TFL Truck HD Dyno 2017 - RV-Dreams Community Forum

ahull · RV-Dreams Family Member

TFL Truck HD Dyno 2017

BiggarView · RV-Dreams Family Member

Interest data but I still maintain that to the "lay" truck driver, all three are a virtual dead heat. Only seconds of difference over the 7+miles of Ike Gauntlet is statistically irrelevant. To performance gear heads it's all the difference in the world to assert bragging rights. So you can get to the Wallyworld parking lot 30 seconds faster than the next guy.... knock your socks off. biggrin I'll be retired, who needs that stress?

JMHO, Brian

Bill and Linda · RV-Dreams Family Member

ahull wrote:
https://www.youtube.com/watch?v=emJcrYuJArg&t=0s
It looks like the TFL guys have the same questions. Here is the rear wheel dyno or power to the ground results & percent lower from engine dyno or manufacturer claimed numbers.
Ram: 338hp (12% lower) 828 lb-ft torque (8% lower)
Ford: 387hp (12% lower) 806 lb-ft torque (13% lower)
Chevy: 337hp (24% lower) 771 lb-ft torque (15% lower)
That is a 12% difference in horsepower and 7% difference in torque between them. So on this day the winner of the Ike produced the least hp & torque and the looser of the Ike produced the most horsepower.
If these numbers show the maximum rear wheel power that can be achieved IMO the Ike run is more of a demonstration of the engine mapping & gear ratio than it is ultimate power. Physics would show the Ford would win and the Chevy & Ram would be a dead heat .... almost the exact opposite of what happened.
Andy

Andy: That totally surprises me in some regards. I wonder - we have two different engine designs - two with smaller pistons - one with larger - same basic displacement - and we have three different transmissions and torque converters. It isn't going to happen, but I would love to see some engine block only testing to maybe determine where the losses really are.

I know "back in the day" most people who towed selected the manual transmission for the Ram (Dodge) because prior to 2013 (if memory serves) Dodge put a pretty weak 4 speed auto on the Cummins. In 2013 with the Ram they went to the Aisin trans and later with the HP version to the commercial heavy duty AS69RC transmission. This, IMO, changed totally the capabilities of the truck with the Cummins engine. But the point is, I wonder if the Aisin is the real difference in getting more of the rated flywheel power to the rear wheels? Also note the Chevy has smaller tires and a much higher ratio. Could that have anything to do with the tests on the dyno vs. the real world?

One other thought - most know with electronic throttle control one can't just "gun it" like before. The ECM is always watching all parameters and the "warranty police" at the OEM's have most likely limited what the engine can product under any given situation to keep stuff from breaking. While the engine on the dyno alone might be capable of the rated numbers, once it is installed in the truck another set of parameters comes into play.

Really doesn't matter much of a twit but interesting nonetheless.

Interested in your additional comments.

Bill

Cummins12V98 · RV-Dreams Family Member

I ran my 350hp 11 RAM on a Dyno in LasVegas and hit 304 I believe. I ran my 15 with 385 hp and hit 328 the other trucks were around 340, I let mine idle too long before running. Both trucks were on the same dyne. I don't think it really matters locked is locked on the trans. Gearing may make a difference?

ahull

We did the exact same percentage calculations. I posted this on RV.NET.

Percentage of advertised HP and TQ loss.

RAM
HP loss 12 percent
TQ loss 8

Ford
HP loss 12
TQ loss 13

GM
HP Loss 24
TQ loss 15

I ran my truck in LasVegas last May. I let my truck idle too long and had heat soak, I was told later. I hit 328 and the other similar trucks were at 340hp.

Can't wait til the 19 RAM comes out with their new emissions that are 100 percent down stream of the engine and are claiming 10 percent increase in HP and 20 percent increase in TQ just from the emissions getting off the engine.

RonC · RV-Dreams Family Member

I'm glad that Andy put up those results ... I was going to do so, but when I got here, found it was already done. I also found it interesting the "winner" had the lowest HP and Torque numbers of the three ... and that's real world at the drive wheels (not crankshaft HP and Torque which wouldn't allow for all the possible losses thru the torque converter, transmission, drive line and rear axle). While this test was done at altitude, they applied a correction factor to account for that plus temperature and humidity. All three trucks were tested on the same dyno, so the results are very credible IMO. Still make no sense that the lowest power truck was the fastest up the hill. The Ford made 50 more HP and 35 lbs ft more torque (at the rear wheels, so parasitic losses are accounted for) and was 15 seconds slower up the hill. Physics seems to have taken a day off. A real head scratcher.

-- Edited by RonC on Thursday 23rd of March 2017 10:33:06 AM

-- Edited by RonC on Thursday 23rd of March 2017 04:17:45 PM

ahull · RV-Dreams Family Member

Ok Bill my additional comments.

This is a bit of a head scratcher but I think I have found the reason why the Chevy, Ram, & Ford were near identical.

To start with, here is the specific data I put together to help understand. Someone mentioned the Chevy had small little tires (Bill?)....well the Ford has the smallest diameter tire and Ram is much bigger.

