Turbo K20A2 build thread - LotusTalk - The Lotus Cars Community

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post #1 of 41 (permalink) Old 01-03-2017, 05:13 PM Thread Starter
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Turbo K20A2 build thread

Happy 2017! Well, it's time for a new project and for my car to start the 4th of it's 9 lives. It's turbo K20 time!

Here's some brief background:

1) I got my car, and it was awesome
2)
3)

The culprit was identified as a fragged oil pump. 8500rpm + 400hp + time on those sintered gears and all hell broke loose. Just to be clear: this was not a failure of the BOE REV400 kit. This was a Toyota part failure, which was likely exacerbated by the power of the car. If anyone is going to do more power than a BOE REV300 kit and start building a 2ZZ motor, please make sure you address this. I _really_ wish it had been taken care of on mine. I'd be happy to still be driving a 2ZZ motor.

After weighing my options for a motor replacement, I decided I did not want to go in for the time and expense of another built motor. This is supposed to be a street/track fun car for me, not a world-record beater, and I wanted to avoid the expense and one-off nature of a built motor. If (when?) I blow the next motor in the car, I'd like to just pull it and replace it with a core, so I had a decision to make: stay with 2ZZ and detune, or move to something else. I made the decision to go with a Honda K20A2.

I'm using a Honda K20A2 from a 2002 Acura RSX-S. I was able to source a complete motor, transmission, wiring, and ECU setup from a running, non-molested car that was going under the knife for a different motor swap. Anticipating putting down some serious power, I'm going to upgrade the transmission by adding a Wavetrac LSD, and a slower final drive ratio from Gear-X. To hold the power I'm using a Competition Clutch Stage 5 sprung clutch and their matching 8lb Ultra Lightweight Flywheel.

Fueling is going to be setup for flex-fuel, tuned for 93 pump and E85. I've sourced some ID2000-equivalent Bosch injectors built and flowed by a nearby speed shop. I've never had a flexfuel car before and am excited for the possibilities of E85 blends in the turbo. The power numbers people are making on stock K20 blocks with this setup are insane, over 600whp. I will not be shooting for something quite that high.

For motor and transmission mounts, I've sourced the Innovative Mounts K20 engine mounts, as well as the transmission axles and shifter linkages.

For pure fun factor and "while you're there", I've also added in an AliTech shifter in black and silver. I can't wait to use this thing!

Much of the above information I've already posted publicly in a couple different threads, but since the motor setup is underway I thought it would be useful to start putting all of this in 1 place for everyone to see, and make it easier and more succinct to add updates as it goes along.



Please feel free to comment, give suggestions, add critiques, ask questions, or whatever! I want to document the blood and guts of a Honda swap, as there aren't too many done in the US.






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post #2 of 41 (permalink) Old 01-03-2017, 05:23 PM Thread Starter
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Project Name: Professor Chaos

Since this was at least a little (OK, a lot!) inspired by LT forum user @Butters , this car is officially going to be called Professor Chaos!

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post #3 of 41 (permalink) Old 01-03-2017, 05:24 PM Thread Starter
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Air Conditioning

Always a 'hot' topic of conversation on swaps is air conditioning. I am going to attempt to retain full A/C and factory controls, even improving it in the process.

The K series A/C compressor dwarfs the 2ZZ one. The 2ZZ has the smallest compressor I've ever seen. I've read from other K swaps that if you try to retain the K compressor, you run into clearance issues with the firewall. As a result, I've asked the shop that is going to do the final assembly to plan to fabricate a bracket to mount the 2ZZ's compressor to the K block. I'm hoping this doesn't present any other headaches.



Also in the "while you're in there" department, I decided to disassemble the front end and tackle the HVAC resistor mod. This is a huge PITA project, but unfortunately necessary. Since I had evacuated the system to pull the 2ZZ engine, I saw it as "now or never" from an effort standpoint. If you need to do so, LT user rob13572468's thread on the DIY blower resistor is a must-read. Also, make sure to drill the pan drainage holes while you're in there. (According to the Lotus TSB).



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post #4 of 41 (permalink) Old 01-03-2017, 05:26 PM
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You should probably ask for advice/feedback from dstevens.

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post #5 of 41 (permalink) Old 01-03-2017, 05:28 PM Thread Starter
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AliTech Shifter

This also isn't directly related to the swap, but the AliTech shifter setup is so well spoken of, I had to jump on it myself. In she goes!




Richard and the AliTech team were great to work with. I don't love the 2-step order process, but it's part of their business to ensure they only produce exactly what the customer wants, and they have to be pre-paid. It is also nice that the shifter can work with reverse lockout configurations for left side (like 2ZZ) and right side (like K20) with only changing 1 small part. I am really looking forward to driving this!
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post #6 of 41 (permalink) Old 01-03-2017, 05:32 PM Thread Starter
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As of now, Jan 2017, I have completed the motor teardown and the car is now in the hands of a local Honda build / tune shop. I'll hold back on those details for now, but I've got great hopes and I've seen some other cars from this shop perform well.

@dstevens , per San, any other advice you can offer would be great.
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post #7 of 41 (permalink) Old 01-04-2017, 03:02 PM
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Hey Reach, Quick question. I notice your front oil coolers are still in place and on another thread you had a rear mounted oil cooler. Were they all in series? Or were the front ones never removed when the rear one was installed?


