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Discussion Starter #1
ProMaster gasoline engine rating:

Max power = 280 HP at 6400 RPM (also 230 lb-ft torque at 6400 RPM)

Max torque = 260 lb-ft at 4175 RPM (also 207 HP at 4175 RPM)


Since "maximum torque" is at 4175 RPM, then it follows that torque MUST be lower (or at best equal) at engine speeds below 4175 RPM. Therefore:

Power at 3000 RPM can be no more than 148 HP

Power at 2500 RPM can be no more than 124 HP

Power at 2000 RPM can be no more than 99 HP


I hope the above shows why it is often necessary (perhaps too often for some tastes) for a ProMaster with gasoline V6 to use higher RPMs to get the job done. The above data should also show why up shifts at lower RPMs may not be possible or advantageous.

I know this may sound a little too technical for some, but I feel it's necessary to understand the basics of what this engine can and can not accomplish as RPMs start to drop. This is all based on RAM engine ratings for PM.
 

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thank you :D Its very easy to see when broken down this way.

How did you go about making the calculations? Its something I would like to be able to do on my own in the future...
 

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Discussion Starter #3
HP = (torque X RPM) / 5252


This is for horsepower, with torque measured in lb-ft. It's essential that units of measure are consistent with this equation. If we were to use torque in Newton-meters like many Europeans do, the results would be all wrong.
 

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Those are impressive numbers for a v6.
In everyday driving should be in the lower rpms but its there waiting for::
passing/Towing/roadrage/merging. What did I say roadrage? everyone should be
courtesy and love one-another. he he. There out there.
 

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ProMaster gasoline engine rating:

Max power = 280 HP at 6400 RPM (also 230 lb-ft torque at 6400 RPM)

Max torque = 260 lb-ft at 4175 RPM (also 207 HP at 4175 RPM)


Since "maximum torque" is at 4175 RPM, then it follows that torque MUST be lower (or at best equal) at engine speeds below 4175 RPM. Therefore:

Power at 3000 RPM can be no more than 148 HP

Power at 2500 RPM can be no more than 124 HP

Power at 2000 RPM can be no more than 99 HP


I hope the above shows why it is often necessary (perhaps too often for some tastes) for a ProMaster with gasoline V6 to use higher RPMs to get the job done. The above data should also show why up shifts at lower RPMs may not be possible or advantageous.

I know this may sound a little too technical for some, but I feel it's necessary to understand the basics of what this engine can and can not accomplish as RPMs start to drop. This is all based on RAM engine ratings for PM.
All horsepower/torque ratings are taken from the crankshaft on a dynamometer. Adding the transmission to that crankshaft is where all the magic happens.
 

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Discussion Starter #6
All horsepower/torque ratings are taken from the crankshaft on a dynamometer. Adding the transmission to that crankshaft is where all the magic happens.
I'm not sure what point you are trying to make. You'll have to elaborate a little more for me to respond. I don't want to guess at what you mean by "all the magic". Magic is not a technical term and is therefore too ambiguous.

By the way, I'm not discouraging disagreement. I just don't want to take your comment out of context.
 

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All overhead cam engines, which the 3.6 is, have to have more rpm to make horsepower & torque than a liked sized pushrod engine.
Most people buying these vans for work, are used to driving engines that are pushrod, and/or V8's.
I think that explains why so many are asking or are focused on these little V6's having to rev higher to get the power & fuel mileage
 

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Discussion Starter #8
It's interesting to note that new GM V8s in vans, which are pushrod, produce their maximum torque at a higher RPM than the overhead cam ProMaster's.

4.8L V8 295 lb-ft at 4600 RPM

5.3L V8 334 lb-ft at 4500 RPM

6.0L V8 373 lb-ft at 4400 RPM

However, relative to engine size, the ProMaster V6 produces more torque per liter of displacement. Also more HP per liter.


Ford E-Series engines, which are overhead cam but of older design, produce maximum torque at much lower RPM. They also produce less power and torque per liter of displacement than the PM V6. In this case lower RPM is not better.

My take is that newer engines breath better and can therefore get more power out of their size because they can spin faster. For its small displacement, the PM V6 is powerful.
 

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I would guess the PM engine is more efficient because of variable valve timing? Doesn't Ford and GM have that on their V-8's?

It's interesting to note that new GM V8s in vans, which are pushrod, produce their maximum torque at a higher RPM than the overhead cam ProMaster's.

4.8L V8 295 lb-ft at 4600 RPM

5.3L V8 334 lb-ft at 4500 RPM

6.0L V8 373 lb-ft at 4400 RPM

However, relative to engine size, the ProMaster V6 produces more torque per liter of displacement. Also more HP per liter.


Ford E-Series engines, which are overhead cam but of older design, produce maximum torque at much lower RPM. They also produce less power and torque per liter of displacement than the PM V6. In this case lower RPM is not better.

My take is that newer engines breath better and can therefore get more power out of their size because they can spin faster. For its small displacement, the PM V6 is powerful.
 

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The Pentastar engine has independent variable valve timing on both intake and exhaust, which is not all that commonplace. A lot of DOHC engines that have VVT have it on the intake cam only (e.g. the car that I have is like this - Mitsubishi).

It is very difficult to achieve this on a pushrod engine. The new GM pushrod engines do have VVT but the intake and exhaust are shifted simultaneously since it is the same camshaft that operates all of them and that limits the benefit. Also that is a 2-valve-per-cylinder engine. It does have the benefit of direct-injection.

