1000 HP 6.7 Cummins Compound Turbo Build — The Complete Parts List

TL;DR: A 1000 horsepower 6.7L Cummins is a short block build with a compound turbo system bolted to it, not a compound turbo kit bolted to a stock engine. The stock 24-valve connecting rod is the wall — it is informally regarded as good to somewhere near 650 horsepower, so rods and pistons come out before the first turbo is ordered. The compound system is what makes 1000 hp survivable rather than what makes it possible: it drops drive pressure and exhaust gas temperature at the fuel rate this build runs. And the single most consequential decision happens before any part is bought — which 6.7 you start with, because the 2007.5–2010 CP3 truck and the 2019+ CP4.2 truck are two different builds with two different budgets.

Start With the Right 6.7 — This Decision Costs the Most

The 6.7L Cummins is 408 cubic inches from a 4.21 in bore and 4.88 in stroke, and it has run in Ram HD trucks from 2007.5 to the present. Confirm the bore decimal against a current Cummins service manual before ordering oversize pistons. Mechanically the block is one family. Everything hanging off it is not.

If you have a choice, build the 2007.5–2010 truck. It arrived with a CP3 you can stroke or twin, it uses solenoid injectors any reputable shop can build to a known flow rate, and it has real aftermarket coverage on pistons, rods, cams and heads. Our own catalog reflects that: those categories exist under the EARLY (2007.5–2010) SKU family and do not currently exist for the SCR or HO trucks. That is not a small footnote when the whole build is a short block build.

The 2019+ HO truck carries a second problem before you get to power. The CP4.2 pump is a known grenade — when it fails it sends metal through the entire fuel system. On a late truck a CP3 conversion is a prerequisite, not an upgrade: compare CPP-CUMMINS67-HO-CP4PUMP-INDUSTRIAL-02, CPP-CUMMINS67-HO-CP4PUMP-FLEECE-03 and CPP-CUMMINS67-HO-CP4PUMP-EXERGY-04 in CP3 pumps, and budget it as line one.

The rest of this article is written to the 2007.5–2010 truck.

The Short Block Comes First

Every 1000 hp Cummins parts list that starts with turbochargers is written backwards.

Stock Cummins forged rods on the 24-valve engine are informally regarded as good to roughly 650 horsepower before bending becomes a live risk — a field observation, not a Cummins rating, so weigh it against your engine builder's own experience. The 12-valve tolerates more, closer to 800, because of how it makes its power. Either way, 1000 is not inside the stock rod's envelope, and a bent rod at 1000 hp does not fail politely.

The piston choice is where high-boost diesel builds quietly go wrong. The 6.7 leaves the factory at a high static compression ratio — a diesel has to, to light off. Stack 60 to 80 psi of manifold pressure onto that static ratio and peak cylinder pressure climbs into territory the factory piston crown and top ring land were never asked to survive. That is the entire reason de-lipped and reduced-compression pistons exist for this platform. The Hypermax set is the high-boost answer; the Industrial Injection set is the forged street/strip answer. Confirm the compression ratio of any piston set with the manufacturer before ordering — published CRs vary by crown design, and that number is what your tuner needs.

Note what is not on that list. The factory 6.7 crankshaft stays. It is forged and it is not the limiting component at this power level; billet cranks belong to sled-pull and Pro Street engines running well past 1,500 and turning RPM a street truck never sees.

Catalog gap, stated plainly: we do not currently list main studs for the 6.7. At 1000 horsepower with a compound system, main cap fastener upgrade is a conversation to have with your machine shop, and it is not a part you can buy from us today. Confirm availability before quoting a full build.

Browse the short-block side in connecting rods, pistons and rebuild kits.

Head Clamping — Where ARP 425 Stops Being Enough

On a 500 hp truck, ARP 425 studs are the correct part and the discussion ends there. At 1000 with compounds, it does not.

ARP 625+ is a Custom Age 625 material stud with substantially higher tensile strength than the 8740-based ARP 425 kit. Confirm current published tensile figures with ARP for both — the material grade is the point. The rule the diesel industry has settled on is that 425 handles a well-tuned single-turbo truck and 625+ goes under a compound setup that will see sustained high drive pressure.

