Twin pump fuel supply

Sam44

Member +
Hi all this is my first post so here goes.

I've searched this subject on here and could find any results, if it has been covered in the past.

I've been researching just how far the fuel system has to be developed to provide good fuel delivery rates (pressure and flow volume), and at what power levels does this affect.
Threw this research it has become apparent that the main areas are fuel pump delivery flow rates, fuel filter restriction, fuel rail restriction, fuel temperature.

After emailing some of the Evo, as well as the gtr and supra lads, and looking threw there site this modification seams to yeild the best results for money and time spent.

Twin high volume fuel pumps GSS342 walbro pumps in this arrangement can do upto 500hp at 60 psi delivery pressure. Side note here, most factory OEM injectors max out and provide no further increase in delivery volume above 40psi.
High flow 5 to 10 micron fuel filter.
High flow fuel rail.

In addition this system has the safety and reliability factor of having a spare pump should 1 fail.

Has any one done this on a starlet plus info\build thread if so?. Please

Thanks sam
 

Attachments

Last edited:

Jay

Admin
Hi Sam,

Only going on what I've seen over the years the stock injectors and pump support 200-250 bhp, this is based on crude tunes with increased fuel pressure to support increased boost on TDo4 with no management. You just add fuel as you need it in these cases. Cowboy tuning does highlight the basics.

After that folks get concerned that the injectors are running 100% or the original pump is old and tired (bit like myself these days) so Walbro's and larger injectors are swapped in. Really depends on your management, if you have control over the injectors then it makes it a lot more tunable.

These are small cc engines so fueling demands are going to be a fair bit lower than top end Supras and Subarus. A lot of the big power builds are just using upgraded pumps, injectors, adjustable regulator and the odd larger fuel rail.
 

Sam44

Member +
Thanks for the reply jay.

What I'm experiencing is slight topend Drop off in fuel pressure at around 6k+rpm I'm running a fixed fuel pressure of 40psi on a civic b16 aftermarket high flow fuel rail, 372cc denso injectors (3sge), and a kemso fuel pump. I've also swapped the fuel pump and used a standard 4efte pump (the fuel drop becomes higher). It's running on the standard new fuel filter.
This is affecting power levels (hp leveling off torque drop off)

This issue has only just become a problem at from around .8bar and really showing up at 1bar of boost pressure.
Tank temps have been recorded at close to 40deg from may to now.
Injectors are operating around 70%

I'm setup on a 4efe at 1bar on a tdo4hyb (13t in size 11blade race billet wheel and 9blade exhaust turbine heavily ported exhaust side) at 1bar on standard pump fuel. My ems is a piggy back aem unit.

I've also found some very interesting research on fuel temperature affecting fuel octane and power levels by impacting inlet charge temperature.

It reads for every 7deg reduction in fuel temp can bring 1hp to the engine proformance, if the charge temps have been setup correctly. One thing to remember on the 4e ep91 is it runs indirect, batch firing injection so fuel vapourisation is a quality that contributes to how these operate, so is cam timing.
 
Last edited:
  • Like
Reactions: Jay

Sam44

Member +
There starting to hit and go north of 13 afr it was set to @.8bar of boost to 10.8 afr on wot.
Exhaust temps also on a steady sharp increase. I'm running a twin plate Audi S80 sport throttle, on the standard ep91 UK potentiometer (tps). The fueling increase at this point becomes a big jump up to hit target afr.
 
Last edited:
  • Like
Reactions: Jay

Jay

Admin
At a guess the TDo4 is coming into it's effective range at a 1bar of boost and starting to push some proper air. You can look at compressor maps to see what I mean but on a fueling run you can usually tell when a turbo is starting to boogie. Below a bar the average TDo4 doesn't have the same pull if you know what I mean. Soon as you hit a bar, the smiles start :)

If I was seeing 12's or 13's I'd be dialing more fuel in. It's better to have too much than too little. Especially if you are running stock 4EFE internals, you will be running the risk of detonation. The increase you are seeing in exhaust temp reflects this - the mix is running lean and hot - perfect conditions for knock.
 

