I'm having a hard time understanding this. You see guys dyno their stock 5.7 vortec trucks and put down well over 200hp at the wheels, while you routinely see 5.9 magnums putting down measly numbers like 160 to the wheels. Having driven many examples of both trucks, the Chevys are way quicker. Generally the dodge trucks weigh a little more, but I drove a 5.7 suburban back to back with my 5.9 ram and even though they are very similar in weight, the Chevy was much much quicker....and my 5.9 is in great shape. No blown plenum or any of that nonsense. Solid compression on all cylinders, tuned up, etc. My truck even has 4.10 gearing and the 'burb had 3.73s.

I began my comparing specs on the engines, hoping to find something obvious...but I didn't find anything. They're very comparable.

Compression Ratio:
5.9 - 9.1 to 1
5.7 - 9.4 to 1
Negligible

Camshafts
5.9 - Duration @ .050 IN:189 EX:194 Valve lift with 1.6 Rockers (stock) IN:.439 EX:448
5.7 - Duration @ .50 IN:191 EX:196 Valve lift with 1.5 rockers (stock) IN: 414 EX: 442
Advantage Magnum (slight)

Cylinder Heads
See attached images



Advantage - Vortec

Intake Manifold
5.9 - 180CFM
5.7 - Unknown
Advantage - Unknown, but 180cfm should support up to 341 horsepower, so the intake in unlikely to be the bottleneck.


As you can see, the Vortec heads are better, but with the wimpy stock camshafts these engines run neither is maxing out the head anyway.

So what gives? Does anyone have any idea here? I know there are a lot of theories out there regarding "detuning" from Chrysler, but I have HPTuners, and I have personally observed my stock tune file. The timing is very aggressive, most certainly not neutered.

 

Tuning plays a big role in HP numbers as well. The GM units actually have a knock sensor, which the dodges do not, so, GM can routinely run at the very edge of spark knock, while the dodge has to remain much more mild on timing. There is a good bit of power lost there..... Also, the 700R4 trans has a pretty deep first gear... which gives another advantage in getting the GM rolling.

Also gotta remember, the 5.9's were only rated about 245 horsepower when they were brand spankin' new......

 

Nice theory, but the data doesn't agree with you.

Below you will find the stock spark tables for my 2001 Ram, and a 1998 Silverado 5.7 respectively. As you can see, the Dodge has much more aggressive spark tuning.



You are correct that the 4l60e transmissions have a lower (3.06) first gear than the 46re (2.45). However, that is likely more than made up for by the difference in rear gear. 4.10 in the Ram vs 3.73 or 3.55 in the GM. Also, the GM feels stronger everywhere, not just off the line.

Yes, 245hp rating for the 5.9, but only putting down 160-180 indicates they were probably overrated. The GM being rated at 250-255, and putting down 225 on a consistent basis.

 

For the GM, the tables are just a suggestion. The computer will adjust timing on the fly. That's the advantage of having the knock sensor. The tables are more of a failsafe, for times when it is running open loop, or limp mode.

What you see at the rear wheels depends on a lot on driveline efficiency. There can be anywhere from 10 to 30+ percent loss from the crank, to the tires.... That varies quite a bit even from one vehicle to the next, that are otherwise exactly the same.

Ramp profile of the cam makes a difference as well. While the absolute numbers may give the 5.9 a slight advantage, it would be interesting to see a graph. See how quick the valves open, how long they stay open, etc.

And then there is the whole 'difference in technologies' thing. Consider, 100 horsepower per liter used to be the holy grail of engine building. Today, we have production engines making 200 per liter.... (granted, high dollar sports cars.....) and getting better gas mileage while they are doing it. Heck, the base 4 cylinder engine in the camaro makes around 137 hp per liter...... A number simply unheard of not very many years ago.

 

I highly doubt that even if the GM ecu is correcting on top of that base table (and the dodge isn't) that it would run any more aggressive timing than the dodge is in the base table. 40 degrees is a lot of advance and it's there a lot of the time.

I agree on the driveline efficiency point. I wonder what the efficiency difference is between the 46re and the 4l60e, and between the GM 10 bolt and the Dodge 9.25". Tire sizes are similar, so that shouldn't change much.

Sure, ramp rates matter, but I highly doubt they are contributing significantly to this divide.

The 5.7 vortec and 5.9 magnum are very similar in terms of technology. Both are port injected, naturally aspirated, iron block, iron headed, V8 engines with very similar displacements.

 

There are several other tables in there that influence timing as well. The base numbers you see there are exactly that. Base. They will also be modified by coolant temp, intake air temp, etc, etc,.

Another thing to consider is manifold design. The kegger intake is never going to make huge power numbers. (well, unless you apply some variety of forced induction.... ) The runners in that think are LONG..... I think it was more than 20 inches...... (there is probably a spec somewhere talking about that....) The LT/LS intakes are pretty short runners in comparison.... I think it would be interesting to compare dyno charts that actually started down low... say, 1000 rpm, and see which engine is building more power in the range we actually USE our trucks..... Then setting that side by side with a chart showing vehicle speed vs. RPM in various gears.

