AMI 370 power increase

[03' Big Red]

I have a 2003 RD688s with a AMI 370, the VIN is 067246

I would like to bump up the horsepower by about 100

What do I need to do for this increase?

I’ve read other post on this site about offset camshaft key ways and swapping in a older E7 exhaust manifold,turbo and 5” exhaust to allow the engine to breathe better.

I prefer staying with factory style injectors if possible since I’ve had aftermarket injectors in the past and found them to be unreliable.

So with the above information what would turbo and injectors would be needed for a 100 HP increase?

 

 

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[Mack Technician]

If you add 100 your a 370, drop it to 460 and you need;

631GC5172M3 turbo (which I have for sale for 10% of new price, if you are staying stock)

736GB419M3 injectors (if your staying stock)

Your on your own for ECM software. Site is still mourning Mpro's departure.

Your truck will be set up as AMI not AI, but the peaks may overlap well enough since AI-460 has a long, flat, top.

Pay attention to torque rating of clutch, trans, driveline, etc.

Edited October 27, 2019 by Mack Technician

[03' Big Red]

The ECM has been updated to the AMI 370
it was a AMI 350 that ran horrible.



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[Mack Technician]

Pretty good overlap. I wouldn't guess, but the torque curve touch may indicate the rating for your clutch would have been o.k. ..IF...it wasn't for the fact your running AI-350 hardware. AI-350 is soft on torque, do some homework on your driveline to be sure your fit.

 

I marked your Ftlbs./HP differential in the curves.....

Mack 370.pdf

 

 

Edited October 5, 2018 by Mack Technician

[03' Big Red]

Yeah
I know I am at my limits now with the trans.
It’s rated at 1490 and the AMI 370 is 1480 ft lb of torque
But hey it sure is much nicer to drive than the AI
Much like a old school Maxidyne


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[Mackpro]

What tire size on the rear and what rear end ratio you running ?  Hopefully 4.42 or 4.74  in rears if running full size 24.5

[03' Big Red]

4.42 and 24.5


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[Maxidyne]

Does your transmission have close enough splits to work with the 460's 1450-1950 RPM powerband?

[03' Big Red]

I run the Eaton 8LL
I would never go with the 460 since
My power band is 1200-2150


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[Maxidyne]

Sounds like your transmission has close enough ratio gears, but maybe not enough torque capacity to go to 460 HP. This HP upgrade might not be worth the cost and time- Unless you're running over 80k pounds GCW or up and down mountains all day the 460 will mostly add power only on the top end and won't cut trip times much.

[03' Big Red]

I’ll be swapping out the trans as part of my maintenance program... fix it before it breaks... the 8 LL
Has over 500,000 miles
I’ll step up to a 9 LL with higher tq rating


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[Mack Technician]

Every AI falls on it's face in the low hole. With AI the number differential just gets worse as the HP band increases.

 

E-Tech 350 has 1250 Ftlbs of torque at 1,100 RPM

AI-350 has 1050 Ftlbs of torque at 1,100 RPM

 

E-tech 400 has 1350 ftlbs @ 1,100 RPM

AI-400 has 930 Ftlbs @ 1,100 RPM

 

E-tech Maxidyne 275HP has 1310 ftlbs @ 1,000

AI Maxidyne 300 HP has 775 ftlbs @ 1,000 RPM

 

E-tech 460 has 1,450 Ftlbs @ 1,100 RPM

AI-460 has 1,000 Ftlbs @ 1,100 RPM  

 

Don't think in terms of "I may be wrecking my low torque" since you already never had it...….Think in terms of "I have none with an AI engine, how am I going to get it". Top ends are not a disappointment, the bottom ends all are.

My best guess is the emissions test required the low RPM to emit less and they could not get the scavenging to lower the combustion temps to stop NOX. In turn they reduced fuel delivery so the lugging, long dwell time, of combustion could not get so hot. The fuel mapping is the issue so you manipulate it back.   

Edited October 5, 2018 by Mack Technician

[Maxidyne]

That's always been my suspicion, seems like they moved the power to higher RPMs in the ALs to meet emissions.

[03' Big Red]

The AMI 370 is rated at 1480 Ft lb tq at 1300 rpm but it will pull down to 1200
405 hp from 1700-1900
370 hp at 2150

Not at all like the AI series !
sadly I hear this file is no longer available from Mack


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[Mack Technician]

370 is a good one, but you will never have a Maxidyne oxbow in your torque curve without modification. 

[03' Big Red]

If you add 100 your a 470, drop it to 460 and you need;
631GC5172M3 turbo (which I have for sale for 10% of new price, if you are staying stock)
736GB419M3 injectors (if your staying stock)
Your on your own for ECM software. Site is still mourning Mpro's departure.
Your truck will be set up as AMI not AI, but the peaks may overlap well enough since AI-460 has a long, flat, top.
Pay attention to torque rating of clutch, trans, driveline, etc.

Would this be the Turbo needed for a E7 exhaust manifold?
I want to go that route since the ports are much bigger and allowed better breathing.
I think it’s a Q400 series versus the Q300 used on the AI,AMI


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[03' Big Red]

Sounds like your transmission has close enough ratio gears, but maybe not enough torque capacity to go to 460 HP. This HP upgrade might not be worth the cost and time- Unless you're running over 80k pounds GCW or up and down mountains all day the 460 will mostly add power only on the top end and won't cut trip times much.

