So whose using a rising-rate fuel pump regulator?, Not turbos; or using a cold start valve as a 5th injector? Options

[computers4kids]

Who has played with a rising-rate regulator or adding a switch to a cold start valve to be used as a 5th injector to get a little extra pony power?
Here's one...
MicroDynamics RisingRate Regulators are designed for use with all types of fuel injection systems. Added to standard systems they increase the mixture range for high performance or provide "boost or load enrichment" on both turbo and naturally aspirated engines. Rising-Rate will also give more fuel at the top end without going over-rich lower down the rev/power range.

A MicroDynamics RisingRate Regulator is often the only form of fuel enrichment required for many retrofit turbo conversions and is usually the easiest way to obtain increased fuelling on production injected race vehicles.

Here's one by Bell Engineering $179

Here is an interesting article how to make your own rising-rate pressure regulator from a stock 914 regulator

[Dave_Darling]

Who has played with a rising-rate regulator or adding a switch to a cold start valve to be used as a 5th injector to get a little extra pony power?

Well, that would be awfully nice if you could get more air into the engine to go with that fuel. Otherwise, you're just richening up the mixture, most likely to the point where you get worse power and beyond that.

The only people I know of who did the RRFPR thing and seemed to have it work OK were running boost. Jeff Shyu (Jenny's brother) did that on his D-jet turbo 914. (Yeah, I know--you can't turbo a 914!) Otherwise, it's just a way to richen the mixture with higher throttle settings in a way that is diffcult to reconcile with the way the stock D-jet is working.

The L-jet FPR used on the 1.8 is supposed to keep the fuel pressure at a constant difference from the manifold air pressure, so you get a consistent amount of fuel going in for a given injector opening time. It's one way to remove one of the variables that occurs within the intake system, and probably the most useful when you are designing and/or programming the EFI system.

--DD