A really big swap

[Tim Pringle]

Hi all! After some searching, basically coming up empty, I will post this thread & ask for advice & information from experiance.

The project? A 34 ft motorhome. Originally a 454 Chevy, totally burned up at 21k miles, then passed to me for a project. I have had experiance with building good running n/a 6.2 & 5.7 diesel engines, and have found some tricks (that many will argue about) that work well. I'd much rather take a chance for some better fuel economy than the 5-6 mpg I would get with that 454.

I have sitting in my shop a fresh '82 6.2 (stock) just itchin to pull that motorhome! I also have sitting right beside it a complete turbo system from a 1993 6.5 (the one with the spring loaded wastegate). Sure, it may be easier to go with a Banks system - for a price, but why when I have all the stuff sitting in my shop already? I'd much rather use that money for fuel, considering I have about 140 gallons of fuel capacity!

Ok, heres the stuff - I believe the engine will be turning 2200-2300 at 55 with the 400 transmission (I will sacrafice some economy for bullet-proof). I will be loaded, towing & climbing to over 10000 feet, which is the main reason for my maddness behind the turbo idea. Thin air = lost power & smoke, just when I really need that power.


My question(s) - boost - 10psi? What is the boost of the stock 6.5 wastegate? Head gaskets - Felpro? Or is there something better? Oil supply for the turbo - is the port for the oil pressure sending unit sufficient? I have seen the fuel pump removed & return the oil from the turbo there. I usually run an electric lift pump, makes filter changes much more pleasant. How about studding the block, or are the bolts sufficient? I have read at Banks to turn up the juice about 1/4 turn, use the pyro to see the temps. Am I on the right track? Would some type of intercooler be worthy of consideration in all this maddness?

It is my intention to keep costs down, in all respects, and mostly use what I have, and to keep things simple. Yes, I do plan to splurge for the vital boost & EGT gauges.

I am sure these are probably some of the most asked questions around, so please forgive me if this sounds like a worn out recording!

Ok, let 'er rip! I look forward to hearing from you!

Thanks in advance! Tim

[Robyn]

Well now
I really love the little 6.2/6.5 engines but here is my opinion.
The 454 was not nearly enough for packing a 34 ft coach around and was pushed to the limits.
The 6.2 even with all the tricks you can do to it is going to fall far short of the mark for hacking that kind of load especially over high mountains.
I rented a 26 footer back in 86 for a trip with my inlaws. This unit had the 6.2 in it.
The poor little critter just could not hack it.
I would not even recommend the 6.5 with all the best tech available to pull a 34 footer around.
These small GM diesels are best suited for pickups and utility vehicles. (Burbs and Blazers,Tahoes and such) that are doing light work. I can appreciate what you want to accomplish and also appreciate all the work that so many folks that come here have done to make the 6.2/6.5 better but the bottom line is that these engines simply will not hack the heavy stuff for any length of time.
My tow rig that I use to yank a 40 ft horse trailer around with is a 503 Cube
custom big block with 9.5 comp and as big a cooling system as I can get under the hood. a huge tranny cooler (oil to air with no in the radiator coils)
This engine is putting out HP and torque that the best 6.5 tubo could never dream of and live to tell about.
Its still marginal as far as Im concerned, We gross at 22,500 when loaded.
The truck is an 86 GMC dually 4x4 and it handles the load fine as far as being stable and all but the fact is that none of the drive train is really suited to this kind of work.
I had made a post earlier regarding tow rigs.
I will paraphrase it. If your going to tow get a business class truck designed to do the job.
If you really want to make that 34 footer get down the road you might want to think about a small Cat. Mileage will be OK but power will definately be there.
Just my humble opinion
Robyn

[moondoggie]

Good Day!

"I have sitting in my shop a fresh '82 6.2 (stock)..." It must be red then. Please ask around - there were issues with head gaskets leaking on the early red engines. Don't make the mistake I did. I had a red engine in my 82 & was told it was junk & to replace it with a black engine, late 83-on. THIS WAS BAD ADVICE - the red engine was actually cast with a higher-nickel content than all later engines until the latest one, recently released so is stronger than all 6.5 blocks until this latest block. When I 1st started here on the Page, this issue was discussed, & it's easily fixed. Try to get one of us that's savvy on these early red engines to explain to you how to eliminate this possibility.

I have nothing but complete respect for robyn - she's forgotten more about these engines than I'm likely to ever know. That being said, ronniejoe's 95 Sub pulled the hill this year within 1 mph of a stock 06 PS & a stock 02 DMax. He seems to be able to do this with no overheat problems. Isn't it possible an RJ-spec engine might not be at least adequate for this application? IMHO we can't all afford the proper pulling truck that robyn describes; maybe a 6.5TD could be built like RJ's, & just take your foot out of it a little (or a lot) on the bad hills? Something to consider...

Blessings!

