Just a quick one.....does anyone use in line pumps at all, with surge tank??

Is this do-able on the C4???

Or, I was loking at the racetronix/walbro 255lph pump, is there a better option out there?



Joe.

 

I use a holly high volume inline fuel pump

 

These pumps look very similar from manufacturer to manufacturer. I suspect the same maker makes them for a number of different suppliers, but even ones that look alike seem to work differently: Maybe different specs from the same builder. .I had a Bosch pump on one of my old cars, and it was unacceptably noisy when mounted to the back frame rail. I switched it for a Motor Craft in-line pump for a 351 powered f250, which looked the same, and installed it along with a surge tank under the hood, and the noise factor disappeared, plus the fuel flow evened out. The Motor Craft pump looked the same as the Bosch, but it was quieter,(at least it sounds quieter uner the hood), and cost almost half what the Bosch pump did.

 

how do you change the set up in tank to run the in line pumps??

Thanks. Joe.

 

Heck you could leave your old fuel pump in. Just disconnect the power to it. I ran new fuel lines and used the existing pick up.

 

If you use a surge tank, you must fill it with a pump of some kind ahead of the high pressure pump. In my case, I went back to the mechanical pump to fill the surge tank, and the high pressure pump is between the surge tank and the fuel regulator. The over flow then returns to a "T" that lets the first returned fuel re-enterl the surge tank, and overflow from there goes back to the fuel tank. I don;t know if you could fill a surge tank with a high pressure in-tank pump. The surge tank on my car is not a high pressure affair. I would probably want to put a low pressure pump in the tank, and fill the surge tank with it, and pump form the surge tank to the high pressure regulator. I went this route since I was getting a lean condition when fuel sloshed away from the pick up under cornering and acceleration. What year is your Vette? What kind of induction and EFI does it have stock, and what have you done to it? Are you modifying it to have more horsepower, thereby requiring a larger volume of fuel? Are you experienceing problems with the set-up you have?

 

Dartvader, I am having a small problem with hard cornering when the tank is lowish, it is not dead empty - quite- but i just dont think it should be happening. I am also going to do some top end work on it for some more *****, so i want a good, in-line preferably, set up with surge tank, which i would like to mount in the 'trunk' area. can i use an in-line bosch type, and use the standard pump to feed the surge tank??? My vette is an 84, standard fuel pump (these are low pressure are they not? so can that feed the surge tank?), k&n, 2.5in. exhaust, chip and thats about all, for now!!!

Joe.

 

Not required on a C4. Contact Greg@Blowerworks as he has the C4 fuel system down like a science. He also stocks Racetronix FP kits as well as our new in-line adapter harness for adding an in-line pump to the primary HW harness and pump kit.

http://www.blowerworks.net/

Greg has an excellent post with flow-test results for single, single modified, dual and in-line pump combo's with graphs. For some reason the search engine does not bring it up anymore. Perhaps he can re-post the data. A single in-tank system + in-line pump supports very high HP w/o pressure drop-off.

 

thanks for the link racetronix. if you can recall i sent you some e-mails wanting postage prices to Australia?!


I was just looking at the best options for the fuel system, I would really like to use a surge tank so i need t know.... can i use the std C4 pump to feed??

Thanks Joe.

 

i would also like to know.... does the 84 CFI system regulate its own pressure?? so can i use a higher pressure EFI pump without buggering up my injectors?? i did hear somewhere that the left hand injection units on the 84 models did all of the pressure regulating, so you could use pump that put out like 40-50psi.

Joe

 

First thing is I want to separate the '84 throttle body questions to another thread I'll try to get to later.

Second thing is to address the use of a 'surge tank'. Generally speaking a 'surge tank' is used to store fuel for consistent delivery under high 'G' forces from acceleration be it lateral or just plain drag racing. They've come into use on the C5's because the 'bucket' pick-up cannot replenish itself fast enough on big HP engines, nothing to do with 'G' forces - they simply run out of fuel even on a dyno with no 'G' forces present.

On the C4 the use of a surge really should not be necessary. The fuel tank in essence is a giant surge tank. If you are starving for fuel under hard cornerning you might check to see if the plastic tray at the bottom of the tank is in place. I've seen them come loose. If in place and you are still starving under hard cornering you must be really low on fuel and I don't see where a remote surge tank will buy you much time. I'd consider modifying the plastic in-tank tray and/or making sure the fuel pump pick up strainer is properly placed. Perhaps someone replaced the pump incorrectly at some time in the past. That said let's move on to fuel pump comparisons: both in-line and parallel.

First & foremost the stock GM fuel pump is questionable at best for any modified engine. With or without engine modifications I'd replace the GM pump with the high output Walbro GSS-340M. It's an even easier job if you go with the Racetronix kit because it includes many parts that are not included with a straight out pump purchase not the least of which is a new in-tank wiring harness with heavy duty wiring. Fuel pumps are extremely sensitive to voltage drop at the head. Even a seemingly small drop can result in a serious loss of flow as will be seen by the accompanying Excel graphs. Finally, for $69.99 add the Racetronix external fuel pump wiring harness. This harness, on any pump including your stock GM pump, will result in at least a 10% fuel flow increase.

Adding an in-line fuel pump to your C4 is probably one of the easiest mods you'll ever make. It's a very simple addition, especially if you've added the Racetronix external fuel pump wiring harness. The in-line pump mounts directly behind the rear license plate and can be done in less than an hour given the Racetronix harness is already in place.

Whether or not to add an in-line fuel pump to your C4 depends mostly on the desired peak fuel rail pressure. If you require fuel rail pressures of 55 psig or higher, install the in-line pump. The higher the fuel rail pressure the more desireable becomes two pumps in series. A Walbro in-tank GSS-340M feeding a Walbro GSL-392 can easily support 1000 HP thru the existing 3/8" id stock GM fuel line. This same set-up can easily support 1500 HP with a Kenne Bell BAP thru the same GM 3/8" id fuel line. A nice benefit from having two pumps in series is that the total amperage drawn is no more than a single in-tank pump working hard. Consequently the work done by each pump is shared and each pump runs at about half its' peak current.

Finally, if you're running around 55 to 60 psig and for whatever reason do not want the second in-line pump then epoxy close the pump's relief valve. This will eliminate the radical flow drop at 60 psig. Two caveats' here. You cannot use just any epoxy (some dissolve in gasoline) and second you have the potential to develop in excess of 100 psig if for some reason your regulator fails or the return line becomes inoperative.

The attached Excel graphs should be of interest to all making 'serious' HP. Regards Greg

 

thaks blowerworks. that was very helpful. a coupleof things for clarification sake... can a walbro GSS342 be used instead of the GSS340M???

And can the secnd inline pump be run with sandard pump?

could the second in-line pump to be wired to turn straight on with the ignition?? or with using the standard wiring for the standard pump, assuming for some reason i didnt go with the racetronix set up??

Cheere.

 

Would you run the inline off the BAP and the intank off 13.5v?

 

If you buy the HO BAP you can run both at the same time at higher voltage.

 

what is BAP?????

 

KenneBell and MSD make a voltage booster (Boost-a-pump...BAP) that ramps the voltage from 13.5v to 17ishV under controlled conditions. This increases the pump volume.

Never thought about running both pumps that way. Thanks Racetronic.