by Eric Perez
How do we get a Novarossi
Slide valve engine installed on the Traxxas Nitro-4-TEC or HPI RS4? The
modifications shown here will let you successfully get more ponies into
your ride. Note: This won't make your car any easier to drive. If you have
any weak drive train components or a questionable belt it will show itself
in the first couple of runs with this beast of an engine. Make sure your
rear belt is not loose, or you'll break it in a hurry. We want the rear
belt snug, not tight. The rest of the car seemed to stand up well to the
Okay, now that you've seen the pictures lets explain what to do. First follow the instructions from the traxxas/HPI web site on how to install the Novarossi engine on the chassis. To summarize things a bit:
Note: the following is a summary of how to convert the long-shaft Novarossi to short-shaft. The Nitro 4-TEC uses a short crankshaft engine. HPI touring cars use std length (also called std. airplane length) crankshafts.
1. Install clutch on engine
and determine the excess amount of crank shaft that you need to cut to
attach the clutch nut snug with the fly-wheel.
Steps 4-8 for Traxxas Nitro 4-TEC only.
4. Take engine mount and
cut the center section out. You can use a hack saw, band saw, precision
saw or dremel. Clean the cut with a file or sand paper.
This finishes the engine portion of the instructions.
Now for the not so obvious steps.
8. For the slide to work properly you need to grind off a small groove on the upper fuel tank rail. This is the plastic part that surrounds the fuel tank. The slide valve will interfere with the lip just under the slider. Remove a little plastic at a time from the fuel tank rail, until the slider will go over the lip without making contact with it. Note: You will be close to the tank, if your dremel or exacto blade slips you could damage the fuel tank. Work slowly and don't over do it on the cutting job.
The remaining steps are for both Traxxas and HPI touring cars.
9. Assembling the slide linkage:
Cut the servo horns so that they resemble Mr. T "I pity the fool". Drill out holes on the servo horn to fit the rod guides. Make sure the holes are large enough so the guides can rotate freely. Note: Exact length based on the N-4-T for HPI cars cut linkages 1/2" longer and trim to fit. Cut one of the push rods so that it has 1/2" of threads showing and is 2 1/4 " long. Attach the ball end and the collar, then the spring. Slide it into the guide and secure with another collar. Now cut the remaining rod so that it has 1" of threads showing and is 5 5/8 " long. Thread the plastic nut into the rod and slide a piece of fuel tubing. Remove the brake cam wire from the shaft and insert it behind the fuel tubing. Now insert the rod end into the remaining guide and slide a collar at the other end of the slider. see picture.
10. Remove the throttle servo from the chassis rotate it 180 degrees and re-install.
11. Attach the linkage to the carburetor and the cam lever on the brake shaft. test radio for proper throttle and break function. Re-adjust linkages as necessary, use pictures as a guide.
hope this helped. As stated earlier you may need to re-tune your chassis because the car will handle different. I suggest increasing shock oil wt by 10 to tame chassis roll down a bit. If your previous engine was a slouch you may also need to re-calibrate your trigger finger :)
Whoop some R/C Butt!!!
This page last modified: 07/26/11