[Robyn]

Doggie
Thanks for the vote of confidence.
I have been through so many pull rigs that I dont want to even think about any more trucks.
My whole point of this post is to point out that the 6.2/6.5 family is just not up to the task.
Sure I will agree that the 6.5 can produce some real power but for how long?
The hill climb is a great showing but its a short term thing.
A 34 foot motorhome is like yarding the Queen Mary around, there is no rest for the little engine that could.
I guess what I am trying to say without hurting this fellas feelings is the 6.2 swap is a Bad idea and is going to give him troubles down the road no matter how much love and attention he lavishes on it.
If the 454 which is a helava engine cant do the job without going to toast, AND MANY DID the idea of trying to do the job with a smaller less powerful engine is just beating ones head against the wall.
I can understand the economic reasons for wanting to use what you have, but what do you have down the road to show for all your work???
******Again I am not trying to hurt feelings and or sell something here I am just pointing out an area that may be of questionable returns for your labor

My 503 is a $6000 engine. And I did most of the work.
454 4 bolt block bored .030
open chamber small port iron heads New castings with stainless valves
steel crank ** 3/8" stroker
Forged steel custom long rods with 7/16 bolts
Forged custom aluminum stroker pistons 9.5:1 comp
Custom cam built by crane after a two week discussion on the specs I wanted.
Gear drive timing set.
Stainless steel headers with 3.5 inch all the way to the mufflers and 5" from the muflers out the back. Mostly for that look kewl stuff. sounds awesome though.
This beast puts out 590 HP and around 620 Lbs of torque and does it all at low to mid range where you can use it. My worry now is the drive train which was never designed to handle a monster like this up front calling the shots.
I have never worried about a TH400 doing the job but I do with this one.
Its terrible on mileage but it gets the job done. a 7% grade is no sweat with a gross of 22,500 lbs.
On a 100F day I can pull the grape vine out north of LA and the beast will not even break a sweat. Just have plenty of fuel on hand to feed that monster.
The secret is common sense and use the HP with care, NO MASHING IT FROM A STANDING START
I have been left on the back side of too many Mt's while towing and had all sorts of broken stuff to show for it. I most likely wont ever buy another tow rig. I dont do that much now that the kids are grown so the Old Jimmy will suffice. Heck with all the power its got it will blow off most current Hot dogs from the light.
Any way If your faced with no other choice on your project, give the little beastie every chance to live you can. Be sure to use a late high volume water pump and a serp belt drive system. A dual T stat system would be good too and as much fan as you can afford along with a Kennedy low temp clutch maybe even an electric booster fan too. Put as big an exhaust on the beast as you can get to let the heat out of the heads.
Dual tranny coolers would be nice with straight oil to air and nothing in the radiator at all. You wont have trouble keeping the tranny warm pulling this much weight around at all.
Loads of luck
Millions of miles and a zillion smiles.
Robyn

Aluminum intake with a custom rebuilt QJet carb.
Special aluminum cross flow radiator.

[gmctd]

I agree with all of you - solution?

5.9 or 8.3 Cummins, found in many a Ford, Dodge, IH, and etc trucks, lots of 'em are turboDiesels, and are a simple 3-wire installation - ground, power, and fuel solenoid from the IGN Sw.

They don't run hot, unless you're not taking care of 'em, they pull and pull in stock form, and they return good fuel mileage.

And they already are standard equip in a lot of the large motorhomes, so you won't be blazing any unexplored trails - meaning, off-the-shelf parts for the conversion, available wherever you dump your pottie.

The 5.9 is good for documented 700ftlbs torque with no damage, and the 8.3 is good for 1200ftlbs, every day, all day long, no sweat, G.I.

Did I mention Cummins?

Try it - you'll like it.....................

[Tim Pringle]

Thanks all for the advice, even though it may not really be what I want to hear. I will add a few details about what I have planned & what I do. The 454 in the motorhome was burned up mostly because the previous owner had neglected to put antifreeze in the radiator, so it froze & leaked water. They then drove it, knowing full well it had problems, and didnt bother to check anything until it quit moving. Huh...

I had definatly considered a Cummins - I own a 12v that I use to pull a travel trailer. I had considered an 8.2L from a schoolbus, but then you get into MAJOR mods, and end up hacking things to no end, and have a "Frankenstein" that no one will want to buy. This motorhome is built on the stepvan chassis (yea, the potato chip truck), and is very similar to a 1 ton truck. I havent actually weighed it yet, but I have been told it is around 10-12k LBS. I will load it. I will also tow an S10 or something similar behind it.

I know the 454 wasnt a powerhouse in stock form, although I could build it with enough grunt to twist the driveshaft in two. My past experiance with the 6.2 has been favorable. Picture an 82 'Burb that I converted to 3/4 ton from 1/2 ton, hung a set of 4.10 gears under, then proceeded to hook a 35ft travel trailer onto the rear bumper, loaded so heavy the tires looked low enough to generate a "sir, I will bring the air compressor over, your tires look low" conversation at the campground. I then proceeded to tow all this up a 35 mile stretch of mountain road, climbing 6000+ feet in the process with the NA 6.2, and got 14 mpg in the pull! And, add to that, it didnt run hot & I pulled in 2nd gear with about 1/3 throttle. I have broken 3 travel trailer frames in the last 5 years from the loads we haul! Man, do I sound like a lunatic missionary or what? Oh, I MUST add that I was able to keep right on the heels of a fellow missionary who was towing a similar rig with a 92 Dodge 4wd & a stock Cummins, giving it all he had.

