GT Pump vs. Stock Fuel Pump & Alternator Tips

[Zack]

This may be trivial info, but I thought it was relevant to High Horsepower cars.

Before switching to the GT Pump, I watched my Duty Cycle on the ScanGauge. It was between 28-32 just cruising around.
After I switched to the GT Pump, the Duty Cycle dropped to 17-19 :eek:

I may be speaking Greek, but thats HUGE... in a good way! ;)

When you reach 100% Duty Cycle at WOT, your pump is maxed out.

Another thing I did in preparation of my Dyno Tune tomorrow is swap the clutched alternator pulley for a standard model. This will send 14+ Volts to the fuel pump at WOT vs. Battery Voltage only.
Part # for the pulley is: F5OY-10344-F from Ford. You will need a different alternator pulley nut which can be hard to find. I suggest a local electrical shop that rebuilds alternators. If you dont have the tool to get the clutched pulley off, use an air chisel to unthread it.....it works quite well..

Also.. you can bypass swapping the pulley altogether by tach welding the 2 piece clutched pulley together. Simply take the car to a welder, pop the cap on the pulley, tach it up and go! No more Voltage loss at WOT.

Hope this was helpful :beer:

[Joe Walsh]

The clutched alternator pulley is just a one-way clutch to prevent belt chirp due to overspinning of the pulley.

It works like a 10 speeds bicycle's rear hub...you can power it one way, but it free wheels the other way.

I've got the one-way clutched alternator and would NOT change it, nor weld it together.
If you run the alternator mounted backwards (like a Trilogy install) then you must replace the clutched pulley.

The charging at WOT function is handled by the computer.

BTW: Good update on the GT fuel pump. I've got to order one from Ray The Dealer soon.

[Zack]

The clutched alternator pulley is just a one-way clutch to prevent belt chirp due to overspinning of the pulley.

It works like a 10 speeds bicycle's rear hub...you can power it one way, but it free wheels the other way.

I've got the one-way clutched alternator and would NOT change it, nor weld it together.
If you run the alternator mounted backwards (like a Trilogy install) then you must replace the clutched pulley.

The charging at WOT function is handled by the computer.

BTW: Good update on the GT fuel pump. I've got to order one from Ray The Dealer soon.

Yes it is. As far as I know, the SCT software cant override it. I tried doing it in the software with no luck. Jerry W. Had to hook up his 'Black Box' back in 03 to override it.
I do know swapping pulleys remedies the problem.

Hey Trilogy guys, does your voltage drop at WOT?

[RoyLPita]

The Trilogy guys also have the tool that removes the clutch puuley from the alternator.

[DOOM]

Whats the price for the gt fuel pump?

[Zack]

Whats the price for the gt fuel pump?

About $90


Please discuss the alternator pulley in more detail.
If Im wrong about it, thats fine! Id rather get the straight scoop sooner than later.
:help:

[O's Fan Rich]

I have no voltage drop at WOT that I have noticed.
But then again I drive her like I'm an old lady.

[Zack]

http://www.mercurymarauder.net/forums/showthread.php?t=16262

I found this old post composed by you Joe :D

I can agree with the clutch and how it works, but if the clutch is freewheeling at WOT, that means the alternator is not spinning, regardless of the PCM controlling it or not.

Does that make sense?

[Breadfan]

http://www.mercurymarauder.net/forums/showthread.php?t=16262

I found this old post composed by you Joe :D

I can agree with the clutch and how it works, but if the clutch is freewheeling at WOT, that means the alternator is not spinning, regardless of the PCM controlling it or not.

Does that make sense?

Is the clutch just one way or is it electromagnetically controlled as well? If that were the case, the computer could "energize" the clutch on and off at will.

I'm only running 2 gauges at teh moment oil pressure and boost and no scanguage I cannot comment much, I suppose I could datalog the Xcal2 maybe that'd give some insight.

EDIT: NM I read the post that it's not electromagnetic but fully mechanical.

[Zack]

The clutch is mechanically driven only.

