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K series Miata swap

Old 03-21-2013, 06:46 PM
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Originally Posted by magicdc2 View Post

2200 lb. with driver, and 230 whp, 190 wtq with 100% OEM Honda engine/reliablility. Thats not going to happen with an S or NC, especially at the price point we are going for.
Get this running and have a kit sorted for Miata. Now install kit in Catfish. Lose another 500 lbs. = WINNING
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Old 03-21-2013, 06:55 PM
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99-up is a returnless fuel system... Correct? I'm sure the stock lines are fine for 250hp. Just need honda injectors and upgraded fuel pump.
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Old 03-21-2013, 07:53 PM
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Originally Posted by natedawg View Post
99-up is a returnless fuel system... Correct? I'm sure the stock lines are fine for 250hp. Just need honda injectors and upgraded fuel pump.
If this is the case, even better. Haven't really look at the lines much yet, lol.
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Old 03-21-2013, 07:54 PM
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Originally Posted by magicdc2 View Post
FTB – the K has VVT (variable valve timing) on both intake and exhaust cams, but it has VTC only on the intake cam. This allows for continuous VTC cam angle adjustment to optimize power/torque at any point in the power band. It used oil pressure to either advance or retard timing by 25 degrees in either direction. Until VTC existed, tuners were limited to one set cam angle for the entire powerband, such as other DOHC VTEC B series and F series engines. A K engine tuner can set the intake cam advance at any angle at any place on the MAP.

I don’t believe MS is able to control VTC, which is one reason why a K series EMS must be used.
Pretty sure MS can control both the VTAK and the VVT. I know it can do VVT because it can run the 01+ intake cam advance VVT. And I'm pretty sure I've seen the ability to run VTAK mentioned in MS literature before.
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Old 03-21-2013, 08:00 PM
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Originally Posted by emilio700 View Post
Assuming VTC is just an on/off MAP/RPM table MS3 should do it. The VICS for the 99-00 Miata intake manifold is also just an RPM switch we run off a 1D table but there are extra 2D tables. I assume it's just a simple grounding/5V circuit and not PWM or PID. VVT on two cams also no problem. If we build a K5 it will be with an MS3pro. If VTC is PID then it might be an issues because I think the MS3pro can only run two cam PID's, not three.
VTC requires more that on/off functionality. You have 50 degrees of sweep in the gear, and it can be programmed to adjust at 5 degree increments, for a total of 10 positions.

Typically under WOT, the low cam is tuned first, then the high cam. Each cam's VTC position is tuned to gradually give you more advance and thus more power. I don't know much about MS, but I would be surprised if it could handle a feature like this that's completely foreign to a BP motor.

This first car is just going to use Kpro with a universal jumper harness. I've also spoken with Rywire a couple times about making a full plug and play solution.
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Old 03-21-2013, 08:03 PM
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Originally Posted by magicdc2 View Post
For fuel, yes you will need a fuel pressure regulator and some lines. Older Honda chassis are like Miatas with the return fuel system, but the K uses a returnless system. Like an EG, EK, DC swap, you convert the car to returnless. You just need a $150 regulator, some AN lines, and a bigger fuel pump most likely. For our first swap we are using the stock S2000 fual rail and injectors.

For the ECU, yes, a Kpro’d ECU disables the immobilizer, and there is no need to obtain a VIN# to do so. We talked about using MS for this, but that’s not going to be possible for a few reasons. The whole car will run on a Kpro ECU.

FTB – the K has VVT (variable valve timing) on both intake and exhaust cams, but it has VTC only on the intake cam. This allows for continuous VTC cam angle adjustment to optimize power/torque at any point in the power band. It used oil pressure to either advance or retard timing by 25 degrees in either direction. Until VTC existed, tuners were limited to one set cam angle for the entire powerband, such as other DOHC VTEC B series and F series engines. A K engine tuner can set the intake cam advance at any angle at any place on the MAP.

I don’t believe MS is able to control VTC, which is one reason why a K series EMS must be used.
You're calling VTC is what miata guys call VVT because that's what its called on the 01+ BP.
What I was saying is that the K has VTEC on both cams and VVT, which is the variable timing on the intake cam. The MS3 can natively control VVT, or you could use a VVTtuner with older MS but idk why you would do that.
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Old 03-21-2013, 08:23 PM
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Originally Posted by Full_Tilt_Boogie View Post
You're calling VTC is what miata guys call VVT because that's what its called on the 01+ BP.
What I was saying is that the K has VTEC on both cams and VVT, which is the variable timing on the intake cam. The MS3 can natively control VVT, or you could use a VVTtuner with older MS but idk why you would do that.
Interesting. To what degree of advancement? Does it move just between two positions? A quick google search seems to say so.
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Old 03-21-2013, 08:59 PM
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Originally Posted by magicdc2 View Post
Interesting. To what degree of advancement? Does it move just between two positions? A quick google search seems to say so.
You seem to be under the impression that the MS3pro is limited to OEM NB2 requirements? There are MS1 & 2 PnP users here but most DIY their own boxes.

