Altering Injection Feed Layout

Bitza · 03-10-2020, 07:07 PM

Hi all, anyone got any comments to make about my current mod. The bike is a 94 chassis with a DS lump, currently using the throttles/injectors off a 2001 900ie with the standard period feed & return fuel line system. Now I always had a feeling that the bike ran better just after filling up with fuel, it seemed that little bit sharper. I fancied that if it wasn't simply my imagination, then it would probably be down to the new fuel being cooler and which subsequently warms up. So to lessen the opportunities for heat transfer, I've just got a low slung oil cooler and I'm going to get rid of the fuel return. Easy to do because I use a non-ducati fuel pump that comes in both return & returnless forms. So the big questions are first will it work no problem and might it also help lessen any heating effect? On the bright side I will at least shred a bit of weight and will also open up air flow a bit too. As always all comments most welcome, Bitza

Mr Gazza · 03-10-2020, 07:28 PM

I don't really see your logic. Surely the new fuel won't be any cooler than a half a tank that's been sitting in the bike since you last used it?
I can't see the fractions of a degree difference in fuel temperature making a perceivable difference to performance. I've never noticed anything like that on my 900ie.

If anything I think it would be down to the additional pressure in the new head of fuel, but then I shouldn't think it would alter the pressure in the fuel rail after going through the pump, unless your pump works in a different way to a standard one with regulator in the rail?
If temperature is really what is giving the effect you perceive, then maybe an insulated fuel pipe up to the injectors and then a return via a small cooler such as is sometimes installed in oil lines of dry sump systems?

I can see how the low slung oil cooler might keep warm air flow off the top of the engine and fuel rail, but I would be worrying about a stone going through it, unless of course you have a guard.

Just playing devils advocate here, I actually admire your experiments and projects..

Hopefully an interesting debate will follow..

Nickj · 03-10-2020, 08:24 PM

I suppose cold fuel would have much the same effect, though to a lesser degree, as feeding cold air to the motor.

Cold fuel certainly works with diesel -> https://www.sciencedirect.com/scienc...43967115000112

I can't see why there wouldn't be the same effect with higher flammability fuels like petrol

slob · 03-10-2020, 09:19 PM

Sounds like a load of work for very marginal, if any, gain.
But very happy to be proved wrong ;-)

edit: If you think fuel temperature is making a difference, and cold fuel is denser than warm fuel, could it be that the bike is running a little lean at ambient temp?
Possibly due to a better breathing air filter. What do the plugs look like?

Bitza · 04-10-2020, 09:08 AM

A load of effort for marginal gain could well be my epitaph, but in this instance I'm not really expecting any kind of step change I'm simply working the tendencies game, I fancy that anything I do that lessens the temp under the tank can only be a good thing. The kind of difference I thought I might have been experiencing is like when you have an early morning ride out on a cool damp morning when the bike just feels really sweet & sharp (and the world seems a wonderful place). This just reminded me of a nostalgic memory from my reckless yooff. Early one morning out on my Triton off down the Dorking bypass the bike was running so sweetly, (something to be savoured in the age of old brit iron, splayed carbs, manual ign control etc). So I was thrashing along into an open long sweeping left hander, when I spot a Bobby who had pulled a spotty lad on a Fs1e, well there was absolutely no point in closing off, so I went sailing by at full chat. I can remember their faces, the Bobby looked like a man who had gone for the sprat and missed the mackerel (ie. Why couldn't I have just held on I could have had him instead), while the Lad was more like, I get pulled because an L plate fell off and you're just watching him! Happy Days! Oh yes it was the Triton that started my fixation with tweaking bikes, it's just my idea of fun.
Slob's mixture idea may well have a bearing. Does anyone have any thoughts on the will it actually work kind of aspect, or possibly what kind of issues may I be going to encounter? As always I've enjoyed reading all the feedback, all the best Bitza.

