E30 Zone

I have a mate who has just fitted one of these to his 635csi and he swears it has made a noticeable difference to responsiveness and performance.

Anyone tried it or have any thoughts on how it would work on an L-jetronic M20 motor?

There is a ready made adaptor available in Oz so is easy and cheap to do if it is worth it at all.

Thanks
David

Waste of money imo.. Nice way to get some bore wash. If it makes a noticeable difference there was something wrong in the 1st place

Jhonno wrote:Waste of money imo.. Nice way to get some bore wash. If it makes a noticeable difference there was something wrong in the 1st place

Not so (in my view anyway).
It's simple physics, really - if you increase the pressure in the fuel rail, more fuel goes through the injectors in any given time.
There is, however a diminishing return the more the flow increases, due to frictional losses through the nozzle. Eventually the extra pressure required to move any additional fluid through the nozzle will rise exponentially - at that point, deffo no gains to be had without changeing the injectors.
SO in a nutshell, the mixture will be richer if the fuel pressure is higher than std.
I know this works, as my sons Peugeot 205 which at that time had been fitted with an Mi16 motor with modded head and cams would get chronic weak mixture / detonation at high revs / full throttle unless the pressure was turned up to 4 bar iirc.
HTH
Kim

Sorry Kim but I have to agree with Jhonno on this one. I'm in full agreement with regard to increased pressure resulting in increased fuel flow through the injector (in fact I have an adjustable regulator on my own car to achieve exactly this). What I do question, however, is the benefit of decreasing the AFR (by increasing the mass of fuel injected). On a car stock tuned for economy there may initially be some increase in performance (at the expense of economy) but after that you are just wasting fuel, pumping out excess hydrocarbons, and washing your bores.

BTW, I do not doubt what you say WRT your sons car. But by your own statement your sons engine was modded and thus required the extra fuel to prevent it from running lean. I only point this out because I think possibly 95-540iLE's post refers to a stock engine with no mods, which (unless it is tuned to the extreme of economy) should not benefit from being run rich.

As for my own adjustable FPR, I locked it down after the mods were completed and the engine tuned.

GeoffBob,
Yes I agree, but as you said, on a car tuned for economy (and best emissions) a richer mixture will normally result in improved pickup - but yes, at the expense of fuel economy. I had assumed (perhaps wrongly) that the car was to be used for track work (we're in the motorsport forum after all) and economy and emissions weren't high priority)
If a cone type or other high efficiency air filter were fitted, raising the fuel pressure could be used as an admittedly crude method of correcting the mixture strength.
I think we're holding the same stick here, just beating each other with opposite ends!!

Kim

Hi guys - interesting discussion. The motor is stock Hartge H23 - so some head work and cams.

And yes, I use it for limited club based track work and the occasional competitive hillclimb. Very rarely used on the road as have many other cars for daily driver use.

Kimbo, interested in your last post, as my mate has also matched the regulator with a cone type air filter on his 635Csi ...

Well in that case then I fully agree, an adjustable FPR will make a difference, but only because some modification has been made to the engine that enables it to draw in a greater mass of air (due to a better breathing filter, for example) and thus the mixture is required to be enriched in order re-establish the correct AFR.

David, what you have to keep in mind is that the adjustable FPR is not an improvement by itself (as I think your original post questions), but can be a useful tool for correcting a lean mixture (across the range of rpm) as a result of some modification that results increased air intake. An adjustable FPR regulator is of course no substitute for a proper re-tune since any modification to an engine seldom results in an identical shift in the AFR across the whole range of rpm. For example, increasing the lift and/or duration of a cam could leave you dangerously lean at certain rpm if the issue of tuning is left unaddressed. Solving this problem by increasing the pressure to the fuel injectors would result in the engine running rich at other rpm and is thus not an ideal solution.

I would honestly advise that you first establish that your AFR is on the lean side of stoichiometric before you opt to enrich your fuel mixture. Driving the car on the track with an AFR gauge fitted is an excellent way to decide for yourself if you would benefit from fitting an adjustable AFR.

The point I would make Geoffbob is the fact this car came out the factory with these mods, and therefore is very likely setup for them already, by Hartge themselves..

Jhonno wrote:The point I would make Geoffbob is the fact this car came out the factory with these mods, and therefore is very likely setup for them already, by Hartge themselves..

second that!

If you don't belive it, fit an AFR gauge to check the mixture.
Raising the fuel pressure will raise the AFR's over the WHOLE map, not just iron out a flat spot.