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Lotus in the Peak
28th - 30th June 2024

Honda K20A & CPL Twin Screw Supercharger


SCOTTJ

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Well,  Bye bye to S2 VHPD Sport 190 K-Series engine.  I loved the VHPD engine so much character, overrun, pops and bangs and rumbles though Larini exhaust but now it's time for a change...

Project is nearing completion and soon will have Honda K20A & CPL Supercharger... 4.01 Final Drive... Lightened flywheel... Upgraded clutch and a few other bits.

Build is due for compleation from early April fingers crossed just ready for decent weather :)

L4TVS - Engine 1.JPG

L4TVS - Engine 2.JPG

L4TVS - Engine 4.JPG

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Yes, fingers crossed it will be fun :)  I sold VHPD, 4-2-1, Torsen LSD for slightly more than a second hand VVC ideally it needs a refresh before installation but I needed to move it on.  It was still pulling very strong and had good compression but few niggles like slight cam cover oil leak from when head gasket was done by Guglielmi 4-5 years ago.  It's served me well, great engine apart from a bit of play around spindles on Jenvey throttle bodies and TPS sensors that constantly wore through resistive track.  Hall effect TPS fixed that in the end mounted at other end of TB's :)

I have no idea how new K20+CPL will behave.  I had a K20+JRSC S1 Exige Motorsport but that was based on Phoenix engine mounts and drive shafts.  It was all a bit of a 'Heath Robinson' build, it had a toggle switch behind driver to turn on high pressure fuel pump on/off so looking towards something more capable of delivering the power and no fear of drive shaft hub nuts working lose or engine mount ripping though rear sub-frame!

It will be interesting to see what power it makes.  The CPL Supercharger kit for K20A is relatively new.

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  • 1 month later...

I think it will be similar sound to my old JRSC in characteristics and sound.  No charge cooler required with standard level of boost.  It's slightly larger displacement than JRSC.  I can't wait to get it on the road...  

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Impressive stuff.. Are those figures at the hub or calculated at the flywheel?

My JRSC makes very similar power but needs a charge cooler and is actually being 'over driven' to make those numbers.

However you get there, these power figures make for an insanely fast car!

 

 

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I believe these are calculated at flywheel.  If you look on the CPL website/Facebook page you will see similar results for K20A performed on a different rolling road.  The Sprintex S5-335 can pump approx. 1.46 liters per rotation or 335 Litres/sec with the standard pulley. I think it is mainly due to twin screw being a little more efficient.  Yet to find out how it drives...

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I drove it back late last night from Maidstone Sports Cars!   I can only describe it as beyond BALLISTIC there is no emoticon to describe the acceleration from rest.  They have done a fantastic job on the steering, suspension, transmission, Engine and CPL Supercharger installation.  Rolling road graphs cannot describe the feel, acceleration and grip.  I plan to get it weighed this lunch time so can find out the final power to weight ratio.

It's the same RR they use for all their previous K20 & JRSC installations so should be a realistic representation of the torque/power at flywheel.

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:drive:

I clearly remember the drive back from MSC in mine after having it charge cooled and Toda A3 cams fitted. I was lost for words! I thought MSC used TDI South (they did with mine) which is a hub dyno, they used to give power at the hubs AFAIK. But your graph isn't a TDI South graph, they have their logo and other info on them.

Amazing it's producing that power when you look at the air temp of 74c. Your dyno figure will be corrected for the temp but it's still impressive. Imagine how it would be if you charge-cooled it :wink:

Is the CPL charger MSC's standard fit on SC installs now that JRSC are getting hard (if not impossible) to source?

 

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I wasn't sure who they used.  At the onset of project in November I asked Andy if they would use CPL's rolling road, as i though they would have more experience mapping CPL kit.  He just said they would use usual RR they have used for many of their K20 conversions.

Yes noticed the 74c it was the one week of summer we had in April when they mapped it.  Sods law.  Heat soak off engine can't be ideal its a serious chunk of machined alloy! I might put cooling ducts to underside given time!

I think it will become MSC's standard fit as supply of JRSC units are running out.  I believe it's the first one they've done, I saw the kit on CPL's site last August and decided to go that route.  Just a matter of timings for taking car of road for 6 months over winter and slotting that in around selling VHPD engine.

 

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Hmmm... Bit of a fatty... 836kg with approx. 10 litres of fuel on gauge... so 826kg roughly equating to 430bhp/tonne...

That’s with my butties in the boot!

 

Happy :) 

Weigh_1.JPG

Weight_2.JPG

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