Bitza · 06-10-2020, 03:27 PM

Have just fitted the return-less set up, it starts and runs fine, but I've got a few little jobs to do before going for a spin. But looks hopeful. Bitza

Mr Gazza · 06-10-2020, 04:05 PM

I'm with you on the cool damp morning rides when it all comes together and she's going like a bird. I recall more misty nights on Brit irons when she just wants to go, but the 6 volt orange lights don't let you see where the hell you're going!! A Full Moon is a blessing.

I've often wondered if there is any connection with this apparent phenomenon and the use of water/alcohol injection on aero-engines? Possibly atmospheric pressure has an influence too?

So now in your return-less fuel rail, the fuel exits the rail on demand only from the injectors @ about a gallon an hour? So is the fuel actually in the rail above the warm engine for longer than in a looping system that returns more fuel into the tank than it uses?
Surely in a returning loop, the fuel tank is a fairly good heatsink and is probably radiating more heat from it's outside surface than it is receiving from below? and the injectors will be getting cooler fuel than from a static tube lying over the engine?

If you're going to go to some trouble, how about arranging a return to under the front of the tank, where the return pipe won't run back over the engine but rather into fresh air?

Sorry to p!ss on your fireworks..

I hope we don't have to write your epitaph any time soon..

Dukedesmo · 06-10-2020, 04:48 PM

As above, cold fuel will be denser and I agree that a system with a return would probably stay cooler than a return-less system plus give a more stable pressure.

Maybe some kind of intercooler for your fuel...

Bitza · 06-10-2020, 05:46 PM

Well having the fuel heat up in the fuel rail is one of the classic arguments against returnless systems, but typically in reference to the car type situation where the rail is within the enclosed engine compartment shared with a significant proportion of the exhaust system, and as often as not the fuel rails are made of some highly conductible material like copper or aluminium. Whereas in my new layout because there is only one pipe this can be wrapped forward around the front throttle body & back between the tank and the belt cover hence min engine contact, also with less pipping control valve etc and no oil cooler the air flow through to the rear cylinder should be improved. In the old return layout the return pipe inevitably ended up draped over the cylinder head. So all in all I'm feeling optimistic that the temp under the tank should be reduced, hence less heating of the tank/fuel and no increase (hopefully) of heating of the feed pipe. The proof of course will be in the ridding. Oh yes the last thing is that I've shaved off aprox 350gms nothing to most sane people but a fair amount when you've got down to making insignificant components such as a titanium push rod for the rear brake master. Bitza

350TSS · 06-10-2020, 06:04 PM

The world would be a much poorer place if blokes in sheds stopped trying to improve their bikes with whatever they thought would work. I, like you, took the trouble to machine a titanium push rod for the rear brake master cylinder and it is definitely better than the original.

Bitza · 06-10-2020, 07:15 PM

Dukedesmo you raise an interesting issue (well to me anyway) that of the stability of pressure. This is often sited as an advantage of return systems, because the control/relief valve can be located close to the injectors, and compared to the early Ducati systems my returnless set up will be inferior, however when Ducati introduced (2005) the cold-start kicker motor they located it where the old control valves had been and relocated the control valve in the tank with the pump, meaning that it is exactly the same distance from the injectors as mine. So I'm guessing that must be within the relevant tolerance. One advantage mine has though is that because the volume of pipework is halved then it should respond quicker when the pump comes on/control valve closes.

crust · 06-10-2020, 08:25 PM

Not sure about the fuel temp difference but then I'm an old school carbs person.

If under tank air temps are an issue how about something like these?

http://ukmonster.co.uk/monster/showthread.php?t=40889

Darren69 · 07-10-2020, 07:30 AM

Quote:

Originally Posted by crust

Not sure about the fuel temp difference but then I'm an old school carbs person.

If under tank air temps are an issue how about something like these?

http://ukmonster.co.uk/monster/showthread.php?t=40889

Those air runners do actually help keep the rear cylinder a bit cooler. I was skeptical until having fitted some.

