Tuning a stock car will not gain you a lot of horsepower. However, you can tune your stock car to make it more aggressive, responsive and remove any limitations from the manufacturer.
If you have a modern enough car, you will be surprised at how much your car is limited from its true potential.
I know there are many questions about tuning a stock car. This is where you have not installed any aftermarket parts but are interested to tune anyway.
Personally, a couple of my friends and I have dabbled in tuning for some time now. Which is why I know there are many things that a stock car can benefit from tuning.
Though I must emphasize the fact that you won’t gain a lot of horsepower just by tuning. To really gain horsepower, you need those aftermarket parts.
In this article, I am going into detail about tuning a stock car. I will cover things like
- Horsepower gain when tuning a stock car
- What can you tune on a stock car
- Will tuning damage engine
- Can insurance tell if you have tuned your car
- My thoughts
Horsepower Gain From Tuning Stock Car
By tuning a stock car, you could gain a maximum of 20 horsepower or so. This depends entirely on your car engine and model but don’t expect to gain much horsepower from tuning a completely stock car.
If your main priority is to gain horsepower, then tuning alone is not enough. You should look into aftermarket parts like headers, exhausts, or downpipes.
Each of the above aftermarket parts could yield you at least 30 horsepower with tuning. If your car has a turbo, an aftermarket downpipe is a great choice – you can even gain 50 horsepower with a less restricted downpipe and a tune.
Tuning is great to unlock the potential of a car or its aftermarket parts. However, you can’t expect to tune a stock car and suddenly gain 50 horsepower – not possible!
That aside, tuning a stock car is still greatly beneficial. Let me cover all the things you can tune on a stock car next.
What Can You Tune On A Stock Car?
When it comes to tuning a stock car, your main priority is to remove the limitation set by the manufacturer.
These are things like removing rev limiter, top speed limiter, improving throttle response, etc.
A manufacturer limiting the true potential of a car is a common thing. They generally do this for safety, better mileage and to comply with regulations.
For example, BMW, Mercedes and many other car brands limit their top speed to be 155 mph. This limiter can easily be removed by tuning.
Here’s 5 things you can do when tuning a stock car:
1. Remove Rev Limiter
Removing rev limiter allows you to rev higher than what you see in the dashboard. This makes your car more aggressive and can reach a higher horsepower reading in the dyno.
I personally don’t recommend removing the rev limiter because revving too hard can shorten your engine life – specifically the engine, pistons and even transmission.
Also, revving too hard and too often can significantly reduce your gas mileage. I assume you are researching for your daily driver! Which is why I think it’s a bad idea.
But if you are looking to tune your track or weekend car, then I think removing the rev limiter is okay – it can be super fun!
2. Remove Top Speed Limiter
Removing speed limit allows your car to go faster than what’s allowed by the manufacturer. This can easily be done by tuning because the speed limiter is set on the ECU level.
This makes a lot of sense if you are driving in places where there’s no speed limit – think of tracking or even the autobahn in Germany.
Car manufacturers put a speed limiter on their cars for safety and to comply with regulations in the countries.
Removing the speed limiter allows you to immediately unlock your car’s full potential – without getting any aftermarket parts.
This of course depends on the car model. Many cars don’t have such speed limiter but modern cars from BMW and Mercedes do have this top speed limiter at 155 mph.
3. Update Engine Torque Map
Updating engine torque map allows you to control the torque output produced by your car at any RPM- including accelerating or downshifting. This means you can have a more aggressive car.
In modern cars today, the gas pedal is not mechanically connected to the throttle body. It’s all calculated by computer to ensure your driving experience is smooth and consistent.
Typically, you gain more power and acceleration as you go at a higher RPM. If you haven’t noticed yet, try hammering your gas paddle at 0 RPM.
Your car will not suddenly accelerate to match your gas paddle. Instead, your car’s computer will produce the acceleration gradually as you go higher RPM.
All of these values and actual torque output can be adjusted through the engine torque map.
For example, you can increase the torque output at lower RPM – allowing you to accelerate harder after every corner. Very useful if you are driving up the mountain and need that extra acceleration at lower RPM.
All of this is possible without any aftermarket parts – just tuning.
4. Improve Throttle Response
You can improve the throttle response significantly by updating your car’s engine torque map.
Earlier I explained to you how your gas pedal is not mechanically connected to the throttle body. Instead, the car’s computer calculates how much torque you should get based on the current RPM and your gas pedal.
