Little engines that can: Big power from small displacements

[GoldDog44]

I’ve been pulling 63,500 between AB and QC for 10 years with various engines and drivetrains. I do a fair amount of 48,000 into the US as well between ND, SD, MT, NB and WY but mostly ND lately. My choice to buy the CHU613 with the MP8 last year was from collective experience with company trucks since the emissions mandate kicked in. Also my preference in driving comfort. Although the MP8 doesn’t give that exhilarating 350 R600 goosebumpy driving experience, it is a formidable competitor in the super B segment. Yes, you can delete and tune a Cummins or a Cat and blow my doors off, but in stock emissions restricted form it puts more power to the ground than a similarly spec’d Cummins, Detroit or Maxxforce in stock form. Also creaming a deleted 600hp Cummins and running neck to neck with 750hp Bully Dog tuned C15 Cat with fuel economy. 

In terms of reliability, the MP8’s have had a consistently better track record than the ISX 15 Cummins. The company has deleted a number of Cummins already but the statistics never improved. 

We run all Mack and KW because they seem to be the only 2 that can take the punishment that is dished out by the demands of the grain industry and the ever swinging batwing doors of newly graduated drivers that can’t decide on an occupation. In 2017 we marked the end of Cummins and started with Paccar engines and so far they pull well and fuel economy is very close to the MP8. 

When I bought my truck it had to be a genuine Gold Dog Pedigreed Drive train. I found it in Calgary as the flat prairies for some reason haven’t discovered them yet but it was a 455hp. Mack approved the transition to 505 hp and 1860 tq but the ECM was too old for the newer program so I settled for 1760 tq. The truck had originally been spec’d heavy enough for resale purposes. I also wanted to prove the mDrive because I was having painful popping issues in my left knee which made clutching very uncomfortable. It’s got 3:40 S38R rears rated for 150,000lbs and the Twin Y suspension rated for 160,000lbs. 

To address the power concerns of the 13 Litre engines, my experience in the last 10 years has been that the 15 litre no longer has an advantage and in longevity. The C15 has been the last big block that was built for the heavy haul industry. The ISX and the DD15 can in no wise compete with the durability and power capabilities of the C15 although in stock form they were somewhat hard on fuel. 

As far as 13’s go I can only speak for the MP8 because it’s the only one that I have driven extensively but I run with the others quite frequently. In regards to 15’s, I have put many miles on both the C15 and the ISX and I ran for a year with someone that had a DD15.

The only advantage to the 15 in the newer emissions compliant engines is the low end off the line in low range. Once the the engines require the turbo to spool up the MP8 dominates. Interesting fact on that note is that the ISX and the MP8 use the exact same Holset turbo with the MP8 consistently putting out up to 5 psi more boost. ISX will generally run 38 psi with the MP8 running from 42-47 psi. It’s also surprising how low the MP8 can lug down and still recover with dignity. This again was a C15 strong point. The ISX on the other hand is practically dead at 1200 rpm. I’ve had my MP8 touch 900 and still pick it up in top gear pushing 35 psi boost. The DD15 also has no low end holding power. Example: 5 Years ago I was westbound with an O/O with a 2011 WS DD15 565hp 1850tq. Those were his claims if the numbers don’t seem right to you. Just west of Indian Head SK there’s a 4 mile stretch of what I’m guessing  is 2% grade some spots maybe 3%. He had an 18 with 3:70 rears and I was running an MP8 505 / 1760 with an 18 and 3:55 rears. I overtook him and at neck to neck point he told me on the CB that he had already split back and I was still in top gear at 1100 rpm. Throughout the time he had that truck I would consistently outperform that DD15 no matter what the incline. He also couldn’t match my fuel economy. 

On the engine braking side of the MP8, I’ve heard of some bad ones but I’ve never had one. With the 18 spd I generally shifted 1400-1200 and engine brake I ran 1600-1400. The mDrive with the loads I pull shifts 1500-1200 and it downshift 1400-1100 with the engine brake. When I manually downshift I go 1600-1300. I use the Maxibrake about twice a week maybe just for kicks and it will run as high as 1800 or 2100 depending on load. The Powerleash on the MP8 has stunned many drivers and O/O alike with how much retardation power it puts out. I get comments all the time when running with someone else. There’s been many a Hopped up 15 litre that can’t wait for me to speed up but when it comes to slowing down they’re speechless. 

The only thing I’m yet looking for on my MP8 is a safe way to gain 50-100 more bulldogs under the hood for a 0.5 mpg saving on my bottom line. I’ve heard that the magic formula for fuel economy is 240lbs per hp so that’s roughly 600 hp in my line of work. In Canadian winters I average from 4.6-5.2 mpg and in summer it’s 5.7-6.2 mpg. 

Are there any more concerns on the capabilities of the 13 litre trend? I’m sure there’s veterans out there with a lot more than my measly 10 years experience in the heavy haul field that could fill in the blanks and even correct my logic. 

[Maxidyne]

Thanks for providing a vast addition to our knowledge base on this topic! The MPG you're getting is impressive, are those U.S. or Imperial gallons?

[GoldDog44]

I’m in Canada. Lol. It all Imperial. 

[Maxidyne]

Still very impressive ton/MPG numbers, given that you're hauling darn near twice as much as our 80,000 pound rigs in most of the U.S..

