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-   -   K series Miata swap (https://www.miataturbo.net/engine-performance-56/k-series-miata-swap-71588/)

AndyHollis 12-13-2014 07:25 PM


Originally Posted by ctdrftna (Post 1189305)
Itbs with k&n sprint car airbox is the route I will be taking mine.

60mm kinsler's with 12" runners

Tuning with KPro? or something else (AEM?)?

ctdrftna 12-13-2014 08:11 PM

Kpro, Alpha N

viperormiata 12-14-2014 01:15 PM

In4 air conditioning mod.

njn63 12-14-2014 01:23 PM

Did everyone see the new kpro 4?
K-Pro 4

Looks like I need to add a flex fuel sensor to my list of parts needed. :party:

AndyHollis 12-14-2014 05:12 PM


Originally Posted by njn63 (Post 1189449)
Did everyone see the new kpro 4?
K-Pro 4

Looks like I need to add a flex fuel sensor to my list of parts needed. :party:

Yep. That makes my life a LOT easier.

Also loving the new support for digital dashes like AIM and Racepak, as well as live tuning and autotune.

My KPro is already in CA getting upgraded.

ctdrftna 12-14-2014 07:10 PM

how would i go about getting a vehicle speed signal to the Kpro with a NA that uses mechanical speedo?

emilio700 12-14-2014 07:18 PM

K-Pro-4 here too when the time comes.

Leafy 12-14-2014 08:01 PM


Originally Posted by ctdrftna (Post 1189500)
how would i go about getting a vehicle speed signal to the Kpro with a NA that uses mechanical speedo?

The NA gauge cluster still produces an electrical speed pulse for the cruis control to work. I think its like 4 pulses per rotation of the speedo cable I forget what that is in pulses per mile. You need to use a pullup resistor to get the signal to work with most ecus.

AndyHollis 12-14-2014 08:02 PM


Originally Posted by ctdrftna (Post 1189500)
how would i go about getting a vehicle speed signal to the Kpro with a NA that uses mechanical speedo?

From the new KPro V4 release notes:


Speed sensor input

A speed sensor input can be directly connected to the KPro4 and sent to the ECU. This is configurable to any pulse based sensor and eliminates the need for a stock speed sensor.
Still need to convert it from mech to digital, but now at least there is configurability.

Worst case, you can do the magnets around the driveshaft thing...Rostra sells 'em for their universal cruise control. I have a set, BNIB, if you need. Was my backup plan when my CRX sensor was being flaky.

ctdrftna 12-14-2014 08:18 PM


Originally Posted by AndyHollis (Post 1189510)
From the new KPro V4 release notes:



Still need to convert it from mech to digital, but now at least there is configurability.

Worst case, you can do the magnets around the driveshaft thing...Rostra sells 'em for their universal cruise control. I have a set, BNIB, if you need. Was my backup plan when my CRX sensor was being flaky.

So if i run a 99+ electronic speed sensor, i can run the wires directly to the Kpro-4 and that can configure it correctly and send it to a digital dash?

AndyHollis 12-14-2014 08:30 PM


Originally Posted by ctdrftna (Post 1189513)
So if i run a 99+ electronic speed sensor, i can run the wires directly to the Kpro-4 and that can configure it correctly and send it to a digital dash?

I believe so. Download the latest KPro software and see how it handles it for V4 boards (looks like you need the latest Beta version to get that stuff).

I'll likely have a definitive answer in the next week or so, as I am in the process of wiring my swap up right now. You *can* run w/o a speed sensor, but it works better with one. Especially idling.

KMiata 12-15-2014 08:03 PM


Originally Posted by AndyHollis (Post 1189515)
I believe so. Download the latest KPro software and see how it handles it for V4 boards (looks like you need the latest Beta version to get that stuff).

I'll likely have a definitive answer in the next week or so, as I am in the process of wiring my swap up right now. You *can* run w/o a speed sensor, but it works better with one. Especially idling.

Good info guys. And for the record, I'm running my car with no speed sensor, with no issues at all, even at idle. Speedo works perfectly without touching the circuit.

Obviously there are some advantages to sending a VSS signal to Kpro, but we haven't gotten that far because we haven't needed to. Good to know Kpro 4 will support other sensors though.

KMiata 12-15-2014 08:05 PM


Originally Posted by viperormiata (Post 1189448)
In4 air conditioning mod.

Yes, this is on the agenda. But priority right now is getting some header options in stock for people, as well as a couple other intake manifold options....

Once we are 100% happy with the performance options available, an A/C kit will happen.

Chilicharger665 12-16-2014 04:15 PM

Can we get a solid breakdown of TOTAL cost to get this thing in the car and running? What I figure so far is:

1. $3,999 for swap kit
2. $264 for Type S oil pump
3. $1,299 for small-tube K24 header
4. $300 clutch
5. $1320 for K-Pro

So that is $7,182, with no engine, and a lot of little things I am sure I am missing. I really, really want to do this, but it seems that the costs just keep spiraling up and up. Please, if I am totally wrong, show me why.

Chilicharger665 12-16-2014 04:34 PM

I would also like to know if anyone has some personal experience with a shop doing reasonably priced rebuilds on these K-series? As in, TSE does BP builds for a pretty decent price and I don't know where to start looking for someone doing the equivalent in the Honda world. My thoughts are to buy a K24A4 or something lame like that and have it rebuilt into a decent engine. I can only get 91 octane, so it won't have crazy compression or anything like that.

