What do I need to do on a rebuild to get a 6.5L to live at full throttle towing?

[john65td]

I was just in this place about a month ago. i priced it out and did research. to rebuild a 6.5 and build it. head studs, crank, main stud girdle, heads, att and all that it was around 4500 to rebuild the 6.5. i found a cheap cummins for 1000. im buying a new 5 speed and selling my 6.5 parts its costing me the same as it would be to keep my 6.5. thats with buying new injectors and turbo for the cummins. i found it was the same to rebuild or swap. and with the swap there is more power potential. find a mechincal 12valve p pump cummins no eletronics to go bad

 

[Woody35]

I was just in this place about a month ago. i priced it out and did research. to rebuild a 6.5 and build it. head studs, crank, main stud girdle, heads, att and all that it was around 4500 to rebuild the 6.5. i found a cheap cummins for 1000. im buying a new 5 speed and selling my 6.5 parts its costing me the same as it would be to keep my 6.5. thats with buying new injectors and turbo for the cummins. i found it was the same to rebuild or swap. and with the swap there is more power potential. find a mechincal 12valve p pump cummins no eletronics to go bad

but then you have to deal with suspension and transmission issues. which cost a lot more.

 

[Dave01]

$4,500 rebuild is a pretty serious rebuild! I would think if the purpose is to stay together towing 8,000 lbs. it could be done for less, but then again I'm no expert on rebuilds. I do realize that if you go with the ATT, need an IP as well, it will add up quick.

In the end I think it depends on how much you like your truck. If you like it, do the rebuild. If not, look for something else. You'll probably have close to the same money in either way.

 

[bk95td]

The gear ratio that the truck has was not mentioned. Perhaps lower gearing would help from having to floor it.

 

[WarWagon]

The gear ratio that the truck has was not mentioned. Perhaps lower gearing would help from having to floor it.

4.10's...

Yes, it is an intresting drive vs going to other flat areas of the state.

 

[buddy]

Did you already turn up the fuel output on the DB2?

My C1500 could pull that load without the pane on! You dont need a Cummins for this, the 6.5 has a lot of untapped power, it just has to be set up right. With a rebuild it can be done right. Or just order it from diesel depot if you dont want any hassle. $3400 for a 6.2/6.5 hybrid with the goodies. Add a Scat crank, fluidampr, and maybe a few more coated areas and youre set for $4k plus shipping.

FTB is an important modification, along with the OPS relay mod in these OBD1s.

 

[WarWagon]

This is a 4x4 so it may be on the fat side. DB2 has a 1/3 turn and turbo boost max at 14 low RPM full load. (Odd the boost falls off at higher RPM.) No smoke.

Didn't think FTB would matter at this power level. I will look into that closer. Maybe that is why high RPM boost falls off?

 

[NVW]

You may have been starving for fuel as you point out with the boost falling off.

 

[Matt Bachand]

Sorry, I'mfftopic:

Actually, it's a nice run if you appreciate geology and observing the changes in vegetation and the variety of colors in the landscape. Scrub cactus give way to the Giant Saguaros; the valleys starting in Surprise have water, and therefore, Cottonwoods 70' or better with tall grasses carpeting the hillsides. Unobstructed views abound and rolling down into Phx at night is awesome. The road was mostly 4 lane the whole way (may be all the way now). Changes in weather only enhance the beauty but then there's the summer heat in the "Valley of the Sun" (and they aren't kidding) and that feels like hell and can joy of any drive. Opposition in all things I guess...like choices in trucks and or power packages, towing options, mods etc.
Back to the topic at hand.

I have to agree with the other posters.
Aside from the ensuring the A/C condenser and radiator are kept clean, cooling upgrades (with the right water pump), balanced cooling set up for the heads and the ATT, all I can say is perhaps backing off 5 mph or so would help. Often "Less is More" and / or "Slow is smooth and smooth is fast." Meaning less down time for repairs. You'd only be adding about 30 minutes to each leg.

