K-swap How-to: A by-the-book K24A2 NB2 swap build thread
#81
With the oil pump upgrade and the KTuner, looks like you're all set to rev that K24 to the 8000-8500 range. I'm working on a similar build, and am finding conflicting information about valve springs. It seems that the OEM K24 valve springs can't handle the valve velocity at those high RPMs. Folks are replacing them either with other OEM springs (K20, S2K) or with aftermarket Supertech or Ferrea. Is this something you considered doing when your valve cover was off? Or do you think it's not needed? Thanks.
The real issue on rpm for a K24 is the bottom end. With the longer stroke (vs K20), the piston speeds get astronomical really quick. And that stroke puts a lot of side-load on the piston. The stock rod bolts also cannot handle big rpm. For a car that's going to see a lot of track use, 8000 is a solid practical limit for a stock bottom end. In fact, Hondata puts 7600 in all of its K24 base tunes.
To go higher, the minimum is forged pistons and rods...which also allows you to get the compression where you want it. 12.5 is a solid practical limit for pump premium with a good tune.
PS: All of the above is from lessons learned the hard way, as well as lots of research with real people, not just the internet.
#82
Adding to my post above, here's where I see the sweet spots for K24 builds:
1) Completely stock 06-08 K24A2, with bolt-ons, 50 VTC and tune on pump premium...typically makes 235 Dynojet in FWD applications (less for RWD). RPM limited to 8000. Massive torque!
2) Same as #1, but with mild cams/springs added. Makes 250 Dynojet at 8000 rpm. Gains are from 5000 rpm and up.
3) Same as #2, but with aftermarket rods and pistons, running on E85, 13:1 compression. 270 hp at 7600 and then drops, revs to 8500. Gains everywhere vs #2.
4) Same as #4 but with K20 head (or ported TSX head). 285 hp at 8000 and holds power to rev limit. Progressive gains from 6500 and up.
For reference, the pic shows what a K20A2 (RSX-S) head does versus a K24A2 (TSX) head.
PS: If you want reliable 300 hp, sleeved bored K25 is the way. But $$$.
1) Completely stock 06-08 K24A2, with bolt-ons, 50 VTC and tune on pump premium...typically makes 235 Dynojet in FWD applications (less for RWD). RPM limited to 8000. Massive torque!
2) Same as #1, but with mild cams/springs added. Makes 250 Dynojet at 8000 rpm. Gains are from 5000 rpm and up.
3) Same as #2, but with aftermarket rods and pistons, running on E85, 13:1 compression. 270 hp at 7600 and then drops, revs to 8500. Gains everywhere vs #2.
4) Same as #4 but with K20 head (or ported TSX head). 285 hp at 8000 and holds power to rev limit. Progressive gains from 6500 and up.
For reference, the pic shows what a K20A2 (RSX-S) head does versus a K24A2 (TSX) head.
PS: If you want reliable 300 hp, sleeved bored K25 is the way. But $$$.
Last edited by AndyHollis; 06-18-2016 at 07:31 AM.
#86
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Racked the car today to knock out a few things. We got about half the exhaust built with a Vibrant flex and 3” cat. Waiting on a couple of tight-radius 90s to build the rear half of the exhaust.
FM frame rails installed:
Intake cut down to size and installed (missing one hose clamp)
It will come back over later this week to finish up the exhaust and get the sways/endlinks installed and set up properly. Once that’s done, it’s just the interior that’s left.
FM frame rails installed:
Intake cut down to size and installed (missing one hose clamp)
It will come back over later this week to finish up the exhaust and get the sways/endlinks installed and set up properly. Once that’s done, it’s just the interior that’s left.
#87
Hey guys, any final build pictures? I know we are still playing around with a couple little things, but I think we'd all love to see the 99% finished product. Such a pretty and well-rounded build.
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#88
Ive convinced myself to commit to the K swap in my 01 LS Miata. I can **** off my B series friends, And I know I'm not financially responsible for the LS3. My friend who has a Miata as well has been convinced to K swap instead of turbocharging the iron slug BP. Is 1600$ too much to spend on an 08 TSX engine ? Thats with no intake mani or exhaust and no trans obviously. Just moved back to NC so I dont have to worry about CA rules. If no one's routed the intake towards the windshield (cowl ?) I'll have to consider that
Last edited by cyruss322; 08-11-2016 at 12:50 PM. Reason: First post best post. Kmiata has the power to reveal lurkers.
#89
Ive convinced myself to commit to the K swap in my 01 LS Miata. I can **** off my B series friends, And I know I'm not financially responsible for the LS3. My friend who has a Miata as well has been convinced to K swap instead of turbocharging the iron slug BP. Is 1600$ too much to spend on an 08 TSX engine ? Thats with no intake mani or exhaust and no trans obviously. Just moved back to NC so I dont have to worry about CA rules. If no one's routed the intake towards the windshield (cowl ?) I'll have to consider that
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#91
I live in NC and have sold a number of k20 and k24 engines. The last '06 K24A2 I sold for $1200, that was with ~130k miles but very good leak down numbers. That was with manifolds, injectors, coils, etc.
