I recently acquired a J35Y6 short block, so now I'm looking for heads to put on it. I had originally been planning to build a K24 engine, but want to try to use the J35 now that I've got it. I do plan on using a turbo, but want to keep the build relatively mild so I can still keep a high reliability for long road trips. I'm imagining 400-500 horsepower, which should be more than enough to really enjoy this car. I had been planning on using a 4Piston Racing head on a K24, but now I'm not sure what the best option is for the J35. Any ideas for the best heads for my application?

 

Thats interesting I’ve kind of been on that same thought process of being between a J series and a K24, since the K24 has so much more of a parts availability, I’m wondering what car this will be going in? That could make the difference of whether it’s worth it to go K24 or J series.
As for J series cylinder heads, I’m not aware of any being really more performance oriented than others, although maybe the Acura TL ones have the most stock HP, but I’m pretty sure as long as you get cylinder heads that fit and are compatible with your 3.5 liter block, they should/will support your goal of 400-500HP. Since you’ll have so much displacement and a turbo (or two), the cylinder head won’t really be a limiting part/bottleneck. If a 1.6 liter D series stock port cylinder head will support 400HP while turbocharged, then you should have no issue with which ever J series heads you use, as long as they are compatible with your block. As for compatibility, I’m not exactly sure if all J series heads are interchangeable, it’s something I haven’t researched. Also, pick cylinder heads with parts available if possible.


J series cylinder head parts
As you can see from Supertech Performance’s catalog, they do make some parts for the J series, but not very much. I don’t even see valve stem seals from them.
So if staying J series, you’ll be fine with whichever cylinder heads are compatible, but it might be worth it to go K24 since as you were saying there is the 4Piston K24 cylinder head available and so much more.
Which ever route you take, I’d be interested if you posted your set up once you figure it out.

 

The car is a 1992 Civic hatchback. It certainly does not “need” a high power engine- and honestly even 400 hp seems pretty high power for the car. I may even look at adding some tube reinforcements to really stiffen it up and give good mounting locations for everything. I want to keep the interior as non-racecar as possible though, and I plan to add sound insulation and nicer seats and whatnot, this car will be built for cross-country road trips with some fun spirited driving when the opportunity comes up. The better torque from a J-series is just really appealing, and I think even a mild build on this thing would feel fantastic. Whatever I end up deciding, which at this point could still end up being a K-series, I’ll be sure to post everything I can.

 

The advantages of the K series are: easier swap, more parts available, more space in the engine bay, easier to find a transmission.
Advantages if J series are: more torque at low RPM, less modifications/ boost required for 400HP, unique appeal rather than typical K swap.

So I’d say either one is good for your goals. Hopefully someone other people have info to add. If you haven’t already see this video it’s good tech info:
https://m.youtube.com/watch?v=vYZQYFcxzxo