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K20 5th Gen Prelude Swap Guide

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Mudgey
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K20 5th Gen Prelude Swap Guide

Post by Mudgey » Mon Jun 03, 2013 10:50 am

K20 5th Gen Prelude Swap Guide

Updated: 03.06.2013

I think its about time I start sharing some of the knowledge I have gained from doing the swap, it is by no means finished so I shall be updating this thread as I go and turning it into a complete guide with pictures where possible. There are only a handful of people around the world that I know of who have completed this swap, even less have done the K20, most go with the K24 and Hasport mounts.



Engine Choice:

So if your interested and your wondering whether to go K20 or K24 then here is my take on which engine I feel is best:

K20 For:
Plenty around.
20mm less engine height = better ground clearance.
Produces less torque per hp compared to K24 & considering the weak point is usually the gearbox this means your engine can reach higher hp figures before needing a gbox upgrade.

Against:
Not as much low down torque as the k24.

K24 For:
More low down torque compared to the K20.
More power potential when tuned N/A - tbh this is more expensive than sticking a JRSC on a K20 so I don't imagine many people would go down this route in the UK, however you can't beat the sound of a ITB K24 producing north of 300hp!! If I had the money I probably would!!

Against:
Torque trails off in the top end quicker than the K20 so it feels a bit lacking up top - some people prefer mid range, others prefer top end - personally I prefer motors that pull harder up top towards the red line - the std Prelude Type S engine is a good example of this where max torque comes in 2/3rds up its rev range. If your spending money then a worked head with cams will move peak torque further up the rev range.
Due to the higher torque output you'll need a gbox upgrade sooner than the K20.
Ground clearance - with our roads and the governments obsession with speed bumps I think the K20 is better, especially if you like your car lowered - I wouldn't want my engine to sit 20mm lower than it is now!!

Assuming you have the time and space, I have found the cheapest method is to buy a complete car and break it for the bits you require, I purchased a whole supercharged CTR EP3 and was able to get a sense of what the motor was like before it was all ripped apart. Once all the parts were sold I ended up with a supercharged engine with all the parts required for the same price as I have seen just the Jackson Racing Supercharger kits going for 2nd hand.



Now I have the motor what other parts are required?

More original parts are useable than you may find with other k-swap cars which helps keep the conversion costs as low as possible.

Throttle Cable - The original throttle cable on the RHD preludes is long enough to reach perfectly to the new throttle body position, all that is required is an extended throttle body cable mounting bracket to pick up the slack in the longer length of inner cable. It is best to cable tie or mount the throttle cable along the front strut brace which keeps it out of the way of the exhaust and keeps all bends nice and gradual. Unfortunately the throttle still feels very sensitive just like the original engine and does take a little adjusting to if your not used to driving the car!

Gearcables - The original gear cables are just about long enough to fit the new gearchange position on the gearbox but only if the engine is positioned far enough back and therefore cutting the rear most front subframe is required. The gearcable bush diameters are the correct size to fit the gearbox gearchange posts. One cable is much longer than the other due to the original orientation but they work just fine. The throw on the K20 gearbox is much less than the original and once all is connected you will notice the gearchange feels just like you have fitted a short shift kit. All gears inc reverse are selectable easily with a lot of room to spare in the gate. I can confirm the gearbox is effortless to change and feels more akin to the S2000 gearchange than the original preludes.

Driveshafts - The original shafts are useable, or you are required to do is swap them around, left goes on the right and vice versa.

Radiator - You can use the original Prelude radiator, I used the following hoses to hook everything up:

3x 32mm 90's
1x 32mm 45
1x 32mm Short Straight Joiner.
1x 32mm 135 degree Bend (to allow the return hose to go underneath the intake pipe).

Radiator Fans - The originals are very thick & may work but I have never tried. I used a couple of ebay special slimline fans, the old addage you get what you pay for applys here, they are very weak and there is no guarantee how long they will last but they do keep the engine temp in check.

Rad Fan Switch - The Civic has the rad fan switch on the outlet side of the radiator, the prelude has it located on the engine somewhere, that means with the K20 installed you have no position for the rad fan switch, here are a couple places you could install it:

1. Inline housing installed in the water line between the water pump and bottom of the radiator.
2. Use a K-Tuned billet thermostat housing, this has the correct threaded hole for the rad fan switch.
3. Weld a bung onto an aftermarket aluminium prelude radiator.




More to follow...

thusee
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Post by thusee » Wed Jul 29, 2015 6:33 pm

I know this is old but does anyone know if there was any update to this on a different page or forum?

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NafemanNathan
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Post by NafemanNathan » Thu Jul 30, 2015 8:19 am

Unfortunately soon after completetion Mudgey broke his car, but you can follow all of it here if you haven't already...

http://www.ludegeneration.co.uk/profile ... t5201.html

thusee
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Post by thusee » Thu Jul 30, 2015 4:38 pm

Awesome thanks! After doing all the restore on my car i have nothing to do now haha so i'm looking for something.

s2k cluster swap and K swap idea's......

This thread was a good start and then it died after the first post... :(

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RattyMcClelland
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Post by RattyMcClelland » Thu Jul 30, 2015 5:14 pm

I know of a company working on k20 engine mounts for Preludes. Watch this space. Nothing to do with me and no I can't say anymore.
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thusee
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Post by thusee » Thu Jul 30, 2015 6:27 pm

haha, was just curious and how much work would be involved.

LudeDudeBB6
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Re: K20 5th Gen Prelude Swap Guide

Post by LudeDudeBB6 » Mon Jan 18, 2016 2:07 am

Any word ratty on k swap into lude?

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RattyMcClelland
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Post by RattyMcClelland » Mon Jan 18, 2016 10:31 am

Ask Hond-r.
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