Now, I will come clean - I DID a few mods to the engine, and I am SURE I will get arguments about some of them, but to be blunt - they work. I did open up the exhaust & added a cross over. I did add a non-egr manifold. I did NOT add a turbo. I did open up the air intake. I did do a port match & polish job on the heads. Yes, it was the red engine, and yes, the engine I am working on installing in the MH is red. This engine used the HD pump, and never did smoke, even at high elevation, so I was burning all the fuel. Well, it did smoke when I got to heavy on the drain oil in the fuel ( I can see the response coming on this one :) )& right foot. I'd burn corncobs if I could get them to flow through the fuel lines! I must also add the fact that this vehicle averaged 22-23mpg empty - well, also with 14 people & their luggage, 17 pulling the trailer on fairly flat ground & hit 26mpg (over 600miles on a single 30 gallon tank of fuel!) a few times.

I have to add this little usless tidbit of info that you 6.2 junkies will apreciate. While resting from a 36hour trip with about 3 hours of sleep to show for it, I had the opportunity to help a fellow 6.2 'Burb owner that had some transmission trouble. He directed me to the expressway while sitting in passenger seat. After the usual battle to get into the traffic flow & a little "puff" of smoke after a quick gear change, the look on this poor fellows face was priceless! I had to prove to him that I did NOT have this engine turbo'd! I have countless similar & useless stories, including putting a 5.0 Mustang to shame going up a hill :)

I dont plan to set any speed records, and I do know when to let off the throttle. I want to see if I can break this motorhome in half like the last travel trailer! I must mention the last trip up the mountains pulling the travel trailer with (sorry guys) my Dodge Cummins, and sitting along that long lonely pass at 3am with a sick child, myself not much better & a smoking wheel bearing on the trailer - 2nd bearing failure in 2 trips. All in the middle of central Mexico!

Am I a lunatic or what? So, back to the 6.2. I feel with a few mods & that little fan that will sit on one exhaust manifold, that engine should be able to run like a lightly modified 454. Am I anywhere near on the right track? Oh, in going back to my story on the 82 "Burb, I was a member here in 1998 when I was in the process building this beast - and was told then that most of what I did wouldnt work, and it was too much for that poor vehicle. This IS written from real cross country experiance. Please forgive my rambling and I AM willing to listen - again, I would like to hear from experiance.

Alright, back to you all - thanks again!

Tim

[ronniejoe]

Doggie
My whole point of this post is to point out that the 6.2/6.5 family is just not up to the task.
Sure I will agree that the 6.5 can produce some real power but for how long?


This 6.5 will run with any of them for any length of time you want to talk about. Until you've experienced it, you won't believe it, but it is true. I have a 32' travel trailer that puts my GCVW over 18,000 lb. when towing. I doubt that the 34' coach is any heavier.

I also haul water 3 - 4 times a week (550 gallons at a time on a utility trailer) at about 6500 lb. trailer weight for GCVW of around 13,000 lb. Comparing my truck now to when it was stock...night and day.

Bottom line: in stock form, I agree. The 6.2/6.5 is the wrong choice. However, the 6.5 TD can be made to run competitively to the new stock Diesels in pickups. It can be made to shove that 34' coach around with relative ease. It won't come cheaply, though. (Cheaper than a new coach, however.)

Yes, intercooling should be included in your swap.

[john8662]

Anyone else gag at all the gasser build-specs talk above?

I did!

Get enough of that elsewhere...

I think the 6.2 can do it, but you better get the HD radiator for a 6.2 or a 6.5 (there are two, you need the thick core one).

If you have the room in the chassis, then you might be able to squeeze the 6.5Turbo setup underneath.

Intercool that puppy!

The stock boost pressure for a mechanical 92-93 6.5 is 6-7psi, you'll want the Heath TurboMaster boost controller to crank that up to 15psi intercooled.

I'd find a set of 6.5TD heads for this engine build, so you can take advantage of the Diamond pre-cups, verses the smaller C/J cups in the 6.2 heads, although the '82 6.2 heads do have the larger exhaust valves.

Replace the head gaskets now, whatever you decide to do, the original gaskets WILL blow, especially under boost pressure.

Oh, and a new rear main seal to replace the rope seal too.

I'm sure there is more...

J

[Robyn]

This has got to be one of the better discussions I have been involved in for a while.
I tend to agree with RJ
"It Wont come cheap"
I still personally believe the 6.2 is going to be a downer for this application.
I respect all parties here and especially the owner for wanting to field his dream.
Best solution is to "Go For It" Give the little diesel rat all you can afford to put into it to keep it alive and see what happens.

