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I hope this build works out!
I've been scheming this up ever since the TT4 rules came out, but don't have the cash/cajones to buy a bunch of parts just to see if it fits.
My plan was/is to buy the bellhousing adapter from Kmiata and a junkyard K24 and take off the pan/oil pump/balance shafts and just see if it fits with just a block and head. Then if there is any room then I could start working on a dry sump pan and buy a pump/belt setup.
Received the fine thread M12 bolts yesterday and was able to get the engine/adapter/trans bolted together and dropped in the car last night.
This would be much easier if I'd used a miata trans. The S2000 trans is about 3" shorter from bellhousing to shifter, so I'm having to move the engine about 3" farther back than a standard k-swap. That's a good thing overall, but adds some complications to the swap.
First is some light interference with the frame rail corner gussets (the things the v6 and v8 guys cut out) on the firewall. I'm unsure whether NASA rules allow me to cut these out, so I'm just going to do some cutting and grinding on the engine block and adapter plate to get the clearance I need. Not a big deal, but wouldn't be a problem with miata trans.
Second is that, with the trans so far back, the bellhousing has a slight interference with the top edge of the trans tunnel. NASA rules say I can't modify the trans tunnel, so I'll probably end up cutting a notch in the top of the bellhousing and then welding in a little filler piece. Again, not a big deal, but wouldn't be a problem with miata trans.
Third, and worst of all, is pan clearance. With the engine 3" farther back than a standard k-swap, the front pickup point on the Pace pan is very likely going to be a problem. At a minimum I think I need to switch to a dry sump system with the pump and hoses mounted on the intake side, which Pace offers, but I'm afraid I also need to switch to a sump pan with pickups in the center and rear instead of front and rear. That pan design actually exists for the ecotec but not for the K20, lol.
Things have been moving surprisingly fast in the past week but this is the point where I'll probably slow down and just stare at things for a while.
Pictures below are with the S2000 shifter centered in the miata tunnel hole, and with the block resting on the steering rack. Engine has a good 40-50mm clearance to the (gutted) hood, and needs to be raised about 30mm to get the bellhousing flush with the bottom of the subframe.
Ecotec pan with a shape pretty close to what I think will work. This pan wouldn't work on standard ecotec swap with miata trans and engine 3" farther forward.
A.R.E. K20 pan might be able to be modified to work. Cut off the front section of the sump and weld in a flat plate to sit above the steering rack.
I also just discovered that the pictures I've been using for the Pace pan are actually the old, original design. Here's the current design that I have on order, which has even more **** on the front of the pan and therefore less chance of working. The only drawings they have for the pan are the fully detailed internal manufacturing drawings, and they won't share those with me. So I've been kinda working blind. Thankfully my order is placed but they haven't taken my payment yet, so I shouldn't have any problems cancelling if I decide to.
Went ahead and bought a skunk2 manifold from Kmiata to use while test fitting. Also dropped in my supermiata crossflow with my custom lean brackets to see what hose routing looks like. The dry sump tank is going to fit nicely right beside the motor, behind the sway bar. I have it mocked up as a 5x20" tank that's available from a few vendors in Europe, but I think I can squeeze in one of the more common 6" diameter american tanks too.
Picked up a JDM K24A off ebay earlier this week and it just arrived today. I was looking for a <100k mile USDM K24A2 on car-part.com and all of the ones that looked good were $800 minimum with $300+ to ship and no accessories included. I was getting ready to send payment for one when I found this "62k mile" JDM K24A was on ebay for $950 shipped with full accessories included. I'm still unclear on the exact differences between this motor (RBB-2 head stampings) and the 06-08 USDM TSX motor, but this motor should easily hit my ST4 power goals... if it lasts through my dry sump learning period and I don't blow it up first.
It came with an OEM TSX header that I was able to go ahead and test fit tonight. No chance it will work with the stock honda outlet flange, but I might be able to cut the flange off and then weld a tight-radius 3" tube directly onto the collector. For anyone looking at these pictures in the future, remember I have an S2000 trans which puts the engine 3-4" farther back than the standard Kmiata setup. Clearance for this header would be worse with the kmiata engine location and a stock subframe.
I've spent a ton of time searching for K-series headers and only found one that I thought had a chance at working for my specific setup: the K-tuned "Ram Horn" header for EG swaps. It sweeps the primaries back a little toward the flywheel and I was thinking I might be able to delete the slip-on 4-2-1 lower section and replace it with a short 4-1 collector. So I found a vendor with a very open return policy and decided to give it a try. It looks super sexy, but the exit angle of the primaries isn't what I expected based on pictures. I was expecting the primaries to be pretty tight up against the block at the collector entry point but they're actually angled away from the block quite a bit, which means a nice quality merge collector would hit the subframe. The cylinder 2 pipe also gets pretty far into my dry sump tank space. I haven't given up on this one yet, but it's looking pretty likely that I'll send it back. I think I'd rather just make a custom header from scratch than hack on this ($550) header until it kinda works with a compromised collector.
Still not sure what I'll do. The hacked on TSX header will probably work but who knows what kind of power it would make. I'm getting less and less scared of just making my own header, but a friend also had the idea that I could just switch to one of the K24Z motors with the header cast into the head. They suck for trying to make big n/a power, but they can easily hit ST4 power and would make the exhaust routing a piece of cake with the stock subframe. And thinking toward the future, they seem to handle boost very well and it's super dooper easy to bolt on a turbo...
