Pumps in series or pumps in parallel

[Turbine Doc]

Doc,
Need a smart pencil I don't own one just OJT experience.

This sort of dovetails to an earlier post on fluid dynamics.

I know from gauge reading and performance loss, that with stock single fuel pump set up I run out of fuel delivey capability when pulling a 12K trailer, pressure in main filter bowl drops from 5 psi to 2 and max speed is 40-60 mph depending on size of hill. This also happens when running empty and punching it from 40 mph pressure drops off but truck stil accelerates okay. Temps all good, IAT 130F, boost at 12-14, rpm limited to 2000 rpm, egt 750-800 engine want's to do more but can't fuel it enough.

I'll be adding Racor filter soon and 2nd lift pump, question is do I need more GPM in a parrallel mode 2nd path to final filt or more PSI 2 pumps in series mode. Is this one of those trade off situations that I'll have to try either way and see which works best. Maybe parallel with a manual switch to energize in tow mode or perssure switch activated when fuel pressure drops below X psi, that way I don't over deliver when I don't need to.

What are your thoughts

[LanduytG]

Tim
I have had the R45s on my 6.5 before the OEM lift pump and have never had a problem. When I pull I gross out at about 15K. Can't tell you what the fuel pressure is though. Guess I need to add another gauge :D
Greg

[Turbine Doc]

Thanks Greg,

I just placed an order for a 660 R & (2) vacuum switches 1 I'll put on the 30 mic primary filt, and 2nd on the 5 mic stock filt bowl with LEDs to tell me when filt needs changing, probably all I'll need. I'm just concerned with press, vs. gpm relationship. In your opinion delivery with 2 stock GM pumps in series delivers what is needed in fuel demand safely without risk of over pressure, or foaming tank with higher pressure return??? My other concern is if pumps in parallel is return too much return when running while not towing, and again airiating the fuel in tank from return splash, hence the thought to have second pump activated by pressure switch or manual switch energized while towing.

I've followed details of fuel fiter in Dmax forum and after talking to Racor techs not sure some of the problems there are not from running too fine a media at high pressure once blocked. Racor would not give a recommendation one way or other; they did not want to be quoted ad saying okay to deviate from GM design, but did not think & <10 micron primary was a good idea, or series pumps on a plugged filter.

I was hoping Doc Lee could do some of his smart pencil calculations and give a generic opinion on fluid dynamics of PSI vs GPM.

As for gauges I'm with you there eyes bigger than my real estate to locate them, for the fuel pressure testing I'm running rubber hose from the bowl drain, thru the back of the hood, under the wiper, in the window, duct taped to the dash in pur MS Red neck fashon, it wurks but ain't purty looking. ;)

[tom.mcinerney]

In the TDP forum directory it suggests...."Ask Dr. Lee:
E-mail your questions for Dr. Lee to leeswanger@yahoo.com, and he will post selected questions and his answers here, for members only."

I suspect that if the Dr knew what you're up to he might respond; doubt he'd do calcs, tho!

[Turbine Doc]

Thanks Tom I just cut & pasted info in an email to the "Good Doctor", hopefully he is in and not out making house calls.

[CleviteKid]

Hey Tim,

I have been traveling around the country, but usually have my notebook 'puter with me to keep tabs on The Forum. One pump and one low-restriction filter ought to be enuf to feed 250 hp. with no problem, but if you need more, I would look into two pumps in parallel.

The only reason we care about pressure out of the lift pump(s) and to the fuel injection pump is that pressure is an indication that there is more than enough fuel being delivered to satisfy the Stanadyne's needs. We all know that trucks will run (although they may be hard to start, and stumble on hard acceleration) with a dead lift pump.

High power needs lots of fuel, measured in flow rate, like gallons per hour, or cubic centimeters per second, or grams per minute. To get more flow rate, you need a bigger pump, or more pumps. The check valves in the pumps will prevent one from back-flowing through the other one if they are plumbed in parallel. If you plumbed them in series, you might be able to MEASURE a higher pressure, at idle, but would not be able to flow any more fuel than just one would supply, at max flow rate.

Hope this helps confirm your decision.

Dr. Lee :cool:

PS: No-one needs to send a message to my email address to get a reply in this forum. Just post away -- if I have something to add I will jump in. If not, I will stand back and let the rest of you tackle the issue. ;)

[tom.mcinerney]

OK, Tim, moving forward...but you also have to read a post by 'gmctd'{10/16/2003 7:30 PM} to a topic initiated by 'slagona' in the 6.5L forum, "Holley Blue (or Red) for Fuel Lift Pump" {posted 10-16-2003 12:51 PM }.
The plan for the differential pressure switch is grand--it would've saved 'tex1'{Topic: Mr Goodwrench can't replace my fuel filter!, in Members forum } and his dealers' insurance companies over $10,000 , not to mention months of frustration. Good Luck.

