MaxPF can't decide for himself, so he needs help!

[MaxPF]

Ok guys, here's the deal. I have been going back and forth, back and forth, back and forth on whether I should swap the Cummins I have (P-pumped 12V 5.9) into my K5, or keep the 6.2, put a turbo on it, and be happy until I can maaaaybe afford a P400 sometime down the road.

I am actually most of the way there for a Cummins swap - Brian (BadAss90K5) is gracious enough to loan me his brand new $900 South Bend clutch and flywheel, not to mention other stuff, to make it happen if I should so choose. Yes, Brian is a true friend and a generous human being all around However, there is still quite a bit that needs to be fabbed and purchased. It is doable, but the question is: should I do it?

Pro's and Cons of a Cummins swap:

Pros:
* Super strong and proven engine
* Stupid power if I so choose
* Fuel economy probably a tad better than the 6.2/6.5 due to it's direct injection architecture
* Injector pump is bulletproof
* Large torque rise makes better use of available gearing
* I have it, and it is basically ready to go
* Everyone thinks a Cummins is cool, A Cummins in a K5 would be even more cool

Cons:
* Heavy SOB - might force a future axle upgrade, and I definitely need to strengthen the frame (I was planning on doing it anyway, even if I keep the 6.2)
* At least a weeks worth of fabbing needed just to make it fit
* Noiser and more vibration than the 6.2
* 6 cylinders sound like ass (just my opinion)
* Possibly increased tire wear due to extra weight (equivalent to two fat bastards sitting on the hood, or the weight of a burly winch bumper and winch)
* Engine has more miles than the 6.2 (150-200k vs 60k) and definitely more than a new P400 would have
* Custom stuff means more difficulty sourcing repair parts if needed
* Needs a $900 (or more) clutch because it makes so damn much torque

Pro's and Cons of keeping the 6.2, turboing it, and possibly getting a P400 in the future:

Pro's:
* Light weight - less stress on front end when I'm wheeling (ho hardcore rockcrawling though - I'm done with that).
* It's already there - nothing to do but add the turbo (which I have - just needs a rebuild)
* it only has 60k miles on it (give or take). Should last quite a while longer.
* Since it's an OEM configuration, sourcing parts in Podunk, Bumfockistan is much easier
* Quieter and more civilized than a Cummins (YMMV on that)
* Cheap to fix - IP is dirt cheap compared to a P7100
* Easier on front suspension and tires thanks to less weight
* V8's just sound sooo much better than 6's do
* When a clutch needs replacement in the future it won't cost as much... unless I put in a hopped up P400, in which case a good (read $$$) clutch will be needed to handle the power, just like the Cummins...

Cons:
* 6.2 not as durable as a Cummins - P400 is probably bulletproof up to 350-400HP, but there is no long term evidence yet.
* 6.2 will never make the power of a Cummins - the P400 will make all the power I want (300HP or so), but it comes at a price ($$$)
* Fuel efficiency probably not quite as high as the slightly more efficient Cummins
* Less torque rise means I may be forced to downshift on hills that a Cummins will hold in top gear, even though they may be able to hold the same speed
* IP lasts about 100-150k between rebuilds (fortunately, they're cheap to rebuild)
* Higher HP configurations in non-marine enviroments are a challenge to keep cool when you are working them
* It isn't as cool as a Cummins, and everyone thinks it will blow up as soon as you step on the throttle
* I would eventually want to replace it with a hopped up P400. That engine, plus DB4 IP, injectors, etc. will end up costing 10grand plus for everything. There is no telling how long it might be before I could afford it, if ever
* AMG doesn't sell spare parts for the P400 - if something breaks, your tubed (unless a common 6.5 part will work).
* Travis (mtnman) won't get the 6.2 if I keep it in the truck


That's about all I can think of at the moment. Here's what I want from my rig:

* Daily driver
* Hunting/fishing/camping/moderate wheeling (no hardcore stuff though)
* Needs to be reliable to the end of the world and beyond
* Needs to be comfortable on long trips

So there you have it. My concern, and the reason I have been so indecisive, is that the Cummins swap is an unknown. I have never driven a Cummins K5, and few people have even ever done such a swap. Until it is done and you drive it, how do you know if you made the right choice? The Dodges with Cummins that I have driven all ran good and drove nice enough, but those are 8000lb trucks. How will it work in a 6000lb Blazer. If I think it sucks, I have a lot of $$$ and time to convert it back

Those who know me personally know I can do the swap right - I mean really right. Still, will it be a vehicle I can live with afterwards? Well, the only real way to know is to do it. The other option is to take the known road and stick with what I have. Thus, the purpose of this poll.