No connection but there are some on ebay that should fit the early shape frames: -

https://www.ebay.co.uk/itm/Ducati-Mo...97.m4902.l9144

Dukedesmo · 07-10-2020, 10:03 AM

Quote:

Originally Posted by Bitza

Dukedesmo you raise an interesting issue (well to me anyway) that of the stability of pressure. This is often sited as an advantage of return systems, because the control/relief valve can be located close to the injectors, and compared to the early Ducati systems my returnless set up will be inferior, however when Ducati introduced (2005) the cold-start kicker motor they located it where the old control valves had been and relocated the control valve in the tank with the pump, meaning that it is exactly the same distance from the injectors as mine. So I'm guessing that must be within the relevant tolerance. One advantage mine has though is that because the volume of pipework is halved then it should respond quicker when the pump comes on/control valve closes.

The only fuel injected bike I have any experience with is the 916 and this has the regulator in the tank. I was thinking that the extra volume of fuel in the system would help with the stability by having more pressurised fuel in 'reserve'? although I admit to not knowing if this is actually the case.

I believe some cars use a 'fuel cooler' TVR being one of them but not sure how it cools - if it uses the A/C system then it might not be much use on a bike!!

http://www.powersperformance.co.uk/s...g/fuel-cooler/

spuggy · 08-10-2020, 07:29 PM

Uhmm... At least on cars, the fuel pump is designed to be both lubricated and cooled by the fuel. Without fuel return, or a relief valve, that pump is going to stay full of the same fuel, getting hotter and hotter. Surely, that's the exact opposite of what you're trying to achieve?

I've always been led to believe that you can't dead-head most modern fuel pumps (eg to use with carbs, which want a very low pressure); you still return to the tank.

I have no idea how a flow-through pressure regulator https://help.summitracing.com/app/an...UyMSUyMQ%3D%3D can work if you dead-head the return. I don't think it can...

Did you check to see what the pressure is in the fuel rail now?

Think you would want to change the pressure regulator for a "blocked" one (with no return), and you'll apparently need a pressure relief on the fuel pump. https://www.onallcylinders.com/2017/...%20carburetor.

These regulators seem to be intended for use with low-pressure systems - eg carbs, which want about 3-5 psi, so may not even be available for EFI systems (that typically want 10x that, or 3 bar) - and seem to have numerous disadvantages, such as pressure spikes, more susceptible to debris, works the pump harder for more noise/heat & shorter life, and prone to vapour-locking.

03-10-2020, 07:07 PM	#1
Bitza Bronze Member Join Date: Jul 2006 Location: Poole Bike: M900ie Posts: 470	Altering Injection Feed Layout Hi all, anyone got any comments to make about my current mod. The bike is a 94 chassis with a DS lump, currently using the throttles/injectors off a 2001 900ie with the standard period feed & return fuel line system. Now I always had a feeling that the bike ran better just after filling up with fuel, it seemed that little bit sharper. I fancied that if it wasn't simply my imagination, then it would probably be down to the new fuel being cooler and which subsequently warms up. So to lessen the opportunities for heat transfer, I've just got a low slung oil cooler and I'm going to get rid of the fuel return. Easy to do because I use a non-ducati fuel pump that comes in both return & returnless forms. So the big questions are first will it work no problem and might it also help lessen any heating effect? On the bright side I will at least shred a bit of weight and will also open up air flow a bit too. As always all comments most welcome, Bitza __________________ Bitza

03-10-2020, 07:28 PM	#2
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,806	I don't really see your logic. Surely the new fuel won't be any cooler than a half a tank that's been sitting in the bike since you last used it? I can't see the fractions of a degree difference in fuel temperature making a perceivable difference to performance. I've never noticed anything like that on my 900ie. If anything I think it would be down to the additional pressure in the new head of fuel, but then I shouldn't think it would alter the pressure in the fuel rail after going through the pump, unless your pump works in a different way to a standard one with regulator in the rail? If temperature is really what is giving the effect you perceive, then maybe an insulated fuel pipe up to the injectors and then a return via a small cooler such as is sometimes installed in oil lines of dry sump systems? I can see how the low slung oil cooler might keep warm air flow off the top of the engine and fuel rail, but I would be worrying about a stone going through it, unless of course you have a guard. Just playing devils advocate here, I actually admire your experiments and projects.. Hopefully an interesting debate will follow.. __________________