In any case, the MS3pro will handle mutliple PID's and 2D PWM tables. Paging Joe Perez.
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Old 03-21-2013, 09:03 PM
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How much fuel pressure does the honda motor run?
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Old 03-21-2013, 09:25 PM
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Originally Posted by triple88a View Post
How much fuel pressure does the honda motor run?
approx 50psi from what i see.

nb is 48-56psi

Last edited by natedawg; 03-21-2013 at 09:55 PM.
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Old 03-21-2013, 09:27 PM
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The stock miata setup runs 43ish psi so gotta find a way to boost it.

As said NBs are returnless.
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Old 03-21-2013, 09:57 PM
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Originally Posted by magicdc2 View Post
Interesting. To what degree of advancement? Does it move just between two positions? A quick google search seems to say so.
The MS3 supports closed-loop VVT for up to four camshafts. So it'll drive everything from a simple 4-banger with only one variable cam all the way up to a Quad-OHC V8 with adjusters on every cam.

Here is the documentation: Megasquirt-3 MS3 Variable valve timing (VVT / VANOS)

And as Emilio mentioned, it can also drive several PWM outputs open-loop, based on two-axis tables of your choosing. This was how the initial alternator-control system was implemented on the NB. You could also use it to control a Subaru fuel pump, or anything else that needs a PWM feed that varies with some combination of engine parameters.

As for VTEC, that's just a simple on/off control, so it's pretty much a no-brainer.
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Old 03-22-2013, 03:34 AM
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Originally Posted by Joe Perez View Post
As for VTEC, that's just a simple on/off control, so it's pretty much a no-brainer.
^Especially if you dont do map switching. Honda did, but its probably not necessary.
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Old 03-23-2013, 11:25 AM
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Originally Posted by emilio700 View Post
My notes show that a fully dressed BP is about 296#. Anyone know what a fully dressed K20 and K24 weighs?
Originally Posted by locostusaforums
Honda K24A1 engine + intake + exhaust manifold + alternator + starter (no flywheel) = 283 lbs
They also mentioned 405lb with the transaxle.
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Old 03-23-2013, 11:41 AM
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So roughly the same weight for a bunch more engine, awesome.
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Old 03-23-2013, 01:34 PM
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You can tune cam timing to be based only on a 3D map with RPM and MAP as axes. Because fueling is also primarily based also on RPM and MAP, there will be no need to tune multiple maps for different VTC (VVT) settings. A given combo of RPM and MAP yield a fixed VTC angle, and thus a fixed VE.

One would obviously tune WOT for max torque at all RPMs, but at MAP < 1 atmo, e.g. 70 kPa, one could instead tune VTC for fuel economy, e.g. minimum overlap in the midrange. This is how I tuned my miata VVT.

I believe Honda tuned separate maps for different VTC settings for 2 reasons:
- if VTC fails and is stuck in a given setting
- the VTC map is different during warmup to reduce emissions

The above implies the VTC setpoint can change for a given combo of MAP and RPM, so there's a need for multiple spark and fuel maps. The ECU interpolates between the maps, using the actual VTC angle. Basically a 4D map for spark and fuel. I've done this 4D map interpolation, at work, for a totally unrelated thing.
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Old 03-24-2013, 02:46 PM
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Updates and new pics here: K24 Miata swap... finally a reality - Page 2 - K20A.org .:. The K Series Source . Honda / Acura K20a k24a Engine Forum

Crossmember, mounts, and steering is all done. Header update coming shortly
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Old 03-24-2013, 03:09 PM
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Looks like unmodified steering geometry would require a raised engine (even with a custom pan), engine 4" rearward (shorter PPF, shaft, FW mod...) or front wheels 4" forward (with modded fenders).
(4" taken from the column elongation, so it's probably 3.x", still a huge change).

Hmm, will be interesting to hear how the steering mod feels on track (unless it's well known due to copy of V8R?).
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Old 03-24-2013, 08:45 PM
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wow impressive.
can't wait to see when this is finished.
does it sit higher than the stock engine? i wonder how this will handle
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Old 03-25-2013, 05:41 AM
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magicdc2,

You have a great project here, but I suggest you stop at this point and reconsider your steering rack placement/geometry, steering column extension and motor mount placement/construction.
If you (or anyone planning a swap) are not going to do the swap correctly, then just leave the Mazda engine in the car and boost it.
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