Next stop (Part 2) is the airbox.  We’re going to free up a little airflow and add a bit of fuel to see how much performance lurks in the bowels of that black plastic mouse trap.  I think some of you will be surprised.

Once the airbox is optimized, we will focus on the exhaust system.
 
After the exhaust system, maybe the carburetor or possibly the flywheel.  Give me some feedback to help decide which one to test first.   One costs money, the other needs special tools.

I hope some of you find this project informative and can use the data I collect to help make decisions on your own project.  If you have suggestions or comments on my test methods, post a reply so we can discuss.   As mentioned earlier, if you have a particular component or modification that you would like to see included, let me know and we can collaborate.

Best regards, Mike

The second gear test went well.  The stocker pulled 4K to 7K in 4.60 seconds.  No glitches, air/fuel ratio was in the mid twelves.  It was safe to forge ahead.

The third gear test didn’t go as well.  It couldn’t pull 7K in third.  It signed off at 6700 rpm.  I will have to lower the timing point for the baseline and initial tests until I reach a level of modification where “the little engine that could” can pull past 7000 rpm.  For now, looks like we will have to settle for 6500 rpm.  So, the stocker pulled 4K to 6.5K in 10.48 seconds.

The fifth gear test went a bit better.  The stocker pulled 3.5K to 5.5K in 22.43 seconds.  Hey, at least it made it to 5.5K.  I must admit, the video was painful to watch.  The showroom sled signed off completely at 5500 rpm.  It simply wasn’t going any faster.
 
In the interest of fairness, I figured I should reduce the fifth gear timing threshold too.  It does a lot better if you stop the timing at 5000 rpm (about 75 mph).  So, similar to third gear, I will be using a lower threshold for the initial fifth gear tests.  The timing points will be 3.5K to 5K until I reach a level of modification where the thing can pull past 5.5K.   The stocker does 3.5K to 5K in 9.47 seconds.

There you have it.

The box-stock Savage baseline is:

Second gear 4K to 7K = 4.60 seconds

Third gear 4K to 6.5K = 10.48 seconds

Fifth gear 3.5K to 5K = 9.47 seconds

Fifth gear 3.5K to 5.5K = 22.43 seconds

All that was left were the performance tests to see what this econo-cruiser could do.  The test plan was to do timed pulls in second, third and fifth gear.  Each pull would be performed in the same location (Secret DBM Closed-Course Test Track).

The second gear pulls are intended to get a feel for how the thing is running.  I start the pull about 3000 rpm and stop about 7500 rpm.  Then I review the video and use a stopwatch to time acceleration from 4000 rpm to 7000 rpm.  If the second gear pull isn’t clean, or if there’s a significant disparity (like grossly lean fuel mixture), no sense forging ahead with the taller gears.

The third gear pulls are a measure of all-out acceleration.  These pulls are much easier to time, and the stop-watch readings are consistent.  If there’s a change in performance, it’s obvious.  Start, stop and timing points are the same as the second gear pull.  Since it’s an all-out test, I crouch down out of the wind (get under the paint) to maximize the performance.

The fifth gear pulls are a measure of real-world performance.  I start the pull about 3000 rpm and stop about 6000 rpm.  Timing points are 3500 rpm to 5500 rpm (55 mph to 85 mph).  Like the third gear pulls, they are easy to time, and the stop-watch readings are consistent.   I sit straight up on the bike and barge through the wind, just like you would do if you were trying to pass an 18-wheeler.  I view this test as the most instructive.  I think it measures exactly what most of us are looking for.

Look at that power curve.  Pretty impressive.  It goes flat right at 5000 rpm.  The real-world performance was consistent with the dyno data.  It was done at 5500.

Break-in consisted of two-hundred miles to seat the rings.  I observed a few things during the break-in.

It ran a lot hotter than the Wiseco Flat-top engine.  It was especially evident at steady-state operation, like on the freeway.  Nothing to be alarmed about, but it runs hotter.  Cylinder head temps were in the 310°F to 340°F range, and oil temp was in the 190°F to 220°F range.

Fuel economy was significantly lower than the Wiseco Flat-top engine.  The stocker was getting about 57 mpg.

Vibration levels were low.  The mirrors were crystal clear between 3500 and 4500 rpm.

Noise levels were exceptionally low.  I used my iPad with the NIOSH app to check the decibels at 1300/3000/4000 rpm under the exact conditions used for my muffler shootout.  The box-stock Savage whispered 52/72/76 dB.

Mechanical noise was also much lower.  Clicking, tapping and slapping seemed significantly reduced from the levels I was hearing with the forged Wiseco pistons and bigger cams.

It ran a bit erratic.  Lot’s of afterfire, popping, KaBooms, etc.  Deceleration was horrible.  It was embarrassing.  Steady-state was OK and it had decent throttle response.  As expected, warmup was not pleasant.  At least it wasn’t surging.

It was anemic, consistent with a box-stock Savage.  Three years ago, I dynoed this thing when it was totally stock.  It pumped out a blistering 30.5 horsepower at 5300 rpm  (dead nuts on the factory rating).  So now, when I do the performance tests on the stocker, the timed runs should be a good representation of what a 30.5 HP Savage can do.

It got a new set of rings.  The valves, seats & guides all looked primo.  A quick compression check pumped 160 psi, right where it’s supposed to be.  Ready for action.

With the 6-pound stocker.  What was Newton’s first law?  A body at rest will remain at rest; a body in motion will remain in motion; unless acted upon……….  The flywheel law.

The planned slowdown wouldn’t be complete without some additional rotating mass.  So, the special 3” flywheel had to go.  The 15-ounce flywheel was replaced.

A quick test on the trusty flow bench showed that the stock muffler wins the restriction contest hands down.  It pulled a whopping 46.5” H2O.  In contrast, the modified muffler pulled 42.5” and the Dyna pulled 41”.

The exhaust system just wouldn’t be complete without that special 1.3” diameter header pipe.  Looks mighty BIG on the outside, but it’s teeny-weeny on the inside.