Guide to performance tuning the F Series engine from Honda

"Honda F Series Tuning"

Our guide to tuning the popular Honda F Series and best F Series performance parts.

Honda smashed the 100bhp per 1000cc power barrier with the F series making it one of the best engines we've ever played with and a tuner dream.

As the F series is fitted to the S2000 we are going to focus on improving the C series of the engine.

There's no reason why you can't apply these mods to the F20A or even the F18 and improve things there but a swap to the C version makes a lot of sense, as it is so much stronger and better designed, saving you some tuning work.

We review and look at F Series tuning and provide tips on the ultimate mods that work.

History, Power & Specs of the F Series Engine

The F series is a lovely engine, very free revving and incredibly well built and solidly tuned from the factory, especially the F20C versions fitted to the S2000.

The F20C shows what is possible on this F Series block with the right head and setup, showing the way for lower power versions.

The F20C made some great power figures from the factory

  • Power: 240 bhp (179 kW) at 8,300 rpm
  • Torque: 206 Nm (152 lbft) at 7,000 rpm

The F20C1 was further improved and the rod stroke length and camshaft profile was tweaked to lower the peak power point and raise torque.

  • Power: 240 bhp (179 kW) at 7,800 rpm
  • Torque: 220 Nm (162 lbft) at 7,000 rpm

  •  1.8 L Honda F engine#F18B
  •  94–02 (Accord) VTEC

F20

  •  1988 2.0 L F20 (Accord) VTEC
  • 92–97 F20A4 (Prelude) SOHC
  • 00–05 F20C (S2000) (Japan)
  • 00–03 F20C1 (S2000) (America)

F22

  • 05–09 F22C (S2000) (Japan)
  • 04–09 F22C1 (S2000) (America)
  • 90–96 F22 (Accord/Prelude/CL/Odyssey/Isusu Oasis/Isuzu Aska) VTEC & Non-VTEC
  • 98–02 2.3 L F23 (Accord/CL/Odyssey/Isuzu Oasis) VTEC

Best F Series modifications

When talking about the best and most optimal modifications for your F18 F20 F22 Series engine, we are going to concentrate on the modifications that give the best value for money.

Instead of us falling into the common trap of the "if it's shiny and makes more noise it must be good" mentality of many car sites and tuning magazine

Significant gains can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

Fast road cams commonly increase the bhp and torque through the rev range, you may lose a little low end bhp but the higher rpm power will be better.

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

On a daily driver must carefully try to optimize your torque band to your usage of the car.

I'd never have thought a Race cam is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

Each engine responds better to less aggressive camshaft durations than others.

The ecu map and injectors and fuel pump also will make differences on the bhp gains you'll achieve.

Extending F18 F20 F22 exhaust or intake 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.

Typical stage 1 mods often include: Fast road camshaft, drilled & smoothed airbox, Panel air filters, Sports exhaust manifold, Intake headers, AEM EMS.

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

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

We would recommend that all F Series tuning projects include some attention to the valve train, installing upgrade springs and retainers (TorqueCars rate Ferrea springs for the S2000).

We recommend that you do a compression test which will help to determine the state of the engine and highlight the possibility of excessive wear.

If you measure a loss exceeding 20% then it should be investigated more fully.

A 3 angled valve job on the head will improve flow, (4 or 5 angles are better but there is insufficient room to do this effectively on the S2000 head).

The F Series power plant make great tuning projects and we're happy to report there are increasing numbers of parts and tuning parts about.

Remaps helps to establish the full potential of all the tuning parts you've fitted to your F Series.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and 15% on NASP engines, but you mileage will vary depending on the tuning parts you've done and the condition of your engine.

Feeding air into your F Series is the main goal to any tuning project.

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

Structure and rate of flow of the Air Intake manifolds can make a large change to fuel atomisation and engine efficiency on the F Series.

On popular non F22C series production engines the plenum chambers are begging for a performance upgrade, although a few car makers provide well optimised plenum chambers.

Larger F18 F20 F22 Series valves, carrying out F Series port enlargement and head flowing will also improve power, and as an added benefit will allow you to get increasing the power increase on other parts.

The F Series block can handle quite a bit of power before it needs strengthening with people quoting power figures in excess of 350bhp.

NB: The S2000 F22C series of engines is one of the best OEM setups we've seen, and aftermarket parts such as flowing the head, revising the intake and exhaust modifications do not improve things very much at all.

F18 F20 F22 Series Turbo upgrades

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

Be careful adding boos because the 11:1 compression ratio will force you to run a pathetically low boost, unless you perform some extensive engine modifications to lower the compression ratio (you should ideally aim for around 9.5:1), and you may see power figures approaching 350bhp.

A build we saw recently that hit over 400bhp at the wheels included the following popular parts...

  • NGK 7173s
  • Garrett GT3582R
  • ARP head studs
  • Apex'i race blow off valve
  • AEM 3.5 bar map sensor
  • Precision 600 intercooler
  • Walbro 255 fuel pump
  • Siemens 875cc injectors
  • Science of Speed 70mm throttle body
  •  InlinePro 3mm head gasket

If you change pistons you'll also need to change the sleeves.

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 F Series

However you will find an engines have limits especially when it comes to fuelling and reliability.

We recommend you find these limits and fit stronger pistons, crank and engine components to handle the power.

We see many guys spending a loads on turbo upgrades on the F Series only to suffer the indignity of watching the engine block explode when it's been finished.

Large turbochargers tend to experience no power at low rpm, and smaller turbochargers spool up more quickly but do not have the peak rpm torque gains.

You'll commonly see there's a restriction in the air flow sensor AFM/MAF on these engines 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 was restricting performance at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although more challenging to configure. We have a twincharger power adding guide if you want to read more.

Fuelling

Don't overlook the need to ramp up the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. We would recommend you to be generous with your flow rate on the injectors.

875cc injectors would see you reach around 450bhp

450cc injectors are good for modest boosting to around the 300bhp mark.

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

F18 F20 F22 Series Exhaust

You may need to increase your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you should find that the exhaust flow rate quite well even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Don't go with the largest exhaust you can buy this will slow up the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions can be located the emissions filters installed, so adding a faster flowing performance catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weakspots and problem areas on the F18 F20 F22 Series

The F Series engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oilthey are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

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

Watch the clutch, it's a know weakspot on tuned F series engines.

Test the compression ratio, worn engines can lose a lot of power.

If you would like to know more, or just get some friendly advice on Tuning your Honda engine please join us in our friendly forum where you can discuss F Series tuning options in more detail with our F Series owners. It would also be worth reading our unbiased Honda tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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