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Engine Mods
Honda's K20A engine is a technicle marvel. Pumping out almost 110 bhp per litre (in jap tune), from just two litres. Not only does this engine feature multiple cam profiles (vtec) it also has variable intake cam timing allowing excellent low down torque (unlike the s2000).
THe UK CTR has a "detuned" version of the K20A engine -the K20A2. The UK CTR produces less power, but better torque. It does not rev as high and also has a more restrictive emissions system.
The K20A2 also differs internally, having less wild cams, lower compression pistons, lower-rpm optimes intake tract and the absence of a slip differential. It also has a lighter flywheel.
The K20A2 runs a little rich in stock form. This means that increasing intake efficiency can improve power. Cold air intakes work well as they do not suck in under-bonnet heat. Short ram intakes benfit from heatshields or cold-air ducting.
The aforementioned intakes can seem to reduce throttle response. Using a sealed cold airbox gives you excellent throttle response and more power. You won't get more than 10 bhp with a CAI/airbox if you're lucky.
The K20A2 exhaust is quite good, and replacing it won't help power much at all. You will need a larger diameter if you plan to tune it further though. 2.25 to 2.5 maximum unless you want to use forced induction... Good for about 5 bhp
The manifold and cat are very restrictive. However a decat pipe won't help that much. You need a proper longtube manifold which replaces the cat. The UK car must meet stricter emissions laws for 2005, and loses power as a result. Using a manifold will make from 10-15 bhp.
An ECU retune is probably required after the manifold to account for increased scavenging. All in (intake/manifld/exhaust/ecu) will leave with about 220-225 bhp max.
Uprated cams which feature higherlift and duration will help a lot from here on. Jap J20A cams will increase bhp (with ecu retunes) to about 235-240 bhp. TODA spec A improve on the K20A cams to 250 bhp and have better torque from low-mid revs. Cat Cams 902 have even better low down- but lose about 5-10 bhp compared to TODA As. TODA cams also require stronger valvesprings to allow a safe 9000 rpm re limit.
You can then help breathing a little more by adding a jap intake manifold and a larger throttle body. Makes a small difference and increases high rpm efficiency.
Getting over 265 bhp on a stock head in naturally aspirated form is going to be difficult. None produces cams at present which take advantage of cyl head work. Besides, there is no more room on the piston to accommodate bigger cams. From here its expensive forged pistons and the like...
That's 221 bhp per ton on a CTR
THe mods also increase torque by about 20%. Coupled with CTRs short gearing and light weight, makes this a very rapid car. Addition of a lightweight flywheel helps a lot too.
Honda's K20A engine is a technicle marvel. Pumping out almost 110 bhp per litre (in jap tune), from just two litres. Not only does this engine feature multiple cam profiles (vtec) it also has variable intake cam timing allowing excellent low down torque (unlike the s2000).
THe UK CTR has a "detuned" version of the K20A engine -the K20A2. The UK CTR produces less power, but better torque. It does not rev as high and also has a more restrictive emissions system.
The K20A2 also differs internally, having less wild cams, lower compression pistons, lower-rpm optimes intake tract and the absence of a slip differential. It also has a lighter flywheel.
The K20A2 runs a little rich in stock form. This means that increasing intake efficiency can improve power. Cold air intakes work well as they do not suck in under-bonnet heat. Short ram intakes benfit from heatshields or cold-air ducting.
The aforementioned intakes can seem to reduce throttle response. Using a sealed cold airbox gives you excellent throttle response and more power. You won't get more than 10 bhp with a CAI/airbox if you're lucky.
The K20A2 exhaust is quite good, and replacing it won't help power much at all. You will need a larger diameter if you plan to tune it further though. 2.25 to 2.5 maximum unless you want to use forced induction... Good for about 5 bhp
The manifold and cat are very restrictive. However a decat pipe won't help that much. You need a proper longtube manifold which replaces the cat. The UK car must meet stricter emissions laws for 2005, and loses power as a result. Using a manifold will make from 10-15 bhp.
An ECU retune is probably required after the manifold to account for increased scavenging. All in (intake/manifld/exhaust/ecu) will leave with about 220-225 bhp max.
Uprated cams which feature higherlift and duration will help a lot from here on. Jap J20A cams will increase bhp (with ecu retunes) to about 235-240 bhp. TODA spec A improve on the K20A cams to 250 bhp and have better torque from low-mid revs. Cat Cams 902 have even better low down- but lose about 5-10 bhp compared to TODA As. TODA cams also require stronger valvesprings to allow a safe 9000 rpm re limit.
You can then help breathing a little more by adding a jap intake manifold and a larger throttle body. Makes a small difference and increases high rpm efficiency.
Getting over 265 bhp on a stock head in naturally aspirated form is going to be difficult. None produces cams at present which take advantage of cyl head work. Besides, there is no more room on the piston to accommodate bigger cams. From here its expensive forged pistons and the like...
That's 221 bhp per ton on a CTR
THe mods also increase torque by about 20%. Coupled with CTRs short gearing and light weight, makes this a very rapid car. Addition of a lightweight flywheel helps a lot too.