By tuning your car, you can update the engine torque map and make your throttle more sensitive. Which means, you gain a power burst every time you step on the gas pedal.
Just instruct your tuner to give you more throttle response on the lower RPM. Trust me, you will love this. But you have to get used to the new throttle response. Be careful on the first day!
5. Adjust For Slightly Rich Air/Fuel Ratio
With tuning, you can adjust your car’s air / fuel ratio to be slightly richer. This is great for performance but can reduce your gas mileage.
Every stock car from the factory is configured to have the optional air / fuel ratio of 14.7 : 1. This provides you with a balance of power, gas mileage and emission.
If you think power is more important than gas mileage, then you can tune your car to be slightly rich. Not too rich because that will cause other problems – but just slightly.
By having a slightly richer air / fuel ratio you ensure there’s an abundance of fuel in the combustion chamber. Which means every combustion that happens is more likely to be powerful and optimal.
Consult with your tuner on how rich you should go. Different engine sizes have different configurations. I believe an experienced tuner should know about this because tuning for a slightly rich air/fuel mixture is not uncommon.
Will Tuning Stock Cars Damage The Engine?
Tuning stock cars will not cause any engine damage if done correctly. However, gas mileage and emission can be made worse. Occasionally, you may also get Check Engine Light.
If done correctly, the true potential of your car will be unlocked. Which typically means more power and responsive car but worse mileage.
In return, emissions can be made worse if you tweak your car engine to run richer. Slightly richer will be fine though. The extra emission is minimal and it will be legal.
You may also get Check Engine Light because the car’s computer is not expecting the change in behavior. If your tuner is experienced, he should also be able to turn the CEL off – so this is not a big problem.
Technically, you can tune your car to be less powerful in order to achieve better gas mileage. However, as a car enthusiast, I assume power is what you want… yes?
In this article, I am only discussing tuning to get more power. The topic of tuning for better mileage should be a new article on it’s own.
All in all, don’t worry about engine damage because of tuning. That will not happen. Unless your tuner made a huge mistake or significantly skewed your configuration. In this case, you need to get a better tuner.
Is Tuning A Stock Car Legal?
As long as the tuned car is still compliant with sound and emission laws, tuning a car is legal. Even better if the tuning is done by a certified tuner.
Tuning becomes illegal only if you go overboard with it. For example, tuning your car to be extremely rich – causing it to produce highly toxic exhaust gas.
If your car is tuned by a certified tuner, then it’s definitely going to be legal. The tuner should know what’s legal and what’s not.
I recommend consulting with the tuner and checking your local laws to be sure.
Can Car Dealers Tell If You Tune a Stock Car?
Car dealer will know if your car has been tuned. Depending on how you tune, the actions you do are typically logged in the car’s computer – allowing dealers to know what you have done.
One idea is to tune your car back into the stock settings before bringing it to the dealer. Some dealers will still not accept it while others may just shrug it off – as long as it’s in stock settings.
It depends entirely on your relationship with the dealer.
My recommendation: If your car is quite new and still has a warranty, I suggest you wait a little longer before you tune. Enjoy your car while it’s still kinda new before you get dirty with it.
Cost To Tune A Stock Car (& Is It Worth It?)
Tuning usually starts from $600 and goes even higher to $1,000 depending on the configurations you require. You will also be charged for the dyno runs at typically $150 per pull.
Tuning means updating your car’s configuration to fit your needs – may it be performance or gas mileage. This costs $600 – $1000 depending on what you need.
For example, if your car doesn’t support flash tune, you may need to get a new flashable chip that costs even more.
Dyno means testing your car to see readings like horsepower, torque, air/fuel ratio and others. This costs about $150 per session. You typically need 2-3 sessions.
Which means, at a minimum, tuning a stock car can run you from $900 (including dyno) to $1,500.
That’s steep! But it can be worth it if you are a true enthusiast who will enjoy the power or any custom configurations that you put in.
Should You Tune a Stock Car?
Personally, I wouldn’t tune a stock car. It costs too much for no actual horsepower gain. Instead, I recommend installing aftermarket parts and then going for a tune – this is the most effective.
I suggest saving up your money and installing these parts below:
- Cold air intake
- Aftermarket headers
- Aftermarket downpipe
- Aftermarket catback exhausts
Once you have all of these installed, then go for a tune. I guarantee you are going to get monster performance and sound improvement.
I expect to gain a total of 70-100 horsepower with all of these parts installed.
And they cost a lot. This is why car modification is a progress. You do not just do one thing and expect to gain real performance.