2nd Gen 5.0 v-8 underdrive pulley discussion thread

[Turdle]

OK
Think of riding a bike up a hill.
If you switch the front, or "crank" sprocket to a smaller one, it takes less effort to pedal your ass up the hill.

The crankshaft pulley will respond in the same manner, however other problems arise. The smaller pulley also turns the accessories at a slower rate.
To correct for this--a smaller water pump, and alternator pulley are needed, because the effective "belt surface speed" is reduced.
This leaves the idler, tensioner, A/C, and Power steering pumps spinning slower, which shouldn't be a problem.
Since the mass of 4 pulleys is being rotated slower--this should increase usable power to crankshaft.

How's that??

 

[jah81592]

My neighbor did have a charging issue with UD pulleys on his 90 5.0 Mustang. It was fixed by replacing the original alternator pulley.

You said the magic words-1990 Mustang GT. The early Mustangs had problems charging with stock pullies because they were handicapped by a low output alternator. Now enter the 1994 models and (3G which also is a common swap for early 5.0L Mustangs) alternators,charging problems gone. If I am not mistaken the 4G is on the 5.0L Ex but would have to look again to confirm this. I will repeat the late model stuff will not have problems with charging! I have been around Mustangs a long time, my immediate business has been core Mustang. I have had 7 Mustangs and 1 was TT'd and made well over 700hp. I am very familier with this setup. The v-6 soch use the 6G alternator and doesn't have problems at all with charging.Respectfully-James

 

[jah81592]

I don't want to make this a debate forum and I would believe that isn't what JT Smith wants either. The emphasis is only whether or not the 5.0L guys want me to work on this or not. I have a poll listed in the need for speed forum and JT is only supporting my move. The manufacturer I am dealing with is interested but will only make the part with enough support(purchase) from the public. I have stepped up to the base and said I will do what I can to make this happen. Only if you guys are willing to purchase.

 

[aldive]

The v-6 soch use the 6G alternator and doesn't have problems at all with charging.Respectfully-James

Mine did.

 

[chriswells78]

OK
Think of riding a bike up a hill.
If you switch the front, or "crank" sprocket to a smaller one, it takes less effort to pedal your ass up the hill.

The crankshaft pulley will respond in the same manner, however other problems arise. The smaller pulley also turns the accessories at a slower rate.
To correct for this--a smaller water pump, and alternator pulley are needed, because the effective "belt surface speed" is reduced.
This leaves the idler, tensioner, A/C, and Power steering pumps spinning slower, which shouldn't be a problem.
Since the mass of 4 pulleys is being rotated slower--this should increase usable power to crankshaft.

How's that??

Correct.

And in the same light, if you want to use the same belt, it has to be changed at the same ratio. To use Jon's bicycle analogy, the same chain fits when you change gears because of the small rate of circumfrance reduction and the tensioner. A smaller belt is not nescessary if you reduce one and enlarge another by the same or similar ratio.

 

[CougarX]

I am in assuming that they really do come out "competitively priced." As for the alternator issue, isn't the alternator on the SOHC the same as on the 5.0L? So we can just use the overdrive pulley that is available for the SHOC if we need to?

 

[aldive]

Yes, the alternator is the same and I see no reason why you couldn't use the same OD pulley.

 

[scruff]

OK I can see sense in all this, and see it as a valuable thing to have developed.
If you can give me a rough approximation of price and it's agreeable, I'll throw my hat in for one.

 

[chriswells78]

Personally, my ceiling would be $250, any higher than that, they wouldn't be worth it.

 

[jah81592]

The v-6 soch use the 6G alternator and doesn't have problems at all with charging.Respectfully-James

Mine did.

As far as charging problems, I stated in a previous post I don't have any problems. Well I don't. You will see your voltmeter read lower at an idle but any rpm will put back at full charge. Also even though the voltmeter is reading lower at an idle doesn't mean you are discharging. I have measured this. If you plan to overdrive the waterpump and alt with additional pulleys then your power gains will NOT be as great because you are focusing on overdriving two accessories which were previsously underdriven. So the total percentage you are underdriving will be less. I tow a trailer and haven't had any discharging problems yet. In the ECM software Ford has minimum requirements to be met before your battery light will come on and the ECM considers the battery discharging. I pulled 8 different boxcodes and here is what I found.


12.18-12.5V voltage_to_determine_charging_system_good
11.68-11.80V Voltage_to_determine_charging_system_bad

So obviously if your system is maintaining this voltage at idle without setting the battery light then you are not discharging. You are maintaining but not discharging. So therefore anything above an idle you will be charging. If you have a discharge problem with the single underdrive pulley then I would suspect a battery or alt. problem. I sit in rush hour traffic and the other day was sitting still for an hour because of a crash. It was raining and I have the blower going,heat strips in the rear window, 6pm definately dark,and windshield wipers no problems. Is it as good as it was stock? No, but stock has full charge at roughly just off an idle. The underdrive pulley is geared toward performance and they state the full charge for the V-6 Pulley is at 950RPM. No problems for me yet.Cheers-James

 

[Mtn8er]

Wow this is an interesting thread lol. If this set of underdrive pulleys increase power/torque and gas mileage and will not screw anything else up by throwing stuff out of wack and is a reasonable price, I'm all for it!

 

[jah81592]

Wow this is an interesting thread lol. If this set of underdrive pulleys increase power/torque and gas mileage and will not screw anything else up by throwing stuff out of wack and is a reasonable price, I'm all for it!

