The "J" Swap

[Velocitized]

Well, I’ll start with a little background. I bought the car in 2/08 with a salvage title due to theft and a blown motor due to high school student PO, and the interior was pretty trashed. Let’s just say this car has been driven hard and put away wet. The good news was, it had a Comptech Supercharger, headers and intake on it, and after a thorough inspection, there were no signs of an accident.

This is when I first got the car.

Here is the engine that was pulled out.

At the time I looked into many options as to how to get the car back on the road, putting in a C27A from a ’95 Accord V6 would be a simple bolt in and the car would move around but not really have much power; the C27A is rated at about 170 HP. Put in a newer Honda J-series 60 degree V6, I looked at tons of photos of the J-series block and the NSX transmission and from the pictures it looked like this might very well be an option but at the time I couldn’t get my hands on a J-series and I hadn’t taken the NSX transmission out yet to try fitting the two together. I could just pull the motor and start tearing it down and see what the rebuild was likely to cost, from what I could tell I was in the $6,000+ range for a rebuild depending on what was bad inside my motor and the price could quickly go north. I ended up finding a complete motor and transmission on Prime from a member who got into an accident. So, in 3/09 I had the car back on the road and started addressing all the other issues and I have been enjoying the car more and more as each issue is resolved.

One issue that I could never resolve was a CEL while in sustained VTEC for low VTEC oil pressure on the front head. I replaced the entire front VTEC solenoid assembly but still the CEL would come on if I stayed in VTEC. Then this past spring I was driving the car one Monday and took some fun spirited drives, then on Tuesday I start the car and hear a quick rattle for a minute from behind my head when I started the car, I back out of the garage get out of the car and look around and underneath for something loose and I see nothing, so I head down to the store and at the end of the block I hear it again only this time I know EXACTLY what that sound is, it is a rod bearing, damn, I thought I was going to throw up right there. I gently drive the car back to my house and put it away, about a week later, after I could stomach it, I went back in the garage to confirm my nightmare (maybe this was a dream)….nope. I started the car for a second and heard that knock, shut it off!

Now what?

Stay tuned..

 

[Mac Attack]

Can't wait to see more!

Dave

 

[Rogue MotorSports]

Great to see. Cant wait for the updates

 

[mr envy]

just a fyi the c27 WILL NOT bolt up, no other c series shares the same bolting patterns as a c30a/c32b, the earier j series however shared the same bellhousing pattern as Rogue Motorsport and you are aware of

 

[A.S. Motorsport]

just a fyi the c27 WILL NOT bolt up, no other c series shares the same bolting patterns as a c30a/c32b, the earier j series however shared the same bellhousing pattern as Rogue Motorsport and you are aware of

Are you sure? I actually believe it will bolt right on the bell housing, C27A casting is near identical to C30A

 

[Velocitized]

just a fyi the c27 WILL NOT bolt up, no other c series shares the same bolting patterns as a c30a/c32b, the earier j series however shared the same bellhousing pattern as Rogue Motorsport and you are aware of

I am 99% certain that the C27A, C30A, C32B and J30A, J32A, J35A will bolt up to the NSX bellhousing. The C32A and C35A will not. I will be using a J32A2 from a 2003 Acura TL Type-S.

- - - Updated - - -

So, as fate would have it, I was surfing the forums looking for a pair of rods since if my rod bearing spun I may need a rod and Acura doesn’t sell just a rod I would have to buy the entire piston/rod assembly and not knowing whether I would need a front or rear rod I was looking for both.

That is when I came across a thread by Rogue MotorSports who, low and behold, is putting a J-series in an NSX, his thread completely consumed me and I read through the entire thread about six times. I had to talk to this guy! When Rogue discovered, by chance that the NSX transmission would indeed bolt up to the J-series block, my suspicion was confirmed. This swap is entirely possible I thought. Wow! No custom axles, no custom shift linkage, two of the four motor mounts bolt right on and a third hits on two out of three bolts! Wow! I had to talk to this guy! On the phone with Rogue we discussed the J-swap, I mentioned that I had looked into it back in 2008 and how excited I was that my suspicion was correct in that the J-series would bolt up to the NSX transmission.

