JarrettLauderdale

This information has been perpetuated often enough that I foolishly took it as fact. People often say that J35A3 heads are the same as J32A2 heads. They're not. They're the same as the "base" heads on the J32A1. I'm usually excellent about checking part numbers and cross-referencing information, but I guess I had just heard this enough times that I never thought to fact-check it. Even when I knew the intake valve size to be different. But sure enough, they have P8E stamped on them instead of PGE.



Sorry about the rant. I was just pretty bummed today when I tore down the engine. I expected to just swap out the cams and the only concession I was making was the fact that I'd be stuck with the 10.5 compression ratio of the J35A3 pistons instead of the 11+ I'd have if I used the J32A2 pistons.



Anyway, I just bought a J35A3 this week to put in my CLS6 that needed a valve job and has a leaking rear main seal. Instead of doing all of that work, I just bought a new engine (85K miles), clutch (Luk), timing kit (OEM, Aisin and Koyo parts), gaskets and seals (mostly OEM Honda) and spark plugs (NGK) to install as a refreshed upgrade.

gnuts

iTrader: (1)

I always heard the J35A3 had smaller head ports but only by like 1mm. Can you take any measurements? It would be nice to clear it up and have exact number differences.
Also can you deck the heads to bring compression back up?

JarrettLauderdale

I'll measure them, but the castings are the same as the J32A1, so whatever specs we have on those should be applicable here.

I'm not going to bother decking the heads for this application. I looked for a low-mileage engine because I wanted to avoid a rebuild. If I'm pulling the heads and replacing headgaskets, I might as well swap the J32A2 heads on instead. But that wouldn't do anything to bump compression, which wasn't my concern with the heads being different in the first place.

It could be that the only difference between the heads is valve size and that the intake runners have the same volume as J32A2. I guess we'll have a clue when I take a dial caliper to the runner openings.

teh CL

iTrader: (1)

Interested in the specs..

End of the day though, you won't be disappointed

Karanx7

iTrader: (2)

Correct, the intake valves are 1mm smaller. The exhaust valves are the exact same size.

JarrettLauderdale

Alright, so a slight change of plans. After doing a bit more research with part numbers I've decided to ditch the J35A3 heads. I probably would have been okay with the heads if it were not for two additional things.

First, the valve springs are the same part number as the J32A1 so adding the J32A2 camshafts to them, while already done successfully by others, would have me less than confident about their ability to hold at higher rpms. Using the J32A2 valve springs just makes me feel a little more comfortable.

Second, since this engine was only produced in 2001 and 2002, it uses the old lost motion assemblies in the valve train. The 2003 engines used an updated design that even the lower-end engines received. As my J32A2 is from a 2003 CLS6, it will utilize the revised LMAs.

So, since I'm taking the heads off anyway, it only made sense to buy new pistons to install. I went with some J32A3 pistons to increase the compression ratio to a stupid amount. I will test the pistons against the piston-to-valve contact theory before I reinstall them. I'll see if I can figure out how to lock the VTEC rocker to fully actuate the valve. I imagine that some people are determining the compatibility of the 36mm intake valves with pistons designed for 35s by installing them and turning the engine. If VTEC is not engaged, the valve isn't coming down far enough to give you good information. So I'll see what information that yields and report back.

JarrettLauderdale

Yet another component of the J35A3 I've found that is different to the J32A2 is the oil pump. Only this time it's only the 2003 6-speed 3.2CL that has the different part number. All other J32A2s, J32A1s and the MDX J35A3 share a part number.

I'm buying a 6-speed J32A2 tomorrow so that I can have some downtime to rebuild the heads and possibly port the exhaust sides. When I tear it down, I'll check the oil pump to see if I can tell what the differences are. I don't recall seeing the oil pump mentioned as something that needs to be swapped when converting an automatic engine to a 6-speed, so I'm curious as to what it could be.

Any thoughts?

Edit* Never mind. There is a difference. But it's only in the presence of a bolt hole. I looked on Teh CL's swap and he just put the 6-speed sensor on the P8E oil pump and left one part of the holder bracket unbolted. Oh well.

teh CL

iTrader: (1)

Ya that extra bolt hole is the only difference

JarrettLauderdale

It's my turn to eat crow. My initial purpose for making this thread was to say that people had been spreading misinformation. While the J35A3 and J32A2 heads do not share the same part numbers and have different sized intake valves, they are the same castings. The castings for the MDX heads are P8E, and so are the J32A2 heads. So are the J32A1 heads, J35A4 heads, and I'd be willing to bet the J35A1 heads, too.

