the differaces between mack ac and ai engines ?

[41180]

im just wondering what the differance is between mack ac and ai engine series is. i know they had differant hp and torque ratings . im wondering which one is better ?

[daveigou]

The AI / AC designations have to do with EGR. 2004 model year was the first year for the ASET (application specific engine technology)(A) engines, AI for internally cooled, and AC for externally. The AI engine used an additional bump on the camshaft to pull back a portion of exhaust to mix in with the next intake stroke. The AC engine used an external cooler.

The two engines were not interchangable, if you bought a vocational truck, you got an AI, if you bought a highway model, you got an AC. Both had their problems, the AI's were poor low end performers, and accumulated alot more contaminates in the crankcase, but were fairly reliable with "old style simple" turbos. The AC's generally performed fairly well, but were plagued with exhaust manifold leakage, and (VGT) turbo, and cooler problems.

With both engines, maintanence is very critical to follow recommendations.

[Mackpro]

We lost alot of customers in 2004 when they bought CX's and CH's with the AC engines. Had to change the fan belts at every oil change (due to under hood heat damage), EGR cooler failures, turbos every 80-100K miles, fan hub failures. It was bad. Afew of the customers traded them in for CV's with the AI engine set up as daycab road tractors, alot less issuses but poor MPG. The CHN's and CXN's with AC engines came out ayear later much improved and things got better as turbos, fan hubs, belts and tensioners were improved/updated. But that bad 2004 year cost us dearly here!

[Olivetroad]

. Had to change the fan belts at every oil change (due to under hood heat damage!

OUCH!

[Green Dash]

We lost alot of customers in 2004 when they bought CX's and CH's with the AC engines. Had to change the fan belts at every oil change (due to under hood heat damage), EGR cooler failures, turbos every 80-100K miles, fan hub failures. It was bad. Afew of the customers traded them in for CV's with the AI engine set up as daycab road tractors, alot less issuses but poor MPG. The CHN's and CXN's with AC engines came out ayear later much improved and things got better as turbos, fan hubs, belts and tensioners were improved/updated. But that bad 2004 year cost us dearly here!

We have had problems with Visions from that era where the turbo takes forever to build up boost. It's a bit frustrating when your trying to get rolling after stopping on a hill.

[41180]

thanks so it sounds like the ai is better

[motortrans]

sounds like a pre 2004 is the best!!

[41180]

YES NO DOUBT WE HAVE A E9 500 TWO VMAC 2 427 AND 454 AND 2 ETECH 460XT ALL ARE RELIABLE WITH NO B.S.

[daveigou]

thanks so it sounds like the ai is better

That's not exactly what I said. I Sold a Granite tri-axle dump truck with an AI 427 engine to a customer in Delaware. After about two weeks he called me up and told me not to take this personally, but his driver refuses to run it, and I just sold him the biggerst piece of s__t he ever bought.

When I said AI low end performance was bad, it was really bad. Even though they were fairly reliable, alot of customers hated them.

The AC's had reliability issues from the start, but by 2006 and 2007 they were doing much better.

sounds like a pre 2004 is the best!!

Yes, but the Etech (1998 -2003) got off to a bad start too. The problem there was camshaft failures, mostly caused by follower issues that started to skid on the camshaft and wiped it out.

As a Mack salesman at the time, I could not wait for the MP (Volvo) engines to come to market. In the end of 2007 model year, Mack did a short run Of CTP's (Granites) and CXP's (Visons) with MP7engines, but without the DPF exhaust after-treatment systems. The top horsepower ratings were 395 and 405, the 395 being actually a higher torque rise than the 405 hp, and most customers turned their nose up at them because they were "not enough" horsepower. One fleet I sold six of the 395's to said they did better than their previous 427's. For being totally new, they did very well. If you happen across one of those in the used truck market, I would think they would be pretty desirable.

[03' Big Red]

all of this talk sounds like my 2003 RD688s with a AI 350, there are many times i wish i didn't buy that truck, i sure hope there is something that can be done.

[daveigou]

I don't think the AI engine went into any RD's. If your truck is a 2003, it should be an Etech. Have you had your truck back to a good Mack service department to get checked out? That's always the best place to start.

[Rob]

I don't think the AI engine went into any RD's. If your truck is a 2003, it should be an Etech. Have you had your truck back to a good Mack service department to get checked out? That's always the best place to start.

Hey Dave, thanks for explaining the AI, and AC engine differences. I've not been around much that is electronic in diesel engines and know very little. etec, vmack, and the like are "foreign" to me.

Rob

[03' Big Red]

I don't think the AI engine went into any RD's. If your truck is a 2003, it should be an Etech. Have you had your truck back to a good Mack service department to get checked out? That's always the best place to start.

Harrisburg Mack claims it's the AI 350. the truck is at Garden Spot Frame and alignment today, they checked fuel pressure and its about 30 psi low on a cold motor so a new lift pump is on the way, i hear this is a typical problem for a Mack. they will also be adjusting the valves since that most likely was never done by the previous owner.

what is the difference in the Etech and AI ?

[03' Big Red]

i did check the tag on the motor it is the AI 350, but it is also a 2003, maybe it was built late in the model year and got the 2004 engine ....

if i understand correctly tha AI/AC started in the 2004 model year.

[The Pits]

can the AI engines be converted to Etech?

