GM Family II Tuning

"All you need to know about tuning the GM Family II engine!"

Now we shall detail the best approach to Family II tuning and show the premier modifications. GM Family II have loads of potential and with the right motorsport mods like remapping, turbo upgrades and camshafts you will positively enhance your driving experience.

History of the Engine


  • 16LF
    72 hp (53 kW ) @5200 rpm (Ethanol) 73 hp (54 kW) @5400 rpm (Petrol)
  • 16SH
    66 kW (90 PS; 89 hp) @5800 rpm
  • 16D
    40 kW (54 PS; 54 hp) @4600 rpm
  • C16NZ2
    55 kW (75 PS; 74 hp) @5200 rpm


  • 17D
    42 kW (57 PS; 56 hp) 105 Nm (77 lbft) @2400 rpm
  • 17DR
    44 kW (60 PS; 59 hp) 105 Nm (77 lbft) @2650 rpm
  • X17DTL
    51 kW (69 PS; 68 hp) 132 Nm (97 lbft) @2400 rpm


  • 18E
    85 kW (115 PS) @5800 rpm 151 Nm (111 lbft) @4800 rpm
  • C18LE
    70KW (95HP)
  • 18N
    62 kW (84 PS) @5400 rpm 143 Nm (105 lbft) @2600 rpm
  • 18S
    66 kW (90 PS) @5400 rpm 143 Nm (105 lbft) @3000–3400 rpm
  • C18NV
    74 kW (100 PS) @5800 rpm
  • C18NZ
    66 kW (90 PS; 89 hp) @5400 rpm 145 Nm (107 lbft) @3000 rpm
  • LH8
    63 kW (84 hp)
  • LA5
    112 kW (150 hp)


  • 20NE
    115 PS (85 kW) @5200 rpm 175 Nm (129 lbft) @2600 rpm
  • 20SE
    122 PS (90 kW) @5400 rpm 175 Nm (129 lbft) @2600 rpm
  • 20SEH
    127–130 PS (93–96 kW) @5600 rpm 180 Nm (130 lbft) @4600 rpm
  • C20NE
    115 PS (85 kW) @5200 rpm 170 Nm (130 lbft) @2600 rpm
  • LT2
    96 hp (72 kW) 160 Nm (118 lbft)
  • LE4
    110 hp (82 kW) @5200 rpm 167 Nm (123 lbft) @3600 rpm
  • LT3
    165 hp (123 kW) @5600 rpm 175 lbft (237 Nm) @4000 rpm
  • C20XE
    115 kW (156 PS) 203 N⋅m (150 lbft)
  • C20XE
    110 kW (150 PS) at 6000 rpm 196 N⋅m (145 lbft) at 4600 rpm
  • C20LET
    150 kW (204 PS) at 5600 rpm 280 N⋅m (207 lbft) at 2400 rpm


X20XEV 136 PS; 134 hp (100 kW) 185 Nm at 4000 rpm
X20XER 160 PS (118 kW) 188 Nm at 4300 rpm
Z20LET 147 kW (200 PS) 197 lb⋅ft (267 N⋅m)
Z20LEL 125 kW (170 PS) 193 lb⋅ft (262 N⋅m)
Z20LER 147 kW (200 PS) 193 lb⋅ft (262 N⋅m)
Z20LEH 177 kW (241 PS) 236 lb⋅ft (320 N⋅m)
U20SED (L34) 119–132 hp (89–98 kW) at 5400 rpm 126 lb⋅ft (171 N⋅m)



  • C22NE 123 hp
  • C22LE 116 hp
  • X22XE
    100 kW (130 hp) @ 5200 rpm, 104 kW (139 hp) @ 5400 rpm
  • Y22xe
    106 kW (142 hp) @ 5400 rpm Torque: 205 N⋅m (151 lbft) @ 4000 rpm
  • Z22xe


  • C24SE – 2.4 L SOHC
  • X24XF— 2.4 L
  • X24SFD 150 hp @5200 rpm 228 Nm @4000 rpm
  • Z24XE FlexPower (134–138 hp) @5200 rpm 160 lbft @2200 rpm

Tuning the GM Family II and best Family II performance parts.

