Honda J30A Engine Specification & Changes

[hughezee]

For those interested, In 1997, J30A engine was launched with the displacement of 3 litres. This is a typical 60° V6 engine with a compact aluminium cylinder block, its bore spacing is 98 mm, and the deck height is 235 mm. Inside this block, there is has a crankshaft with the stroke of 86 mm, 162 mm connecting rods and 30 mm compression height of the pistons. This provides the displacement of 3 litres and the cylinder block is covered with two 12-valve SOHC heads. These heads use 34 mm intake valves, and 29 mm exhaust valves. The J30A is also equipped with a variable valve timing and lift electronic control system VTEC. The camshafts are rotated by a timing belt to be replaced after every 60,000 miles. Don’t underestimate it, since if the belt breaks the valves will be bent.

In addition, you should adjust valves after every 25,000-30,000 miles. Here are the valve clearances for a cold engine: 0.2-0.24 mm for intake valves, 0.28-0.32 mm for exhaust valves. The J30A engine uses 240 cc/min fuel injectors. The diameter of the throttle body is 60mm and the firing order is 1-4-2-5-3-6. Based on the J30A engine, a while family of J engines was developed: J25, J32, J35 and J37.

This 3-litre engine was manufactured until 2007, and then it was replaced by the popular J35. Today, you can buy an Acura RDX in China, and it will be fitted with a J30Y engine. This is the only version that has not yet been discontinued.

J30A engine modifications and differences

• 1. J30A1 is the first modification of the engine, here the VTEC is activated after 3,500 rpm. The power was 200 HP @ 5,500 rpm, the torque was 264 Nm @ 4,500 rpm.
• 2. J30A4 – this engine uses new pistons (compression ratio 10), the intake valves diameter was increased to 35 mm while the exhaust valves were not changed and remained 30 mm. There was also a modified VTEC system, a new intake manifold, an electronic throttle body, and a new exhaust manifold and exhaust system were installed. These mods were successful, and the power increased to 240 HP @ 6,250 rpm, and the torque to 286 Nm @ 5,000 rpm.
• 3. J30A5 was the analogue to J30A4, its power was 244 HP @ 6,250 rpm, the torque was 286 Nm @ 5,000 rpm.
• 4. J30Y1 was a modification for the Chinese market. It was installed in Acura RDX.
• 5. JNA1 was a version with an electric motor made for Honda Accord Hybrid. This engine reached 255 HP @ 6,000 rpm, the torque was 315 Nm @ 5,000 rpm.

[DeanoCoupe]

Excellent write up! How does one adjust the valves?

[hughezee]

Probably not recommended for the average DIYer, but if you're handy with a 10mm spanner and a flat end screwdriver its relatively straightforward job but it is time-consuming as the engine will need multiple rotations just for one cylinder to get it bang on with a good quality set of feeler gauges.

Additionally, it strongly recommended to replace all the valve covers oil seals and at the very least the intake gasket and there is a special tool to make the job easier, well getting the tight with the correct clearances anyway. 👍

Hope that's enough info, if not I have linked a couple of videos of below...

 

[DeanoCoupe]

Nice one Stu, I know a man who can 😉 Im novice DIY'er at best, just don't have the patience or confidence to work on my own car 🙈