3.5bar fuel pressure regulator - a good idea?

[al_roethlisberger]

Perhaps this question is a little late(although I posed it briefly here once before in another thread), as I've already got the 3.5bar fuel-pressure regulator installed in the fuel circuit of my "balance tube" project, but hey... I thought I'd ask anyway

 

 

Anyway, a while back I was talking to Ken Zeller at Evoluzione.net about some of his aftermarket accessories, one of which was an adjustable fuel-pressure regulator kit for the V11.

 

I asked him why one would want this kit, and he said that his tests showed that once the intake and exhaust was opened up on these bikes, increasing the stock fuel pressure to about 50psi(~3.5bar) over the stock 3bar unit optimized performance. He also noted that often the OEM system was pressurized a tad under-spec.

 

So, what with all my mods... exhausts, crossover, pods, and head-work... and was needing an external/remote fuel pressure regulator for my balance-tube project anyway, I got a Weber 3.5barcartridge(I can change it back and forth to 3bar with the cartridge from the OEM unit) regulator.

 

So here's the question: Is there any risk to the injectors, or otherwise to the fuel system or performance by using this 3.5bar regulator? Just a double-check/second-opinion troll

 

al

[Cliff]

There would be a greater risk of things leaking when components wear.

 

I can't see any benefit to using them unless you were unable to get the ECU + PC to put in enough fuel.

 

Possibly the atomisation might be finer at higher pressure.

 

You could have the same problem as putting in oversized injectors. The smaller pulse required makes adjustments coarser and could affect idle stability.

[al_roethlisberger]

Good point Cliff, and Will Creedon had some similar comments on the Wildguzzi forum.

 

What I think happened is that as I recal Ken at Evoluzione was not(and may still not be, I have no idea ) a big fan of the PCIII, so I think was using increasing pressure to grossly enrichen fuel across the board. This may have crudely given some performance enhancement without having a PCIII or remapping the ECU.

 

So I'll sleep on it tonight, but I think I might just install the 3bar cartridge from the OEM regulator into my remote Weber regulator body.

 

al

[Guest Fonzarelli]

I can't see any benefit to using them unless you were unable to get the ECU + PC to put in enough fuel.

 

Possibly the atomisation might be finer at higher pressure.

 

Having greater atomization would be the number one reason I would increase the fuel pressure.

 

Better atomization, better burn, better torque. The smaller the fuel droplet size, the more energy can be extracted from the charge.

 

The difference between the Weber and Matarelli is only about 7-8 PSI. I do not believe that this could cause any collateral damage.

 

Although you will not hear this from many people, a properly set carburetor will produce more midrange and top-end power than (most) fuel injection. The reason being that a carburetor does a superior job atomizing the fuel. Obviously, fuel injection is much better at startup, warmup and making compensation for temp, humidity, and altitude (daily driving).

 

Better atomization is the key.

 

Fonzarelli

[al_roethlisberger]

Indeed, that is one potential positive that has been mentioned.

 

But while posting this question, I also looked into our fuel-pump, and from what I could tell from the Weber site, our pump is only rated at 45psi anyway. So I don't know if it could reliably and regularly support the 3.5bar(~51psi) high pressure supply.

 

That in combination with the potential issues Will Creedon, Cliff, et al... have supplied, I think I'll just reinstall the 3.0bar cartridge and go with that. After all, it seems like everyone else who has never touched their regulator is doing just fine with cams, high-comp pistons, etc....

 

Thanks for all the feedback!

 

al

[jtucker]

Al, I think the benefit of Ken's adjustable kit is that it lets you dial in the pressure if, by chance, it is not up to spec. The pump may be rated at 45psi, and you may have the 45psi regulator cartridge, but the question is, how well do you trust that regulator? If memory serves, Ken had a big issue with the Aprilia systems, in that their actual pressure was all over the board when compared to what they were *supposed* to be.

 

I bought his modifier and guage kit, but as my bike as been on the bench, I haven't had a chance to experiment with it.

[al_roethlisberger]

Yeah, I understand... but he also wasn't a great advocate of the PCIII, so from that perspective I can see "tuning" fuel-pressure versus remapping the actual pulse.

 

From my conversations with various folks, I think I'll stick with the standard fuel regulator, and tune the injection to that constant.... at least for now

 

After all, the regulator is just a spring, and even if it's 43psi, it should be a constant 43psi, and with the PCIII I think one can tune to that.

 

...and I'm a bit leery of that "glue in" adjuster.... with all the vibration, heat, etc... I'd hate for it to pop out = fire

 

al