Honda V6 Swap

[Chris Duncan]

Looking at a Honda V6 J series swap into a S30.

 

I've worked on all the Japanese brands and have recently looked at all the Aluminum block V6's that are available in the '95 to '05 range. Of the big three Japanese brands, Toyota, Honda, Nissan, the Honda is the lightest, smallest, and most affordable.

 

The J series goes from 3 to 3.5 liter and from 200hp to 270 hp, most with the same trans mounting and flywheel configuration. So if you can configure one swap it will work for several engines.

 

Narrowed it down to a three year range. From '00 to '02 Accord. This is with coil on plug and cable Tbody. The previous years had a distributor and after this they went to DBW. Going with the J30a1 which has 200hp, it's a better fit for the series the car is being raced in. I bought a 90K mile engine from the wrecker to get started. Going to eventually buy a complete wrecked car off CL to get all the harnesses, ECU, and stuff needed for the swap.

 

Here's what I have so far.

 

It looks like the intake plenum can be turned 180 deg so the Tbody points forward. The intake ports are symmetrical so they match up. None of the bolt holes match up but it looks like they can all be redrilled/tapped or brackets made. The EGR passage will need some separate tubing if it's hooked up at all.

You could weld a Tbody flange onto the back of the plenum but the flow wouldn't be optimum. It looks like this plenum is well tuned from the factory due to the irregular spacing of all the ports where they run toward the intake manifold.

The oil filter will need a bypass because the filter hits the steering rack, the Trans-dapt 1458 looks like it will work.

A '90 to '02 4 cyl Accord flywheel bolts up to the V6 crank and fits inside the 280Z bellhousing. Don't know what clutch disc will work, it has to fit the 280Z trans input spline and fit the dimensions of the Honda clutch friction surfaces. The Honda V6 speed dual mass flywheel looks just too heavy and expensive.

There's only one problem with using a 4cyl flywheel and that is the starter ring gear. All ring gear teeth are tapered on one side to assist starter engagement. The 4cyl turns the opposite direction so the tooth taper is on the wrong side of the tooth for CW rotation. So your either going to need to flip the ring gear and grind the taper into each tooth or swap out a ring gear from a V6 flywheel. This also means the 4cyl starter wont' work, it's going to have to be a V6 starter.

The starter is going to have to mount on the trans side of the flywheel. The stock Z starter is on the engine side. There will have to be a hole in the Z bell housing and a bulge in the trans tunnel to fit, maybe with a removable panel. The rad hose engine inlet/outlet point towards the firewall also, the thermostat housing is the worst of the two and looks like it may swap with a W0133-1773260 which points directly sideways, but don't know if this one bolts up.

The motor mounts don't look too difficult. Adapters bolted to the (FWD) pass axle mount holes on one side and the A/C compressor brkt holes on the other.

The trans to engine adapter plate will be 5/8" thick 2024 or 6061. When both the trans and engine are aligned horizontally/vertically none of the bolt holes overlap which is good. None of them line up exactly which would make it easier but a partial overlap would definitely cause problems.

Disappointingly the L28 and the J30A1 weigh almost exactly the same at 350 lbs, so there's really no weight savings, which is surprising considering the L28 is a cast iron straight 6. There may be a better front/rear weight distribution considering the J engine is entirely behind the front axle centerline. The stock 280Z weight distribution is 52% fr, 48% rear on this racecar so it's a little nose heavy.

With just a rough approximation of engine location it looks like, with the oil pan bottom at the same height as stock (flush with cross member bottom), there's about 2" of hood clearance. This is with the Z trans in the stock location so the drive shaft doesn't have to be changed.

The oil pan sump is to the front with the J engine in the RWD longitudinal position. This may cause oil pickup issues in which case the sump could be extended rearwards so a pickup could be run to the back. This would also increase sump capacity.

