The J35A1 Cylinder Head: Specs, P8F Casting & Build Guide
The J35A1 is one of the lowest-output members of the Honda & Acura J-series V6 family. It's a 3.5L SOHC VTEC V6 built around the smallest ports and valves of any J-series head, plus an unusual two-lobe VTEC system you won't find on the later motors. On paper those small ports look like a handicap. Built the right way, they're the key to a strong, linear power curve. Here's what sets the J35A1 head apart, how to spot one, and how we wake it up without throwing away what makes it good.
J35A1 Quick Specs
| Engine family | Honda J-series V6 |
|---|---|
| Displacement | 3.5 L (3,471 cc) |
| Valvetrain | SOHC 24-valve, VTEC |
| Head casting ID | P8F |
| VTEC design | Two-lobe / two-rocker (intake side) |
| Factory lost-motion springs | None — empty pockets in the casting |
| Intake valve | 34 mm |
| Exhaust valve | 29 mm |
| Intake port vs. J32A2 | Roughly 30% smaller |
| Vehicle applications | 1999–2001 Honda Odyssey |
| Factory output | ~210 hp |
How to Identify a J35A1 Head (P8F Casting)
Honda casts an identifier into every J-series head, and the J35A1's is P8F — that casting mark is how you tell it apart from the newer castings at a glance. If you're not sure which J-series you're working with in the first place, start with our J-series engine-code finder.
The Unusual Two-Lobe VTEC
Most J-series heads use a three-lobe VTEC rocker setup. The J35A1 is different: the intake side runs only two lobes and two rockers, and one of those lobes is tiny — very little lift and duration when you're out of VTEC.
The good thing is, even though this cylinder head doesn’t use LMA springs from the factory, the pockets are still cast into the heads. So when you convert over to the 3-lobe VTEC, you simply grab a set of LMA springs and drop them right in.
Why the Small Ports Are a Hidden Advantage
The J35A1's intake port is about 30% smaller than a J32A2 or any of the newer J-series heads, and its exhaust port is smaller too. The valves are the smallest in the family — a 34 mm intake and a 29 mm exhaust, versus the 30 mm exhaust and 35–36 mm intake you'll find on 2002-and-newer motors (and a 36 mm intake on everything from roughly 2008 up).
A smaller cross-section keeps intake velocity high at low RPM, and high velocity is what makes torque down low. So while the J35A1 head will never flow like a big-port casting up top, it builds a stronger, more linear bottom-end power curve. That's exactly what you want for a horsepower- or displacement-capped race class, a lighter and more responsive street setup, or a low-RPM specialty build — we've used this same small-port approach on an off-road rock-crawler engine whose entire goal was grunt down low, where a big-port head would only have hurt it.
The P2R Recipe: Small Ports, Bigger Cam
Here's how we get the best of both worlds — keep the small-port P8F head for velocity, but give it a real valvetrain:
What goes into it
1. Fill the empty lost-motion pockets with our P2R J-Series VTEC Lost Motion Assembly — they drop straight in.
2. Switch the intake rocker assembly to the three-lobe setup from any of the following J Series Cylinder heads (J32A2, J35A3, J35A4, J32A3, J35A8, J35A6). Once the LMA springs are in, it bolts right in. The factory exhaust rockers stay — they fit perfectly with our cam, so only the intake side changes.
3. Run our P2R Stage 1 Billet Hypercam. It makes more power than a stock J35A8 or J37A1 cam across the entire RPM band — with gains starting as low as 3,000 RPM, not just at peak.
4. Feed it air with our J-Series CNC Ported Lower Intake Manifold Runners, and back the bigger cam with upgraded springs like the Pro Valve Racing Stage 3 valve springs, Ferrea Spring Kit, or Supertech Spring Kit.
The result is a head that still has the J35A1's high-velocity small ports but now breathes and revs closer to the better castings — it still doesn't quite out-breathe a big-port head up top, but it's a genuinely strong, driveable combination.
Case Study: Building a Linear 215 HP
We put this exact approach to work on a customer's engine for a race class with a hard 215-horsepower ceiling. The goal wasn't big numbers — it was the most linear, usable 215 hp possible, so the car is a front-runner everywhere on the track, not just at one RPM.
Full shop walkthrough of this J35A1 head build on our YouTube channel.
The build keeps the small-port P8F heads (with our Hyper Stage 1 cam, LMA springs, and the three-lobe rocker swap) and bolts them to a J35A4 block — the smaller valves mean there are no piston-to-valve clearance worries even with the larger cam. To hold velocity we ran a P80-series CNC-ported lower manifold and the P8E runners from an '02 TL base model (not the larger-port Type-S runners), keeping flow modest on purpose. Decked 0.015" to true them up and well inside Honda's cast service limit, this combination is built to put a strong, flat 215 hp right where the class needs it.
J35A1 FAQ
How much horsepower does a J35A1 make?
In factory trim it's one of the lowest-output J-series engines, around 210 hp. That low baseline is also why it makes such a good foundation for a controlled, low-end-focused build.
What's the difference between a J35A1 and a J35A4 head?
The J35A1 (P8F casting) has noticeably smaller intake and exhaust ports, smaller 34 mm intake / 29 mm exhaust valves, and a two-lobe intake VTEC. The J35A4 heads have larger ports, 35 mm intake / 30 mm valves and the traditional three-lobe VTEC. The J35A1's smaller ports trade peak flow for low-end velocity.
Can you port a J35A1 head to match a bigger casting?
Not practically — the casting doesn't have the material to open the ports up to a larger head's size. The smarter path is to keep the small ports for velocity and upgrade the valvetrain (cam, lost-motion assembly, three-lobe rockers), which is exactly the recipe above.
Is the J35A1 a good engine to build?
For the right goal, yes. If you want a strong, linear low-end — for a capped race class or a responsive street car — its small ports are an advantage. If you're chasing a big top-end peak number, a larger-port J is a better starting point.