[GoldDog44]

I have a friend who did long haul deck work for many years. He then became a salesman for Mack a couple years and now he stays home on the farm. He once told me that diesels are creatures of habit, where you first break them in is where they will always perform best. I have found that to be true. When we would switch trucks from A-Train to Super B the power and fuel difference was Phenomenal. This is with twin trucks with the exact same specs except having started life pulling different weight. Which makes me wonder if my truck wouldn’t do a bit better if it hadn’t previously been a reefer truck.  Food for thought. 

[HeavyGunner]

I agree with you on the dd15 not having the grunt to hold and keep pulling. I’m sure others in here are tired of my dislike of the dd15 but it’s a dog. The last cat we had here (truck specd the same as the others except for engine) would walk all over these Detroit’s and usually use less fuel. I’m usually somewhere between 3.8-4.4 depending on winter fuel or not. 

[david wild]

with 80 tires on the ground, 414,000 gross no matter what engine, we used all, DT hubs 18 speed 2 speed aux, estatic with 1 MPG.

[Hayseed]

On 2/9/2018 at 12:38 AM, GoldDog44 said:

It’s got 3:40 S38R rears rated for 150,000lbs and the Twin Y suspension rated for 160,000lbs. 

GoldDog, Whats your opinion of the Twin Y Suspension??

I've been pricing up a new truck lately, & Mack have been refusing to Quote Me a twin Y.. Plus It's only available here with a 50,000kg (110,000lbs) Rating...

[GoldDog44]

Before I bought the truck I was advised to stay away from the Twin Y because it is a Volvo part Number called the Twin Blade suspension. With buying a used truck you can’t control those options though.
The suspension itself is a very simple but effective design and I can easily see why they would have decided to reduce the rating on it, if that is what they did. I find it rides very well and it’s holding up fairly well with my many miles of gravel and farmyard use. I have 37,000-39,000 lbs on my drives most of the time and I think it’s a little softer than it should be. When you look at how it’s built, I have my concerns on how it’s rated at 160,000 lbs but I’m not an engineer. There’s really not a lot of beef too it. It has bottomed out a number of times crossing some rural railroad crossings but I have no complaints. My wheelbase is quite short but the ride quality is excellent and I give credit to the softness of the Twin Y. I think in the 110,000 lb weight class it would shine.
When I was looking around one salesman told me to look at the Holland Neway suspensions. They have some awesome independent long travel options if that’s what you’re looking for.


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[james j neiweem]

Do they make the Twin -Y in different weight ratings. As simple as the system seems to be it would only require thicker metal stampings.

[HeavyGunner]

In another thread mackpro or Macktechnician commented on the twin y suspension saying there was a recall and upgrade. I think he said under heavy emergency braking the y arms were twisting or bending because they’re too light. 

[GoldDog44]

4 hours ago, james j neiweem said:

Do they make the Twin -Y in different weight ratings. As simple as the system seems to be it would only require thicker metal stampings.

That would seem very logical but I'm not sure that's the case. 

[GoldDog44]

8 hours ago, Hayseed said:

GoldDog, Whats your opinion of the Twin Y Suspension??

I've been pricing up a new truck lately, & Mack have been refusing to Quote Me a twin Y.. Plus It's only available here with a 50,000kg (110,000lbs) Rating...

I looked it up for you. The 40,000kg rating is for 4x2 applications. It's the 6x4 that gets the 160,000 lb rating. https://www.macktrucks.com/powertrain-and-suspensions/suspensions/twin-y/

[Hayseed]

2 hours ago, GoldDog44 said:

I looked it up for you. The 40,000kg rating is for 4x2 applications. It's the 6x4 that gets the 160,000 lb rating. https://www.macktrucks.com/powertrain-and-suspensions/suspensions/twin-y/

Not here in Australia..

 

The twin Y is only available on the Granite, & only with the S40 Axles & In a single trailer (50,000kg) Rating..

 

http://img06.en25.com/Web/VolvoAUS/{23b2ee29-64e1-48d0-8b50-d52a1ffefcc2}_granite_distribution.pdf

 

https://www.macktrucks.com.au/-/media/files-au/brochures/axlessuspensionbrochure122015.pdf?as=1&la=en

[Hayseed]

8 hours ago, GoldDog44 said:

When I was looking around one salesman told me to look at the Holland Neway suspensions. They have some awesome independent long travel options if that’s what you’re looking for.

I agree..They're only only available here in Australia with Kenworth though. The other 2 Truck manufacturers (Mack & Iveco) Fit Hendrickson Primaxx suspension for those Applications..

[GoldDog44]

35 minutes ago, Hayseed said:

Not here in Australia..

 

The twin Y is only available on the Granite, & only with the S40 Axles & In a single trailer (50,000kg) Rating..

 

http://img06.en25.com/Web/VolvoAUS/{23b2ee29-64e1-48d0-8b50-d52a1ffefcc2}_granite_distribution.pdf

 

https://www.macktrucks.com.au/-/media/files-au/brochures/axlessuspensionbrochure122015.pdf?as=1&la=en

I guess I can’t help you then. The design spec said that it’s engineered for 2050 tq as well which would make available even on a Titan or Superliner. 

[Hayseed]

34 minutes ago, GoldDog44 said:

I guess I can’t help you then. The design spec said that it’s engineered for 2050 tq as well which would make available even on a Titan or Superliner. 

Actually, you have Helped Me. With giving your real world hands on, opinion of your twin Y in What appears to be similar type of Operating Conditions..

Edited February 11, 2018 by Hayseed

[GoldDog44]

Actually, you have Helped Me. With giving your real world hands on, opinion of your twin Y in What appears to be similar type of Operating Conditions..

Glad to be of service.


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