Sam44

Member +
Very much agreed the difference from .8bar to 1bar in pull, and gforce recorded on my aem logger now from .7 to 1bar is alot bigger also the fueling in this range has been stepped up, along with the ignition advance. REAL TURBO SERGE. I'm hoping close to tdo5 16g torque figures. The fueling difference is alot this is were the fuel pressure problem starts. Estimated hp around 220hp hoping for more with the mods fitted.

I'm after the anti surge housing for the tdo4 13t if any body can help me. To save the thin 4efe rods and spread the torque across the rpm range.
 
Last edited:

SKINY

Lifer
Talking tank now, Phil seen issues during hard corners and 1 particular chicane on our local circuit. The fuel was basically running away from the pump because there's nothing special in the way off baffles in them, I experienced it a few times myself on hard corners on the way to work.
Maybe something else to think about unless your for using a proper baffled cell :)
 

Sam44

Member +
Yeh skinny that's a great idea. As the cornering g this thing can hit is exceptional. A baffled sump Im running with a home made windage tray, for this exact reason.

Another thing to add: I've tested the flow rate against pressure of my denso injectors 372cc light green 3sge. The peak pressure at which the injector does not flow any more fuel is 40psi.
 
Last edited:

Sam44

Member +
Just picked up on this, does that mean you are running 1:1 instead of rising rate?
Yep 40psi set pressure 1:1. the injectors are operating good in the lowwer rpm range. I've reduced inlet charge temps as far as I can go affecting fuel vapourisation. with this I saw a rise in hc, and co (unburnt fuel) in the exhaust emissions at an already set state of tune. There was also an increase in egt. the only way to bring things into balance was to alter fuel pressure atomisation and cam timing by means of an adjustable pully and a fpr. As soon as my corolla tubular manifold comes I'll fit this 4efte inlet cam that has slightly more lift on it also. (yet to reduce fuel temps. Things to come). I'm running a 76deg factory aem paseo coolant thermostat.

My standard map sensor is also positioned directly onto the inlet manifold giving a 1:1 throttle response on the map signal the best place was directly behind the throttle body. This provided a better out of boost and initial throttling map response allowing me to go leaner than I could before (the spool up times were sharp and fast) +the throttle\power control with the map sensor position and twin Audi throttle plates is a big improvement on standard Toyota setup.

Audi a80 sport (S80) 5cylinder 1990 52mm twin plate throttle body.
 

Attachments

Last edited:

Sam44

Member +
There are reasons why the OEM standard map sensor is positioned the way it is in the place it is in reference to the mainfold location and on a vacume tube.

Also the cam timing directly affects ignition timing by way of the distributor, and sensors that are driven off the exhaust cam.
Before carrying out these mods a good understanding of the system/systems is required.

I'm hoping the dual in tank fuel pumps and high flowing system including placing the fuel filter in a cold air stream and having a fuel cooler on the return to tank line has the desired affect of helping maintain topend rpm power levels and reduce detonation risk also cooling inlet charge temps increasing engine torque put.

I will put up further pictures and results as the system is developed.
 
Last edited:

Jay

Admin
I'd say it's worth trying an adjustable rising rate regulator. Under boost you should see more fuel which should both iron out your lean condition and cool the exhaust gases.

It's usually enough for the 4efte to see overfuelling on local cowboy tdo4 setups.
 

Sam44

Member +
I'd say it's worth trying an adjustable rising rate regulator. Under boost you should see more fuel which should both iron out your lean condition and cool the exhaust gases.

It's usually enough for the 4efte to see overfuelling on local cowboy tdo4 setups.
The fuel pressure regulator that's on her at present is the fse 1bar raising rate regulator with the vacume pipe off. The map fueling map was hit quite hard by the sudden raise in fuel pressure out of boost upon throttle opening. There was a dip in hp around 1700rpm to 2500rpm at this point the ECU was recovering the feuling afr. This can be seen on most 4efte and 4efe Dyno graphs. It comes down to a mechanical regulator operating in a electrical world (regulator and ECU). I fitted a vacume chamber inline on the vacume pipe to the regulator at first this helped delay and slow down the raise in fuel pressure at this point and also when boost came in helping the ECU recover/manage the afr better soon. A fantastic mod for every one. Better mpg was seen in around town driving mainly stop and start traffic the fuel reg was not dumping in fuel. Also boost build/spool up was better again the fueling didn't raise quicker than it had to.

