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Discussion Starter · #1 ·
Last week I learned that a lot of fuel pumps have a built-in bypass that limits a fuel pump to a maximum of 63psi no matter how much is commanded - basically 20psi of boost is the limit.

I reviewed some of my log files and sure enough I'm commanding 75psi of fuel pressure (32psi boost) but it's limited at 63psi in the log files...aarrgg.

The discussion then went into what pumps don't limit the output and what pumps should I get that can flow enough for 1200-1300 crank HP (1000 RWHP) and the 450lph pumps were brought up. There are three from TI Automotive (Walbro) but one is not made for boosted applications due to the 63psi limit while the other two can produce over 100psi of fuel pressure. Something else I learned from my dyno tuner (Chad) is that not all 450's have built-in check valves so they cannot be used with more than one pump otherwise the fuel can back-feed into the other pump thus loosing pressure/volume.

Chad told me that their "Hellcat" pump does have the internal check valve and that's what he uses for multiple pump setups.

I had ordered what I thought was the correct pumps for my application the 450 "high Pressure" (p/n F90000274) but Chad wasn't familiar with this p/n so he told me to get the Hellcat Pump (F90000285) b/c he knew this had the internal check valve so I also ordered these pumps. I tried calling TI Automotive to get the real answer from them but the phone number listed on their site was a dead number.

Yesterday I received both 450lph pumps from Summit: the 450 "high Pressure" (p/n F90000274) and the Hellcat Pump F90000285.

Looking down inside the pumps through the inlet tube the construction of both pumps look 100% identical. There "looks" to be a check ball type feature way down inside of both pumps but unless I dissect them I still can't be 100% sure enough in that is what I am seeing. Based on what some people have said the (p/n F90000274) does have a check valve. If they both have check valves in them I don't know what the difference in design is between these two pumps and why TI Automotive offers the same type of pump unless the internal motors are designed differently.

Side Note:
If anyone is using an On3 Triple Fuel Pump Hat made for their 320/340 pumps these 450lph pumps DO NOT work with their hat, the pumps are located too close to fit. I spent well over an hour fabricating/milling the locating plate that holds all three pumps in order to get the 450 pumps to fit side-by-side and I had to mill off the plate .40" to make it thinner. The same issue may happen with other brand pump hangers, so keep this in mind. The issue stems from the bottom portion of these 450 pumps are larger than the body of the pump and the pumps would hit each other and not fit down far enough and not fit into the machined hole in the hat. So do your research on pump hats before buying.


The car now has three 450lph Hellcat pumps so the fuel system should be ready for another dyno session in March.

ks
 
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Ti Automotive makes five fuel pumps using that Hellcat form factor, Kevin. The part numbers and corresponding specs look like this

Form Factor..... Part #.... ... Flow.......... Pres Relief...... ... MAX PSI

Hellcat ..........F90000262.. ...405 LPH............Yes.....................87 psi
Hellcat.......... F90000267... ..430 LPH.............Yes.....................87 psi
Hellcat.......... F90000274..... 430 LPH............ Yes ..................187 psi
Hellcat...... ....F90000285.... . 470 LPH........... Yes....................150 psi
Hellcat....... ...F90000295 ... ..540 LPH............ No....................150 psi

This table is an F90000274 pump being run at 12 and 13.5 volts. The pump goes to a zero flow at 160 psi

Font Number Parallel Screenshot Circle



This is a pump flow graphic at varying pressures up to pump stall and the voltage and amperage required to drive the pump;

Rectangle Slope Plot Triangle Font


TI Automotive publishes this data for all their pumps to help us select the proper pump for our application.

A worthwhile data point to remember is the amperage to drive these pumps at elevated fuel pressures, our electrical system's ability to power the pump at these performance levels, and of course, the impact the additional head has on their flow performance.

Considering where TI indicates the pressure relief blows off on a F90000274 pump, the performance graph seems to indicate they test pump performance without a working check valve.
 