[Turbine Doc]

Thanks all,

I will be going with parallel pumps and DP switches to read filter blockage I don't like arbitrary mileage change periodicity on filts, why change if they don't need it, or if I do need it before hitting the mileage periodicity I'd like to know that also.

Doc I'm not making 250 Hp yet :D I'm guessing 225 may go to Dallas dyno run next weekend and see just what mods so far are doing for me, long range though I'm hoping to go for 300 Hp mods.

With a heavy load 12K trailer I sure struggle up some of the bigger hills for want of fuel, all temps in the green, plenty of engine left to do the job 12 psi boost, 750 EGT just no increase in speed, topping at 40 mph, 1700rpm if I remember correctly.

Acting same as when I had restricted fuel filt, & corrected with new one, on lesser hills and flat land runs like raped ape up to 75mph if I wanted to run there. Running empty I can quite easily run to the GM limiter 98 mph :D with plenty of engine to spare.

Since I've decided to parallel pumps next question do I run a second line to the on engine filter body, or a single increased diameter one; this is just me brainstorming at the computer I've not popped the hood to think on either option. Oh last but not least, any thought on what diameter a larger single line should be.

[CleviteKid]

Hi Tim,

It has been about a month, how about an update? Have you done any of the mods discussed in this thread?

I should talk; I have been so busy with work that my backlog of truck mods is embarrasing.

Dr. Lee :cool:

[Turbine Doc]

No Doc got side tracked on it a bit they shipped me a gasser filt instead of a Diesel, then nobody in town had fittings, been working on my Deere 2020 and Ford 535 back-hoe as well; will post an update tho now that I know there is interest for it once I install it.

Changing direction, going to try series pumps first, as that will be easiest, then go parallel if not happy with that, just ordered a set of Hi-Pops from JK, want to make sure I have clean fuel at right delivery.

Went with 10 mic as primary, have 2 vac. switches 7" I'll mount at primary and factory filts, putting 12v LEDs on the gage pod to know when filts are dirty, and probably permanent gage for IP supply press instead of test rig gage.

"Honey do's" at the house in the week to have time off for weekend hunting trips also limit time to work the truck upgrades during the week, maybe if I'm not in the woods all week Thanksgiving I can get it done.

My numbers at the Dallas dyno meet weren't as well as hoped 150 RWHP and 296 torq. But have been told not to dispair Dynojets are tricky to get good numbers on.

[ 11-19-2003, 06:37 PM: Message edited by: tbogemirep ]

[Turbine Doc]

Getting there Doc,

Installed a set of JK-HP injectors this weekend as Emeril says "Bam kicked it up a notch", cured some other problems as well check 6.5 forum.

660R filter, vac. switch #1 and pump #1 installed up and running on 1 pump, have made provision for the second pump just pulling together hardware for it.

Here is where I'm at (1) 5/16" ID line to filter bowl, out of bowl to 5/16" ID tee pump 1 connected to 1 side of tee, 2nd side capped for now

Question; I have rethunked it again smile.gif , and am going parallel pumps, now do I plumb the outlet of pump 2 with another tee combined with pump 1 dischage into single factory on engine filter inlet;

Or do I try to mod the factory on engine bowl to have a second 5/16" inlet(least desireable as it means I'll have to unwire/unplumb it and there isn't a whole lot of room to work.

Is a single 5/16" ID line capable of handling 2 pumps into it, pressure isn't my concern, I'm trying to keep gpm delivery up, I think that is key when pulling a heavy load what do you think, I have plenty of delivery for go fast playing :D when running empty/not towing on a single pump, I may even put a toggle switch on 2nd pump for tow only mode or stby if pump 1 dies.

[CleviteKid]

Hi Tim,

Saw your truck in the Photo Contest Thread, and visited your Imagestation album, COOL !

Many people (like me, maybe) would like to know EXACTLY how you put the 6.5LTD turbo configuration next to the A/C in the Rounded Line body style truck. But that is for another day.

I think your one 5/16" line will handle the flow just fine. If your engine compartment fuel filter blows up, then you know you had too much pressure. But the electric pumps are limited as to the max pressure they can put out, and will just slow down the pumping if the system back pressure gets too high.

Back to my dilemma:

Turbo and everything that goes with: $3000
Ten sets of rear tires in next 2 years: $3000
Tire smoke from Miami to Montana: PRICELESS

Dr. Lee :cool:

[gmctd]

Dr Lee
I'll tell you how that A\C trick is done, if you'll tell me how to put that little red sentence at the bottom of my post, so as to jump to my Imagestation album. :cool:

[CleviteKid]

When you click on My Profile and go down to signature, just add some UBB code. Mine is

{URL=http://www.imagestation.com/album/?id=4289701427&code=6361415&mode=invite} Latest Info and Pics of my Truck! {/URL}

except that the real code uses square brackets [ ] in place of the curly brackets { }.

