I did some low boost testing to compare differential fuel flow at 1bar between the old bosch 044 and new Walbro 450.

Bosch 044 - This run started off base fuel pressure with the bosch 044 at 50psi dropping to 46.8psi on the top of 3rd stabilizing to 47psi for the rest of 4th gear. 100-200 was completed in 7.81s,
https://fdoc.co.uk/forum/attachments...721-png.39016/

The walbro 450 started the run with 50psi and shows a similar differential fuel pressure drop. Its not the end of the world as there could be some parasitic loss but i was hoping the walbro being more modern and powerful pump could have pushed through it and held a stable 50psi diff fp. The 100-200 was completed in 7.62 so no performance loss and within 0.2s of the previous pump at this level on a very safe and conservative tune.

https://fdoc.co.uk/forum/attachments...982-png.39017/

On paper the walbro 450 is meant to flow more at 50psi base + 15.5 boost = approx 65psi. An approx 23% increase in fuel flow....yet in reality the logs confirm its no better than the older 044. It's truly very strange, perhaps a single walbro 450 is not better than the old school 044.

https://fdoc.co.uk/forum/attachments...708-png.39018/

Careful with this bulkhead connector.
When you run bigger pumps that connector will melt and short out.
The stock FD wiring cannot support the draw from bigger pumps.
I changed mine out to a ATL bulkhead and fuel safe wiring.


https://cimg4.ibsrv.net/gimg/www.rx7...8d8e710db.jpeg


Steve

The Bosch Motorsports '044 pump flow rating from Bosch is done with a more viscous than gasoline fluid, so its flow is under-rated by the factory.

If you meant '044 flowing more than independent comparison testing on gasoline then IDK whats up.

Hey thanks for the heads up, will have to do the same thing eventually.

I got the Bosch 044 flow data from https://www.realstreetperformance.co...mance/#results
which was posted previously on the thread.

That is data for the AEM knock-off of the Bosch '044 pump.

Back when Bosch still made genuine '044 I saw data from comparisons where the real '044s outflowed the knock-offs at high pressures.

Bosch now sells the higher flowing (0-580-464-200) fuel pump to replace the '044 (0 580 254 044)

You definitely need wiring to support higher demand, it will turn the pump harder with higher actual voltage at the pump. More injector and lower base pressure will net more total flow from the same pump too.

Ahh that would be the most sensible conclusion as the low boost data suggests the bosch 044 seems to flow similar to the walbro 450. Strange that knock offs would be used in a fuel flow test. I may try one high boost hit and see if the differential fuel pressure does the same as the bosch or holds more stable. Looking at the low boost data it doesnt look promising.

That's def a good shout.

Currently, I'm running AN6 lines throughout. I've integrated two inline filters, which I plan to disassemble and clean to assess any impact.

One consideration is the lack of 10 AWG wiring within the submersible section of the fuel hanger causing a voltage drop. Although I've ensured 10 AWG wiring from the battery to the fuel hanger, there's a possibility that the internal electrical connector might not handle the full electrical load as mentioned by Steve in the previous post. I've ordered the bulkhead to ensure 10awg wire goes into the submersible part of the pump to address this issue.

Another potential factor is the accuracy of the fuel flow data I acquired for the Bosch 044 fuel pump from the above link and as stated by blue tii.

Did a comparison test on high boost approx 24psi between the bosch 044 and walbro 450.

Bosch 044
Differential fp - 50psi
Drops to 35psi and holds.
https://fdoc.co.uk/forum/attachments...run-jpg.39019/


Walbro 450
Differential fp - 50psi
Drops to 44psi but clearly the winner of the two pumps at 24.5psi.
https://fdoc.co.uk/forum/attachments...-57-jpg.39020/

However, both pumps still display weird oscillations. Not entirely sure what that is.

That looks like hydraulic resonance. (FPDs are intended to damp this phenomenon.)

Lots of hard line and no pulse damper?

here's a sample of my diff fuel pressure. variance about 2 tenths of a pound, logged around 30 hz. one 285 pump. 33% E. in a later dyno at 77% E my diff FP dropped to 19. i have since added another (274) pump and a 320 amp alternator as voltage had dropped to 13.9. this is w the Radium sump setup and a 267 lift pump. agree w Speed of Light and Slides as to the "why".


https://imagizer.imageshack.com/v2/1...924/rfLWRq.png

Thanks guys, running the standard oem damper from the primary line, clearly not good enough.
Nice one Howard, that looks way better. Which turbo are you running on this setup?
I upgraded to the link g4x today and ive run into some teething issues with the ecu transfer, the fuel and oil pressure calibrations dont seem to be playing ball with the g4x and the live logging parameters seem to not record anything.
Also got some interesting data about fuel injection timing confirmed by Adam at link for the link ecu platforms.

