Caterham Honda k20?

[JeffC]

Hi all, In previous years I have owned quite a few Caterhams and selling my current Honda race car with plans to return to the fold, I have previously owned an R500/R300/R400 and R600 and the sweet spot for me for track use was the R400 duratec. so I am either looking for one if anyone is thinking of selling however and this is the reason for the post I also quite fancy building one with a Honda K20 engine so would also be interested in a project 7, but the k20 conversion doesn't seem to be a well trodden path in a 7 although i do seem to recall there was one kicking about a few years ago, would be helpful to get some info on what the conversion involves. I currently have an S1 Elise that I have fitted a k24/k20 frank to and my CRX race car has a 285bhp k20 fitted and If I cant sell complete I will likely break it so will have the engine /ITBS and management hence building a Caterham with this engine appeals.

[cptsideways]

Am I right in thinking the K20 is a very tall engine, much taller than a Duratec for example & they simply don't fit well?

[Batwing 7]

If they can do it in a Fraser (there are a couple) here in NZ, then it can be done in a Caterham!

https://www.lotus7.club/forum/chitchat/introductio...

[griffchris]

PM sent Jeff
Chris

[mickrick]

It's been done, but as already mentioned, they are a bit tall.
Don't some of the Honda engines also rotate a different way?

[JeffC]

griffchris said:

PM sent Jeff
Chris

my pm wont work as its on my old email address and I cant work out how to change it, I have sent you one though with my details.

cheers.

[JeffC]

mickrick said:

It's been done, but as already mentioned, they are a bit tall.
Don't some of the Honda engines also rotate a different way?

no the k is fine its the older B series that were backside first.

[gixermark]

Sevens are hard to stay away from Jeff! Be interesting to see what you build!! Your white one was just about perfect!

I've recently bought a k series super light, sharp little thing!

[JeffC]

gixermark said:

Sevens are hard to stay away from Jeff! Be interesting to see what you build!! Your white one was just about perfect!

I've recently bought a k series super light, sharp little thing!

yeh cheers I spent some time on that car !

[e21jason]

Already been done

https://www.pistonheads.com/gassing/topic.asp?h=0&...

And the bits are available and I was thinking the same thing as I spanner on a DC5 endurance car and have an atom so plenty of K20 bits around

J

[JeffC]

e21jason said:

Already been done

https://www.pistonheads.com/gassing/topic.asp?h=0&...

And the bits are available and I was thinking the same thing as I spanner on a DC5 endurance car and have an atom so plenty of K20 bits around

J

thanks for that and very handy that conversion parts are available I was expecting to have to make everything .

[k20erham]

Hi I've got one, the photos in the link of the Arrows rods are of mine with the Sadev box, the sound that the Hondas make is worth it alone, very addictive.

[k20erham]

https://www.youtube.com/watch?v=CPYeDWW-pSY
The 1st mapping event which revealed the exhaust was not good, a chat with a very respected fabricator resulted in the correct set up.

[JeffC]

JeffC said:

Hi all, In previous years I have owned quite a few Caterhams and selling my current Honda race car with plans to return to the fold, I have previously owned an R500/R300/R400 and R600 and the sweet spot for me for track use was the R400 duratec. so I am either looking for one if anyone is thinking of selling however and this is the reason for the post I also quite fancy building one with a Honda K20 engine so would also be interested in a project 7, but the k20 conversion doesn't seem to be a well trodden path in a 7 although i do seem to recall there was one kicking about a few years ago, would be helpful to get some info on what the conversion involves. I currently have an S1 Elise that I have fitted a k24/k20 frank to and my CRX race car has a 285bhp k20 fitted and If I cant sell complete I will likely break it so will have the engine /ITBS and management hence building a Caterham with this engine appeals.

so this did happen over winter.

