Modding upgrading and tuning the Vauxhall U20SED engine!

Tuning guide "U20SED Modifications"

U20SED Modifications Guide

How to modify and upgrade the Vauxhall U20SED

"Comprehensive guide to tuning the Vauxhall U20SED engine!"

Popular tuning sites like TorqueCars are regularly seeing threads requesting information on how to improve the U20SED from people wanting to know what are the best tips for U20SED power upgrades. So let us look into Vauxhall U20SED tuning mods and outline the best mods that work on this great engine and point out some potential pitfalls along the way.

The Vauxhall U20SED are popular tuning projects and with the ultimate performance enhancements like ECU maps, turbo upgrades and camshafts you will positively enhance your driving pleasure.

In this article we consider U20SED tuning and outline the ultimate modifications for your car.

When talking about the top parts for your U20SED engine, we are going to focus on the ones that give the best value for money.

U20SED induction kits

Improving air intake on the U20SED

You need air and fuel for an engine to work. If there is not enough fuel then it will run lean, if there is too little air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing more air into the U20SED engine is the aim to any engine upgrade project.

It is not unusual that there's a restriction in the air flow sensor (AFM/MAF/MAP) on the U20SED when loads 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 torque at a much lower level.

Air Intake manifolds transmit the air during the suck phase from the air filter and allow it to be sucked into the engine cylinders.

The shape and flow characteristics of the Plenum can make a noticeable effect on to fuel delivery on the U20SED.

Many mass produced engine air intake manifolds are needing an upgrade, although some car makers provide well optimised air intake manifolds.

Increasing the U20SED valve size, getting port matching and head flowing will also lift performance, and as an added benefit will make space for raising the performance increase on other mods.

U20SED performance cam tips.

Some U20SED engines respond better to different cam durations check your engine on a rolling road.

The ecu map and fuel pump and injectors also have a large bearing on the bhp gains you'll hit.

Altering valve durations can alter the bhp 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.

Significant air intake, and exhaust improvements on the U20SED can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

NB: Fast road cams tend to push up the bhp through the rev range, you might lose a little bottom end power but high end rpm power will be lifted.

Motorsport and race cams, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Competition camshaft is not great on the daily commute.

You should ideally match your engines power to your typical driving style so for a daily driver stick with a mild fast road U20SED camshaft

Stage 1, 2 and 3 mods for the U20SED

Stage 1 U20SED parts:

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

Stage 2 U20SED parts:

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

Stage 3 U20SED parts:

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

Review your options and then source your upgrades and set yourself a power target to avoid disappointment.

Mapping helps to establish the full potential of all the parts you've done to your U20SED.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage will vary depending on the parts you've done and the condition of your engine.

Turbo modifications on the U20SED

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the U20SED.

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

If your motor is fitted with a turbo tuning mods are going to make more power and you'll see that turbocharged engines are made with uprated components.

There are reliable limits for every engine, with some being over specified and some only able to handle stock power

We recommend you find these limits and upgrade to better pistons and crank to survive the power.

We've seen people spending a a stack of money on turbo upgrades on the U20SED only to experience the engine go up in smoke soon after it's completed.

Large turbo units commonly suffer low end lag, and small turbo units spool up much more quickly but won't have the peak rpm bhp gains.

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

Twin scroll turbo units divert the exhaust flow into 2 channels and push these at differently designed vanes in the turbo. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp and torque gains, although more difficult to configure. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the U20SED

You will need to ensure that the engine is not starved of fuel so should increase the fuelling when you start extending past 20% of a torque hike. Experienced mechanics will tell you to be generous with your flow rate on the injectors.

As a rule of thumb add another 15% when specifying an injector, helps cope with injector deterioration and allows some spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended U20SED performance exhaust upgrades

We'd only recommend you look to uprate your exhaust system with an upgraded one is if your current exhaust is actually causing a restriction.

On most factory exhausts you'll see your flow rate is still ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts equal out the flow of air through the engine.

But if the exhaust pipe is too large, ie: over two and a half inches diameter, you will lose much of the flow rate and end up sapping power and torque.

Typically exhaust restrictions can be traced to the emissions filters installed, so adding a better flowing performance alternative will help avoid this restriction.

Decatting (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the U20SED

Like most engines an U20SED, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the U20SED, failure to do this will exacerbate engine wear, on a tuned U20SED this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your U20SED why not pop over to the forums at TorqueCars where you can chat about U20SED tuning options and read about others projects who may be planning to do similar modifications on their U20SED.

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