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Pro Tuning on a Shade Tree Budget


Exhaust System Testing

Khrome Werks AR-100 versus SuperTrapp 2-1

Why compare two exhaust systems?
Despite the proliferation of big inch EVO engines, there seems to be little information comparing exhaust systems for these engines. Prior testing results on 80CID engines has generally shown the ability of 2-1 systems to provide better power than 2-2 systems. There is a new crop of large OD 2-2 pipes for big inch and high power engines. Nightrider decided to test one of the better 2-2 pipes available against the de-facto standard of 2-1 systems.

Khrome Werks AR-100
Khrome Werks manufactures their "AR 100" line of 2-2 pipes. The AR 100 exhaust system is a 2" OD exhaust system that uses Khrome Werks patented anti-reversion technology to improve power. The AR 100 pipes are one of the best engineered and manufactured exhaust systems on the market today. The quality of the chrome is superb. Fit and finish on the test pipes installed on the 94 FXDL test bike was excellent.

SuperTrapp 2-1
The SuperTrapp 2-1 system is a tried and tested system that has been used by Nightrider in most of its performance projects over the past 6 years. This exhaust system consistently sets the standards for power that other pipes are compared against. The particular exhaust system used in this test was a set of chromed pipes marketed under the Rev-Tech name.

How and what was tested?
The test methodology was simple. Run dyno comparison tests of the SuperTrapp with and without baffles against the AR 100 pipes for a total of 3 tests. Minor jetting adjustments were made to provide the best possible results, but no changes were made to ignition timing. The tests were conducted on a DynoJet 250 located at CycleRama in Pinellas Park, FL. 

Engine Specifications

3 13/16" bore x 4 1/4" Stroke
STD Cases
JIMS Crank and Rods
AXTELL cylinders
JE Flat top pistons
Crane HEV-0042 Cam
Screamin Eagle Heads modified by CycleRama - stock valve size
Compression Ratio 11:1
Mikuni HSR-45 Carburetor
Mikuni Intake Manifold modified by Nightrider
Crane HI-4E ignition module
Crane Coil

Assembly by Nightrider
Tuning assistance by CycleRama

The un-baffled SuperTrapp test was conducted because past tuning efforts have resulted in the highest horsepower and torque figures from this configuration. When the pipe is run without the baffles, the power band is quite narrow and peaky. This is a good combination for drag racing, but it is deemed unsuitable for street performance. This pipe setup is also very loud, sounding more like a race bike than a street machine.

The normal street configuration of the SuperTrapp on this engine is 21 disks and an open end cap. This configuration is also similar to those in other tests published by several v-twin specialty magazines. The power band for this setup is known to be very wide and flat, something that is very desirable for good street performance. The normal  SuperTrapp setup has always had very reasonable noise levels to it, and the typical smooth sound of unequal length 2-1 pipes. True performance enthusiast seem to like the sound while unknowing v-twin purist is more worried about the pipe not looking like they expect a Harley to look like.

The performance of the Khrome Werks AR-100 was the unknown factor in these tests. Prior testing of 2-2 pipes against SuperTrapp had generally resulted in disappointing horsepower and torque results. What the other 2-2 pipes did not have was the large diameter pipe and the AR technology. The power output of the Khrome Werks AR-100 pipes was quite unexpected and very refreshing to see.  The sound on the AR-100's is a very pleasant, low pitched rumble. These may be the best sounding 2-2 pipes on the market.

What about Twin Cam engines?
Because the test engine was a large bore EVO engine without a longer stroke and has a bathtub style combustion chambers on the heads, it is probable that TC 95 engines would see similar results with components that matched the specifications of the EVO parts.

What is our analysis of the results?
Running a SuperTrapp 2-1 without baffles is not recommended for anything other than race applications. A comparable test of the Khrome Werks AR-100 pipes without baffles was not conducted, but there is reason to believe that these modified pipes would show an increase in horsepower. Experience tells us that a set of modified AR-100's would match or exceed the horsepower produced by the SuperTrapp. The un-baffled SuperTrapp test was conducted to provide a benchmark number to compare the street configuration 2-1 and AR-100 against.