I would enjoy it in Buddy's truck, or TD's, or even mine with the KOJO and ATT. I would enjoy it in my Corvette if I had one. I would just hate it with my truck as is!!! I'd be staring at the guages the entire time hating life!!!!

Sounds like a true test of any truck. You are pushing the limits of almost any LD truck.

I do like how Buddy gives us faith that he could pull that run no problems. I'd bet a few other of our 6.5's would do that well also.

I also have faith that my truck as it stands would be one LONG ASS ride.

 

[buddy]

Having the ATT and WMI is a big bonus on hills like that.

If the boost drops while accelerating and not pulling up on the pedal, then likely you just need a stiffer spring on the wastegate. Although, with no pyrometer you were already tempting fate.

 

[john65td]

this was my 6.5 build i was gonna do. head studs from kennedy $225, scat crank from heath $459, kennedy main stud girdle $185, new heads $670, cooling upgrade $300, fluid dampner $400, rebuild kit ( Piston Ring Set, Main Bearing set, Rod Bearing set, Hi-Volume Oil Pump w/pick-up tube and screenDouble Roller Timing Chain set, Complete engine gasket set, Rear Main Seal, Head Bolt sets ect) $1000, rocker buttons $20, vin f intake mainifold new exhaust mainfold $250, new pistons $300, att $800, lifters $120. then the cost of machining block and it adds up quick. withe the items i listed the total is $4729 that dont include shipping and other unforseen expenses. thats more than what my cummins swap is. plus if you swap you can sell the old drive train and make out. for tranny it aint too bad im gettin a reman gm nv4500 for $1175 then putting a dodge input shaft in $134 then it bolts to the cummins and my t-case and i might be able to reuse my drive shaft. but whatever you do is your choice, and what you think is your point of view, every body has the own ideas and game plans. im just saying what i did and the route i went its just information and my thoughts.

 

[WarWagon]

You may have been starving for fuel as you point out with the boost falling off.

Buddy and you are on to something here. I have a TM on it. New Lift pump. The boost was holding higher in higher RPMs after the lift pump change come to think of it. The passenger side ex manifold was leaking very badly though maybe loosing drive pressure. Had a tick to it last week. Assumed it was an exhaust tick but could have been the #1 injector.

Wonder if the IP is weak? The engine falls over above 2500 RPM and losses power at higher RPMs. On a light hill in 3rd around 60 MPH the TCC feels like it kicks in, RPM drops, in 3rd gear and it will start to accelerate - otherwise the speed would be steady on the hill WOT. Only does this after a bit or if I lift the throttle some.

I always thought it was the GM3 choking up the exhaust. It did this with the factory spring can too.

No I do not have the time to swap a Cummins in - Need the truck next week. Is there a ready made kit to make this a "bolt on" type swap? Looks like there is demand for it. Because it goes like this: Blew engine, need the damn truck back up and running NOW! Aka need: Crate engine, running take out, patch whatever on blown engine, or drop in Cummins kit with EVERYTHING and you source the 12 valve or include one. There is little market for people who have time to do it / make it themselves over months because they will do just that.

 

[turbovanman]

Good thread, :thumbsup:

$4,500 rebuild is a pretty serious rebuild! I would think if the purpose is to stay together towing 8,000 lbs. it could be done for less, but then again I'm no expert on rebuilds. I do realize that if you go with the ATT, need an IP as well, it will add up quick.

In the end I think it depends on how much you like your truck. If you like it, do the rebuild. If not, look for something else. You'll probably have close to the same money in either way.

