Megane RS250 engine into R26 - using mk3 fuel pump

[Ewan]

I am swapping the engine in my R26 with a RS250 unit retaining the R26 ECU and loom. Should clarify at this point that 'I' means 'I am paying Rentec in Edinburgh'

Ok, so we are keeping the R26 ECU and loom and swapping in the RS250 engine with turbo and the mk3 inlet manifold, fuel rail and injectors.

I know that we should be able to run the RS250 engine with the existing mk2 fuel pump, although it won't offer the rising rate fuel pressure. The question is can we fit the mk3 fuel pump to my car and take advantage of the rising rate rail with the mk2 ECU and loom without a massive headache?

 

[andybond]

I'm not backing down, I still say they'll do 400 or there-abouts with a raised rail pressure. However, the 14/15t units won't flow anywhere near that power, so it matters ye not anyway.

Using actual real science ( or more accurately a online calculator ! ) It tells me otherwise. So Ill not back down either. Prove me wrong Mart. Ill start looking for another engine for you when everything goes Pete Tong

You can run a injector upto about 92% cycle before it becomes static pulse. You would be mad doing that.

I based my calulations on using static 3.5 bar.

 

[tutuur]

Megane injectors are 390cc, at 285bhp, 12-12,5afr and 1bar of boost they're at 90% on mycar.

Simply saying add the 1 bar to 3,5 and multiply won't give you the new output, it's not linear. According to my calculations, IF you maintain correct base pressure you'll still be limited to around 320bhp....

 

[Mart]

I thought 225 injectors were 480cc?

In that case, I stand corrected.

 

[Mart]

I based my calulations on using static 3.5 bar.

Which wouldn't be the case if running a rising rate fpr, a la mk3 Megs - Then it would be 5bar, assuming 1.5 bar boost (is that what Paul maps them to?).

I make that 365hp ish @ your 92% duty limit, but bump up the base rail pressure by 0.5bar, and, everything else being equal, I make that 380hp.

Again, assuming 225 injectors are 480cc, which I thought they were...

 

[andybond]

Which wouldn't be the case if running a rising rate fpr, a la mk3 Megs - Then it would be 5bar, assuming 1.5 bar boost (is that what Paul maps them to?).

I make that 365hp ish @ your 92% duty limit, but bump up the base rail pressure by 0.5bar, and, everything else being equal, I make that 380hp.

Again, assuming 225 injectors are 480cc, which I thought they were...

Yeah , but 380 isnt 400. And you have now found another magic .5 bar of pressure on the rail whilst running an injector at its balls out max limit with is flowing too much anyway ( as said earlier )

I could make a standard meg do 400bhp. Once. For one 1/4 of a mile , but the point still stands. The Meg r26 injector will not , cannot flow enough for 400. Which is exactly why the 630 Deka Short is used to make good , safe , reliable power.

 

[Mart]

I originally said 'or there-abouts'.

Increasing rail pressure is pretty much what I've been on about since my first post in this thread, so I'm not magically finding anything all of a sudden?

 

[tutuur]

Bumping rail pressure would be way more involving than fitting 630cc's, that why people fit them.
The correct way in my books would be to alter the fuel system to M3RS specs but that would mean a custom fuel rail, fiddling with the OE pressure reg etc., much easier to fit 630cc's in about 10mins and be done with it....

 

[tutuur]

Correction, 390cc at 3 bar, so about 420 at 3,5 bar.... Atleast, that's what i've found so far, never had a set tested.....

M3RS injectors are 496cc at 3 bar according to specs online, way more interesting for tuning purposes!

 

[andybond]

Correction, 390cc at 3 bar, so about 420 at 3,5 bar.... Atleast, that's what i've found so far, never had a set tested.....

That looks spot on from what I have seen

M3RS injectors are 496cc at 3 bar according to specs online, way more interesting for tuning purposes!

Back down the custom rail / custom other bits again :/

 

[tutuur]

No, fit a M3RS engine instead, lol!

 

[SP33DY]

@tutuur @Ewan Gents do either of you have any photos of the actual FPR on the 250 fuel rail?

 

[Ewan]

No, but I can get one at the weekend.

 

[tutuur]

Nothing usefull of information on it mate, only a renault number.... Need to set up a fuel pressure rig i reckon

 

[SP33DY]

It's the physical look Im after. Is it the same as a standard reg?

 

[tutuur]

could be smaller from the top of my head. Won't be near it for a while though so you would have to wait for Ewan to check i think

 

[tutuur]

Just had a look, it does look the same, there's only minor differences but fysically it will fit. There's only one problem though, it seems flow through the fpr is opposite vs the intank reg.

Imaginable though as normally the fpr's regilate by bleeding off pressure and this one does it by feeding it. So simply finding a different reg won't be easy!

Only thing i want to find out is what pressure it will regulate. I'm guessing 3,5bar

 

[SP33DY]

Yeah that's what I expected. It works more like an air pressure regulator so it's fed by a high pressure source and once it hits is preset pressure it actually blocks any incoming fuel/pressure. If it was plumbed in like a normal fpr it would just run at tank fpr pressure.

 

[SP33DY]

Well one of the lads has offered to buy my R26 off me. So it's going when I get home. I'll still check the pressure regulator on that lexus sender and also pump compatibility. But that will be as far as I go.

I now need to buy a sensible ish car and resist the urge to buy a Clio 200. However with a full 250 engine (with forged rods), an ND0 box with an R26 diff, hybrid turbo, decat downpipe, 90mm airtec cooler, spare driveshafts, a SMF with R26R cover and 6 puk friction plate. I feel I'm only a set of injectors and ecu away from a straight forward conversion. I've even got a brand new set of 250 calipers for a big brake conversion.......

 

[andybond]

Justification reasons .

Buy it. Now.

 

[tutuur]

Do it mate!!!!!

You won't need the paddle though, r26r(diesel) clutch will hold 360lb/ft all day long according to Paul@RST