Walbro 340 vs TT340 (Aeromotive 340)

[TTipe]

First, this is a long post..... so read on if interested.

My goal here is to present in-car flow tests between these two pumps. Fuel lines are stock. Pump has been hot-wired. Flow tests were done by unhooking the return line down by the frame near drivers side motor mount and aiming end of the line into a 2.5-3 gal graduated "car-wash" bucket I got from Wal-Mart. I have the battery hooked to a battery charger to simulate the alternator running as it would normally be while driving (or racing). I have a Accufab adjustable FPR on stock rails. I have a Snap-On Fuel pressure gauge hooked up on the end of the stock fuel rail.

Pump # 1 is a Walbro 20000169 (I'm told this is/was the same pump as the ones Walbro used to modify the base for the buick application that everyone refers to as the Walbro 340) The only difference is the foot of the pump was changed so an off-the-shelf pump would work for the buicks instead of modifying the base of ford pumps.

Pump # 2 is a TurboTweak 340. I'm told these pumps are basically the Aeromotive 340 everyone wants.... but comes in a plain white box. The are supposed to flow exactly the same as the Aeromotive.

Test # 1 was with Pump #1 installed in my GN... as I began running some flow tests yesterday to chase a high BLM on my TT 6.0 WB chip. I am also running 80# injectors and feel there should be enough flow @ boost to supply injectors with enough fuel to get to 80% duty cycle or more.

Regulator adjusted up until the gauge showed 70 psi (this would simulate the flow the pump would be putting out at 27 psi boost if base FP was set to 43 psi)

Put a graduated bucket under the unhooked return line.

Put a sharpie mark at 1 gal and 2 gal to make it easier to see.
Great start for this type of experiment.I have a concern about the Walbro 20000169 as tested. If the fuel inlet is offset from the center of the unit circle of the pump body,then I wonder if the fluid is accelerated as much within the pump body as the 340m (with the inlet in the center of the pump body). Bottom line I wonder if comparative curves have been established between the "mustang" pump and the 34om at equal voltages. Also the worst flow resistance in the stock fuel system is in the lines where they snake around on the frame rail. If the return line was disconnected before the frame rail I suspect that a large amount of flow resistance was removed from the return line (just thinking out loud). EMF produced from your charger (@ 5o amp) would be nice to know. Voltage is what increases output. 65 gal/hr is about what I calculated for a 340M using flow curves (volume @ pressure) and voltage. I could get to where you are with the 340m (62/63 gal/hr) at 15.5 volts in the tank. I was skeptical of how the curves were recorded (with a fuel system in place or not). I am skeptical about whether or not the Aeromotive out performs the 340m. The case size of each is the same. The wire gage and wire coatings are probably the same. I'll bet the pump volumes ( gerotor/roller vain) are the same. If the above is true then the pump rpms are the same. If all this stuff is the same I'll bet the pump outputs are very close. The way to eliminate all doubts is to test with fuel feeds, returns with a regulator and a controlled voltage supply. This gets rid of if ands/buts about the fuel system etc. You will then know which pump produces the most volume at controlled conditions. Once the winner is found then apply to the vehicle for evaluation. I am not being critical of your efforts and I think you have done a great job. Thanks for your time taken to help us all out.

Just another M.E.

Bat charger hooked to battery and on 10 amp setting for 1st test

It took about 1 min 23 sec for the 1st gal and 2:58 total for 2 gal....

Changed bat charger to the 50a start setting and ran test again....

1:13 for the 1st gal and 2:28 total for two gal.

Ok.... Now for my math.

Per Wikipedia, gas has a density of about 6.07 lb per gal.

Assuming I need at least enough fuel to get to 80 % duty cycle.... I get....

