Power Boost Valve

[ticktickboom]

again upon browsing the many elise parts available on ebay, i found this. is it as good as they crack it up to be?

FSE POWER BOOST VALVE FITS LOTUS ELISE 1.8

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0293196333

[campbell]

Well I am no expert but unless you already have a car which can draw excessive amounts of fuel, and has been proven to be strangled by not being able to with the standard fuel regulator, then this is utterly pointless.

Technical Dept will be along in a mo to provide more accurate views, naturally

I say "avoid". Depending on the state of the engine tune there are better ways to spend your money. Not least some tuition. You should have seen the difference in performance extracted from my car at Donnie, depending upon who was driving!!

[ticktickboom]

indeed, trying my best to learn what i can but a lot to get the heed around considering i know very little about the workings of a car.
wasnt really interested in purchasing said item, just curious to know what others think of it.

after doing a search, the only way to find out is ask, but apologies for the n00b questions.

[robin]

It's just an increase in fuel pressure; fuel flow through the injector is proportional to pressure across the injector - so if you need more fuel into the engine, you can either increase injector duration or increase fuel pressure or both.

On the idle and at steady state cruise, the engine management computer (ECU) is able to tweak fuel injector duration to get air/fuel mixture "perfect" for emissions (and, sort of, economy). It does this using feedback from the O2 (aka lambda) sensor in the exhaust pipe, increasing mixture if lean, reducing mixture if rich. This is called "closed loop" running.

On full throttle, or fast throttle opening, the ECU goes into "open loop" where it just uses the injector durations that were mapped against engine load/engine speed and current climatic conditions.

So if you fit one of these, it won't make any difference to closed loop running (provided you keep the extra fuel pressure within reason - e..g 3.5bar). But it will increase fuelling by, approximately, the ratio between new and old fuel pressure when running open loop.

If your engine is standard tune, or close to standard tune (i.e. air filters/sports exhaust/decat) it is pointless and actually counter productive (the mimxture will be too rich at full load/full speed).

If your engine is moderately tuned (head work, valves & cams) and running standard ECU, you might decide to fit one of these if it's running a bit lean at the top end; you would maybe want just an extra 0.1/0.2 bar, just to keep the mixture safe at high RPM, without giving up too much in terms of economy (it's always going to use more fuel this way, never less).

If you engine is heavily tuned such that you're beyond the limits of standard ECU you might decide to increase fuel pressure to squeeze a bit more out of injectors and fuel pump - at 3 bar the fuel pump is probably limited to around 190; the injectors similarly limited on S1; on S2 they are narrower injectors (better economy) and are limited to a little less at maximum duty cycle (90% or so). If you've reached the limit of injectors or fuel pump, increasing the fuel pressure can help.

Cheers,
Robin

[ticktickboom]

cheers for that Robin, thanks.

[campbell]

after doing a search, the only way to find out is ask, but apologies for the n00b questions.

no no, don't apologise, we all had to learn some way and many of us have done just what you have...and what did I say about Tech being along in a minute

keep em coming!