Cat C7 Replacement?

[jofred99]

I'm looking at a bus that has a Cat C7 power plant, but would like to look at the worst case scenario. Like what happens if the engine dumps on the highway coming home from the bus yard. While the C7 would be the easiest for replacement, there are a couple of other power sources (DT466, Cummin 5.9/6.7) that I would prefer.



The tranny is an allison 2000 series, so the question is: What engines can be put into the bus (it's an '05 Freighliner) that would be a reasonably easy to swap? It's a mid sized 8 window bus.


Can a mechanical engine be mated to the Allison?

[cadillackid]

while engine swaps can be done from one manufacturer to another.. treat it as a completely custom build.. there will be no such thing as a "bolt in".. if you have experience fabing and building then you can do a swap of another brand...



allison 2000s can be mated to mechanical engines with the right TCM and a mechanical throttle box.

[musigenesis]

Originally Posted by jofred99

I'm looking at a bus that has a Cat C7 power plant, but would like to look at the worst case scenario. Like what happens if the engine dumps on the highway coming home from the bus yard. While the C7 would be the easiest for replacement, there are a couple of other power sources (DT466, Cummin 5.9/6.7) that I would prefer.



The tranny is an allison 2000 series, so the question is: What engines can be put into the bus (it's an '05 Freighliner) that would be a reasonably easy to swap? It's a mid sized 8 window bus.


Can a mechanical engine be mated to the Allison?

If your engine dies on the way home, you'd probably do better financially to junk it and get a new bus.

[FamilyCircus]

Last C7 repower to a Cummins ISL9 cost 35,000

[musigenesis]

Originally Posted by FamilyCircus

Last C7 repower to a Cummins ISL9 cost 35,000

Correction: OP would do better to buy 10 buses and keep the best one.

[banman]

Originally Posted by jofred99

I'm looking at a bus that has a Cat C7 power plant, but would like to look at the worst case scenario. Like what happens if the engine dumps on the highway coming home from the bus yard. While the C7 would be the easiest for replacement, there are a couple of other power sources (DT466, Cummin 5.9/6.7) that I would prefer.



The tranny is an allison 2000 series, so the question is: What engines can be put into the bus (it's an '05 Freighliner) that would be a reasonably easy to swap? It's a mid sized 8 window bus.


Can a mechanical engine be mated to the Allison?

A 3126 should bolt right in, basicly the same 7.2l engine with a little less to go wrong on it... The 3116 is the more mechanical version of the 3 engines.

Having done engine/re-power swaps on jeeps and scouts. It's only harder on something bigger and heavier...

*unless you ENJOY this type of a$$-pain don't a bus that doesn't have the drivetrain you want. A big diesel engine worth buying won't be sold cheap -- unless it's already in the bus you bought...

[juliol]

Banman, I have a 1962 scout what engine swap do you recommend that is simple and not mayor mods? sorry to go off the issue, but I read scout and could not hold myself.

Thanks

[wrenchtech]

Originally Posted by juliol

Banman, I have a 1962 scout what engine swap do you recommend that is simple and not mayor mods? sorry to go off the issue, but I read scout and could not hold myself.

Thanks

Mercedes OM606. They came in 1996 - 1999 Mercedes E series cars in the US, but were widely used in Europe. Mechanical pumps are available that will allow them to be tuned to make 500hp. Stock they make something like 175hp and 275 ft lbs, which would move your Scout quite nicely. DieselPump UK has everything you need. Or if you have $15,000 to spend on the project, you could get that new Cummins 2.8l crate motor. Axis Industries is a leader on solutions involving that motor.

[banman]

Originally Posted by juliol

Banman, I have a 1962 scout what engine swap do you recommend that is simple and not mayor mods? sorry to go off the issue, but I read scout and could not hold myself.

Thanks

PM sent...

[jofred99]

Thanks all! I'm still wondering about the C7 and wanted to see if there were other options.

[wrenchtech]

Originally Posted by jofred99

Thanks all! I'm still wondering about the C7 and wanted to see if there were other options.

I am interested in this question too. I have a 2008 Thomas bus with a cat C7 and I have been thinking along the same lines. There's not that much on the Internet about swapping engines in school buses. I have to believe that it's not as bad as some of the other contributors to this thread are making it out to be.

There is a company called Custom Automatic Conversions, that works with Allison transmissions for the pickup truck crowd. A lot of those guys want to swap Cummins engines and Allison transmissions in to pickup trucks. The first thing Custom Automatic does for an Allison swap, if the transmission is out of a Chevy or GMC, is to delete General Motors transmission programming and replace it with real Allison programming from the medium duty truck world. They create Allisons that run standalone all the time. I know that their programing works with Allison 1000, 2000, and 2400 transmissions (which are almost identical in their main structure).

Now the C7 engine seems to be a completely different beast. There are two generations of that engine. The later generation, which came out in 2006 and ran to 2008, abandoned the long running HUEI injection system in favor of a common rail injection system. I am certainly no expert on these engines, but I would venture to say that at this point the caterpillar C7 engine is little different than a Cummins 6.7. Both engines have common rail injection, variable geometry turbocharger, catalytic exhaust emissions equipment, and EGR.

The big difference is that the Cummins 6.7 has been analyzed and modified until there is no secret left unexplored and there are a thousand aftermarket experts ready to make them do whatever you want. On the other hand, there are one or two people in the whole country who know the ins and outs of the Caterpillar electronic engine controls and who will work outside of the official Caterpillar system. I found one guy who will help you delete some of the emissions equipment and tune for slightly more power. Last I heard he was asking about $3000 for that service. Even if I could spend that kind of money, I don't think that I would want to be at the mercy of that one guy, who is here today and could be gone tomorrow, leaving you with an engine that nobody can work on.