Things cost money, do it right or don't bother, ):h

 

[WarWagon]

Good thread, :thumbsup:

Things cost money, do it right or don't bother, ):h

This is a 6.5 Forum thread. :nono: If I had the money I would be in the Duramax forum! ):h

At this point I plan on having to pull the engine again in the future. However it needs to get there on budget and time is also not my friend here. Truck down = no work…

To do it right would be a Bill Heath built 6.2 with oil line and head gaskets for the 6.5 turbo. Ceramic pistons, Main Studs, Head studs, and a balanced rotating assembly. I would even have the heads ceramic coated. Without the heads coated it comes to $3500.00 plus shipping. 2 year 24K warranty. 2 week lead time... I paid $4000.00 for the truck! With a built engine resale value is still same as with old running engine.

So to get it through tomorrow when I can afford to put in a real engine… I can buy 2 military surplus 6.2L engines and put head studs in etc for the cost of a built engine… (Only need 1 engine.) And they have a 90 day warranty.

Cooling system working and EGT gauges I should be above the level I was before the meltdown.

The only way to know on the ATT is to get one myself as I hear both ways on it.

 

[buddy]

When you say a Heath engine, do you mean the improved Diesel Depot engines?

One of those would be very nice. The ATT does help tremendously when under load. I put my GM4 back on to compare and its feels like the engine is working much harder at higher RPMs and when going over 100mph. And thats because it is and the exhaust is not flowing as smooth and not fully escaping the cylinder.

635 said it felt like he lost 100hp, when referring to going back to standard injectors, but he also went back to the GM8 because a bad propane experience took out all the injectors and ATT. He could no longer tackle the steep hills with the same ease and lost 20mph on his speed up them.

 

[packers905]

That was a good one [if I had money I would be in the duramax forum] very funny but true in my instance as well!!!! Good luck with the military engine I have always been curious about them

 

[Brooklyn Tow]

Build what you could afford and keep it moving!

 

[midniteplowboyy]

Yea, the DB2 seem to start falling off in the upper rpms, I think the turbo hinders some also. Crank the govenor screw all the way in, this will make it pull harder up top, just watch the revs.

Where is your TPS set at? Adjust it lower, like 0.45v @idle and put a resistor across the trans force control solenoid wires to raise pressure back up for the TPS drop and for the cranked DB2, this will help hold OD and lockup longer.

Put a manual TC lockup switch on it and by all means get a pyrometer, who knows what temps she was running with a cranked DB2.

Give me a few weeks, my 92 is getting a makeover(think its time 350k), new 4911 IP(max fuel stroke, max govenor and 1/4 turn on the TP screw), new stock Bosch injectors, original GM2 turbo and straight piped stock exhaust(by the way was 3" in 92, not 2-3/4" like 93up). I'll see how it runs compared to my 93 with just the fuel stroke maxed, Bosch marine injectors, WH1C Holset, 4" exhaust, 0.010 headgaskets and IC.

 

[buddy]

With new injectors, Id have them pop tested and balanced correctly by someone you trust, as out of the box they can be way off.

 

[WarWagon]

Yea, the DB2 seem to start falling off in the upper rpms, I think the turbo hinders some also. Crank the govenor screw all the way in, this will make it pull harder up top, just watch the revs.

Where is your TPS set at? Adjust it lower, like 0.45v @idle and put a resistor across the trans force control solenoid wires to raise pressure back up for the TPS drop and for the cranked DB2, this will help hold OD and lockup longer.

Put a manual TC lockup switch on it and by all means get a pyrometer, who knows what temps she was running with a cranked DB2.

Give me a few weeks, my 92 is getting a makeover(think its time 350k), new 4911 IP(max fuel stroke, max govenor and 1/4 turn on the TP screw), new stock Bosch injectors, original GM2 turbo and straight piped stock exhaust(by the way was 3" in 92, not 2-3/4" like 93up). I'll see how it runs compared to my 93 with just the fuel stroke maxed, Bosch marine injectors, WH1C Holset, 4" exhaust, 0.010 headgaskets and IC.

The emissions test here is a smoke test. Floor it in neutral and hold it on the governor till we get a reading... :mad2: I will check the trans stuff out.