So, that's my spiel. Time to vote, and tell me what you think.

PS: Don't even mention the 4BT. They really sound like ass, they shake too much, and they won't make the gumption I will eventually want.

 

[bavarian_blazer]

max,

get a p400, don't even hesitate! (and tell me where you got it ;-) ) , do a fine write-up of all the things you do with the engine and where you got the parts (that would save me tons of work

Greetings

Flo

 

[sixb]

I am a Cummins fan especially the 12v I have owned an 02 and now a 91 and my old man has been using them on his Ranch since 95 they just don't quit.
I also disagree that they are noisier and rattle more than a 6.2 my 86 m1008 will make you want to kill yourself on a long drive compared to my 91 Dodge both are 3spd autos but there is quite a gearing difference though 4.56 compared to 3.07
It is a very expensive swap though, I plan running mine till I die then my kids and Grand kids will do the sameusing it as an expedition(hunting & fishing) rig only in the rocky mountain west

 

[Mikey von]

I would say go with a fully custom 6.2L. Something along the lines of a bad-ass main cap girdle, roller rocker heads, and tons of other goodies but where would the originality be in that?

I now almost feel bad with the engine sitting in my garage awaiting to go into my suburban.

I say stick with your 6.2L for now. When unsure, it is usually better to err on the conservative side. The cummins swap does sound bad-ass though and it sounds like you are almost there already.

 

[ZukiJohn]

12 valve

I'll trade you a 454 th400 203 for the cummins stuff....

 

[tRustyK5]

One other factor of the engine's weight is it's affect on the rest of the chassis. A K5 with a 6.2 is only slightly nose heavy, more weight up front means the rear wheels will unload a lot faster under heavy braking and handling in general will be noticeably worse.

A hot 6.2/6.5 should be tons of fun for your planned use, and sound better. I also don't like the 6 cylinder exhaust note...

I'd personally love to see twins on a P400, with dual 3" exhaust and no mufflers.

Rene

 

[ZukiJohn]

Ok a dumb ? whats a P400??

 

[fallout232]

I say option "Z" scrap all the above ideas and go with a 4bt. Sell trade the 6bt for a 4bt. All the accessories and bellhousing's etc. interchange between the 4 cylinder and 6. The 4bts can be made to put out 225-275 reliable horsepower and weigh a couple hundred pounds less. Plus they get 20-30 mpg.

I have seen several 80's model 6bt swaps which ultimately resulted in broken frames. 2 broke right under the firewall. That is alot of weight for these "flexy" frames

 

[RockinChevy]

I'll trade you a 454 th400 203 for the cummins stuff....

Dude, I'll buy your 400/203 stuff this weekend!

 

[mtnman]

i say option "z" scrap all the above ideas and go with a 4bt. Sell trade the 6bt for a 4bt. All the accessories and bellhousing's etc. Interchange between the 4 cylinder and 6. The 4bts can be made to put out 225-275 reliable horsepower and weigh a couple hundred pounds less. Plus they get 20-30 mpg.

I have seen several 80's model 6bt swaps which ultimately resulted in broken frames. 2 broke right under the firewall. That is alot of weight for these "flexy" frames

ding,ding,ding we have a winner!! :d :d :d

 

[RockinChevy]

I'm getting quite comfy with the 6mpg from the 454.

 

[KirsL]

A P400 is what the redesigned 6.5 turbo diesel is called.