I am not sure of it, but I don't think the Ford "mod motors" (4.6, 5.4, etc) have VVT and the truck engines are not using 4 valves per cylinder.

I know folks are worried about the transmissions downshifting easily with these, but it's not a problem, the engine can take it.
 

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I would guess the PM engine is more efficient because of variable valve timing? Doesn't Ford and GM have that on their V-8's?
The LS GM V8's, which are now only in the vans, I believe have VVT only on the intake side & do not have direct injection.
The new 2014 GM EcoTec V8's do have it on both sides as well as direct injection. I suspect we won't see the EcoTec's in the Express/Savana for a couple more years if ever.
The 3.6 in the PM doesn't have direct injection, but has VVT.

GM's 3.6 V6 puts out 305hp in it's base form, and 420hp and 430lb ft of torque in the 2014 Cadillac CTS (twin turbo)

Got a bit off topic there....
 

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All overhead cam engines, which the 3.6 is, have to have more rpm to make horsepower & torque than a liked sized pushrod engine.
Most people buying these vans for work, are used to driving engines that are pushrod, and/or V8's.
I think that explains why so many are asking or are focused on these little V6's having to rev higher to get the power & fuel mileage
Wrong

Where the cam is placed has little to do with the rpm at which it makes its power.

All big truck engines are OHC they make gobs of torque at low rpm.

The ford 3v 5.4 made power down lower than the pushrod counterparts when they were the current mills.
 

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Discussion Starter #14
I would guess the PM engine is more efficient because of variable valve timing? Doesn't Ford and GM have that on their V-8's?
I'm not certain, but think all Ford Econoline vans use the simpler and lower-cost 2-valve engines which I believe don't have VVT. Again, not certain of this.

What newest GM V6 and V8 engines do have is cylinder deactivation. I bring this up because it relates to the PM's downshifting issue that prompted this thread.

By using larger displacement, these GM engines can produce more power at lower RPMs, yet can save fuel when all power is not needed by deactivating half the engine. The PM, by comparison, often has to adjust to variable power demands by varying RPM. And the downside to this is that a transmission shift along with large RPM change is far more noticeable to driver than when a V8 drops off 4 cylinders.

Yet another approach to varying power demand while trying to save fuel is turbocharging -- like Ford is using with Eco-Boost. The engine can adjust (to a point) to varying power demand by more or less boost -- which the driver doesn't notice as much as the PM's shift and corresponding change in RPM.
 

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Discussion Starter #15
I wonder if anyone will develop a supercharger kit for it.
I read recently that Chrysler will have a turbo version of the V6 in the next year or two. They need it to compete with Ford and GM which already have turbo V6s.

Whether they will put one in PM is anyone's guess.
 

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I highly doubt such an engine would be put in something that is meant to be used as a workhorse. If Chrysler does a turbo Pentastar, it would likely be used in some version of the LD/LX cars (Challenger, 300C, etc), certainly a rear-drive application. Even then it opens the question of why they would do it, given that the premium engine in those cars is some version of the Hemi V8 ...
 

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Discussion Starter #17
I highly doubt such an engine would be put in something that is meant to be used as a workhorse. If Chrysler does a turbo Pentastar, it would likely be used in some version of the LD/LX cars (Challenger, 300C, etc), certainly a rear-drive application. Even then it opens the question of why they would do it, given that the premium engine in those cars is some version of the Hemi V8 ...
Competition?

Ford has already stated the new Transit will have the 3.5L Eco-Boost as an option. If turbos work for Ford Transit why not RAM PM?

Sourcing a FWD transmission that can handle the torque may be a challenge.
 

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Competition?

Ford has already stated the new Transit will have the 3.5L Eco-Boost as an option. If turbos work for Ford Transit why not RAM PM?

Sourcing a FWD transmission that can handle the torque may be a challenge.
thanks for the earlier response BTW.

I would think thats where the FIAT merger begins to show its magic. That or I heard the FWD 9 speed in KL cherokee and new 200 are competent.

On the diesel KL:

The engine produces an maximum peak output power of 140 PS (138 bhp - 103 kW) at 4000 rpm and a maximum torque of 350 Nm (258 lb.ft) at 1750-2500 rpm, and it is positioned in Front Transverse alignment in the Front Transverse of the vehicle.
could be an option...
 

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I bumped this old thread thinking it may help new owners better understand Pentastar gas engine behaviour. I still cringe at the sound of RPMs over 4000 even though I know it's OK. On our last trip, I had it on cruise control going up a mountain pass. It downshifted itself and hit 5000 RPM for a half minute or so. It took all my self control to let it be. But I still had to look all this up again when we got home: Max HP and redline are both 6400 RPM. It also maintains 90% of max torque between 1600 and 6400 RPM (max at 4175), which seems good for a gas engine.
 

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Yes, those numbers are pretty good for 3.6 liters or displacement.
Those RPM aren't that high either, for that displacement.
The smaller the engine and shorter the stroke, the faster it has to rev to make power. Think of how fast a mouse has to move it's little legs to cover the same ground at the same speed as an elephant.
I had a 600cc 4 cyl motorcycle that made all its power at 10,000 rpm, redlined at 16,000 rpm and tach went up to 20k.
Talk about cringing when the revs go up.
 
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