Here's my argument:

On a blower car, at the dragstrip or on the freeway...
If you go WOT for extended periods of time, that alternator clutch will be freewheeling the entire time.
That means that over the course of the WOT run, the actual 'guts' of the alternator will be slowing down or eventually stop altogether! Which ultimately leaves you with battery voltage and nothing more.

Im happy I switched to a regular pulley, I will adjust the tune so the PCM commands the alternator to make at least 13-13.5 volts at WOT.

[Breadfan]

If the only reason is for increased belt life and/or no chirping I'd say for a performance minded MM you'd be better off. I see your logic too on a S/C car getting a pump voltage drop at WOT could result in a less fuel flow when you need it.

I suppose this would be built into the tune since it would be tuned on WOT runs as well, but after several times or with a weak battery you could end up with low voltage/low flow.

If the clutched pulley is gone though, what advantage is there in stopping the alternator? If I read the link right, the computer just sort of shuts it off, so in theory even with a non-clutched pulley the PCM could turn off the alternator.

What sort of benefit would that be, without freewheeling it, you'd still need to turn the mass of the alternator just you wouldn't be getting any juice from it. Or is there less parasitic loss if it's not switched "on"?

[Paul T. Casey]

The clutched pulley adds to the "sinisterness" and "coolness" of the car. I like it when my lights go dim when I mash it. The premiss behind the design was to free up some extra RWHP at WOT. I'm not sure how much RWHP an alternator eats up, but hey, we're talking Ford Engineering here.

[FordNut]

Wow, it's amazing that this is coming up again.

The clutched pulley is a one-way clutch. It will let the alternator spin FASTER than the pulley but never spin SLOWER than the pulley.

The light dimming or output voltage dropping at WOT is controlled by the PCM and it works in a totally different way. It simply turns off the field voltage so the alternator doesn't put out any voltage even though it is still spinning. That takes the electromagnetic load and therefore the mechanical load off the alternator to free up a wee bit more horsepower.

The reason for changing the pulley for Trilogy cars is that the alternator spins the opposite direction and the one-way clutch would constantly slip, never producing output voltage from the alternator.

[Breadfan]

OK, so an energized alternator takes more effort to spin than an unenergized one, I was wondering where the hp gains would be if you're still physically turning the unit!

[Zack]

Im confused :bigcry:

[Breadfan]

Well now how exactly do you "turn off" an alternator? I can see turning off the current flow out of it, but how do you stop it from doing it's job, isn't an alternator just a type of generator? Therefore if it spins, it does it's thing.

So you shut down the electronics it will not output but the generator portion would still function b/c it's spinning. Does it use permanent magnets or electromagnets to generate current??

If I'm not confused I'm probably over thinking this and getting myself there.

[Krytin]

The software cuts field voltage to the alternator thus disabling any generation/output.
The one way clutch is just that - one way. As the motor slows down it will keep on spinning until the "generating" load on the alternator slows the rotor down to the driven speed by the belt. The clutch will pull against the rotor until there is a sudden deceleration on the motor/acc drive belt.
Hope that helps.

[2,4shofast]

What size pump is in the Marauder stock and how much HP is it good for? Should I upgrade my pump if Im just doing the typical bolt ons, no Forced Induction?

[Paul T. Casey]

Should I upgrade my pump if Im just doing the typical bolt ons, no Forced Induction?

No real need from what I can see. Stock fuel pump will supply stock sized injectors even with spacers and MAF upgrades. You'd run into problems if you went to 32 lb injectors.

[2,4shofast]

Awesome...thanks for the info!

[cyclopsram]

When your alt is charging, there is drag on it to make the electricity. I believe it is about 786 watts per HP. So P=IV
786 = 14.4I or about 54 amps per HP. So if your alt is charging full bore, it can eat up about 2 1/2 HP just to make the electricity. I may be all wet on this, but I seem to remember something from my schoolhousin of 40 years ago. The PIs have enhanced idle to keep the battery charged under heavy radio and light usage, keeps the idle from slowing down under heavy load. Sorta like when your AC clicks on and drags the idle down.

[ctrlraven]

Really interesting topic. Good info to know when going s/c, I would of never thought about the WOT alternator bypass affecting the fuel pump.

