Duramax Cylinder Heads

Duramax Diesel Cylinder Heads

One of our latest products innovating the diesel world.  The first Duramax cylinder heads to be made from Ductile Iron to reduce head fatigue and cracking seen in aluminum cylinder heads.

These heads are stock height, stock length, and stock width. Stock intake, and exhaust bolt patterns are used for manifolds, and also all stock accesories can be mounted to the heads. Stock valve covers, and Oem injectors of your choice can be used also. Essentially it is a full replacement for the OEM heads, and well as it can be configured for full race applications. Ports can be matched to fit your existing manifolds, or we also offer upgraded manifolds as a package. As shown below mounted to a block with a stock OEM head one side and one of our heads on the other side.


Our material has been tested and proven in pulling tractors for over 15 years. Our material has seen exhaust gas temperatures of 2000 deg repetitively and continue to maintain there integrity. We have heads older than 10 years old that are still being used today, and will be competing at NTPA GN and PPL Champ Tour Events.

Our porting technology has been developed over many years, utilizing a Superflow 1080 flow bench, swirl meters, velocity probes and dyno testing. On these heads we have increased air flow from 150%-200% depending on valve size. Not only flow numbers at .500-.600 valve lifts, but flow at .150 – .300 have seen these huge increases which result in efficient power and more torque.

No Limit Heads

We just didn’t bring these to market and say here try it. We built one head and with the help of Danville Performance we put 60 Dyno Pulls on it. On the dyno we started realizing the potential as we saw a great reduction in heat build up in the motor. Multiple passes could be made back to back before the engine was too hot, and had to be left to cool. This was making a big impact on longevity and allowed the engine to hold the horse power, with out falling off.  It was then sent out on the track with John Humpe, and the Trouble Maker Pulling Team, making 50 hooks by the end of the season. That resulted in a OSTPA PPL 2nd place points finish in 2016 in the Limited Pro Stock class. The results showed great improvement over the previous cylinder heads being used. It was the first time in long time a full season much less a season with 50 hooks was able to be made with out breakage, and replacement of the cylinder heads.  After what most would say would have been at least 2 punishing seasons worth of pulling we received the heads back. The heads were in excellent condition, and required minimal maintenance to prep them for the next season.  Very happy with the performance and results of dependability, and competitiveness we are ready to help the diesel community with your cylinder head applications. Call 715-384-4422 for questions, and pricing.

These are available with many options including water jacketed versions that will be ready for the 2018 season. We are also currently working towards completing Cummins 24V and 12V heads, and are entertaining Ford Powerstroke heads as well.

Below is our offerings for the Duramax engine platform.

  • Cast Ductile Iron for Extreme Durability. Eliminate your  Aluminum Head Failures.
  • Solid Heads, or Wet Heads Available.
  • Stock to 38 mm Valve Sizes Available.
  • Stainless, Titanium, and Inconnel Valve Materials
  • Dual or Beehive Springs to meet your application.
  • Titanium Retainers.
  • Custom CNC Ported to meet your application requirements.
  • Ports can be made to fit existing manifolds such as HSP, and Wagler.
  • No Limit can also supply you with manifolds to meet your application.
  • Built for upgraded valve train components such as roller rockers, and extreme shaft mount rocker stands.
  • Material has been tested and proven in pulling tractors for over 15 years. Heads older than 10 years still being used today, and will be competing at NTPA GN and PPL Champ Tour Events.
  • Two piece design for repair-ability.
  • Heads have been dynoed for 3.0 and 3.6 smooth bore turbo pulling trucks.
  • Results have shown lower engine heat, and engines capable of making back to back runs with out horse power loss. Ours heads can make 4 back to back dyno passes with out hp loss, and the competitors can only make one pass with a 1 hour cool down.
  • Increased HP and Torque numbers over competitors during back to back dyno testing.
  • We can can meet your requirements for 2.5, Open, 3.0, 3.6, Super Stock, and Drag Racing Applications.

We Have Moved

We are happy to announce this will be our new location for No Limit MFG. We are not moving far just a couple miles. With the new building also comes more equipment, and a new employee.

Our phone numbers will not change, but our address will to 3701 Downwind Dr. Marshfield WI 54449.

Amongst the new equipment is 2 CNC Mills, Chucker CNC Lathe, Super Flow 1080 Flow Bench, 14 ft 300 ton NC Press Break, 14 x 1/4 sheer, Cylinder Head Seat and Guide equipment along with a few other pieces.

So what does this mean for No Limit customers. It means the same great quality, and service with more innovation, added services and new products.

New Services Available:

  • Cylinder head porting, and flow benching.
  • New Products for immediate sale:
  • Tractor Billet Rockers Arms for IH 466 JD 466, JD 619, Ford, Case 504, and more.
  • Billet Valve Covers for IH, JD
  • SFI Flywheels for tractors and Trucks
  • Water Injection systems
  • Air shut off gates, and billet velocity stacks.
  • Timing Gear sets, and covers for JD 466, JD 619
  • Custom SS oil pans for Tractors and Trucks. Wet sump and Dry sump applications.
  • Intake and Exhaust Manifolds for Tractors and Trucks.
  • Girdle Plates, and Deck Plates
  • Aftermarket Cylinder heads for Prostock, Limited Prostock, and Light Prostock.

What are we developing for this year.

  • Cummins 24v, and Cummins 12v aftermarket cylinder heads solid, and water jacketed.
  • Deck Plate Duramax Engines
  • Duramax Roller Rocker Arms
  • Cummins 24v Roller Rocker Arms Kits
  • Spring and valve kits for tractors and trucks.

As you can see we have a huge product offering, and we will continue serving the racing industry for many more years.

No Limit Manufacturing