KMiata 12-16-2014 05:59 PM


Originally Posted by Chilicharger665 (Post 1189901)
Can we get a solid breakdown of TOTAL cost to get this thing in the car and running? What I figure so far is:

1. $3,999 for swap kit
2. $264 for Type S oil pump
3. $1,299 for small-tube K24 header
4. $300 clutch
5. $1320 for K-Pro

So that is $7,182, with no engine, and a lot of little things I am sure I am missing. I really, really want to do this, but it seems that the costs just keep spiraling up and up. Please, if I am totally wrong, show me why.

-Kpro is $700 (plus a $200 used ECU)
-Used K24A2 engines can be had for $1000-$1200 everywhere
-Although our header is a huge value at $1299, we will also have a budget header available in 2015

Estimated total build cost just depends on how fancy you want to get, and power goals.

Here is the real question – what is the estimated cost of any other Miata build that’s going to give you 230-240whp out of a OEM reliable engine, with zero overheating issues, with replacement engines available from junkyards across the country for dirt cheap?

njn63 12-16-2014 06:29 PM


Originally Posted by Chilicharger665 (Post 1189901)
Can we get a solid breakdown of TOTAL cost to get this thing in the car and running? What I figure so far is:

1. $3,999 for swap kit
2. $264 for Type S oil pump
3. $1,299 for small-tube K24 header
4. $300 clutch
5. $1320 for K-Pro

So that is $7,182, with no engine, and a lot of little things I am sure I am missing. I really, really want to do this, but it seems that the costs just keep spiraling up and up. Please, if I am totally wrong, show me why.

My spreadsheet says ~$8,600 as the projected cost at the moment for my swap and I'm missing a few things still.

I went back and forth a few times on the "is it worth it?" question. At the end of the day, any (street legal) setup that offers this level of reliable performance will cost the same and have higher wear item costs.

As far as built engines, seems like a lot of people use these guys: http://www.team4piston.com/

emilio700 12-16-2014 06:32 PM


Originally Posted by Chilicharger665 (Post 1189904)
I would also like to know if anyone has some personal experience with a shop doing reasonably priced rebuilds on these K-series? As in, TSE does BP builds for a pretty decent price and I don't know where to start looking for someone doing the equivalent in the Honda world. My thoughts are to buy a K24A4 or something lame like that and have it rebuilt into a decent engine. I can only get 91 octane, so it won't have crazy compression or anything like that.

Junkyard K engines tend to be fairly healthy to start. Don't over rev them and there is nothing required to make them "decent".

N/A 190-240whp on pump gas, the K is cheaper and more reliable than a BP. BP only challenges below 7500rpm and below say, 170whp. Even there though, you could do one of the lower spec K engines from a junkyard for like $800 and hit 175whp, less than what a tired, used NB2 engined costs.

I think of it this way it's the most power per/wrenching hour of any current option. Only Rotrex setup (based on a JR, not KW) approaches the power/per wrenching hour. The best ratio is down with our rental formula, i.e, stock NB2 with bolt ons. That can be done for about $3000 all in and is bombproof but that only nets 140whp or so.

AndyHollis 12-16-2014 06:59 PM


Originally Posted by Chilicharger665 (Post 1189904)
I would also like to know if anyone has some personal experience with a shop doing reasonably priced rebuilds on these K-series? As in, TSE does BP builds for a pretty decent price and I don't know where to start looking for someone doing the equivalent in the Honda world. My thoughts are to buy a K24A4 or something lame like that and have it rebuilt into a decent engine. I can only get 91 octane, so it won't have crazy compression or anything like that.

The easy button, as David has mentioned, is an 06-08 TSX motor (K24A2) with reasonable mileage. These all come behind automatic transmissions so they have lived easy lives. That's an easy 230hp at the wheels with the right bolt-ons and tune.

If you want a bit more, swap in the 50-degree VTC gear from any of a variety of K-series motors, and you can increase the mid-range performance substantially. While you are in there, a drop-in cam will add 10-20hp across the board. Here's one: Drag Cartel Drop-In Camshafts - Modified Magazine Kelford 179-A is similar but a lot cheaper (cast, not billet). So now you are at 240-250 with zero work done to the bottom end.

From here, it starts getting more involved and expensive. You'll need more compression, and bigger cams with stiffer valve springs. For this approach, I like buying used Accord motors (K24A4 and K24A8) for about $300, and throwing away almost everything except the block and crank. Then add 12.5 Wiseco pistons at standard bore, and Manley rods. If the motor is in decent shape, the bearings will still be good and the bores straight. So it's a bolt-together affair. Find a used K20A2 head for about $300-450 and get a fresh valve job. Add those cams/springs and you have a 280hp motor that can reliably rev to 8500+. I just built one like that. No machining needed. FYI, the K20A2 head yields about 10-15hp over the K24A2 head with the gains starting at 6500rpm. Super reliable, super strong, runs on pump 93.

Anything higher and you are talking ported head, really big cams, big sleeved overbores, etc. My 300hp motor has all of that.

K20a.org is the place to go to find deals on used parts and even new stuff. Lots of guys start buying parts and give up on their build when their money/motivation dries up.

Oh yeah, as for shops doing rebuilds, I have a local place that does phenomenal headwork, but I use 4Piston Racing (Team4Piston.com) for pro shortblock builds and CNC head porting. ERL is another good one. Both has details on their web sites.

ctdrftna 12-16-2014 07:12 PM

This swap is an investment for sure. But for me it was about having the best possible platform . Best chassis,best engine and less cost than a v8.


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