Cheers,

Dr. Lee http://www.handykult.de/plaudersmilies.de/user.gif

[gmctd]

Ah...cause, and effect!

You are indeed worthy of the computer guru icon just after your handle, Doctor.

And, as with our beloved 6.5 - reciprocation to follow, shortly. :cool:

[gmctd]

Reciprocation

First, you must needs repair to a local boneyard of choice.
Therein, amongst the varied and sundry goodies and playpurtys, should you espy an S10\S15 vehicle, '88 to '94 vintage, check out the A\C evaporator housing.

Of similar evaporator size and nearly correct angle to clear the turbine housing, a certain amount of grafting will be required, via pop-rivets and black hi-temp RTV, in re-angling the entire housing.
It mounts in the original location on the firewall.

Results are barely discernable, even to the inquiring eye.

The C\K trucks were equipped with molded epoxy\ fiberglass housings thru the first years, then a switch to molded thermoplastic housings in later ('86 up) years.

S-10\S-15 housings were also molded from those same materials.

I used the molded epoxy\fiberglass versions.

Close proximity to the 600deg (avg) turbine housing will require some manner of foil-over- fiberglass R-12 insulation.

Otherwise, the R-134 converted A\C system performs flawlessly.

Good luck in your endeavors, Mr Phelps.
This post will deteriorate within 15 minutes!
;)

[ 12-06-2003, 09:28 AM: Message edited by: gmctd ]

[Scooby]

I added a Dahl water separator with a 2 micron element to my 6.5 . Although I would have rather put it AFTER the factory 10 micron filter, for the sake of easier plumbing, and quick removal if I have to take it to the dealer (adding fuel filter voids warranty- 18k more left) I went ahead and put it before the factory filter. I have had no pressure/ flow related issues. It did however take a few minutes when I first put it on for the fuel to saturate the filter element and flow to the factory filter. No water in the bowl yet !!! 2K miles

[Turbine Doc]

Scooby,
I thought you might want to know according to Baldwin their filts for the 6.5 BF1201 (Baldwin) & WIX 33376 are 5 micron filters not quite 2 but better than 10.

[airtime]

Doc,
I had a post almost done, went back to another forum, then *! Gone! Here it is again,
I had mentioned that I thought that if you didn't have time that maybe somebody else may have an answer.

1- Is piston slap and oil consumption related to each other on the 8.1? Would you consider 2-3 quarts of oil usage normal within 5000 miles? My feelings are Yes and No respectively. (GM does)

2- Have you heard of the Allison shuttering between 2nd and 3rd (in t/h mode) and between 4th and 5th (out of t/h mode)? Have you heard of any shutter instances at all? Would this be a torque converter issue, since (now school me if I'm wrong) in t/h mode the tc is locked, and out of t/h mode, it locks going into 5th, correct? Or would this be a clutch pack problem? I can't remember off hand which clutch packs control which gears, but aren't c1 and c5 together, and c2 and c4 together, then c3, or am I out in left field? It's been to the shop 5 times in 36000 miles, nobody can find anything, one of those times to an authorized Allison dealer. I'm strapped right now, so the suncoast upgrade is out of the question at least until after the daughter is born in Feb. Any help would be app.

By the way, you guys (Tim, Jd, Tom) post some good reads, a "Step Above" I think.
AT-

[CleviteKid]

Thanx for the kind words, but I am close to ignorant on Duramax/Allison issues. The only Duramax I ever drove was at Rendezous III, and that was the Pikes Peak race truck with a 600 horsepower, 5000+ rpm Duramax.

HOWEVER . . . . . someone had set the parking brake and no one from GM could figure out how to unlock it, so it performed about like a Kia.

If you put this post in the Duramax Members Forum you should get some good answers.

Dr. Lee :cool:

[rjwest]

I was not satisified with ' cr*p in my filter so
I installed a second filter on frame rail ( perma cool) with a water drain. Truck ran fine except
on very hard pull ( pedal to metal ) i would get
very close to '0' fuel pressure at input to
injector pump. ( gage on dash) I put the filter on the suction side because the articles I read stated the water
seperator function works best with suction on filter.

I have since installed a second lift pump between
tank and 2nd filter. I only use it when pressure
drops very low ( rarely ).( Switch on Dash)

Also VERY handy for bleeding system after filter
changes....I do notice a teaspoon to several
tablespoons of water/rust from the secondary
filter.(Every Tank or two ) Also when I changed the secondary filter
it was quite black / primary ( oem )was very
clean, Note I do not drive much in VERY cold
weather so I do not worry about Fuel Gelling.

Fuel pressur will get up to 12-14 psi with both pumps running,no load, Usually 3-9 PSI normal running,. Hopes this helps.