 

The electrical is going to be the biggest hurdle. Making the A/T ECU work with a non-electric M/T. That and the elimination of emission systems like the evap. It's been done before but never with a car this old. A standalone ECU would be optimum but doesn't fit within the rules of the race series. There's going to be permanent codes but hopefully it can be kept out of limp mode.

 

Would appreciate any thoughts, ideas, opinions.

[wayverippah]

I don't want to poo poo over your idea, as I admire the ambition and thought behind your swap. But if you're only going to be in the 200-270 range, why not just stick with the L28? You can get it in that range for not too much penny (which is the reason you wanted to go with the Honda vs the other Jap brands right?). 

 

You can also get a clean VQ35 for ~700 with the added benefit of having other outfits like McKinney doing all of the fab work for you.

Edited October 19, 2015 by wayverippah

[veritech-z]

The honda j-series swap is all the rage now in the honda world.

http://www.superstreetonline.com/how-to/engine/htup-1008-j-series-engine-swaps/

 

Ever since Bisimoto did that 1000hp Oddessy van the word seems to be out. I've seen swap kits to put them into the CRX even. There is a company that's making a swap kit for the miata already, so you may save a little effort by adapting their transmission situation to your application.

 

1000hp j-series van:

 

miata j-swap kit:

http://www.superfastmiatas.com/JV6%20Miata%20Kit.html

Edited October 19, 2015 by veritech-z

[wayverippah]

Ah I misunderstood. I thought the OP was staying around stock power levels. After looking at the swap links you provided, I still think it's going to cost the same (if not more) than the tried and true L / RB / LS swaps already done...

 

Hmm... Thinking about getting an Oddessy now   Interested to see how this turns out!

Edited October 19, 2015 by wayverippah

[GeeZ]

Get a Civic.

[Chris Duncan]

I don't want to poo poo over your idea, as I admire the ambition and thought behind your swap. But if you're only going to be in the 200-270 range, why not just stick with the L28? You can get it in that range for not too much penny (which is the reason you wanted to go with the Honda vs the other Jap brands right?). 

 

You can also get a clean VQ35 for ~700 with the added benefit of having other outfits like McKinney doing all of the fab work for you.

 

It's a Chumpcar racecar so it's very constrained by cost, both by the cost rules and real world racecar costs. The J30a1 (sub 100k miles) can be had in this area for $250 from the wrecking yards. After I engineer all the swap details it will be considerably less $ than building a L28 to 200hp. In addition the Chumpcar rules practically prohibit building an L28 to that number.

 

Also wondering what the interest would be in a affordable swap ($1500 to $2000 total) that had 270 hp, more reliable, better emissions and economy, doesn't increase total weight, and better weight distribution. Just might start making a kit.

 

Plus it's just the difficulty and the fact no one has done it that's attractive. But thanks for your input anyway.

 

Just found out from j32a.com that you can flip the lower intake and it allows the whole intake to be flipped 180deg without any drilling. The EGR will have to be plumbed but it would anyway.

[seattlejester]

Would be interesting. People do forget how smooth these engines are and how powerful they are when they aren't hauling around 3000lb+. 

 

Would be quite a bit of frankensteining to get the L series transmission to work. Maybe changing to a more durable transmission may indeed be a better idea.

 

If it is indeed a chump car, you could just hump the transmission tunnel to fit the starter. It would make installing a new starter quite a pain, but an option. 

 

If the swap allowed for use of the J35 I think that would be fantastic. 300hp NA is not unheard of and quite easily attained with bolt ons consisting of exhaust work and cat deletes. 

 

Good luck, keep us posted.

[Chris Duncan]

'90 to '2000 Honda 4 cyl flywheel / pressure plate bolts up with some minor mods. Z clutch disc fits that. The Honda PP inner dia where the TO bearing hits is smaller so may have to adapt the Honda TO brg to the Z trans.

