Modding upgrading and tuning the GM Family II engine!

Tuners tips on "Family II Modifications"

Family II Modifications Guide

How to modify and upgrade the GM Family II

"Comprehensive guide to tuning the GM Family II engine!"

Popular tuning sites like TorqueCars often are getting emails requesting info on how to improve the Family II from people wanting to know what are the premier Family II upgrades. So let us look into GM Family II mods and outline the best mods that work on this great engine and point out some common pitfalls along the way.

This pages aim is review Family II tuning and report on the best mods that work. GM Family II offer good returns when tuned and with a few sensible performance upgrades like ECU maps, turbo kits and camshafts you will dramatically maximize your driving opportunities.

When talking about the greatest parts for your Family II engine, we are going to concentrate on the tuning parts that give the best value for money.

Family II induction kits

Improving air intake on the Family II

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

So the whole point to any engine modification job to shove more air and fuel into the Family II engine but this has a knock on effect with the air flow sensor.

It is not unusual that there is a limit in the air flow sensor AFM/MAF on the Family II when considerably more air is being drawn into the engine.

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

Headers flow the on the suck phase from the air cleaner and allow it to be drawn into the engine cylinders.

The bore size, shape and flow characteristics of the Intake headers can make a large effect on to fuel mixing and power on the Family II.

We often see intake headers are needing motorsport parts, although some manufacturers provide well optimised intake headers.

Fitting big valve kits, carrying out Family II port enlargement and head flowing will also lift power, this will raise potential for increasing the power increase on other modifications.

Family II performance cam tips.

Different Family II engines even from the same production line will vary with some working better on different setups or needing less aggressive camshaft durations, but porting and flowing the head should reduce the differences and give consistent results.

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

Altering valve 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 Family II can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the engines power and power output.

NB: Fast road camshafts tend to boost the bhp and torque across the rpm range, you could drop a little bottom end bhp but high end rpm power will be lifted.

Motorsport camshafts, boost 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 cam is not great driving in heavy traffic.

You should ideally optimize your engines power to your typical driving style so for a daily driver stick with a fast road Family II cam

Stage 1, 2 and 3 mods for the Family II

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 Family II parts:

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

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

Stage 2 Family II parts:

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

Stage 3 Family II parts:

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

Carefully think through your options and then acquire your tuning parts and set yourself a power target to avoid wasting your time and money.

Remaps allows a tuner to to establish the full potential of all the upgrades you've done to your Family II.

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 results usually differs on the upgrades you've done and the condition of your engine.

Turbo modifications on the Family II

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 Family II.

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.

When an engine is turbocharged, tuning parts are going to net you a larger power gain and turbo engines are made using more solid components.

There are reliable limits for every engine, with some being incredibly solid and some only just able to handle stock power

Research these limitations and fit higher quality components to utilize the power.

It's not unheard of people spending a loads on turbo upgrades on the Family II only to experience the motor throw a rod on it's first outing after it's been completed.

Bigger upgraded turbochargers often experience low end lag, and little turbochargers spool up quickly but do not have the peak end bhp gains.

Thanks to progress the selection of turbo chargers is always moving on and we now see variable vane turbo chargers, where the vane angle is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust flow into a couple of channels and direct these at differently profiled vanes in the turbo charger. 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 difficult to configure. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the Family II

When you improve the bhp you will need to look at to the fuel delivery.

More bhp needs more fuel. Most tuners we speak with say to over specify your flow rate on the injectors.

As a rule of thumb add 20% when specifying an injector, this allows for injector deterioration and provides 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 Family II performance exhaust upgrades

You only need to to improve your exhaust system with an upgraded one is if the current exhaust is actually causing a restriction in flow.

On most factory exhausts you should find that your flow rate is still good 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 will certainly help air flow from the engine but do not go too big or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions can be traced to the filters installed, so adding a higher flowing high performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the Family II

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

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