FSE Power Boast Valve

[scuzzmcmatt]

I've seen recently on ebay FSE power boast valves, supposed to work wonders...? Anyone tried one before on their chim?

Thanks

M

[GreenV8S]

The name is a bit of clever marketing. What they do is make the engine run richer at full throttle. If there was some problem making the engine run too lean, the extra fuel might be beneficial. But if it was already getting the right amount of fuel, adding more will actually reduce power.

In other words if the engine is set up correctly these things do more harm than good, and if it isn't then it's better to sort that problem out than try bodging it.

[pilgrim13]

Years ago I put one of these on an XR3i (EFi) which was running as it should and the difference was amazing. More responsive, smoother however I seem to remember the standard valve on these models werent up to much and was recognized problem.

[daz the plumber]

if you get the 1:1 fuel regulator it works the same as a standard fuel reg but you can tweak the presure up a little .the rising rate 1:71 are no good for the 14 cux .

[scuzzmcmatt]

thanks for the info, also Has anyone tried the 'Mark Adams Chip' on theirs, i have chipped things in the past with varying results?!

Cheers

M

[daz the plumber]

im considering having my car chipped but i need the know if the fueling is the problem , ive had a few mods nothing drastic . the engine does not run on all eight pistons between 1100 up to 2000 revs then it clears and goes like the wind .the car only does 15 to a gallon and thats taking my time .i don`t mind spending the money but i don`t want to end up with the same problem .is does not sound to bad but you can cruise under the 2000 revs so its missing most of te time .

[daz the plumber]

so what do you think the problem is then < its done 40000 miles . i can`t complain about the performance its just the lumpy bit between 1100 upto 2000

[GreenV8S]

If you get a proper "Mark Adams" setup (rather than just buying a chip) the first thing he does is go over the engine management with a fine tooth comb making sure that everything is working properly. I can't promise that he'll fix all your problems, but I'd say he's far and away the best person to do it.

[blitzracing]

scuzzmcmatt said:

thanks for the info, also Has anyone tried the 'Mark Adams Chip' on theirs, i have chipped things in the past with varying results?!

Cheers

M

In real terms you are very limited to any major improvements you can do on a catalyst car, due to the lambda probes keeping the mixture set for minimum emmissions up to 3400 rpm. Chipping cannot change this region, as long as the base map is near correct. You can alter things above this point with chipping (£400) or a varable fuel pressure regulator,(£35) both best done whilst monitoring power or exhaust contents under load. A lot of the hype about chipping harks back to the pre catalyst cars, when some of the origional Range Rover maps where pretty poor. TVR already rechip the ECU, and certainly the 3.9 map is pretty good. (worth an extra 12 bhp over the Range Rover map). The results from rechipping can be things like better low speed driveability, and better cold start fueling but dont expect a big power gain, this bit has been done already by TVR.

Mark

[vrover8]

A power boost valve is another name for an adjustable fuel pressure regulator. It has a screw on the top to adjust the fuel pressure behind the injectors, when the injector opens more fuel pressure behind it means more fuel is injected in. There are two reasons you won't see much difference on a TVR the first is the fuel pressure is already about 42psi and at 47psi the injector can't open at all which leaves little scope to up the fuel pressure.
Secondly in order to use the extra fuel you have to have extra air and a tvr doesn't really run lean anyway. If you are after more power you will be far better off to upgrade the camshaft and upgrade the cylinder heads and then look at upgrading the ECU after that.

[blitzracing]

Bit more to it than that, the fuel pressure is clamped against the air pressure (or more lack of it) in the plenum chamber, so that the pressure difference across the injector is always consistent however hard the engine in drawing air. A simple variable pressure regulator keeps this ratio between fuel pressure and plenum vacuum fixed. ie. Plenum chamber is 3psi below atmosphere, the fuel pressure is dropped by 3 psi so the factor is 1. Every one is happy as the ECU mapping expects this. The "power boost" (also called rising rate) type increase's or decreased the pressure by a factor of more than one, so when the inlet vacuum drops, (throttle open) the fuel pressure goes up by more than the pressure change in the plenum, hence loads more fuel goes in. Like wise it drops the fuel pressure by more than the plenum change when the vacuum increases. This completely screws up the ECU's mixture control system, and is TOTALLY unsuitable for the 14CUX. A non raising rate variable pressure regulator is fine for small adjustments in open loop fuelling (above 3400 rpm or ¾ throttle).

Mark

[davvid]

I found cleaning the rotor arm and fitting "6" plugs, instead of 7,s helped a little with rough running under 2000rpm,they run a little hotter and were recommended on this forum;since you can't really alter the mixture,I feel the next thing is to make sure the ignition system is tip top.

[daz the plumber]

been on the rolling road today complaining about the rough running between 1100 up to about 2000 and poor fuel consumption (15 mpg)he told me the car is not miss firing and running on all 8 cylinders... then explained its the cam type the car runs very rich untill just over 2000 revs then corrects its self .the car is running very rich up to 2000 revs somthing to do with cam duration and over lap .so i dont know what to do next .i don`t want to spend more money with out a result .tell you the truth im sick of it .he gave me a read out showing something to do with the hydro carbons. any advice thanks

[daz the plumber]

forgot to say the vacume advance as been blocked off

[GreenV8S]

daz the plumber said:

he told me the car is not miss firing and running on all 8 cylinders... then explained its the cam type the car runs very rich until just over 2000 revs then corrects its self

Was 'he' somebody with any experience at all of the Lucas 14 CUX on a Rover V8? It's all too easy to come up with a confident answer but being able to operate a rolling road doesn't necessarily make you competent to diagnose every engine management system you come across.

[daz the plumber]

yes he is ,the rolling road and equiptment tells you alot .if the car is running rich at low rpm this means its not able to burn the fuel .

[That Daddy]

Daz,you have got issues with your car and it aint Cam related,they under fuel below 2k not overfuel,i have the 5.0 cam in my 4.0 and it runs lean below 2k so not quite sure why your cam as come into the mix,this is why you hear about the dreaded lean mixture lurch mentioned from time to time(Blitz racings chosen subject)without going into detail this seems to indicate you have problems elsewhere you mentioned high HC a by product off overfueling, have check your air mass meter/Lambda output performance maybe you can borrow from another member?getting a volt meter on your Lambda probe outputs would be very helful in the diagnoisis,hope you fix it soon i hate to hear owners getting pissed off with these cars when it should be giving you lots of enjoyment

Edited by That Daddy on Thursday 24th July 22:48

[daz the plumber]

well i don`t know what to do next , the dyno shows the mixture to rich thus useing alot of fuel at low revs then running perfect after 2100 .the only thing i dont pass is a petrol station !

[GreenV8S]

daz the plumber said:

well i don`t know what to do next

The logical next step is to get somebody who knows the engine management system inside and out to track the problem down. It needn't be expensive, but you do need somebody who really knows what he's doing and not just somebody willing to have a guess.

[daz the plumber]

can you put me on to some one who knows