Fuel required:
80#/hr x 6 cyl = 480 # / hr x 80 % DC = 384 # / hr

Fuel available:

1st case - bat charger on 10 amp
2 gal in 2:58 = 6.07x2 (lb) / 2.9666 (min) X 60 (min) / 1 (hr) = 245 lb / hr

2nd case - bat charger on 50 amps
2 gal in 2:28 = 6.07x2 (lb) / 2.4666 (min) x 60 (min) / 1 (hr) = 295 lb / hr

So if my math is correct, I don't have enough fuel to get those injectors to 80 % duty cycle at 25 - 27 psi boost.

At this point I changed fuel filter and re-ran the test and achieved identical results on the 50A battery charger setting (my fuel filter wasn't restricting flow which was good)

Not happy with the results, I swapped in the TT340 pump and re-ran the flow test @ the 50A setting (Test #2).

Test #2 - TT 340 with regulator still set to 70 psi and battery charger on 50A setting.

It took 1:50 for 2 gal.

Doing the math:

2 gal in 1:50 = 6.07x2 (lb) / 1.8333(min) x 60 (min) / 1 (hr) = 397 lb / hr

Now we are getting somewhere! If you refer above, I figured out I needed 384 lb / hr to achieve what many would refer to as the upper limit of what you would typically want to "push" injectors to. The school of thought is to step-up your injectors if you need more than 80% duty cycle. IMHO, 80's are large enough to get a full weight car into the high 9's before they will need replacing.... or quicker if you are using alky too.

Bottom line is there is a nice (simulated real-world) difference in the old Walbro 340 and the newer Aeromotive 340 style pump..... 102 lb/hr difference at 70 psi.....

I have not had a chance to drive and see if there is any issue with my return line being too small with the new pump. The paperwork that comes with the pump states that some people have problems with the pressure being to high at idle. I set mine at 45 psi base fuel pressure just fine with the return line hooked up and flowing back into the tank without the car running. I have not checked the FP yet with the car running and vacuum line hooked up..... I will update this thread when I have driven the car more and checked the FP more.

Hope this helps some people.....

 

[TTipe]

Thanks for taking the time to experiment and share your results. A couple of things may taint the conclusions slightly. The highest fuel line resistance (not total resistance) occurs where the bends are down by the fuel rail. If the fuel was drained prior to the fuel return bends then system pressure is greatly reduced. EMF (voltage) from your battery charger is known??? The mustang pump with its offset inlet may not accelerate fluid like the centered inlet. The pump body looks to be the same dimensions as the walbro 340M ( inlet centers around the center of the pump body). This might lead me to believe that the windings, wire coatings , and the type and size of the pumps (gerotor / roller vain) are about the same. I did some calculations based on published flow/pressure/voltage curves for the 340m and found that 15.5 volts in the tank I could get 62/63 gal/hr. I was very skeptical about how these curves were developed thinking they did not reflect the load of our fuel system. I will be surprised and happy if the aeromotive produces sizable gains over the walbro 340m and good voltage.

Just another M.E.

 

[Ttype6]

After piddling with it some more... I do have FP issues at idle.... with everything cold... it will only adjust down to about 45 or 46 psi..... and seems to not want to go any lower.

You're comparing a 255 lph pump to a 300 lph pump. I don't understand why you are doing this. Of course the bigger pump flows more. These pumps have already been proven to flow more. The proof comes from all of the people who have modified or replaced their return lines to lower their idle pressure. The reason they've had to do this is because the bigger pumps flow more volume than the return line can accommodate at an idle. Now you know first hand that these pumps cause problems that have to be addressed. I can see from your previous statements that you were happy to see that the larger pump flowed more. In other words,your thinking was that bigger is better. Are you still thinking this?

 

[Ttype6]

I was not wanting to mod my return line. The closer to factory appearing, the better to me. I'm not a huge fan of all the bling if it doesn't add HP.

You're the guy I've been trying to protect from these bigger,and therefore better,pumps. Some people don't want to change things if they don't have to. Not to worry. All you have to do is drill the two Saginaw fittings on the factory return line to an ID as large as you can get away with. You'll be changing the ID of the line ,so it won't be something that any one can see. This larger ID will allow more fuel to return to the tank at idle which will lower your idle fuel pressure.