Studs alone are not the whole clamping story. Once peak cylinder pressure gets high enough the sealing surface itself becomes the limiter, and shops start fire-ringing the head — machining a groove and installing a receiver ring so the gasket has a hard mechanical seal at the bore edge. Confirm whether the Cometic part you order is meant to run with a fire ring or as a standalone MLS gasket; that decision has to be made while the head is at the shop, not after it is bolted on.

Compare clamping hardware in head studs and head gaskets; ported castings are in cylinder heads.

Air: Why Compounds, and What the Factory VGT Cannot Do

A compound turbo system is two chargers in series. Air enters the large atmospheric (low-side) charger, is compressed once, passes into the smaller manifold-mounted (high-side) charger, and is compressed again before entering the engine. Exhaust flows the reverse path — high-side first, then low-side.

What matters at 1000 hp is not peak boost. It is drive pressure. A single charger asked to make 60-plus psi is operating far up its own pressure ratio, which means it runs hot and generates enormous backpressure in the exhaust manifold to do it. High drive pressure pushes exhaust gas back past the valve, drives EGT up, and lifts the head. Splitting the same total pressure ratio across two stages puts each charger nearer the middle of its efficiency island — a cooler charge and a far better drive-pressure-to-boost ratio at the same fuel rate. That is what keeps a 1000 hp Cummins alive between passes instead of turning head gaskets into a consumable.

This is also why the factory HE351VE variable-geometry turbo comes off. A VGT's sliding vane mechanism is a spool and backpressure device designed for the factory's narrow duty cycle. It is not right for either position in a compound arrangement, and the high-side in particular wants a fixed-geometry unit with a purpose-matched turbine housing.

Catalog gap, stated plainly: we do not currently list a compound turbo kit for the 6.7 Cummins. Our compound offerings today are CPP-CUMMINS59-24V-CR-TURBOCHARGER-SMEDING-07 for the 5.9 24V common rail, plus Duramax and Powerstroke kits. The 6.7 turbochargers we stock — Fleece Cheetah 6.7 VGT (CPP-CUMMINS67-EARLY-TURBOCHARGER-FLEECE-03), Industrial Injection Silver Bullet VGT (CPP-CUMMINS67-EARLY-TURBOCHARGER-INDUSTRIAL-04), BD Screamer (CPP-CUMMINS67-EARLY-TURBOCHARGER-BD-02) — are all single VGT drop-ins, good parts in the 500–700 hp range and none of them the 1000 hp answer. Saying so is more useful than selling someone a Silver Bullet and letting them find out on a dyno. Check turbochargers and treat the compound kit as a sourced item for now.

The hardware class a 1000 hp compound 6.7 uses is an S400-family low-side — the category of CPP-CUMMINS59-12V-TURBOCHARGER-BORGWARNER-06 — paired with a fixed-geometry high-side in the 62–66 mm class. Confirm frame sizes with your kit manufacturer.

Fuel: Where a 1000 HP 6.7 Actually Runs Out

Fuel is the section where our catalog runs out before the build does, and the honest way to write it is to say so.

Three things to understand.

The injector sets we list top out below the target. A 100 HP over set and a 60% over set are good parts for 700-hp-class trucks. A 1000 hp compound build generally runs injectors in the 150–200% over class, and those are custom-order items today rather than shelf SKUs. Confirm availability before promising a complete fuel package.

One CP3 is the ceiling, and a 12mm stroker is at it. The stock Bosch CP3 runs out of volume before pressure: as nozzle size and duration climb the pump can no longer keep the rail full at the top of a pull, rail pressure sags, and a competent calibration pulls fuel to protect itself. A 12mm stroker restores that volume and at 1000 hp is working hard. Most 1000-plus builds go to dual CP3 — a second pump on an auxiliary bracket — and we do not currently list a dual-CP3 kit for the 6.7. That is a second gap in the same system.

Supply pressure is not optional. The CP3 is lubricated by the fuel passing through it. Starve it and you kill the most expensive part in the system, quietly, over months. A 165 gph lift pump here is a minimum, not a headline. Compare supply pumps in lift pumps and high-pressure options in CP3 pumps; injector stages are in fuel injectors.

Valvetrain and Cooling — the Parts Nobody Photographs

At 1000 hp the drive pressure that comes with a compound system tries to push the exhaust valve off its seat during the exhaust event. Factory springs are not sized for that.

