Road going ITB setup

[Tommy]

Just couple of thougths for your experimenting...maybe this goes without saying but it is relevant to the pooling issues.

Be prepared, if you get backfire and see flames, floor it and the flames will be sucked in the engine. In case it doesn't work, have a good size fire extinguisher on hand.

[tzei]

23 minutes ago, NickVyse said:

A Hardi pump would solve that

Sorry but isn't this for carb(s). I don't think it will produce 3.0 bar(ish) that EFI needs.

[popovm]

On 3/18/2023 at 3:36 PM, Dudeland said:

I also get a small amount of puddling with my TBI sniper system,  largely due to the hard left-hand turn it takes in the manifold.  At idle, my 2L doesn't shift enough air for the size of TB (about 51mm X2) I have.   Once I am off idle, it clears its throat and dries out quickly.  Just before I put it away for the winter (2 years ago), I took a lot of fuel out of the idle, and it fundamentally solved it. 

sorry to highjack but what parts are you running in your sniper setup? Have a thread or blog post on this? When I looked around didn’t see any Holley Sniper (or from any manufacturer for that matter) TBI stuff that looked small enough for a 4 cylinder. 

[jimk]

7 hours ago, NickVyse said:

 

A Hardi pump would solve that - it only pumps when required and maintains a steady pressure.

 

Kraftstoffpumpe 18812 (12V / ab 100PS) - HARDI Automotive

WWW.HARDI-AUTOMOTIVE.COM

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HARDI Kraftstoffpumpe 18812 für den größeren Druckbereich 0,28-0,35 bar. Förderleistung 100-130 Liter/h. Betriebsspannung 12 Volt.

 

EFI systems don't work well with floating fuel pressure which the pump will have (pressure hysteresis)  The SDS system doesn't have capability to input a flow table based on injector differential pressure and most injectors are not even supplied with the data.

[Dudeland]

14 hours ago, popovm said:

sorry to highjack but what parts are you running in your sniper setup? Have a thread or blog post on this? When I looked around didn’t see any Holley Sniper (or from any manufacturer for that matter) TBI stuff that looked small enough for a 4 cylinder. 

I use the sniper 2bbl setup. And you are right.  It is Juuuusssttttt a little too big. It is tricky to get it set up.  I finally cracked the code just before I parked it. 

 

The stock single barrel would be perfect with this one below.  A single 36mm barrel.   Supports up to 175HP.  

 

Holley Sniper EFI 550-552 Holley Sniper EFI Autolite 1100 - Gold

WWW.HOLLEY.COM

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Are you tired of struggling with the old Autolite model 1100 series carburetor on your classic Ford? Does your street cruiser currently hesitate at extreme temperatures? The team at Holley has designed the perfect solution for your problems. The Sniper EFI replacement throttle...

 

This one looks better.  It is 2x 32mm barrels.  I would love to try this one. Mine has 2x51mm and the idle is difficult (not impossible) to set. 

 

Holley Sniper EFI 550-859K Holley Sniper EFI BBD Master Kit for Jeep CJ - Black

WWW.HOLLEY.COM

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Introducing the Sniper EFI BBD Master Kit, for Jeep CJ's! The BBD specific system will be right at home on any 258ci powered trail rig, or weekend cruiser. Not only does this TBI conversion offer superior throttle response and WOT power over the carburetor, but you can also gain...

 

De-hijacking now. 

 

 

 

[squirt46]

Tried doing an update two weeks back but couldn't add to this thread.  So, here we go again!

We're using the original 2002 fuel line for return to the gas tank from the pressure regulator/manifold, and it was plugged up with fine rust. 

Jeff cleaned up the wiring and got it routed properly, but we were re still struggling with the pressures.  He disconnected the return line from the downstream of the pressure regulator and got about 37 psi at the manifold.  This past Friday, we disconnected the return line again at the manifold and ran air from the compressor into the line.  Most of the air didn't get into the line, but I thought I heard bubbling out of the fuel tank.  We disconnected at the fuel tank and blew air in from the manifold end and got a bunch of fine grit deposited onto the cloth we were holding over the end.  Blew air both ways until most of it was actually going into the line, hooked up the manifold again and ran a couple of litres of gasoline down the line and into a jug - fair bit of crud came through.  Hooked it all up again and - YAY! - the engine started!  And we got a steady 37 psi at the manifold.  Jeff leaned it down at idle and the puddling isn't as bad, but it needed more enriching to allow it to rev up.  Looking into the throat of the DCOE and watching the wee droplets reminded me of spilled mercury droplets, consolidating.

I recalculated what fuel quantity would be required (assuming 118 hp  and 140 hp, based on the ratings for the Ti and Tii in the 70s) and came up with 18 to 22 lb/hr.  The injectors we're using move 31.4 lb/hr at 43.5 psi; however, at 12 psi they'll move 16.5, and 17.8 at 14 psi.  I'm thinking that I screwed up on the injection pressures, as we're using a throttle body injection system which (per my brother, a retired auto mechanic) should be at 9 to 13 psi.  This is the range that the throttle body injection systems used in the 80s/90s in North American cars, and Patton Machine recommends 14 to 16 psi for their TBI conversion kits for SU carbs.

Jeff pointed out that the SDS injector bosses appear to be designed to be welded onto thinner wall tubing than the cast wall thickness of the DCOEs, so our injector are pushed a little bit further out from the air stream than might be ideal.  He'll bring over a carbide bit next time and we'll pull the carbs and open up the opening where the injectors are firing into the throttle bores, as we're maybe/probably having the spray from the injectors hitting the edges of the hole drilled into the DCOE.  Touch wood, this will help with the puddling.

The step after that will be to get an adjustable pressure regulator that can take the 80 psi (or whatever the BMW pump in the gas tank is producing) down to that 12 - 16 psi range.  And I'm not having a lot of success in finding one, but still looking.

