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| Issue 143 (October 2007) |
Words: James Revilla |
In the world of RC nitro, having a tuned pipe is crucial to good performance from your engine. There's just one problem: what pipe do you want? Currently there are two options to tuning your engines performance via a pipe. You can either invest in a pipe that gives you low-end punch, or select a pipe that will give you top-end rip. Of course, the goal is to find a pipe that gives you the best performance throughout the power band, and this is where the new Buku Power Exhaust System comes in. The Buku pipe is really two pipes in one. The Buku pipe has a sliding convergence cone (or "tuning assembly" in this case) that is adjustable by spring tension so you make the best use of your engine's power. This is an interesting idea that has been thrown around for years, but Buku claims to have conquered the task of creating a pipe that increases power throughout the power band. Let's take it for a spin and see how it performs.
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Features
• Fully Assembled Buku Power
Exhaust System
• Two header couplers to choose from
• Three tension springs for tuning options
• High power convergent cone
• Tuning plug to allow for easy setup and initial engine tuning
• Adjustment wrench for access to the internal components and for adjustment of the external spring tensioner
• Mounting wire included to mount the new pipe to your vehicle
HOW IT WORKS
Here, in a nutshell, is how the Buku pipe works. The pipe is composed of three elements: an outer canister (the basic pipe itself), a convergence cone (most pipes have one, but this one has the ability to slide in the canister), and an internal spring that regulates the convergence cone's ability to move. At idle, the spring tension holds the convergence cone at the shortest length, thus reducing the volume of the pipe and allowing exhaust pressure and fuel flow to be achieved quickly. This improves off-the-line throttle response. When you crack the throttle open, the convergence cone moves instantly to the full tuned length (basically a torque pipe at this point), improving low-end torque and mid-range power. The convergence cone will remain at this full length until the motor reaches the point where the extended tuned length is no longer beneficial. Once that point is reached, the convergence cone responds by reducing the tuned length (basically becoming a top-end pipe) to a point that optimizes performance of the top-end via the spring tension. This automatic adjustment happens continuously during operation and is always adjusting itself to produce maximum power from your engine. Additionally, there is an external adjustment screw that allows you to fine tune the spring tension for spot-on performance, as well as different spring rates should you need them.
Testing
On the track (outside)
I first went out and got used to my stock REVO setup. For this test I used a 2.5R REVO and since I haven't been using it lately, I went out into the street to get a feel for the stock delivery. After a few tanks I installed the Buku system. I followed the instructions, which are very intimidating with the amount of text and "advanced tuner" warning. Once I followed the steps I went back out to test the pipe. The first thing I noticed is a sound change. It's deeper and more throaty. That sound change also led to what felt like more punch. The REVO felt quicker off the line and wanted to wheelie more than it did stock. The butt dyno says the pipe made
more power. It was time to head over to the secret XRC lab and use the tools I had on hand, namely a radar gun and the X-Dyno.
Radar
The same procedure was followed for radar testing. We conducted several runs with the stock setup and followed it up with a pipe change to see if we could note an increase in power. After several runs we noted that the pipe must be interfering with our radar gun as it gave us some problems getting information right off the line, but the BUKU system did make the car much faster off the line. This is a result of more power. We did note that the top speed seemed to suffer some, but one to two MPH won't make a different when the BUKU pipe Revo is way ahead anyway.
X-Dyno Verified
Probably the most reliable data we could give is from the X-Dyno. We retuned the engine to the stock pipe and recorded the information for both setups. We got data for each and compared the two:
Stock
Horsepower: 0.72 hp @ 26,600 rpm
Torque: 31.23 oz-in. @ 20,200
Max RPM: 37,200
BUKU
Horsepower: 0.82hp @ 26,800
Torque: 34.13 oz.-in @ 18,600 rpm
Max RPM: 36,200
The results confirmed the "butt dyno" and the radar information. It's interesting to note that the stock pipe had slightly better performance at the end of the rev. This shows that the BUKU pipe wasn't tuned correctly and after testing we went back and read that we should have increased the pre-load on the spring and the top end performance would have been better. Overall, the BUKU system gave a 12% increase in horsepower, and a 9% increase in torque. That's pretty good for just a pipe swap.
Conclusion
Some will argue that it may be a better idea to upgrade the engine for the price of the pipe, but the truth is the pipe actually does what it's supposed to. It's a way to gain power across the board without changing much more than a pipe. The system also allows you to play with it a bit to get more power where you want it. BUKU doesn't suggest this setup for beginners, but I think if they take their time and understand what's going on that lots of beginners (who mostly buy RTRs anyway) will enjoy the experience from the system. They have taken knowledge from another industry (motocross) and adapted to our market. It's not race legal, but realistically you won't be running at a ROAR anyway, and the power isn't that insane to make having it an unfair advantage. We'll be trying the pipe on some other engines to see if we can utilize the advantages on others.
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HITS
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• Honest 12% gain in HP, and 9% torque (your results will vary)
• Adds a mean "grunt" to the engine sound
• Allows you to tune the pipe to the engine
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MISSES
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• Instructions are for MIT graduates
• You have to be fairly good at engine tuning
• Not race legal for sanctioning bodies
MANUFACTURER: Buku Performance Products
PART NUMBER(S): Revo Model
STREET PRICE: $109
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