I'm going to assemble a new 3.5L engine. I currently have a J32A2.

From what I remember, I could swap a 3.5 crank and rods from a J35A3 to make a 3.5L with the highest flow.

Is this currently still the best setup for a 3.5L? I want to turbo after this, so I don't want to go 3.7L.

Any advice would be great!

 

significantly easier to find an existing J35A3 and swapping the heads from the J32A2 onto it, unless you are planning to rebuild the engine with new parts.

 

if the ultimate goal is turbo, drop the compression.

so, whatever you're thinking, do the opposite. LOL

 

+1. J35 type S.

 

I hate to bring up such a divided discussion, but are there not concerns with the J35A3 piston's compatibility with the 36mm J32A2 intake valve? I know people have installed them, turned them on an engine stand and "discovered" no issues. But this does not account for the added lift of the valve being acted upon by the VTEC profile of the camshaft. A few have much more experience with this combination than I do, but I just thought I'd put it out there as something else the OP might want to consider when building an engine.

Anyway, yungone501 has done some pretty cool research into a lot of the more recent J-series piston offerings. Some of the newer dome profiles, coatings and ringland construction would be better suited to a boosted application than old J32A2 or J35A3 pistons while still maintaining a relatively high compression ratio. The thought that lower compression is necessary in a boosted application is fairly archaic. Of course it widens the margin for error, but tuning has become so advanced now that we're able to tweak things more intelligently and don't need the large safety net. This allows the engines we build to maintain decent out-of-boost power as well in the lower RPM ranges. Tony_the _Tiger's TL is a great example of this.

https://acurazine.com/forums/perform...00-whp-901774/

 

Keep in mind there are many ppl running turbo j32a2 ' s without issues up to 700hp.

Every single newer J series turbo build I have seen has reliability issues.

 

Two things to point out so far:

1- The J32A2 valves will NOT clear the J35A3 pistons.

2- (Not sure) I think the J32A2 block is stronger than the J35A3 block (according to Fatty a long time ago)

If both of these points are true, then I think it's best to just swap out the crank and rods from the bottom end, right?

 

People have put J32A2 heads on the J35A3 block without issues. I think it would be easiest to just get a J35A3 engine and swap in J32A2 pistons along with the few other 6speed parts necessary. I think fast times put different cams in his J37 that were even more aggressive.

 

Yea but if I have to change the pistons, I might as well pick the stronger block (J32A2). Also, I'm keeping the engine auto, since I have an AEM EMS 2.

Haven't looked into the J37 cams, but I'm not sure if it would be helpful for a J35 build.

 

you don't have to change pistons. If you have the manual trans, you need certain things from the CL6 engine to swap over to the J35A3 engine for it to run. See tehCL's thread.
If you want a reliable easy swap, then throw in the full J35A3 with the J32A2 cams you already have. Easy, done.

 

But he is saying that you DO have to swap the pistons. I've heard both, but I don't think any argument is more conclusive than the other without proof.

He's also saying that he has an AEM EMS 2, which is designed around the sensors of an engine that was originally equipped with an automatic transmission. Therefore, he doesn't have to transfer sensors.

Karanx7, why would you think there would not be benefits from the J37 camshafts? Which ones, specifically, are you referring to? Or are you making the argument that the cost/benefit analysis makes them not worth it?

 

From what I've read you don't. I'm also saying there's no point in breaking down the J35A3. Use the whole thing, no need to swap heads, pistons. Just put in J32A2 cams which are more aggressive than the J35A3 ones. The differences in the heads for these two motors is minimal. Unless you're going for an all out build, don't over complicate it. If you're going to the point of swapping pistons, then build a J36.
I just looked up fsttyms thread and he is using 3.7 cams which are even more aggressive and hollow (lighter).


https://acurazine.com/forums/frequen...-714305/page5/

 

But like I said in my first reply, that does not account for the higher lift of the VTEC cam lobes. The added lift is what I fear that people are not accounting for. Any camshafts more aggressive than the J32A2 cams would seem to only exacerbate the issue, if there were one.

 

So it seems you CAN use J32A2 heads, and bolt them directly onto a J35A3 without problems.

I have heard that the J32A2 intake valves will hit the J35A3 pistons, but apparently this is a myth.

If this is true, I may just swap heads. The J35A3 pistons will give 10.1 compression (compared to the 10.5 of the CL-S/TL-S pistons).

 

I see what you mean. I guess there's one way to find out.

what about just decking the J35A3 head for the compression bump?

 

What's the hype with swapping the heads? IMO its not worth the hassle of tearing 2 motors apart for 1mm bigger intake valves, not a game changer.

