Friday, August 21, 2009

Breathing Hard & Deep

A Honda Accord with a H22A swap gets a homemade independent throttle body upgrade from Avantgarde!

An internal combustion engine works on the principle that the more air and fuel that it can pass through its internals, the more power it will make. This is why turbochargers and supercharger are such great power adders, because they work on the principle of forcing more air into the engine. For naturally aspirated engines, the amount of power made is highly dependent on how much air and fuel the engine can ingest by itself without the help of forced induction. This is why most high powered, naturally aspirated engines need to rev high to make power, simply because that a lot more air and fuel is passed through the engine's innards at 12,000rpm than at 6,000rpm.

This SM4 Honda Accord has a H22A swap, and the engine is relatively untouched, save for the JUN cams in the head. The owner wanted more power, but he didn't want to touch the bottom end just yet. The exhaust was sorted with an FGK extractor and a full exhaust system so the only thing left to do was to sort out the inlet side of things with an all out independent throttle body setup.

Avantgarde were given instructions to keep costs down, so getting a brand new throttle body set from TWM or Toda were out of the question. The only option; to go for the throttle bodies from Toyota 20-valve 4A-GE. Although the throttle bodies are only 45mm in diameter, compared to Toda's or TWM's throttle bodies which have a 52-54mm diameter, these independent throttle bodies are still better than the stock intake manifold.

Independent throttle bodies are more favourable because they allow a more direct path for air to enter the combustion chambers. The downside to this is that they can be notoriously difficult to tune, which is why Avantgarde chose a Hondata S300 EMS to handle the task. The Hondata is the best ECU/EMS that a Honda engine can get as it is feature packed and can handle anything that the engine needs.

Once the throttle bodies were on, James of Avantgarde had to get the car to idle and run properly before we could get the car on the dyno for some serious tuning. Tuning an independent throttle body setup is a lot of work and much harder than a single intake manifold and throttle body setup because there are so many more variable to be taken into account, because one or two of the cylinders maybe sucking in more air than the others which would require more fuel in it and so on.

The car was strapped on the dyno and we got a baseline power figure of 180.72bhp and 19.87kg/m of torque at the wheels. After an hour or so of trying out different maps and fine tuning said maps on the Hondata, James was finally satisfied with the result, but wanted to see if we could squeeze anymore power out of the H22A by adjusting the cam pulleys. We couldn't get much more power out of it, so we called it a day with 196.17bhp and 21.73kg/m of torque.

On the way back from the dyno, the car pulled much harder and the exhaust note was noticeably edgier. 16bhp isn't a large increase in power but the overall feel of the car was much better. I hope those high compression pistons make it in the car soon.

Custom fitted 4A-GE ITBs
Hondata S300

Before 180.72bhp
After 196.17bhp
Gain +15.45bhp

Before 19.87kg/m
After 21.73kg/m
Gain +1.86kg/m

DTS: 03-6276 6560
Avantgarde: Eric 017-334 1223, James 019-2828 640

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