BlowerWorks

I think all who view and study the attached fuel pump graphs will find enlightening. The excellent Excel graphs are the work of Mo Bandy. I never could have completed the graphs without Mo's help.

The first graph is that of a stock 1994 Corvette LT1 in-tank pump feeding a Vortech T-REX in-line fuel pump: interesting to say the least.

The second graph is that of the same '94 LT1 fuel pump feeding an in-line Vortech 'UNIVERSAL'. The T-REX pump has a right angle outlet using a banjo fitting and cap nut. The Vortech 'UNIVERSAL' in-line pump is straight thru - that's how you can tell which pump you have if running a Vortech S/C kit on an LT1.

The third graph is that of the Racetronix GSS-340M shown at 13.5vdc & 16.0vdc by itself: no in-line booster. Impressive to say the least. Note the sharp fall off after 60 psi - the point at which the 340's internal relief valve starts to open.

Then we substitute the Racetronix GSS-340M for the stock LT1 in-tank fuel pump and use it to feed the in-line T-REX. This graph clearly shows the advantages of using an in-line fuel pump booster when fuel rail pressures must exceed 60 or 70 psig. This graph also shows the flow capability of the T-REX as a stand alone pump.

The next to last graph shows the GSS-340M feeding assorted in-line pumps including the Racetronix GSL-392.

The last graph shows the GSS-340M feeding the GSL-392 and includes the pump amperages. Note how when used together the two pumps share the load: neither one working too hard.

My conclusion is the Racetronix GSS-340M is a great little pump and can make any in-line booster pump look good. The 340M can support a lot of HP by it-self: especially if you use the Racetronix installation harness. The Racetronix C4 pump harness, in my opinion, is a beautiful piece at a bargain price! If your fuel set-up includes a FMU running fuel rail pressures above 60 psi, keep the in-line booster and be sure to run the in-tank GSS-340M. Even the "whimpy" Vortech 'UNIVERSAL' looks good at 80 psi when fed by the GSS-340M. The in-tank GSS-340M feeding the in-line GSL-392 can support some awesome HP all at 13.5vdc. Note all Supported HP numbers use .5 BSF. A well tuned supercharged engine at 12.5 to 13.0:1 may achieve .45 BSF.

Hope these graphs 'put to bed' all your fuel pump questions. Regards Greg

LPDesRoche

Greg, those tests are very interesting and informative. I would really like to see a test with 2 GSS-340's run in parallel. Lots of guys run 2 of these via an intank setup Y'ed together feeding the factory fuel line with lots of success. I am curious as to how that performs compared to your other tests.

qwiketz

does anyone out there make a kit to allow you to install 2 gss 340's?

LPDesRoche

You don't need a kit, you can just worm gear clamp them together. Or if you want to do what I have done in the past you can weld a little tab onto the other side of the pickup tube 180 deg from the other fuel pump holder tab and set it there. Then just Y the two pumps together and feed the main line just like you would with one.

Lee

Bruce

Twin GSS340M pump here Y them together and feed a -10AN braided line and Y a -08AN to feed both rails.

BlowerWorks

We Can Do That !

Mr6spd

Great Data!!!!! It that all through stock (3/8") fuel lines? Is the stock fuel filter a significant flow restriction?

BlowerWorks

YES TO BOTH. IF YOU READ MY C4 "SEMI-WHITE PAPER" YOU'LL SEE WHY 3/8"id LINE IS NO IMPEDIMENT TO 1000+ HP. THE ONLY PROBLEM WITH THE STOCK FUEL FILTER IS IT MUST BE CHANGED OFTEN - LIKE EVERY 5,000 MILES. IT CLOGS EASILY WITH DIRTY FUEL. HOWEVER BETTER TO CLOG FILTER THAN INJECTORS. REGARDS GREG

Mr6spd

Thanks Greg. Your pump tests are the most useful data I have seen posted here, and are much appreciated. I'll email you for a copy of the semi-white paper.

I too am interested in how the Dual GSS-340M setup will perform.