[Tuffguy707]

i did check the tag on the motor it is the AI 350, but it is also a 2003, maybe it was built late in the model year and got the 2004 engine ....

if i understand correctly tha AI/AC started in the 2004 model year.

Are you sure its an 03? When was the build date? The reason I ask is If they are built in the later part of 03 it may actually be an 04 model truck. I am not sure exactly when Mack starts building the next model year. I may be wrong here though its just a thought.

[bbigrig]

We had received our first ASET AC engine in the summer fall of 2003. The emissions reg was moved up from 2004 to 2002 because of noncompliance charges from the EPA. (look it up) So basically any truck with a late 03 build was to have an EGR system on it. I know a few with AI engines that are still going with the same terrible fuel economy and lack of pull. The AC truck we received in mid 2003 was the first Vision with Volvo frame and AC engine (both frame and engine changed at the same time.

We could no longer order CH's because the AC engine didn't fit in the rails with that cooler hanging out. 2003 was the last year for the CH and the first of AC/AI engines. It was a Canadian test truck and it was a bag of crap. My own personal fleet would later have 4 ASET AC engines in it ranging from 04-06. We purged them by 2010. To many silly issues like belts and sensors.

[bbigrig]

The AI introduced EGR into the engine by bumping the exhaust valve open on each individual intake stroke. Less crap added on to facilitate EGR induction but caused performance issues. While the AI is very similar to the E-tech it's different pretty much down to the block.

AC engine has an EGR valve, EGR cooler and vane turbo with a wack of sensors. Lots to go wrong and was thrown together because they moved the emission date up 2 years.

The introduction of EGR is to lower in cylinder Temps causing lower amounts of NoX (Nitrous Oxides) into the atmosphere.

Our 2010 engines do it with less EGR and treating it down stream in the exhaust with urea. (what the Europeans have been doing without EGR for years.)

[chu613]

BBIGRIG

I'm pretty sure it was a bit different

Mack Vision was initially a CX and it went as a CX until 2006 when the Volvo frame was introduced and when CX became CXN.

CH was always available but not in a set back axle. CH also became CHN when Volvo frame was introduced.

Unfortunately I've never came across a CH axle forward with ASET engine and Mack frame, but I've seen CHNs with Volvo frame a bunch.

Look no further than CHN Rawhide

The earlier CX was a disappointment. I drove some in late 2004 to mid 2005. Pulling super B trains the temperature under hood would get so high that windshield washer fluid would boil in its reservoir. This was happening during hot summer days when pulling long grades or big hills.

Because of high temperatures under hood lots of components were failing like fan hubs, belts, hoses,wires,etc.

That's when Volvo frame came into play in 2006.

Wider in the front it allowed the engine to be dropped in between the rails and create more air flow, reducing under hood temperature.

With some other improvements, updates the CXN and CHN were way better trucks.

The first Mack I bought was a 2004 CX and I remember clearly the engine sitting high on top of frame. The EGR cooler was above the frame but it was there. Looking at a CXN the EGR cooler is way down and you can notice the space between the top of engine and air filter housing.

It's a clear sign that engine was dropped but the first Mack trucks with ASET engine were built on the Mack chassis

[chu613]

Another way to tell the difference between a CX with ASET engine and Mack frame and a CXN with ASET engine and Volvo frame is the routing of the pipe that connects the turbo and the inter cooler.

On the CX the pipe would go down outside the frame rail and connect into the inter cooler.

On the CXN it would have a more traditional way.

Pretty much horizontally from turbo to inter cooler

[03' Big Red]

I checked the build date on my truck 4/03

[bbigrig]

Another way to tell the difference between a CX with ASET engine and Mack frame and a CXN with ASET engine and Volvo frame is the routing of the pipe that connects the turbo and the inter cooler.

On the CX the pipe would go down outside the frame rail and connect into the inter cooler.

On the CXN it would have a more traditional way.

Pretty much horizontally from turbo to inter cooler

You are correct. I may be mixing trucks up. When you mentioned the charge air cooler piping arrangement I recalled they were different.

The test truck we had was the straight rail. The Volvo frame was before 2006. We had CXN's in early 2005.

[Mackdaddy2030]

So you were able to get an MP7 or MP8 in a late '07 truck with out DPF? That would be the setup to go with.

I hear if you deleted the emmisions on the new engines you will gain 1 to 1 1/2 MPG.

[Mackpro]

So you were able to get an MP7 or MP8 in a late '07 truck with out DPF? That would be the setup to go with.

I hear if you deleted the emmisions on the new engines you will gain 1 to 1 1/2 MPG.

In 07 you could get the CTP or CXP with a MP-7 with no DPF exhaust filter. No MP-8 option for that year. In 08 the MP-8 came out and it and the MP-7 came with the DPF exhaust system. The model names changed to the GU, CHU, CXU, MRU and LEU.

[Mack Technician]

On ‎10‎/‎18‎/‎2015 at 7:57 AM, The Pits said:

can the AI engines be converted to Etech?

Yes, you have to use a CCRS camshaft from 03. Remove and replace the restrictor exhaust manifold with a 1999-2003 manifold. Replace turbo with 1999-2003 of like-horsepower. They also make a 50HP injector that can be installed.  The attached bulletin shows which cam to use.....

Mack camshaft CCRS matches.pdf