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K series Miata swap

Old 03-25-2013, 09:51 AM
  #161  
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Moving the steering rack ~4" forward, but at the same height as original, does what for geometry?
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Old 03-25-2013, 12:22 PM
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Actually a decent thread on M.net on that:
Moving steering rack fore and aft - MX-5 Miata Forum

Short story, you get some added bumpsteer that you can probably dial out again.
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Old 03-28-2013, 02:06 AM
  #163  
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This swap isn't about cost; it's about convenience. I hope it takes off, although, it shouldn't really take off any more than SR20 swaps in a Miata took off.

The only "savings" that comes from hybrid swaps is when you retain as many Miata parts as possible. Once you need a different transmission then you need mounting solutions. Then you need PPF solutions and more. The swap the retains the most Miata parts is cheapest. Engine price has nothing to do with the cost of a conversion.

The Miatabusa, for example, has the potential since it utilizes Miata everything behind the flywheel. They've got some refinement to do with the adapter plate, but there's no shortage of engineers over there.

Front sump is a real pain in the ***. Moving the steering rack is a deal killer. But, it's possible to convert to a rear sump; just know whether your oil pan is a structural part of the engine or not.

For reference, here's my SR20 rear sump conversion oil pan so we could clear the steering rack at the factory location. ~$400 for the 74lb brick of aluminum and ~$1600 for CNC time.

The room we had to work with to keep the engine below the hood, without cutting, and above the steering rack.




The side with the relief fits over the steering rack and at the back I've got a ~6t sump.




Anyway, good luck on this project. Nothing wrong with NA power.
Attached Thumbnails K series Miata swap-3816114075_689f1f5a0c.jpg   K series Miata swap-3816926544_671cc6d5e8.jpg  
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Old 03-28-2013, 03:13 AM
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A casting tool for this could be done for less than $5k. Spit out $250 pans.
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Old 03-28-2013, 03:22 AM
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My relatively primitive understanding is that it is now practical, for low-volume parts, to eliminate the need for toolmaking by using SLA to print sacrificial positives which are then used in a conventional investment-casting process.

I wonder what the cost would be to make an oil pan using this process?
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Old 03-28-2013, 03:25 AM
  #166  
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Originally Posted by Joe Perez View Post
My relatively primitive understanding is that it is now practical, for low-volume parts, to eliminate the need for toolmaking by using SLA to print sacrificial positives which are then used in a conventional investment-casting process.

I wonder what the cost would be to make an oil pan using this process?
It's cheap and we can do it all within a 100 mile radius of our shop.
Personally, I have no interest in a K swap without retaining the OEM steering geometry.
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Old 03-28-2013, 04:25 AM
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The k24 oil pump/counter-balance shaft assembly rules out the option of a custom rear sump pan.

[IMG][/IMG]



[IMG][/IMG]


From what I see his only good options are:


1) build a dry sump system

2) move the engine back



Unfortunately, these options rule out the possibility of an inexpensive or easy swap.
Attached Thumbnails K series Miata swap-k-series-k24_built_modded_oilpump_zps12b62db8.jpg   K series Miata swap-dsc03095q_zps8d262b9d.jpg   K series Miata swap-dsc031203070660_zps9509cce4.jpg  
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Old 03-28-2013, 04:46 AM
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After looking at the k20 oil pump (no counter balance shafts) it may be possible to cut the oil pickup tube portion of the oil pump off, and build one with a bend that passes over a notch in the pan above the original rack location.

Assuming that is, that the original rack location is located behind the oil pump and not under it.
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Old 03-28-2013, 05:09 AM
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Whats the difference in oil pressure of say a power steering pump vs that? Perhaps the power steering pump can be used?
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Old 03-28-2013, 05:37 AM
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Originally Posted by triple88a View Post
Whats the difference in oil pressure of say a power steering pump vs that? Perhaps the power steering pump can be used?
Dry sump systems are what you are looking for.
The belt driven pump, all the hoses and the tank placement adds huge complexity.
Moving the engine 4" rearwards would be a less poor (a lot of fab work, but no extra maintenance).
An external oil pump for a modified wet sump, maybe (one pump, two hoses, to pickup and filter), but pickup and connection needs to be made...

Merging a Miata pan (attachment to trans) and the K20 pan, fab a pickup with connection on the side of the pan? A lot of welding and custom work.