 

[Blazer406]

You're comparing a 255 lph pump to a 300 lph pump. I don't understand why you are doing this. Of course the bigger pump flows more. These pumps have already been proven to flow more. The proof comes from all of the people who have modified or replaced their return lines to lower their idle pressure. The reason they've had to do this is because the bigger pumps flow more volume than the return line can accommodate at an idle. Now you know first hand that these pumps cause problems that have to be addressed. I can see from your previous statements that you were happy to see that the larger pump flowed more. In other words,your thinking was that bigger is better. Are you still thinking this?

I'll spell it out for you since you asked.

In my case, I started this excercise as a troubleshooting adventure. Starting with my Walbro 255LPH pump. I datalogged a low boost pass and my WOT correction numbers were really high..... so I bumped up the overall fueling in the chip up to the max.....and was still getting WOT wideband 02 correction numbers really high. One of the things that can cause this is if the fuel pressure starts to tail off (regardless of reason). One reason is if the pump can't keep up. I know a Walbro 340 pump hot wired is capable of high 9's with alky (which I have). Since I was at low boost, I was not at that sort of power level.... hence....I shouldn't have had an issue...... so I flowed the pump at pressure to see what (lbs/hr) I was getting. I was seeing duty cycles in the mid 70's on my 80# injectors.

Once I got the flow data from the Walbro.... it was apparent I didn't have enough fuel flow for my 80's at that duty cycle..... so I decided to change to the Aeromotive style pump and flow test it back-to-back with the other pump to see how much difference there was. Ther aeromotive pump installed in my car flowing through stock lines does have enough flow to get to low-mid 80's on the duty cycle.... so, yes....it is better in my case.

I never went into this test to see if the aeromotive would outflow the walbro.... that was a given. I wanted to see the in-car real-world difference..... not some flow sheet from a bench test that doesn't as accurately as possible replicate the in-car installation. All that fuel line, the filter, the wiring, etc plays a role in how much or how little a fuel system will flow.

Nearly the absolute worst thing you can do to a boosted engine is to starve it for fuel. The fuel pump is one of the most important things to "oversize". So without a doubt... within reason..... bigger IS better. This is not the same comparison as a bigger cam..... or bigger heads..... or bigger headers..... etc.

 

[Blazer406]

You're the guy I've been trying to protect from these bigger,and therefore better,pumps. Some people don't want to change things if they don't have to. Not to worry. All you have to do is drill the two Saginaw fittings on the factory return line to an ID as large as you can get away with. You'll be changing the ID of the line ,so it won't be something that any one can see. This larger ID will allow more fuel to return to the tank at idle which will lower your idle fuel pressure.

Protect on.

There are many things on these cars which you can preach bigger isn't always better.... but fuel pumps isn't one of them.

I hope you don't blow up someone elses engine because you think a given pump is big enough.

I don't assume a given pump is big enough just because a flow sheet posted on the net says it is. I need to back that up with data to prove it is capable.

 

[Ttype6]

Nearly the absolute worst thing you can do to a boosted engine is to starve it for fuel. The fuel pump is one of the most important things to "oversize". So without a doubt... within reason..... bigger IS better. This is not the same comparison as a bigger cam..... or bigger heads..... or bigger headers..... etc.

Did you ever observe a fuel pressure gauge at WOT?

 

[Ttype6]

Protect on.

There are many things on these cars which you can preach bigger isn't always better.... but fuel pumps isn't one of them.

I hope you don't blow up someone elses engine because you think a given pump is big enough.

I don't assume a given pump is big enough just because a flow sheet posted on the net says it is. I need to back that up with data to prove it is capable.