Take the 110# high-RPM spring on a compound build, not the 103#, and take the chrome-moly pushrods with it — factory pushrods bow before the springs surrender, and a bowed pushrod at 1000 hp takes a rocker with it. The camshaft is a real improvement but a second-order one: a 188/220 grind helps the engine breathe against a compound system's exhaust characteristics, and it is worth doing while the front of the engine is apart — not worth pulling a running engine down for on its own.

Cooling gets treated as an afterthought and should not be. A compound 6.7 rejects enormous heat into the coolant and the charge air. Browse valve springs, pushrods, camshafts, water pumps and sensors.

The Three Things That Actually Break

The transmission. The 68RFE behind most 6.7 trucks is not a 1000 hp unit and no engine part on this list changes that. Budget a built transmission and converter as part of the project, or it ends in a parking lot. This is outside our catalog and is frequently the largest single line item in a 1000 hp build.

EGT discipline. A compound system buys enormous EGT headroom over a single, and builders promptly spend all of it by adding more fuel. A pyrometer and the willingness to lift are engine parts in every sense that matters.

The head gasket, if the clamping was compromised. Nearly every failed 1000 hp Cummins head gasket traces back to one of three things: 425 studs where 625+ belonged, a sealing surface that was not machined flat while the head was off, or a tune making cylinder pressure the hardware was never quoted for. All three are decided before the engine ever runs.

Frequently Asked Questions

Can a stock 6.7 Cummins bottom end handle 1000 horsepower? No. The 24-valve Cummins connecting rod is informally regarded as good to somewhere near 650 horsepower before bending becomes a real risk. A 1000 hp build requires aftermarket rods and, in practice, forged or de-lipped pistons to survive the cylinder pressure that comes with high boost. Weigh that rod figure against your own builder's field experience — it is a widely repeated observation rather than a published Cummins rating.

Which year 6.7 Cummins is best to build to 1000 hp? The 2007.5–2010 truck. It came with a Bosch CP3 high-pressure pump and solenoid common rail injectors, and it has the deepest aftermarket coverage for pistons, rods, camshafts and cylinder heads. The 2019+ HO truck uses a CP4.2 pump and piezo injectors, which adds a mandatory CP3 conversion before the build even starts.

Do I need compound turbos for 1000 hp, or can a big single do it? A large single can reach the airflow number, but only at a very high pressure ratio — which means high drive pressure, high charge temperature and high EGT. Compounds split the total pressure ratio across two stages so each charger runs nearer its efficient range. On a truck you intend to drive, that is the difference between a build that survives and one that eats head gaskets.

Will the factory VGT turbo work as part of a compound setup? No. The HE351VE variable-geometry unit is designed around the factory's operating envelope, and its sliding vane mechanism is not right for either position in a compound arrangement. The high-side in particular wants a fixed-geometry charger with a matched turbine housing.

Is one CP3 enough for 1000 hp? A 12mm stroker CP3 is working at its limit there. Most builds past roughly 1000 hp move to dual CP3 pumps to keep rail pressure from sagging at the top of a pull with large injectors. Source a dual-pump kit separately — we do not currently list one for the 6.7.

Do I need ARP 625+ head studs, or will ARP 425 work? ARP 425 is correct for a well-tuned single-turbo truck in the 500–700 hp range. At 1000 hp with a compound system and sustained high drive pressure, ARP 625+ Custom Age is the right call. Confirm tensile specifications with ARP; the material grade is the reason for the upgrade.

Does a 1000 hp 6.7 Cummins need a billet crankshaft? Not at this power level. The factory 6.7 crankshaft is forged and is not the limiting component at 1000 horsepower on a street or street/strip truck. Billet cranks are sled-pull and Pro Street hardware. Spend that budget on the fuel system.

What breaks first on a 1000 hp 6.7 Cummins? The transmission, in almost every case. The 68RFE behind most 6.7 trucks is not rated anywhere near this power. After that: head gaskets, when clamping hardware or machining was compromised, and injectors, when fuel supply pressure was neglected.

Not sure which 6.7 generation your truck is? Check fitment first — the EARLY, SCR and HO SKU families are not interchangeable on injectors, pumps or turbochargers. Browse the full engine family catalog, or start with gaskets and seals and oil pumps if the engine is already apart.