While the weight issues are a factor to consider with the cummins, if a long life over 400 hp is your goal I would run a cummins. My chevy was originally a stock 6.2 diesel, wasn't fast but did ok. When the engine died 6 years ago I was deciding the same thing you are; Which engine to run. I went with a heavily modded 6.5 pushing pretty damn close to 300 hp at the flywheel. The truck is crazy fast for a lifted truck. The motor makes great power from idle to the governor, which is 4200 . Course 18 lbs of boost helps too. And no I do not have an intercooler, yet . Being a low compression engine, 18:1, helps it live with that kind of boost. Plus with semi careful driving can get 15 mph in mix driving. Sounds pretty good so far.

That's some of the good. The bad and there aren't many, but they are substantial enough for me to consider pulling this engine and either building something not as wild or a cummins swap.

The biggest issue is very cold engine temp starts. Meaning the trucks been sitting for 8 hours or more turned off and unplugged. Because of the lower compression and the heavy fueling DB2 you have to hold the throttle about a 1/4 open, otherwise the engine WILL NOT start, period. BUT holding the throttle open causes the engine to dump raw fuel out the exhaust smoking out the neighborhood. Bad for engine and bad for neighborhood relations. Once the engine has some decent heat in it, it cranks up instantly. I'm currently working on putting a cummins intake heater to work with the glowplugs and see if that helps any. This isn't an issue that just I fight. If you check www.TheDieselPage.com other people with 18:1 engines suffer the same problem.

The other problem is drivability, which in my case I think might be a issue with fuel delivery , but just cruising is kinda hard for this engine to do. It really likes to do 2 things, idle or hammer down . Which can make driving in traffic interesting to say the least. Passing isn't a problem at any speed though .

Now having said all that I'll add that I didn't vote and here's why. I say turbo your current 6.2, you have the parts. Drive the truck like that for a bit and see how you like it, plus you can save up some money for later. Now by later I mean like a couple months or thousand miles. For the purposes you list I think a turboed 6.2 will fit your needs nicely. Plus then you could sell your cummins to me .

Sorry its long, if you have any questions about my setup shoot me and I'll be happy to help.

 

[MaxPF]

ding,ding,ding we have a winner!! :d :d :d

You guys missed the part where I said "No 4bt's!!!".

 

[MaxPF]

I talked to someone whose judgment I value. He came up with a logical suggestion: Put the Cummins in, and if I don't like it, pull it, sell it, and then put in a P400 (or whatever). After all, I already have 90% of what I need to do the swap, and since I'm not going to alter the frame (Just add massive bolt-in crossmembers and reinforcements) where the motor mounts attach the swap would be reversible. It sounds reasonable to me...

BTW, I have this same poll going on elsewhere - the Cummins is winning everywhere but here. Lotsa 6.2 diehards on this site

 

[DEMON44]

One other factor of the engine's weight is it's affect on the rest of the chassis. A K5 with a 6.2 is only slightly nose heavy, more weight up front means the rear wheels will unload a lot faster under heavy braking and handling in general will be noticeably worse.

A hot 6.2/6.5 should be tons of fun for your planned use, and sound better. I also don't like the 6 cylinder exhaust note...

I'd personally love to see twins on a P400, with dual 3" exhaust and no mufflers.

Rene

see I'm totally opposite. i CANNOT stand the sound of V8 diesels. I-6 sounds like a diesel engine should sound. it like music to my ears.

 

[MaxPF]

A P400 is what the redesigned 6.5 turbo diesel is called.

While the weight issues are a factor to consider with the cummins, if a long life over 400 hp is your goal I would run a cummins. My chevy was originally a stock 6.2 diesel, wasn't fast but did ok. When the engine died 6 years ago I was deciding the same thing you are; Which engine to run. I went with a heavily modded 6.5 pushing pretty damn close to 300 hp at the flywheel. The truck is crazy fast for a lifted truck. The motor makes great power from idle to the governor, which is 4200 . Course 18 lbs of boost helps too. And no I do not have an intercooler, yet . Being a low compression engine, 18:1, helps it live with that kind of boost. Plus with semi careful driving can get 15 mph in mix driving. Sounds pretty good so far.

That's some of the good. The bad and there aren't many, but they are substantial enough for me to consider pulling this engine and either building something not as wild or a cummins swap.

