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Introduction
The aim of this guide is to provide an insight into the world of tuning the C20LET engine found in Calibra Turbos. The engine is on the whole very strong, with some good fundamental design characteristics. That said, there are several components that are either badly designed or restricting when you want more power.
This guide has excluded nitrous oxide as it circumvents several traditional tuning requirements (ie a standard KKK16 cannot produce more than about 300bhp without silly EGT, except when using nitrous). A further guide may follow. However, it must be said that nitrous is a very effective way of adding horsepower to any of the below setups instead of other expensive upgrades!
Any questions just ask!
Before you begin
Make sure your engine is serviced. No matter how much boost you run, no matter how many trick parts you have... you will produce LESS power than you should be if your engine is not serviced.
Make sure your plugs are in good condition and gapped correctly. Inspect and test your leads. Fit a new genuine Bosch rotor arm and distributor cap. Check the voltage at your fuel pump and make sure your cambelt, rollers, fuel filter and water pump are not due a change. Also make sure your actuator can hold the amount of boost you are wanting to create. Get a boost gauge too, and better still a wideband AFR
Stage 1, 200-250bhp, under £150
- A set of basic EDS or Vmax chips to raise the boost pressure
- Adjusted actuator to increase boost
- Regapped spark plugs if needed
Stage 2, 250-300bhp, £400-£1,000
- A set of EDS phase 2 / Vmax Evo 5 chips
- Increased fuelling from a different/adjustable FPR, and/or different injectors
- Plugs gapped to .7mm (std RS Turbo plugs are good, or NGK-BCP7EVX)
- Adjusted actuator to increase boost
- Front mount intercooler
- Upgraded AFM to turbo hose
- C20XE inlet cam (optional, but good)
- Enlarged tophat (optional, but good)
- 2.5" boost pipes (optional)
Notes: This is the best value for money level of tune for a C20LET. Big power output (270bhp+ usually) for not a lot of money. Beyond this power level you have to spend a LOT more money for smaller gains.
Stage 3 300-400bhp, £2500-£10,000
Management options
1. High level, off the shelf phase chips
Retains factory loom and ECU
No mapping needed
Chips not tailored to your compression ratio, turbo size, cam spec
2. Live mapped motronic ECU
Retains factory loom, ECU, sensors and software like cold start map
Mapped to your individual spec
Cheaper than standalone management
Not many places can live map motronic
No extra features of standalone
Needs remapping if you change your spec
3. Standalone engine management
Ultimate flexibility. Extra functions like anti-lag, launch control, nitrous control
Extra reliability of new loom
Pub bragging rights
Expensive
Your may be limited to brands based on what your preferred tuner can map
- Increased fuelling from a different/adjustable FPR, and/or different injectors
- Upgraded fuel pump
- Tubular exhaust manifold
- Upgraded turbo and actuator
- 3" downpipe and exhaust system
- Large front mount intercooler
- Silicone or metal boost pipework
- C20XE inlet cam
- Enlarged tophat
- Gasflowed cylinder head (optional)
- Fresh rebore to 86.5mm or 87mm (optional)
- 3" boost pipes throughout (optional)
Plus for reliability you NEED:
- ARP conrod bolts as a minimum, preferrably steel conrods
- Under piston oil squirters
Optional to improve reliability:
- Upgraded oil pump
- Bronze valve guides
- Solid lifters
- Blueprinted block and head
- Head stud conversion kit
Stage 4 400bhp+ £10,000+++
Management options
1. Live mapped motronic ECU
Retains factory loom, ECU, sensors and software like cold start map
Mapped to your individual spec
Cheaper than standalone management
Not many places can live map motronic
No extra features of standalone
Needs remapping if you change your spec
2. Standalone engine management
Ultimate flexibility. Extra functions like anti-lag, launch control, nitrous control
Extra reliability of new loom
Pub bragging rights
Expensive
Your may be limited to brands based on what your preferred tuner can map
- Tubular exhaust manifold
- Upgraded turbo and actuator
- 3"+ downpipe and exhaust
- Upgraded inlet manifold, large aftermarket throttle body, 3" boost pipes
- Extensively worked cylinder head
- Both C20XE cams, or aftermarket cams
- Vernier pulleys
- Fresh rebore to 86.5mm or 87mm (optional)
- Oversized valves (optional)
- External wastegate (optional)
Plus for reliability you NEED:
- Cometic headgasket (ensure mating faces are 100% flat)
- Upgraded oil pump
- Bronze valve guides
- Solid lifters
- Steel conrods
- Mains girdle (you could use an ecotec block for this)
Optional to improve reliability:
- New standard or upgraded engine mounts
- One piece steel valves
- Steel caps, double valve springs
- Blueprinted, balanced, destressed block, brand new pumps, belts, tensioners, seals etc...
- Head stud conversion kit
- Steel crank with ARP mains
- Dry sump conversion, or fully baffled sump
Did you notice?
The HUGE amount of modifications that are either essential or preferrable over around 300bhp. This is the big step at which several upgrades are needed, for diminishing returns.
Modifications to avoid
Any induction kit that is not in a sealed airbox
"Hybrid turbos" "Stage X" turbos using the standard cast manifold
Superchips, starchips, unichips
Electric superchargers
Resistor mods
ANY aftermarket ignition leads. Standard Beru ones are amazing quality. Possible exception to this is Magnecore
It's also worth noting that the standard forged Mahle pistons are extremely strong, and don't suffer from needing large piston to bore clearances like many aftermarket forged pistons do. If they are undamaged or new there is no need to replace them. Qrew will be running an estimated 700bhp on factory pistons. Likewise the factory crank, F28 gearbox and cylinder head are all very strong and capable items.