Best Family II modifications

When talking about the best top for your Family II engine, we are going to concentrate on the modifications that give the best power gain for you money.

Altering your Family II cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

Fast road camshafts normally bump the performance through the rev range, you could drop a little bottom end power but your higher rpm power will be better.

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

A Motorsport cam will just annoy you whilst driving in heavy traffic.

You should ideally match your engines power to your cars usage so for a daily driver stick with a mild fast road Family II cam

Some Family II engines respond better to less aggressive camshaft durations so view each engine as unique.

The engine timing and fuelling also will make differences on the torque gains you'll hit.

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.

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

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

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

Plan your options and then buy your tuning mods and set yourself a power target to avoid wasting your time and money.

ECU mapping should help to to establish the full potential of all the modifications you've fitted to your Family II.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage usually vary depending on the modifications you've fitted and the condition of your engine.

Shoving more fuel and air into the Family II engine is the main goal to any engine upgrade job.

Intake take the air from the filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

Design and flow characteristics of the Intake headers can make a noticeable difference to to fuel mixing and power on the Family II.

I usually find plenum chambers are in dire need of an upgrade, although some OEM provide well optimised plenum chambers.

Larger Family II valves, doing some port matching and head flowing will also lift torque, and significantly will afford you a greater torque increase on other parts.

Turbo upgrades

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 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 significant power gains.

When an engine is fitted with a turbo tuning parts are going to net you a larger power gain and we find turbocharged engines already contain many forged and stronger components.

However every engines will have power limits

Research these limitations and upgrade to better quality crank and pistons to cope with the power.

It's not unheard of drivers spending a lots of money on turbocharger upgrades on the Family II only to watch the engine catastrophically fail on it's first outing after it's been enthusiastically driven.

Larger capacity turbochargers commonly experience no power at low rpm, and smaller turbochargers spool up really quickly but don't have the top end bhp gains.

In recent times the selection of turbo units is always improving and we are seeing variable vane turbo units, permitting the vane profile is altered according to speed to lower lag and increase top end power.

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

It is common that there's a limitation in the air flow sensor AFM/MAP on the Family II when considerably more air is being pulled into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited torque at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more complex to get working. We have this article covering twinchargers if you want to read more.


You will need to ensure that the engine is not starved of fuel so will need to pay attention to the fuelling when you start going beyond 20% of a torque increase.It is important to be generous with your flow rate on the injectors.

As a rule of thumb add 20% when fitting an injector, this accounts for injector deterioration and affords some spare capacity should the engine require 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

  • 58 PSI 340cc/min 200hp
  • 58 PSI 511cc/min 300hp

4 Cylinder NASP engines

  • 58 PSI 285cc/min 200hp
  • 58 PSI 426cc/min 300hp

4 Cylinder supercharged engines

  • 58 PSI 312cc/min 200hp
  • 58 PSI 468cc/min 300hp


You only need to to upgrade your exhaust if your exhaust is actually creating a flow problem.

On most factory exhausts you'll find the exhaust flow rate is ok 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 you'll slow up the exhaust flow 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.

Typically exhaust restrictions can be located the catalyst installed, so adding a higher flowing high performance alternative will help avoid this restriction.

Weak spots, Issues & problem areas on the Family II

The Family II engines are generally reliable and solid as long as they are regularly serviced and maintained.

Regular oil changes are vital on the Family II, especially when tuned and will help extend the life and reliability of the engine.

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

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which mods work best for them on each model of car. Comments are used to improve the accuracy of these Family II articles which are continually updated.

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.


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

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).
Sign up now!!!

Popular articles

Diesel tuning
Remapping ECU
double clutching
Safety mods
Induction Kits
Customize a car
Chipping cars
Modified car insurance
Track day insurance
Diesel remaps
Work out your MPG
DPF cleaning

Alloy Wheels

Alloy wheels and their impact on handling and performance.

Diesel Remaps

Remaps for diesel engines

Lambo Doors

Lambo style doors suicide doors and gullwing door conversions.

Spray Art2

Stunning sprayed art on car body panels


Sleepers – tuning ordinary looking cars

Tuning Mistakes

Common mistakes made in car tuning

MPG Calculator

MPG calculator UK miles per Gallon – calculate MPG