MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - FSE adjustable fuel pressure regulator / janspeed

Following on from the RR post, where can I get an FSE fuel pressure regulator? How do they work? Could I fit it myself (being very incompetent - did manage the 52mm TB but thats easy)? What sought of power gain can I expect?

Re the Janspeed manifold , how much? Is fitting it a big job? What power gain?

Any views on Motobuild?

Thanks
marc hanson

I have the Janspeed 4-2-1 manifold fitted on my modified 1.8i. It is a DIY job but only if you have got lots of time a cool temper, tools and strength. Plus you need to heal quickly as you will definably take the skin off your of your knuckles.

Have you ever taken the CAT off you car? If not the job will be hard as that is one of the first things you need to remove.

It took me two weekends, partly because I did not have a 17mm deep socket. Even then I needed help from a friend to hold down the old manifold whilst I wrestled with he Lambda sensor.

Was it worth it? Yes I think so. I wanted to fill a gap on my toque curve and it did that. I don't really think it added much if anything to my bhp. As far as cost goes have a look on Mike Satur's web site.
Steve Ratledge

Marc, we missed you on Sunday?

Regarding the FSE - well, we're not allowed to use this as it is not a standard fuel rail item, and hence a no-no as far as I know for standard class sprints. But the question is more: "is my car running lean with my current modifications?"

If the car IS running lean, then you'll definitely gain more power by running a higher fuel pressure through the standard injectors. How much depends on how lean the engine is running at peak power. Dave saw a 10% gain from 'tuning up' his FSE.

However, if the engine is running stoichiometrically already, then there is absolutely no benefit in fitting a FSE over standard. A waste of money.

I've found this when I tried a richer fuel pressure regulator in my car - and Thierry has shown this very eloquently with RR with an FSE - see http://www.mgf.ultimatemg.com/fuel_rail/FSE_fuel_regulator.htm for Thierry's figures...

Bottom line is that you need to know where your starting point is and the best way to achieve this is on a rolling road equipped with a exhaust Lambda.
Rob Bell

Rob

yes couldnt do Silverstone as my youngest was having her christening. Sad I missed S as I imagine it was fun as ever. Still, doing Goodwood this saturday with the ACSMC series. BROOM!

As to the FSE, not sure I follow you. If the car is running lean can this be adjusted without needing to get the adjustable regulator? I will definately do a RR session (proably at the end of the season)so it may have to wait till then.

Doesnt sound like the 421 manifold will do much to my times...
marc hanson

>> yes couldnt do Silverstone as my youngest was having her christening. <<

D'oh! I guess it would be regarded as a poor show not going to your own daughter's christening... LOL

Good luck at Goodwood! :o)

>> As to the FSE, not sure I follow you. If the car is running lean can this be adjusted without needing to get the adjustable regulator? I will definately do a RR session (proably at the end of the season)so it may have to wait till then. <<

Yes - by using a standard fuel pressure regulator that has been 'squeezed' a bit. :o) Mat Smith does these as he has a pressure gauge and a vice! I tried a 3.3bar FPR out of interest on my car, but found that it hopelessly over fuelled: power down 10bhp :o( Hence the reason for knowing where you are starting from.

We're thinking of another RR session at Emerald this time some time in September if you are interested...

>> Doesnt sound like the 421 manifold will do much to my times... <<

Torque wins races, as I believe Gordon Murry once said - so yes, a 4-2-1 manifold will definitely help... Hmm, why am I telling you this??? ROFL!

If you are asking then yes, I am planning on fitting one of these in the near term... :o)
Rob Bell

However, if the engine is running stoichiometrically
already, then there is absolutely no benefit in fitting a FSE over standard. A waste of money.
-----------

I beg to differ. That's not true IMHO

Stoichometry = 14,7/1 (Air/Fuel Ratio)
MAX Power = 12,8/1

So :
1) Yes there is power to gain even if your current AirFuel Ratio is stoichiometrical (huh) on the standart car.

2) You will always gain a huge amount of torque when exchanging the Fuel Pressure regulator, even if you don't have it adjusted 100%.


The best way to fine tune the FSE, is to fit a Widerange lamda sensor to your car, and have a AF Ratiometer inside the car. Then adjust it to your liking.

PS. Good and complete Widerange kits start as low as 400$, you might even replace the existing lambda sensor with the widerange one and still feed the ECU the narrow range data. Best of both worlds: You can monitor A/F ratio at 10hz without any drilling happening to your exhaust system, AND you have realisticaly setup the FSE (realisticaly in the sense of realistic wind air movements, not the 50KM/h the RR fans can simulate.





