What is the difference between these items?
I know the RKSport FPRiser is installed in conjunction with the OEM regulator, but why? Wouldn't it be more efficient (not to say economical) to just install an aftermarket Adjustable Fuel Pressure Regulator instead?
Also, can you gain anything by using the RKSport Fuel Pressure Riser AND an adjustable Fuel Pressure Regulator? (My guess is NO, but I thought I'd ask the 2nd question anyhow...) LOL
Thanks in advance...
L8r...
___________
. . . . jb . . . .
...Son Fire!
*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me
well, fuel pressure risers increase pressure after the stock regulator, as said. but it is adjusted with a screw - no vacuum lines. and not the most efficient design.
an aftermarket regulator usually has a vacuum line that opens / closes a diaphram regulating fuel pressure (think of how much fuel you need at idle, and then at 5,000 rpm. ) your OEM is set up the same way but isn't adjustable, it should hold pressure around 45psi. you can adjust the aftermarket (AEM, venom, holley) to whatever pressure it can go to. but you shouldn't expect the gain that you expect.
the PCM doesn't control fuel pressure, it does control the injectors (duty cycle- how much fuel is being injected) at a higher pressure there will probably be less "on" time so you would be injecting roughly the same amount of fuel. however this leaves a lot of overhead for those "testing the speed governor" times. since you have more pressure the PCM can inject the fuel it needs with less of a duty cycle, meaning you aren't likely to over run your injectors with a 98% on time.
higher pressures can also be a good defence against vapor lock-- this is when the gas in the rail gets so much heat it starts to vaporize and the engine starves for fuel, this is more common on carbs and low pressure TBI systems, but not impossible on a MPFI engine.
in a closing, using the rk riser would be like putting ebay coilovers on stock struts and slamming it 3" i saw the rk unit and it looks like the main purpose of it's design is for people with no mechanical ability. save up and get the good stuff.
chapter10,
Thanks for the explanation.
It does seem more elegant (and logical) to adjust the fuel pressure AT the regulator via vacuum. But RK claims that,
"The large center section (black) on [our RKSport Fuel Pressure Riser] contains the double diaphragm. Most aftermarket fuel pressure regulators use a small inexpensive diaphragm, which reacts slowly to pressure variations. This can cause a loss of mid range torque, and flat spots in the power band. Our FPR incorporates a full 2.5” double diaphragm, which not only reacts quickly to conditions under load, but will also provide a 2:1 pressure increase when under boost, ensuring a smooth transition."
While I don't know anyone personally who has used or installed one of the pressure risers, I have heard, however, that it does initiate a very quick response on the throttle.
Do you think that RK's claim to "most aftermarket regulators" fall flat then? I find it hard to believe that an adjustable FP Regulator made for a Vette or other higher performance car would not perform up to that same standard...
I've seen Adj Fuel Pressure Regulators for less than half of what RK Sport wants for their competing model, too.
That being said, RK does have a more simple solution -- or so it would seem...
(BTW, nice comparison of eBay coilovers and stock struts! LOL )
L8r...
___________
. . . . jb . . . .
...Son Fire!
*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me
^^^
L8r...
___________
. . . . jb . . . .
...Son Fire!
*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me