[Robyn]

John
My apologies for the gasser talk. It is sort of sick isnt it?
Well after all the failures I had with the various new trucks I bought to do a fairly simple task (so I thought) I resorted, out of desperation to something I knew how to do to get the job done and not have any more costly failures.
After 4 trucks in about 3 years and none of them could hack it. (These were new trucks too not used rigs) I had had all of it I wanted and that was that.
As of late I have picked up on a load of new ideas that this wonderful place has provided and if this tech had been available to me back during the 1995-1999 time frame things most likely would have been different.
I am still of the mind set that the 6.2/6.5 engine family has a service ceiling if you will for doing heavy work and that it is reached far too easily on the stock rigs. Sure if $$$$$$$$$ are not an issue we can rebuild these little diesels to run like gang Busters and do it fairly well.
My Personal belief is that if a rig equiped with a 6.5 is kept to a Max GCVW
of no more 12K it will work sweet.
For example
Late model 2500 series Burb curb weight approx 7000#
towed weight 5000# = a perfect setup
Going heavier not only gets into an arena of too much towed weight versus the rigs weight but pushes the vehicles drive train beyond its design limits.
Now I know there is a dirt clod being hurled at me as I write this, and I have done things in my day that far exceeded the capacity of the towing vehicle.
As usual we use what we have to do the job.
My whole point in being involved is to offer many years of expierience and lord knows many failures and costly fixes for my ignorance up as food for thought to those who are looking for answers.
I just wish that GM would come up with a combination of truck and diesel engine that was Bullet proof out of the box without the need to wait 3-4 years for the aftermarket to come to the rescue and fix the thing.
Its not Just GM though. Nobody has done the job right. If its not the engine taking a poop its the tranny or the electrical system.
Seems that its always been this way so it probably wont change any time soon.
In closing I realize that all the combinations of ideas have most likely been tried and many have worked. My focus is "Long term" reliability and not just a quick sprint hauling the heavy load.
I guess my attitude stems from the fact that I run heavy haul trucks (105,500#) all day long for a living. I have my equipment set up to do the job and do it all day long year in year out. My current rig has just sailed past 600K miles with few down times. Maybe I expect too much I dont know??
Thanks guys for not firing the 16 inch guns at me.
I do love the company here and will continue to offer ideas and or spark controversy that will help further the cause

Tim please be sure I am not in any way trying to trash your ideas or any such thing. Keep thinking and looking at ideas.
I look at long term, cost effectivness and is it going to work when I need it to.
Nothing worse than having your vacation, horse show, car show or whatever ruined because the rig let you down. (been there done that)
Zillions of smiles
Robyn

[dieseldummy]

I'd tend to agree with the theory of the 6.2/6.5 not working well. No matter what, if the engine is turbocharged and has a decent fuel rate, it will overheat when pulling! That 34' monster will be to much in the mountains... I'd almost guarentee that. I don't care what RJ says about his "special" motor there are only so many things that can be done to a 6.5 and in the end they are still a 6.5... Like said above go Cummins or someting more in the medium duty category. IMO of course.

[john8662]

Putting a stock 6.2 in the hole probably isn't wise, as stated.

But...

Modifying this engine using ALL the available techniques will the be key to having a reliable engine to handle the stress of hauling that much of a load all the time.

I do believe that there is a key element missing from this equation. I do believe the fella building this rig will drive it conservatively only pushing it as hard as necessary. I'm a lot that way, carefully observing gauges, and only driving the vehicle as fast as it will safely go for the situation, even if it means being passed by nearly everything on the road pulling that heavy load.

Surprised Casey (Arveetek) hasn't chimed in, he pulled what I consider a big load all over the place with a n/a 6.2 for a long time, then turbo'ed the rig with a proper c/r engine and he's been doing quite well with it.

[ronniejoe]

I don't care what RJ says about his "special" motor there are only so many things that can be done to a 6.5 and in the end they are still a 6.5...

I remember someone making a comment about records wouldn't be broken... BTW, my truck doesn't overheat when worked hard any more either.

Now, personalities aside, what I've learned and incorporated has come from my quest to make my Suburban do what I bought it for in the first place...tow my heavy travel trailer well. I learned a lot from TDP, Kennedy and others who went before. The fact is, I've towed thousands of miles all over this country. Initially in stock trim and was disappointed. As the trek progressed, things kept getting better. My Suburban has 250,000 miles on it. Aside from the engine and torque converter, everything else is original (trans, rear diff, etc.). I believe that track record says the truck can hold up to heavy use. The warranty engine that I replaced last year went 160,000 miles (hard miles).

Right now, my Suburban pulls the best it ever has and handles my trailer in a dream-like fashion. I still pinch myself when I think back about what used to be. So, Robyn, this truck has done much more than just tow one 10,000 lb. trailer up one hill. I tow tractors, loads of hay, loads of water, loads of fire wood and anything else that comes along on a regular basis. It gets worked very hard.

[moondoggie]

Good Day!

