Isl8.9 350hp?

[dlfishing]

Is there a reason Dynamax orders this engine with the lower HP?
I spoke to a Freightliner dealer this week and was told that it’s no problem to go to 380 HP with a program reconfigure. He couldn’t tell me, without putting my DX3 in the shop, how high the hp could go without having to make significant physical changes such as injectors and radiator to get 450 HP from this engine.

He said for short haul use they recommend the 350 hp configuration but for long haul, as we use them, there is no reason not to boost it. He also says that my fuel consumption shouldn’t change.

Before I get this upgrade I would like to know if there is a downside

[RockHaulerLarry523]

The "fuel consumption shouldn't change", could turn into "your fuel mileage has dropped, due to how you drive it." I, personally, don't have any problem with the power of the coach. I just think it shifts too fast and bogs the motor down too much.
If it is something you want, go for it. Just be sure to have a certified Cummins shop do it. There are too many parking lot programmers out there, screwing up engines

Larry

less than 50 days to get it out of storage

[dlfishing]

Thanks, I tend to agree. I’ve sent an inquiry to Cummins as to the advantage of 350 hp vs 380 hp. As this engine can be tuned.
If I drove primarily in mountain country then I might be willing to sacrifice some fuel economy.
When I get a response from Cummins I will post it.

[mookieblaylock]

I know others on here have looked into this as well.

On Friday, I decided to ask my local Cummins service center about it too. I gave them my engine serial number and hope to hear something definitive tomorrow.

It’ll be interesting to compare notes.

[RV Randy]

The M2 106 chassis, as used on our MH's, IMHO will handle the additional HP just fine. If you go to the 450 HP XL they put it in the heavier chassis with a slightly larger radiator. Remember, these are commercial truck chassis so they build them to safely handle maximum load. If you had a 450 HP engine with loads of torque and you were using it to haul 50K of gravel, you can see the frames torque over when they first start off. If you're hauling that load up a long, steep hill, you will create some heat thus the larger radiator.

Only going up 30 - 40 HP should be no problem. The trans is rated to handle more HP and weight than the upgrade would result in. Unless you are grossly over loaded pulling steep long grades in the mountains, you should not see over heating. Could the temp gauge go up 10 - 15 degrees, sure, but diesels like to run warm as long as you don't move into the over heat range.

On my 2013 Cummins 6.7, I had the Cummins dealer upgrade it the same amount. It is pricey but the engine is still covered by full factory warranty. I will get the same info on the 8.9 now that I have my VIN number. They will also check the CPI list (critical parts index) to see how high you can go before you have to go to a bigger turbo, injectors, pump, etc.

The bigger question is, is it worth the cost to get that modest increase in HP and torque? And yes, you will burn more fuel, especially pulling long hills, but it won't be a night & day difference. Running on the flatlands, head winds and your consistent speed have a much larger impact on MPG than the HP rating

[dlfishing]

RV Randy
Was the upgrade worth it to you and will you have it done on your new DX3.
Dealer told me a couple of hours so $200 to $300 my cost.

[The Renegade]

Originally Posted by dlfishing

RV Randy
Was the upgrade worth it to you and will you have it done on your new DX3.
Dealer told me a couple of hours so $200 to $300 my cost.

Wow that sounds really reasonable.

[bclemens]

We haven't done it due to cost mainly. You can bump the L9 to 1150 ft lbs of torque...but for what I would charge to get that, it did not seem a reasonable trade off (to make 100% of the people buy it) when you can get it done after the fact for about the same amount (for the small percentage that want it). HP we have not looked that hard into, but I know when we looked at bumping HP and torque it was going to be about $3800-$4200 MSRP.

[mookieblaylock]

The conventional Internet wisdom on the subject indicates the 'after the fact' cost would be around $2500...most all of that being to update the warranty to reflect the motor change and very little of that being to perform the actual work (an hour or so of labor as mentioned above). If you were out of the warranty period, then the upgrade would be significantly less expensive.

If I had to guess, they're going to say that the 380 HP spec is as high as you can go and still be covered by their warranty. That's the highest 'performance' spec they (Cummins) publish for their Medium Duty version of the 8.9. That being said, though, that configuration increases the peak torque to 1250 ft-lbs. So, while the HP gain is minimal, the torque is equivalent to that offered in their highest 8.9 configuration (450 HP/1250 ft-lbs). At and around peak torque (1400 - 1500 RPM), both configurations will be making exactly the same HP - 340-350ish. The only difference being that with the 380 HP version, the torque curve will fall off more quickly/steeply than the 450 HP version.

If this is the way it shakes out, for $2500, I'd give this a shot.