The way that you chose to send fuel to your motor has created a problem that you have to fix. I would have like to have prevented that.
I make a lot of power on E85 and have a stock un-altered fuel return line.
Do you understand how I'm able to do that and still get all the fuel to my motor that it needs and not have idle pressure problems?
The data that tells me that my fuel supply is adequate is the hood mounted fuel pressure gauge that stairs me in the face.

 

[TTipe]

You're comparing a 255 lph pump to a 300 lph pump. I don't understand why you are doing this. Of course the bigger pump flows more. These pumps have already been proven to flow more. The proof comes from all of the people who have modified or replaced their return lines to lower their idle pressure. The reason they've had to do this is because the bigger pumps flow more volume than the return line can accommodate at an idle. Now you know first hand that these pumps cause problems that have to be addressed. I can see from your previous statements that you were happy to see that the larger pump flowed more. In other words,your thinking was that bigger is better. Are you still thinking this?

Anyone can tell you that the Aeromotive flows "300 lph" depending on EMF and total line resistance.There have been numerous curves published by people that have no idea of what "DOE" is (not including you).Bigger can be better if the fuel "system" will allow positive gains. I have worked on my system making improvements for years using different pumps starting back in the days of GS242. At what voltage was the aeromotive 340 rated at 300lph? These pumps have already been proven to flow more.

I have never seen any study to show volume at pressure and voltage that defined the flow system.I have had idle speed fuel flow excess with a 340m! The proof comes from people having to mod their return lines to lower idle pressure.

So now we are resorting to a Tangent line for flow curve across the pressure range of load?? Are you still thinking this?

No emphatically! We are talking about a system.I would prefer to fix the stock system first, then properly rate the pumps, which I have done. The sender was fixed, the rail was drilled out,the pump wiring was fixed (including the harness elbow in the lid of the pump) along with a proper hotwire kit along with drilled out return line fittings.In my signature you will see that I use a Denso 280 (twin turbo Supra) fuel pump. I don't like the weight of the denso on the sender (this can be dealt with). The Denso 280 pump was used on a factory performance car.The Supra is being run way beyond factory power on the Denso 280.Toyota is not going to release a pump that did not go through a rigorous validation plan else they would have major^2 warranty expenses.The Walbro has not been validated in any of our cars with all of our different fuel system concoctions. The pump itself is superior to the walbro for the long haul,but does require more wattage. The Denso is very comfortable above 16 volts and will static a set of 80's without problem.There is another site that compared just pumps and you will find the imformation useful. Just to be clear a "systems" approach is required and pumps are part of the system. There are are lot of poor imformation sources about fuel pumps and their capabilities out there that the Buick community buys into without question. False fuel system data has cost a lost of engine rebuilds.Thanks Blazer 406 for your valuable input.

 

[Blazer406]

Did you ever observe a fuel pressure gauge at WOT?

IMHO, a hood mounted FP gauge has a limited value to me. Under normal circumstances, you would only be concerned with the pressure at WOT during a run. I have enough stuff to pay attention to, that it would likely be unsafe for a driver to study a hood mounted FP gauge at WOT.

So to answer your question..... No I didn't have a hood mounted FP gauge. My car is more street oriented.... And as such....I try and hide what I can. I have no A-pillar gauge cluster, no console gauges, and my boost controller and Wideband gauge is mounted inside the glovebox.

I am about to finally get fuel and oil pressure data logging hooked up soon.

 

[Blazer406]

The way that you chose to send fuel to your motor has created a problem that you have to fix. I would have like to have prevented that.
I make a lot of power on E85 and have a stock un-altered fuel return line.
Do you understand how I'm able to do that and still get all the fuel to my motor that it needs and not have idle pressure problems?
The data that tells me that my fuel supply is adequate is the hood mounted fuel pressure gauge that stairs me in the face.

The issue I have by my idle pressure not being able to drop below 46 psi or so is not a big issue as far as I can tell. Apparently my chip has compensated for it , because I can't tell there is an isdue.

