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.