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Discussion Starter · #1 · (Edited)
My wife has a 2008 Civic SI, and I love the engine, I have a CA exemption for a RWD Lotus 7 replica kit car based on 1960 smog requirements (ie. no requirements.) How can I mate it to a RWD transmission? I can get around all the FWD vs. RWD issues if I can find a transmission and bellhousing.
 

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There's been conversions with b18 civics before where the owners literally grafted a b20 CRV 4WD drive train and then made it rear wheel drive. In the time and cost that's associated with doing a k20/k24 RWD conversion you might as well just buy a new age RWD sports car.
 

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not gong to lie to ya. why not just go with an f2x out of a s2k, the motors are remarkably similar.
 

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It shouldnt be hard to have a custom bellhousing fabbed to match the K20 to a Borg Warner trans.
I researched this while debating which route to go with my rock crawler, either the conventional north-south route with a fabricated bellhousing or as I finally decided in using the complete FWD engine/trans mounted midships in a north-south cabover design.

I do know of a Suzuki Samurai with a F22c and 6speed mounted under the hood, nothing more impressive than a 80"wheelbase 4 wheel drive vehicle with 36 inch tall tires doing wheelies!

Your best bet would be a F2Xc engine and trans, far less fab work.
 

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Discussion Starter · #6 ·
The K20 has such a great power band, and the car I'm building is very low, and the F20 engine is actually very tall, I have my wife's car to use to figure out the wiring, so I'm looking for a solution. Sounds like it isn't going to be easy. I need to research reflashing the F20 ECU for better mid-range power.
 

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Although i have never done a K20 specifically I have however adapted quite a number of engines to gearboxes and it's really not so hard.

Simplistically speaking you need a piece of 1/2" aluminium plate (steel is ok but heavier of course) and drill the holes for the Honda and drill the holes for the gearbox. You will need to countersink some of the holes and use allen countersunk screws where the adaptor overlaps the box or engine. It is important to ensure that the gearbox sits central to the motor of course.

Starter motor can be a pain for the weather protection, you may have to cut that part out of the gearbox bellhousing and I have seen a few different solutions from riveted on tin covers or people just leave it as it is. Sometimes you can repositon the starter holes on the adaptor to match up to the bellhousing's starter bulge.

You should plan ahead for the clutch plate - find one for the gearbox that has the same outside diameter (or very close) to the Honda. You may have to make the clutch plate up with the box spline and the Honda outer size, many cltch reco shops can do that but life is easier if you just find the right size.

The next problem is the spigot bearing for the nose of the input shaft to be supported, I have often thrown the roller bearing away and made up a new bronze bush for the purpose.

And last is the throwout fork, many times I have used the standard fork and sometimes I have had to replace or mod the fork or bearing support or find a throwout bearing with a different height.

It's a logical step by step process and I wouldn't consider it hard with pre planning.

Also sometimes you can score with a company that makes adaptor plates and kits, if they haven't got what you want they may make it a bit cheaper for you if you supply the engine and trans as this gives them another product to sell.

 

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Hi,

I am currently adapting a K24 to a Toyota W 57 gearbox.

I am putting it in Lotus 7 replica. The chassis is Chrome molly. Target weight 550kgs , target HP is 260 on rear wheels(Don't need any more)

I have done a CAD drawing of the adapter and am just about to CNC mill it out of aluminum billet plate.

It is a relatively simple conversion so far and I will start a build thread as soon as I have been given permission as I have just joined the forum.

I am installing quad throttle bodies and running the motor on a Link G4 Storm ECU.

Mark
 

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Discussion Starter · #13 ·
Incredible, I have a toyota t-50 transmission mounted in a Locost frame with a custom drive shaft and Mazda Miata rear suspension, only lacking the transmission/engine adapter to mount a K-20 engine. And I have the coveted California SB100 exemption for bypassing smog or any other requirements for this car for 2010. I'm excited about this!
 

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I do not have a CAD drawing. I used a vary crude, simple method of aligning the T50 to the K20. I used a flat 3/8" aluminum plate (some hardened alloy of unknown origin) I had standing against the wall.

The Toyota T50 uses the bell housing the retain the front bearings of the T50 gear sets.
I cut the bell housing down so all that was left was the bearing retainer part. This also bolts to the T50 from the inside of the bell housing into the T50 case. The the T50 throw out bearing tube is also bolted to this bearing retainer plate.
Using the milling machine, I cut a tight fitting hole that the T50 throw out bearing tube just fit into (the big part, not the throw out bearing part. I bolted the throw out bearing tube to the T50 bearing retainer plate, inserted the T50 throw out bearing tube through the tight hole in the 3/8" plate.
I made a bushing (alignment sleeve) on the lathe, that was a tight fit to the T50 throw out bearing tube, and the K20 transmission input shaft bearing hole. I then used the T50 throw out bearing tube to align the three parts together. (K20 case, 3/8" plate, T50 bearing retainer). I think I had to shorten the T50 throw out tube.
The T50 throw out bearing to is now centered on the K20 throw out bearing tube.
The 3/8" plate is now able to be rotated (clocked) around the K20 clutch center line till the T50 case has the gear shift lever aligned straight up, or at what ever angle you want it to be. There may be some clearencing needed on the inside of the K20 case to clear the T50 bolts.
Several of the K20 bolt holes are straight through so the 3/8" plate can be marked and drilled to allow attaching the 3/8 plate to the K20 case. The rest of the 3/8 plate to K20 mounting holes were SWAG'd. (Scientific Wild Ass Guess).
When you are absolutely certain the engine is at the angle you want, and the T50 is at the angle you want then dill the holes throught the 3/8" plate for the T50 attachment bolts. I think I may have even used the original T50 bolts.

Does your head hurt?
I wish I had drawings.
Del Long
 

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Hi Del,

Actually it does hurt :dance:

Is there a reason you simply didn't just do an adapter plate to bolt the whole T50 bellhousing ?

Thanks

Fred
 

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Hi Guys,

I have managed to find a good quality clutch plate , pressure plate and bearing that are "off the shelf items".

I am totally amazed that this is going so well!

So after 2 weeks the state of play is : I have purchased motor , transmission and throttle bodies.I have the clutch assembly sorted , fork is std Toyota as well as the slave. I have a DXF done of the adapter plate , I have milled off the correct amount on the Bell housing and am waiting for my mate to CNC mill the plate. Once I have it together and am sure it will work I am going to make a casting pattern and cast it.

Photo's by Wednesday boys!

Mark
 

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Sorry for the lack of progress but we had the little matter of an earthquake to deal with here in Christchurch New Zealand. Unfortunately my shop and home took a hit and I have been sorting out these issues with insurance etc.

The bell housing casting pattern is underway but an ETA is not known as they took a bit hit themselves with the quake.

On the plus side I have trial fitted the motor and transmission in a frame and after I chop the sump about 2" I will have enough space to get everything nicely under the bonnet. I really don't want to mess with the Lotus 7 shape if I can.

Pics to come as soon as I have all the pieces together.

Mark
 
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