Shpubs' views on fuel pressure regulators?

[dickymint]

Sorry Steve if this post appears to be drawing you out into the open! But there has been a few posts about rising rate regulators lately.
Your "Bible" (crosses himself and sprinkles Holy water) Suggests that this is a good fit, and indeed it transformed my 350
I noticed that MikeB's 450SE (£8000 rebuild) runs on the standard 350 Lucas non adjustable and thought this to be a bit odd as my SEAC and most other bigger Wedges have the adjustable type (but non rising rate).
Your views would be much appreciated especially as it is currently quite topical.
Cheers Dicky

[GreenV8S]

Mind if I stick my 2p in while you're waiting for Steve?

Rising rate pressure regulators are a bodge to give you more fuel at higher throttle openings. More fuel will tend to give you a sharper throttle response, and it may give you more power if the engine was lean to start with or you had detonation problems, but if you give it too much fuel it will actually reduce the power output (as well as coking the engine up and increasing wear).

Rather than just giving it more fuel, it is better to get the fuel map set up to give it exactly the optimal amount. This means putting the engine on an dyno or rolling road, which is moderately expensive, which is probably why people do still use adjustable and rising rate regulators as a very crude DIY way to alter the fuelling.

Fuel injectors are designed to work at a particular fuel pressure, and going significantly higher or lower than this can mess up the spray patterns. If you're having the engine set up, your best bet is to get a good quality regulator which runs at the right pressure for those injectors and then leave it alone. The fuel map will then deliver the correct amount of fuel at that pressure.

Consistency is important; if your pressure regulator remains consistent then there is no need to be able to adjust it to correct the fuel pressure. The FSE valves in particular have a reputation for losing the ability to regulate properly with age. This makes your engine run lean, which is very bad news.

Hope this helps, now over to Steve for the details ...

[jchase]

I agree with you Mr GreenV8s, all a riser will do is give you really bad fuel economy at part throttle, whereas what you really want is to run a bit rich when you stick yer foot down, which must be a teeny weeny change in the ECU software, after all [the ECU] knows the throttle position.

I think Steve is a fan of the rising rate regulator, at least he was when he wrote the wedge bible, but we won't keep him to it will we? Steve ?

Adam, you have a rising rate regulator dont you? - what do you think ? All that extra money you spent on fuel, you could have bought a supercharged wedge...oh you did !!

[chunder]

Richard,

Good post - I was thinking of fitting one and was trying to work out exactly what the benefits really were. Seems to me that if the standard one is working ok and regulating pressure to keep a constant differential between fuel rail and manifold then you're just going to end up with an overly rich mixture during heavy throttle applications.
If the standard one gives a good mixture at idle, cruise and full power then what advantages does the rising rate regulator provide ?
Maybe it would help a car that's running lean under full power but otherwise I can't see where there is any power gain or advantage.
Would also be interested to see a response from someone who knows more than me (that's pretty much anyone I guess) in order to try and understand a bit more about any benefits.