Truck	hp	rpm	torque	rpm	Tire Diameter (inches)	Final drive	2nd gear	3rd Gear	4th Gear
Ram	385	2800	900	1700	33.15	4.10	2.00	1.34	1.00
Ford	440	2800	925	1800	31.46	4.10	2.32	1.52	1.15
Chevy	445	2800	910	1600	31.81	3.73	1.81	1.41	1.00

Dyno Results Thoughts

The dyno results I don't think lie....those are real world tests all on the same day by a qualified company (i.e. this isn't a car show dyno test) and it appears to be the exact same trucks. Other than the Chevy these are pretty typical percent reductions 10-15% when comparing engine dyno vs rear wheel dyno. I also don't think the manufacturers are lying about engine dyno results.....they might adjust them in their favor but probably within a few percent on production engines.

HP vs. Torque

I don't want to get into an argument about HP vs. Torque but the Ike is all about horsepower and for that reason I am going to ignore torque. By definition torque is a force on a lever .... hang a 1 lb weight on a 1 foot bar and you will have 1 ft-lb of torque. Horsepower is the rate at which work is done. Work by definition can only happen when you apply a force and something moves. So common saying, torque gets you moving but horsepower keeps your speed.

Ram

The Cummins engine appears to have a redline around 3100 or 3200 rpm and it also makes peak horsepower at 2,800 rpm. This I think is the weakness of the Cummins. If you watch the video closely you will see the Ram once up to speed at 50 mph in 4th gear is below the peak horsepower. At some point in the run it downshifts into 3rd gear and probably hits near peak horsepower but then drops off. So in summary the Ram is almost always on the back side of the power curve and is not consistently putting peak horsepower to the ground. (Actually looks like the mapping is for peak torque)

40 mph rpm	Gear	50 mph rpm	Gear
2227.00	3rd	2078.00	4th

Ford

The Ford has a higher redline at ~4000 rpm and peak horsepower at 2,800 rpm which allows the engine to operate well above peak horsepower. Once at speed the Ford is in 4th gear and 60 mph and sometime later in the run the Ford shifts to 3rd. It would be interesting to know at what RPM it shifts and what the initial 3rd gear RPM is. Ideally it would be good to shift around 2600 and operate above & through peak power. My guess is the mapping for the Ford was not very aggressive and it waited to long to shift into 3rd. So in summary the Ford could probably stand to have a more aggressive mapping or to manual shift.

40 mph rpm	Gear	60 mph rpm	Gear
2662.00	3rd	3021.00	4th

Chevy

This is where I think it gets good. The Chevy has a redline near 3500 rpm and again it makes peak power at 2,800 rpm. Once the Chevy gets to speed it is going 46 mph in 2nd gear screaming at redline...it may have been in 3rd gear for awhile at the beginning but they don't show it. Interesting enough I think the 3.73 rear axle is a perfect match for this truck running up the Ike with this load. The Chevy didn’t appear to downshift and at the end of the run is at ~2,500 rpm. So in summary the Chevy was operating in the sweat spot of the horsepower curve for the full run without shifting.

40 mph rpm	Gear	46 mph rpm	Gear
2852.00	2nd	3280.00	2nd

Summary

BUT the Chevy did everything it could to get up the Ike and there is no reserve .... running full out in 2nd gear. Add a bit more weight puts you in 1st gear at the top which is not a good situation, this is where a higher rear axle ratio would help get you in a higher gear. The Ford & the Ram both appear to have a lot more reserve and could have run a lot closer to redline or with bigger loads.

Andy

-- Edited by ahull on Friday 24th of March 2017 12:05:58 AM

Bill and Linda · RV-Dreams Family Member

ahull wrote:
Ok Bill my additional comments.
To start with, here is the specific data I put together to help understand. Someone mentioned the Chevy had small little tires (Bill?)....well the Ford has the smallest diameter tire and Ram is much bigger.
-- Edited by ahull on Friday 24th of March 2017 12:05:58 AM

My bad - I was thinking F-450, not F-350.

Bill and Linda · RV-Dreams Family Member

ahull wrote:
Ok Bill my additional comments.
Ram
The Cummins engine appears to have a redline around 3100 or 3200 rpm and it also makes peak horsepower at 2,800 rpm. This I think is the weakness of the Cummins. If you watch the video closely you will see the Ram once up to speed at 50 mph in 4th gear is below the peak horsepower. At some point in the run it downshifts into 3rd gear and probably hits near peak horsepower but then drops off. So in summary the Ram is almost always on the back side of the power curve and is not consistently putting peak horsepower to the ground. (Actually looks like the mapping is for peak torque)
Andy

-- Edited by ahull on Friday 24th of March 2017 12:05:58 AM

Regarding engine mapping: The pickup version of the Ram (automatic transmission) -- torque peaks at ~1400 RPM and is flat to about 2,400 at which point torque drops off. Horsepower ramps up on pretty much as a straight line to about 2,400 right where torque peaks. HP drops off slightly with some variation to the red line of 3,200. At redline the HP is about 305 HP. (The commercial engine mapping is totally different BTW.) Torque and HP peak almost exact at the same place ~2,400 RPM. This is according to the charts sent me by the factory. Your red line number of ~3,200 is correct.

Bill

-- Edited by Bill and Linda on Saturday 25th of March 2017 11:13:02 AM

RonC · RV-Dreams Family Member

Thanks Andy ... very interesting (and thorough) posting. This clears it up ... I think