Underdrive Pulleys - Any Downside?

[Kvin C]

I've been enjoying the recent dyno/performance bolt-on threads of late - great info, so thanks to all.

 

I'm looking at some of these options for the Fall of this year so I'm taking notes and getting my ducks in a row.

 

In regard to underdrive pulleys (and of course specific to the SGT), has anyone experienced or heard of a downside to this installation? Charging problems, cooling problems, etc.?

 

Jer, I know you just went with Steedas; still happy with the change?

 

Kevin

[68fastback]

I've been enjoying the recent dyno/performance bolt-on threads of late - great info, so thanks to all.

 

I'm looking at some of these options for the Fall of this year so I'm taking notes and getting my ducks in a row.

 

In regard to underdrive pulleys (and of course specific to the SGT), has anyone experienced or heard of a downside to this installation? Charging problems, cooling problems, etc.?

 

Jer, I know you just went with Steedas; still happy with the change?

 

Kevin

 

The pulley sizes (which control accessory rpm) that the manufacturer selects are designed to assure that accessories (especially alternator and water pump) can keep up with load and still maintain the battery in a state of charge under realistic worst-case conditions: hot (A/C), evening (headlights/highs), in stop & go traffic at idle (slow engine speed), with high accessory use (stereo/nav on), etc.

 

Even with factory pulleys, charging is marginal under the worst case conditions but usualy sufficient (sometimes not). So, the downside to swapping pulleys is that you broaden the set of conditions under which the charging and cooling systems will be unable to keep up with load. Generally this is not a problem if you're aware of this and willing to lower the A/C or turn off the nav or reduce the stereo or hold the revs up occasionally while under those worst-case conditions. If not, you most certainly will run the battery down if the conditions exist long enough.

 

Most folks say they've never had a problem with pulley swaps because they either they just don't encounter worst-case conditions where/when they drive or just didn't notice the battery was being run down because the traffic/conditions (stop&go/idling, hot day, stereo-up, etc) changed/cleared-up before it was run down sufficiently to demand their attention. Also, if the water pump is run slower, overall cooling capacity is reduced proportionately ...at all rpm, so that should never be modified, imo.

 

I'm not a fan of pulley swaps (except on S/Cs <lol>) but many do it for a few easy extra ponies at higher revs (when accessory drag is highest) and if you don't encounter worst-case conditions the change to the manufacturer's design point won't likely be a problem.

 

Dan

[LuLu]

I had March UPDs on my three Marauders, and I didn't have any problems.

 

With the Marauder, both the altenator and the A/C shut off under WOT by means of an electrical clutch. There was a setting in the EEC software that would keep the altenator on in WOT and I changed this setting. Thus, no electrical problems. Moreover, I switched out the thermostat, from a 197 degree to a 180 degree, and I stayed with the recommended engine oil as well. Thus, no cooling problems.

 

I can't say this program would work today, it's four years later. I don't know how the SGT is set up, I haven't explored UDPs for LuLu yet. But, unless Ford changed their game plan, you should not have any problems.

 

UDPs should be good for single digit power gains, and every little bit helps.

[stump_breaker]

I'm not pro or anti UD pullies but if I had to choose, something going on over at the clubtitan site would sway me to the negative. These guys are buying a WRP underdrive pulley to replace the harmonic balancer and It would seem it's trashing the 2 piece flexplate due to vibrations. It would appear the pulley was not balanced correctly.

 

Now I say "it would seem" and "it would appear" because nobody has offered definitive proof that the WRP pulley is the culprit but the guys with the WRP pulley are the ones having the problem. And to be fair, some running the WRP UD pulley are not having a problem at all - yet. Also understand some of these guys are flinging a 5500lb truck down the 1/4 mile in high 13's and low 14's so there is a lot of stress on the stock components as is.

 

I personally will stay away from them because on the off chance some machinist was hungover that day and misses his tolerances, I still want an engine block a 1000 miles later.

