Thanks for sharing. I'm surprised; only 7% more HP and 10.5% more torque. I was thinking that maybe the 10 speed would have less friction to increase the spread.

 

Here is the graph on Five Star's site as well.

https://5startuning.com/wp-content/u...7.3-vs-6.2.jpg

 

I don’t know, I think it looks pretty good for what they were trying to achieve. Check out the monster low-end torque curve and how it compares against the smaller 6.2. It’s a significant upgrade, it should make a noticeable difference when pulling anything heavy. I think they were shooting more for longevity and durability than a peaky race car engine with mind-blowing numbers.

 

The 7.3 has 15% more displacement too.

I agree and very commendable on their part.

 

I would like to see a torque & HP curve with a 6.2 equipped with the 10 speed and 4.30 gears for a good comparison with both the 6.2 and 7.3 running in the 1 to 1 gear, the present 6 speed dosen't have a 1 to 1 gear.

All the dyno test are fine and give a good starting point but they still don't give a good handle on how it will pull a load over a long haul. The Eisenhower pull is fine but it still isn't a real life test for the average person pulling across country with many varying terrains. I did use the 5 Star results when I ordered my 2013 6.2 4.30 gears but I also took into consideration the 6 speed transmision over my 4 speed V10, my 2V V10 had more torque but less HP than the 6.2 but in real life because of the 6 speed the 6.2 is a better pulling combination.If something major happened to my 6.2 I would go with the 7.3 with 4.30 gears just because of the increase in HP and torque.
Denny

 

Pretty good gains over a modified 6.2 turning smaller tires on the dyno. I think a true apples to apples comparison would shed more light on the subject. What is shown is the 7.3 is stronger everywhere on the graph.

 

What I see is that it's very typical of what I expected. Given the 5-star data for both engines, they saw about 14% torque loss in the drive-train.

The 6.2L is rated 45 ft-lb below the 7.3L (430 vs 475). As you can see by the graph above, that's fairly consistent across the rpm range. It shows even a little less disparity than that at some portions of the rpm bands. The 7.3L also appears to either be limited in rpm or it just flat fell on it's face and they lifted off the throttle, because it starts to plunge at 5000 rpm where the 6.2L has more rpm to give. With the new 10-spd trans, all this really means is that the many trans gear selection choices will help make up for the slightly lower torque value in the smaller engine. If the 7.3L can pull "X" load up a 5% grade in 8th gear, that same load might make the 6.2L drop to 7th gear, and so on. That's about all it means. Big whoopie ... that's nothing to get excited about in my book. Yes - the 7.3L offers more grunt than the 6.2L across the rpm band (except at the top end where the 7.3L runs out of steam). But the new tranny is going to make up for that fairly easily; it will downshift one gear more behind the 6.2L and you'll be pulling the same load with the same ease.

As already discussed, had the "new" engine only been 6.2L of OHV, it would lose out to the SOHC. Or, if the SOHC 6.2L grew to a comparable 7.3L it would outperform the OHV. The more I read about it and think about it, this was pure and simple a gain for Ford in two areas:
- 7.3L engine is cheaper to produce due to less complexity
- 7.3L engine is smaller to package, making it more useful in more applications
This was never about power and torque. It's a cost and packaging move for Ford. Sure, the marketing department puts a great spin on it, but the real truth behind the scenes isn't that much to get excited about. Ford can get a little more pull from a cheaper engine to produce; that's a win-win. But it's not an over-the-top earth shattering improvement; it's just a good business move.

As long as the 7.3L earns a reputation as good as the old PSD 7.3L, it will be a winner because of reliability, not gross pulling power.

 

Very well said.

 

I wish they would have made it a damn 7.2, or a ford 7.4. now finding parts and info for the 7.3 is going to become more difficult

 

Just out of curiosity, why would that have anything to do with power output? I’m trying to wrap my head around a way valve timing or lift would care where the camshaft is mounted.

General Motors has been routinely making pushrod V-8s with higher power output then competing Ford OHC designs for decades now. Likewise the old lore of SOHC designs being peaky was disproven in 1991 with the advent of the modular V8 and it’s mammoth torque curve starting at 1500 RPMs. So if peaky pushrod engines exist, and stump-pulling OHC engines exist, what makes one better than the other from a performance standpoint?

 

I'll try to give some answer with the disclaimer there are exceptions to any generalization and there's no way to discuss the topic in its entirety.

The rpm range of an engine's power band is determined by several characteristics with the cam profile being perhaps the most important. Overhead cams provide the benefit of better valve train control at higher rpms...thus the "peaky" stereotype...which is good for a racing engine that needs top end horsepower. However, they can use a cam that makes its power at a lower rpm (typical for a pushrod engine) but then there's no point in using an overhead cam. Notable among the older engines is that the only way to shift the rpm range of any given engine's power band is to physically take the engine apart and modify it.

In the more recent years we've seen use of the variable time cam. This allows the cam timing to be computer adjusted on the fly which makes for a docile, streetable engine with mild idle characteristics and reasonable power down low while at the same time allowing for better top end horsepower. This (I believe) is why folks say the over head cam (i.e. 6.2) will beat a pushrod engine of equal displacement. It has good power down low (like the pushrod) but also has the ability to rev higher for top end horsepower.

The 7.3 (IMO) is right at home in a truck because higher rpms typically are not needed in a beast of burden. Long, steady pull wins the race....which by the way is why diesels excel in trucks but not in race cars.

 

5 star put a post up on his thread in the 2017 superduty forum. He gave a quick review of pulling their box trailer that is on an aluminum frame with their 7.3l tremor 4 30 geared truck. He said it was pulling it in 9th gear at 1926rpm at 66 mph and then downshifted to 7th on an overpass to maintain speed. Those 2 gears are very similar to 6th and 4th gears on the 6r100. Rpm wise I think the 6.2 and 7 3 will be pretty dang close pulling trailers. I asked what the weight of his trailer is but he never eluded to that fact. My 4.30 geared 6.2 pulls a 10k camper at these very same rpms. 6th gear on the flats and 5th or 4th on large overpasses. 3rd on good steep grades. In short i think the 7.3 will pull great. Just not lugging along at 2k rpm up hills like some may think it will. Some may be disappointed with their expectations. The real fun pulling will be utilizing those extra middle gears 2-6th. All those small steps will be nice pulling loads.

 

I used to think that way, but I imagine the engineers who designed the Cummins 15.2L ISX heavy truck engine would disagree. That's a large diesel engine that redlines at 2100 RPMs that's been using DOHC heads for 20 years now.

For years variable cam timing was only used in designs with overhead camshafts, but recent designs from General Motors and Ford have added that. From what I've read, the 7.3 L engine has a cam phaser that functions very similar to the units used on the 6.2L. The 6.2L has a single camshaft controlling intake and exhaust valves at each bank, so what advantage does that offer against a pushrod design that also uses a cam phaser on the camshaft controlling those same intake and exhaust valves?

Likewise, why would Ford have gone through the hassle of designing an overhead cam set up for the modular V-8s that never saw a VCT phaser for the first 15 years of their design life? The 2V SOHC designs were always stump pullers that run out of steam higher in the rpm range. The 5.4 L SOHC engine in my Expedition redlines at 5000 RPMs.

So with Ford's long-standing history of SOHC designs biased towards the low end of the rpm range, why would the SOHC design produce more power if everything else was equal? And with that, how come GM's pushrod designs have consistently made more power than Ford's SOHC designs of similar displacement?

 

I can't get into the heads of engineers but I will say that not all automotive decisions are engineering based. For instance, some designs are market driven to more or less give customers what they think they want.

 

Well said!