NEW DW 400 IN-TANK PUMP!

[pacecarta]

This may not be exactly what you were asking for, but someone tested the pressure loss of the stock feed and return lines.
http://www.gnttype.org/techarea/fuelsystem/Returnlinearticle.html

i just read that and i have to disagree with nick
its not flawed ...its rubish ... i read nothing that was correct to the theory of operation and the way it actually works ... i lost IQ as i read along

 

[RobS]

i just read that and i have to disagree with nick
its not flawed ...its rubish ... i read nothing that was correct to the theory of operation and the way it actually works ... i lost IQ as i read along

I guess one mans rubbish is another mans treasure. Sorry everyone for the post.

 

[Nick Micale]

Rob, please do not take Paul's or my post personally, we were just pointing out the change in technology over the years. We did not mean to be harsh to you, just making a point about internet info, especially if it is out of date.

Many times we have had bad experiences and learned from them, but we want to pass on our "mistakes" so others do not have to experience them!

 

[pacecarta]

even though its wrong that article puts numbers to a problem that if your car was under construction you might not have been aware of but once your system is running you would see it .
problem is with increased flow (from larger pumps than stock) a base fuel pressure cant be set due to problems in the return system ..this can happen even with a walbro 255lph and hotwire

besides the base pressure you need to see the pressure pull down 1/2 of your vac reading from base at idle
if you have 18in/hg at idle you should see a 9psi drop from base FP with vac line connected at idle ...if you don't the return is too small for the incoming supply

with duals the fix is to activate the second pump later (this was done years ago with a hobbs )
if one larger pump is too much you need to clear restrictions (certain regulators have more restriction) . up size the return system is an easier fix

if you've up sized the feed line you can use the old OE feed lines to return to the tank and at 3/8" you should be fine with most single pumps
or you could run a second stock 3/8 feed line and use it for the return
even running the return through the OE vent line (change back at tank) will free up some restriction as the return is only 5/16 and the vent is 1/4"

 

[RobS]

Rob, please do not take Paul's or my post personally, we were just pointing out the change in technology over the years. We did not mean to be harsh to you, just making a point about internet info, especially if it is out of date.

Many times we have had bad experiences and learned from them, but we want to pass on our "mistakes" so others do not have to experience them!

Thank you Nick. I look foward to your results.

 

[RobS]

even though its wrong that article puts numbers to a problem that if your car was under construction you might not have been aware of but once your system is running you would see it .
problem is with increased flow (from larger pumps than stock) a base fuel pressure cant be set due to problems in the return system ..this can happen even with a walbro 255lph and hotwire

besides the base pressure you need to see the pressure pull down 1/2 of your vac reading from base at idle
if you have 18in/hg at idle you should see a 9psi drop from base FP with vac line connected at idle ...if you don't the return is too small for the incoming supply

What I found interesting was the return line is overwhelmed around 90 gph.

with duals the fix is to activate the second pump later (this was done years ago with a hobbs )
if one larger pump is too much you need to clear restrictions (certain regulators have more restriction) . up size the return system is an easier fix

I agree.

if you've up sized the feed line you can use the old OE feed lines to return to the tank and at 3/8" you should be fine with most single pumps
or you could run a second stock 3/8 feed line and use it for the return
even running the return through the OE vent line (change back at tank) will free up some restriction as the return is only 5/16 and the vent is 1/4"

Thank you for the suggestions.

 

[Ttype6]

This may not be exactly what you were asking for, but someone tested the pressure loss of the stock feed and return lines.
http://www.gnttype.org/techarea/fuelsystem/Returnlinearticle.html

This article talks about the problem that is created when we send too great a volume of fuel to the motor at an idle or during lower fuel needs of the motor (cruising). In this article he mentions how this happens when you run two pumps at the time. The same thing happens when you use one large pump. This is very old news that is just as true today because the laws of physics haven't changed from then to now. His solution is to turn the second pump on at a predetermined boost level with a Hobbs switch. You don't have this option when you run one big pump. You will have to modify or replace the return line to get the idle fuel pressure down to where it needs to be depending on how big the single pump is. If you persist in the propagation of this truth in this community,you will be met with violent opposition by some of the members here. If you're someone who doesn't wish to replace your return line,don't install a big pump that creates this problem. The stock feed line can easily support 1,000 hp on gasoline.

Everything in this article is true,however fullahotair is asking about how much pressure drop is in the fuel delivery side. The line itself creates about three lbs of pressure drop as it moves from the tank to the fuel rail. The filter is the most restrictive thing in the fuel delivery line. Depending on which filter you use the added pressure drop can be much more. I've found the AC Delco to be the least restrictive.

 

[fullahotair]

The line itself creates about three lbs of pressure drop as it moves from the tank to the fuel rail. The filter is the most restrictive thing in the fuel delivery line. Depending on which filter you use the added pressure drop can be much more. I've found the AC Delco to be the least restrictive.

at what flow?

To figure it all out, you need to install a pressure guage (or transducer) as close to the pump as possible, and one just before the regulator. You'll also need to know what flow you are sending through the line. This will tell you what the pressure is at the pump and what it is at the pressure regulator. The difference between the gauges will be the pressure loss at whatever flow you are pumping. If you do it for various flows you'll get a system curve.

But it really doesn't offer a lot of benefit at this point, as there are enough experienced people on here (like Nick Micale and many others) ...that know what works and what doesn't so going to the efforts to put exact numbers to it is a lot of work for little gain....my two cents anyway and thats not directed to anyone..... If its of concern to someone - then upgrade the line...but yeah i know its not a glamorous mod or upgrade like a new turbo or IC.

If someone tells me the exact inside dimension of the fuel line, i can model it at work and get a rough idea of friction loss per foot. It'll put you in the ball park anyway...

