28 replies to this topic

[NTSOS]

Imagine if you will, a fuel rail with injectors that moves vertically one to two inches every time full throttle is applied.....it obviously has to return when the throttle is released and the assembly also moves variably during part throttle transitions. The FI assembly is mounted within a plenum chamber and the fuel rail needs to access a fuel line mounted outside of the plenum chamber. Any ideas on a nifty joint/coupling concept that could safely accomplish this without inducing fatigue/stress related failure due to repeated applications of fuel line/fuel rail movement within the one to two inch vertical operating envelope?

Thanks!

John

[saudoso]

I lack the english terminology, but a design similar to an hidraulic actuator or a plunger? The rail would slide around the fuel line tip. Just consider the making fuel feeding sideways with the line ending shut, to avoid the rail being pushed by the fuel pressure.

[saudoso]

Like this:

[NTSOS]

Like this:

Oh, yes......that would be perfect.......let me see what I can find!

Thanks man!

John

[NTSOS]

Like this:

Yes sir saudoso....after thinking about your drawing, I can easily machine a fuel rail slide assemby block using linear bearings and glass filled dynamic seals with a hollow/hardened SS fuel supply rod.

Thanks again for the idea!

Juanito

[saudoso]

Would be cool if it works. Keep us posted!

You are blending throtle with the injectors? Like the injector assembly opens/closes the intake trumpet mouth?

Edited by saudoso, 26 April 2013 - 20:31.

[NTSOS]

Would be cool if it works. Keep us posted!

You are blending throtle with the injectors? Like the injector assembly opens/closes the intake trumpet mouth?

Yes sir, it's kind of like that but in this case it would not be the primary engine throttle, but a variable device controlled by an air cylinder off of manifold pressure......but I don't see why a foot operated primary throttle such as you describe would not work in a normally aspirated engine.......very interesting!

Thanks!

John

[Greg Locock]

Yes sir, it's kind of like that but in this case it would not be the primary engine throttle, but a variable device controlled by an air cylinder off of manifold pressure......but I don't see why a foot operated primary throttle such as you describe would not work in a normally aspirated engine.......very interesting!

Thanks!

John

That's elegant, but the obvious way to my mind is a flexible hose and a banjo bolt. Your fuel lines already have an equivalent arrangement to allow the engine to roll.

[saudoso]

If I got it right NTSOS' concern is after the high pressure pump into the rail.

Edited by saudoso, 26 April 2013 - 23:15.

[Lee Nicolle]

Lost me. Why move the fuel rail? Unless ofcourse it moves with the ram tubes. Most injectors on race engines are near the ram tube mouth these days. Only one I have seen upclose had flexible lines from the rail to injector.

[Tony Matthews]

The Ilmor 265E/500I had two bosses cast on the inlet manifolds, one low, one high, in case secondary injectors were needed further up the airstream. In the event they weren't needed.

[NTSOS]

That's elegant, but the obvious way to my mind is a flexible hose and a banjo bolt. Your fuel lines already have an equivalent arrangement to allow the engine to roll.

Yes Greg, that would definitely be the easiest method. Problem is, there is not much space in the plenum area where the fuel rail is located and it would require a very tight loop to allow the fuel line to wind and unwind as the rail repeatedly rises and falls along with the mechanism.......and I was concerned about fatigue failure. I think it would work just fine if it was the length of a flexible brake line on a IFS, but in this application it is very short and tight......I don't know, it's just a gut feel.....what do you think?

Thanks!

John

[NTSOS]

Lost me. Why move the fuel rail? Unless ofcourse it moves with the ram tubes. Most injectors on race engines are near the ram tube mouth these days. Only one I have seen upclose had flexible lines from the rail to injector.

It's an updated variable geometry mechanism that I've used since the '80's Lee, and on the new design, the fuel rail and injectors are kind of along for the ride! If I had access to DI, that would certainly circumvent all the monkeying around with the rail and injectors!

Thanks!

John

[NTSOS]

I guess to get good torque and top end power at the same time, depending of the rpm/load condition.
In the past, some people have used a near and a far injector per trumpet and switched from near for low rpm
to far at a higher rpm in some Supertouring car engines the cross over point was at ~5500 rpm (8500 rpm max.).

Saudoso's proposal is neat, if you have the extra vertical space in the plenum/airbox to spare, which depending on
the application, could be a challenge.

dual injector layout:

Yes, saudoso's proposal is neat and there actually is vertical space "outside" of the plenum for the fuel delivery tube to operate. It is a strictly street turbo supercharged application and there is virtually no intake port beyond the cylinder head, so there is little room for injector placement....hence, they are along for the ride with the movement of the variable mechanism......like I said, access to an aftermarket DI system would eliminate the hassle, but that's probably not going to happen for awhile. In any case and as the result of necessity, it would be interesting to note the effect on power production at various injector heights above the inlet port at differing RPM's

Thanks!

John

[NTSOS]

The Ilmor 265E/500I had two bosses cast on the inlet manifolds, one low, one high, in case secondary injectors were needed further up the airstream. In the event they weren't needed.

Tony, do you recall if they ever used two injectors per cylinder?

Thanks!

Juanito

[kikiturbo2]

gsxr 1000 engine from K5 onward has twin injectors per cylinder.. one is positioned upstream, and they also have different angles..

[Tony Matthews]

Tony, do you recall if they ever used two injectors per cylinder?

Thanks!

Juanito

They may have tested with them, John, but they were never used in anger as far as I know, they just remained as unused, unmachined bosses on the castings. Wouldn't be the first occasion of a useless boss!



Edited to add that there were two injectors per trumpet, firing down from inside the plenum.

Edited by Tony Matthews, 27 April 2013 - 18:19.