The vacume chamber I use was off the VW Passat 1.8 20v


The way the fueling and ignition tables are set up on mine any drop or rise in fuel pressure upsets things. Leading to big increment adjustment jumps. Not so much ignition advance because of the flex in the cam belt and again a mechanical distributor, I've had to keep ignition advance on the safe side.
One of the problems with running injectors at peak pressure will be the fact that the injector is under high load this will reduce the injector service life I would expect and also things will get hot another reason for the fuel cooler. The injector is at the business end of things.
I could and might still use the system employed on the 3sge engine using an electrical controled Shut off solenoid valve in the vacume line with the fuel pressure regulator, this allows the fuel pressure rise to happen further up the rpm were it's needed (boost build) and not at initial throttle open. I could remove 15psi off the injectors and pumps out of boost lengthening the in service life.
 

Attachments

Last edited:

Jay

Admin
Hi Sam, by the sounds of it you are going to have to forgive my agricultural approach. I've been using my eyes, ears and right foot to set them up in the past - all these specific measurements don't mean a great deal to me but as ever I'm willing to learn new things :). As a sidenote, can I ask how you are data-logging the info, I wouldn't mind knowing what kit is involved just. Also what sort of dyno time are you getting or is this road tuning?

Generally if you are getting too much fuel with the RRFPR on cruise and low end conditions you could just trim the fueling down in the necessary areas. It will help throttle response and drivability. I've used the old skool Apexi SAFC, older AFC and the really old HKS F-CON's equipped with GCC units in this way. I was taught that upping the fueling mechanically and trimming it down electronically was the safest method. (I've never ventured into E-manage or the likes as I've never really had the brain for it but I suppose there's time yet).

Alternatively install bigger injectors?

If you are losing the fuel up top you need to add more and 372cc isn't the usual upgrade (440's seem to be the go-to for many).
 
Last edited:

Stu-

Member +
I've setup multi pumps on a few customers cars over the years, but mainly using a surge tank supply rather than multiple pumps into the stock tank. I've controlled the pumps via SSR's and PWM so the pump speed can be controlled which helps keep the fuel temps down and prolong pump life. Usually I just watch the measured rail pressure and then adjust the pump(s) speeds to suit.
 

Attachments

Jay

Admin
Aye, a swirl pot would sort the potential cornering issue Skiny mentioned too.

Stu those look like very neat installs, any chance of an overview of which components are needed/recommended to make that sort of modification on a stock vehicle? Just thinking a lot of these cars are suffering from rusting fuel tanks so it might prove useful to have an alternative to the standard systems.
 

Sam44

Member +
I've setup multi pumps on a few customers cars over the years, but mainly using a surge tank supply rather than multiple pumps into the stock tank. I've controlled the pumps via SSR's and PWM so the pump speed can be controlled which helps keep the fuel temps down and prolong pump life. Usually I just watch the measured rail pressure and then adjust the pump(s) speeds to suit.
Definitely could be an option I'll look into the supporting features on the aem piggy back and how versatile the pwm tables are. I was going to use the pwm tables to control the boost build instead of the anti surge housing, as well as possibly the fuel pressure regulator control solenoid to unload the injectors and pumps.
Hi Sam, by the sounds of it you are going to have to forgive my agricultural approach. I've been using my eyes, ears and right foot to set them up in the past - all these specific measurements don't mean a great deal to me but as ever I'm willing to learn new things :). As a sidenote, can I ask how you are data-logging the info, I wouldn't mind knowing what kit is involved just. Also what sort of dyno time are you getting or is this road tuning?

Generally if you are getting too much fuel with the RRFPR on cruise and low end conditions you could just trim the fueling down in the necessary areas. It will help throttle response and drivability. I've used the old skool Apexi SAFC, older AFC and the really old HKS F-CON's equipped with GCC units in this way. I was taught that upping the fueling mechanically and trimming it down electronically was the safest method. (I've never ventured into E-manage or the likes as I've never really had the brain for it but I suppose there's time yet).

Alternatively install bigger injectors?