That much oscillation would show in your lambda curve (And it seemingly does not). I would be more suspicious of the wiring of the sensor rather than a "pulsation" issue.

there's a thread here somewhere that goes into detail about large injectors and fuel pulsation.... the short version is a good FPD is recommended

I would be curious to see what a fuel pump relay would do if anything. Agree with other statements that the stock wiring is inadequate. Since your battery is next to the fuel pump, maybe try a relay to see if it changes anything.

https://www.sakebombgarage.com/plug-...ess-fd3s-rx-7/

This does not fix the stock bulkhead issue, but will make sure that your pumps are in fact getting the correct voltage. Wondering is the similar performance in the 044 and 450 is simply due to the aging wiring.

Completely forgot about this! I bought this back in September 2023 and just stumbled upon it in storage. It was time to dig it out and finally get it loaded in the car.
https://fdoc.co.uk/forum/attachments...639-jpg.39053/

The Old Faithful Link G4+ (EPIC ECU) boxed up in its new oem case ready to be shipped out to its new owner. It's an epic modern ECU that got me knocking on the door of 5-second 100-200 times. It would push even harder if my fuel system wasn't holding it back.

https://fdoc.co.uk/forum/attachments...151-jpg.39054/

Alright, all you garage queens and wiring wizards with a touch of the OCD, look away! I'm still rocking the stock ECU harness on this bad boy with all the battle scars. It's 32 years old, a tangled mess of wires held together by hope and zip ties, but damn it gets the job done. This thing pulled me into the 5-second club for the 100-200 and fires up every time I grab the keys and unleash the fury of the FD. Don't need fancy, new-age stuff when the old relic does the trick!

https://fdoc.co.uk/forum/attachments...528-jpg.39055/

Hold my beer! Just shoved a brand new Link G4X ECU into the crusty old case of my 32-year-old OEM ECU. It may look like a junkyard find, but inside it's rocking the latest tech. Talk about sleeper engine management, nothing to see here Mr Officer, its just a stock ECU.

https://fdoc.co.uk/forum/attachments...637-jpg.39056/

I got most of the sensors dialed in nice and easy. But for the love of all things boost, the oil and fuel pressure sensors were being total gremlins. Calibrated them a million times, checked every setting, but no dice. Decided to take a closer look, and wouldn't you know it, the culprit showed its face right away. Turns out a signal wire must have gotten pinched or something during the swap, because it popped right out of its crimp. At least its a simple fix.

https://fdoc.co.uk/forum/attachments...508-jpg.39058/
Here's the battle plan to crank up to 2bar ~29psi on pump fuel and wmi.

1. Gotta fix that busted G4X expansion loom. Contacted a local motorsport wiring shop and hoping they can whip up a new one. No dodgy wires holding me back this time and hopefully clean up the data from the sensors.
2. Order a radium 4-port secondary fuel rail to throw in 2 additional 1500cc injectors. Should slash my injector duty cycle from a scary 95% down to a much safer 70%, giving me the headroom I need.
3. Ditching the tired fuel pump wiring - it's time for a modern upgrade. Hoping the local motorsport wiring shop can fit me in sooner rather than later.
4. Once everything's dialed in, time to crank it up to 2 bar and see how it blasts through the 100-200. That's the real test!

But that's not all folks, got two more mods waiting in the wings to see if 2 bar can do even better.

These are the final boss mods (if you know, you know). Soon it will be time to see if the below mods can do better than the stock upper intake manifold and the old-school HKS cast iron manifold? Are they all hype (dyno queens) with no bark? or all the hype with the 100-200 to back it up? I dont know but will find out... if all goes well. Pray for me!
https://fdoc.co.uk/forum/attachments...ram-jpg.39061/

Who made the turbo manifold for you?

Sas Autoworks, fabricator from the UK. The only downside is he holds no stock and orders can take a while to complete. I had to wait about 5 months from order date to manifold being delivered.