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post #8 of 41 (permalink) Old 01-04-2017, 04:22 PM
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Awesome, I can't wait for more updates!
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post #9 of 41 (permalink) Old 01-04-2017, 04:51 PM
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Nice! I'm in the process of pulling my engine for a turbo K series as well. I've been leaning toward a k24a2 (similar head to type-s but with 2.4 liters), but have also considered going straight k20a2. Is this something you'd considered before pulling the trigger on the k20?
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post #10 of 41 (permalink) Old 01-04-2017, 05:01 PM Thread Starter
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Quote:
Originally Posted by breeze91 View Post
Hey Reach, Quick question. I notice your front oil coolers are still in place and on another thread you had a rear mounted oil cooler. Were they all in series? Or were the front ones never removed when the rear one was installed?
In the previous setup my twin oil coolers had actually been converted to water coolers. I thought it was a bit overkill. I have deleted them entirely at this point, but I kept the hosing in the panels in case I end up needing more water cooling for the charge cooler in the new setup.

I'm hoping I can keep them out, and if so I'll fab those air ducts directly to the front rotors for some great on-track brake cooling.

Quote:
Originally Posted by Ob917 View Post
Awesome, I can't wait for more updates!


Quote:
Originally Posted by O0oDC View Post
Nice! I'm in the process of pulling my engine for a turbo K series as well. I've been leaning toward a k24a2 (similar head to type-s but with 2.4 liters), but have also considered going straight k20a2. Is this something you'd considered before pulling the trigger on the k20?
I actually had a K24 in another car. It produces more torque than the K20 but is rev limited by comparison (stock: 7500 K24 vs 8500 K20), and produces a 'peakier' power curve. I decided to go with the smaller displacement for the higher revving motor, more linear power band, and overall build reliability. There are a lot of K20's making good power out there, and the built K24's are using a LOT of K20 swapped parts, like oil pumps, heads, vtc gears, etc. Going back to what I'm looking for: stock engine blocks (I don't want to keep rebuilding engines), and no oil pump issues!!! Any small power difference stock is going to be more than made up for with the turbo.
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post #11 of 41 (permalink) Old 01-05-2017, 02:12 AM
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Great stuff. I will be keeping an eye on this as I plan to do a K Swap. I'm going to drive it this year and install it over next winter.
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post #12 of 41 (permalink) Old 01-05-2017, 07:25 AM
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Maybe the k20 swap interest in the U.S. Is growing? I hope so, it seems like a no brainier to me considering the improvements in the engines and the awesome tranny that comes with that engine. Plus the tuning potential for people who would rather stay NA. Seems pretty popular in Europe.
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post #13 of 41 (permalink) Old 01-05-2017, 08:52 AM
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I currently have a twin scroll GT35R powered K24A2 in my car (not a Lotus, but similar in that it's a MR layout).

Some notes from various posts above:
1. Buy stronger gearsets for your gearbox. I sheared 4th on mine at only 8psi (400whp/340tq), granted a K20 is going to make less torque, but it is something to plan for:


2. K24A2 is a better motor to use if going turbo, since it has piston squirters and has more potential. The best combo is the K24A2 block with the K20A2 head

3. The parts you should use on a K24 from a K20, is a pinned 50' VTC gear (pinned so it does max 45') and the oil pump

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post #14 of 41 (permalink) Old 01-05-2017, 02:13 PM
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Man I'm Jealous!

I am not bored with my power, but I would love to be actively engaged in a next level build like that. Someday!

I look forward to following this!
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post #15 of 41 (permalink) Old 01-05-2017, 03:43 PM Thread Starter
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I dropped by the shop today, and the engine was mounted up! Loving the progress. It looks like they're as excited about this as I am.






One challenge is even after custom bracketing the A/C compressor to the engine, there is zero room for the fittings. I'm going to either need some special machined 90-degree A/C fittings or... something else, I don't know. There isn't any room in this config, and right behind this part of the firewall is the gas tank I believe.




Here's a short video:
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post #16 of 41 (permalink) Old 01-05-2017, 03:46 PM
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Hey, @Reach , glad to see you're going through with this. You're gonna have a blast with this beast. As a reminder, please remember to order a set of MTech shift springs (go for the race set), otherwise the cross-gate action of your shifter will suffer. Actually, now that I've typed that, I do not know how much the AliTech shifter remedies that situation. Maybe if the shifter feels fine as is without the MTech springs it'll be one less part to replace. But if it ends up feeling a bit loose then you have a simple solution.

Rock on!

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post #17 of 41 (permalink) Old 01-05-2017, 04:29 PM Thread Starter
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Already have the MTech springs in there, took that note from our previous conversation.
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post #18 of 41 (permalink) Old 01-05-2017, 04:30 PM
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Carry on, then!
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2006 LOTUS EXIGE (ASPEN WHITE) Honda K24A2 + MPx90 supercharger. 322whp/271lb-ft @13psi. Build thread here.
1992 ACURA NSX (BERLINA BLACK) Quintessential 90's supercar.
2007 SUZUKI SV650 Track bike.
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post #19 of 41 (permalink) Old 01-06-2017, 06:07 AM Thread Starter
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Current ideas for fixing the A/C Compressor clearance issues include:

1) Rotate the compressor via a different bracket design
2) Move the compressor to the top where the P/S pulley goes on a K20 car, where I currently have an idler pulley
3) Ditch the mechanical and go with an electric A/C compressor, perhaps from Nissan Leaf or Toyota Prius

Not sure how it will play out yet. I'll keep it updated.
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post #20 of 41 (permalink) Old 01-06-2017, 07:24 AM
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Quote:
Originally Posted by Reach View Post
One challenge is even after custom bracketing the A/C compressor to the engine, there is zero room for the fittings. I'm going to either need some special machined 90-degree A/C fittings or... something else, I don't know. There isn't any room in this config, and right behind this part of the firewall is the gas tank I believe.
Can you thread a fitting into the compressor or is there no room for even a fitting?

Hard to tell in the photo you provided.

Also, how are the shift cables routed? Do they go under the gearbox?

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- '07 Grey, 1/220 in the US. Only grey in the world that is probably yellow, because color-blindedness.
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