KPower Industries K24 swap

[Irace86.2.0]

Originally Posted by captain awesome

I thought long and hard about that. My biggest argument against it, is that you are still trying to push or pull through half the diameter of the rest of the 1.25" system. The heater core is still the bottleneck and while it may help a little I'd be surprised if you see the same results as the second hose. Of course this is all conjecture but you can only flow so much through a 5/8" hose. Also if you didn't have the means to drill or tap, Kpower sells a neck that has an added port in that exact spot for Miata swaps.



Also I think the reason you aren't seeing the same issue, is the added turbo coolant line that's allowing the system to have that second 5/8" of re-circulation. This of course is just a guess.

Just for clarity: I am suggesting adding the T to the 1.25” heater hose and running a hot line to the heater core like the OEM setup while running the current manifold supply directly to the thermostat, or someone could run the T directly to the thermostat. This would add a second line from the engine that never goes into the heater core to aid in opening the thermostat.

You are probably right that it is best to drill to add more capacity, assuming the outlet area for the 1.25” pipe and 5/8” outlet together is not larger than the hole leaving the engine, in which case, the hole is the bottleneck, and the extra hole isn’t adding much capacity, but it isn’t taking away capacity either, unlike the T setup. I just don’t know if I want to go tearing apart half the engine.

My turbo water return goes back into the block, so it only heats the engine faster and more, but it wouldn’t supply more water to the thermostat.

I’ll probably do this mod for insurance later this summer.

[captain awesome]

Originally Posted by Irace86.2.0

Just for clarity: I am suggesting adding the T to the 1.25” heater hose and running a hot line to the heater core like the OEM setup while running the current manifold supply directly to the thermostat, or someone could run the T directly to the thermostat. This would add a second line from the engine that never goes into the heater core to aid in opening the thermostat.

You are probably right that it is best to drill to add more capacity, assuming the outlet area for the 1.25” pipe and 5/8” outlet together is not larger than the hole leaving the engine, in which case, the hole is the bottleneck, and the extra hole isn’t adding much capacity, but it isn’t taking away capacity either, unlike the T setup. I just don’t know if I want to go tearing apart half the engine.

My turbo water return goes back into the block, so it only heats the engine faster and more, but it wouldn’t supply more water to the thermostat.

I’ll probably do this mod for insurance later this summer.

If the T off the passenger side hose goes to the thermostat side it should work the same as my setup. I'm not sure how you would route the hose to the other side of the block but I'm sure it's doable.

[Irace86.2.0]

Originally Posted by captain awesome

If the T off the passenger side hose goes to the thermostat side it should work the same as my setup. I'm not sure how you would route the hose to the other side of the block but I'm sure it's doable.

The other thing I didn’t think of that may or may not be influencing whether the thermostat opens and for sure warms the lower radiator pipe is my Jackson racing radiator n oil cooler combo because oil is going to the radiator. The internal coolant should heat up faster than the oil, but if the system does heat up without causing the thermostat to open then hot oil will circulate to the radiator and warm the coolant there on the driver’s side of the radiator. It would be hard to know for sure that the thermostat is opening, besides the fact that the engine appears to not be overheating. Like I already said, I’ll do the coolant mod this summer when I have some time.

[captain awesome]

Now that I'm almost at 5k miles I'm planning some power upgrades. I still haven't installed injectors for e85 as I noticed the set I bought appear to be fake even though they are sold as "legit". So I'm skipping the RDX injectors and will be jumping to ID1050x as that seems to be the preferred set for tuners. Hoping to have a set purchased and ready to start tuning with Shawn very soon.



What I really want to start doing though is build another k24a2 block for a NA 300hp goal. It sounds like the real power is in a good head so looking at 4Piston TSX CNC head, 4Piston RR3 cams, maybe a bored out fa20 TB from Maxbore or something in 70mm? I've also read that 12.5:1 pistons and rods would be a good balance for street. Still doing some math and figuring out how much ramen I need to eat for a while but was curious if any others have gone down the NA rabbit hole yet.



I would like to at some point add a supercharger if Jackson Racing finishes a kit but just staying NA is attractive for less moving parts and complexity. I imagine both options end up adding up to the same cost or close to it. Obviously the SC will be quick and easy power above the NA setup potential but again more complexity. I had a Rotrex seize up on me before so I'm still leery about going that direction.

[RedReplicant]

I'm building one on the side, I intend to run it on pump. Should be pretty healthy.

4Piston RR4 Cams
Supertech Valve Spring Kit
Wiseco 12.5:1 87mm Pistons
K1 H-Beam Rods
4Piston TSX Head

I'd have just done a stock K20A2 head if the math didn't work out extremely in favor of paying 4Piston to CNC a head.

For reference, KPower put a similar motor into a Miata years ago.

ere's a nice K24 build we recently put together. It was running on a basemap and wasn't fully sorted out until we got it on the dyno yesterday, and it proved to be a winning combo. The idea here is to show off what can be done with your typical K24A2 powered Miata if you're looking to take it to the next level.

The chassis is my blue 2000 NB, weighing 2180 lbs. with our K24 Ultimate Swap package. No changes were made to the swap kit parts list, it's all the same stuff on our website. Skunk2 Ultra Street manifold (no porting), 74mm throttle body, KMiata 4-2-1 race header. 3" intake, 3" exhaust.