If more people became familiar with hacking the caterpillar ECM, I don't see why the C7 couldn't be an excellent engine.

Now let's consider the state of the Cummins aftermarket for modifications. A 2003 - 2006 5.9 common rail engine in a Dodge truck puts 280 hp to the rear wheels and about 550 pound feet of torque. With only a re-programming of the ECM that same motor can put out about 450 hp and 800 pounds feet. I'm not saying that that's what you want to do in a bus, but just that it's possible. With the Cummins 6.7 a lot of folks want to get rid of the variable geometry turbocharger. The ease with which it can be done makes it appear to be an almost trivial undertaking. I know that Gale Banks has been working with the Cummins 8.3 in RV applications, but beyond that I know nothing about the 8.3.

So ditching your caterpillar engine in favor of a Cummins swap looks pretty good. Again, I am no expert, but I am thinking that if you can get your Allison automatic to run as a standalone, which appears to be no big deal, why not put a Cummins in front of it? If you use a 5.9 or 6.7 from a dodge, you could easily get a wiring harness and ECM to run independently of the rest of your truck/bus. As far as getting the engine physically installed, there are an abundance of parts, motor mounts and transmission adapters and bell housings available at wrecking yards to make it a bolt-in job. Basically the same job that people are doing every day in pick up trucks, so why does everybody say this is so horribly expensive and difficult?

[Ronnie]

It really depends on your skill level as well as what equipment you have available to lift engines, transmissions etc, and the work space to do it.

as for replaceing the 300hp cat in your bus with the smaller 5.9 or 6.7 cummins, I would not even though it can be turned up to the same or more power it is a small engine working harder to do the same thing. I would be looking at the 8.3 instead. Or the Mercedes that was an option in your bus. It is always easier to swap if you stay within what was offered as options

[wrenchtech]

In the mid-1990s I drove a Ford L 8000 expediting truck. It had a 60 inch high-rise sleeper and a 25 foot cargo box. It was powered by a 5.9 Cummins that was rated at 210 hp. I drove it in an over the road regional expedited freight hauling operation. I was putting roughly 60,000 miles a year on the truck. Other than regular maintenance, I never had to do anything to that engine. It wasn’t a fast truck and you never wanted to be climbing a hill with a load, but it ran and ran without any problems.

[Ronnie]

I am close to 400,000 miles on mine in a pickup that is always pulling heavy trailers, up to 26,000lbs. So yes a great engine, and many buses have them. I still would not replace a larger engine with one though.

[wrenchtech]

Just doing a quick search, I believe I have learned that the caterpillar C7/3126 long block weighs about 1100 pounds, same as a Cummins 5.9/6.7. If this is true, then it would be hard to characterize it as a bigger engine. The Cummins 8.3 weighs about 1800 pounds, so it is certainly bigger. The more I look at it, the better a 6.7 Cummins swap looks. And remember, stock horsepower and torque ratings on some versions are close to 400 hp and 1000 pound feet

[EastCoastCB]

3126 totally dry weighs 1250 lbs.

I've driven buses with 5.9's and 3126's. 3126 is my choice.
You logic sounds ok if talking about hotrodding pickup trucks but a 400 hp small cummins isn't going to be a very good engine for a bus in terms of longevity.

Hp isn't really a helpful figure in buses. Torque is everything.

[WIbluebird]

You need to realize with the limited cooling capacity on the rear engine buses you really can't get away with turning up the power very much. A 6.7 is going to be working HARD to get a 38 ft pusher going and cranking up the injectors is only going to make it run hotter. Plus you also have to reprogram the transmission to handle the extra power and I've literally never heard of anyone that offers custom tuning solutions for the Allison MD3060 or 2000 series.

I don't really see the point of pulling a perfectly good-running C7 and going through all the headaches that swapping motors on these electronic buses come with. Unless you get a donor bus with perfectly matched wiring harnesses or jam a mechanical Detroit 2 stroke or 12 valve in there it's going to be an eternal PITA with lots of expensive trips to dealers for reprogramming.

[Ronnie]

Let's look at this differently. The problem is a concern about reliability if the C7 engine correct?

Are you aware Cat has a retrofit kit fir the HUEI system with an extra filter ? This is what might be considered "bullet proofing " for the C7. I am sure it is not cheap if you have Cat do it. But certainly cheaper then changing engines. Just something to consider.

[banman]

Originally Posted by Ronnie

Let's look at this differently. The problem is a concern about reliability if the C7 engine correct?

Are you aware Cat has a retrofit kit fir the HUEI system with an extra filter ? This is what might be considered "bullet proofing " for the C7. I am sure it is not cheap if you have Cat do it. But certainly cheaper then changing engines. Just something to consider.

To piggyback on that thought -- if your C7 is high hours. INVEST in a new HUEI pump -- if you can take your time you can probably find a good low hours or even nos unit sitting on someone's shelf...
(this will be my plan for my 3126...)

[wrenchtech]

Well then, as I said a few posts ago, a second generation C7 with common rail injection instead of HEUI must be a pretty good engine.

I would love to find somebody who can reprogram the ECM on my second generation C7 so that I can replace the variable geometry turbo charger and delete the EGR and exhaust catalytic converter. That would really be the way to go.

If some cat C7 (2nd gen) owners would pool their resources, they could probably hire an engine controls expert to write the programs that they need. But I guess I’m being unrealistic, because many Skoolie people seem to be the type who want to buy a bus at auction for $1200 and drive it until it breaks and then junk it. The pick up truck community on the other hand seems to have quite a few people in it who are willing to spend $60,000 on a truck and another $20,000 for upgrades.