bought this

|https://thumbsnap.com/k2cppxOI[/url]


once I got started it all became pretty obvious why the K20 isn't a common engine swap in an S3,conversion parts were not readily available so pretty much everything has to be made, the engine is massively taller and with the engine sat in there was around 25mm of ground clearance even then the bonnet was struggling to shut , bell housing too wide for the tunnel and everything down the left hand side too tight, mine is a metric chassis think the previous cars that have been built were done on imperial no idea if that makes it easier or harder but this has been a chew from the start to do certainly not a cost effective or straight forward swap.
as above ground clearance is the biggest issue, I ended up sourcing a dry sump system with a pan that is only 40mm deep this reduced the height on the tall side by 120mm the standard Honda sump is massive due to the internal oil pump , I retained the standard Honda flywheel, got a spacer machined to suit my adapter bell housing this allowed me to set the engine further back in the chassis to improve clearance and I also managed to slightly improve on the ground clearance of the original sigma bell housing.
I really didn't fancy using after market solutions to delete the components on the left side of the engine so to keep things reliable I managed to retain all the oem water pump housing/ alternator and fabricate plates for the dry sump pump its all tight and will be an ar*e if i need to change them but its in and does clear .

[url]

|https://thumbsnap.com/iRl30Ehs[/url]

|https://thumbsnap.com/0kMt9Ujx[/url]

Anyway just thought I would update this, Its in and running just need to get an exhaust system made this week then hopefully will get a test drive.


[url]

Edited by JeffC on Saturday 14th March 08:02

[braddo]

Awesome work

So the bellhousing is where the least ground clearance is - is that normal for the sigma/duratec cars? Or have you had to mount the gearbox lower (or is the bellhousing bigger for the K20)?

[JeffC]

braddo said:

Awesome work

So the bellhousing is where the least ground clearance is - is that normal for the sigma/duratec cars? Or have you had to mount the gearbox lower (or is the bellhousing bigger for the K20)?

bell housing is higher up than the original Ford engine, think my lowest point is the lowered floors.

[k20erham]

Hi,

Been there done it, will fantastic car when you have it done.

The K20 is very sensitive to the exhaust, especially the manifold, get it done by someone who has made them for the K20, I eventually went to BTB exhausts, or speak with Terry Bourne, it will fail on track day noise if you don't get it right, the ITB's are a delight to hear!

Which box are you running? and what ratio diff? what ecu? as th engine will normally stand the Vtec point lowering, I'm not sure about the new Hondata but the old one did not like ITB's, WOT was Ok but partial throttle and in the wet it was a real handful even on track, went standalone in the end.

When you dry sumped did you block off the oil gallery in the bottom of the block?

[JeffC]

k20erham said:

Hi,

Been there done it, will fantastic car when you have it done.

The K20 is very sensitive to the exhaust, especially the manifold, get it done by someone who has made them for the K20, I eventually went to BTB exhausts, or speak with Terry Bourne, it will fail on track day noise if you don't get it right, the ITB's are a delight to hear!

Which box are you running? and what ratio diff? what ecu? as th engine will normally stand the Vtec point lowering, I'm not sure about the new Hondata but the old one did not like ITB's, WOT was Ok but partial throttle and in the wet it was a real handful even on track, went standalone in the end.

When you dry sumped did you block off the oil gallery in the bottom of the block?

Manifold made by a very well respected manufacturer and familiar with the K20 engine 2" headers into a 2 3/4 system, had first road test today and its quiet, unlike the itbs will have to source an airbox for trackwork

Cat 6 speed box for now may end up Sadev. Diff I have not checked but whatever is fitted to the Sigmax cars as thats what it set off as, I have fitted the bigger Sadev prop.

its on Hondata Ecu not ideal for partial throttle due to the map sensor issue, will see how that plays out on track, I run the engine in the Crx for 5 years on the same set up and I could get by.

yes blocked off the hole in the block.


first road test today and its pretty impressive couple of things to sort but happy will see if I can post a link from Fb.

Edited by JeffC on Monday 23 March 22:21