In my mind it made sense. The C30A was basically a bored and stroked C27A from the 88-90 Acura Legend only now with DOHC and VTEC. Honda reused the C27A again in the 95-97 Accord V6, they needed a V6 sedan. Then in 97 Honda came out with the J30A 60 degree V6 for the Acura 3.0 CL and although they changed to a 60 degree V6 (the C engines are 90 degree with offset con rod pins so they act like a 60 degree) with SOHC, there really wasn’t much need to change the transmission and they probably did a lot of testing with the J-series bolted to the 95-97 Accord V6 transmission, who knows maybe they even used the NSX transmission.

Now, Rogue didn’t have a flywheel or axles to test with and I happen to have both lying in my garage, somewhere. I found my axles and shipped them off to Rogue and I took my flywheel and headed to my favorite Automotive Recycling Yard and asked them if I could see if my flywheel would fit on a J32 or J35 and they asked me what it was from and I told them it was from an NSX and they said it won’t fit, so I asked if I could try anyway and see if maybe I could have an adapter made and they said sure, let’s go. So we took off the flex plate, I had already confirmed that the crank flange bolt pattern was the same, it is actually the same for many Honda B, C, D, F, G, H and J engines, and wouldn’t you know it, the flywheel fit but it wouldn’t go on all the way because of the pilot bearing in the flywheel, but it would work. I ordered my engine from them right there! A J32A2 from an automatic transmission Acura TL Type-S with the wiring harness, exhaust J-pipe, alternator, A/C compressor, throttle bodies and PCM.

I am doing a J-swap in my NSX!

Here is the J32A2 sitting next to a NSX 5 speed trans

Okay, let's get started...

 

[Nefarious]

I'm really excited to follow your build. Best of luck!

 

[illwillem]

Yes. This is awesome. You and Rogue are pioneering new frontiers. Please post all the info that you can even the little stuff that seems unimportant at the time will help others tremendously in the future.

 

[NetViper]

The race is on. Who will finish the swap first!

What is the J32A2 anyway? how much HP? TQ? etc?

 

[Velocitized]

I have the following goals for this build:

1. Do NOT modify anything on the NSX, only modifications are to the J-motor. In other words, make the J-motor fit the NSX, not the NSX fit the J-motor.
2. All systems in the NSX should work as they did before the swap. Cruise control, climate control, traction control, EVAP/emissions, all gauges, etc.
3. The swap must be completely reversible without any signs of a previous swap.
4. Use stock NSX exhaust cats and cat back exhaust.
5. Document EVERYTHING I do.

My NSX is a 1991. NSX’s from 1991-1994 were all OBD-1, drive-by-cable cars and there were roughly 5000 of them sold in the US. (from 1995 -2005 there were roughly 4000 NSX’s sold in the US). In 1995 all NSX’s switched to OBD-2 and drive-by-wire.

The J32A2 motor from the Acura 01-03 CL-S/02-03 TL-S and the J35A3 from the Acura 01-02 MDX are both drive-by-cable engines and were considered as options. I chose the J32A2 over the J35A3 for its shorter stroke 86mm vs. 93mm. I feel the J32 better matches the driving dynamics and gear ratios of the NSX and that the shorter stroke will rev faster and higher. (note: the stock NSX engines have a 78mm stroke, however the stroker kits are either 84mm or 86mm)
All J-series motors are OBD-2, so I will have to do some wiring, but again, I am only willing to modify the J-series wire harness, I will not cut into my NSX wire harness.

So, I see the big hurdles as:

1. Clutch and flywheel
2. Front and Passenger motor mounts
3. NSX intermediate shaft mount
4. OBD-2 immobilizer delete
5. Modifying the J32 OBD-2 wire harness to fit the OBD-1 NSX.

