K series Miata swap
03-21-2013, 06:54 PM
#144
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.
I don’t believe MS is able to control VTC, which is one reason why a K series EMS must be used.
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03-21-2013, 07:00 PM
#145
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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.
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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03-21-2013, 07:03 PM
#146
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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.
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.
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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03-21-2013, 07:23 PM
#147
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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.
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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03-21-2013, 08:57 PM
#152
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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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03-23-2013, 12:34 PM
#156
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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.
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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03-24-2013, 01:46 PM
#157
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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
Crossmember, mounts, and steering is all done. Header update coming shortly
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03-24-2013, 02:09 PM
#158
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?).
(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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03-25-2013, 04:41 AM
#160
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.
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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