Modding upgrading and tuning the Volvo VEP4 engine!

Modifying and improving: "VEP4 Modifications"

VEP4 Modifications Guide

How to modify and upgrade the Volvo VEP4

"Comprehensive guide to tuning and performance parts on the Volvo VEP4 engine!"

Forums like the one at TorqueCars are always getting messages about how to improve the VEP4 from people inquiring about getting more power from the VEP4 and wanting to know what are the ultimate VEP4 modifications. So let us look into Volvo VEP4 upgrades and outline the best mods that work on this great engine and point out some common pitfalls along the way.

The Volvo VEP4 great bases for a tuning project and with the best uprated parts like ECU maps, turbo improvements and camshafts you will really improve your driving experience.

Car Tuning Tips will outline options for your VEP4 tuning and report on the ultimate upgrades.

Just because particular tuning mods are appear in lots of VEP4 projects it doesn't mean its worth having, we will focus on the optimum tuning mods that will give your VEP4 the best value for money to power increase.

Without us subscribing to the common myth of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

VEP4 induction kits

Improving air intake on the VEP4

You need air matched to fuel for an engine to work. If there is a lack of fuel then it will run lean, if there is little flow of air it runs rich losing power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Feeding more air into your VEP4 is the aim to any engine tuning job.

It is common that there's a limit in the air flow sensor AFM/MAF on the VEP4 when considerably more air is being fed 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.

Engine intake manifolds take the on the suck phase from the air filter and allow it to be drawn into the engine cylinders.

The bore size, shape and flow rate of the Headers can make a noticeable effect on to fuel atomisation and engine efficiency on the VEP4.

It's not uncommon that plenum chambers are needing performance upgrades, although some car makers provide decently flowing plenum chambers.

Increasing the VEP4 valve size, doing some port work and head flowing will also boost performance, & importantly will make space for increasing the performance increase on other parts.

VEP4 performance cam tips.

Some VEP4 engines respond better to different camshaft durations than others.

The ecu map and fuel pump and injectors also will say much 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.

Significant air intake, and exhaust improvements on the VEP4 can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts commonly increase the performance throughout the rpm band, you could sacrifice a little bottom end torque but your top end will be lifted.

Motorsport camshafts, increase the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a road car you need to optimize your power band to your driving style.

You will never have found a VEP4 Motorsport and race cam is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the VEP4

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 VEP4 parts:

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

Stage 2 VEP4 parts:

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

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

Stage 3 VEP4 parts:

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

The VEP4 engines are great to work on and we note that there are quite a few choices of mods and performance parts out there.

A remap allows a tuner to to establish the full potential of all the upgrades you've done to your VEP4.

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 the end result usually depend much on the upgrades you've applied and the condition of your engine.

Turbo modifications on the VEP4

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 VEP4.

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 turbo tuning mods are simpler to install and we find turbo charged engines are built using stronger components.

However you'll find engines will need better parts at higher power limits

Research these restrictions and upgrade to forged components to cope with the power.

We see many tuners spending a fortune on turbo upgrades on the VEP4 only to see the engine block explode just after it's been enthusiastically driven.

Larger capacity turbo chargers tend to suffer low end lag, and low capacity turbo chargers spool up really quickly but won't have the peak end engines power gains.

Over the last 20 years the market of turbochargers is always increasing and we commonly find variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end bhp.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more challenging to get working. We have this article on twincharging if you want to read more.

Tips about fuel supply on the VEP4

You will need to ensure that the engine is not starved of fuel so must uprate the fuelling when you start exceeding 20% of a bhp and torque hike. Experienced mechanics will tell you to be generous with your injector capacity.

As a rule of thumb add 15% to the flow rate when fitting an injector, this takes into account injector deterioration and allows a bit of spare capacity should the engine need 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 VEP4 performance exhaust upgrades

We'd only recommend you look to increase your exhaust system with an upgraded one is if your current exhaust is actually creating a flow problem.

On most factory exhausts you'll see the exhaust 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.

Please dont run with the largest exhaust you can get you'll slow the exhaust rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Usual exhaust restrictions come around the emissions filters installed, so adding a better flowing sports alternative will help avoid this restriction.

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

Faults issues and things to look out for on the VEP4

Like most engines an VEP4, 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 VEP4, failure to do this will exacerbate engine wear, on a tuned VEP4 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 VEP4 why not pop over to the forums at TorqueCars where you can chat about VEP4 tuning options and read about others projects who may be planning to do similar modifications on their VEP4.

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