Tuning the Vauxhall C20LET

"Comprehensive guide to tuning the Vauxhall C20LET engine!"

We are regularly getting posts about the best tips for C20LET mods that work. So let us look into Vauxhall C20LET upgrades and outline the best mods that work on this great engine and point out some common pitfalls along the way.

In this article we look into C20LET tuning and outline the optimum upgrades. Vauxhall C20LET are awesome to work on and with a few sensible motorsport parts like remapping, turbo kits and camshafts you will positively enhance your driving pleasure.

When talking about the top parts for your C20LET engine, we are going to focus on the tuning mods that give the biggest return for your cash.

Altering your C20LET camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

NB: Fast road cams commonly raise the power across the rev range, you might lose a little low down bhp but the higher rpm power will be higher.

Race cams, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a car used daily one should, ideally, try to optimize your power band to your preferences.

You will never find a C20LET Motorsport cam is a pleasure to live with when on the daily commute.

Different C20LET engines respond better to mild cam durations so set your engine up on a rolling road.

The engine timing and fuel pump and injectors also will make differences on the torque gains you'll get.

Extending exhaust or intake durations can alter the torque band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

Please watch TorqueCars Video tutorial on car tuning. And be sure to subscribe and support our new channel.

Guide to the Best C20LET Tuning Mods & Upgrades

  1. Mods that Remove a Restriction

    A restricted intake or exhaust will have an impact on your car's performance, so use an induction kit/filter upgrade and better flowing exhaust whenever your tuning creates a flow restriction.

  2. Mods that Improve Handling

    Braking, Suspension and general alignment of the suspension components is vital for any tuning project even before you start increasing power.

  3. Fit Stronger Parts

    Tuned cars will show up weaknesses, typically in the turbochargers, clutch and internal engine components. Whilst most engines can cope with mild tuning mods, TorqueCars recommend that you upgrade the internal components before these weak spots manifest themselves.

  4. ECU Tunes & Remapping

    While some cars can be easily remapped, others may require piggyback ECU's or aftermarket ECU's but this is the most vital step of your tuning project as it fully releases the power from all of your mods and upgrades. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  5. More Power Needs More Fuel & Air

    Every tuning project will aim to increase the air supply, but fuel supply is just as vital and will need to match the air the engine can utilise. Fuel to Air ratio is vital so upgrade the fuel pump & injectors. Also you can look to perform head mods (flowing and porting), bigger valves, fast road cams and forced induction upgrades to improve fuel.

C20LET Tuning Stages

Stage 1 C20LET modifications: Fast road camshaft, Remaps/piggy back ECU, Sports exhaust manifold, Intake headers, Drilled & smoothed airbox, Panel air filters.

Stage 2 C20LET modifications: fuel pump upgrades, induction kit, Ported and polished head, Sports catalyst & performance exhaust, Fast road cam, high flow fuel injectors.

Stage 3 C20LET modifications: Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Competition cam, Crank and Piston upgrades to alter compression, Twin charging conversions.

The C20LET engines are great to work on and thankfully there is a lot of mods and tuning parts around.

ECU flashing allows a tuner to to establish the full potential of all the tuning mods you've done to your C20LET.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved often depend much on the tuning mods you've fitted and the condition of your engine.

It is the whole point to any tuning project to feed air into the C20LET engine

Headers take the air during the suck phase from the intake filter and allow it to be sucked into the engine cylinders.

Design and rate of flow of the Air Intake manifolds can make a substantial difference to to fuel atomisation and engine efficiency on the C20LET.

It's not uncommon that intake manifold are needing motorsport parts, although some car makers provide well optimised intake manifold.

Big valve conversions on the C20LET, doing a bit of C20LET port enlargement and head flowing will also increase bhp and torque, & more importantly will make space for a better bhp and torque increase on other tuning mods.

Turbo upgrades for the C20LET

NASP engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your C20LET

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

If your car is fitted with a turbocharger upgrades are more reliable and you'll see that turbocharged engines are made using uprated components.

There are weak spots for every engine, with some being extremely strong and some only able to handle stock power

Research these limits and fit stronger pistons, crank and engine components to survive the power.

It's not unheard of guys spending a loads on turbocharger upgrades on the C20LET only to suffer the humiliation of seeing the engine block go up in smoke when it's been completed.

Large capacity turbos commonly experience no power at low rpm, and little turbos spool up quickly but do not have the peak end torque gains.

In recent times the choice of turbo units is always improving and we commonly find variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo units divert the exhaust flow into two channels and direct these at differently angled vanes in the turbo. They also increase the scavenging effect of the engine.

It is common that there's a restriction in the air flow sensor (AFM/MAF/MAP) on the C20LET when a lot more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more difficult to get working. We have this article on twincharging if you want to read more.

Uprating C20LET fuel injectors

You will need to ensure that the engine is not starved of fuel so should uprate the fuelling when you start exceeding 20% of a performance increase.It is important to be generous with your injector capacity.

The rule of thumb is to add 20% capacity when buying an injector, this takes into account injector deterioration and gives you some spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Best C20LET performance exhausts

You only need to to upgrade your exhaust if your exhaust is creating a restriction in flow.

On most factory exhausts you'll find the exhaust flow rate is still fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the largest exhaust you can get this will slow the exhaust rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions are traced to the catalyst installed, so adding a freer flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the C20LET

The C20LET engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the C20LET, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your C20LET engine please join us in our friendly forum where you can discuss tuning options in more detail with our C20LET owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our C20LET guides and tips are kept up to date.

Please Check out my YouTube channel, we're regularly adding new content...

PLEASE HELP: I NEED YOUR DONATIONS TO COVER THE COSTS OF RUNNING THIS SITE AND KEEP IT RUNNING. I do not charge you to access this website and it saves most TorqueCars readers $100's each year - but we are NON PROFIT and not even covering our costs. To keep us running PLEASE Donate here

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Feedback - What do You Think?

Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article, I really want to improve this article with your help and suggestions.


Please watch this video and subscribe to my YouTube channel.



Member Benefits

Join our forum today and benefit from over 300,000 posts on tuning styling and friendly car banter.

You will also have full access to the modifed car gallery, project car updates and exclusive member only areas.

(All car owners of all ages and from all countries are welcome).