Engine setup is as follows:
Stock K24 block
Wiseco 12.5:1 pistons (87.5x99mm)
K1 rods
Stock K20A2 head (RSX Type S). No porting
Drag Cartel 4 cams
Supertech valve springs
775cc FIC injectors
Tuned on pump e85 (tested at 78% ethanol)

As you can see, this combo rocks out to 9000 rpm with a torque curve that can barely even be called a curve.

We plan on throwing a 4Piston ported head and ported manifold into the mix soon which should put us comfortably over the magic 300whp mark. Can't wait to get this thing back on track in the spring.

edit: It's worth noting that this was done through a ZF 5-speed trans, Getrag stage 2 diff, and on 15x10s with 245s.

[captain awesome]

Originally Posted by RedReplicant

I'm building one on the side, I intend to run it on pump. Should be pretty healthy.

4Piston RR4 Cams
Supertech Valve Spring Kit
Wiseco 12.5:1 87mm Pistons
K1 H-Beam Rods
4Piston TSX Head

I'd have just done a stock K20A2 head if the math didn't work out extremely in favor of paying 4Piston to CNC a head.

For reference, KPower put a similar motor into a Miata years ago.

I was considering the RR3 cams based on a video 4Piston posted but maybe the RR4 is a better fit?



Are you running 91 or do you have 93 available?


What valves and guides?



What throttle body are you planning? I'm checking with Kpower to see if I would need to repin the fa20 plug or if there's more involved to switch to the Bosch 74mm.

[Irace86.2.0]

I saw a firmware and software update spring up when I was on the dyno last week, so now that the car is running I jumped at the chance thinking this would fix the fuel gauge issue. I don't have wifi in my garage or great service, so I drove to a local Best Buy to borrow wifi and did an update of the NSP and then I did the firmware, but when I went to turn on or off the car the car was stuck in a full accessories mode. I didn't have any tools, so I tried to pull fuses one by one like the EFI, fuel pump, main ign, or whatever fuse I could find to try to kill the battery/ignition. Nothing worked, and eventually the battery died. I have a little jumper, but that didn't work when I tried to add power after it dying, so I ran a mile home and back with a 10mm wrench to undo the negative battery. After leaving it for a while, and reconnecting the battery, the car would turn to the off finally, but it wouldn't do anything in accessories position. Three hours later my wife shows up and tries to jump the car, and nothing. Eventually I decide to just downgrade back from 3.03 or whatever to 3.02, and when I do that the car now turns over, but it still won't start. I have fuel pressure, I hear the fuel pump on, I just don't know if I have injectors or spark. The car is now stuck at Best Buy until tomorrow.

Any ideas on how this went so bad? I'm reading now that people pulled the coils and injector wires before doing an update, which I wish that came with a warning, but I'm unclear why. What is the problem and how would I know what the issue is if it is mechanical or software or firmware or what?

I'm like this close to just selling the car as is for a huge loss because I am so over the issues at this point.

[captain awesome]

Sorry to hear about your troubles. I did update my NSP on the laptop the other day but didn't connect to the car yet. I think I'll hold off for a minute and see how this plays out. It seems odd how the issue transpired, and I imagine it would be obvious if there were wires touching or shorting out that caused it. Sounds like that's not the case.


What's your battery voltage now? I struggled to get my car to start around 11v when my donor alternator decided to crap out. In fact I'm on my second alternator since the swap.

[Irace86.2.0]

Car turns over hooked up with jumper cables. It just sounds like there is no fuel or no spark or both.

[captain awesome]

Originally Posted by Irace86.2.0

Car turns over hooked up with jumper cables. It just sounds like there is no fuel or no spark or both.

Mine was turning over as well but not enough juice for spark from what I could tell. It wasn't as low in voltage as I thought to really be affected but turned out to be the case. I tossed a spare battery in, and just like that it fired back up. It's something I would look into, even a jumper might not be enough if the battery went that low.

[Irace86.2.0]

It is weird the car could would turn over many many times repeatedly and still be a power problem. It isn’t hiccuping or anything. It just cranks and cranks and strongly cranks.

[Irace86.2.0]

I don’t know if anyone has time to check, but I’m trying to figure out if my coils or injectors blew with the update. I’m just trying to get a baseline of what is normal.

20v multimeter - injector came back in full accessories position with 12.21v for orange wire and 0.13v on brown wire with 0.15 when turning it over.

Measured the coil harness with the coil disconnected. White wire was 0v and stayed at 0v when cranked. Black was 0.07 and dropped to 0.03 when cranked. Yellow was 0.06 and fluctuated 0.25-0.45 roughly like voltage climbed and fell or something transient. I thought there would be something constant there.

Coils were tested at 20k and 200k ohms looking at the plug as it goes in the engine, at 20k setting I got around 1.2 from left to middle, and at 200k I got 51-53 from middle to left and left to right.

I measured a Duralast coil at Autozone and got the 1.2, but only 5 or so instead of 53, but maybe their coil is bad or different.

[Ebush]

Are you sure there is enough gas in it? The one time I ran out, I drove to the post office and went in to ship some stuff. Came out and car wouldn’t start. I messed with it for two hours, gauge wasn’t even at the half way mark yet. After disconnecting the battery it finally went down below E and I realized I was out of fuel.

[Irace86.2.0]

It was topped off hours before I did the update.