Rising Rate Fuel Pressure Regulator

[dmurrell]

Does anyone out there in Lancia Land have experience modifying the EFI setup on Betas with a rising rate fuel regulator? I need to find a way to get a little bit more fuel into my modified engine.

Thanks in advance,
Dave

[A1.6HPE]

Hello,
A few years ago I saw a Delta that Barry Waterhouse had installed a Beta EFI engine with a turbo charger. To get enough petrol in they had fitted a fifth injector in the middle of the plenum chamber so as to richen the mixture. As you probably know the Bosch ecu cannot be viably re-programmed so they had fitted a simple switch to energise the extra injector. I think that the switch connected the fifth injector to the other injectors so that it fired in synch with the others (Bosch LE2 is a non-sequenced system, the injectors all fire simultaneousy).

Leo

[VX131R]

There are a load of my customers in turbo japanese import circles that use them. Personally I don't like them, nor would I use one but they are a cheap and easy way to gain more fuel. There are a lot of pro's and cons for them, and lots of peolpe argue that they are the best thing since sliced bread.
Things to remember:
There are different rates, 1:1.2, 1:1.5 etc 1 to 1.5 is the most common I see.
They apply 1.5psi of additional fuel pressre to every 1psi of boost pressure to the existing standard fuel pressure. eg( for a 1:1.5 reg )
so if you have 45 psi std pressure and 10psi boost, at full boost you will have 60 psi fuel pressure.
with a 100 cc injector,(wide open) in theory you will get 115 cc.
BIG NOTE: the additional fuel pressure will mean it is now harder for your fuel pump to supply fuel, and its flow will drop off. You will need to upgrade!
You now have 60psi in your fuel lines, will your connections hold????

They can prove difficult to settup, because the rising ratio works in both directions, ie when the intake is under vacum, fuel pressure will lower at the same rate, making injector flow very poor.

Dyno engine tuners hate them, the ecu cant see fuel pressure so it is very hard to programme the ecu fuel map when you have one fitted.

Some will be better at this than others.

Most guys use them when they want to keep a factory ecu, and chip it or keep it standard.

Personnaly I would use an extra injector, and a aftermarket controller.

I wouldn't rely on essentially what is a basic mechanical device to supply the very crucial extra fuel at the the point where you relly dont want it to lean out and go bang!
Andrew

[Will]

On the advice of a fellow enthusiast, I tried one of the SPA units on a pjoject and found it less than satisfactory for many of the reasons Andrew stated. I agree with him on most points except the inexpensive part, the SPA unit was about $300.
If your modified motor is turboed or supercharged, then you really need a new ECU if you are getting over 5 or 6lbs of boost. If it is still N/A and the modifications are cam, port, and valve related, you may be able to squeak by with stepping up an injector size.

BMW's use larger Bosch injectors for several models, and the scrap yards here are rife with them.
Another thing you can do is open the meter bypass screw and also back the flapper spring off a full three notches. Finally, you can use the air temp sensor circuit (sensor is in the meter) to fool the ECU into thinking you are pulling in colder air, this in turn will cause it to increase the duty cycle to the injectors, but I don't know at what point it stops or is overidden by lambda control.

For a little bit more, you can get one of the "piggyback" type controllers that gets used for supplemental fueling, these run about $400 and are the best choice short of ditching the ECU in favor of a transplant.

(all statements IMHO, and no offense meant to SAAB owners)
-Will