If you are losing the fuel up top you need to add more and 372cc isn't the usual upgrade (440's seem to be the go-to for many).
On this setup The 295cc 4efte units maxed out (80%) around 160ishp predicted off boost levels. The next step up was the 372cc which I wanted to move up in increments on OEM denso units to get good low rpm injector duty.
I'm running the 4efe engine modified very specific down to each and every component for both proformance and mpg which equates to engine efficiency. The target is 230 to 250hp 4efe modified on pump fuel at around 35 to 40mpg, with a high torque output equal to the 5efte table top torque graph starting from very low rpm and holding till 6kpeak because of the heavy 4efe pistons. The 4efe is more widely available plus it gives great hp to money ratio (hp giver) just lacks torque.
I wasted alot of time road maping the setup using the raising rate regulator, and to get the low rpm power constant as well as better mpg and temps. The increase in temps showed them self's after a day's run mainly around town running. Both engine inlet and exhaust temps increased (engine temps showed them self's with an increase in rad pressure). With fuel pressures all over the place and not at all consitant,resulting in really bad mpg, also very hard to accurately setup fueling. At this point it became apparent I needed to run a fixed fuel pressure (but at what pressure). After fixing fuel pressure. temps became more stable and lowwer around town, lower rpm as well as boost build fueling became easier adjust as well as power produced increased in these areas. The only issue then was peak power level fuel pressure.
I'm road mapping using the aem vds to help predict power output. I've not yet had it on the Dyno Hoping to soon once all the many little things are on point.
I'm running the aem vds and aq-1 logger.
It takes experience to tune the way both you and I do, using these extra units helps finally tune the areas we can only access on the odd occasion. As you know this takes hours of road running.
Dyno graphs are good but there only a 1 off run not real world stuff.

I'm also running a high flow cat so my minimum afr target is 12.2
 
Last edited:

Sam44

Member +
Aye, a swirl pot would sort the potential cornering issue Skiny mentioned too.

Stu those look like very neat installs, any chance of an overview of which components are needed/recommended to make that sort of modification on a stock vehicle? Just thinking a lot of these cars are suffering from rusting fuel tanks so it might prove useful to have an alternative to the standard systems.
Yeh jay definitely a great mod and very neatly installed

stu do you install/use 1 way check valves directly after the 2x pumps.
I'm just buying all the parts required to install the 2xpumps now.


I'm firstly looking into low cost and time modification. None invasive.
An idea would be to fit the 2x uprated walbro pumps on either end of the tank this would help counter fuel Serge to some extent.
 
Last edited:
Thanks for the reply jay.

What I'm experiencing is slight topend Drop off in fuel pressure at around 6k+rpm I'm running a fixed fuel pressure of 40psi on a civic b16 aftermarket high flow fuel rail, 372cc denso injectors (3sge), and a kemso fuel pump. I've also swapped the fuel pump and used a standard 4efte pump (the fuel drop becomes higher). It's running on the standard fuel filter.
This is affecting power levels (hp leveling off torque drop off)

This issue has only just become a problem at from around .8bar and really showing up at 1bar of boost pressure.
Tank temps have been recorded at close to 40deg from may to now.
Injectors are operating around 70%

I'm setup on a 4efe at 1bar on a tdo4hyb (13t in size 11blade race billet wheel and 9blade exhaust turbine heavily ported exhaust side) at 1bar on standard pump fuel. My ems is a piggy back aem unit.

I've also found some very interesting research on fuel temperature affecting fuel octane and power levels by impacting inlet charge temperature.

It reads for every 7deg reduction in fuel temp can bring 1hp to the engine proformance, if the charge temps have been setup correctly. One thing to remember on the 4e ep91 is it runs indirect, batch firing injection so fuel vapourisation is a quality that contributes to how these operate, so is cam timing.
some good information from the others
based on the above, i've wondered about your fuel pump?...is this a reliable brand?, they are a lot of fake and cheap pumps out there---may you can try to genuine walbro
in the starlet community much can be achieved with a rrfpr, larger injectors and upgraded fuel pump---again, reputable brands are very important here...you can also double check the wiring to the fuel system, these are old cars now
there is generally no need for exotic fuel delivery set ups for the average project---they do have a place though if someone is going over and above
 
Top