[Cobramach1]

There's a lot of owners of the 4.6 32v engine who have now shy'ed away from the UD pulleys as well for a similar reason. In their case, the outcome is much worse because the smaller harmonic balancer is being blamed for the oil pump gears breaking at high rpm's. Needless to say when the oil pump goes south at high rpm's so does your engine. Again, it's hard to say if it's the UD pulleys, but it's only those guys that are having this problem and not everyone else. They're not worth the risk in my opinion unless the UD pulleys for the 5.4 are designed differently from the 4.6.

[LuLu]

The 4.6L is not internally balanced, and the damper (balancer, whatever you wish to call it) must stay on the crank. If you remove it, the crank snout will deviate out of round and crash the oil pump gears. I've seen quite a few shade tree wrenches remove the damper entirely, and suffer the expected outcome.

[Jer]

I've been enjoying the recent dyno/performance bolt-on threads of late - great info, so thanks to all.

 

I'm looking at some of these options for the Fall of this year so I'm taking notes and getting my ducks in a row.

 

In regard to underdrive pulleys (and of course specific to the SGT), has anyone experienced or heard of a downside to this installation? Charging problems, cooling problems, etc.?

 

Jer, I know you just went with Steedas; still happy with the change?

 

Kevin

 

Yup, delighted.

I haven't encountered the "worst case conditions" yet, but charging looks the same and A/C still blows just as cold, even in traffic the last three days (temp over 80 degrees) in bumper-to-bumper 1 hour+ traffic with the Shaker 1000 cranked. No dimming of lights with the bass drum, nothing...

 

BTW, I'm not just trying to be funny. This is an honest testimonial, as I've been watching for such things.

Dan's post is spot on, and I don't mean to minimize his warning.

 

No new vibrations, it's smooth as silk. Steeda advertises this as one of their "features", but I can't say that any brand difference exists. All I got were boatloads of recommendations for Steeda and March pullies. And my trusted shop is a Steeda dealer, so there ya have it!

 

Jer

[68fastback]

The 4.6L is not internally balanced, and the damper (balancer, whatever you wish to call it) must stay on the crank. If you remove it, the crank snout will deviate out of round and crash the oil pump gears. I've seen quite a few shade tree wrenches remove the damper entirely, and suffer the expected outcome.

I must disagree. ALL modulars are 100% internally balanced. That's why they all have is a harmonic damper and not a damper-balancer (like the SBFs do).

 

I agree that the damper cannot be removed and replaced with just a pulley -- that's suicide! The harmonic damper moderates the tortional flexing of the crank that results from the the connecting rods trying to twist it at rhythmic firing intervals, thus setting up harmonics at certain frequencies (rpm). Without a harmonic damper, the crank can easliy self-destruct.

 

There are two kinds of harmonic dampers: viscous interface and viscous filled. Most factory pieces are the former (not all -- the GT500 uses a viscous filled), most racing pieces are the latter. Not sure what type the 4.6 has but is definately only a harmonic damper, not an external balancer (which has an eccentric/crescent weight).

 

Dan

[myy2kgt]

Have had March UDP on for over 2 years now and no problems at all.

[hotrodbob]

Have had March UDP on for over 2 years now and no problems at all.

 

 

I have a set of Steeda that I put on about six months ago and have had no issues at all.

[LuLu]

I must disagree. ALL modulars are 100% internally balanced. That's why they all have is a harmonic damper and not a damper-balancer (like the SBFs do).

 

I agree that the damper cannot be removed and replaced with just a pulley -- that's suicide! The harmonic damper moderates the tortional flexing of the crank that results from the the connecting rods trying to twist it at rhythmic firing intervals, thus setting up harmonics at certain frequencies (rpm). Without a harmonic damper, the crank can easliy self-destruct.

 

There are two kinds of harmonic dampers: viscous interface and viscous filled. Most factory pieces are the former (not all -- the GT500 uses a viscous filled), most racing pieces are the latter. Not sure what type the 4.6 has but is definately only a harmonic damper, not an external balancer (which has an eccentric/crescent weight).

 

Dan

You're welcome to disagree, Dan, but production 4.6L engines in all flavors (-2V, -3V and -4V) have cast cranks (6 and 8 bolt) that are not internally balanced. That would be a special feature of a professionally built race engine. The OEM cast cranks are "neutral balance" and require an external balancer/damper to control vibration.

