Healthy Horsepower Numbers?

[Roadrunner6.7]

Good evening, my fellow 6.7L Cummins owners.

So this question comes from seeing different transmission HP ratings.

I understand that these 6.7 are reliable engines, but seeing how you have transmissions rated for 500 up to 1000+ horsepower, what’s the limit for these things to still be reliable but beefed up?

Is it 500 or 750 hp?

I understand there are plenty of variables that factor in.

So, what power level will still allow for that longevity and reliability?


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[IndyRamMega]

It depends on how you build it, bud.

I mean, if you're talking stock motor zero upgrades to it.

You'll blow a head gasket if you put on a bigger turbo and tune it with no studs, but if you build it properly and drive reasonably around 700 ponies.

With a single charger at those power levels, I think how you drive it increases longevity.

My question for you is, what are you doing with your truck?

Just a DD, a Tow rig?

What is your HP goal, and for what reason?

Do you want to be fast on the street?

Sled pulling?

It's a rabbit hole only you and your wallet can decide on.

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[OneTon]

Up to 700ish HP, you'd want head studs and supporting transmission (auto) or clutch (manual) mods.

Potentially some valvetrain updates, too, if you're revving it out a bit more.

Anything over that, and you would need to venture into stronger connecting rods.

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[6.7 Coal Train]

It depends on how you build it, bud.

I mean, if you're talking stock motor zero upgrades to it.

You'll blow a head gasket if you put on a bigger turbo and tune it with no studs, but if you build it properly and drive reasonably around 700 ponies.

With a single charger at those power levels, I think how you drive it increases longevity.

My question for you is, what are you doing with your truck?

Just a DD, a Tow rig?

What is your HP goal, and for what reason?

Do you want to be fast on the street?

Sled pulling?

It's a rabbit hole only you and your wallet can decide on.

A bigger non-VGT turbo will bring drive pressure down.

You'd be likelier to blow a healthy head gasket, turning the stock VGT up to max and hammering it WOT everywhere.

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[IndyRamMega]

A bigger non-VGT turbo will bring drive pressure down.

You'd be likelier to blow a healthy head gasket, turning the stock VGT up to max and hammering it WOT everywhere.

Absolutely.

I should've spelled that out more when i typed it.

A single non-VGT charger.

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[Corkey]

Compounds with the heavy torque load down low are what shrink rods or bend\shoot out the block on stock rods.

Guys have spit out +750hp with no issues, but I also am weary of anything over that; guys have gotten 700, 800, and 900hp out of a stock bottom end.

We hear it all the time; it depends on the user.

Boosted launches 2W 4W, hitting limiter every gear, grocery-getter, sled pulling, towing heavy, etc.

With the single, the higher your hp, the less drivability you get.

The compounds set up, which most can't afford, IMO, you get both of the best worlds.

Power down low and up top, creating much more achievable power, but still have great drivability.

Of course, to a point, you have two monster turbos, which need six garden hose injectors to spool both.

You run out of a daily driver, and smoke is avoidable.

For example, which is the route I'd take, 2nd gen swap, S467.7, FASS or air dog 165GPH minimum,#103 springs and push rods, 10M CP3 Minimum, %100 over "200hp" Injectors, ARP 625 studs, doc visit, and depending on tire size, do gears to prolong the trans.

You have a reliable +750hp set up for the motor all day.

Trans- Deep-dish pan, Thermostatic by-pass kit, zero flex RevMax VB, RevMax clutch drum, Billet 300M input shaft, RevMax triple converter, increase line Pressure " docs magic, Improve shift points " doc ."

It's a spendy road, but I would start on the trans before any power upgrades if I could do it over again.

The 68s are nice but have several issues once power is thrown at them.

Anything you can do to keep the heat down will be the key.

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[Roadrunner6.7]

It depends on how you build it, bud.

I mean, if you're talking stock motor zero upgrades to it.

You'll blow a head gasket if you put on a bigger turbo and tune it with no studs, but if you build it properly and drive reasonably around 700 ponies.

With a single charger at those power levels, I think how you drive it increases longevity.

My question for you is, what are you doing with your truck?

Just a DD, a Tow rig?

What is your HP goal, and for what reason?

Do you want to be fast on the street?

Sled pulling?

It's a rabbit hole only you and your wallet can decide on.

If I were to go that route, it would be street driving.

I know some guys like to build these for racing.

I had a hellcat prior, so Im trying to learn as much as possible about what the 6.7L is capable of.


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[Roadrunner6.7]

compounds with the heavy torque load down low are what shrink rods or bend\shoot out the block on stock rods.

Guys have spit out +750hp with no issues, but I also am weary anything over that, but guys have gotten 700,800,900hp out of a stock bottom end.

We hear it all the time, it depends on the user.

Boosted launches 2W 4W, hitting limiter every gear, grocery getter, sled pulling, towing heavy, ect.

With the single, the higher hp you go, the less drivability you get.

The compounds set up, which most can't afford, IMO, you get both of best worlds.

Power down low and up top, creating a lot more achievable power, but still have great drivability.

Of course, to a point, you have two monster turbos which need 6 garden hose injectors to spool both, you run out of a daily driver and smoke is avoidable.

For example, which is the route I'd take, 2nd gen swap, S467.7, FASS or air dog 165GPH minimum, #103 springs and push rods, 10M CP3 Minimum, %100 over "200hp" Injectors, ARP 625 studs, doc visit, and depending on tire size, do gears to prolong the trans.

All day long, you have a reliable +750hp set up for the motor.

Trans- Deep-dish pan, Thermostatic by-pass kit, zero flex RevMax VB, RevMax clutch drum, Billet 300M input shaft, RevMax triple converter, increase line Pressure " docs magic, Improve shift points " doc ."

It's a spendy road, but I would start on the trans before any power upgrades if I could do it over again.

The 68's are nice but do have several issues once power is thrown at them.

Anything you can do to keep the heat down will be the key.

I’m right there with you, tranny would definitely have to be completed first. It’s very interesting to hear about what these things are capable of. I’m new to the diesel world but damn. I wish I would have gotten into it 10 years ago


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