03-10-2020, 08:24 PM	#3
Nickj Too much time on my hands member Join Date: Jun 2007 Location: Forest Of Dean Bike: S2r Posts: 3,189	I suppose cold fuel would have much the same effect, though to a lesser degree, as feeding cold air to the motor. Cold fuel certainly works with diesel -> https://www.sciencedirect.com/scienc...43967115000112 I can't see why there wouldn't be the same effect with higher flammability fuels like petrol __________________ "The final measure of any rider's skill is the inverse ratio of his preferred Traveling Speed to the number of bad scars on his body." Song of the sausage creature

03-10-2020, 09:19 PM	#4
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,710	Sounds like a load of work for very marginal, if any, gain. But very happy to be proved wrong ;-) edit: If you think fuel temperature is making a difference, and cold fuel is denser than warm fuel, could it be that the bike is running a little lean at ambient temp? Possibly due to a better breathing air filter. What do the plugs look like? Last edited by slob; 03-10-2020 at 10:05 PM.. Reason: just a thought

04-10-2020, 09:08 AM	#5
Bitza Bronze Member Join Date: Jul 2006 Location: Poole Bike: M900ie Posts: 470	A load of effort for marginal gain could well be my epitaph, but in this instance I'm not really expecting any kind of step change I'm simply working the tendencies game, I fancy that anything I do that lessens the temp under the tank can only be a good thing. The kind of difference I thought I might have been experiencing is like when you have an early morning ride out on a cool damp morning when the bike just feels really sweet & sharp (and the world seems a wonderful place). This just reminded me of a nostalgic memory from my reckless yooff. Early one morning out on my Triton off down the Dorking bypass the bike was running so sweetly, (something to be savoured in the age of old brit iron, splayed carbs, manual ign control etc). So I was thrashing along into an open long sweeping left hander, when I spot a Bobby who had pulled a spotty lad on a Fs1e, well there was absolutely no point in closing off, so I went sailing by at full chat. I can remember their faces, the Bobby looked like a man who had gone for the sprat and missed the mackerel (ie. Why couldn't I have just held on I could have had him instead), while the Lad was more like, I get pulled because an L plate fell off and you're just watching him! Happy Days! Oh yes it was the Triton that started my fixation with tweaking bikes, it's just my idea of fun. Slob's mixture idea may well have a bearing. Does anyone have any thoughts on the will it actually work kind of aspect, or possibly what kind of issues may I be going to encounter? As always I've enjoyed reading all the feedback, all the best Bitza. __________________ Bitza Last edited by Bitza; 06-10-2020 at 03:24 PM..

06-10-2020, 03:27 PM	#6
Bitza Bronze Member Join Date: Jul 2006 Location: Poole Bike: M900ie Posts: 470	Have just fitted the return-less set up, it starts and runs fine, but I've got a few little jobs to do before going for a spin. But looks hopeful. Bitza __________________ Bitza

06-10-2020, 04:05 PM	#7
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,806	I'm with you on the cool damp morning rides when it all comes together and she's going like a bird. I recall more misty nights on Brit irons when she just wants to go, but the 6 volt orange lights don't let you see where the hell you're going!! A Full Moon is a blessing. I've often wondered if there is any connection with this apparent phenomenon and the use of water/alcohol injection on aero-engines? Possibly atmospheric pressure has an influence too? So now in your return-less fuel rail, the fuel exits the rail on demand only from the injectors @ about a gallon an hour? So is the fuel actually in the rail above the warm engine for longer than in a looping system that returns more fuel into the tank than it uses? Surely in a returning loop, the fuel tank is a fairly good heatsink and is probably radiating more heat from it's outside surface than it is receiving from below? and the injectors will be getting cooler fuel than from a static tube lying over the engine? If you're going to go to some trouble, how about arranging a return to under the front of the tank, where the return pipe won't run back over the engine but rather into fresh air? Sorry to p!ss on your fireworks.. I hope we don't have to write your epitaph any time soon.. __________________

06-10-2020, 04:48 PM	#8
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,842	As above, cold fuel will be denser and I agree that a system with a return would probably stay cooler than a return-less system plus give a more stable pressure. Maybe some kind of intercooler for your fuel... __________________ M900, 916, LeMans II.