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Discussion Starter · #3 ·
Ti Automotive makes five fuel pumps using that Hellcat form factor, Kevin. The part numbers and corresponding specs look like this

Form Factor..... Part #.... ... Flow.......... Pres Relief...... ... MAX PSI

Hellcat ..........F90000262.. ...405 LPH............Yes.....................87 psi
Hellcat.......... F90000267... ..430 LPH.............Yes.....................87 psi
Hellcat.......... F90000274..... 430 LPH............ Yes ..................187 psi
Hellcat...... ....F90000285.... . 470 LPH........... Yes....................150 psi
Hellcat....... ...F90000295 ... ..540 LPH............ No....................150 psi

This table is an F90000274 pump being run at 12 and 13.5 volts. The pump goes to a zero flow at 160 psi

View attachment 176380


This is a pump flow graphic at varying pressures up to pump stall and the voltage and amperage required to drive the pump;

View attachment 176381

TI Automotive publishes this data for all their pumps to help us select the proper pump for our application.

A worthwhile data point to remember is the amperage to drive these pumps at elevated fuel pressures, our electrical system's ability to power the pump at these performance levels, and of course, the impact the additional head has on their flow performance.

Considering where TI indicates the pressure relief blows off on a F90000274 pump, the performance graph seems to indicate they test pump performance without a working check valve.
EXCELLENT INFO! I was trying to locate the differences in flow for the different pumps/part numbers so I could compare and understand the differences but couldn't find it anywhere on their site. Gotta link to the data you have? I still can't find that data anywhere and I still can't find a flow graphic for the 285 pump.

Here's the 285 which I ended up purchasing but still doesn't show the info you posted above:

Fuel: GAS & E85
Horsepower: 900+ at 60PSI, naturally aspirated applications
Over All Pump Length: 131mm
Main Housing Diameter: 39mm
Lower Housing Diameter: 50mm
Fuel Inlet Diameter: 11mm OD
Fuel Outlet Diameter: 11mm OD
Flow Rate: 470lph @ 40psi (120+ gph)
Test Voltage: 13.5 Volts
Industry Tag: Walbro 525 – Hellcat Pump

Since I was unsuccessful in finding the comparison data that you posted I am very thankful that I bought the 285 pump and sent back the 274 based on the MAX PSI value.
Concerning the internal check valve that seems to be required when running multiple pumps only the 285 specifically states "internal check valve" but I read that on another site that supposedly sold these TI pumps.

If this info hasn't been posted before hopefully this will help someone.

ks
 
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TI Auto has most of the info on its site Kevin, however it is not intuitively obvious where they have it located. Here is a link to a significant chunk of it; click here => https://aftermarket.tiautomotive.com/technical-info/#flow-charts.

Discovering the rest of it is akin to playing that original computer game Colossal Cave. Colossal Cave, if you recall, is the original classic text-based adventure released in 1976 by Will Crowther for the DEC PDP-10 computer, which predates most of us on the site here. In the game, the player explores a vast and extensive cave network, seeking treasures within. Along the way, you will encounter a variety of tools and characters, some of whom will attack you and some of whom will help you. It is sort of the same thing on the TI Automotive website, but without the tools and characters — the game is more fun.

If you have never experienced the original text-based game that literally started the gaming industry in the mid 1970's, you can get a taste of what it was like back then in a demo version available here => Colossal Cave When Colossal Cave was first released, computers were ASCII terminals on an RS-232 link back to the minicomputer they were attached to. There were no graphics or colors like we have today so the developer(s) had to build the video images in your mind with words — quite a feat and quite a game. If you have never experienced it, it is worth a few minutes to explore — it might actually help you on the TI-Automotive website. :)
 

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another thing to consider is that adding fuel pump dosent increase flow linearly, ie three pumps dont triple the flow of 1.
i made a 3 pump fuel assembly that bolts in place of a fuel cell filler hat. it has 3 274 ti pumps. a common rail drilled to 13/16(-10 thread drill size) about 2 inches long with 1/4 npt drill size leading to it.
testing on car using my fuel lines( -10 feed -8 return) and regulator set to 40psi i measured the fuel flow returned at the tank. with 1 pump i got about 95% of advertised fuel flow. the second pump added about 80% of advertised. the third added about 60%. the pressure at the fuel rail raised about 2 psi with the 3rd pump. there are 2 things i can think of that contribute to this.