I was very surprised to tear apart the J32A2 that I bought only to discover that it had P8E stamped on the heads. I took off the heads and measured 36mm for the valves as opposed to the 35mm intake valves on the J35A3 heads.

However, I still gained the updated LMAs, valve springs and camshafts by buying the J32A2 for parts.

By the way, I have teardown, parts cleaning and reassembly pictures that I'll post soon. I'll wait until everything gets buttoned back up before putting them on here. Then we'll have to see if the factory ECU can support 11.8:1 compression with an additional .3L of displacement.

Karanx7

iTrader: (2)

Definitely post pictures, you're doing some awesome work! The only thing you should regret is taking off the heads. From what I understand, you could have swapped out the valve springs, camshafts, and the LMAs without removing the heads from the block. Now you have to get a new head gasket and prep the surfaces again.

Still, you would have to do that if you're gonna swap pistons.

JarrettLauderdale

Yeah, this is a complete rebuild with everything but the crankshaft coming out. All four deck surfaces are true, so I'm not concerned about that. New rod bearings will arrive tonight to put in the rods along with some that I already had. I still need to get a J32A2 head bolted down to see if it will clear the J32A3 piston. If those valves will clear that piston, they will clear any OEM piston.

DrewsQX56

Any updates or pictures to this thread? I am interested in any 3.2 to 3.5 info I can get my eyes on.

JarrettLauderdale

I have a lot of measurements I'm compiling, and I still haven't finished the rebuild. It became a full on rebuild not very long into it and I've just torn down the heads. I expect to have it finished in a couple of weeks just working on it in my spare time.

Karanx7

iTrader: (2)

Are you going to hone the cylinders? I've heard from some that you should, while others say it can cause blow-by.

JarrettLauderdale

Not on this engine. The cylinders looked very good with no ridge at the top. I used my dial bore gauge to check 6 points in each cylinder, and everything was well within spec. I searched for one with low miles, so I'll attribute the absence of "out-of-roundness" to that.

Honestly, if this engine can last me 20,000 miles, I'll be happy. I have a few more engines and I'm going to start a slow turbo build soon. The thing about these engines is that people are putting them in everything. If it happens that I abandon that project, I can still use it for something else.

WHEEELMAN

iTrader: (14)

Curious if those J32A3 pistons cleared the valves...


and will be really curious to see how that OEM ECU handles the comp ratio under full throttle w/o any tuning solution.








Also, I'm sure you found out the block casting for the J32A2 and J35A3 do have slight differences.

JarrettLauderdale

I haven't rebuilt the heads yet. I've had many other projects that I've been trying to get done that takes up the garage space needed. I've lapped the valves, but then let everything get out of order. Some work is in order for this weekend, though I doubt I'll have them fully rebuilt by tomorrow night.

I'm looking forward to seeing how they do with the OEM ECU as well. After two attempts I was still not able to get reliable data when measuring dome volumes inside the cylinder. I can see that the dome volume of the RDA piston is greater than that of the PGE piston, but not by an intense amount. If the J32A2 piston dome is around 2-2.5cc, then this one is about 3.5cc, or so. The plan is for this car to eventually be run on AEM Infinity 6, but some of the Civic guys have put quite a bit of power through the OEM ECU. I'll just have to wait, I guess.

And you're going to have to help me out on the blocks. At first glance they certainly look the same. Aside from the stamp, of course. Acura even lists them as the same part number.

Karanx7

iTrader: (2)

The blocks are identical 100%. I previously thought they were slightly different, but they are the same exact part (except the stamp like you said).

signalpuke

Anyone have an actual list of what is different between the J32/35 motor?

I mean the whole long block (head/block/rotating assembly) which shares the same casting (bolts up to the same family of transmissions).



I have been looking for a complete J32A2 or J35A3 (If those are the same block casting) but with so much misinformation in these threads...

