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Hi, all! First off, thanks for the awesome forum! I've lurked around a bit over the last year while I've been working on my project and have found a ton of great information from this forum already. I'm at the point in my build though that I thought it wise to sign up and ask for some help from the pros.

Like the title says, and @Gerald B posted a few days ago, I have also have a bit of a unique build. I started with a 1978 Alfa Romeo Spider and have been working a K20A3 from an automatic RSX and Getrag 250 from an E46 BMW 323i into this. Here's a photo of how she started:
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I drove and enjoyed the car with its stock 2.0 and dual carbs for quite some time but found myself constantly chasing issues on it (I know...shocker, it's an Alfa). But, as is my nature, I decided to put it under the knife. I've been documenting the build for the last couple of months on the AlfaBB forum if anyone wants to see a ton of photos.

At this time I've managed to get the engine and tranny mated up and engine bay modified to accept it. AC/PS delete with alternator relocated. KPower intake. 74mm TB. Custom header. It's not the prettiest build, but here's the ultimate goal of it; I want to get this in and running and work out the bugs on a cheap A3. Once I've had some time to shake it down I can build a proper A2 and bolt the custom bits onto it.

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I pulled the engine and transmission again the other night to clean up the engine bay and get to work on mounting all of the engine's accessories and wiring. This is how she stands tonight.
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I'm reaching out to see if folks can help point me in the right direction on the wiring side of things. I've done a few engine swaps in life but this is my first go at a fuel injected setup this new. I have complete engine and chassis harnesses as well as the matching ECU.

I'm not intimidated to cut into the factory harness to remove what's not needed, extend and re-route what is, and make things work as they should, but I expect there's already some good documentation out there that I may just not have found yet that can help point me down this road with some better clarity. I anticipate trouble with the lack of Honda transmission (i.e. speed indicators) and removal of evap circuit. I'd like to use the factory gear as much as possible to help keep things in budget. Any direction would be appreciated. Thanks in advance!
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Hi, all! First off, thanks for the awesome forum! I've lurked around a bit over the last year while I've been working on my project and have found a ton of great information from this forum already. I'm at the point in my build though that I thought it wise to sign up and ask for some help from the pros.

Like the title says, and @Gerald B posted a few days ago, I have also have a bit of a unique build. I started with a 1978 Alfa Romeo Spider and have been working a K20A3 from an automatic RSX and Getrag 250 from an E46 BMW 323i into this. Here's a photo of how she started:
View attachment 105495

I drove and enjoyed the car with its stock 2.0 and dual carbs for quite some time but found myself constantly chasing issues on it (I know...shocker, it's an Alfa). But, as is my nature, I decided to put it under the knife. I've been documenting the build for the last couple of months on the AlfaBB forum if anyone wants to see a ton of photos.

At this time I've managed to get the engine and tranny mated up and engine bay modified to accept it. AC/PS delete with alternator relocated. KPower intake. 74mm TB. Custom header. It's not the prettiest build, but here's the ultimate goal of it; I want to get this in and running and work out the bugs on a cheap A3. Once I've had some time to shake it down I can build a proper A2 and bolt the custom bits onto it.

View attachment 105496

I pulled the engine and transmission again the other night to clean up the engine bay and get to work on mounting all of the engine's accessories and wiring. This is how she stands tonight.
View attachment 105497

I'm reaching out to see if folks can help point me in the right direction on the wiring side of things. I've done a few engine swaps in life but this is my first go at a fuel injected setup this new. I have complete engine and chassis harnesses as well as the matching ECU.

I'm not intimidated to cut into the factory harness to remove what's not needed, extend and re-route what is, and make things work as they should, but I expect there's already some good documentation out there that I may just not have found yet that can help point me down this road with some better clarity. I anticipate trouble with the lack of Honda transmission (i.e. speed indicators) and removal of evap circuit. I'd like to use the factory gear as much as possible to help keep things in budget. Any direction would be appreciated. Thanks in advance!
View attachment 105498
Very cool looking project! What brand throttle body did you go with and are you using the k series sensors on it still? Besides figuring out the speed sensor and wiring your reverse sensor to work with the getrag possibly there should just be the one black /orange plug for evap by the throttle wiring that can be done away with , I just cut mine and covered the wires with the rest of the wrapping.
 

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What are you doing for a fuel pump? Is the ecu KPRO or something similar ? It will want secondary o2 and a couple other annoying things if the ecu is untouched still.
 

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getting that header built looks like it was a chore. I am really digging your build, it is awesome to see some these older Euro models getting Kseries love
 

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Nice. My mother in law had a 1.6l on doutlet dual weber carbs. It was running well and sounded awesome.
A k20a3, a K24a(3) will suit it even better. The Alfa engine never revved that high (as in OEM tune) and the extra torque will make it a very relaxing drive.
 

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Discussion Starter · #6 ·
Very cool looking project! What brand throttle body did you go with and are you using the k series sensors on it still? Besides figuring out the speed sensor and wiring your reverse sensor to work with the getrag possibly there should just be the one black /orange plug for evap by the throttle wiring that can be done away with , I just cut mine and covered the wires with the rest of the wrapping.
KBuilt,
Thanks! I’m just using an eBay generic TB. It’s a B-series clone though and has the B-series TPS with it.
The reverse sensor seems like an easy one to sort out. The speed sensor…not sure on that guy yet :)
 

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Discussion Starter · #7 ·
What are you doing for a fuel pump? Is the ecu KPRO or something similar ? It will want secondary o2 and a couple other annoying things if the ecu is untouched still.
I’m using a Jegs frame mounted fuel pump. The ECU I have is the stock from the RSX. Do you see issues with this?
Regarding the O2 sensor, I figured I’d need the primary and secondary O2 sensors and have bungs in hand to weld into my exhaust system when I build it. Am I on the right track with that move?
 