[NTSOS]

They may have tested with them, John, but they were never used in anger as far as I know, they just remained as unused, unmachined bosses on the castings. Wouldn't be the first occasion of a useless boss!



Edited to add that there were two injectors per trumpet, firing down from inside the plenum.

Yes sir, that was exactly the same conclusion that Ricardo had......he gave up trying to figure out where to cast bosses for sensors/probes etc. and simply increased the wall thickness of all castings on the test engines!

Thanks!

Juan

[Magoo]

One reason to have 2x injectors on champ car engine is methanol, which requires big fuel mass delivery. Doubling up allowed inexpensive production-based injector rather than some hideously expensive handmade thing.

[Greg Locock]

One reason to have 2x injectors on champ car engine is methanol, which requires big fuel mass delivery. Doubling up allowed inexpensive production-based injector rather than some hideously expensive handmade thing.

Esprit Turbo had two extra injectors, at the time you couldn't get injectors which gave enough max fuel rate and good idle control. Or perhaps it was cheaper!

[kikiturbo2]

also, sierra cosworth rs 500 had two sets of injectors for homologation purposes... one set did not work on stock cars..

as for injector size.. with the growing popularity of E85, 1200 to 2000 cc injectors are becoming quite common..

[Canuck]

Yes Greg, that would definitely be the easiest method. Problem is, there is not much space in the plenum area where the fuel rail is located and it would require a very tight loop to allow the fuel line to wind and unwind as the rail repeatedly rises and falls along with the mechanism.......and I was concerned about fatigue failure. I think it would work just fine if it was the length of a flexible brake line on a IFS, but in this application it is very short and tight......I don't know, it's just a gut feel.....what do you think?

Thanks!

John

I'll see if I can't sketch it out later to explain what I mean. If I'm in the plenum looking towards the rear, injector bank on either side with their respective fuel rails. End of each rail has a straight banjo fitting (meaning it protrudes perpendicular to the rail towards the center of the plenum). The flexible fuel line runs across the centre of the plenum towards the opposite side where it's mating banjo fitting is located - as far as practicable along the rear wall of the plenum, on the opposite side. This gives the maximum distance between fittings to allow for "excess" line.

Along the same lines, one could use a 90' fitting at the back of the rail, a bulkhead fitting on the same side and run the loop from the rear of the plenum to the banjo located on the front. Or even loop it back again so the flexible line runs back to front to back again. All kinds of space for loop length.

In terms of fatigue - motorcycle front forks and rear swingarms require flexible brake lines. Forks move in a purely linear fashion constantly with several inches of travel and brake line mechanical fatigue is never a concern despite being exposed to all the debris on the road, the constant flexing and the very high line pressures.

All that said, I'm envisioning motorcycle steel braided brake lines which are considerably smaller than a fuel line would need to be. Should still work scaled up depending on the space constraints.

[NTSOS]

I'll see if I can't sketch it out later to explain what I mean. If I'm in the plenum looking towards the rear, injector bank on either side with their respective fuel rails. End of each rail has a straight banjo fitting (meaning it protrudes perpendicular to the rail towards the center of the plenum). The flexible fuel line runs across the centre of the plenum towards the opposite side where it's mating banjo fitting is located - as far as practicable along the rear wall of the plenum, on the opposite side. This gives the maximum distance between fittings to allow for "excess" line.

Along the same lines, one could use a 90' fitting at the back of the rail, a bulkhead fitting on the same side and run the loop from the rear of the plenum to the banjo located on the front. Or even loop it back again so the flexible line runs back to front to back again. All kinds of space for loop length.

In terms of fatigue - motorcycle front forks and rear swingarms require flexible brake lines. Forks move in a purely linear fashion constantly with several inches of travel and brake line mechanical fatigue is never a concern despite being exposed to all the debris on the road, the constant flexing and the very high line pressures.

All that said, I'm envisioning motorcycle steel braided brake lines which are considerably smaller than a fuel line would need to be. Should still work scaled up depending on the space constraints.

Yes sir, got it.......all great ideas as it relates to flexible fuel line configurations/management within a plenum.......I came to the right place!

Thanks man!

Additionally, a nice little street engine on the dyno....I love to start and stop the video and watch the dials on the last pull!

a street engine!

John

PS.....I wish Tom would say lb/ft!

[Magoo]

a street engine!

John

PS.....I wish Tom would say lb/ft!

Just goes to show that talking the talk isn't everything. Love the stock FEAD, A/C compressor, etc. Just a stock little motor. Less than 2 bar MAP, that's nothing.

[NTSOS]

Just goes to show that talking the talk isn't everything. Love the stock FEAD, A/C compressor, etc. Just a stock little motor. Less than 2 bar MAP, that's nothing.

True......and I agree, have always preferred the stock FEAD to the after market billet stuff! The original Electromotive FI unit is what got me started working with computers. I bought an 8086 computer with a floppy drive and it had a turbo button that scared me. It changed the processor speed from 4 MHz to an incredible 8 MHz.......but I didn't push it for over a year because I wasn't sure what it was for!

[saudoso]

Did this fly?

[NTSOS]

Did this fly?

Yes sir.......combined your fuel supply tube idea, the injector and the air cylinder piston rod that controls the variable geometry into a single rod/multi purpose assembly. The more I think about, the more integrated it becomes so I am in no hurry to build it just yet.

Thanks!

John

[saudoso]

Please keep us posted!

[indigoid]

Esprit Turbo had two extra injectors, at the time you couldn't get injectors which gave enough max fuel rate and good idle control. Or perhaps it was cheaper!

presumably these injectors have a lower bound on the time taken to open/squirt/close, so it could make some sense to have smaller injectors for when you don't need a firehose per cylinder