T

Addendum:
I will have to research the 12,8/1 (not sure about the specific value) but I am sure that max power doesn't happen at 14,7/1 but on a richer fuel ratio.
Thierry

There we go :
We mentioned the stoichiometric air-fuel ratio (14.7:1) that is the ideal ratio for lowest emissions, but this isn't the best ratio for power. It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1.

http://www.carcraft.com/techarticles/116_0402_tune/
Thierry

Using a WR Lambda in place of the standard Lambda is an interesting idea Thierry - but $400 is quite a lot of money to spend on something that you'll only ever use once. But I'd definitely find it useful! :o)

Peak power is typically obtained in a range of 12.0-13.5:1 - in the case of Dave Livingstone's car, that ratio was 13.1:1@7000rpm - so your figure of 12.8:1 is certainly not far off that mark we saw at G-Force. The 14.7:1 figure is the perfect air:fuel mixture for optimal efficiency of fuel burn - although engines often run leaner than that ("Lean burn") to improve fuel economy.

The point that I am making is that there is only ever any real point in changing the fuel pressure regulator IF the fuelling is way off when the engine is in open-loop mode. In closed loop, MEMS will revert to optimal stoichiometry according to conditions irrespective of fuel pressure.

If the engine is running too rich or too lean at peak power, then great, you can see big improvements to power by altering fuelling.

However, with a standard engine these conditions (of over or under fuelling) are unlikely to be seen.

Consequently, spending over 100 quid on an FSE is unlikely to see you gaining much in the way of power - so is this money well spent? £100 for say 1 bhp value for money?

The whole question of fuelling is naturally much more complex than we've delt with - and interestingly, the optimal stoichiometric ratio seems to vary according to conditions. From experience with my 3.3bar FPR, which ran far too rich at peak power, there were definite gains in power and torque at lower engine speeds.

In fact, on my engine, optimal stoichiometry for power/torque at 3000rpm seems to be around 12:1 mark (more RR needed perhaps?)...

Which brings us meandering around to another point: fitting an up-rated FPR is something of a blunderbus approach to fuelling. Upping the fuelling at peak power can ruin the fuelling at other points in the power curve. To get optimal stoichiometry and therefore power throughout the engine range, you really need to map the fuelling requirements (as MEMS already does - but you may want to push the envelope a little further). Of course, to do this you need access to a rolling road and equip your car with a programmable ECU - and in this case, an FSE is somewhat unnecessary...
Rob Bell

but $400 is quite a lot of money to spend on something that you'll only ever use once
--
Yep, but you may sell it on ebay afterwards :) So in the end it may cost you 70$

I see you are sometimes using "stoichiometry" in a general sense, as found in the dictionary, hence the confusion.

14,7:1 = Stoich = Lambda 1 = cat works best in these ranges.

Of course the best way is to alter the ECU, but for us VVC owners there is no programmable one, hence I (and a few others) can only use the FSE to enhance the fuel mixture.

The FSE can ruin the power at other RPM levels while giving max power at some others, but just take a look at the BEFORE/AFTER FSE graphs of mine, there is no drop anywhere below the standart Fuel pressure regulator, in fact it always way higher over the whole range. It could be that as the FSE uses the same "underpressure" pipe as the standart FPR it reacting the same way. In mathematics you could say :

x = pressure at given throttle position/rpm range

Standart FPR : x
FSE : x + y (where y is the PLUS in pressure)







Thierry

>> I see you are sometimes using "stoichiometry" in a general sense, as found in the dictionary, hence the confusion. <<

Ah - I didn't think that we had fundamentally different views on this subject Thierry! :o)

>> Of course the best way is to alter the ECU, but for us VVC owners there is no programmable one, hence I (and a few others) can only use the FSE to enhance the fuel mixture. <<

There is now: http://www.emeraldm3d.com/em_projects_VVC.html :o)

There seems to be good gains achievable even with an effectively standard engine, which is very encouraging. But whether fitting an M3D and then RR set up costs represent good value for money against a relatively cheap FSE I don't know - but is certain to represent the BEST option.
Rob Bell

There is now: http://www.emeraldm3d.com/em_projects_VVC.html :o)
---

AAAh : ;) Finaly
Thierry

getting a bit too complex with your stolly whatevers! Yes Rob, would be keen on the RR day in September. Presumably at that someone wil be able to tell me if my car is running lean or otherwise?
marc hanson

The experience on my car was the same as Thierry - gains all through the power and torque curves, with the peak figure (7000rpm) up 10bhp and pretty much right on the 13:1 ratio.

Interestingly, my mpg has noticeably improved by about 4 mpg - an unexpected and additional gain :-)

Dave Livingstone

>> Presumably at that someone wil be able to tell me if my car is running lean or otherwise? <<

Yep! :o)

>> Interestingly, my mpg has noticeably improved by about 4 mpg - an unexpected and additional gain :-) <<

Now that is unexpected! :o) Driving style change or just improved efficiency do you think Dave?
Rob Bell

>>Driving style change or just improved efficiency do you think Dave?

What do you think Rob ;-)

Noticeably better mpg - I'm driving just the same!
Dave Livingstone

LOL! So you've got a fuel efficient road rocket then? :o)
Rob Bell

This thread was discussed between 27/07/2004 and 29/07/2004

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now