Jan 29 2008

HighRpmRacer

Published by admin

I want a high-horsepower Mammoth 800 UTV.

I am a “performance enthusiast”, and always have been. I like to tinker. Never been able to just leave things alone, never been able to sit still for very long. I need my Mammoth to go fast down the trails, tear up the hills, power up. I haul a trailer, put heavy loads in the bed, and of course I am running the tallest tire I can put under my Mammoth 800. I want more horsepower!

My goal is to increase the horsepower on my Mammoth 800 UTV by 50%. The Mammoth 800 engine is supposed to be producing around 38-40 horsepower stock. I am shooting for a 20 horsepower increase.

Here is how I am going to get r done………

I have a long list of modified vehicles that I have tinkered over the last couple of decades and this is what I have learned so far:

My previous projects have responded to a cam change, a carburetor change or modification, and a compression increase. Follow this with some smart exhaust tuning.

  1. Cam-change - Swap out stock cam to performance “torker cam” is projected to increase 8-9 horsepower
  2. Carb modifications - will add another 3-5 horsepower. We are going to modify the stock carburetor which has a vacuum secondary. We are going to convert the secondary and modify the linkage to make it a manual secondary just like a Holley. Another couple tuning tricks will be performed on the carb and then we bolt it back on for testing on the Mammoth 800.
  3. Mill the cylinder head - to bump compression will add 10 more horsepower. The stock compression ratio is 9.5 to 1 and the water test has been done to verify the stock compression ratio. Milling the head will bump compression ratio enough to do what I want with no adverse affects to cam timing (belt) etc.
  4. Tune the exhaust - to have 4 lbs of back pressure. This engine has been checked on the airflow bench and the stock intake manifold and the stock exhaust manifold does not flow too bad for the stock set-up. The different tuning or modifications have each been checked on the dynos and the crazy thing that has been discovered is about a 4-6 hp increase when you tune your muffler to run at 4lbs back-pressure. Sounds silly but we actually have guys plumbing a “exhaust pressure gauge” in their exhaust pipes and tuning the mufflers according to the gauge readings. Again this has showed up on the dynos to add hp. Might be best to run the stock muffler with the “torker cam” etc…..the dyno will tell us. Bottom line—-no header needed for our “bottom end torque” setup.

First step was the cam change
Last Saturday evening, my mechanic buddy and myself installed the “Torker Cam” from HighRpmRacer for the Mammoth 800 engine or “Suzuki F8B” engine. The cam we chose is a low end torque cam that is a special grind using the “Cam Doctor Machine”. The cam profile used is to increase low end torque and horsepower in the lower RPM range. This is exactly the cam profile that I was looking for in my Mammoth 800 UTV engine. The cam install was very straight forward and simple to complete in a few hours following the instructions with the cam and using the 800cc shop manual. We fired up the Mammoth engine and right away noticed the nice lope at idle. We got our timing dialed in, adjusted the idle and mixture screw on the carburetor and took the Mammoth for a test drive.

HighRpmRacer Torker Cam

Definite improvement over stock! We can now break the 27-inch XTR Mud-lites loose when standing on the throttle. The Mammoth 800 accelerates faster, hooks up faster and much more crisp feeling when driving. Two thumbs up for the HighRpmRacer Torker Cam!

Next project is the carb modifications—-we will update the results when carb is installed and tuned. We will try to get dyno results from a stock machine and my modified Mammoth for comparisons soon.

Carb Update 2/1/08 ::: I have the modified carb in my hand. The vacuum pod has been removed that was connected to the secondary throttle shaft and replaced with some cool modified linkage. When the main linkage arm that your foot pedal cable attaches is opened—both bores are opening manually. Good-bye vacuum secondary. This combined with the enlarged jets and enlarged power port valve should be a huge performance increase. This carb will be swapped with the stock carb tonight and let the fun begin. Will update the results here again soon. Bolt on horsepower is the way to go!
Stay tuned for more High Horsepower Mammoth 800 UTV tuning information here!

One Response to “HighRpmRacer”

  1. adminon 26 Feb 2008 at 3:20 pm

    The Mammoth has evolved quite well to say the least during the last couple of weeks. We have installed a new HighRpmRacer Torker Camshaft, modified carb, FMF slip on exhaust, modified secondary clutch with heavy duty belt. We are quite impressed with the low end power the machine has to root the 27″ Mudlite XTRs……..We are ready to tackle the biggest hills, muddiest trails, and more to push the limits on this Mammoth 800.

    Ok, who has the dyno we can run this on??

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