 

Z trans will adapt to the Honda engine with just one or two holes relocated. The toughest part has been finding a starter to work. Only two RWD J motor swaps that I've seen. An S2K and a Miata. And both of these have the starter from the engine side under the oil pan. Both of them the starter is hanging below the pan, and this uses a smaller flywheel so the Z disc wouldn't fit. Going to come in right where the stock Z starter is but from the other direction. This creates a bulge in the tunnel in the upper right corner below the heater fan case. Very tricky on the spacing for the starter to clear the pressure plate.

 

Thinking I'm just going to pound a bump in the tunnel for starter clearance. Have already done so to move the driver seat lower and it almost looks stock if you work at it to get it smooth.

 

Took some starter measurements thinking I'd just go to Napa and have someone pull starters off the shelf until we would find something that works. I go to the Napa warehouse location and the guy just looks at me like I'm crazy. He's got 9000 starters on the shelf, LOL! So back home and sure enough Napaonline search, no car, just "starter".... 10,000 starters.

 

But I think I've found a starter and it's not from Napa. There's probably a few of them there but there's no good easy way to figure it out.

 

The manifold flips around and clears the hood, straight symmetrical bolt up, everything else clears except the coolant outlets and the starter. After the trans / starter is adapted it's all downhill from there. Except for the electrical.

Edited October 30, 2015 by Chris Duncan

[Pharaohabq]

A VQ swap can be done Cheaper, AND you get to put in the 6 speed tranny too.  Stock will get you in the 270HP range.

[Chris Duncan]

A VQ swap can be done Cheaper, AND you get to put in the 6 speed tranny too.  Stock will get you in the 270HP range.

 

In this area the VQ is sort of rare in the junkyards and it averages over double the amount of the Honda J engines. The thing about the Hondas is that there are a lot of them in the junkyards because of the weak auto trans. Almost all of them would blow up so if the car owner didn't have the 2K to $4K to fix it the car went to salvage.

 

The VQ is better in that it came in RWD configuration so a RWD trans will bolt up so you don't need an engine/trans adapter. But with the rules of Chumpcar you are restricted to what you can spend, so making the stock Z trans work is within the rules and buying a 6 speed is not.

 

You also have to look at the cost of the donor car because you need wiring harnesses, ECU, and peripherals. Again the Hondas are plentiful on Craigslist because of the auto trans problem. Haven't looked closely at the VQ RWD vehicles but assuming they are not as plentiful as Accords and Odysseys.

Edited November 7, 2015 by Chris Duncan

[Chris Duncan]

Update on this project. (It went on the back burner for a while because of the GTRZ.)

 

The flywheel, trans, starter, and T/O bearing adapters are all done. The trans adapter is 5/8" thick 6061 with countersunk 12x1.25 allen bolts to the engine, so a flush surface for the bell housing to sit on.

 

The flywheel adapter is 2024 that is .830" thick. It bolts up with the TL dual mass flywheel bolts which are 45mm long. This was the trickiest part of the swap so far, trying to achieve enough accuracy on a manual lathe. Also assumed incorrectly that the (China) Napa flywheel was machined accurately, it was not and it has .005" radial slop where it bolts up to the stock rear crank flange. So may have to source another flywheel.

 

the flywheel is '92 to '05 accord 4 banger, as is the pressure plate. The disc and T/O bearing are 280Z.

 

The starter is a gear reduction Hi-Torque for VW van/ porsche with a larger 9T pinion. They will swap the pinion no charge when ordered direct from the manuf. The starter is clocked about 45deg on it's own flange with some extra holes drilled/tapped to do this. For better clearance to the tunnel. This causes one of the starter mount bolts to become captive, making it harder to bolt up.

 

There is also a starter adapter bracket which is 2.5" tall and bolts to the trans adapter. The starter mounts on the trans side and there's a hole cut out of the bell housing where the stock starter sits. This makes the bell housing look compromised but if you look at other manuf. trans like a G50 Porsche the bell housing is swiss cheese. Comparing the amount of material in cross section at the cutout to a G50 (turbo Carrera) it has more material so it should be okay.