[FordNut]

Yes it is. As far as I know, the SCT software cant override it. I tried doing it in the software with no luck. Jerry W. Had to hook up his 'Black Box' back in 03 to override it.
I do know swapping pulleys remedies the problem.

Hey Trilogy guys, does your voltage drop at WOT?

There is a parameter to control it. I'll take a look at it and try to let you know what it is.

[FordNut]

Or is there less parasitic loss if it's not switched "on"?

That is true.

[Zack]

There is a parameter to control it. I'll take a look at it and try to let you know what it is.

I know where it is. I changed it and didnt notice a difference.

ill look at it again.

[RocsMerc]

Back When I was in high school physics, my teacher showed us a hand crank generator connected to an empty light bulb socket. He had us crank the generator with nothing connected and it didn't seem like anything special. I was able to spin it easily. Then he screwed in a 100 watt light bulb and told us to try to spin it again. It was alot harder this time. More than I expected. It took almost all my strength to turn that damn crank with enough speed to light the bulb when before the crank turned almost effortlessly.

[Zack]

This is all making sense now.
BUT...
There is no way the alternator will maintain sufficient speed to make voltage during a long WOT run.

Ill stick with the regular pulley and know I have consistent voltage driving my fuel pump.

[Joe Walsh]

This is all making sense now.
BUT...
There is no way the alternator will maintain sufficient speed to make voltage during a long WOT run.

Ill stick with the regular pulley and know I have consistent voltage driving my fuel pump.

The one way clutch does not disconnect the alternator pulley from the crank pulley/serpentine belt as the serpentine belt PULLS on it.
The alternator will always be pulled by the serpentine belt at least as fast as the crank is turning...
so at WOT your alternator is spinning just as fast as the crank.
There is NO loss of charging function. (Unless you reprogram the computer to shut down the field/charging current)

BUT,
When the engine shifts to the next gear and the crank suddenly slows from 6000+ rpm to 4500 rpm, the heavy alternator is still spinning at 6000+ rpm.
Suddenly the serpentine belt has now slowed to 4500 rpm. The alternator now wants to PUSH the belt faster than the belt will PULL it.
Hence the occasional 'chirp' from the belt on non-clutched alternators.
The one way clutch allows the alternator to overspeed the serpentine belt's speed until the alternator slows down to match the crank's/serpentine belt's speed.

[RocsMerc]

The one way clutch allows the alternator to overspeed the serpentine belt's speed until the alternator slows down to match the crank's/serpentine belt's speed.
It's only purpose is to extend belt life during sudden RPM drops. The alternator is never spinning slower than the belt. The clutch only lets the alternator spin faster than the belt. Therefore, no voltage loss is caused during WOT acceleration as a result of the clutched pulley.

[Marauderjack]

I wish the had a one way pulley for blowers......WOT = 60,000 RPM's at the impeller....1-2 shift has to play Hell with the drive belt and blower guts!!!:eek:

BTW...my understanding is exactly what Joe outlined.....the inertia from the alternator IS NOT transferred to the belt during shifts!!:beer:

I questioned Diablo on the rationale of turning the alternator off at WOT and they said assuming you have a good battery there will never be enough voltage drop during a 10-13 second blast to hurt anything.......I guess not as it has been working for me for over 2 years!!:bows:

My $ 0.02...FWIW??:confused:

Marauderjack:burnout:

[chader]

I suspect the tunner companies and the tunners(Lidio,DR,ect)would not have over looked something like this if it was a problem....jmho.I would bet their opinion would be backed with the best facts.

[Zack]

Alright, Ive done the research.

I compared a Stock tune against the Blower tune I have in the Blue car....
...the pcm is controlling the alternator in both tunes. ALL values associated with the alternator are the same.

Funny though, I went WOT with my un-clutched pulley this afternoon and voila! No Voltage Drop.

Case closed as far as Im concerned.
What do you think that noise is after a WOT run? Its the alternator clutch doing its job! Ever notice the voltage comes back up to normal when the sound diminishes?

Non-Clutched Pulleys.....FTMFW.....MF'er!

[Joe Walsh]

I wish the had a one way pulley for blowers......WOT = 60,000 RPM's at the impeller....1-2 shift has to play Hell with the drive belt and blower guts!!!:eek:

Marauderjack:burnout:


That is a heck of a good idea!
I wonder if any of the blower companies ever investigated a clutched blower pulley.

