(15-10-2012, 09:51 PM)Pipps Wrote: Is it still worth doing the fuel pump and sensor mods, while keeping a standard turbo?
It's possibly worth doing.
Basically the 1800bar sensor lets you read much higher pressures, out to 1800bar vs 1500bar obviously.
The problem is the standard pump can't make high pressures AND high injections because the pressure is a function of restriction.
Think of it like a house tap.
Turn it on more as the rpm rise, and that is how the pump delivers it's fuel.
The injectors are like you putting your finger over the end. The less you let past, the higher the pressure it squirts out.
At low rpm (near high torque at 2000-2500 rpm) the tap is only half open, but you want BIG injections for loads of torque, so your finger is right off the pipe, and the final injection isn't really a squirt at all, more a dribble eventually.
If the fuel can't inject at high pressure, then it takes longer to get the amount you want in there. You can't inject too early otherwise you are injecting before the exhaust valves shut.
You can't inject too late otherwise you are pumping fuel in after the piston is past the top and it burns inefficiently and very hot (smoke, burnt turbines, etc)
Thing is, at low rpm where the tap is open only a bit, pistons move slower, and so you have a bit more chance to inject fuel any way.
Having an 1800bar sensor here is pointless because without a better pump, the rail pressure can't go higher really.
In theory on a stage 1 you could run higher rail pressure because injections are smaller, so the finger is more closed over the tap, so you get more squirty pressure.
Problem is you don't really need more fuel in a stage 1 as temps are already too high really. You can easily get enough at the 1500bar limit on a stage1.
So the main benefit is at higher speeds. The engine is running faster, injection amounts start to fall off too, so you get a slight gain here for more rail pressure.
Also as the speed is higher piston speeds are high and you want to finish injections sooner (a short duration)
So at maybe 4000rpm you can probably run a load more rail pressure, get better combustion and a bit more power, less waste EGT etc.
The 1800bar sensor is a worthwhile mod.
I've even sent people maps with it set for the 1800bar sensor simply because it was a cheaper replacement than the 1500bar sensor hehe.
The better HP pump in combo with it, well obviously you can turn the tap up harder everywhere and that just means you can run more rail pressure everywhere, and that generally means you can get more power by injecting more fuel in the same space of time as before.
Downsides are parasitic losses may be marginally higher so economy might suffer. For any possible gain you might get on one hand, you pay on the other.
From what I've seen the R70 doesn't have the de-activator for example.
All depends what you want I guess.
I say outline what you want, and then spec and budget it, and then do it.
If you want an 1800bar sensor then get one. But you can easily hit 175bhp/270lbft without one with a hybrid turbo that moves the torque curve further up the rev range (where the tap is open more to start with!)
However you look at it we see stage 2's making 290lbft or so on standard turbos, and we see hybrids make up to 180bhp on standard bits, so it's clear that a standard pump/sensor can run fuellings for 290lbft/175bhp or so. We just need the air! (and a good condition oem pump/fuel system)
Dave