 

http://en.wikipedia.org/wiki/Harmonic_balancer

 

Damper or harmonic balancer, doesn't matter what you call it. You missed my point entirely, Dan, but you often do.

 

My point was that many others have misunderstood UDP install instructions from some aftermarket offerings and REMOVED the balancer. We do agree that would be a serious mistake, and that's all I'm trying to accomplish here. Get this message out to those considering this mod.

 

Thank you for your input.

[68fastback]

If it's just underdrive pulleys (e.g. larger alternator pulley to reduce drag), you likely won't have any problems (post#2 above), but if you are replacing your crankshaft damper (which also has a built-in pulley) with just a smaller pulley (no damper function) you *will* do damage either in the form of greatly accelerated bearing wear (crank and rod bearings) and/or premature and/or sudden flexplate and/or crank failure.

 

A proper crank damper which also incorporates a slightly smaller diameter pulley (to reduce drag) should not be much of a problem either (post#2) except that would affect all accessory loads (including water pump if driven off crank pulley) and is less desireable than just affecting he alternator, imo, because it reduces cooling.

 

A lower temp thermostat can *help* a bit but cannot increase the flow (thermal transfer capacity) reduced by rotating the pump slower with a different pulley.

 

Also, Ford ECU logic is such that no closed-loop sensor learning occurs until the water temp exceeds 182*F. So a 180* thermo will affect (limit or eliminate) ECU 'learning' as sensors age.

 

While it's true that under hard operating conditions (track/WOT-runs, etc) the temp will exceed 180 even with a 180* thermo, no sensor learning occurs under open-loop conditions (WOT, cold idle, etc) anyway, so just realize that with a 180* stat, you are limiting (reducing or eliminating) the ECU's ability to compensate for sensor aging over time which makes you prone to throwing codes and realted misdiagnoses much sooner than if 'learning' was occurring properly and your tune can therefore become suboptimized over time (the whole point of close-loop 'learning' is to prevent that).

 

Everyone's gotta make their own decisions and there are upsides and dowsides for every mod -- there is rarely a free lunch.

 

Dan

[68fastback]

You're welcome to disagree, Dan, but production 4.6L engines in all flavors (-2V, -3V and -4V) have cast cranks (6 and 8 bolt) that are not internally balanced. That would be a special feature of a professionally built race engine. The OEM cast cranks are "neutral balance" and require an external balancer/damper to control vibration.

 

http://en.wikipedia.org/wiki/Harmonic_balancer

 

Damper or harmonic balancer, doesn't matter what you call it. You missed my point entirely, Dan, but you often do.

 

My point was that many others have misunderstood UDP install instructions from some aftermarket offerings and REMOVED the balancer. We do agree that would be a serious mistake, and that's all I'm trying to accomplish here. Get this message out to those considering this mod.

 

Thank you for your input.

 

I didn't get it wrong, Mac. Don't feel bad, you're in good company with so many who confuse a harmonic damper with a crank balancer. The SBFs have (and require) both. The modulars have *only* a harmonic damper because they are 100% internally balanced.

 

If you don't believe me, crawl under your car and look at the back of the damper -- you will see no eccentric *ballance* weight to complete the balance of the rotating assembly(RA). If you look at a Small Block Ford(SBF) you will see the RA balancer integrated right in to the harmonic damper (two distinct functions), hence a harmonc damper-ballancer or harmonic balancer. That's why some meny get confused on this.

 

The distinction is critical tho. Even tho the modulars are internally balanced (a harmonic damper does not balance, it damps tortional oscillations) and have *only* a harmonic balancer, removing that function and substituting just a crank pulley is a very bad idea. That was my point.

 

My appologies if I offended in any way -- just want folks to understand how things *really* work.

 

Dan

[Reino]

[Cobramach1]

You're welcome to disagree, Dan, but production 4.6L engines in all flavors (-2V, -3V and -4V) have cast cranks (6 and 8 bolt) that are not internally balanced.