1. flow restriction between pumps and rail that adds to head pressure which makes pumps flow less
2. voltage drop which lowers output.

i measured amperage when i did this. individual pumps drew 20-21 amps. all combined about 55-57. used an old school battery charger to try and keep voltage above 12.5.
final results for me are that at 20lbs boost and 210 injectors fuel pressure is steady to 80%dc at 95%dc fuel pressure is about 4psi down.
 

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Discussion Starter · #6 ·
The difference in flows may be from how the pumps are feeding the rail. All three pumps should feed into a large reservoir and keep this under pressure evenly (all things being equal with the pumps) then a fuel line should tap into the reservoir. If there is no reservoir or it it's too small then the flow rates of the pumps could be affected.

ks
 

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Ashford nailed it, Kevin. When you look at the flow chart for a single pump and read the head the pump is pumping against, you will see the voltage and amperage the pump is drawing. If we increase the head and reduce power (voltage or amperage), then the system will experience a corresponding reduction in volume flow (mass flow). Because the metric used to fuel our engines is a mass flow metric, AFR (lbs of air per lb of fuel), the engine operation is sensitive to these sorts of power delivery perturbations.

With a finite delivery orifice and a computer-controlled duty cycle (injector on time), the addition of increased pumping capacity will not result in a linear increase in delivered fuel mass at the injector or measured pressure in the fuel system. When you add to this the increasing load it places on the fuel pump's electrical system, you've added yet another dimension to an already complex physical process.

The best fix I have found is to run the fuel system with the most robust power delivery capabilities we can package into the back of the car, run the base system pressure at 39 psi, and select injectors that will allow you to operate at less than a 75% duty cycle. While nothing is perfect, this does allow for an operating fuel system pressure of only 60 psi while using up to 20 lbs of boost. If you are looking at a race scenario where you will be using 25, 30, 40 psi of boost and higher, you will need to go to a mechanical pump. The power draw of an electric pump goes off the wrong end of the chart and becomes very difficult, if not impossible, to consistently control and supply.

There are other challenges that also appear along the way. A big one is the low speed, read idle, flow characteristics of the injectors. Some big injectors, not all, and usually older design big injectors can have poor idle characteristics because the injector flow at low pulse widths becomes both non-linear and inconsistent with the same injector's flow at higher pulse widths.

The basic problem is attempting to build a race engine power level for a daily driver type application. We simply run out of operating range with some components. Either the low-speed fuel delivery is inconsistent, or the high-speed fuel delivery is beyond the operating range of the components (pumps and injectors). The basic admonition is to be careful what you wish for and attempt to build.
 

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Discussion Starter · #8 · (Edited)
Ah, I misread what he posted and thought the measurements were of each pump in parallel indicating that the output of each pump was different than it's neighbor.

Reading what you mentioned about low speed characteristics (idle) the negatives that were pointed out wouldn't be present if using a single pump for a street vehicle and activating multiple pumps when required.

I'm curious how would the returning fuel to the tank affect what is seen at the inj?
I'm thinking as I type this so who knows what is going to come out but: would having a second regulator after the inj's help stabilize pressure at the inj's at all? I can see that this wouldn't help the volume of fuel entering the fuel tank upon returning to the tank b/c the issue starts at the pump(s) but I can almost see that a second regulator after the inj's may stabilize psi at the inj's....

More thinking:
In order to triple the flow the system would need no restriction - which would hint at separate fuel lines, return lines, but still have a common reservoir that feeds the inj's.. that's gets messy if I'm on the right track..

ks
 
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