BlowerWorks

THANKS FOR FEEDBACK MR6SPD - MUCH APPRECIATED. I ENJOYED RUNNING THE TESTS & ALSO LEARNED MUCH FROM THE RESULTS. I WILL RUN THE DUAL IN-TANK 340'S SOMETIME NEXT WEEK AND POST. ALSO THE RELIEF VALVES ON THE 340'S CAN BE EPOXIED CLOSED RESULTING IN A VERY SMOOTH GRAPH ABOVE 60 PSIG. THE RISKS IN SO DOING FROM A MANUFACTURERS VIEWPOINT IS THE DAMAGE TO THE PUMPS THAT CAN RESULT FROM DEADHEADING (CLOGGED FILTER ETC.)AND/OR THE RESULTING VERY HIGH FUEL RAIL PRESSURES THAT COULD RESULT FROM A PINCHED RETURN LINE. HOWEVER FOR THE KNOWLEDGEABLE RACER RUNNING A TURBO OR BIG CENTRIFUGAL THAT UNDERSTANDS THE RISKS AND PROPERLY FUSES THE PUMP(s) THE EPOXIED PUMPS ARE PERFECT FOR HIGH PRESSURE, HIGH HP OWNERS/RACERS. LEST SOMEONE READS THIS AND ATTEMPTS ON HIS OWN TO DO BEWARE NOT ALL EPOXIES ARE CREATED EQUAL. MANY DISSOLVE WHEN SUBMERSED IN GASOLINE. I SPENT MANY MONTHS WITH SUBMERSED SAMPLES IN GASOLINE, WATER (SOME EPOXIES DISSOLVE IN WATER WHEN SUBMERSED!), OIL, ETC. I FOUND ONLY ONE THAT WOULD WITHSTAND GAS, OIL, WATER, ETC. IT'S MADE BY SMOOTH-ON: AN INDUSTRIAL SUPPLIER. I'LL POST BOTH (STOCK & EPOXIED) FOR ALL TO SEE WHEN READY.

I ALSO MADE AN INTERESTING OBSERVATION AFTER JACK AT RACETRONIX EDUCATED ME AS TO IDEAL PUMP BREAK IN. I RAN THE WALBRO PUMPS SUBMERSED IN WD-40 FOR 24 HOURS @ 10vdc. THE INITIAL AMP DRAW VERSUS THE 'BROKEN-IN' AMP DRAW WAS SUBSTANTIAL. AS JACK SAID NOT SO MUCH AN ISSUE WITH C4's WHERE NEW PUMP IS IMMEDIATELY SUBMERSED IN FUEL BUT CAN BE AN ISSUE ON C5's WITH AN EMPTY 'BUCKET' ON START-UP. REGARDS GREG

Bruce

Just a word of cautions. If you are going to run dual 340M fuel pump. As graig is mentioned. The fuel pressure are so high and your factory or aftermarket fuel regulator will not be able to control lower fuel pressure. Will required the use of a larger external regulator. You also should use a fuel pump relay for the second pump. First hand experience here.


Bruce

BlowerWorks

Bruce - Excellent caveat when running dual in-parallel pumps. I completely forgot about that issue.

That's exactly why I like the two pump series set-up using the in-tank 340 feeding an in-line 392. It's perfect for most set-ups. Two pumps in series mainly increases available head without overloading stock regulator. Even so the flow at idle is still substanially more than stock regulator was designed for: what with the stock pump only flowing 50 or so gph and the 340 flowing 70 or so gph.

Additionally when using the 340 in series with the 392 the amp draw of each pump is about half that of when used as stand alones. Each pump in series is working a lot less hard than by itself, extending pump life substanially. Finally if you use the Racetronix C44 harness it now feeds both the in-tank and in-line pumps off one relay at optimal battery voltage. It is the perfect fuel pump set-up for most applications and not that expensive.

Regards to all following this thread - Greg

Bruce

Greg
For most SC/turbo combo. People should not get involve with the dual 340M fuel pump. Unless you are planning to make 800-1000+rwhp. The cost of doing dual fuel pump is cost, mainly is AN fittings and braided line, man they are freaking expensive and required to modify the rails to accept the external fuelpressure regulator. I spent close to $500 just for AN fittings and braided line and fuel filter, this is not include fuel pump and larger external regulator.