I guess that the blower's impeller has less weight-inertia than the alternator does, or they just count on belt slippage.

[Marauderjack]

I guess they count on the belt slipping Joe, but a 10K++ RPM drop with a J-Mod 1-2 shift can't be good on the blower or the belt....not to mention the tensioner and other components??:eek::shake:

Maybe Zack will come up with one someday??:beer:

Marauderjack:burnout:

PS: What I would like to see is a clutch like the A/C has so the blower doesn't run until you need it.....maybe just using a manual switch!!

[CRUZTAKER]

Hey Trilogy guys, does your voltage drop at WOT?

You swapped out my pump some time ago...thanks!

I know my voltage still drops, and here is an easy test for those still curious.

Get on the highway at night, preferably on a long stretch where street lights are spaced and limited. Zero traffic would be nice.;)

Cruising at say 45 or so, punch it and keep it floored until your balls run out.
Watch your dash lights and headlights dim as if your battery was low throught the WOT.

Mine does it MAJOR.
However, I rarely have too many accessories on under wot conditions. Usually nothing at all.

May I assume that what little hit of HP that is gained with the clutch under wot, is easily sacrificed for better fuel pump voltage once welded or removed?

[magindat]

PS: What I would like to see is a clutch like the A/C has so the blower doesn't run until you need it.....maybe just using a manual switch!!
Like Mad max in Road Warrior!

[Zack]

I wish the had a one way pulley for blowers......WOT = 60,000 RPM's at the impeller....1-2 shift has to play Hell with the drive belt and blower guts!!!:eek:

Marauderjack:burnout:

The big companies have them, but not available to the public.
They are used in the big events on the bigshot cars.

[sailsmen]

You swapped out my pump some time ago...thanks!

I know my voltage still drops, and here is an easy test for those still curious.

Get on the highway at night, preferably on a long stretch where street lights are spaced and limited. Zero traffic would be nice.;)

Cruising at say 45 or so, punch it and keep it floored until your balls run out.
Watch your dash lights and headlights dim as if your battery was low throught the WOT.

Mine does it MAJOR.
However, I rarely have too many accessories on under wot conditions. Usually nothing at all.

May I assume that what little hit of HP that is gained with the clutch under wot, is easily sacrificed for better fuel pump voltage once welded or removed?

I think it's controlled by the software and not a result of the oneway clutch which being one way only prevents the alt from spinning faster than the engine?

[Spectragod]

Alternator output on 03+ Panthers is controlled by the PCM.

SG

[Joe Walsh]

JEEZ!

How many times do we have to post this:

The one way clutch has NOTHING to do with shutting off the alternator at WOT!

Re-read this and many, many previous threads on this subject.

[Breadfan]

How would this scenario play out - you have a weak battery but haven't quite figured it out yet. It's on it's way out - in the next 1 or 2 starts it will not start the car cold.

As the driver I don't realize this, and romp on the car. Not just a quick romp, I stay on it for awhile.

My battery is weak and output voltage drops, and the alternator is not outputting anything to stablize it.

In this scenario, could I end up putting few too volts to the pump resulting in less fuel flow, cause a lean condition, and therefore a major problem?

I know it's kind of a wacky scenario, but could it go down like that?


PS. does the one way clutch have anything to do with shutting off the alternator at WOT?














PPS. j/k on that one, had too :D

[Raudermaster]

Like Mad max in Road Warrior!

Dreamland is nice!

[magindat]

Even in a low volt condition, the PCM will increase the pump's duty cycle will increase to keep the FRPS happy. The pump is PWM. It gets turned on-off-on-off very quickly. Duty cycle is the frequency (pulse) and duration (width) of that cycle. You'll only run into problems if you get to 100% duty cycle, are still dropping voltage and the pump can't keep up >>> LEAN. This is why you should never exceed 70% duty cycle on a pump. That 30% is the 'headroom' for the drop in voltage.

