Cummins Swap????

[SANDMAN500LT]

I have a 93 crew cab with a 6.5t....I recently purchased a LARGE 5th wheel and I need more power....I would like to do a Cummins swap...The truck is equipped with a 4l80 trans which is my main concern...Will it work with the existing TCM or will I need a stand alone?....I have allready located the bellhousing adapter and motor mounts as well....

Has anyone else done this conversion that could give some advise???

Thanks............Tony

[Diesel Dan]

It can be done with the stock TCM. Don't know all the specifics but while I was trying a cummins 5sp swap a zone rep for cummins was doing a cummins/4L80E conversion in his truck. IIRC, it was a '92-93 as well. He had to rig up a TPS and RPM sensor. Problem I seen with the GM adapters was it clocked the motor about 10* counterclockwise, as seen from the front. This created more interference with the oil pan/front diff on the 4wds.

[tom.mcinerney]

There is a classic writeup somewhere on this site [maybe search Members' or Dr Lee's for "DogDiesel"]. DogDiesel has done it...well.

[moedog]

HELLO, IM DOING A CUMMINS CONVERSION SOON. HAVE BEEN STUDYING THIS FOR 3 YEARS. THE 480 AUTO HAS A WEAK SPOT IN THE MAIN SHAFT WHERE THE OIL HOLE IS AND A CUMMINS WILL SNAP THIS SHAFT. THE ONLY WAY TO AVOID IS GO TO THE NV4500 OR NV5600 6SPD MANUEL WITH A STRONG CLUTCH WHICH IS WHAT IM DOING. IM USING A SHOP IN MONTANA WHO HAS DONE OVER 300 CONVERSIONS IN ALL TYPES OF VEHICLES.
HOPE THIS HELPS
DAN

[Arlie]

I've given this serious consideration as well. I'd sure like to put my money into more of a bullet proof diesel. Then I thought about the hours of work and how I'd feel if it got smucked. :eek:
If the process were laid out in black and white so one could be confident going in with an idea how much time and money the decision might be easier. I did gather some bits and pieces of info.
I know it's a lot easier with non-computer engines (can't recall what year computer starts) and some frame mod for the ps pump is needed. Maybe rad relocate for intercooler or find other location?
If someone put together a good manual they could likely sell a few. smile.gif

[SANDMAN500LT]

Thanks.....let me know how it goes....I am also conidering the maual trans swap....Mainly for computer reasons but I certaintly dont wanna spend $3k on a tranny just to break it.....

[SANDMAN500LT]

I researched the "DogDiesel" post.....He did a fine job of descibing the whole process in great detail...He also did the swap after owning a 300hp 6.5 and seems pleased with his decission, plus his cummins is only mildly turned up..

[More Power]

Since the spring of 1999, the 6.5TD Power Project (http://www.thedieselpage.com/finale.htm) has accumulated nearly 155 thousand miles and counting. There has not been been a single issue with the engine or marine DB2 fuel injection system. Still starts (hot or cold), runs and performs as well as it always has.

MP

[rjschoolcraft]

The 4L80E is tough enough to handle the Cummins. It's better than anything Dodge has put behind that engine.

I agree with MP. For less money and effort, you can get performance out of the 6.5 that will rival anything offered today from any manufacturer in stock trim.

[SANDMAN500LT]

Dont get me wrong...If I thought I could get enough power out of the mechanical 6.5 to adequitly pull my 16k fifth wheel up steep grades, I would do it in a second....

Part of my decision was based on the "pull off" results....From what I can tell, JKs very modified 6.5 didnt fair as well as the bone stock duramax on the hill...(also just assuming JK's 6.5 is about as hot as they come, correct me if im wrong)

I know the modified 6.5 will definetly win the drag race and be alot more driver friendly than the cummins but im concerned about spending several thousand dollors on the 6.5 and being dissapointed in its pulling performance...

Help!....Help!....Help!.......what do i do?

[cruzer]

A friend of mine has a 2000 cummins dually 5speed 4x4 and I can tell you it feels like it has more than my mod'd 6.5. I'm faster empty though.

I can also tell you my mod'd 6.5 is like a different truck compared to stk 6.5 w/exhaust.
It has awsome power now. I used to have to push the truck hard to keep speed, now its just cruzing down the highway w/the same load.