I'm finally finished with all of the work travel that's kept me busy for the past few months so I'm making some progress on the swap again. Biggest news is that the dry sump pump arrived on Saturday. It's beautiful enough that I temporarily forgot how much I paid for this thing. My first order of fittings arrived today so I was able to start getting things mocked up. Pump is currently mounted on a piece of 1/4" scrap I had in the garage. The final mount will be 1/2".
Unfortunately my planned location for the oil tank in the engine bay doesn't work. Things got way too tight with the pump in position, and these -10 and -12 fittings are huge and the hose needs more bend radius than I expected. Tank will get mounted in the passenger footwell, probably attached to the A-pillar downtube of the cage. I checked all the rulebooks for the series I plan to run and the only stipulation I could find for oil tanks and lines was that hoses in the cabin must be braided metal. Fuel tanks have to be separated by a bulkhead, but I can't find any similar requirement for oil tanks. Someone please tell me if I've overlooked it.
I started to order bulkhead fittings to get through the firewall, but I need to pass 5 hoses through and the total came out to $250 for 5 bulkhead fittings plus 10 hose ends. 10 hose ends means 10 potential leak points. Passing the hose through cheap rubber grommets was the next thing that came to mind, but then I found this product. It's a nylon plastic "cord grip" used for passing cables into industrial electrical panels. We use them all the time at work, but we use really small ones that are an ugly industrial grey. I checked our suppliers and found this black version with 1" max ID, which is perfect for -10 and -12 hose. Best part: $5 each.
I keep having thoughts of adding boost to this car in a year or two, so I decided to go ahead and overbuild the fuel system since I need to run new lines anyway.
-Converting to return style
-Karcepts rail with feed in center and return in rear port. Front port will probably get a Jiffy-Tite QD for draining the tank, for racing comp weight and/or E85.
-Radium Direct Mount Regulator on the rear port of the rail
-Fuelab 818 and flex fuel sensor under the car somewhere
-DW200 for now
Took the water pump housing to work and did some milling, and plugged the PCV port since it isn't needed with dry sump.
Returned the K-tuned header from the previous post and ordered some custom header fab parts from Cone Engineering. Collector for 1-7/8" primaries with 2.5" exit, 2.5-3" transition, and "bullet vanes" that supposedly make this cheap formed collector perform pretty close to a $300 merge collector. Total was right at $100 for all of it. I'll cut a head flange on the waterjet at work. I'm going to try to get the header design pretty close in CAD before ordering tubing bends, but that's probably going to be a waste of time since I'm aiming the collector into a pretty small hole and I don't have CAD for the unibody or subframe.
That's all the pictures for now. The JDM K24A that I bought ended up not working very well. All of the accessories are different from the USDM version, and the K24 water neck location on the back of the head was giving me firewall clearance problems. I started asking around locally for a PRB head and some of the other parts that I needed, and ended up finding a local Honda pro who had a K24A2 bottom end and a PRB sitting on his shelf in the garage, waiting for the right customer to come along. He was interested in the JDM engine for his personal racecar, so we struck a deal for him to build me a "refreshed" K24A2/PRB frankenstein motor as a trade for my JDM K24A. That engine should be ready in a couple weeks. Many excites!
Slow progress again since I've spent the last 3 weeks assembling and shipping a bunch of hub orders (I'm half of miatahubs.com.)
I placed a few hose and fitting orders and finally settled on the scavenge fittings for my oil pan. I was planning to use the Dailey Engineering machined flange elbows, but at the very last minute when the pump was shipping, I found out they're only made in -10 size and not -12 like I wanted. I'm trying to keep all of my scavenge lines -12 with as few restrictions as possible. Should have just cancelled the -10 Dailey fittings when I found out about no -12, but they're returnable and I wanted to see them in person. I tried a -10 ORB to -12 male AN adapter but it was still smaller ID than the hose, and the -12 wrench flats were too big and interfered with the pan.
Setrab banjos were the next best option I could find. They come in M22x1.5 with a face seal, which is super easy to machine and works well with the thin wall of my pan (doesn't need a machined o-ring pocket like ORB fittings.) They're sexy and awesome, but $170 for a pair of fittings and have 3 o-rings and a constant swivel to potentially leak.
Aeroquip -12 to 3/4NPT elbows have potential to leak at the threads, but they have less restriction and fewer total leak points, so they're the winner. They're also only $20 each. Since I'm making my own pan I'll be able to control the NPT tap depth and get the fitting roughly the same installed height as the other options, which gets me a safe amount above the bottom of the subframe. And I'll also be able to control the tap depth to clock the fitting where I need and still get good torque for a good seal. Returning the Setrab and Dailey fittings this week.
Made a quickie laser template to confirm oil pan clearance before starting machining. Hoping to get it machined in the next couple weeks, but our machine shop is SLAMMED right now with no signs of letting up soon. Shitty timing, but I have plenty of other stuff to work on while waiting.
And some pictures of hubs, just because. In a couple weeks these will be on pretty much all of the fastest miatas in the country.
Scratch what I previously said about not getting the pan machined for a while. I found out thursday that we were going to have an unexpected opening in the machine shop this weekend, so I rushed to get some material ordered and delivered on Friday. Spent most of yesterday and today working on it and I'm pretty happy with how it came out, especially the fact that it fits! I intentionally left the finish a little rougher than what's possible since I didn't want to overstay my welcome with the boss letting me use the machine. It took about 7 hours total for the top and bottom setups; could have easily been 10-15 hours or more for a mirror finish. Started with 42lb of aluminum and ended with 7lb. Pictures speak better than words...
Test fit in the car. It's hard to get decent pictures without a lift, but I tried.
10-31-2018, 08:32 PM
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