"The hill climb is a great showing but its a short term thing." Unfortunately you don't know our RJ. If he can't break the motor he built & put in his Sub, it can't be broken. If you look at his three articles, in one it shows a picture of his gauges. He's showing us where his EGT, boost, etc. are when he's pulling out of Denver, but look at the speedo - he's pulling his 32' trailer 76 mph. I mean, really - how many folks have to weld in special floorboard reinforcements under their footfeed????? :eek:

The only place I differ with robyn is that I think there's a place for folks that can't afford what's the right solution, so do our best to "get by" with what we have or can get. I really believe that an RJ motor, towing with your footfeed somewhere short of through the floorboards, will probably last - he'll likely get my business if I ever have the need and actually have the money at that time. I've almost never had the budget to do what I wanted or what would be best, so I've done with what I had. Heck, I can tow with my stock 6.5TD's & be happy, it'll just take me a lot longer to get there.

robyn, take no offense, because certainly none is intended, but if I waited to do everything the best & right way, I'd seldom get to do anything fun. (I hope you're not offended - I/we can't afford to not profit from your hard-earned advice. ;))



Blessings!
(signature in previous post)

[Robyn]

None taken at all.
we are here to share and help each other.
I read the original post as "To Keep the cost's down"
I will agree 100% that if $$$$$ are no issue the 6.2 will make that 34 footer fly, well maybe not quite but anyway it would be possible to make a workable combination.
The key ingreidient here is $$$$$$$$$ RJ has spent the time and $$$$$$ to make his 6.5 work.
The stock 6.2 for the Motor home project is not the same critter. Tim has stated that he wants to keep costs down and I see us here comparing Rjs fire breathing dragon Burb to a stock 6.2
Anyway I do believe we are all pretty much on the same page and have given Tim some food for thought.

Tim you made mention that you did not want to make an Orphan or "bastard" by installing another engine type. Heck its done all the time. We have a fella here locally that has a 90 Ford 3/4 ton with a 3208 cat in it.
He thinks its PUUUUUUUUUUURRRRRRRRRRRRfect sorry I could not resist.
If you could opt for another engine combination it might be a thought.
I will sit back now and listen.
This has been a very honest and open discussion on a subject that will no doubt be hacked over again and again.
best to ya

Robyn

[wthif]

I havent actually weighed it yet, but I have been told it is around 10-12k LBS. I will load it.

I would like to say before my truck and engine under went a turbo I had a GVCW of 12,000 to 13,000 a couple of times. My truck got up to highway speed with out a problem and had some power left over. I will say that these were dump runs and soon as I got to the long slow sort of steep grade going into the dump my truck would start to overheat. I think the overheating was do in part to a fan clutch not working properly, but there isn't much room to spare when cooling a stock 6.2 and towing.

So my opinion a modified 6.2 could probably do it, but I wouldn't. Your motor home has one big disadvantage over my truck, wind resistance. Also I wouldn't have dreamed and still wouldn't dream of taking a load that heavy over 10,000 ft. I think for peace of mind I would put a modified 5.9 cummins in it place, unless you want to spend a lot of money on a 6.2/6.5. I would still like to see you try it and prove us wrong.:D

[moondoggie]

[font=times][size=+]Good Day!

robyn: I figured out where I went wrong

[moondoggie]

Good Day!

Tim: Any chance you can let us know what you decide & how it goes?

Blessings!
(signature in previous post)

[ronniejoe]

[quote=moondoggie][FONT=times][SIZE=+]Keep in mind, he

[moondoggie]

Good Day!

As usual, Ron, you're right & I'm wr..., ah wr..., - sorry, can't make myself say it. ;) He wants to tow an S10, which I suppose comes in ~ 3500 #, so unless his motorhome weighs more than 14,500 #, he's towing less than RJ. (I can't really say where I figured he was towing more than you do.)

Blessings!
(signature in previous post)

[kaylabryn]

I have a 27' motor home, it has an empty weight (no people or gear) of 12,500 and once you load all the essentials (spare parts tools food ect.) If I remember I was in the 14,000 range then I hooked a 14' box trailer behind me with around 2000 in cr@# in it. I had a driving weight of 18k with 4 people. So if you add 7' in length, the extra roof A/C and all that goes with a bigger home I think he will probably be in the 20K+ range with his s-10 in toe. You would be supprised at how quickly all that stuff you just have to bring adds up.

[Tim Pringle]

Hi all! I am finally back, after some interruptions. Seems a wife & kids have that ability sometimes.

Wow! I really appreciate the info. Seems there are some that think it will work & some who dont. I like this! Maybe this should become a feature article!

Ok, back to the project at hand. Robyn, thank you especially for your input. I can understand when someone runs equipment commercially - you learn the tricks of the beast. Hey, all, dont be too hard on her for suggesting to go with a gasser. Dont think for a moment this hasnt crossed my thoughts a time or two. Unfortunatly, I would have to do a complete & expensive rebuild, with the necessary mods to do it. It would never pay for itself in fuel savings.

I dont know of ANY motorhome in the 15-20 year age bracket that I could afford that is sufficiently powered, by either gas or diesel. Sure, the diesel pushers exist - for a price. About anything else in the 30-36 ft range will have a big block gasser. That doesnt leave many ready to go options. A travel trailer is nice, and very practical, until you add a 2 year old & a 2 month old to the formula. That can be kind of a drag on a 2000 mile trip, and you know, a child will ALWAYS get sick on the road! So, I will "drive the trailer & tow the truck"!

