Anyone have their Cummins L9 tuned up from 400-450 HP?

[jcussen]

Originally Posted by Cat320

I'm not sure you mean by this comment. Allison transmissions used in MHs have the following max limits:

Allison 3000, 450 HP and 1,250 torque.
Allison 4000, 650 HP and 1,950 torque.

Torque remains the same, but hp is calculated using torque at a certain engine speed so an engine that produces max torque at a higher engine speed will have more hp than the engine with the max torque at a lower engine speed.
So if ecm is modified so max torque band goes from say, 1200 to 1600 rpm to 1200 to 2000 rpm, horsepower will increase.

https://www.wikihow.com/Calculate-Ho...f-Your-Car_sub

[Vickie 4369]

Originally Posted by beenthere

ya know they still did it to older models. there req's are not changed from 5 or 10 yrs ago to now, you say it has to meet specs well the engine will meet specs. just like yrs ago. are you saying they will not now upgrade like they did previously?? hmm/

Not what I am saying at all.

Different year models may need other components to move up to the next power level like injectors, turbos, fuel pumps etc.

My dealer had to call Cummins to find out exactly what was needed for my Vehicle ID number.

In my case it is just a Reprogramming of the Engine control module.

[Vickie 4369]

Originally Posted by Cat320

I'm not sure you mean by this comment. Allison transmissions used in MHs have the following max limits:

Allison 3000, 450 HP and 1,250 torque.
Allison 4000, 650 HP and 1,950 torque.

We are not exceeding any torque limits again this is a fully warranted upgrade available at your cummins dealer.

If you were to lay the two torque graphs on top of each other for the L9 400 and L9 450 there is no difference in torque at 1400 rpm both are 1250 lb ft.

As you move toward 2100 rpm on the graph the 2 lines separate with around 130 lb ft more at 2100 giving us the extra 50 hp.

Torque X RPM / 5252 = Horsepower.

Ted.

[Smitty77]

My understanding is that after the parts checks on engine build components (Cummins) and primarily cooling related (Chassis, Freightliner in this case.) are a 'Go', you should not have much concern about reliability.

Coach Manufactures order detuned HP engines, ISL in this case, to separate the model lineup... For decades, and decades - HP was part of the selling process. Higher up the good chain coaches, and price point, received the higher HP engines. (On Edit: A good example is our Country Coach 04 Allure with ISL370. I went in with a flashlight and mirror to confirm the engines serial number, and the identification plate had it as an ISL400. Cummins confirmed that the ECM coding was a detuned (My choice of wording.) ISL370 version. And brought up the side by side HP/Torque curve of going to the ISL400 ECM coding. While not as dramatic as the Common Rail with Variable Geometry Turbo ISL400 - our CAPS era 400 flash did have a broader HP/Torque curve then the 370 version.)

If a coach is out of Cummins warranty period, then the cost to have the ECM reprogramed to in this case, 450HP trim, is not too expensive. Somewhere between $350-500 - depending on how the specific facility cares to gauge you for what is a zero parts cost, and usually less then 30 min of hooking up the computer job...

I also agree, that some engines will not have the appropriate build components to handle the extra HP/Torque. And in this case Max Torque will be the same, not always, on older ISL and ISC's engine is this the case. But both HP and Torque curves will be sweeter for running. And that is probably the biggest payback, the few times you are driving up a mountain thos 50HP do help. But all the time your driving, the broader range of HP/Torque curve helps with drivability...

Good luck, and best to all,
Smitty

[algolfer]

I have not had the upgrade performed but am very interested in the outcome. Please keep us posted.

[Vickie 4369]

Originally Posted by algolfer

I have not had the upgrade performed but am very interested in the outcome. Please keep us posted.

Will do.

[wjohnson913]

Had my L9 upgraded to 450 from 380 and torque went from 1150 to 1250. My Powerglide cooling capacity was designed for up to 450HP.
The power difference was more than just a little noticeable, it was better than I hoped. Pulls the grades faster with less throttle input and a slight improvement in fuel mileage.
I’d do it again in a heartbeat. I paid 2600 bucks.

[Vickie 4369]

Originally Posted by wjohnson913

Had my L9 upgraded to 450 from 380 and torque went from 1150 to 1250. My Powerglide cooling capacity was designed for up to 450HP.
The power difference was more than just a little noticeable, it was better than I hoped. Pulls the grades faster with less throttle input and a slight improvement in fuel mileage.
I’d do it again in a heartbeat. I paid 2600 bucks.

This is what I was looking for thank you for posting your experience.

How many miles were on your coach when you had it done

How many miles have you put on so far with the new power?

[Vickie 4369]

Peak Torque is what stresses components not Peak HP.

If we could carry the 1250 lb ft from 1400 rpm flat to 2100 RPM we would have 500 hp and no added stress on components.

But engines do not typically work that way they reach peak torque very quickly then slowly fall off with RPM

Here is the HP and Torque Graph for this calibration

[wjohnson913]

Originally Posted by Vickie 4369

This is what I was looking for thank you for posting your experience.

How many miles were on your coach when you had it done

How many miles have you put on so far with the new power?

We had it done at our first service service at about 9000 miles and have had it for a year about another 9000 miles.
We tend to stay on the west side of the country so we always seem to be pulling grades weather it’s Utah or Montana or Colorado. We pull a Jeep and the coach is loaded for full time use.
One of my favorite mods to my coach. We own a Tiffin and you can order it with the 450/1250 set up for about 12K list MSRP but Cummins service centers will do it for a fraction of the cost.

[vito.a]

I would want to compare the graph above to your current 400hp L9 graph to see what you are getting for your money.
It looks like the new program will achieve peak torque at 1400rpm and peak hp at 2050rpm.
You do realize this modification will be much less expensive once your warranty expires?

I wish we could bring back the Cummins ISM with 1550 Ft lbs! It was a great engine with good power to weight.

[jcussen]

Originally Posted by vito.a

I would want to compare the graph above to your current 400hp L9 graph to see what you are getting for your money.
It looks like the new program will achieve peak torque at 1400rpm and peak hp at 2050rpm.
You do realize this modification will be much less expensive once your warranty expires?

I wish we could bring back the Cummins ISM with 1550 Ft lbs! It was a great engine with good power to weight.

For sure, and you did not have to wind it out to max out hp. 1800 rpm was 500 hp. Believe it"s a lot easier on the engine than 2000 rpm+
https://www.rvtechlibrary.com/engine/ISM500_specs.pdf

[Vickie 4369]

Originally Posted by vito.a

I would want to compare the graph above to your current 400hp L9 graph to see what you are getting for your money.
It looks like the new program will achieve peak torque at 1400rpm and peak hp at 2050rpm.
You do realize this modification will be much less expensive once your warranty expires?

I wish we could bring back the Cummins ISM with 1550 Ft lbs! It was a great engine with good power to weight.

I have it at home I will try and post it later.

[Field Trip]

Does anyone have any idea what the change from 400 to 450 will do to your fuel economy? DEF usage?