These are the same blocks and heads. Just different rotating assembly, correct?
J32A2 (2001-03 Acura CL and 2002-03 Acura TL)
J35A3 (2001-02 Acura MDX)

JarrettLauderdale

Yes, they're the exact same block. Much of the misinformation comes from people who spout of things with no basis at all, or basis in some logic that makes no sense. Part number comparisons and real-world analysis just aren't relateable concepts for some people. I'm not free of criticism myself. I began this thread seeking to refute something that had been widely spread as fact. While I did help to clear some of the confusion up, I did so by speaking before I had all of my information straight.

The J35A3 pistons have a lower dome volume which will cause a lower compression ratio.

The J35A3 rods are slightly shorter to accommodate the longer stroke.

The J35A3 crankshaft has a longer stroke.

Other than those, the J35A3 short block uses the same part numbers as the automatic J32A2. The 6-speed J32A2 uses an oil pump with an additional threaded mounting boss for one of the MT-specific crankshaft position sensors.

signalpuke

Thanks. I assume the engine wiring harnesses are also similar, if not the same. This is correct? (not bothered by the charge harness, only crank/cam etc sensors on the engine)




On to the heads... I understand a lot of the heads are 'interchangeable' among all of the J-series family. They all can bolt on, but not all can actually be used without modification.

What heads bolt on to which blocks? Which require mods?


And the intake manifolds are all pretty much the same bolt pattern, that is, they can be used on almost any set of heads from the J-series family?

03 tls nc

iTrader: (6)

Both blocks are the same. The only difference in the oil pumps is the pressure valve and spring, the J32A2 parts can be purchased for around $20. The coolant crossover manifold is different but can be made to work. The EGR valves are different and must correspond to the appropriate ECU. Of course the crank, rods and pistons are different. J35A3 has forged crank and rods but they are not comparable to after market forged rods but still better than cast (J32A2 has forged crank only). The heads are the same castings and use the same valve seats even thought the J32 uses a 1mm larger intake vale (with a valve job the smaller valve will flow more, due to less shrouding). Lost motion assemblies were updated for the 03 J32. The cams and springs are different (J32 springs are considerably stronger). The intake of the J35 utilizes are 1" spacer between the upper and lower runners and the upper intake is the same between the two with the exception of the longer trumpets used on the J35 (produces more torque below peak). The TBs are the same with the exception of the MAP sensors and the corresponding MAP sensor must be used with the correct TB (both use the same plug).

If forced induction is in your future use the J35A3. Clean up the casting marks in the intake tract but do not increase the size and enjoy the lower static compression and cams with less over lap. (upgrade the oil pressure spring and valve for good measure)

For some NA fun on the cheap start with J35A3 use J32A2 cams and springs, port from the J35A3 IM to the valves, valve job and mill the head. (.010" is approximately equal to 0.25:1 static compression with J35 rotating assembly). I milled mine to 0.030" with no valve clearance issues and an estimated 10.75:1 static compression (no issues achieving correct mechanical timing with 0.030" milled). I also upgraded the oil pressure spring and valve in the bottom of the oil pump.

Assuming that even if you don't separate the heads and run the long block as is replacing all exterior seals and gaskets only makes good since. Since you have to pull the pan to replace the the gaskets behind the oil pump and pickup, removing one allen plug and dropping the J32A2 oil pressure spring and valve in place is some really cheap insurance.

signalpuke

As always, links to reference material are always appreciated. Not that I don't trust everyone here, but it gives me more people to ask specific questions of.

Thanks for the info. I am not concerned with the ECU things, going stand alone.
Motor is going into an NA2, so I should have a bit more room to work with things that are attached to the motor (boost options). Yes, going DBW, so ZDX TB will be used and J37 magnesium manifold.

Just looking for motor specific things regarding compatibility. Boost (supercharger) is my plan, so the best OEM starting place is what I am looking at, then go from there. Best OEM rods specifically. Probably use 410cc RDX injectors for now anyways, so not too crazy, less than 15lbs of boost.

Not too worried about cams, I will go custom when the time comes, unless there is a legit (documented) reason to go with something OEM. I will be upgrading valve springs regardless due to RPM protection (possible misshift) and boost (keep the valves closed under intake pressure).

Now... does anyone make some nice headers? Or should I just have some made? Thinking this is the best option, especially given the engine swap/chassis being used. Recommendations are always appreciated though.