Dyno Results (charts)
bulletDyno Run 9 - SuperTrapp 2-1 with baffle removed
Max HP 116.0
Max Torque 115.3
bulletDyno Run 11 - SuperTrapp 2-1 with baffle, open end cap and 21 plates
Max HP 111.3
Max Torque 113.3
bulletDyno Run 13 - Khrome Werks AR-100 2-2
Max HP 113.4
Max Torque 110.8

The baffled SuperTrapp makes above 100 ft.lbs. of torque between 3200 and 5700 RPMs. The SuperTrapp made better power below 4500 RPMs than the 2-2 pipes. The AR-100 makes above 100 ft.lbs. of torque between 3700 and 5800 RPMs.  Above 4500 RPMs the AR-100 pipes are making 2-4 HP more than the SuperTrapp's up to the testing limits of 6500 RPMs.

How would this play out for performance?
From stoplight to stoplight, the SuperTrapp has the advantage. This is a "street" performance situation where torque rules. For dyno shootouts, high RPM roll-ons or on the Drag Strip the higher horsepower of the AR-100 pipe would win the race. An engine with a 6000-6500 RPM working RPM limit will spend very little time below 4500 RPMs. Here is where horsepower rules.

What is the recommendation?
Ignoring the performance results of a good 2-1 exhaust system is hard to do. The mid-range power potential of these systems produces a strong street machine. But there are a lot of riders out there that do not like the looks of the a 2-1 system. There is also a growing number of street/competition bikes out there that will not compromise performance for street-abilility. These are the riders that the Khrome Werks AR-100 pipes are made for. For riders that are looking for uncompromising maximum horsepower, good looks and a pleasant sound, the AR-100 is the exhaust system for you. 


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Modification, Installation, Maintenance and Tuning Index  will help you find most of the information you want on one page.

How to get Professional Tuning Results at home
Testing the Innovate Motorsport LM-1 portable air fuel meter

Profession Tuning on a Shade Tree Budget

Veypor VR2 Data Logger and Instrument Panel
Video Installation and Demo
Purchase VR2

Engine Performance
How to Build a
TC96 2007 Engines
TC88 70HP Stage1  
TC95 128HP Stage 3
TC95 100HP Street
TC96 2007 Stage 1/2
EVO 64 HP Stage 1
EVO 74 HP Stage 2
EVO 82 HP Stage 3
EVO 95 HP Stage 3
883 to 1200 Upgrade
Shovelhead Modifications

New EFI for EVO and TC

Performance Gallery
Horsepower Gallery
Evolution 80
Twin Cam 88/95
Evolution Unlimited
Sportster Unlimited
Drag Strip Gallery
Land Speed Racing Gallery
CV Carburetor
Modifying the CV carb
Tuning a CV carb
Selecting a cam
Install a TC 88/95 cam
Install a Big Twin cam
Install Sportster cams

Camshaft Specifications
Twin Cam

Exhaust Systems
EVO Exhaust Testing
TC Exhaust Testing
Khrome Werks AR100 test
Making Drag Pipes Work

Shop Manual
Carburetor Troubleshooting
Finding Manifold Leaks
Cylinder Heads
Pistons and Cylinders
Belt Drive
Shop Manual Appendix
$20 Bike Lift
Plug Wires
Spark Plugs
Engine Tuning
Nitrous Oxide
Motor Oil
Stutter Box
General Information
WEB Links
Buy Books and Manuals
Performance Calculations
Estimate Horsepower
Estimate 1/4 Mile Time
Estimate Top Speed

Engine Displacement
Exhaust Length
Gear Ratios
Air Density

The Nightrider Diaries
The ramblings of a genius a, a madman and something in between.

Where is Sifton Cams?

Autocom Active-7 tested

Harley-Davidson EFI
-EFI basics explained
-EFI modifications explained

183 HP, 2 carbs, 2680cc

Copyright 1997-2006  Stephen Mullen, Oldsmar, FL -+-