AP2 Engine In An AP1 Chassis? It’s Worth Considering.

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If your AP1’s F20C engine has some internals show up in the oil filter, an AP2 engine might not be a bad replacement.

Zygrene is a prolific user of his S2000, and of the S2KI forums, so you’re probably already familiar with his track and mechanical knowledge of our favorite machines. But, recently, a money shift had caused him some trouble when he was at Buttonwillow Raceway Park and shifted from 3rd to “4th” via 2nd gear. Despite early indications that compression and the cylinder head were mostly fine, an oil change with copper particles revealed that parts of the inside of the engine weren’t so happy with the over-rev.

Although an original engine was considered at first, an AP2 being parted out revealed a unique opportunity: swap in an F22C AP2 engine instead.

AP2 Engine F22C AP1 swap

Obviously, not everything about a swap like this is straight forward, especially if you’re only swapping over the long-block. This means the AP2 engine could over-rev, because it’s still running on the AP1 ECU, but it is pointed out that the piston speed wouldn’t be much greater. As well, it’s still hooked up to the AP1 transmission as well, which is geared for 1000 more revs.

Could it be that the lower revs and gearing make for a brief moment that the car isn’t within VTEC? In some quick street testing, it looks like that’s not the case, thankfully. It still engages at 6000 RPM, but the drops in RPM between shifts are ample enough to keep it on the power-band.

Despite the F22C that was swapped being a higher mileage engine, it still was mechanically sound. Track driving hasn’t occurred yet, but initial street impressions reveal a meaty torque curve due to the higher displacement. Will this translate into quicker lap times? It very well could.

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