rising rate pressure reg + low boost

[vnss_1]

hey, heard of people doin turbo conversions using low boost. and using a rising rate pressure reg to pump more fuel instead of a aftermarket comp. any experience on this. mates doin low boost turbo coversion on the cheap.
dont wana hear the crap like dont bother just get a remap etc.
just want experince on the rising rate fuel regs. thanks

[Bz Kn33z]

As far as i know, with low boost like mine aswell, you could get bigging injectors leave the same fuel reg and get it tuned, thats what i am doing i got bluetops on my VN, well i will have when i bolt the charger on and get the tune done.

[DannyboyDS]

hey, heard of people doin turbo conversions using low boost. and using a rising rate pressure reg to pump more fuel instead of a aftermarket comp. any experience on this. mates doin low boost turbo coversion on the cheap.
dont wana hear the crap like dont bother just get a remap etc.
just want experince on the rising rate fuel regs. thanks

It might work, but I wouldn't falt foot it.

what engine are you running? what size injectors? have you talked to greenfoam yet, he does boost chips and they don't cost the world, they can even work out cheaper then a fuel reg sometimes.

You will still need a bigger pump too.

[VT-565]

hey, heard of people doin turbo conversions using low boost. and using a rising rate pressure reg to pump more fuel instead of a aftermarket comp. any experience on this. mates doin low boost turbo coversion on the cheap.
dont wana hear the crap like dont bother just get a remap etc.
just want experince on the rising rate fuel regs. thanks

Just by the look of things, you need to do a bit more homework on what everything does before you start quoting parts etc.

a rising rate regulator is exactly that, uses either vacuum or boost pressure as a pilot signal to cause more/less restriction and increase/decrease the fuel pressure in the rail.
Think of it like your thumb over the end of the garden hose, your thumb being the 'regulator' and the water coming out being the 'fuel back to the tank', the harder you press your thumb over the end, less water will come out, you'll find that the pressure will be increasing in the hose, this is your 'fuel rail'.

In my experience, a good fuel system is essential, even though you're running 'low boost', you can still lean out, causing engine damage. So install a good pump and rising rate reg, so any rebuild you do in the future is done on your own accord, not because you melted the crowns off of three pistons.

[DannyboyDS]

so a rising rate reg should still be installed evenw ith new injectors and fuel pump? I have heard a few mixed answers on this, I will be running 6psi through a charger in june and was just going to use the super six injectors and a 500hp Walbro fuel pump with a tune from Greenfoam oh and the LS1 maf but anyay, will I still need the rising rate reg?

[VT-565]

so a rising rate reg should still be installed evenw ith new injectors and fuel pump? I have heard a few mixed answers on this, I will be running 6psi through a charger in june and was just going to use the super six injectors and a 500hp Walbro fuel pump with a tune from Greenfoam oh and the LS1 maf but anyay, will I still need the rising rate reg?

It's pretty simple, if the fuel can keep up with the amount of air going into the engine, then you don't necessarily need one.

Here's my take on it;

If you have a fixed regulator, set for arguments sake at 50psi, then that is constant rail pressure, even at idle. The ecu as I understand can alter the injector opening times to vary the amount of fuel that way, but this is limited.
This is where a rising rate reg comes in, it increases rail pressure as the boost (re: need for fuel) increases. So you can have a relatively low, easy to tune rail pressure at idle, but have the rail pressure there for the injectors when the demand is high.

Is this incorrect? please correct me where needed, as I'm a bit of a carby convert lol

[immortality]

foam will suggest you use the stock regulator and get the correct injectors and fuel pump. if using a rising rate regulator it becomes very difficult for him to do you a tune (because calculating fuel flow becomes almost impossible)

rising rate regs have there place but i don't think a modern efi system is one. fuel injectors work best at a optimum pressure, VN era injectors had a very narrow range later model injectors have a better working range. fuel injector create the most efficient spray pattern when it's within it's normal working range, you you go outside that range it's going to effect the spray pattern which is going to effect fuel atomisation which effects fuel burn and AFR's, i'm sure you can see where i'm going with this. one thing you need to realise is that doubling the fuel pressure at the fuel rail does NOT mean twice the fuel delivery through the injector. also, when increasing fuel pressure, the injector has to work much harder to lift the pintle of the seat to let the fuel pass through which means a reduced life span for the injector.

most of the guys here who have play'd with home turbo setup and rising rate regs all eventually decided to convert to a standard fuel system and use a 2bar tune from foam. in the long run it's probably cheaper and safer for your engine.