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Discussion Starter · #8 ·
getting that header built looks like it was a chore. I am really digging your build, it is awesome to see some these older Euro models getting Kseries love
Thanks, Them Witches!
The header was…well, it was my first shot at TIG welding. So never mind the fact that it looks like it does. That said, it was a ton of fun to build. I posted that process on the Alfa thread in my first post if you’re that interested (or bored). All said, I’m really pleased with how it came together. All of my primaries are within an inch
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Discussion Starter · #10 ·
Nice. My mother in law had a 1.6l on doutlet dual weber carbs. It was running well and sounded awesome.
A k20a3, a K24a(3) will suit it even better. The Alfa engine never revved that high (as in OEM tune) and the extra torque will make it a very relaxing drive.
Not gonna lie, that Alfa was a ton of fun. I don’t think I’ll miss it though…except for the sound. That engine had the most beautiful tone.
 

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KBuilt,
Thanks! I’m just using an eBay generic TB. It’s a B-series clone though and has the B-series TPS with it.
The reverse sensor seems like an easy one to sort out. The speed sensor…not sure on that guy yet :)
B series was a smart way to go , I have the same on my k24a. The B TPS is much more reliable 👍
 

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Discussion Starter · #12 ·
Can anyone help me ID what wires/plugs can be 86’d without causing issues when plugged into the factory ECU?
I know the K20 intake manifold, for example, has the runner bypass solenoid setup. This won’t be present in my build. Will eliminating or leaving these connectors disconnected cause issues starting and running?
 

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Discussion Starter · #13 ·
And here’s another question for the gurus here…I’d like to set up a temporary digital dash using a Bluetooth OBD sender and tablet. Has anyone personally done this successfully and have products they can recommend? What challenges did you hit with this setup?
 

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What a nice engine project @MarklotS with some nice DIY components and welcome to K20a.org.

...and have found a ton of great information from this forum already.
Great to read this.

BTW, if this short runner 4-1 header has around 480 mm from flange till crossing line of symmetry line of all runners at the merger you will see mainly two supporting engine speeds during the tuning of that car from header side beside the supporting engine speeds from the IM. The first are likely around 7770 rpm and 5180 rpm depending the correctness of the runner length as well as exhaust gas temperature. Once you tune it, it is likely you will find a communication exhaust gas from e.g. cylinder #1 into #3, as the lengths are short enough for this. I saw this even on 4-1 header lengths of around 650 mm at very advanced cam phases. Maybe you keep that in mind when you tune it.

If they would be a bit less then double of it, the supporting speed lines would be a bit better distributed: at 8, 4 and 3 krpm, the IM would likely support at around 6 krpm as well as around 2.5 krpm. Downside would be clearance, which could be increased by a 4-2-1 header system. Maybe when you push the button for the second round with the next K-engine (performance VTEC head, or similar) that could be an option?

I anticipate trouble with the lack of Honda transmission (i.e. speed indicators) and removal of evap circuit
A few guys use the DCT from BMW or a manual version of it. Does the Honda F20C1 gearbox (S2000 chassis) not fit in that chassis? There are adapter plates available for several gearboxes. I would ask one of the members here who have done it already to get e.g. a step file of the adapter plate to get it done at a machine shop at your place or use a solution of one of the aftermarket supporters. I don't like to advertise one specially, but check out the Miata scene, you will find tons of stuff regarding this.
 

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Discussion Starter · #18 ·
What a nice engine project @MarklotS with some nice DIY components and welcome to K20a.org.

Great to read this.

BTW, if this short runner 4-1 header has around 480 mm from flange till crossing line of symmetry line of all runners at the merger you will see mainly two supporting engine speeds during the tuning of that car from header side beside the supporting engine speeds from the IM. The first are likely around 7770 rpm and 5180 rpm depending the correctness of the runner length as well as exhaust gas temperature. Once you tune it, it is likely you will find a communication exhaust gas from e.g. cylinder #1 into #3, as the lengths are short enough for this. I saw this even on 4-1 header lengths of around 650 mm at very advanced cam phases. Maybe you keep that in mind when you tune it.

If they would be a bit less then double of it, the supporting speed lines would be a bit better distributed: at 8, 4 and 3 krpm, the IM would likely support at around 6 krpm as well as around 2.5 krpm. Downside would be clearance, which could be increased by a 4-2-1 header system. Maybe when you push the button for the second round with the next K-engine (performance VTEC head, or similar) that could be an option?

A few guys use the DCT from BMW or a manual version of it. Does the Honda F20C1 gearbox (S2000 chassis) not fit in that chassis? There are adapter plates available for several gearboxes. I would ask one of the members here who have done it already to get e.g. a step file of the adapter plate to get it done at a machine shop at your place or use a solution of one of the aftermarket supporters. I don't like to advertise one specially, but check out the Miata scene, you will find tons of stuff regarding this.
Fantastic input! Thanks so much for taking the time to weigh in here. My primaries came in at an average centerline length of 19.875" (~505mm). I'll keep those RPMs in mind though when we get to that phase. Thank you.

I'm not opposed to building another one when that day comes. It's a fun project.

The S2K gearbox does fit, but I'm pretty frugal and couldn't convince myself to spend the kind of money people were asking for one. I looked quite a bit at the KPower/KMiata offerings and picked up their intake for this project. I snagged an adapter plate and flywheel from PMC for this project. Again, I couldn't talk myself into KPower's price for their adapter and flywheel; no argument though on their quality, it's really top shelf stuff.
 

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I was just telling my Dad about your build. I have schooled him on Hondas and the fact you have a 78 Euro chassis made him want to check it out.
 
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