Figure mod'd 6.5=close to stk cummins
Mod'd cummins=even more

[SANDMAN500LT]

cruzer,Are you running low comp pistons? How much boost?

[rjschoolcraft]

I happen to think that you can. My mid range power and torque beats a Duramax, but tapers off at the top end. The tapering off is related to the turbo charger, in my opinion. If you havn't seen it, look at the dyno data from my Suburban at Schoolcraft Power Train (http://www.schoolcraftpowertrain.com/index.htm) on the web or read through my 6.5 Performance (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=006650) post and study the results. If you compare my time at the hill climb, I was within 1 second of Kennedy with a heavier trailer. I believe that I could have made 48 or 49 miles per hour if I had shifted out of second into third. I'm wishing now that I had made another run or two to get the technique down. I really think that I've only begun to get the potential out of the 6.5.

[More Power]

A 1999 6.5TD 3500 dually with 4.10 gears is factory rated to pull a maximum trailer weight of 8,500-lbs. Some factors that determine maximum GVW and GCVW include engine power, braking capacity, and items like frame, suspension and axle design.

The current Duramax powered 2500HD/3500 pickups are factory rated for a maximum of 22,000-lbs combined truck-trailer weight. When choosing a 16,000-lb trailer, that leaves just 6,000-lbs for the weight of the truck, passengers, luggage and fuel. The lightest Duramax is a 2WD standard cab, which will just barely squeak under the factory GCVW rating with a 16,000 lb trailer.

A 4L80-E is factory rated for 440 lb-ft of torque. Survivability becomes increasingly suspect at higher torque levels. Of those I know about who have installed a Cummins in a GM truck have all boosted power beyond the 4L80-E's ability to cope.

I know of one member here in Montana (Dave Hartman) who paid for a Cummins conversion (10K$) in his 1994 K3500. He's now on his 3rd NV4500, due to its inability to handle the power when towing heavy. Amazingly, the NP241 transfer case and 10-1/2" FF rear diff are still original. He can't install an NV5600 (besides being another 3K$) because the added length puts the transfer case right on the torsion bar crossmember. I suggested be pull back on the power, but he just can't force himself to do it.....

If I were hell-bent on a conversion, I'd install a Duramax/Allison. This can be done for about $7500 if the owner provides the labor.

Most people who tow reasonable rated loads would do well to keep the 6.5. We've proven the 6.5 can do the job, and do it for many years and hundreds of thousands of miles.

Lastly, if I just had to have a Cummins, I'd get a Dodge pickup. They're cheap to buy and plentiful.

Just my humble opinion....

MP

[cruzer]

Sandman, I am running stk pistons and about 14-15psi boost on a pull up hill, flat is somewhere around 10psi cruzing. I run up and down I-75 thru the hills of KY. B-4 mods I would have to downshift early to try to stay above 55 on some of the hills. I always try to run about 72mph+. Now I run cruze control all the way down, w/minimal fluctuations when pulling hills. Big hills I may lose 5mph, maybe a little more w/the cruze on. No downshifting required, either by the truck or me. The truck will automatically downshift at 60mph. I have a 2000lb slide in & a Toyota Landcruzer on a trailer along w/parts for breakage. All totalled approx 8000lbs plus a 6500 pound truck.

I am running the stk GM1 turbo also. I will be
putting on a GM8 in the near future. My pump is turned up only 1/8turn too. I will probably go another 1/8 because EGT's are still low, but will wait to do that after the GM8 is installed and I see where the EGT's are at. Another words I believe there is still room for improvement.

I'm w/ More Power If I were to own a Cummins it would be in a Dodge.

Have you done ANY mods to it yet? My 1st mod was the banks stinger system, B4 I knew about TDP. It was good but instead I'd get a 3.5"-4" exhaust, a turbo master, gauges(boost,Pyrometer&trans)and replace the crimpled up down tube. A turbomaster is awsome for 92-93 yr trucks. You will feel a big diff. Then 97 cooling mods. Keep the cooling system well maintained it's probably one of the weaker things w/the older trucks. Use the "search" function at the top of the page too.

Oh yeah! have you removed the snorkle in the inner fender yet. Refer to the advertiser section and look up Kennedy's web page. then go to tech tips, air box mods.