Believe me when I say I have considered most all of the suggestions mentioned above for optional engine choices. I have spent a lot of time with my head under the hood of commercial trucks & school busses with both International & GM diesel engines. Those engines are physically too large to fit without "rebuilding" the coach to accept them, then also the oil pans are different, motor mounts are different, add to that the weight. I almost had a 5.9 Cummins bought, but backed out of it when the injection pump went south. In measuring the Cummins, they are WAY taller than the 6.2 & 6.5, and wont clear to go in even as a short block, then I would have to build up the engine cover to clear - we are back to a "Frankenstein".

Then add to this formula that this coach uses a 400 with a brake drum on the tailshaft. Changing to an Allison from a school bus with a 366 gas may be an option - but I dont know if a diesel converter exists for this application. I had considered this for the extra low 1st gear. I could modify the Cummins & watch it spit out the Chrysler transmission in little bity pieces. Thats why my 92 Dodge with the Cummins is still stock. With the 5.9, an overdrive is a MUST, so we are back to transmission problems.

That really doesnt leave me with many options for an engine for this sled. I have done some research on torque & hp numbers for simple comparison. The stock 92 12v 5.9 Cummins in the Dodge sends out 160hp & 400 ft lbs of torque. The stock 454 gasser is 235hp & 360ft lbs, the stock 6.2 looks like 135hp & 240 ft lbs (about the same as a 305 Chevy, poor thing) The stock 6.5 puts out 200hp & 430 ft lbs, which is more torque & less HP than the stock 454.

I found an article in fourwheeler.com about a 6.2 4x4 Blazer build, and after a few minor mods, and the Banks turbo kit, they reported 172hp & 451 ft lbs of torque. I seriously doubt they pulled the heads & did any port matching. The ports & gaskets on that 6.2 are a disaster!

I am in the process of pulling the heads of the 6.2 to do some head work. Only a lunatic would pull the heads off any freshly rebuilt engine! Just to know, it has been bored out .030 with new pistons, new cam, 10-10 crank, valves & all the usual stuff. It is FRESH. It has only run a few hours on the stand - the by product of someone elses failed project. It was purchased right!

One mentioned wind resistance - this motorhome is the 'shark nose' style, and has some pretty wind splitting features. Most of you are expecting the engine in your truck or 'Burb to run 200k without any major problems. How many motorhomes do you see with that many miles? Most are retired with around 50-80k (look at the used adds in the trader mags). I would probably put around 5k on this coach per year, so 50k would be about 10 years worth of use, and it is likely I will have used up the body before that time (remember, I have broken several travel trailer frames in my work).

Some other factors to consider in my maddness is that I will be climbing once a year, loaded about a 35 mile stretch of mountain that is fairly steep, coming back will be mostly down hill & empty. The rest is on fairly flat ground with some smaller grades. Also consider the cost of diesel fuel in Mexico, an advantage I will have at a whopping $1.60 per gallon! And, the capacity to haul enough fuel out to make it back to my home in Illinois without fueling once I leave Mexico!

Now, some info on my older rig. The trailer I used to pull weighed out at around 10k lbs loaded, I am guessing the 'Burb to be around 7k, and about 1000 lbs of stuff in there too. That would be around 18k I was dragging up the side of that mountain. I did NOT have problems heating up. I also didnt set any speed records. About 20-25 was tops in the climb, and the rest of the trip into Mexico was around 45. I found on flat ground about 50-55 was tops, anything over that would get squirrly because of the weight I was hauling. Remember, this was a N/A engine with some massaging on the heads. I am content to "get there with my equipment intact" rather than trying to get there fast.

I already have a new 4 row radiator ordered for the coach, as well as planning a large trans cooler & air to oil cooler for the engine oil. I do have a complete '93 6.5TD, but it will need rebuilt, and one of the heads is damaged (seat beat out of 2 intake valves), but would have the higher po pre-chambers. It would likely take a bore & new pistons to fix (#8 is loose), but intact.

I am sure I have cluttered up enough space, so I will quit. I do need to ask Moondoggie what gears you are running in your 'Burb, and is it a 1/2 ton or 3/4 ton? Ok, back to you all - I am listening:)

Tim

Ps: The coach has 4.88 gears & 33.5" tall tires

[DmaxMaverick]

I'll probably get beat up for this, but I'll say it anyway....

If I were in your shoes, I'd do exactly what you planned to begin with, minus the 400. A 4L80E (stand-alone) or Allison 545 would be a much better choice. If a tranny change is not an option, I would run the 400. A 2 speed rear axle may be another option with that, and you can get them for cheap. A Gear Vendor would cost as much as a 4L80 upgrade. Turbo or not....The turbo will only gain speed. N/A, let the gearing do the work, just not as fast, and fewer parts to break. You are right to consider reliability vs. speed in your situation. The 6.2 will run against the governor all day, if you keep it cool, and like it. Noisy that way, but it will get the job done, and be ready for the next day. An added bonus, it will return good mileage overall, and is very tolerant of questionable fuel quality. I wouldn't even consider an electronic IP, where you are going. A Mil-Spec DB2 would be ideal.