The biggest issue is very cold engine temp starts. Meaning the trucks been sitting for 8 hours or more turned off and unplugged. Because of the lower compression and the heavy fueling DB2 you have to hold the throttle about a 1/4 open, otherwise the engine WILL NOT start, period. BUT holding the throttle open causes the engine to dump raw fuel out the exhaust smoking out the neighborhood. Bad for engine and bad for neighborhood relations. Once the engine has some decent heat in it, it cranks up instantly. I'm currently working on putting a cummins intake heater to work with the glowplugs and see if that helps any. This isn't an issue that just I fight. If you check www.TheDieselPage.com other people with 18:1 engines suffer the same problem.

The other problem is drivability, which in my case I think might be a issue with fuel delivery , but just cruising is kinda hard for this engine to do. It really likes to do 2 things, idle or hammer down . Which can make driving in traffic interesting to say the least. Passing isn't a problem at any speed though .

Now here is another con for the P400. In order to get the power I would expect from such a costly swap (which would probably never happen) I would need a low compression version. Then the engine becomes "tweaky", which I don't want. I could run the 20.3:1 version and have easier cold starting, but then I am limited to 250HP I'm not gonna spend a pile of coin for a measly 250 ponies

 

[MaxPF]

see I'm totally opposite. i CANNOT stand the sound of V8 diesels. I-6 sounds like a diesel engine should sound. it like music to my ears.

You're just like Travis (mtnman). He says my 6.2 "doesn't rattle right" Oh well, I figured it I really don't like it I can put enough muffler on it to make it nearly silent. The rattle from the engine itself doesn't bother me so much, it is more the exhaust note. Especially from straight piped Cummins

 

[mtnman]

see I'm totally opposite. i CANNOT stand the sound of V8 diesels. I-6 sounds like a diesel engine should sound. it like music to my ears.

I AGREE!!
And yes, Greg, I did miss the part about no 4BTs

 

[bavarian_blazer]

@Max:

do you already have a source where you can get a p400 from?

 

[Wrench]

I'll add a Cummins vote, I'm just beginning mine after long deliberation over the exact same question. I have an AMG 506 block, I have a Banks turbo kit that would fit my truck easily and be far more efficient than the GM-x turbos, I have a full stud kit, top and bottom, for the 6.5, I have a fresh 4911 pump. Stuff I've collected while planning the indestructible 6.5. I just don't like the ceiling--ok, I can buy a very expensive DB4 and make 400 horse with the right turbo. But I can spend the same money and get a Industrial Injection 14MM P-pump that will support 8-900 horse with the right turbo(s) and tuning.

I bought a '91 5.9/NV4500/NP205 driving donor truck with 130K miles for $2700 and sold the rolling chassis for $1500, plus some other small parts that brought my cost down to about $1K. I then bought a '96 5.9 auto 4x4 dually for $1500, also running and driving with 150K miles, and an HE351W turbo for $250. Custom engine mounts and crossmember from CrewCab59 (Scott) were $539 shipped to my door. Remember this is all Canadian dollars.

So--I have $3500 into it for two complete engines, one P pumped and one VE, a Dodge NV4500 and a Dodge 47RE, a Dodge 29-spline 205 and a Dodge 241DHD?, three different turbos including the ones on the engines, two complete engine and chassis wiring harnesses, and application designed mounts and crossmembers, and I still have a spare set of axles (D60 and D80) to sell, use, or whatever.

I can also sell the complete original drivetrain from my crew cab (already sold the NV4500/NP205 combo for $2100, and still have the turbo'd 6.5 with a serpentine kit on it) and I don't have to use any adapters in the driveline, which I prefer for the sake of strength, reliability, and parts availability. I can save my 6.5 stuff for a future project that won't see the same towing duty (nice DD suburban?) or sell it.

That leaves with a fair bit of room to do some injectors, pump mods, fresh gaskets, maybe even head studs, for a lot less than most people plan on spending on a 5.9 swap.

Long post to say that if you keep your eyes open, you can do the swap "right" for the same money as building a 6.5, and you never have to think about it again. My rig is for serious towing duty, and after it's set up I want to do oil changes and grease, nothing else.