 

Actually, all 03/04 Cobra motor cranks are forged. All 03/04 Mach 1 manual tranny motor cranks are forged as well. 03/04 Mach 1 auto tranny cranks are cast. I can't speak for other 32v varieties though in older Cobras, or in Marauders or elsewhere.

[LuLu]

Actually, all 03/04 Cobra motor cranks are forged. All 03/04 Mach 1 manual tranny motor cranks are forged as well. 03/04 Mach 1 auto tranny cranks are cast. I can't speak for other 32v varieties though in older Cobras, or in Marauders or elsewhere.

Agreed, and this is exactly why I used the term "production" engine.

 

I do not view the 4.6L-4V supercharged '03-'04 Mustang SVT Cobra engine as a standard "production" engine that you will find in a gazillion "cousin" applications, such as taxi cabs, police cars, F-150s, Gran Marquis, Town Cars, Aviators, and so on.

 

The '03-'04 Mustang SVT Cobra has a hand built engine from SVT, not a "production" engine built under the InTech flag. This engine was available in only a specific automobile offered for a limited time, a "niche" car. Design-wise, it's a "cousin" perhaps, but twice removed?

 

"Eight bolt" forged steel cranks have eight crankshaft counter-weight lobes inside. "Six bolt" cranks have only six lobes inside, two counter-weight lobes are removed from the center of the cast crank.

 

The difference in counter-weights and balance is made up by what the crank snout wears, and the SGT has the heaviest of "what ever you want to call it" in dampers/harmonic balancers. BTW, when speaking of modular engines, Ford doesn't call it a damper, or, a harmonic balancer any more. It's just a crank pulley today. Wikipedia seems to agree with this technical homogenization, which is why I posted a link to that 411. Go figure? Dicing up the terminology seems a useless exercise, the end result is what counts.

 

The SGT has a production...err, ummm..."common" 4.6L-?V short block. Nothing special about it, surely nothing special about short block construction, or, design. It is not internally balanced, but I suppose at this point that we will never see any agreement on this.

 

Nonetheless...JAPLE...Just another production line engine. Guess it doesn't matter if the crank pulley weighs 10 pounds, or, not, and who really cares?

 

Just don't take off (what ever you want to call it) in a UDP install. That would make you very sad down the road.

 

Pizza is here, gotta go...Later, gents.

[Kvin C]

Hey, thanks to all for the thoughtful and varied input on the UDPs; much appreciated.

 

Kevin

[JeffIsHereToo]

So why if these are so good don't the car companies use them with some engineering work to compensate elsewhere? I keep thinking for a daily driver there must be some downside or wouldn't Ford just do this?

[LuLu]

So why if these are so good don't the car companies use them with some engineering work to compensate elsewhere? I keep thinking for a daily driver there must be some downside or wouldn't Ford just do this?

In retrospect, Jeff, Ford has done quite a bit of engineering on crank pulleys. The 4.6L short block has worn half a dozen different crank pulleys over the years. They vary in weight, diameter and number of ribs, and change depending on application. Auto tranny or manual would be one of the considerations in selecting a crank pulley. Moreover, Ford has to be concerned with longevity across a wide spectrum of automotive applications, and I would expect Ford to be conservative. Their goals are not to produce the most HP, but deliver MPG and address NHV issues.

 

Another element to consider, is the aftermarket, which survives by feeding us mods. If the SGT 4.6L-3V produces 319 brake HP, and someone in the aftermarket finds a way to bump it up to 325 brake HP, many of us will buy it. This doesn't always mean the mod is valuable, or, safe. It takes long-term field use to achieve validity.

 

There have been "bad" UPD designs and poor marketing. Back when the Mercury Marauder rolled out, there was a UPD design (I forget the trade name now) with misprinted install instructions, and the end result was blown engines due to damaged oil pump gears. Ford ate a few of the early failures, but there came a day they did not. At first, it was believed that the factory oil pump gears were defective, but once the poorly designed and incorrectly installed UDPs came to light, the door was closed.

 

No matter how well you make something, someone will try to make it better.