All the hassle I've seen regarding custom oiling solutions have been around dry-sump, few(?) go tough the trouble for a wet sump (are there any external pumps that could work for a wet sump? ).
We have a pan design that we know works, why not bless the K with it

S2000 Pump/pan (no, I have not searched at all)?

Last edited by NiklasFalk; 03-28-2013 at 05:58 AM.
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Old 03-28-2013, 02:16 PM
  #171  
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the pics that crowder92 posted sums up the dilemma.

In addition, from viewing the motor in the car at all angles, I don't even think a dry sump would fit over the rack.

The K series motor sits at a 13 degree angle, and because of that, plus being a couple inches taller, the crossmember has to be modified.

We kicked around a lot of ideas, but in the end, nothing seemed very feasible, even if we wanted to spend $3000 on a dry sump setup.

I'm definitely keeping all ideas on the table for now, but we are moving forward with the original design, and can always revisit this if a realistic option presents itself.

If someone else seriously wants to take a crack at it, let me know, I'll send you an adapter plate.
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Old 03-28-2013, 04:35 PM
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I have to say i highly doubt the moving of the steering rack would be an issue on a sweet vtakk street car.

For the track it seems like all the fast guys (emillio, sav, etc.) turn their nose up at the idea. This to me says something.
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Old 03-28-2013, 05:32 PM
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Originally Posted by Fireindc View Post
I have to say i highly doubt the moving of the steering rack would be an issue on a sweet vtakk street car.

For the track it seems like all the fast guys (emillio, sav, etc.) turn their nose up at the idea. This to me says something.
Point taken. We aren't going to be the first guys running a track car with a moved rack though.

I'd like to think of Austin and I as fast track guys, and we are going for it in hopes of trying a new, fast, reliable setup. One (hopefully small) compromise for a whole lot of gain.

We can always play with positioning, but the general consensus is we may pick up some bumpsteer. I can live with that.
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Old 03-28-2013, 07:46 PM
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so make/buy bump steer adjusting tie rod end.
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Old 03-28-2013, 09:35 PM
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Originally Posted by ctdrftna View Post
so make/buy bump steer adjusting tie rod end.
The tie rods will need lengthened to reach the spindles, which will change the arc they travel relative to the arc of the suspension during bump and rebound. Using adjustable tie rods will correct some of the bump steer, but if this is a track car and larger tires are planned, the increased bump steer will be very noticeable to the driver and may make the car feel twitchy.

The relocated rack also effects Ackerman geometry, but I won't go into that because this is a track car...

magicDC2, can you post some side photos of the spindle and tie rod assembly at full lock. I have seen some instances where the ball joints, outer tie rod and inner tie rod create an over-center geometry on cars with altered steering systems.
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Old 04-01-2013, 05:34 PM
  #176  
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I'm an absolute noobie when it comes to swaps so my question may be ignorant. Would a K20a2 be easier than the K24? It seems like a nice combo for a street driven car.
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Old 04-01-2013, 07:41 PM
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they are the same motor pretty much, only bore and stroke changes, they have changes to intake manifolds and oil pumps and other misc but nothing that makes one easier than the other, k series is k series pretty much
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Old 04-01-2013, 07:43 PM
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Originally Posted by ctdrftna View Post
they are the same motor pretty much, only bore and stroke changes, they have changes to intake manifolds and oil pumps and other misc but nothing that makes one easier than the other, k series is k series pretty much
Doesnt the K20 lack the balance shafts that make the sump so deep or something?
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Old 04-01-2013, 10:15 PM
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its adds more to length than depth, look at the pics above. The top pic has no balance shaft.
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Old 04-01-2013, 10:16 PM
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Originally Posted by Leafy View Post
Doesnt the K20 lack the balance shafts that make the sump so deep or something?

The following is a Honda noob post, but.....

How is engine longevity affected by removing the balance shafts? Is their purpose to sustain high rpm longevity, or is it for consumer concerns regarding smoothness of running?



On Mazda3 MZR blocks, people have removed the balance shafts chasing the 2-3 hp is supposedly takes to spin them at peak. I had a friend that pulled them, and aside from a little rougher engine quality, it lasted many 10's of thousands of miles, with a less than kind driver. Last time I saw the car, it was still running like a top. No idea if that would overstress the harmonic balancer for track use though.
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