I respectfully disagree. A hood mounted FP gauge doesn't constitute "data logging"

I understand you disagree with my testing and my methods. That is why they make chocolate and vanilla.

 

[BEATAV8]

I think you have executed a fine example of a real world flow test here. People can argue that you have excluded this or included that, but in the end you ran the pumps throught the stock supply line and through a fuel pressure regulator to control the pressure (load) on the pump. Regardless of the details this is still useful and valuable information.

To me this test isn't about seeing that one pump outflows another, its about seeing what the pumps flow when you stuff them into a real Buick fuel system and see what comes out the other side.

 

[Jerryl]

Good test! Everyone has valid points.
One thing to remember on the return line debate . . . . with a running car, there is slightly less fuel returned . . . . so the size of the return line becomes less of an issue. What is interesting (if you think about it) . . . . at close to max engine performance, there may be very little fuel returned to the tank. Once rail pressure drops below the base regulator+boost setting, fuel will no longer be returned to the tank.

 

[Ttype6]

I never went into this test to see if the aeromotive would outflow the walbro.... that was a given. I wanted to see the in-car real-world difference.

The only way to get the information you want is to put the pump in a car and drive it in the real world while monitoring fuel pressure. Nothing else is real world. Nothing else takes the place of monitoring fuel pressure.

Nearly the absolute worst thing you can do to a boosted engine is to starve it for fuel.

You are aware of the importance of fuel flow.

IMHO, a hood mounted FP gauge has a limited value to me. Under normal circumstances, you would only be concerned with the pressure at WOT during a run.

So to answer your question..... No I didn't have a hood mounted FP gauge.

You are aware of the importance of fuel flow,but you think the only thing that can monitor it is of little importance.
You believe that the only time you need to monitor fuel pressure is at WOT. How do you do this?

I hope you don't blow up someone elses engine because you think a given pump is big enough.

How can that happen ? I monitor the only thing that matters. FUEL PRESSURE.

I am about to finally get fuel and oil pressure data logging hooked up soon.

This will give you the all important information you need.

 

[Ttype6]

To me this test isn't about seeing that one pump outflows another, its about seeing what the pumps flow when you stuff them into a real Buick fuel system and see what comes out the other side.

It shows that the one pump outflows the other. This was already known. What it doesn't show is the fuel pressure while a turbo Buick is drinking most of the fuel that the pump puts out. This is the only test that means anything. If the fuel pressure rises as it should,the fuel system is adequate. If it doesn't,you look at restrictions,voltage,and pump. The other variable is the fact that the same pump in a different car might not produce the same results.

 

[BEATAV8]

It shows that the one pump outflows the other. This was already known.

Nobody cares about that, the pump flow sales curves cover it. Your not paying attention to the data, or the stated goal of presenting data for in-car flow tests.

Typical walbro gss340 sales curve shows 273lb/hr @ 70psi and 10 amps (12V). That data comes from a bench.
In a real world Buick fuel system with 70psi and a 10 amp boost, the pump delivered 245lb/hr. That's the important information.

An Aeromotive 340 sales curve shows 417lb/hr @ 70psi and 13.5V. Also data from a bench.
This pump (TT340) in a real world Buick fuel system delivered 397lb/hr.

The data provides confidence and reason when deciding whether or not a prospective pump will be able to support a prospective fuel injector in a Buick, or as Blazer has used it to decide how much injector duty he thinks he can run before he tries to run it.

If Blazer had unlimited time money and resources he could start swapping and modifying components.

It may not be perfect data, but it's not bad data. It's certainly much better than no data.
It would be interesting to see how the Deatschwerks compares to the TT340 in this type of test, particularly since the sales curves for the two pumps are so close at 70psi.

 

[Ttype6]

Your not paying attention to the data, or the stated goal of presenting data for in-car flow tests.