First up, the flywheel, here is an aftermarket NSX flywheel that came off my old engine.

Notice the pilot bearing is pressed in from the back and sits flush against the NSX crank flange.

The J32A2 crank flange has a hub sticking out of the crank flange.

I pressed the pilot bearing out of the NSX flywheel and it is the same size as the hub sticking out of the J32A2 crank flange.

I polished up the J32A2 crank flange hub a bit (didn’t touch the NSX flywheel)

And the flywheel slips on!

- - - Updated - - -

The race is on. Who will finish the swap first!

What is the J32A2 anyway? how much HP? TQ? etc?

I don't think it is a race, more like a collaboration.

In 1997 Honda introduced their 60 degree, SOHC, J-series motor and it has become their workhorse. You will find the J-series available in just about every Honda and Acura car, truck, mini-van or SUV. They range in size from 3.0 to 3.7 liters and horsepower from about 200 HP, 200 TQ to 300+ HP, 300 TQ.

http://en.wikipedia.org/wiki/Honda_J_engine

The real kicker....you can pick one up for about $500 at your local auto recycle yard.

 

[mr envy]

100% certain c27 is different. NSX blocks were unique in their bolt pattern a matcher up a c27,c25 and early turbo c20 and the bolt pattern are different. but build looks amazing cant wait to see more

 

[dablackgoku1234]

Curious, is the end goal a stock J32 or a Frankenstein J36?

 

[ProOnThaSnow]

In for Updates. I absolutely love stuff like this! With the aftermarket slowly growing for the J series engines, this may be a more viable swap for people looking for performance gains down the road.

 

[Velocitized]

The NSX 5 speed input shaft slips inside the hub sticking out of the J32A crank flange. The input shaft has an OD of about 20mm and the crank hub has an ID of about 24mm. Looks like I'll need a custom pilot bushing.

 

[GRacer]

subscribed !! thanks

 

[ProOnThaSnow]

??

http://www.amazon.com/Dayton-3FJE1-Pack-Bronze-Bushing/dp/B00F1ZCO9Y

May need to have it machined to be a little narrower as you didn't give that dimension, but these would take a- lot of trouble out of machining an entire one.

 

[DreamPowered]

You and rouge are doing a great job. Keep up the good work. Maybe once you guys have worked out the mounts or in the mean time you can contact HASport. I know they have done alot of k swaps to older chassis and might be able to help or even assist with the manufacturing of the mounts for a j swap nsx kit for those who would be interested.
Just an idea.

 

[MinnesotaR6]

wow excited to see the end results!

 

[Velocitized]

Great to see. Cant wait for the updates

Thanks for the encouragement. I probably wouldn’t have started it if I hadn’t come across your build thread.

- - - Updated - - -

I'm really excited to follow your build. Best of luck!

Thank you.

- - - Updated - - -

Yes. This is awesome. You and Rogue are pioneering new frontiers. Please post all the info that you can even the little stuff that seems unimportant at the time will help others tremendously in the future.

Thanks, I plan to document and share as much as I can. If you have a question or need more detail on something, just ask and I will see what I can do.

- - - Updated - - -

Curious, is the end goal a stock J32 or a Frankenstein J36?

I will be leaving the J32 stock for the most part. I plan to reuse my NSX Comptech intake and exhaust. I will eliminate the J32 j-pipe that connects the front and rear exhaust manifold into a single pipe and convert to dual pipes like the stock NSX exhaust, using the stock NSX cats. Later I may upgrade to a later style J-series intake manifold.

- - - Updated - - -

What is the J32A2 anyway? how much HP? TQ? etc?

