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?

 

[Neal R19]

Look it up on the EPC. Whats the chassis code for an R26? 225 is CM0M or BM0M...

 

[andybond]

CM2H for the r26
CM0M IS 3RD 225
BMOM IS 5DR 225
CM1V IS 3dr 225 WITH CUP PACK
BM1V IS 5dr 225 WITH CUP PACK

 

[Neal R19]

Same 2 options listed for both BM0M and CM2H.

8200683188 or 8200689362

The one from my 225 looks like 8200683188 so I guess the R26 if different must be 8200689362.

Google images of that version tbh look like it too has the same size FPR, hard to tell though.

 

[Mart]

Good info

 

[Ewan]

This is interesting, I should try and source a spare fuel sender from a R26 and check the fpr.

So, the Lexus fpr looks to be the same size as the 225 one?

 

[SP33DY]

Negative Ewan, the R26 uses the smaller FPR. But if you can retro fit a 225 sender unit and simply pop in a 5.5 bar standard size Bosch FPR I'd say it's the way to go.

The option is still a VW and return line.

 

[Ewan]

Ok, will source a 225 sender then. If the fpr from the 250 fits, will source an uprated pump from the French which has a higher flow rate.

What's a VW? Did you mean swirl pot and external pump..

There is a guy up here with a R26R running 400hp+ and it's fitted with a external swirl pot and 044 in the spare wheel well. Much quieter located in there, although still stinks of fuel even with Teflon lines! In tank solution is still the neatest and least intrusive

 

[tutuur]

Googling 225 pump gives exactly the same result as Ewan and i have, they all look alike. Could be the ph1 225 has a different style pump ir the pump you have is no 225 pump....

How did the rods turn out?

You don't need to buy the french pump Ewan, it's nothing more then a DW65c pump, confirmed sizes with my pump and it should be a direct fit

 

[SP33DY]

Rods came out really nice mate, I actually pulled out of the sale of the Meg at the last minute so still have it. I'm probably going to use my spare bits on it.

I've got a bosch 044 pump in the clio with Teflon lines and I can't smell any fuel at all, but 182s don't have a spare wheel well so it's on the boot floor and it's pretty noisy.

The VW 1.8t has the same injector spacing as an f4r/t so with a little bit of tweaking you can have a traditional fpr on the fuel rail set up with a return line back to the sender.

 

[tutuur]

It doesn't mate, it does between 1&2 and 3&4 but the middle is wider. Tried that. Also it fouls on the manifold so if you want a return system on a 225 it's time for a custom job.

Any pics of the rods mate? I think the 250 rods are pretty slim at the top so wouldn't know how they would cope tbh. You'd have to take a fair bit of material away. I'd rather machine the pistons but don't know how that will turn out either....

 

[Neal R19]

Converting the 225 non-return fuel rail to a return system just involves teeing into the feed line just before the rail, fitting a standalone regulator there (this is so you can use a rising rate reg and get a intake vacuum feed to it, yes?) then just run the return from that back to the tank/swirl pot?

 

[tutuur]

That's an option aswell, be sure the regulator regulates pressure after it though, normally they bleed off pressure that stands behind it, you need it to work the other way around

 

[SP33DY]

Arthur are you certain the vag rail doesn't fit? I've seen them used. Wonder if there is some variation between them.....

Back to using an external fpr your basically recreating the standard set up, where the fpr regulates everything upstream of it. Only this way you have boost compensation.

 

[SP33DY]

Looked on the Jenvey website and the f4r injector spacting is 89mm. Looking at alternatives now but I'm swayng towards @Neal R19 suggestion. I just can't see a pump running at 5bar plus lasting long and there was an old post that the wiring had burned out due to high current when using an aftermarket pump.

 

[Neal R19]

That's an option aswell, be sure the regulator regulates pressure after it though, normally they bleed off pressure that stands behind it, you need it to work the other way around

I see what you're getting at there, but you'd need to use a different rail or modify the standard one with an outlet in order to regulate pressure after.

How come there's a difference between bleeding pressure off before the rail or after?

 

[Mart]

I just can't see a pump running at 5bar plus lasting long and there was an old post that the wiring had burned out due to high current when using an aftermarket pump.

Could always wire in a triggered (from the pump +ve feed) relay, taking a direct feed from the battery.

I'm hoping the VAG/Bosch 4bar reg fits in the 225 sender, as if so, that slight increase in rail pressure will be perfect for my fuelling goal. Gonna pull the sender out after Croft TD to see what's what.

 

[tutuur]

You CAN use a normal regulator but it has everything to do with how it operates. The reg will normally hold pressure béfore it and bleed off the excess. So if you want to use something like that you'd have to tee it off the line instead of placing it inline.

This way it will keep the whole fuel line back to the fuel pump ( with 550kpa reg fitted) under a constant pressure of 3,5bar, pressure compensated.

As regards to Steve's notification, i've read the posts about burning out the upc aswell but on the other hand there are numerous of people who had uprated pumps fitted so it might've been a one off? As regards to your notification of the pump having to maintain 550kpa at all time, do realise the only loss will be through the fpr directly back into the fuel tank, when using a return system you would constantly have the excess fuel delivered by the pump flowing through the whole system. As you'd probably know a restriction get's multiplied by the length of the restriction.

In regards to Marts post, the ecu will compensate for the pressure difference so fuelling will remain same as standard, as you've mentioned though the output will increase, i'm at 92% DC now and haven't had it on the dyno but comparing it to my previous tune which made 270bhp at 82% DC i'm guessing i'll be around 290bhp atm

 

[andybond]

i'm at 92% DC now

Isnt that a little high ? The injectors tend to go static around 92% duty.

 

[tutuur]

Who says so?

Yeah it's on the high side but it's only temporarely. It peaks at 92 around 5500 and then settles below 90, mind you, standard 225/230's run 88% out of the box

 

[andybond]

75-80% I heard standard.