When GM designed the new Duramax engine family, they had to think about utilizing a new transmission system. The GM had some other transmission options that could work, but high torque and horsepower levels demanded a different approach. There came Allison with its 1000 series. But another important question arose: how much horsepower can a stock Allison transmission handle?
The Allison automatic transmission can handle around an additional 100 hp. With an additional custom tune, this number can go to 130 hp. The good thing about the Allison stock trans is that it will not break down suddenly in case of a tune-up. If the transmission cannot handle HP over stock, it will display a message “incorrect gear ratio,” and the truck will go into limp mode.
Stay with us, because we will cover all the important aspects of an Allison automatic transmission. We researched how much hp can a stock Allison handle. We also covered the topic of upgrading the stock transmission and how much is it important.
How Good A Allison Transmission?
The Allison transmission started in 1909 at Indianapolis Motor Speedway. Their first products were designed for sports cars. When the First World War started they shifted production to aviation components. Later they switched focus back to the automotive industry. From there they kept their course all these years.
What can you see from this long and rich industry? Allison put a lot of focus on developing and researching new technologies. That kept them in front of their competitors. They kept their quality which earned their trannies the reputation of bombproof transmission products.
They formed a partnership with GM in 1928. and it lasted until 2007. That didn’t stop their cooperation. When GM introduced the new Duramax engine in their trucks, they needed to choose the transmission to pair it up with. Duramax torque rating, and HP on stock values demanded a proven product.
There came Allison, with their 5-speed automatic transmission. From the beginning, the Duramax uses the Allison transmission. Time has proven that this is a great partnership.
It wasn’t easy to handle 300 hp and 520 lb-ft of torque. Stock clutches, shafts, and other components had much to handle. The sheer weight of the truck combined with the towing capacity required only the best. The Allison 1000 can power up vehicles with a 14,000 lb of gross vehicle weight rating.
The variations of this transmission appear in heavy-duty trucks. They are used even in lighter military vehicles. This says a lot about the overall quality and dependability of these transmissions.
The Allison engineers are never quiet. They are constantly researching and upgrading their products. Their transmissions today can handle increases in torque and horsepower compared to 2001 models. They started with Duramax at 520 lb-ft of torque, which now can handle 910 lb-ft. In 2006, they added a sixth gear. It reduced fuel consumption and made the overall driving experience better.
In 2020. Allison passed on the production of transmissions for Duramax to GM. But, they have significant input in the research and production processes. From the looks of things, these transmissions are vastly improved and even better.
This tradition of building high-quality products always follows Allison. With their reputation, you can always expect the quality, design, and features that will fulfill your needs.
How Much Horsepower Can A Stock Allison Transmission Handle?
You can expect some improvements with the use of only the stock transmission. If you go overboard, you will be playing with fire. With prolonged use, the transmission will start to have problems.
5-Speed
The 5-speed Allison was used in Duramax trucks between 2001. and 2006. From the drivers’ experience, you can tune up the truck and get around 100 hp without changing stock parts in the transmission. In this case, keep an eye on Allison’s transmission fluid. The moving parts of the transmission need to be well-lubricated. That prevents further and faster wear and tear.
You can tune up this transmission to 500 hp using a shift kit that costs around $300. It will modify the hydraulic circuits, leading to better shift quality. If you choose this, you must modify a few parts. The stock C2 piston and return spring assembly cannot withstand this increase in hp. You would need to take the whole transmission out to do this.
6-Speed
The new transmission was introduced in 2006. The main thing is the additional gear. It brought better fuel consumption and comfier rides on the highway. It also allowed higher torque and hp stock values. Now it supports stock Duramax 360 hp and 650 pounds of torque. The new transmission allowed adding around 130 hp with the stock parts. In total, that brought almost 500 hp to a Duramax truck.
Full Build
If you want to achieve an additional 500 hp that will require a major overhaul. The first thing that needs to be addressed is the new clutch. The shift kit that we mentioned will take care of the hydraulics. The clutch needs to be made of grippier friction material.
The transmission needs to be taken out of the vehicle and dismantled. The best way to reach the 500-tuned horsepower is by installing a Stage 4 rebuild kit from PPE. The kit costs around 2,500$, and this process will be cheap if you have advanced transmission skills. This kit comes with a triple disc torque converter and pistons that allow adding additional clutches.
Full Send
To achieve more than 700 additional horsepower, you must bring in the big guns and go for a Stage 5 or even better 6 rebuild kit. With the Stage 6 kit comes G3 clutches from Alto. This clutch is made from material that can take an even better grip than the clutches from Stages 4 and 5. The Stage 6 kit also includes a valve body recalibration kit and an upgraded converter flow valve. This kit further increases the gripping power of the clutch.
All the kits from PPE come with detailed instructions. But, if you are not comfortable with your mechanic skills, it would be better to hire a professional. Replacing or upgrading a stock trim transmission is not an easy task.
Check Out Diesel Insights: Allison 1000 Transmission:
Why Do You Need to Upgrade Your Transmission?
Usually, drivers upgrade the transmission to gain better acceleration or higher levels of power and pounds of torque. A second reason is that it can prolong the work life of a transmission. Transmission made of high-quality components will work longer and better. Maybe you want to tow higher loads. That may require better transmission. In either case, it will do you good.
FAQs
What is the rating of a stock Allison 1000?
The Allison 1000 is rated for a 5,000 RPM input shaft speed capability.
What can a standard Allison 1000 engine do?
It can manage power up to class 3. Those include a 14,000 lb gross vehicle weight rating. That includes the vehicle’s weight, the passengers, and the towing load.
How hot can an Allison 1000 handle?
The Allison transmission can handle up to 240°F without damaging the components. But, if the temperature rises above 225°F, you should check the transmission fluid. Sometimes, the fluid level is insufficient, or the fluid is old and worn. Always pay attention to the temperature because high temperature is the number one transmission killer.
Final Considerations
If you own or buy a Duramax truck, you must know that it is paired with an Allison 1000 automatic transmission. Older models use 5-gear models, while from 2007. they switched to 6-gear transmission.
These transmissions are sturdy and have a long work life. They can also sustain limited horsepower increases with the stock parts. You can expect a limit of 100 hp with the factory-made tranny. If you want to reach some serious hp and torque upgrades, you must invest in at least a Stage 4 rebuild kit.