 

The last main piece of the puzzle was completed very quickly last night. The T/O bearing carrier needed to be .45" longer to reach the P/P properly. Briefly thought about machining a carrier from billet steel, but got to looking at the stock carrier. Managed to find three of them in the parts bins and thought about sectioning two of them together. They look and machine like cast iron but did a mig weld test and apparently they are weldable. So it was pretty easy to just section two of them together and weld them up. I jigged them on a 4 speed front cover plate which is steel. Had to run a hone in the bore for a bit because the weld caused some slight swelling/distortion. Much quicker/easier than machining from scratch.

 

Just a few less difficult steps left to go. Engine mounts, starter bulge or cutout in the chassis tunnel, routing the radiator hoses from what is now the back of the engine, and the wiring harness. All downhill from here. Also considering a J32 or J35. There's another endurance road race series that morphed out of Chumpcar and they aren't as restrictive on the rules. The endurance racing will be a perfect test bed for this project, it worked very well with testing the brake swap and suspension mods, and it should be good to test the strength and durability of this swap. Nothing like 7 hours straight of WOT and maximum braking and G's to put a car through the wringer.

Edited May 11, 2016 by Chris Duncan

[ihiryu]

Funny.  I'm getting ready to do a J-Swapped NSX.  After much debate, we wanted to go j35a8, since it seemed the most well rounded, but the fella that makes the kit says the C32 transmission won't fit.  So we decided to move to a 32a2 since it's much easier to source, and cheaper too.

 

I know a lot of miata guys are doing J swaps using the stock miata transmission.

[Haniel20]

I used to own a acura cl type s with full bolt ons j32a2 make nice power and make really nice tq earlier.oh and they love boost.people would call me crazy but I like j series motors more than k motors.i will build me a crx si with a j32a2 and a pranks parts m90 supercharger adapter just because its simple and cheap.

[ihiryu]

WHoa, didn't know they made that.  Thanks!

[Haniel20]

WHoa, didn't know they made that. Thanks!

no problem.you should put done decent power with the supercharger.no lie the sc can be found for a hundred bucks on craigslist all the time.

[Chris Duncan]

J-SWAP SUCCESS!!!

 

Week before track day first start up. Huge vacuum leak from the EGR passages, apparently when you flip the lower intake it opens up the passage, had to tap the plenum and put a pipe plug. The EGR will be re routed externally. A bad main EFI relay from the 200K mile parts car kept the fuel pump from running at first.

 

Night before the track day, drove it for the first time, no windshield or hood at 10pm (wearing goggles) (the dash wiring is easier with the windshield out). Only minor problems, a seeping brake line from where they were re-routed and a rad hose seep. The RPM Systems modded stock ECU works normal with no limp mode (big sigh of relief).

 

Drove 1.5 hrs to the track, did a track day and drove back, no problems. It's not an LS1 but it's still scary fast and seems to be less nose heavy than the stock setup. Wider powerband, way more torque, better gas mileage due to the VTEC. Pulls hard all the way to the rev limiter (which will take some getting used to). Haven't had time to set up an electric fan, it got up to 200F but didn't overheat in stop and go traffic up a long hill (low 90's ambient). It seems to cool a lot better maybe due to the aluminum block.

 

About 8 months working part time and approx $1500

 

Don't know if I'll ever do a kit, it would take another year or so of development. May just write up the plans and a how-to. Will do a more complete post and parts list when there's time. It's already tempting to step up to the J32 and that might be more desirable as a kit. The J30 was just chosen because of the race series the car runs. The J30's are down to $100 at some wrecking yards.

 

Now I have to name the thing. Datsun J30Z? Datsun 300HZ? Datsun V-TEC-Z?

Edited July 30, 2016 by Chris Duncan

[Leon]

Great job, looking forward to seeing some photos and video! Very cool and unique swap.

[seattlejester]

Congrats! Would love to see a picture of it or in person sometime 

[JMortensen]

^^^Agreed. This sounds pretty cool.

Edited July 31, 2016 by JMortensen

[Ereschkigal]

J30Z