I not concerned with cost since I plan to replace the trans and all my work is by the hour, it’s purely for driver enjoyment !


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[03' Big Red]

Every AI falls on it's face in the low hole. With AI the number differential just gets worse as the HP band increases.
 
E-Tech 350 has 1250 Ftlbs of torque at 1,100 RPM
AI-350 has 1050 Ftlbs of torque at 1,100 RPM
 
E-tech 400 has 1350 ftlbs @ 1,100 RPM
AI-400 has 930 Ftlbs @ 1,100 RPM
 
E-tech Maxidyne 275HP has 1310 ftlbs @ 1,000
AI Maxidyne 300 HP has 775 ftlbs @ 1,000 RPM
 
E-tech 460 has 1,450 Ftlbs @ 1,100 RPM
AI-460 has 1,000 Ftlbs @ 1,100 RPM  
 
Don't think in terms of "I may be wrecking my low torque" since you already never had it...….Think in terms of "I have none with an AI engine, how am I going to get it". Top ends are not a disappointment, the bottom ends all are.
My best guess is the emissions test required the low RPM to emit less and they could not get the scavenging to lower the combustion temps to stop NOX. In turn they reduced fuel delivery so the lugging, long dwell time, of combustion could not get so hot. The fuel mapping is the issue so you manipulate it back.   

Wow that’s a surprise, so if one is going for torque versus Horsepower then sticking with a AI 350 would give you more than the AI 460


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[Mack Technician]

7 hours ago, 03' Big Red said:

Wow that’s a surprise, so if one is going for torque versus Horsepower then sticking with a AI 350 would give you more than the AI 460


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Yup, it’s messed up to pull with a stock AI460, you either are balls to the walls or panicking at an intersection because the torque dropped out and your stalling ocause you grabbed a low hole. They are IMO the worst version (if left Un modified) since they are torque bipolar and naturally your hauling big because it is suppose to deliver. 

Do turbo, manifold and injectors at the same time or you won’t be satisfied. If you’ve had bad luck with your locally available aftermarket try K&S. I’m not making a dime recommending them and you’ll be paying half as much as Rochester. I talked to Mike last week when buying some injectors and he said I sent 10 BMT operators to him (scattered over the lower 48) with 10 for 10 being 100% satisfied. Modify the 370. I believe Mack Pro gave a complete list of injectors and turbo numbers for AI engines two threads ago, including your 370. 

Edited October 6, 2018 by Mack Technician

[Mack Technician]

2 minutes ago, Mack Technician said:

Yup, it’s messed up to pull with a stock AI460, you either are balls to the walls or panicking at an intersection because the torque dropped out and your stalling cause you grabbed a low hole. They are IMO the worst version (if left Un modified) since they are torque bipolar and naturally your hauling big because it is suppose to deliver. 

Do turbo, manifold and injectors at the same time or you won’t be satisfied. If you’ve had bad luck with your locally available aftermarket try K&S. I’m not making a dime recommending them and you’ll be paying half as much as Rochester. I talked to Mike last week when buying some injectors and he said I sent 10 BMT operators to him (scattered over the lower 48) with 10 for 10 being 100% satisfied. Modify the 370. I believe Mack Pro gave you a complete list of injectors and turbo numbers for AI engines two threads ago, including your 370, so you can pick and choose whatever you decide to do. 

 

[03' Big Red]

Yup, it’s messed up to pull with a stock AI460, you either are balls to the walls or panicking at an intersection because the torque dropped out and your stalling cause you grabbed a low hole. They are IMO the worst version (if left Un modified) since they are torque bipolar and naturally your hauling big because it is suppose to deliver. 
Do turbo, manifold and injectors at the same time or you won’t be satisfied. If you’ve had bad luck with your locally available aftermarket try K&S. I’m not making a dime recommending them and you’ll be paying half as much as Rochester. I talked to Mike last week when buying some injectors and he said I sent 10 BMT operators to him (scattered over the lower 48) with 10 for 10 being 100% satisfied. Modify the 370. I believe Mack Pro gave you a complete list of injectors and turbo numbers for AI engines two threads ago, including your 370. 

He did although I wasn’t sure if the turbo was for a earlier style no AI manifold


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[Mack Technician]

I’ll check Monday if you want? My tune up manuals are in my box at work. 

When I get time, and if I have space allowance, I may scan and upload my AI charts to the main Thread. 

[03' Big Red]

That would be awesome!


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[OldRedMack]

I have a ami370, put on an etech exhaust manifold, went to the 427/460 injectors from k&s thanks to mack tech and they were great to deal with, and had the local turbo shop build an s467 with a billet wheel.  The truck makes 44psi of boost and runs like a monster, fun to drive now.

[03' Big Red]

I have a ami370, put on an etech exhaust manifold, went to the 427/460 injectors from k&s thanks to mack tech and they were great to deal with, and had the local turbo shop build an s467 with a billet wheel.  The truck makes 44psi of boost and runs like a monster, fun to drive now.

Any idea what kind of horsepower you have now ?


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