$1600 seems a bit high to me, unless it has extremely low mileage.
You can buy a whole wrecked TSX for $1600...sometimes
$1600 seems a bit high to me, unless it has extremely low mileage.
You can buy a whole wrecked TSX for $1600...sometimes
#92
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I just bought a running driving 03 RSX type-S last week for $2500 that was hit in the front. Radiator support, passengers fender, and hood is trashed, but it runs and drives just fine. It has a 05-06 motor in though...K20Z1, not the 03-04 K20A2. Detailed threads to follow from me when I have time to post a write up and photos.
Craigslist, man. Dime a dozen.
Craigslist, man. Dime a dozen.
#93
I just bought a running driving 03 RSX type-S last week for $2500 that was hit in the front. Radiator support, passengers fender, and hood is trashed, but it runs and drives just fine. It has a 05-06 motor in though...K20Z1, not the 03-04 K20A2. Detailed threads to follow from me when I have time to post a write up and photos.
Craigslist, man. Dime a dozen.
Craigslist, man. Dime a dozen.
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#98
At MATG right? Sounds good, we're here whenever you're ready.
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#99
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Post 6:
Final update, just buttoning up loose ends.
We got about half the exhaust built with a Vibrant flex and 3” cat.
The other half is built out with a few tight-radius 90* bends and a Magnaflow 12579 (3" in/out, twin 2.5" internal chambers). It is OEM quiet at idle, near-OEM at cruise, and rowdy in VTEC.
Nice and centered.
FM frame rails installed:
Intake cut down to size and installed (missing one hose clamp)
On to the interior. This car was pretty ratty inside, even for 130k miles, so Andrew elected to go all out.
Starting with a Blackbird Fabworx GT3 bar. This is the only NB bar that is glass-window compatible AND has a welded harness bar, so it's the obvious choice.
All the HVAC goes back into place after the wiring is complete.
New Pioneer touch-screen head unit with SiriusXM support, Spotify control, Bluetooth audio, and a ton more. I will bug Andrew to post more about the audio system if there's interest.
We did a carpet kit from a company in the UK that included a full under-felt kit:
And way nicer carpet than what originally came in the car:
Tan Probax Elise seats round out the upgrades here.
Outside the car, a fresh Robbins canvas top replaces the old worn-out vinyl.
The new 8,000rpm rev limiter spawned a gauge upgrade from Revlimiter. Rx8-style faces with realigned needles, new 8,000rpm limiter, and the tach range expanded to 9,000rpm. Very OEM+ to match the overall build.
After a complete cut/seal/polish/wax job, the car is now ~98% complete. There are still a few details to be ironed out (idle valve, A/C support, dyno tuning, possibly cams/valvetrain later on) but this is essentially the finished product. Pretty clean car, but that's what you get when you strip a car from the rear bulkhead forward and replace 80% of it
PS: Props to those of you who can figure out what the license plate means
Final update, just buttoning up loose ends.
We got about half the exhaust built with a Vibrant flex and 3” cat.
The other half is built out with a few tight-radius 90* bends and a Magnaflow 12579 (3" in/out, twin 2.5" internal chambers). It is OEM quiet at idle, near-OEM at cruise, and rowdy in VTEC.
Nice and centered.
FM frame rails installed:
Intake cut down to size and installed (missing one hose clamp)
On to the interior. This car was pretty ratty inside, even for 130k miles, so Andrew elected to go all out.
Starting with a Blackbird Fabworx GT3 bar. This is the only NB bar that is glass-window compatible AND has a welded harness bar, so it's the obvious choice.
All the HVAC goes back into place after the wiring is complete.
New Pioneer touch-screen head unit with SiriusXM support, Spotify control, Bluetooth audio, and a ton more. I will bug Andrew to post more about the audio system if there's interest.
We did a carpet kit from a company in the UK that included a full under-felt kit:
And way nicer carpet than what originally came in the car:
Tan Probax Elise seats round out the upgrades here.
Outside the car, a fresh Robbins canvas top replaces the old worn-out vinyl.
The new 8,000rpm rev limiter spawned a gauge upgrade from Revlimiter. Rx8-style faces with realigned needles, new 8,000rpm limiter, and the tach range expanded to 9,000rpm. Very OEM+ to match the overall build.
After a complete cut/seal/polish/wax job, the car is now ~98% complete. There are still a few details to be ironed out (idle valve, A/C support, dyno tuning, possibly cams/valvetrain later on) but this is essentially the finished product. Pretty clean car, but that's what you get when you strip a car from the rear bulkhead forward and replace 80% of it
PS: Props to those of you who can figure out what the license plate means