Progress is being made, and fingers continue to be crossed.  I need a t-shirt that announces 'Prototyping is a bugbear'.

[jimk]

Fuel puddling was predicted.

Your calculation for a WOT fuel flow rate seems low unless you mean per cylinder.  Sizing program attached.

The throttle body injections system of earlier times had injectors designed for low fuel pressure.  Operating 3 bar injectors at such a low pressure won't provide very good fuel atomization.  What is the downside at operating the system at 3 bar?

A cruddy return line will plague you for a long time.  Particles will sluff off at various times.

 

MSD Injector Sizing.zip

Edited April 4, 2023 by jimk

[squirt46]

jimk:  is there a way of changing the fuel pressure in the MSD Injector Sizing calculator?  Looks like it's set at  43.5 psi.  We're using a Throttle Body Injector layout, with the injectors upstream of the butterflies, and my understanding is that that system requires a lower pressure.  And my 18 to 22 lb/hr is for each injector.  Thanks for the file.  DOug

[jimk]

The fuel requirements for a power output is the same no matter what the fuel rail pressure is.

The injector rated flow varies the ratio of the square root of the ratio of pressures (if I remember fluid mechanics correctly). So if the pressure ratio is 14/43 then the flow rating would be (14/43.5)^0.5 = 0,56 or 56% of the 3 bar rating.

 

Keep in mind the rated injector flow is at 100% duty cycle.

 

Anybody - If I'm brain dead, please correct me.

[Tommy]

6 hours ago, squirt46 said:

jimk:  is there a way of changing the fuel pressure in the MSD Injector Sizing calculator?  Looks like it's set at  43.5 psi.  We're using a Throttle Body Injector layout, with the injectors upstream of the butterflies, and my understanding is that that system requires a lower pressure.  And my 18 to 22 lb/hr is for each injector.  Thanks for the file.  DOug

I don't get why you would want different pressure for the (same) injector depending on the placement. If you have 3bar (or 43,5psi) injectors the pressure should be in that range for them to work well. Maybe your conception is from some old TBI system that had injector(s) specced for lower pressure? 

[uai]

2 hours ago, Tommy said:

I don't get why you would want different pressure for the (same) injector depending on the placement. If you have 3bar (or 43,5psi) injectors the pressure should be in that range for them to work well. Maybe your conception is from some old TBI system that had injector(s) specced for lower pressure? 

perhaps: 
If you have your injector at athmospheric pressure you want to have e.g. 3 bar fuel pressure (compared to athmospheric)
but if you have your injector in the manifold right befor the valve you want to have 3 bar fuel pressure compared to manifold pressure - so less than 3 (4 if you include athmospheric) bar absolute pressure 
 

Edited April 5, 2023 by uai

[jimk]

3 hours ago, uai said:

but if you have your injector in the manifold right befor the valve you want to have 3 bar fuel pressure compared to manifold pressure - so less than 3 (4 if you include athmospheric) bar absolute pressure 

You are correct, but it all works out in the tuning that compensates for all the inaccuracies in the setup.

 

The ECU that I have has a table for injector flow compensation for the differential pressure across the injector.

 

There are other means to compensate like with a manifold pressure compensated fuel pressure regulator. The manifold pressure ranges from approx 30 kPa to near 100 kPa depending on engine load.

Edited April 5, 2023 by jimk

[squirt46]

I purchased a FASS     FSY-FPR-1001    adjustable (0 - 100 psi) fuel pressure regulator and it arrived today.  I'd hoped to pick up the fittings we'd need to match it to the fuel manifold (facing word for a sold block of aluminum with various holes etc. in it) locally, but it's a bit like Lego:  needed some pieces we couldn't get.  Dang!  The manifold has a smooth walled/bolt down port for a simple (Subaru? fixed pressure regulator):  Jeff has taken that home and will hone it out and tap if for 3/8" NPS and bush the 1/2" port on the FASS regulator down so we can stick a fitting in and connect the two components.  He'll have to replace the exisitng bracket with one that will support the manifold and the regulator, and still bolt up to the inner fender.  He'll also have to hog out a good portion of the battery support to clear the new regulator, but all of that will be hidden by our  empty battery case.  Touch wood, we'll get the plumbing successfully installed next Friday (Jeff also took the DCOE bodies home and will open up the entry of the injector boss bores into the throttle bores).  We know it'll start and - once installed and running - then we'll start lowering the injector pressure and monitoring the richness/leanness at idle along with the 'puddlng' issue.  We had puddling at 37 psi; figure we'll keep monitoring and drop the fuel pressure until the puddling goes away.  If it's above, let's say, 14 psi, then continue to drop the the pressure until we're down to the 12-14 psi range.  Then try to optimize for idle, and see how things look at wider throttle openings.  Fingers crossed, all the way.

[squirt46]

Well, dang.  Jeff got everything installed (Weber DCOE bodies with the injector hole into the throttle bore opened up; the FASS adjustable fuel pressure regulator installed, etc.).  The car started after a bit of trying, but we've still got puddling (even down at 16 psi)   So, a couple of steps forward; a couple of steps back.  We don't have the radiator installed, so no engine temperature signal.  Try that next;  Also try lowering the passenger side of the vehicle such that the gs puddling in the throttle bores will run into the manifold and the combustion chamber, and we'll get a more accurate/representative signal off the exhaust header sensor.  Wondering if there's some way of getting the injector face closer into the throttle bores as well.  I was hoping that being able to adjust the fuel pressure would resolve the puddling issue, but no such luck.  Now I'm wondering if the injectors don't work consistently at the low pressures.  Rather disappointed, and am running out of ideas.

[tzei]

So how far the injectors are in bores? And what angle?