The J32A2 is factory rated at 260 hp @ 6200 rpm and 232 lb•ft @ 3500-5500 rpm and the NSX C30A is factory rated at 270 bhp @ 7100 rpm and 210 lb•ft @ 5300 rpm. Both ratings are not SAE adjusted. Both engines use a variable volume intake system but the J32A2 is SOHC and the VTEC is only on the intake side.

- - - Updated - - -

??

http://www.amazon.com/Dayton-3FJE1-Pack-Bronze-Bushing/dp/B00F1ZCO9Y

May need to have it machined to be a little narrower as you didn't give that dimension, but these would take a- lot of trouble out of machining an entire one.

Thank you. The pilot bushing needs to be about 12-14 mm long. I found an SAE bushing at McMaster.com that I think will work but it is 16mm long, so it will have to be cut down.

- - - Updated - - -

You and rouge are doing a great job. Keep up the good work. Maybe once you guys have worked out the mounts or in the mean time you can contact HASport. I know they have done alot of k swaps to older chassis and might be able to help or even assist with the manufacturing of the mounts for a j swap nsx kit for those who would be interested.
Just an idea.

Thank you. I have talked with Rogue about how he is doing his mounts and we have shared some ideas. I have talked with several fabricators in my area and most are not interested in doing one-off jobs, but I did find a fabricator who specializes in prototypes and product development and I have talked to him about the project.

 

[Rogue MotorSports]

You and rouge are doing a great job. Keep up the good work. Maybe once you guys have worked out the mounts or in the mean time you can contact HASport. I know they have done alot of k swaps to older chassis and might be able to help or even assist with the manufacturing of the mounts for a j swap nsx kit for those who would be interested.
Just an idea.

I spoke with hasport a few times before I started the project, and they were not interested in doing the mounts. The same problem I ran into when I did the prelude. I contacted 2 of the biggest aftermarket mount companies in the US and offered them the car, motor, trans and offered to buy 10 sets of mounts and they wouldn't build them. They said the demand wasn't there and it wouldn't be a wise business choice on there end.

 

[Velocitized]

I spoke with hasport a few times before I started the project, and they were not interested in doing the mounts. The same problem I ran into when I did the prelude. I contacted 2 of the biggest aftermarket mount companies in the US and offered them the car, motor, trans and offered to buy 10 sets of mounts and they wouldn't build them. They said the demand wasn't there and it wouldn't be a wise business choice on there end.

If there is demand, I would have no problem putting together a motor mount swap kit.

 

[93SilverBlitz]

J Swap

If there is demand, I would have no problem putting together a motor mount swap kit.

David, great work on your research so far! Can't wait to see it all comes together.
Sorry didn't make it up to the Street of Dream that weekend, had family emergency.
I'll be sure to come up one of these weekend to see your progress, can't wait to have you on a drive soon.

Hmmm since you're the master at swapping these now, can you put in a
VR38DETT in my NSX? LOL.

 

[mr envy]

haha I like this sort of stuff. Im just re shelling a c30a hehe, no idea why you guys are staying away from them tho

 

[Velocitized]

I found a pilot bushing made out of SAE 841 Oilite that is 20mmx24mmx16mm but I need it to be 20mmx24mmx12mm so I pulled out the belt sander, slapped on some 80 grit and about 5 minutes later I was good to go.

I took a look to see how the front mount would line up since I had the transmission on. Two of the three bolts bolt into the transmission, the third bolt hole falls in between two bolt holes on the block.

So, I am thinking about a bracket like this. This will probably be machined out of steel plate.

The bolt mating surfaces are all on the same plane, so the bracket will have to have an offset.

 

[adrenaline_nsx]

is there a reason you went with the auto motor instead of the manual? Are you going to be using Aem Ems for tuning? I may be jumping into the j-series after my motor gives out. Im interested in doing a twin turbo J36 stroker with some aftermarket low compression pistons. Here is a thread comparing the j37 rods, crank, pistons to the j32. As you can see the forged j37 parts look a lot beefier.

http://cl.acurazine.com/forums/showthread.php?t=884537