DIY: 3.2L to 3.5L engine swap (+ Type II Swap, Hybrid, and JDM Information)

Mike Diaz · 11-04-06, 12:13 PM

How to install a 96-04 3.5L Acura RL engine into a 91-95 Acura Legend

Things you need:
96-04 RL block (EDIT: 02-04 RL engines were rated with more horsepower & Torque, but it was related to muffler and ECU changes, not engine design. This will not benefit you with Legend electronics and exhaust.)
RL heads
RL driver side valve cover
RL intake manifold
RL throttle body
RL timing belt covers
RL egr valve
RL passenger side front engine mount. The 96-98 and 99-04 3.5L's have different mounts. Make sure you know which engine you have
RL exhaust manifolds and 02 sensors (optional, but I used them)
RL fuel rails, fuel pressure regulator, and fuel damper (optional, but I used them)
RL timing belt and tensioner
RL balance shaft belt
Legend Coil packs
Legend passenger valve cover & sensor
Legend wiring harness
Legend injectors
Legend alternator
Legend power steering pump
Legend A/C compressor (if equipped)
Legend differential
Legend front driver side engine mount
Legend front passenger engine mount
Legend axles
Any Legend transmission will bolt up to the RL engine. Only one bellhousing bolt will not line up. Ignore that one bolt.

You do not need:
RL differential
RL injectors
RL wiring harness
RL coil packs
RL ECU & ignitor. (Anything that isn't connected to the engine)

Buy an engine stand and mount the RL engine to it. Then strip the engine down to the Block, heads and the driver side valve cover. Yes, the intake manifold should get new gaskets. Get your passenger side, front engine mount cut and welded so that the RL engine mount side bolts to the engine, and the Legend mount side, bolts to the rubber mount (see pictures for 91-93 Legends).

Now is the time to clean and paint your engine if you want. I used High temperature low gloss black paint on the block and heads, and VHT gray wheel paint on the valve covers, intake manifold, and the timing covers, and it turned out good. You can do any color, just make sure it's quality high temp paint. This may also be a good time to change the spark plugs (NGK or Nippon Denso only), timing belt, water pump, balance belt, and tensioner.

Get new intake manifold gaskets and reinstall your intake manifold with new gaskets. Install the LEGEND injectors and the RL fuel rails (optional) on the intake manifold. The intake manifold will have vacuum tubes running off by each injector, cap those off. (I didn't, and those blue tubes that are capped off are the end result. I plan on capping them off at the injector housing when I pull my intake manifold again)

Install the LEGEND differential on the side of the oil pan, then install the LEGEND starter.

Once the engine is bolted to the transmission , you can install the LEGEND coil packs and the LEGEND wiring harness. Here's where it gets tricky. There's a few splices that must be made in the LEGEND wiring harness.

First, on the coolant connector tube that runs between the upper radiator hose and the heads, those two sensors are switched around, you'll need to extend the wires on both of those sensor plugs about 6-8 inches so the wires will reach the opposite side.

The oil pressure sender plug down by the balance shaft will need to be extended about 4-5 inches. Also, on that plug, since the power steering belt is so close to the timing cover, you have to run the wire out and zip tie it to the lower radiator hose and then plug it in (see pics)

The intake air temperature sensor that used to be on the front of the intake, is now on the rear of the intake. You'll have to extend that wire out about 10 inches to reach around the back side of the engine.

Swap the Legend valve cover onto the passenger side of the engine and use the original Legend sensor in the rear of that valve cover.

Go out and buy a small roll of vacuum tube ($10-12) and run your own lines where needed. Most of the original lines will match up. IF YOU GUT YOUR INTAKE MANIFOLD: You won't use a few of the lines if you gut the intake manfold. These unused lines lead up to the vacuum solenoids behind the passenger headlight and will get capped off at the solenoid.

The crank/cam position sensor behind the driver side cam gear has a plug that does not match the Legend wiring harness plug. You have to cut and match up all the wires, solder, then heat shrink the wires. The wires are the same color on each side, so matching them up is easy.
It's time to install the 3.5L engine! You will find that only one of the passenger side bell housing bolts will not bolt up to the 3.5L block. Don't worry, it won't cause a problem, just leave it with no bolt in it. Automatic Transmission: don't forget torque converter bolts - Manual Transmission: Don't forget to reinstall the slave cylinder and clutch fork
Almost done. Next, you're going to take the Legend fuel line that runs from the fuel filter to the engine, and you're going to slowly bend it upwards, so it will match the RL's fuel rail (see pics). Bolt it down to the fuel rail with the fuel damper behind it. Make absolutely sure you don't kink this line. If you decide to use the Legend fuel rail, you will use your Legend fuel line

IF YOU USED THE RL FUEL RAILS: Last thing, on the RL's fuel pressure regulator, the vacuum line running off it is smaller in diameter than the Legend. Buy a vacuum line size reducer and some hose, and use a small hose clamp. Make sure it won't leak.