The data provides confidence and reason when deciding whether or not a prospective pump will be able to support a prospective fuel injector

If this information is so important and so real world and so correct and provides so much confidence,you have no need to monitor fuel pressure. Throw away any gauge or transducer you might have.
As for me,I will continue to not pay attention to data by monitoring stupid fuel pressure. Please pray for me.

 

[TTipe]

Nobody cares about that, the pump flow sales curves cover it. Your not paying attention to the data, or the stated goal of presenting data for in-car flow tests.

Typical walbro gss340 sales curve shows 273lb/hr @ 70psi and 10 amps (12V). That data comes from a bench.
In a real world Buick fuel system with 70psi and a 10 amp boost, the pump delivered 245lb/hr. That's the important information.

An Aeromotive 340 sales curve shows 417lb/hr @ 70psi and 13.5V. Also data from a bench.
This pump (TT340) in a real world Buick fuel system delivered 397lb/hr.

The data provides confidence and reason when deciding whether or not a prospective pump will be able to support a prospective fuel injector in a Buick, or as Blazer has used it to decide how much injector duty he thinks he can run before he tries to run it.

If Blazer had unlimited time money and resources he could start swapping and modifying components.

It may not be perfect data, but it's not bad data. It's certainly much better than no data.
It would be interesting to see how the Deatschwerks compares to the TT340 in this type of test, particularly since the sales curves for the two pumps are so close at 70psi.

It is awesome to see folks running the numbers and asking questions.This is a great exercise and incentive for folks to get out their calculators and investigate. You made a statement

This pump (TT340) in a real world Buick fuel system delivered 397lb/hr. This imformation is meaningless without pressure and voltage. Do you recall if this pump was tested at 70 psi and 13.5 volts? If so then delivery volume was 59.25 gal/hr....(397lb/hr/6.07lb/gal)=59.25 gal/hr. The 70 psi breaks down to roughly 43.5 psi (static pressure + 26.5 psi boost pressure. It takes roughly 48 gal/hr to put a lightweight Regal through the traps around 123 mph (high 10-100% inj duty cycle with everything absolutely perfect which almost never happens and is not dependable).15% injector duty cycle left on the table supports adequate fuel delivery at minimum by GM calibration standards. If I were to assume that this test took place at 70psi and 13.5 volts then my hat is off to Aeromotive, but I have no curve or spread sheet that clarifies this.Aeromotive writes a disclaimer about the fuel system meeting undefined requirements for fuel filter flow, undefined interior surface line texture, having significant voltage to produce a target volume at some unknown pressure.You bet testing is necessary on the OE fuel system because there are tangeable values that can be grasped. The aeromotive pump may be slightly better than the 340m (and I can't find data to support this) but aeromotive is putting out sales jargon that would never be accepted by an OE, of course their audience is very generic and vehicle warranty is not a liability to them. I'll keep my 280.

 

[The Radius Kid]

The only way to get the information you want is to put the pump in a car and drive it in the real world while monitoring fuel pressure. Nothing else is real world. Nothing else takes the place of monitoring fuel pressure.

You are aware of the importance of fuel flow.

You are aware of the importance of fuel flow,but you think the only thing that can monitor it is of little importance.
You believe that the only time you need to monitor fuel pressure is at WOT. How do you do this?

How can that happen ? I monitor the only thing that matters. FUEL PRESSURE.
This will give you the all important information you need.

You seem to be a knowledgeable guy.
I am curious:

How do you choose a fuel pump that you that you feel is a good candidate for your needs?

 

[dvernst]

It shows that the one pump outflows the other. This was already known. What it doesn't show is the fuel pressure while a turbo Buick is drinking most of the fuel that the pump puts out. This is the only test that means anything. If the fuel pressure rises as it should,the fuel system is adequate. If it doesn't,you look at restrictions,voltage,and pump. The other variable is the fact that the same pump in a different car might not produce the same results.

You're such an easy target. This is good entertainment. Thank you. Ha!