As popular as the term VTEC has become in sport compact tuning and the lifestyle, many people don’t understand how it works or how to tune VTEC. Honda has used the VTEC technology for generations of vehicles now, and implemented it to maximize the efficiency and power from a small displacement engine.
The efficiency and effectiveness of the VTEC mechanism is unquestioned, and with many small displacement motors capable of achieving big power it’s the best of both worlds. Able to curb emission output and increase fuel economy, while capable of increasing cylinder head flow in a select RPM range.
Whether you are looking for all motor power or forced induction, it’s imperative that you put an emphasis on tuning, especially on stock sleeves. Knowing how to tune VTEC will go a long way in maintaining your engine’s reliability and horsepower potential. Dyno tuning is always best for either natural aspiration or turbocharger, check out our How To Dyno your Vehicle Guide here.
VTEC has two components that combine to maximize engine efficiency, one is the lift electronic control and the other is the variable valve timing. These two combine to provide two wildly different cam profiles through a hydraulic pin system that engages the big lobe and the high speed portion of the VTEC camshaft.
The VTEC cam has two separate lobe profiles, the smaller camshaft profile is called the low-speed cam and the larger the high speed cam. The VTEC solenoid switches the engine over, usually a value designated by your Honda ECU. This RPM range can vary between 2500 RPM and 6500 RPM.
The benefit for aftermarket camshafts is that the low profile can continue to be mild, while the larger profile can maximize power. This guide will help you tune your VTEC by teaching you how to tune VTEC and the VTEC crossover point.
The VTEC crossover point refers to the engagement point, and this is where we start our How To tune VTEC article. To find this VTEC crossover, you are going to want to perform two separate dyno runs with your VTEC point moved. One dyno run with your VTEC point set to 3000 RPM and the other set to 7000 RPM.
You are going to want to set your VTEC point at the intersection of both of these cam profiles. You can then use the dyno to gauge where your VTEC crossover must move. If you are making more power as the VTEC crosses over then you should lower you VTEC crossover point. Conversely if you are making less power then raise your VTEC crossover.
Because you are trying to aim for the point where both profiles intersect in torque, it’s normal to have a dip in torque before the VTEC crossover.
In stock form this VTEC range is between 5500-5700 rpm on a stock engine, 4500-4800 rpm with intake & exhaust, 3000-3200 rpm for supercharged VTEC engines. Knowing how to tune VTEC will help you determine this range, without causing damage to your engine.
What are the DON’T’s of tuning VTEC?
If you are a capable and knowledgeable tuner with experience tuning Hondas, there isn’t much to tell you here. However if you are starting out and not sure of what dangers could lie ahead by moving your VTEC point, here’s a few pointers on how to tune VTEC safely.
- DON’T ; Move the VTEC crossover point so low in the RPM band.
- If your VTEC engages too low in your RPM band, your engine won’t have sufficient oil pressure to keep things lubricated as it should. Because oil pressure is required to drive the pins through your lifters and engage the big VTEC lobe, you can cause serious damage to other areas of your engine.
- DON’T ; Move your VTEC crossover too high in the RPM band.
- Setting your VTEC crossover too high in your RPM band can result in valve float through your Lost Motion Assemblies (LMA) and cause damage to your retainers and / or piston and valve.
- DON’T ; Take your Honda to the dyno without it in the utmost perfect running condition
- Needless to say, never dyno or tune your vehicle if there’s anything at all wrong with it. Fix and resolve those issues first.
- DON’T ; Waste too much time trying to eliminate the pre-crossover dip in torque.
- If this torque dip is too severe for your tastes, try moving the crossover up in the RPM band by 100 RPM increments.
That does it for our How To Tune VTEC Guide, if you have any questions or comments please leave them for us below!