Nate

 

[84AireCaliente]

Nick, I am interested in seeing REAL world results from this pump.

 

[Ttype6]

If someone tells me the exact inside dimension of the fuel line, i can model it at work and get a rough idea of friction loss per foot.

Nate

The inside diameter of the feed line is approximately .300". The four Saginaw fittings in the feed line are much smaller. I can't remember the exact size,but I think it's in the .240" range. Red Armstrong sends gasoline to a 1,000 hp motor through the stock feed line with these restrictions. I drilled the four Saginaw fittings to .299" diameter in my supply line.

With two 255lph pumps turned on,the pressure loss will be about 3 psi from the tank to the rail with no fuel filter. About 7psi with an AC Delco filter installed. This is what happens while a 1,000 HP buick V6 is being fed gasoline. If you want the fuel rail to see 70 psi,the pump needs to make 77 psi.

 

[JDEstill]

I really hate to resurrect old threads... but I was doing a little research looking for some fuel pump info and came across this one. Lo and behold I see that this old article I wrote back in 1998 (actually it was originally an email to the old mailing list) was referenced, and in a negative manner. "its not flawed ...its rubish ... i read nothing that was correct to the theory of operation and the way it actually works ... i lost IQ as i read along" I think I have to take offense to that statement! I reread the article, and 17 years later it still looks good to me. Sure you can quibble over the actual numbers. Is the stock return line 1/4" instead of 5/16"? Maybe so. It doesn't change the conclusions. And, as noted, a lot of assumptions were made to generate the numbers presented. So sure, he numbers presented are in no way Gospel. But I got the theory wrong??? That's crap. Prove it. I will admit that my technical writing skills were weaker back then, so perhaps I didn't communicate everything effectively, but is what I wrote *wrong*? I would say B.S.

Some background - on the mailing list back in '98 the question was raised by Todd King (who did some really great, really interesting stuff back in the day) and Cal Hartline (I'm guessing you guys do remember him) about what the real root cause problem was when trying to maintain a stockish fuel pressure when running a double pumper. Why could you not run both pumps at idle and maintain the desired fuel pressure? Was the problem the regulator, in which case a bigger badder FP reg would let you run both pumps and still be able to set the FP at 45 psi? Or was it the return line? At the time we did not know for sure. The three of us swapped a bunch of emails, and I did the calcs and the flow testing of my KB regulator, and I showed that yes indeed the return line was the problem. And it allowed those guys to move forward knowing that replacing the return line with a larger size was the right answer to that problem, and they didn't need to go looking for some big bad regulator that would be a simpler fix. I then thought I would document that work and share it with the mailing list, and that a few guys would find it interesting and helpful. Presenting that conclusion and the reasoning behind it is all I really intended.

It's interesting that as you go past the bad mouthing in the above thread, that even though everything I said was "wrong", the advice given is:
"with duals the fix is to activate the second pump later (this was done years ago with a hobbs )" and
"up size the return system is an easier fix"
Which is pretty much exactly what I said in the article.

And despite what some might say, 20 years does not invalidate anything that was written. Are there new options that have been developed since then? I suppose so. Running 65 psi as a base pressure instead of 45 psi does sound like an option now that wasn't available then, both from an ease-of-tuning standpoint and having fuel pumps available that can put up enough flow at 95 psi when running 30 psi of boost. Doesn't invalidate the article. In fact the article shows why you'd have to run 65 psi base pressure and why you can't turn it down to 45.

Hope this alternate perspective helps some future researcher...

 

[Nick Micale]

This thread had lots of various and heated discussions and some good info, but in the past 3 years some new products, development and methods have pushed the fuel delivery system to even greater levels!

One example is a customer has run a GN into the 9's with one DW pump and an alky injection system. This was done with modified lines, good wiring and lots of voltage to the pump.

There are various voltage boosters and pump controllers that can provide increased voltage which will greatly increase fuel supply when desired and needed.

Another development is a billet hanger/sender which is a lot better flowing as the in-tank supply pipe and the fittings are larger internally and less restrictive than any unit.

We have used the new 450L pump which can also supply enough fuel for 600+ RWHP, or 9's in a modified GN.

Recent experience has shown the factory wiring in a 30 year old GN is very bad from the battery to the pump and back, and many owners even using a hot wire kit only are curing part of the electrical circuit.

Not only is the ground circuit is not completed properly, the wire, relay and connectors are not up to par, especially the crap pieces used in the stock-type sender unit.

Over the weekend a customer was having issues with his stock TR not having power at normal speeds and really sluggish even after a new fuel pump he had installed. Fuel pressure was well under 40 psi running, and not responding to adjustment as it did have an adjustable regulator.

I do not know how this damn car even ran as the voltage at the connector under the bumper was 4.3 volts? This is the second turbo car I have seen lately with under 5 volts, not unusual to see 9 volts on a stock car.

All the theoretical stuff, comments and opinions aside, I personally want real-world mods and testing to assure adequate fuel delivery.

 

[87GN_70GS]

An easy solution to run a single big pump with the stock lines and stay at 45 psi base is to use a hobbs switch and relay to cut in a voltage drop to the pump via a resistor (say 1/2 or 1 ohm, 50 watt) during low fuel needs, then switch in nominal pump voltage during boost.

 

[Pronto]

Interesting thread with good info from the 90s and now. Safe to say there are several ways to skin a cat (provide enough fuel for your combo). Seems to me the answer is what ever you feel comfortable with as long as you provide the fuel needed. Personally I feel more comfortable with extra head room with the fuel system. I went with a Racetronix 255 double pumper setup and AN8 and AN6 teflon lines. I will never use this setup to its maximum potential but I also know it will give all the fuel I need.