Now, on a low voltage condition during a healthy romp, you'll have OTHER problems. Most notably (at least in my experience with ricers that had distributors), you start losing spark and either not lighting the fire at all or not completely. Resulting in misfires and black smoke. You want full voltage for full spark.

Further, in our cars, my concern for low voltage would be all the sensors. They run on +5 input volts. If the car is down to 10.5, how low is that +5? Are all the sensors now report bad info? Low in ~ low out? Does the PCM correct for this when listening to all of the various sensors?

[Local Boy]

If I understand correctly, there is a stand by strategy (Failure mode) built into the EEC. This is designed to maintain vehical operation should one or more sensor inputs fail or is out of range. When a sensor input is seen by the EEC as being out of range (less than 5v) the memorized information stored in the EEC's Kam memory kicks in. Essentially, the EEC checks the sensors, in question, against it's records of normal readings during operating in the same conditions. If the EEC sees the senor inputs as being out of range, the EEC will replace the sensor readings with values from past memory. The ROM memory has a broad base of sensor readings (normal) permanently stored in the EEC.

If I'am correct, running with a low voltage (-5v) for a short time, will not cause the EEC to interpret the sensor readings as normal, and thus use a (KAM) back up memory of pre-established values...

Any thoughts???

ALOHA

[magindat]

If I understand correctly, there is a stand by strategy (Failure mode) built into the EEC. This is designed to maintain vehical operation should one or more sensor inputs fail or is out of range. When a sensor input is seen by the EEC as being out of range (less than 5v) the memorized information stored in the EEC's Kam memory kicks in. Essentially, the EEC checks the sensors, in question, against it's records of normal readings during operating in the same conditions. If the EEC sees the senor inputs as being out of range, the EEC will replace the sensor readings with values from past memory. The ROM memory has a broad base of sensor readings (normal) permanently stored in the EEC.

If I'am correct, running with a low voltage (-5v) for a short time, will not cause the EEC to interpret the sensor readings as normal, and thus use a (KAM) back up memory of pre-established values...

Any thoughts???

ALOHA

HOLY CRAP!!! You've been studying!!!!

I'll buy the substitute readings idea. Guess that would explain Kamikazee's problems is that he had been running low-volt so long, his backups were f-ed, too!

I still know for sure ANY coil based ignition will suffer from under voltage. The question becomes if there's enough head room voltage built in to the system to 'cover' such a condition. To boot, I'm sure we use up said buffer with forced induction!

[Local Boy]

LOL...:rofl::rofl::rofl:

Studying indeed, my friend...;)

That would be totally possible, particularly when you multiply the LEO accessories...and a car that already draws alot of power on a stock Alt....

In this case, the "Adaptive Strategy" function of our EEC's is not always positive...

Case in point: When we remove the battery connection to "clear a code" ...the EEC memorizes those sensor values as baseline and normal...So when we reconnect the battery...If it memorized a bad or out of range value as baseline...the light (code) will go away...

Now the situation is such were it will take the EEC longer to figure out that somethings is just not right...But it will...and the light (code) comes back...

You can see how this can work against us...

If I'm correct on this...

Thoughts?

ALOHA

[chader]

HOLY CRAP!!! You've been studying!!!!

I'll buy the substitute readings idea. Guess that would explain Kamikazee's problems is that he had been running low-volt so long, his backups were f-ed, too!

I still know for sure ANY coil based ignition will suffer from under voltage. The question becomes if there's enough head room voltage built in to the system to 'cover' such a condition. To boot, I'm sure we use up said buffer with forced induction!
In this situation with low voltage to the coils and say the fuel pump.They run off the same main power feed.Does anyone have any idea what kind of dtc's would be set?Possibly circut faults to the coils??I am getting these codes under WOT and have been suspect of the battery and or alt.

[Badger]

As far as I know the chip delivered with the Trilogy set-up disables the WOT alt field cut out. I haven't had a problem with voltatge drop on WOT.
If anything the voltage boosts to 14.1 as the alt field is on and more lines of flux are being cut.
Major difference between N/A and FI. One (N/A) you eek out every HP including underdriving the acessories. FI you want to support the blower and that includes all of the services associated with it.
There is enough headroom with FI that the measly 2HP drain from the alternator is not worth a brown out when running FI.