Overview
The intent of this chapter is to prepare you for my full-proof, ass-ripping tuning process (henceforth known as “the Process” ) by ensuring your vehicle and it’s properties are prepared to get busy. Additionally, I provide the 10,it000 foot view of the process….but here’s the beautiful thing about that, sir.
More than half (50%+) of the people reading this will go right to “Steps” below, it won’t work for them, they’ll think “ehhh!” and move on to something else. The only way Steps below will work is if all the prerequisites are met, and lady luck/the RC Gods (whomever) is smiling down upon you. Otherwise, something will be off, and this guide’s intent (as a whole) is to provide a deep dive in to troubleshooting tuning issues. Anyone can write “Do x, y, and z. Tuning complete”
The #1 rule to this guide: you cannot cut corners. Everything must me followed to a T.
Regardless, the actual steps to the Process are below. The total turnaround time for a tuned engine using this process is ~10 minutes with a heat saturated engine.
Prerequisites
- Ensure you have good traction and are properly taking advantage it via your clutch system.
- Ensure the fuel delivery system is tight and flowing consistently.
- All gaskets are in prime condition and there are no ‘leaks” in the pressure system.
- The fuel is not spoiled.
- The fuel is correct for the engine. ,e.g. If running a Nova, which recommends 25%, don’t run 16% “basher fuel”.
- The needles are at ‘stock setting’. This means any setting that will allow you to safely start the engine in a rich condition.
- Idle-stop is about .75-.1.00 mm open. Usually the size of a paper clip.
- The pipe is not a liability for that engine. The pulses in the pipe should be aligned with your engines RPMs (i.e. not too slow or not too fast).
- Don’t be afraid of damaging your engine during the tuning phase by leaning it out. Most engine damage I have seen has through running the engines too rich for too many gallons.
Steps
Step 1: Warm Up
At least one tank. It sucks, I know. But it is needed. Just give it WOT until it runs out of fuel. Some engine/vehicle combinations might take longer (chassis type, friction, etc)
Step 2: Analysis
Toward the end of the warm-up tank and/or on the second tank, take a good listen at the tune as is. It should be:
- Extremely rich
- Rough transition from low-end to high end
- Take a long time to go through its RPM range
- Idle bouncing everywhere.
NOTE: This is important as you now have a base state from which to start.
Step 3: Lean HSN
Begin leaning HSN 1/4 turn. Give the car some high speed passes. Do this until you start to hear a significant change in the RPMs as you go WOT. Then begin turning it 1/16 and run hard passes. Continue this until you hear the engine scream. Once it screams, lean it (that’ right, lean) it 1/24 until it no longer screams. i..e You’ve leaned it to the point it regresses.
Step 4: Richen the HSN:
Now richen it 1/16 turn. Don’t worry, we are not complete with this yet, but it’s a baseline. The engine should be making that chewbacca sound.
Step 5: LSN Analysis
Now you want to focus on the LSN. Lean the LSN 1/16 and do hard passes. You are looking for crisp acceleration and quick puffs of smoke. The RPM range should be smooth and consistent in its rise. Next listen to the engine idle. It should idle high for 3-5 seconds then drop. Keep leaning LSN until the engine can idle for ~10-15 seconds before dropping.. At this point your engine idle will be high. This is fine, as long as it is consistently
Step 6: Re-address HSN
By this point your ballistic RPMs should be carrying after you let off the throttle, so richen your high end 1/32 – 1/16. Get it to the point where it screams but does not starve for fuel once carb closes.
Step 7: Adjust idle
With the idle now running high off WOT for 10-15 second, close the idle gap until the idle it low, but reliable.
NOTE : Pay attention to link setup here. Often if the link is not parallel with the ball stud, the carb will close .05mm at neutral but completely close when brake is applied, thus choking the engine.
Step 8: Troubleshoot
Chances are good the engine will not be race-tuned by this point. This is due to the variables that can introduced (that’s simply how it is). Using this tuning guide (Appendix A: How to Fix This, and Appendix B: How To Fix That), you can address the state your engine might be in. The good news is you are close to being race-tuned, AND you have a known state we can address.
Step 9: Get Busy
No elaboration required.
Analysis
As per Step #2, I employ the following exercises to ascertain the “State of the Engine” (See Chapter 4: Before You Do Anything Else, to understand how states are the heart of this tuning process.
- Did I eff something up? If you recently cracked open your engine, always consider this, But how can you tell? Find out later in this guide. For now, just understand it’s part of the initial analysis.
- How are the ancillary items? Pipe, fuel delivery system, clutch….are they properly working?
- Set up….is it preventing the engine tune? As an example a clutch that is working, but improperly tuned. Or, incorrect tires, preventing any sort of traction, etc.
- Does it properly react to change? When I lean the HSN does it endeavor to hit that top note? Or, when I lean the LSN does it gain some pop?