If your hp range from 550-700hp, a single 340M pump a long with a BAP or inline pump will be more sufficent


Bruce

qwiketz

bruce, doesn't aeromotive make an lt1 specific adjustable regulator or does this one require modification too?

Bruce

Originally, I run a 2nd fuel pump and a 2nd -06AN feed line to the rail and use a small aeromotive fuel pressure regulator (directly bolt to the factory location). With the twin fuel pump, the fuel flow and fuel pressure is just to much for the small FPR to handle. I could not get the pressure to drop below 85psi. This is not good because the injector will lock up with to much fuel pressure.

The solution? I bought a large aeromotive external regulator and install and the problem solved. The twin pump a long with the twin feed lines work well. I changed my fuel line again. This time, its still a twin pump but feed a single -10AN braided line(about the same size as your garden hose) and split to 2 -08AN and feed to the fuel rails.

below is the pic with small aeromotive FPR. stock line and -06AN braided line


here is shot with large aeromotive FPR


here is my new fuel system with 10AN feed and -08AN to the rails and
-06AN return. The Y there you see, it will go straight down to the fire wall, behind the motor. it cannot be in the pic that you see here because the line kinking as this shown.

mn_vette

That's really weird because I have a dual walbro setup that I ran with the stock line plus an extra 6an line. I hooked up the second pump to a switch and I would only see a small blip on the fuel pressure gauge when I would turn it on and then it would level back out again. And this was with a stock FPR.

Racetronix

The return line is the main problem if you are unable to turn the pressure down. Turbo Buick owners have the same problem so this is why the second pump is activated by a Hobbs switch. If the return line it is upgraded to a -6 Teflon then the problem usually is solved.

Dual in-tank systems are best considered when making upwards of 650-750FWHP*.
A single in-tank GSS340 with a Racetronix harness and pump booster can usually support apx. 600-700FWHP*
Considering that a pump booster (MSD / KB) can add $230+ to the picture some people opt for our DP system which is totally plug and play for $500.00 which will support much more HP.
(* BSFC and pressure dependant.)

-6 Teflon braided line is half the price of rubber braided line. Teflon line will outflow rubber line for the same given ID. Teflon line is resistant to today's gasoline cocktail where rubber line will dry and crack (this is why new fuel systems do not have rubber in them). -6 Teflon line flows enough to support upwards of 1000HP. -10 is overkill and adds much internal volume to the feed line. Thick lines were commonplace in oldschoool carb days where system pressures were in the 7PSI range but are not required at the same HP levels when operating fuel injection pressures.

Racetronix
sales@racetronix.com
C4 Fuel Pump Systems, C5 Fuel Pump Systems, High Impedance Injectors > 60# F/M, 57# F/M, 50# F/M, 42#, 37#, 32#, 28#, 32#, 24#
Please check our web page for low impedance flow-matched injectors from Siemens and Delphi ranging from 55-95lb/hr.

Bruce

Jack
can you tell me where can I buy teflon braided line for 1/2 of rubber braided line?? To what I see on Summit and Jegs catalogs, the teflon braided line cost way more than rubber braided line.
I don't know about any one else using a -06 teflon braided line for a 1000hp applications. Certainly -06 teflon braided line won't be on my 1000rwhp turbocharged 383LT1. That is why I am using a -10AN line.

Bruce

Racetronix

Aeroquip industrial braided Teflon line has the same spec as the automotive stuff for about half the price. The industrial stuff has a fine red strand running down the braid. Both lines use the same fittings.

Line size is only part of the equation. The frictional losses within the lines and the pumps ability to produce healthy volume at elevated pressures are just as important.

There is an old thread around here from about two years ago where I addressed this topic.

Racetronix
sales@racetronix.com
C4 Fuel Pump Systems, C5 Fuel Pump Systems, High Impedance Injectors > 60# F/M, 57# F/M, 50# F/M, 42#, 37#, 32#, 28#, 32#, 24#
Please check our web page for low impedance flow-matched injectors from Siemens and Delphi ranging from 55-95lb/hr.