EDIT: I don't want to deck/mill the block. Too many things to take into consideration regarding timing/clearances that I would rather just buy pistons to accomplish.
Great info on the forged internals though. I want more of that. What is forged?

teh CL

iTrader: (1)

JarrettLauderdale

I can't find anything to support the claim that the J32A2 oil pump has a stronger spring in it. The part numbers for the springs are the exact same between the J32A2 and J35A3.

JarrettLauderdale

After looking around a little more, I found that nearly all J-series engines from '97-'06 used the same oil pressure spring and valve that the J32A2 uses. The difference I found is not until '07 with the TL Type-S J35A8. Even the J35A8 in the '05 RL uses the same one as the J32A2. Luckily, both parts are dirt cheap and will run you about $10.

SykVSyx

OEM part #'s?

signalpuke

Soon. I'll make a 'build thread' for it. I am still trying to figure this J-stuff out lol. Car needs to go to paint after the motor is pulled anyway.

How do these motors handle the M90? The J35A3 and the J32A2, which has the better OEM rods, and does anyone know when they start to get bendy?

Tuning can assist, but I want to at least start with the better bottom end before I blow the motor up :P

The oil pans are the same correct? Anyone make a baffle for them? If not, no biggie, I'll have one made.

SykVSyx

Either engine can handle the M90 S/C, it's when you start getting in to the J37 build, that there may be issues with boost, because you are reaching the limits of the bored block.

03 tls nc

iTrader: (6)

I linked two pages below, parts 6 and 7, they are different I compared both side by side on the bench.

OIL PUMP - OIL STRAINER (1) for 2002 Acura MDX

OIL PUMP - OIL STRAINER for 2003 Acura TL

JarrettLauderdale

That's odd. The '03 CL-S6 doesn't seem to benefit from that part number according to the parts diagram, but the automatic cars do.

03 tls nc

iTrader: (6)

That is funny, its been a while since I researched and found the difference between the oil pump springs and valves but it seemed like any engine with 6900 rpm redline received the upgraded components. I remember reading on one of Paul's (NVAV6) build posts where he was cutting washes down to place under the spring to raise oil pressure on his J30 builds when stroking them and increasing redline. Why reinvent the wheel since a team of Honda engineers have already figured this out for us.

SykVSyx

https://acurazine.com/forums/3g-tl-p...-908987/page3/

Post #109/110 should clear things up.

hitek9

Do you have to mill the block? I am planning a j35 and 6 speed swap at the same time, so I want to make this as easy as possible. You guys have enlightened me to use the j32 cams, springs, and lmas. i would have to use j32 egr and throttle body as well? Use the '02 auto j32 oil pump spring? What else should I order?

I hope to get this done over the weekend. I work at trans shop, so I'm used to removing and replacing engines and trannies, but not with a different motor or auto-to-manual swap. It will be a learning experience.

03 tls nc

iTrader: (6)

I did not mill the block. If you separate the heads make sure to check the block for flatness. You should use new head bolts or studs. It is a perfect time to port the intake tract and have a valve job done while you have the heads off. If you plan to add FI in the future I would not recommend milling the heads. Make sure you do a leak down test before you tear down, it can safe you some heartache later. It is also the perfect time to drop in an ASCCO flywheel and better clutch along the with clutch mods. Please save yourself the trouble and use Honda gaskets!! Have fun and enjoy the ride!

hitek9

I'm on budget and time constraint, and I'm pretty much doing this by myself, so I will not take apart the heads if I don't have to. The j35 I ordered supposedly has 80k miles, I'll be sure to do leak down test first thing. Also ordered luk clutch kit, and plan to take flywheel to local machine shop if it's saveable.

Didn't mean to take over this thread, just trying get as much info as possible. I searched and didn't find any build threads

03 tls nc

iTrader: (6)

hitek9 I would suggest replacing the flywheel, they are dual mass and the rubber connecting the two plates will give issues. Honda recommends replacing the clutch and flywheel together.

hitek9

I'm being cheap as fuck right now, only buying what I need. Took it to machine shop this morning, they said it was saveable, I have to go pick it up now. Anyone know what to do about obd2 port? The trans ecm is all I need also, right? Do I need the brake pedal as well?

Thanks guys

hitek9

OK I snaked that harness out. Do I need the block it plugs into? Alot of other stuff plugged in there. Don't want to take it out if I don't need it. I can't wait to be done with this project

Karanx7

iTrader: (2)

Dude, make your own thread and I can help you. I've converted from Auto J32 to Manual J35 myself.