Quite honestly, I think gm just has a better designed/more efficient intake track than the dodge, and that probably accounts for a good portion of the power difference.

 

This is honestly the only thing that makes much sense to me....but then again I look at Hughes dyno where they compare the kegger to the airgap, the m12b and m14b and the kegger is putting up the best numbers on most of the graph, coming in only a handful of numbers down from the rest on the big end.

 

Trouble is, their dyno charts don't even START until around 2500 RPM... Don't know about you, but, my engine rarely, if ever... gets to 3K..... The kegger pretty much blows away the others below around 3500 RPM... which is where a truck motor spends the majority of it's time.

 

This is a partially bunk argument. All dyno runs are done at WOT. No-one is driving around at WOT under 3000rpm. The trans just grabs a lower gear. It is probable (but not 100% certain) that the engine that performs better on the dyno at WOT will also make better part-throttle power than the lower performing engine.

That said, I agree with you, I am very rarely WOT in my truck. While I also agree that a long runner intake like the kegger is ideal for low RPM torque production, I still want to understand WHY these vortec chevies feel so much stronger. Even down low and even at part throttle....

I really wish light acceleration felt as effortless in my truck as it does in the Chevy, or in a modern Hemi for that matter. The 5.9 gets me around fine, but it just feels anemic for it's displacement. Everyone else agrees with this, which is why the 5.2/5.9 magnums have such a reputation for being dogs. Hell, I even remember driving my dad's 2wd 5.9 ram in high school and getting absolutely murdered by a bone stock 1994 silverado that was 4x4 (heavier) and only had a throttle body injected 350. It was pathetic.

 

We have two different topics going on here.

First one: Which intake is 'better', and why?

The m1 4bbl is a single plane manifold, so, yeah, it's gonna build power in the upper rpm range. The m2 2bbls I *think* is a dual-plane intake, so, it'll be better for mid-range, and a bit better in the upper rpm range. The kegger, on the other hand... is a LONG runner intake, specifically designed to produce bottom end torque. And it does a good job of it. Sure, dyno runs are done at WOT, however, even at smaller throttle openings, (everyday driving) the kegger is STILL gonna smoke the other two in bottom end, where in a truck, you spend 90% of your time. The hughes air-gap is also a dual-plan intake, so, it's is better in the mid to upper rpm range than the kegger. With a few supporting mods, you don't really notice the loss of low-rpm grunt, as you make up for it with other mods. So, in all reality, on a stock motor, the kegger is actually the better choice. M1 2bbl comes in second, and with a few other mods, is a great manifold, even for trucks. (ignoring that it is expensive..... ) The M1 4bbl simply doesn't belong on a street driven truck, that you actually do "truck stuff" with. (unless you do some other stuff, like cam, better heads, etc, so you get back the low to mid range torque the M1 simply isn't designed to produce.)

Second one: Why does the GM motor 'feel' more powerful?

Its all about efficiency. The GM engine is simply more efficient at producing power in the lower RPM range. That was the major idea behind the 'vortec' design. That, and the lower gearing in the trans, makes it feel even more powerful. No idea what the weight difference between GM, and Dodge trucks are..... I suspect the GM trucks are a bit lighter, and that helps as well. I believe that shedding 100 lbs, was worth around a tenth of a second in the quarter mile......

This is why I would dearly love to see dyno charts that start at a lower RPM. If I was building a race engine, where the engine is over 3K RPM almost all the time, then the current charts would be fine. But, I'm not build a race engine, and I really don't care about peak power. I care about how much power I am producing in the RPM range where my motor spends most of its time. Which simply doesn't show up on any of the dyno charts I have seen. I don't know if that is a limitation of the equipment, or simply something folks do, because no one really cares about the numbers down there.... they all want peak numbers....

Consider my V-10 engine. Those type of charts would be worthless to me, as my engine redlines at 4500 RPM....... I think I have actually gone over 3K twice, in the four years I have owned the truck..... The rest of the time, it's under 2500 RPM.

Ya also gotta remember, that the magnum engines were slight redesigns of the old LA engines. Engines that most of their development happened during the peak of the 'emissions' years..... Back when even a chevy 454 was only putting out a little over 240 hp in trucks...... (but, GOBS of torque..... ) I remember looking at those numbers, and scratching my head, wondering why in hades they had gimped those engines so badly. I mean, the guys on the street could double those numbers, without a whole lot of effort.... but then, they didn't have to deal with emissions requirements either..... (no testing around here.)

Back in the day, 100 horsepower per liter was the goal. Today, its the norm, for FACTORY engines, with a warranty. I mean, even six cylinders are doing 300 horsepower without effort, and are reliable for north of 200K miles....... There is a reason you don't see the magnum engines anymore. They are 'old tech', and simply can't compete with the newer stuff. The hemi makes more power, and gets better gas mileage... and the new computer controls and such, are only a part of that story.