[ 11-23-2004, 11:30 AM: Message edited by: cruzer ]

[Spindrift]

Originally posted by ronniejoe:
For less money and effort, you can get performance out of the 6.5 that will rival anything offered today from any manufacturer in stock trim. How do you define "performance"? The total area under the curve needs to be evaluated. The 6.5 has no torque (relative to new, stock Dodge and Ford trucks) between 1000 and 2000 rpm.

[rjschoolcraft]

Originally posted by ronniejoe:
Here are two data plots. The first is my Suburban with the four different configurations that I descirbed above. The second is everything but the timing change vs. a Stock 1994 LB7 Duramax.

http://www.schoolcraftpowertrain.com/Pictures_&_Data/Comparison.jpg

http://www.schoolcraftpowertrain.com/Pictures_&_Data/Schoolcraft_vs_stock_Dmax.jpg

I guess I still believe real data when I see it and really enjoy pulling away from guys with shocked looks on their faces (driving Dodges and Fords) while towing heavy. :cool: Other than that, I'm just an idiot redneck... don't pay any attention to what I say. I really know nothing at all. :rolleyes:

[SANDMAN500LT]

Wow, thanks alot for all the feedback guys.....

As for buying a dodge to cure my want for a cummins, thats not gonna happen..Im my opinion, the cummins and the axles are the only things good about a dodge...Besides, my needs call for a real crew cab and I just flat like my truck...Just wish it had alot more poop!!

Maybe im not giving the 6.5 a fair shot..It is totaly bone stock...When I bought the truck the odometer read 208,000 miles....It ran great but not knowing its history I wasnt about to go modifying it just blow it up do to its high mileage.....Since then I have put 60,000 flawless miles on it and it still runs like a top and has great power....I have convinced myself that the motor must have beem overhauled at some point before I bought it and am alot less worried about doing some things to spark it up...

So i guess I want to know is if my 6.5 mod'd up is gonna pull my trailer up normal steep mountain grades here in the NW without going 25mph in first gear at redline...I know the trailer is heavy but its a average 40' fifth wheel toy hauler and thats what they weigh with the bikes onboard....Im fine with not going up hill so fast that you have to brake for corners but just dont wanna be that guy in the doggy chevy getting passed by loaded semis on the grade.

[Spindrift]

RJ,

I never said our trucks can't produce torque. And I really love to look at your print-outs by the way. When you have the opportunity, take a look at real torque curves of a new, stock Cummins and PS compared to our 6.5 TD.

And yes, I already knew you're the most intelligent guy on this forum.

[rjschoolcraft]

Well, it's good to see you finally got that straight. :rolleyes: I have "looked at" torque curves...for lots of engines for lots of different applications...most likely more than you have. It happens to be in my line of work for the past 20 years.

There's no argument that the 6.5 makes it's power and torque at higher rpm than the Cummins. Redline on the 6.5 is 3400 rpm. Most Cummins (in-line 6 Deere's, Caterpillar's, etc.) redline at about 2500 rpm. It's simply a different approach to engine design.

If you really want bottom end torque, we all missed out back in the early 80's. Allison developed the GT404 gas turbine engine for busses and semi trucks. The story I was told by the test engineer who was in charge of testing the engines goes like this... Two GMC tractor-trailer rigs loaded identically...one with the Detroit Diesel stock engine (can't remember which flavor) and one with the GT404. Both stopped at the bottom of a grade for a race to the top. The gas turbine powered truck flat left the diesel sitting. The driver topped the hill, pulled over, stopped, got out and had time to walk back to the crest of the hill to watch the diesel truck finish his run.

The point is both were "rated" similarly on power but the gas turbine had nearly instant torque on demand. This is similar to your argument about the Cummins, but much more exaggerated. BTW, that engine was later used to power generator sets for the Patriot missle systems. It's the only gas turbine engine ever put into production with a cast iron case.

You know... I don't attack you or Mark Rinker... yet you two seem to be fixated on attacking me. Your opinions are ok, but if I offer a differing opinion, well that's a problem. You should know that I don't just flippantly toss out the comments that I make. They're thought out and backed up with data or experience and are typically proven right in the long run. Now, before you smack me again ("I really love to look at your printouts"), you can look through past posts and see where I've made mistakes and promptly, humbly corrected my error.

I never claimed to be the "most intelligent guy on this forum". As I said, I'm just an idiot, redneck, dumb old farm boy. If that makes me the most intelligent, well...