[RV Randy]

Originally Posted by dlfishing

RV Randy
Was the upgrade worth it to you and will you have it done on your new DX3.
Dealer told me a couple of hours so $200 to $300 my cost.

It was about $1500 versus the $200 - $300 estimate you got. The 6.7 was really struggling with the heavy trailer I pulled. The upgrade improved it but here I am still buying a DX3 to get better pulling & stopping performance.

But I will drive the DX3 as-is for now to get an idea of how it performs stock pulling the trailer across the mountain passes. If it does OK, then I will probably leave it alone just to save the money. I don't care if I'm not passing people going up the long grades, I just don't want the rig struggling to maintain minimum speed.

[The Renegade]

Originally Posted by RV Randy

I don't care if I'm not passing people going up the long grades, I just don't want the rig struggling to maintain minimum speed.

You race cars man.... Its in your blood to wanna pass. You cant help it..

[RV Randy]

Originally Posted by Mountieman

You race cars man.... Its in your blood to wanna pass. You cant help it..

True, but just in case my DW reads this thread I have to stick to my original story. Then if it is actually a little light on power, I will wait until she says "can't you do something to give it more power?". That's one reason why I married her, she has said more than once "you need to build another car that is faster".

[dlfishing]

RV Randy.
Did you have physical changes made or was there a charge for the warranty change?
Just reprogramming can’t possibly cost that much.
Same comment for Brian cost.
What happened to your mileage after your upgrade, pulling the same load?

Mine is out of warranty so that’s not an issue.

[The Renegade]

Originally Posted by RV Randy

True, but just in case my DW reads this thread I have to stick to my original story. Then if it is actually a little light on power, I will wait until she says "can't you do something to give it more power?". That's one reason why I married her, she has said more than once "you need to build another car that is faster".

LOL... Thats great. And you have not started the new car yet??? Kinda like Tim Allen the comedian... Need more horsepower just strap a Jet engine in and roll on...

[RV Randy]

Originally Posted by Mountieman

LOL... Thats great. And you have not started the new car yet??? Kinda like Tim Allen the comedian... Need more horsepower just strap a Jet engine in and roll on...

Of course I have built at least 3 new cars on the fact she thought I should have a different one. Of course she used that ploy in her favor too and got a 911 Carrera out of the deal. But I get to drive it too so I "gave in" on that one.

[mookieblaylock]

I just talked to a tech at the local Cummins service center, and he said, based on the CPL, 350 HP is the max for this engine. I asked about an increase in torque but did not get a clear answer. Based on the Freightliner documentation and comments from Brian in this thread, they should at least be able to increase the peak torque to 1150 ft-lbs, but he wouldn't commit to that.

I had to call just about every day to finally get them to look into it. They're likely super busy, but I kind of got the impression this isn't something their terribly interested in doing. I get that. I'm interested to hear what you guys discover.

[RV Randy]

Originally Posted by mookieblaylock

I just talked to a tech at the local Cummins service center, and he said, based on the CPL, 350 HP is the max for this engine. I asked about an increase in torque but did not get a clear answer. Based on the Freightliner documentation and comments from Brian in this thread, they should at least be able to increase the peak torque to 1150 ft-lbs, but he wouldn't commit to that.

I had to call just about every day to finally get them to look into it. They're likely super busy, but I kind of got the impression this isn't something their terribly interested in doing. I get that. I'm interested to hear what you guys discover.

That is a typical response if you just call. But if you agree to take the coach in and pay the $170 fee for the tech to plug the rig in and read all of the info, they will give you an accurate answer. As to the cost of the SW re-flash they do not base the amount you pay on the 1 hour it takes to perform the flash. They do "value added" pricing not cost plus margin. If you bought a truck new with a 380 HP rated 8.9 and that option was $3,000 more than a 350 HP version (I'm just guessing at the number)
why would they sell you that option after the fact for a couple of hundred dollars? They also have to recover their R&D investment in developing the multiple SW versions. Nowadays the margins manufacturers make on the sale of new hardware is minimal due to competition, so a big chunk of the profits they make comes from SW, after sales add-ons and service.

[mookieblaylock]

I wasn't looking to get this done for couple hundred bucks. Above, I posted where I expected the upgrade to be in the $2500 range, and I made it clear to the Cummins folks that I knew that going into this. I fully understand why they would charge that much.

If I have to take it in and pay their $170 fee for them to give me an accurate answer, then so be it. It just seems like a) they would tell me that and b) based on the actual engine serial number, this wouldn't be necessary.

[dlfishing]

I will bring mine in to the same Freightliner dealer that gave me the estimate and get a hard dollar quote. It may be that they are not aware of what Cummins might charge for the code.
I don’t need it bad enough to spend $3K.