In your situation, you'll do better to be the tortoise, not the hare.

[Robyn]

Dmax
Sounds like some sound advice to me.
I personally would stay with the 400. Its a better box overall and will return more miles with less headache. The gear vendors would be a nice touch or as you mentioned a two speed rear axle. getting the terrific load off the 6.2 will surely give it a break and allow for some good life.
When GM reworked the 400 to include the OG and the lockup they used a lot of 400 parts but as is usual they forgot some good engineering in a few places. The 400 with a good cooler and a modest shift kit will be almost indestructable behind the little diesel rat. use a HD diesel torque converter built for motor home use and be sure it has 6 bolt flex plate.
Hmmm this just might work with the lower gears and just let the engine run along.
Tim please keep us posted as to what you decide to do

[DmaxMaverick]

I do agree about the 400, but I was trying to work in a lockup TC and/or OD. The 6.2 has sufficient torque to keep that weight tooling along on flat ground at lower RPMs. I mentioned the 545 because they can be had reasonably, will adapt well, and have more, shorter gears (not to mention bomb-proof). A 2 speed RE can be had for that chassis as equipped OEM, and wrecking yards are full of them. Personally, I'd opt for a manual tranny, but he hasn't so much as mentioned that as an option. With a granny low, and a 2 speed, you'd have the best of the best under the circumstances, but you'd have to hand-shake.

[ronniejoe]

Hmmm... I have a 4L80E that has nearly 250,000 miles on it completely stock. Many of those are running power levels that few 4L80E's see. I replaced the torque converter at 214,000 and that's it. Pretty bullet-proof if you aske me.

Since I worked for GM and frequented the Tech Center during the time of its design, I can tell you for sure that it is a revamped 400 with an extra planetary set.

[moondoggie]

Good Day!

"I do need to ask Moondoggie what gears you are running in your 'Burb, and is it a 1/2 ton or 3/4 ton?" Our Sub has 3.42 gears. It says 1500 on the side, but the only difference between our Sub & a 2500 is the rear end is a semi-floater 14 bolt (2500 is full-floater 14 bolt), & its GVWR is 8050 (2500 is 8600). RJ thinks my frame is thinner than his 2500, but he hasn't yet told me where to put the caliper to clarify this.

I missed how you even know I've got a Sub - I forgot to leave my signature on any of my previous posts (corrected here).

BTW, I pulled a friend's tractor from the metro area to his horse ranch earlier this week. It's an International 2500A, which is the industrial version of a 574. It is listed as weighing 4800 #, but I'll bet that's without fluids. I think it probably came in at 7000 # or so with the loader, cab, & all fluids. I pulled it on a tandem axle 8 x 20-something ft trailer, so it was well up in the air. I pulled it with the Sub at 65 mph ~ 100 miles in OD, returned the trailer to the rent-all, & got 13.1 mpg in the deal. I'm not unhappy. It dealt with the puny "hills" on hwy 169 OK, but would have been in serious trouble in mountains.

I couldn't figure out why you were interested in the gears in our Sub, so I thought you might be interested to know that our 82 has 3.08 gears. That, with the 4 spd manual w/ OD tranny, made some terrific mpg numbers.

Blessings!

[Robyn]

RJ
I have had 3 Burbs that have or had the 4L80E in them. The first was a 95 with a 454. we put over 200K on it and not any issues the second and third ones are 94's that we currently have and they are both 200K plus.
I have been inside a few 4L80's and am not impressed with some of the parts they are using. Granted they seem to do the job but I feel the 400 is a better box for the heavy duty application.
I will come clean and tell you why.
Electronics will fail its just when!! Every time I have had a breakdown that left me stranded needing to get towed in it has always been electronics failures.
If there was a way to make the 4L80 a manually run (Hydraulic shifted) box I would scream with joy and jump up and down. I would have a garage full of them.
On my Hummer kit project I really wanted an OD and a lockup converter to get good highway mileage.
I spent a Buttload of $$$ on aftermarket parts and goodies to build a killer 700R ( Not counting my bench time) Now the 700 is in no way a mate for this Motor Home project but it will live for my use and it wont lose some electronic junk and leave me stranded.
My kingdom for one of two things, a new truck that you can fix with a srewdriver and some small tools, (like we used to be able to do) or a new trucks with dependable electronics.
I am not holding my breath!! :0)
Seems of late if its not a module, relay, pcm, or some stupid electronic goodie failing its a flat tire. Heck I can fix the flat in the rain along side the road with minimal tools.

In all fairness the 400 with a Gear Vendors would be bullet proof.
best to ya
Robyn

[Tim Pringle]

I will most certainly keep you all posted with the progress on this swap. I hadnt thought of a 2 speed rear axle. I didnt know if they were an option on this chassis. I will have to do some checking. I had considered a Gear Vendors over/under drive unit, until the price of around $3000 made me wilt! I had also checked US Gear, which is a little less expensive, but is more or less manual. Know of any others that may be more affordable?