What have I ever done to you? Is it because I tried to herd those lost souls over on that other forum in the right direction? I've given up on that. But I do find it interesting that the one guy went off and tried the famous "optic bump" and "dual breathers" and kept crying about "where's the power." He found it when he got a reflashed computer which was termed "a waste of money" by one "expert" over there. Interesting. But what do I know?

[Billman]

Now I understand how women get hooked on Daytime TV...

[Andy Chesek]

More Power,

Has Dave Hartman ever thought of ditching the IFS setup for a solid front axle? Seems like that would give him the clearance necessary for the NV5600 since he could remove the torsion bar crossmember...

[Spindrift]

Originally posted by ronniejoe:
You know... I don't attack you or Mark Rinker... yet you two seem to be fixated on attacking me. I can't speak for Mark, but as Billy suggests, it's probably that darn X chromosome that's actin' up again. :eek:

[cruzer]

Sandman, Boy I'm sure glad you ask these questions. To bad you didn.t find the answer you were looking for. "real" experiences w/a similar
load as you. There is alot more power in that engine. I don't know if there's enuff for you though. I will say you will probably be passing that doggy chevy. If you two have the same load.
The diff between stk and mod'd is significant.
When i did exhaust w/a little added boost it was noticeable. The bal of my mods was even better.

So actual dyno #'s are not real,intresting. Dodges'advertised #'s are real? Banks? The Tornado? Whoever? It all depends on what you are selling.

To me the issue is, With the right upgrades on the 6.5 it can equal a Dodge,PS or a Duramax in stk trim. Granted the mods really wake up the 6.5, and I'm very happy w/the power I have. And most important of all, it's paid for. But....If I owned one of the three mentioned it would only be stk for a short while.

[More Power]

For those of you who were not here in the late '90's, I'll restate the mission for the 6.5 Power Project.

The 6.5TD Power Project series began in late 1997, and was not completed till mid 1999. At the time this series began, Ford & Dodge set the standards for diesel towing power, and many 6.5 owners were looking for ways to improve the towing performance of their GM trucks. The question we hoped to answer with this project back in 1997-99 was whether a properly equipped 6.5TD could provide towing performance comparable to a "stock" 1999 model-year 7.3L Ford Powerstroke and/or Dodge ISB Cummins.

We made the case. But it goes well beyond the original mission to try to make the same comparison into perpetuity while the 6.5's development is virtually locked in time, circa 1999.

In our 1999 Pull-Off, the 1999 Dodge ISB equipped with an automatic transmission and 4.10 gears produced 40-mph on the hill with a 9700# trailer. The 1999 Ford PSD equipped with a 6-speed managed an even 50-mph. The 6.5 Project reached 48. Subsequent runs with a stock automatic equipped 1999 PSD produced 48.

People like to play the "what if" or "yah but" game, imagining scenarios where one truck or another would do better if equipped with X. I could play that game too.

I believe that if the Project 6.5 were equipped with a Peninsular non-wastegated turbocharger, we could run in second gear to the governor or 3800-rpm, which would produce 55-57-mph. The factory GM-8 turbo is too restrictive to run in 2nd gear against the governor without blowing the EGT's, so this truck was run in 3rd gear (direct). Not a single stock Ford, Dodge or Duramax run since has been able to gain speed when run in direct on that hill with a ~10K trailer. In fact all "stock" PSD, Cummins, and Duramax powered trucks we've run to date lose speed while running in direct on the hill with a 10K trailer. The 6.5 Project did not lose speed in direct, even with its GM-8.

If a 16K trailer must be part of the equation, I'd look for another truck. Aside from asking too much from the '90's GM powertrain, the truck is simply not rated to safely pull that amount of weight. In my opinion....

MP

[SANDMAN500LT]

Thanks Cruzer, thats how it goes I guess....I have pulled a 33' fifth wheel for 2 years now that weighs in around 11,000k loaded...The truck has done real well (for what it is) with that...Runs down the highway and through the smaller rolling hills in O/D maintaining 70+mph....When I hit the the steeper hills it slowly falls off until I am in 2nd gear going 35-40mph with my foot on the floor.....That isnt the greatest, but if the mod'd 6.5 could at least maintain a hard 2nd gear pull at 40+mph with the new heavier (16k) trailer I would probably be satisfied...