Double check all your connections, make sure all your bolts are tight. I use Mobil 1 Synthetic 5w-30. Triple check all your connections, make sure all your fluids are full, and cross your fingers. It may take a couple of cranks to start, since your fuel rails will be empty. If it does not start, check your fuses, relays, connections and PM me.
This swap is not beyond any person with some mechanical experience. Some simple wiring changes, a custom mount, and everything else pretty much bolts right up. Nobody should be scared of this swap.
Email me if you have any questions.[/EMAIL]

My engine bay

What the mount should look like when it's done (for 91-93 Legends only):

Excuse the following pictures, I drove in the rain a couple days ago, and my engine compartment is a mess

This is the oil pressure sending switch wire that needs to be extended and zip tied to the radiator hose since it can no longer be ran between the timing cover and the belts.

Some of the vacuum lines (I used the RL valve cover, which needs to be swapped back to the Legend valve cover)

A little adaptor I made for the undersized fuel pressure regulator tube (in red). This picture also shows the intake temp sensor (Gray) that had to be moved to the back of the engine.

The fuel line being bent up to fit on the RL fuel rail (OPTIONAL: use your Legend fuel rail and line)

The hybrid mount, painted and installed

These are the two sensors that are swapped (in the thin red circles). You have to extend the wires about 6-8 inches to make it work

A pic of my car on the Dyno:

Scans of my first dyno run. This is untuned (AFC-II set at zeros), with one piece CAI, EGR Blocked, Throttle Body coolant bypass, Gutted and gasket matched intake manifold, gasket matched and lightly ported exhaust side of the heads, ported exhaust manifolds, stock Y pipe, no cat, and 2.5" exhaust from Y pipe back.

Torque curve with air fuel ratio

Max horsepower and torque

Air/Fuel Ratio (terrible)

RPM

Alperovich · 11-04-06, 12:16 PM

wow mike nice write up, any pictures to go along with that?

edit: haha now i see the pics

sr5guy · 11-04-06, 12:26 PM

VERY nice write up.. Now all we need is a DIY on hacking a type II intake manifold to work :gggg:

-Matt

L3GDKANG/JDM-KANG · 11-04-06, 12:28 PM

Hummmm i have an extra sedan body this might be somthing to tackle!

Mike Diaz · 11-04-06, 02:39 PM

Quote:

Originally Posted by blkonblkcpe

Give me a sticky or give me DEATH!

ok

Quote:

Originally Posted by sr5guy

VERY nice write up.. Now all we need is a DIY on hacking a type II intake manifold to work :gggg:

-Matt

Personally, after you properly gut the RL manifold, it is definitely better than the Type I or II.

I have to pull my intake manifold again for some measurements, but I really don't want to buy new gaskets for the upper, middle, and lower plenum. It's a pain in the butt. You have to use a small cut off wheel, titanium carbide grinding bits ($175), a port and polish kit ($65), and wear safety glasses. Just cut, grind, and polish until you're happy with the whole thing. It took me about 5 hours to gut and polish my intake manifold. I started to get tired in the last hour, but I took no shortcuts. I just regret not taking pictures.

Perdo31783 · 11-04-06, 03:46 PM

great write up...makes me wanna go out there and do it on my own...but i know i cant...lol

sr5guy · 11-04-06, 03:58 PM

Quote:

Originally Posted by Mike Diaz

ok

Personally, after you properly gut the RL manifold, it is definitely better than the Type I or II.

I have to pull my intake manifold again for some measurements, but I really don't want to buy new gaskets for the upper, middle, and lower plenum. It's a pain in the butt. You have to use a small cut off wheel, titanium carbide grinding bits ($175), a port and polish kit ($65), and wear safety glasses. Just cut, grind, and polish until you're happy with the whole thing. It took me about 5 hours to gut and polish my intake manifold. I started to get tired in the last hour, but I took no shortcuts. I just regret not taking pictures.

Do you think the P&P had any gains? With a gutted intake manifold would it really matter anyway? Did you loose torque/is it a dog down low? Are you planning on FI, is that the main reason you gutted it?

My type II intake is coming on monday and I'm debating on whether to P&P it or not before I install it.

-Matt

Mike Diaz · 11-04-06, 05:23 PM

Quote:

Originally Posted by sr5guy

Do you think the P&P had any gains? With a gutted intake manifold would it really matter anyway? Did you loose torque/is it a dog down low? Are you planning on FI, is that the main reason you gutted it?

My type II intake is coming on monday and I'm debating on whether to P&P it or not before I install it.

-Matt

I believe the VIS system was intended to raise gas mileage in city driving conditions. I can start off in 2nd gear, and it's actually pretty powerful right off the line. I do not believe it will hurt power down low, I actually feel that it increased power.

Forced induction is in my future, but it will most likely be a supercharger, which will replace the intake manifold.

MoisTiCaL · 11-04-06, 06:03 PM

Nice write up Diaz, You make sound so easy by the flow of the write-up. If it were only that easy.

Mike Diaz · 11-04-06, 06:52 PM

My fabricator did a great job with the mount. It only took him about an hour, and cost me $50. If I could find some RL and Legend mounts, I could get some done.

OverDrive · 11-04-06, 06:57 PM

Nice.. now we don't have to ask a billion questions.... All we have to do now is give this web address to an auto mechanic and he shoulnd't any problems installing....

course there always lifes little surprises that are left out