Fuel systems

[litchy]

My current set-up is standard Clio sender and pump with the 250 meg engine and standard 3.5 bar fuel reg on the rail. The pump is 3 bar.

Originally the car made 286bhp on that set-up, then Paul at RST had to fit bigger injectors (630) in order to draw enough fuel to make another 308 bhp. Really need to increase the fuel pressure as it should be capable of another 20+ if I get the fueling right.

Thinking fitting return system but that feels like overkill for 20 bhp. I've tried fitting a meg 225 sender with up-rated pump as it would have been good for 4 bar static but wont fit.....

Any ideas????

 

[marinemackay2003]

walbro 225 pump ?

you must be nearing the limit of standard pump at that sort of power

FUEL SYSTEM
I retro fitted a complete PH1 fuel line, sender unit and fuel rail set up. I used a 255LPH fuel pump and a 3 bar regulator along with a set of siemens 630cc injectors. This allowed me to run 374bhp at approx 75% duty cycle.

from steve (T Trophy )'s thread on building a 300 plus engine

 

[marinemackay2003]

also have a read in here

http://www.cliosport.net/forum/showthread.php?510816-clio-172-fuel-pressure

I have a 182 turbo that I retro fitted a PH1 fuel system to.

I did have a diagram somewhere on how it all works but your thinking along the right lines, basically by having the FPR connected to a port on the manifold your equalising the pressure inside the FPR to the same pressure as whats in the intake manifold allowing the preset spring tension to control fuel pressure regardless of boost conditions.

The theory is that when you have 1 bar of positive boost in the intake system that when the injectors are firing the fuel system is also seeing this boost, now if you have a 3 bar FPR it means you will only need 2 bar of fuel pressure required to open the 3 bar FPR, obviously if you put 1.5 bar of boost through it the fuel pressure will drop to 1.5 bar as the FPR will still be seeing 3 bar of pressure despite it being a combination of both air pressure and fuel pressure.

However by pressurisng the FPR to the same pressure as whats in the intake manifold no matter what boost pressure you run, the FPR won't open untill it is 3 bar above whatever is in the intake manifold.

The theory seems sound to me and I've checked numerous standard turbo cars and they all run a FPR with a pressure reference port even the GF's little smart roadster has one as well as all 1.8t VAG engines. The only concern is when running really high boost for example if you have a 2 bar turbo system and a 3 bar regulator, potentially in the fuel system you could have 5 bar of pressure?

Hope that makes sense mate, I'll dig around to see if I can find the article, also theres a few others on here who are quite switched on about turbos systems who might be able to cofirm/clarify the above.

Steve


again from T Trophy

maybe worth a look ect

 

[litchy]

Thanks Steve,
My car is a hybrid of clio 197 fuel system, meg 225 ecu and meg 250 engine. All originally are non return systems.
The clio is obviously NA with 3 bar reg that sits in the swirl pot of the sender unit.
The Meg 225 fuel system reg sits on top of the sender and is 3.5 bar but has no fuel reg on the fuel rail.
The Meg 250 fuel system reg also sits on top of the sender but is 5 bar and has a 3.5 fuel reg on the fuel rail.

Interestingly, the Meg 225 set up is good for 330+ bhp standard. Unfortunately, the 225 sender wont fit so I'm going to have to try and modify the 197 sender. Another option is to use 172 sender as they do an uprated pump and its easy to change the fuel reg.

 

[Gray]

Litchy,

Totally forgot to get in touch with you regarding the Megane fuel pump you have.

I need to ask Paul at RStuning if it would be suitable for my new forged engine. If so I will have it from you.

 

[NorthloopCup]

Do you have any pictures of the pressure regulator? You might be able to get away with giving it a little crush in a vice to increase the fuel pressure. Sounds crude - which it is, but they used to do it all the time on the vauxhall let motor running eds management.

 

[litchy]

Might be easier to just go down the route of a return system. So thats modified fuel rail, adjustable FPR, swirl pot, bosch 044 pump, fuel lines and fittings?