Gentlemen and Ladies (if there are any), looking for some advise around fuel injector cc to be able to run sub 70% pri and sec duty cycle (long story head honcho at link advised to keep max dc below 70% at all times to optimise fuel injection timing, i dont understand the ins and outs of it all as most of what he said has gone over my head but will follow the advise to get dc below 70%) ...ideally with pump fuel but also future proof to have head room to run e30-e85 fuel.

I'm not great at this but want to know the correct cc to support 700hp at a max of 70% dc for the below.
1. pump fuel cc
2. e85 cc.

Current cc of flow
2x 850cc - primaries
2x 1500cc - secondaries

at 5bar (per asnu data)
850cc flow around 1200cc each
1500cc flow around 2000cc each

Total cc fuel flow = 6400cc. Duty cycle with the new walbro 450 fuel pump holding a stable base fp is around 95% around peak areas.

Planning to run
2x 850cc as primaries
4x 1500cc secondaries

at 5bar and above Asnu data suggests the below flow rate.
850cc flow around 1200cc
1500cc flows around 2000cc

Approx 10,400cc x0.7 = 7,280cc.(70%) what will this support on pump fuel and e85?

My spreadsheet is saying 720ish rwhp needs ~5500cc effective on pump fuel 10.5 AFR/0.715 Lambda, add ~30% for ethanol.

Before anything else, be aware many pumps will internal relief or fall off heavily at a final outlet pressure 7+bar you need something specifically specced for those pressures if you want to run 5 bar base pressure.

I'd say their suggestion is a combination of how significant the actual dead time is as a part of the cycle time and trying not to send fuel out the open exhaust port. Dead time is taking up something like 20% of your cycle at 8500rpm. They may have concerns around heat dissipation of the injector drivers although i would hope most ecus could run them near/at 100% for brief periods repeatedly. With significant WI my plan (wouldn't do this if running a business) is probably the peg high flowed secondaries and secondary injectors in a modified primary rail, likewise will probably peg factory injectors on a 7MGE+T, I may add an upstream facing ref spike at turbo outlet and 3 port MAC to pump a few more PSI of rail pressure at WOT 😁 with significant WI.

Assuming you are carrying peak power through 8500rpm with the new upper manifold with a dead time in the order of 1.3ms, with a couple of psi regulator sag with your 850/3000cc combination at 3 bar base you will be using about 78%DC.

if you bump up to 4 bar base, again assuming at least a bit of sag you are around 70%DC on pump fuel.

5 bar base with a touch of sag around 65%DC pump fuel.

The last two are probably a bit optimistic as dead times will increase with higher rail pressures.

Sounds like 1700cc primaries may be the go if you want ethanol.

I could probably add a few comments to the spreadsheet I have and send it to you. Not many people have inputs for variable peak power rpm, dead time, injector flow rated pressure, revised rail pressure, square root orifice flow law correction factor. In saying all that you are still running on some broad assumptions regarding required air flow for power and flow efficiency of the engine.

Hey thanks for the above, very helpful and yes def appreciate you sending over the spreadsheet. Sent you a pm in this regard.

What would the cc requirements be for 700ish hp if the with 10afr/0.68lambda? dont worry if the logic can be worked out on your spreadsheet.

i was thinking of running 4bar base fuel pressure and 2bar boost so a total of 6bar. Does this mean injector cc deliver-ability will be whatever 6bar shows on the injector data for flow?

I dont think asnu do 1700cc injectors, the biggest they have is 1500cc.
at 4bar the asnu data suggests - 1748cc of flow
6bar the asnu data suggest - 2117cc.

You can tweak most of that in the sheet. I may have been a bit optimistic with the specific power figure, 10.5 for that and 3 bar absolute (2 bar boost) should probably get you close.

To be very clear for everyone injector flow only relies on rail to manifold differential pressure, which at peak power, assuming your pump "keeps up" will be base fuel pressure likely minus a few PSI of "sag", basically because the regulator is a physical orifice/diaphragm/short spring it won't hold dead on the same pressure across the entire fuel demand range, at key on/idle/low load the spring is more compressed trying to bypass almost the entire pump flow, at full power the spring is relaxed a bit as the reg has to restrict outlet flow so pressure isn't dead on. A really long spring or solenoid coil assist could improve that but ecu fuel pressure compensation is easier to implement. This, combined with potential pump shortfall is why some people see unrealistic VE numbers near full power on non-compensated ecu setups.

it’s generally accepted that more appropriate total injector rates of 7,500cc for pump gas and 10,000cc for true E85 would be preferred. The goal being to having the injectors operating with excess capacity in reserve at the full power demand you’re shooting for.
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