06-10-2020, 05:46 PM	#9
Bitza Bronze Member Join Date: Jul 2006 Location: Poole Bike: M900ie Posts: 470	Well having the fuel heat up in the fuel rail is one of the classic arguments against returnless systems, but typically in reference to the car type situation where the rail is within the enclosed engine compartment shared with a significant proportion of the exhaust system, and as often as not the fuel rails are made of some highly conductible material like copper or aluminium. Whereas in my new layout because there is only one pipe this can be wrapped forward around the front throttle body & back between the tank and the belt cover hence min engine contact, also with less pipping control valve etc and no oil cooler the air flow through to the rear cylinder should be improved. In the old return layout the return pipe inevitably ended up draped over the cylinder head. So all in all I'm feeling optimistic that the temp under the tank should be reduced, hence less heating of the tank/fuel and no increase (hopefully) of heating of the feed pipe. The proof of course will be in the ridding. Oh yes the last thing is that I've shaved off aprox 350gms nothing to most sane people but a fair amount when you've got down to making insignificant components such as a titanium push rod for the rear brake master. Bitza __________________ Bitza

06-10-2020, 06:04 PM	#10
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	The world would be a much poorer place if blokes in sheds stopped trying to improve their bikes with whatever they thought would work. I, like you, took the trouble to machine a titanium push rod for the rear brake master cylinder and it is definitely better than the original.

06-10-2020, 07:15 PM	#11
Bitza Bronze Member Join Date: Jul 2006 Location: Poole Bike: M900ie Posts: 470	Dukedesmo you raise an interesting issue (well to me anyway) that of the stability of pressure. This is often sited as an advantage of return systems, because the control/relief valve can be located close to the injectors, and compared to the early Ducati systems my returnless set up will be inferior, however when Ducati introduced (2005) the cold-start kicker motor they located it where the old control valves had been and relocated the control valve in the tank with the pump, meaning that it is exactly the same distance from the injectors as mine. So I'm guessing that must be within the relevant tolerance. One advantage mine has though is that because the volume of pipework is halved then it should respond quicker when the pump comes on/control valve closes. __________________ Bitza

06-10-2020, 08:25 PM	#12
crust rattles when he walks Join Date: Aug 2002 Location: in the comfy chair,moved furniture around Bike: M900 Posts: 1,065	Not sure about the fuel temp difference but then I'm an old school carbs person. If under tank air temps are an issue how about something like these? http://ukmonster.co.uk/monster/showthread.php?t=40889

08-10-2020, 07:29 PM	#15
spuggy Registered User Join Date: Apr 2016 Location: Farnborough Bike: M900sie Posts: 171	Uhmm... At least on cars, the fuel pump is designed to be both lubricated and cooled by the fuel. Without fuel return, or a relief valve, that pump is going to stay full of the same fuel, getting hotter and hotter. Surely, that's the exact opposite of what you're trying to achieve? I've always been led to believe that you can't dead-head most modern fuel pumps (eg to use with carbs, which want a very low pressure); you still return to the tank. I have no idea how a flow-through pressure regulator https://help.summitracing.com/app/an...UyMSUyMQ%3D%3D can work if you dead-head the return. I don't think it can... Did you check to see what the pressure is in the fuel rail now? Think you would want to change the pressure regulator for a "blocked" one (with no return), and you'll apparently need a pressure relief on the fuel pump. https://www.onallcylinders.com/2017/...%20carburetor. These regulators seem to be intended for use with low-pressure systems - eg carbs, which want about 3-5 psi, so may not even be available for EFI systems (that typically want 10x that, or 3 bar) - and seem to have numerous disadvantages, such as pressure spikes, more susceptible to debris, works the pump harder for more noise/heat & shorter life, and prone to vapour-locking.