Trackspec Clio 197

[Yiannis197]

Blimey here are some worn tyres!!

 

[trackspec197]

Blimey here are some worn tyres!!

They’re ok mate! At least another few days in them! haha

Fitted one of the wheels tonight. Not sure on the colour combination so planning on matt black.




Also made this heat shield this evening.

 

[Sean197]

Good idea with the heat shield, I noticed my brake fluid bottle got a bit hot so I just wrapped it in heat proof tape.

 

[Yiannis197]

Loving the orange on blue, wheels need to be loud but then again I might be biased

 

[peter]

Loving the orange on blue, wheels need to be loud but then again I might be biased

don't listen to mr. red wheels. go mat black.

 

[Pav]

i've done the same with mine..heat proofed it too..
looks good..

 

[trackspec197]

Fitted the new Walbro 255 pump today and quick oil change.

 

[Sean197]

How was it to fit Matt, did it fit in the standard pump carrier and I take it the fuel gauge etc still works ok?

 

[trackspec197]

How was it to fit Matt, did it fit in the standard pump carrier and I take it the fuel gauge etc still works ok?

Yes it’s a straight fit mate just joining the wiring to the genuine connector but a simple job. Gauge is working fine.

 

[Sean197]

Yes it’s a straight fit mate just joining the wiring to the genuine connector but a simple job. Gauge is working fine.

Good to know, ta.
What will you do about the return from the meg 250 fuel rail?

 

[trackspec197]

The standard 250 rail doesn’t have a return. My plan is to modify it by welding on two fittings for the feed and a return then run a regulator after the rail then back to the tank.

I’ll remove the standard 250 rail feed and regulator.

 

[Big Ben]

Matt can you explain the benefits of a feed and return over just using the uprated pump? I’m following this as close as I can but some things are over my head!

 

[Big Ben]

Looks as if having a return there’s no delay in fuel arriving at the rail as the pump is always at 100%.
Bit of googling

 

[Pav]

gotta love mr google

 

[rSilva]

On a turbo car you use a return so that you can have a rising rate regulator and a constant fuel pressure at the tip. If you don't raise the fuel pressure along with boost you end up loosing effective pressure on the injector tip. Less pressure means less flow the injector can make.

3bar of fuel is only 3bar at ambient pressure. If you're feeding 1bar of boost into the engine you only have 2bar of fuel pressure difference. Raise the fuel to 4, subtract 1 for the boost and you have 3bar for the injector to work with.

 

[Sean197]

On a turbo car you use a return so that you can have a rising rate regulator and a constant fuel pressure at the tip. If you don't raise the fuel pressure along with boost you end up loosing effective pressure on the injector tip. Less pressure means less flow the injector can make.

3bar of fuel is only 3bar at ambient pressure. If you're feeding 1bar of boost into the engine you only have 2bar of fuel pressure difference. Raise the fuel to 4, subtract 1 for the boost and you have 3bar for the injector to work with.

My understanding is that a rising rate regulator is pretty old school, and a modern engine's ecu can trim the fuel pressure accordingly when boost is applied. Hence the megane 250 having (from memory) a 5bar regulator in the tank coupled with a 3bar (possibly 3.5?) regulator at the fuel rail. Therefore a walbro 255 pump with a regulator should in theory be fine, as demonstrated by RS Tuning's 450-odd bhp r26r.
Happy for someone with a more in-depth knowledge than me to explain otherwise!

 

[rSilva]

If it has an in-tank regulator of 5 and and a 3 on rail means that the rail one bleeds the difference to keep 3 bar on injector tip. That setup will not be able to keep the 3bar of injector tip fuel pressure after 2bar of boost (if the pump and injectors are able to flow enough for the engine to make that boost)

The NA engine doesn't have a return because it sees no boost and the ECU knows that the fuel pressure is what the regulator in the tank sends plus the intake vacuum (on parth throtle)

 

[Sean197]

If it has an in-tank regulator of 5 and and a 3 on rail means that the rail one bleeds the difference to keep 3 bar on injector tip. That setup will not be able to keep the 3bar of injector tip fuel pressure after 2bar of boost (if the pump and injectors are able to flow enough for the engine to make that boost)

The NA engine doesn't have a return because it sees no boost and the ECU knows that the fuel pressure is what the regulator in the tank sends plus the intake vacuum (on parth throtle)

Thanks. Yeah I understand the general workings, and I've just read the 250 fpr gives up to 5 bar at the rail which will be plenty. Also, Matt's (@trackspec197) engine has 630cc injectors (I know as it's my old engine) which compensate for the usage of the clio fuel pump by opening for longer at a lower fuel pressure thus giving the same results as a higher pressure fpr.
For general info, a 'stage 2' RS Tuning map gives 1.4bar I believe on a standard 225 turbo (Matt can your turbo gauge show boost?) So 2 bar of boost with a 250 turbo would give near high-300 bhp so shouldn't really be an issue on most builds.

 

[Sean197]

And for further reference, a mk3 megane tce fuel rail apparently has the same part number as a 250 rail. Bloody renault!

 

[trackspec197]

Thanks. Yeah I understand the general workings, and I've just read the 250 fpr gives up to 5 bar at the rail which will be plenty. Also, Matt's (@trackspec197) engine has 630cc injectors (I know as it's my old engine) which compensate for the usage of the clio fuel pump by opening for longer at a lower fuel pressure thus giving the same results as a higher pressure fpr.
For general info, a 'stage 2' RS Tuning map gives 1.4bar I believe on a standard 225 turbo (Matt can your turbo gauge show boost?) So 2 bar of boost with a 250 turbo would give near high-300 bhp so shouldn't really be an issue on most builds.

Yes mate I can get boost through it too.

I’ll be a running a adjustable rising rate regulator after the rail and setting it to 3.5bar. The plan is to bypass the regulator in the sender and run the fuel pump direct to the sender outlet with the return flowing back to the sender and to the pump again.