

 

Im currently looking at the fuel setup options for a 250 setup on a project im building and considering fitting 5 bar reg to tank and uprated pump to get my project up and running, then will fit a proper fuel system later on.

I have a lexus reg here, not tried to fit it to r26 pump yet though.

Is the stock pump wiring and upc ok with an uprated pump pulling more power than stock?

 

The standard regulator in the fuel tank is 5.5 bar, so no need to change it, its only the Mk2 that needs a higher regulator if your uprating the fuel system.

You don't need to go any further on the fuel system, the new pump and the rest of it as is, except for the 630 injectors should see 450hp, then its bigger injectors, not worth it for me, i'm sure 400-450 is more than enough.

I had this same pump in my 225 for over a year and never had a problem with the wiring and those wires were thinner.

 

Mine is all based on r26 fuel system so originally 3.5bar reg iirc? so will need to change it. Currently has a walbro 255 fitted by previous owner. Which reg did you use in your 225 with uprated pump? Ill be using 630cc injectors too.

 

I fitted a DW65c into the housing of the 225/R26 housing, its an easier fit than the mk3 one.
Not had any experience with the Walbro, but the DW65c is good for over 240ltrs an hour at 60psi so i think that works out at over 450 HP.

I fitted a 5bar regulator, but you have to get it machined down a bit, down from about 7mm to 5.7mm i think

 

Will have a look at the lexus reg and see how it fits. With it being a 61 reg ren might see if the 250 sender and pump fits. Its a van and i need to clear a load of parts out the back to get to the sender, next job

 

Hi mate, just wondering if you knew a way to run pure pump pressure instead of having a regulator in the tank, I will have a turbosmart fpr800 up at the rail

 

Sorry Aiden
But i have only done the in tank FPR valve modification and used the Mk3 fuel rail.

Maybe you could just block the hole in the FPR valve you have in there now.

 

Ok cheers mate, I’ve been told to take the reg out and drill the hole behind it to about twice as big, I just can’t understand in my head how that would work . I don’t have a spare sender unit to hand.

 

I have the one that i am going to fit once i have run the engine in, i will have a good look at it tomorrow, but i am sure if you block the hole in the regulator its going to put full pump pressure into the fuel line.

 

That’s brilliant mate if you could have a look where the reg sits and remove and take a pic for me it’d be much appreciated as I don’t know what behind the reg looks like

 

Hi mate sorry did you manage to have a look?

 

Yes i have, the pump feeds into a chamber in the middle, that chamber holds the FPR valve and has the outlet pipe also connected to the lid.

As i thought, if you block the FPR valve hole and refit, that will give you full pump pressure the the fuel line.

 

That’s awesome mate, been a big help I appreciate it

 

Ayup mate started getting my sender together today and I’m confused as to what to do with the reg, I’ve welded the small hole on the actual reg to block it. Will that work?

 

Why ???
I left mine open and it works fine

 

To get full pump pressure? I need to bypass the i tank reg? Got a reg up front

 

Have you got the uprated 5bar reg ???
If not, then yes block the feed hole, the one in the bottom where the small "O" ring is

 

Thread resurrection

Currently having lots of new parts fitted on my car. It is running Injectors already, has been mapped by Chris in stanard form and made 265bhp. One of the parts going on is a 250 Turbo (thanks to @Agreen ).

Little bit paranoid about melting pistons etc so was looking at Fuel Rails. I dont really want the car to be over 300bhp, dont want to lose driveability. Would be happy with 285/295 as stock internals at the moment to keep stressses down.

I had seen the MK3 fuel rail mentioned as a fix with the fueling being centre instead of one end on the MK2. Actually bought a Cooksport Rail but think its for more extreme builds than mine.

Is this the 250 rail or a DCi one https://eurofrance24.com/catalog/pr...ane-iii-20-16v-175207852r/?PageSpeed=noscript

Is the 250 fuel rail overkill for a sub 300 engine?

Thanks

 

Your always going to be torque limited to 300lb on the r26 standard engine. And your not likely to make much more and possibly not even 300bhp. Drivability won’t be worse, you should have a slightly broader powerband with the 250 turbo. No need to upgrade fuel rail.

 

Yep, not looking for big power, I want useable power that isn't killing the engine.

Main use is aiming at track use, no benefits from the 250 fuel rail with that in mind?