I would suspect that if the pulleys were produced that they would be priced competitively with other kits on the market that have a harmonic balancer for the main pulley and accessory pulley sets. Currently I don't see enough votes for me to be able to proceed with this. This is a huge R&D project and they will have to have the orders (demand) for them to engineer,design a set.

 

[scruff]

Thats a shame, are you just counting the replies to the survey or the ones in the thread too ?
What sort of number would you need ?

 

[chriswells78]

I think part of the problem is where the thread is located. I usually don't ever go to the need for speed section, I just happened to stumble on the thread via the home page. I think it might get more exposure in the modified 95-01 section where street and 4x4 ppl alike would be more inclined to see it.

 

[Turdle]

^ good point--I will move it now

 

[tktrain]

OK
Since the mass of 4 pulleys is being rotated slower--this should increase usable power to crankshaft.

Jon: I must respectfully disagree with you regarding the way the pulleys affect power. The reduction in the mass of the 4 pulleys in many cases would be negligible with respect to the rotating mass of the engine, transmission, and balance of the drive train. Besides, the crank pulley, for example, is typically steel on the OEM installation while the underdrive pulley will be billet aluminum. While the steel's mass is much higher than that of the aluminum, the amount of material present is typically much greater than in the OEM pulley, thus more than offsetting the savings due to the lighter material. Besides, the rotating mass would only be important when the engine is accelerating. It the old Newton's law thing about a body in motion stays in motion. Once it is turning at an RPM it would take essentially no more energy to keep the OEM pulley spinning vs. the underdrive pulley. There is a tiny gain from the friction of the items passing through the air they are in at a lower speed, but this would be very hard to measure.

The big differences are the parasitic drag created when the accessories are turned at a higher speed than they need to turn to get their job done. The water pump, in particular, will try to pump water at a higher flow rate if it is spun at a higher RPM. The same thing is essentially true with the alternator. There is also bearing friction, the alternator fan, and the cooling fan speed. All of these accessories are designed to do their jobs at a relatively low RPM and under a wide variety of conditions. The factory puts in a margin of safety to accommodate things like desert driving with a big trailer, stop and go city driving, poor maintenance, and bugs in the radiator. When we install underdrive pulleys on a vehicle we lower our margin of safety for these systems in the interest of getting less power robbed by them. Don't be surprised if you occasionally see marginal charging (with lots of extra power using stuff added to the vehicle) or the temp creep up a little higher than normal in extreme conditions when you switch to an underdrive system.

James: I'm definitely interested in pursuing this. Full speed ahead, brother, full speed ahead!

 

[MountaineerGreen]

^^ well explained.

Where I stand on this- I still use my truck for towing a trailer with electric brakes and I often have to idle in traffic with the AC running. Sure I could over drive a few of the things and under drive some of the others, but my gains would be marginal by doing so. It is an interesting idea, but at least for now, Im out. Maybe later when I don't have to tow, I can get a set.

 

[aldive]

Jon: I must respectfully disagree with you regarding the way the pulleys affect power. The reduction in the mass of the 4 pulleys in many cases would be negligible with respect to the rotating mass of the engine, transmission, and balance of the drive train. Besides, the crank pulley, for example, is typically steel on the OEM installation while the underdrive pulley will be billet aluminum. While the steel's mass is much higher than that of the aluminum, the amount of material present is typically much greater than in the OEM pulley, thus more than offsetting the savings due to the lighter material. Besides, the rotating mass would only be important when the engine is accelerating. It the old Newton's law thing about a body in motion stays in motion. Once it is turning at an RPM it would take essentially no more energy to keep the OEM pulley spinning vs. the underdrive pulley. There is a tiny gain from the friction of the items passing through the air they are in at a lower speed, but this would be very hard to measure.

The big differences are the parasitic drag created when the accessories are turned at a higher speed than they need to turn to get their job done. The water pump, in particular, will try to pump water at a higher flow rate if it is spun at a higher RPM. The same thing is essentially true with the alternator. There is also bearing friction, the alternator fan, and the cooling fan speed. All of these accessories are designed to do their jobs at a relatively low RPM and under a wide variety of conditions. The factory puts in a margin of safety to accommodate things like desert driving with a big trailer, stop and go city driving, poor maintenance, and bugs in the radiator. When we install underdrive pulleys on a vehicle we lower our margin of safety for these systems in the interest of getting less power robbed by them. Don't be surprised if you occasionally see marginal charging (with lots of extra power using stuff added to the vehicle) or the temp creep up a little higher than normal in extreme conditions when you switch to an underdrive system.

James: I'm definitely interested in pursuing this. Full speed ahead, brother, full speed ahead!

The ASP UD crank pulley/damper on the SOHC is steel and is no lighter than the stock one.

 

[aldive]

^^ well explained.

Where I stand on this- I still use my truck for towing a trailer with electric brakes and I often have to idle in traffic with the AC running. Sure I could over drive a few of the things and under drive some of the others, but my gains would be marginal by doing so. It is an interesting idea, but at least for now, Im out. Maybe later when I don't have to tow, I can get a set.

I have no problems whatsoever towing our Jeep on a tandem trailer with my SOHC with UD crank and UD water pump pulleys.

Here in Florida, the AC is on almost every day and has never been a problem.

A lot of the negatives about underdriving come from those who have not tried it.

 

[tktrain]

Aldive: A agree with your statements and those of James regarding the use of underdrives. The '79-'93 mustangs did have problems from time to time since they simply didn't have the margin-of-safety levels designed into them that the X's do.

I think the only time there may be an issue is when someone is towing a heavy load in extreme conditions and they have not been as meticulous in their maintenance as most of us here on the forums are. The average owner will most likely never have an issue of any kind.