Hi Azine, I have a 2005 3GTL 6spd and I just picked up a J37a1 short block for $90! Bada bing!

I've read all of the 3.7L build threads and I'm ready to do my own. I'd like to lay out my plan, have questions answered, and fully document my build in this thread as I make progress.

The build:

J32a3 block, bore to 90mm
J37a1 crank, rods and pistons
J37a4 heads w/ dual vtec
2004-2006 6mt
Hondata tune

My question: Why shouldn't I use a J37 block?

- Will the J37 block mate with my 6MT tranny?
- Would a J37 block fail (california) smog visual inspection?
- Can I keep my 2005 ECU if I use a J37 block?
- Will J37a4 heads bolt onto any J block I choose without issues? I really gotta have dual vtec!

These are my concerns for now. I'd HUGELY appreciate any warnings and tips for people who have already gone down this road. Thanks for all your help azine! Pictures and instructionals coming soon!

 

The biggest reason not to is because you simply can't. The j37a1 block will not bolt up to the 04-06 TL 6MT. The second reason being that the j37 blocks cannot be bored like a standard iron sleeved j-series engine because they are Nikasil coated. This means that once the cylinders have been bored true again, they must also be recoated which is not only expensive but is also hard to find a reputable company that can do the job correctly. Since the blocks have solid aluminum cylinders, the steel piston rings would gall the aluminum very quickly. Nikasil is a very thin coating that provides a hard enough surface for the rings to ride along without damaging the soft aluminum cylinders.

See above.

No.

Only if you were to use a 6MT from an 07-08 TLS and the 07-09 MDX J37a1 block as it still uses the oil pump mounted crankshaft position sensor like the j32a3 & j35a8 use. You could use any other j37's (10-13 MDX, 09-14 TL AWD, 09-13 RL, etc) but not without first converting them by simply swapping the oil pans. From what I've seen, all the latest j37 oil pumps still have the provisions to mount the j32a3 & j35a8 style crank sensors.

Only if the engine they were mounted on a block that originally came with single port exhaust style cylinder heads. Otherwise, it would require some modifications to the block or head to work on older blocks that originally had the multi port exhaust cylinder head such as a j32a2. Dual VTEC sounds badass btw! I currently have these heads on my j35z and love them.

Lastly, these heads DO require increased oil pressure from the oil pump which can be done to any factory oil pump by simply installing a j37a2 or j37a4 relief valve and spring into it. This is because the heads require double the amount of oil to actuate the VTEC system thanks to the addition of the exhaust rocker setup.

I'd highly recommend speaking to a reputable camshaft company (not Gude!) about having custom profiles made for your setup. This will definitely help the setup provide much more power in your setup and will be tailored to your exact needs/expectations. Good luck!

 

Yungone thank you so much for hooking it up with answers and amazing info I haven't found elsewhere.

As I collect information I'll compile all of this info into the original post so that other searchers can hopefully find everything they'd want to know about 3.7L builds.

I've been offered a j35a7 bare block. That's used in the Odyssey 2005+ and I'm wishfully thinking any J35 block would suffice. However the j35a7 has oil channels that support VCM. I don't know if that is managed entirely by the head, or if alterations are made to the block as well. I certainly don't want any wierd VCM action!




Heres the crank and pistons I pulled from the donor J37a1 today. All in good shape. Man is that crank built like a tank!