[SANDMAN500LT]

MorePower, Im very aware that I am trying do more than the truck was origonally "RATED" for..However, I am confident in both my ability and the trucks ability to safely pull this trailer with the exception of the lacking power....After all, the trailer is a 1997 40' Kit Patio Hauler...What truck in 1997 was rated to safely pull this trailer?.....The bottom line is, there is thousands of RVs on the road that are heavier than mine and being pulled by the same trucks equipped with 454s....I feel the trucks running gear is eqivilant too or better than alot of whats currently offered and only lacks POWER to keep up with the big dogs.....

To be completely honest...I bought this truck a few years ago knowing it had high mileage and was fully prepared to yank the tired 6.5 out and replace it with a healthy big block.....Well since then the 6.5 has done nothing but impress me with great mileage,reliability, and much better power than I thought they had....Needless to say, I'VE BEEN CONVERTED!!

Im trying to gather as much info as possible, as to hopefully not make a poor decission.....One of 2 things WILL happen...The 6.5 will get modified or it will get a cummins....The 6.5s are not cheap to build and it would suck to spend several thousand dollors on something that isnt going to do what I need it too......On the other hand it would also suck to spend thousands on a coversion thats gonna vibrate,break parts, and be noisy and unpleasant to drive....

Thanks again guys for all your info.....Please keep'em coming..

Tony

[sidedump]

Powertrain Control Solutions had a video as to why it is not a good idea to exceed your GVW.
http://www.powertraincontrolsolutions.com/modules.php?name=Content&pa=showpage&pid=25

[markelectric]

I had a 94 Crew cab 4x4 that I did a bunch of mods to and never was impressed with its towing ability. When I got the triaxle enclosed trailer, I knew something had to change. I found a 99 dodge 6sp dually. It came with an Edge ez. I thought I had it made. Took it to a retired Cummins guy for a tune up before a series of long trips. He pulled the Edge, swapped the injectors and dumped his own program into the computer. If I thought it was nice before this, then I have now died and gone to diesel heaven. have never pulled anything as easy as the Cummins does. How about a 30 ft enclosed trailer,11ft tall running down the interstate at 70 mph with the cruise doing the work.
I must say as easy as the dodge is to drive, it is THE most uncomfortable truck I have ever sat in. Even with their premium seat I have serious back pain after a couple hundred miles.

[Diesel Dan]

Originally posted by SANDMAN500LT:
On the other hand it would also suck to spend thousands on a coversion thats gonna vibrate,break parts, and be noisy and unpleasant to drive....
Tony I'm not really impressed with the noise level in my '00 6.5TD. When cold the 6.5 is louder than my 12V cummins. Also cruising empty the 6.5 is more annoying than the CTD, the dodge does have a louder drone due to its 4" exhaust.

As far as the motor on the 6.5, it was loud with 95K miles, original injectors and new IP. Still loud with new motor, injectors and IP. It is most definitly louder than my 1st gen CTD I had.

The best thing about the GM trucks is the interior and a real crewcab. As of yet dodge doesn't offer enough cab room for my taste. Maybe in the future I'll pull the drivetrain from the dodge and install it in the chevy. I'd even use the dodge auto. Some trans places like ATS, Suncoast etc guarantee them for over 1000 ft/lbs of TQ.

[DogDiesel]

While I have no regets about my conversion to a 5.9L: I confess I converted out of pure anger.

My 6.5 has only 44K on it. My perfectly matched turbo had less than 10K on it. My 300HP 6.5 package was perfect. Damn sweet. Pulled magnificantly. Ran awesome. FAST!

But all that wonderful precise perfectly machined, balanced, ceramic coated, expertly matched package was trashed in a nano-second by a harmonic balancer. Worse, it stranded my wife. That has happened only once. The harmonic balancer was new, with only 44K. I was in Iraq with a few more issues to be worried about and I get word this happened.

Well, pure anger set in. I flew into action to eleminate the problem. Like I say NO REGRETS.

I have and always will be complimentary about the performance of the 300 HP package I had in my truck. But mere mention of the crappy harmonic balancer design sends me to anger orbit.

I am a senior guy in the Army's Maintenance Training and support. We are visciously working on an engine package that can be changed in 30 minutes. Likely not a 6.5
Wayne