Grab a J35A3, swap the Type S cams over and have a great time shredding tire.

 

If I'm only swapping the heads, I don't have to tear the engine apart. Just a head gasket kit and some head bolts.

I figure I've got the heads already and the engines will be out of the car anyways, would only take an hour max.

Sigh... unfortunately you are right. I'll try to get some more advice from experts, but I'm hoping I won't be the first to find out.

 

How hard would it be to remove the cams? I mean after removing the timing cover, just remove the bolt holding the sprocket, then pull the cams out? Or is there something else involved? I'm assuming it would also need to be on TDC when doing this?

 

It's not difficult to change the cams. However you still have to open the valve covers, and remove the rockers to expose the cams. You cant just pull it out from the side.

I've actually decided to just swap the cams over, so I don't have to mess with the head gasket. I'm losing 1mm intake valve diameter by not using the J32A2 heads, but at least I won't have to worry about valve clearance during VTEC.

 

Thanks. do you already have the engine or are you still looking for one? Definitely let us know how it goes.

 

Just finished swapping cams. You actually do pull it out from the sides, but you still have to remove the rocker arm assemblies.

 

That's stupid high compression if he's planning to go turbo soon after.

Drop that shit to 8.5:1 for easier and safer tunability.

 

This isn't the Industrial Revolution anymore. People have been running high-compression (of which 10.5:1 is not) for years now. Back in the FMU days, it was more of an issue. These days, it's very easy to tune for. A wideband to watch AFRs is about the only additional bit of hardware you would need on top of a good EMS.

 

You can pretty safely run 10.5:1 compression with boost if you have a good tune. Obviously I would prefer less compression, but I would have to get some custom work done for that.

EMS requires a wideband sensor to run.

 

One question for you guys.

I now have the stock J35A3 engine with swapped in J32A2 cams. Should I use the J35 spark plugs and coil packs, or should I use the J32A2 spark plugs and coil packs?

 

"EMS" in this instance being the initialism for any general "engine management system" and not AEM's product marketed under that name.

 

what I've noticed is a lot of people give advice on something they've NEVER done.
drop the 3.5motor inn use IR plugs. (you need colder plugs when boosted ik22 or 24) and you'll wont regret it (more HP/TQ) the 3.5 has lower compression anyway swapping cams is ok but you wont see a big difference.
the engine blocks are the same only difference is crank rods and piston compression.
max bore manifold and runners for maximum air (Hondas love to BREATHE) so no baby primary exhaust piping.
I've been running a 3.5 and 3.7 boosted daily since late 2006 would never go back to a 3.2 motor and still running down 20-30psi evos/sti with ease and full interior

 

Nice info, thanks a lot! Going to stay 3.5 NA for now. I'll build a 3.6L with stronger internals for higher boost down the road. I still need to learn how to rebuild the engine internals.

I think the cams should make a big difference for HP over torque, as the MDX should be tuned for low end torque I imagine.

Did you use the J35A3 spark plugs, or the J32A2 spark plugs? I'm going with the OEM CL-S6 NGK laser iridium plugs for now, unless I learn there's a better plug.

 

I'm a little late to the party but here you go.

the J32A2 and J35A3 share the same block and heads. The crank rods and pistons are different with the J35A3 having both forged crank and rods and 10:1 compression, the J23A2 only has forged crank. Yes J32A2 heads will work on a J35A3, but the simplest solution is to just mill .020" off the J35A3 heads which raises the compression to 10.5:1 like the J32A2 (it's not that much more work if your going to be replacing the timing belt any ways and if your building a motor than your also going to want to gasket match and port the intake track). There are a few little thing that are different between the two like the EGR, MAP sensor body(the plugs are the same), IM horns, the spacer between the upper and lower intake, and the pressure valve and spring in the oil pump. If you want to boost later don't mill the heads and if need be use a thicker head gasket to drop compression further when the time comes.

I'm a little over 50K on my J35A3 with milled and ported heads and now FI . Its not to hard to produce HP in the high 200's with a stock J35A3 short block, some head milling (J35A3 heads), PnP, header, CAI, exhaust. Plus the 3.5 makes about 20% more torque every where.

 

For a street NA application that does not require forged pistons, the J32A2 pistons combined with the longer stroke of the J35 crankshaft (93mm vs 86mm) create an even higher compression ratio than 10.5:1. With the combustion chamber volume being around 53cc, that would yield a compression ratio of around 11.3:1. Even higher if the J32A3 pistons were used, but those appear to be of inferior construction to the J32A2 pistons. I can't back that claim up with anything other than the eye test, though.