I feared the 700 r4 wouldnt be a good option for this rig, then we are back to the brake drum on the rear of the transmission problem. I really want that extra brake, esp if I get stalled out on the side of a mountain. I have been looking at the Allison from an older Chevy powered schoolbus, and think I can make it go with some mods to the subfloor pan (mainly moving some insulation & small braces around), but I dont know if I need to change converters for the diesel, or if there is an adjustment for the line pressure to adapt it.

A couple of points I didnt make earlier, which points me towards the diesel over the gasser, is having towed this same pass with a gasoline powered truck, I found that I needed to stop every so often while climbing to adjust the ignition timing. Coming back down it was the same thing, only in reverse, it would start spark knocking because of the poor quality gas & advenced timing. It was non - computer engine. With the diesel, ya just drive it. The other is I want the turbo to help burn the fuel at higher elevations. It may be necessary to get things moving on a grade, and the turbo will provide the boost to get my rpm's up. We almost got stuck once when we had to stop going up a steep grade driving a fairly "hot" gasser - the engine would come up to the stall speed of the converter & just sit there. It wouldnt go! We finally managed to lay into it & hold it - it finally began to move! Oh, the stories I could tell about this work!

Moondoggie, I just asumed you had an '82 'Burb from reading your answer to one of my comments. Maybe I should ask about your truck instead. The 'Burb I ran back then used the 700 auto trans, had 4.10 gears, the heavy 3/4 ton floater axle & a lightly modified 6.2. I felt 26mpg was pretty good for this setup, considering I could tow about anything I could hook to the rear bumper:) No offense intended.

Now, with a few details to work out & I am sure a few questions to throw at all of you, it is time to prove if this will work or not. There is only one sure way to tell - and sitting here on this computer isnt going to prove anything. Time to turn some wrenches!

Any additional thoughts, ideas & comments are welcome:)

Tim

[3and3oneton]

You might check Advanced Adapters for a gear splitter. I purchased their ranger overdrive for significantly less than what you quote from gear vendors. Mine was for a manual transmission, but I believe they offer it for a wide variety of trannys. Good luck.

[moondoggie]

Good Day!

[i]I pulled it with the Sub at 65 mph ~ 100 miles in OD

[rustyk]

As someone previously posted, that 34' motorhome is going to weigh in somewhere around 20K lbs.

I have a '94 Barth 28' diesel pusher on a Spartan chassis with the 6.5L TD (mechanical FI). I've done the Kennedy Diesel cooling upgrade and the Mag-HyTec trans pan and diffy cover....cooling equals longevity.

At 15.5K #, my coach isn't overpowered, although it's really only taxed on 7-8% grades - I can maintain 45-55 mph on 5-6%.

I'm with those who suggest that the performance results with the 6.2 would be disappointing for the efforts and expense involved. A friend of mine had a 34' with a 190HP Cummins 5.9L, and it was just plain weak in the mountains, although the reality is that any but the top-line coaches with 450HP are going to crawl in the hills.

And as has been mentioned the frontal area on a motorhome makes the drivetrain work hard all the time. The sharknose won't work any miracles (Barth made a version like that, and there was no difference in mileage).

However, there's on way to find out the results - do it! :D

[arveetek]

Surprised Casey (Arveetek) hasn't chimed in, he pulled what I consider a big load all over the place with a n/a 6.2 for a long time, then turbo'ed the rig with a proper c/r engine and he's been doing quite well with it.

I've been reading the posts in this thread, but I couldn't decide for sure how to respond. There are different schools of thought on this forum, and most of them lean towards "if you're going to do something, do it RIGHT." Unfortunately, that involves spending gobs and gobs of money. For example, I would probably never spend the money for splayed mains....while it would make a very reliable 6.5L, by the time you spend that much money, you could have bought a 5.9L Cummins and be done with it.

So, since Tim already has the motorhome and already has a 6.2L, it seems to me to be a no-brainer: go with the 6.2L! He knows what to expect out of it, so I don't see a big problem. I pulled a 29' 5th-wheel many, many miles with my n/a 6.2L, and I was pretty happy with it. Now that I have a super turbo 6.2L, I'm REALLY happy with it! Yes, that motorhome won't break any speed records, but the job will get done, and get twice the fuel mileage doing it.

Casey

[Robyn]

I agree with the statement about crawling in the mountains.
I had done a Bus conversion some years back. I had an MCI-9 coach I bought from Grey Dog (Hound) and it had a tuboed 8V92 in it. I had set that thing up with some big squirters and it would lay out a cloud of black smoke and haul tail over the mountains. I dont really know what the old girl weighed loaded. It was a 40 ft highway coach with all the good living quarters in it.
carried 60 gallons of propane,100 gallons of fresh water, 100 gallons split between gray and black water. 250 gallons of diesel. 12 KW gen set.
It had an allison box in it, at this late date I cant remember which one. I think it was a 740 but wont stick hard on it. I had a GM coach before the MCI that had a V730 in it with an 8V71 detroit.
The larger factory "production" motor homes tend to be a tad wanting in the power dept. for sure.
One thing about the Cummins 5.9, it may not be a rocket but it will stand up to the task and grunt all day long trying.