2003 Civic 4dr K20a3 turbo **Build Thread**

[BongoBennie]

Welcome to my build thread.

Car
--2003 Civic Hybrid
Engine
--block; K20a2
--head; K20a3 (11.7:1CR)
--ARP head studs
--Intake manifold; K24a4
--Turbo; Garrett GT2554r
--Intercooler; Frozenboost air to water
Transmission
--Accord 5 speed gear set in EP3 case
----1st: 3.266
----2nd: 1.769
----3rd: 1.147
----4th: 0.872
----5th: 0.659
------FD 4.388
--OEM LSD
--OEM TypeS Flywheel
--Exedy Stage 1 clutch

GOAL, to build the ultimate commuter for my personal commute, 26 miles each way in the Vegas valley, 90% freeway and 90% @75mph +-. the other 10% is very aggressive city driving which is not conducive to getting good mileage and will do what I can for advantage (LSD, tire choice, etc). I will also have 1400 watts of audio to keep me sane.
Keep in mind there are days when I will in fact hypermile and I will definitely be doing so with this car.... sometimes, and sometime I will be hauling ass literally trying to see how fast I can get to work while still looking to see what kind of milage I'm getting regardless. I will be keeping a detailed spreadsheet to see how things are working and will even take it to the drag strip just to see what it will do.

It's obvious I'm not going to be improving the MPG of the Civic Hybrid so why Ecomodder?

This is more about the idea of having a muscular car for a commuter. One that is capable of daily fun while getting somewhat decent mileage, whatever that even means. While K swapping a 7th gen civic is nothing new, the way I'm going about it seems to be a first.

ENGINE
K series has to be one of thee most popular of any manufacturer to be tuned from parts on the shelf to hours on the dyno. That being said when I bring this list of parts up on the general K20 forums all I get is negative comments as guys feel its a waste since I can get the same power from other engines with half the money and effort not realising while HP is important it's not a race car in the least. I feel I will get the best help here on Ecomodder so that's why I'm here.

K20. Head is a3 which is the most eco version of the K head, same cam profile as K24a4, same intake manifold gasket as the K20a2, VTC is 50° same as K20a2. Valves are same as a2 but springs are lighter(single). Where this head is unique is the combustion chamber has quench pads which adds .7 to the compression ratio of what ever engine its attached to, also the exhaust ports themselves are a bit smaller compared to all other K heads which are the same.
The A2 and A3 bare blocks are the same, the basic differences are the following: The pistons 11:1 (11.7:1), Oil pump is high volume, piston oil squirters, stronger rods, counterweighted crank, aluminum oil pan.

The turbo..... just a note here, I am under no illusion that the turbo is helping me get better mileage, having a small turbo gives me quick access to power without needing to rev high to get it... The Garrett GT2554r is the smallest ball bearing turbo available, should be good for about 240HP to the wheels, again in the race crowd, a huge waste of money when it comes to HP to $$ ratio and why I'm here.

Not everyone that thinks I'm crazy though is being unhelpful, I have a great tuner that finds my build very interesting (he recommended the ARP studs). From a tuners prospective he feels the engine could easily handle 300HP with a bigger turbo at 11.7CR and 91 octane (hundreds of Kseries dyno hrs experience) With a somewhat small exhaust and lean burn tuning, I myself am very curious what a setup like this can muster up.

Transmission
Pretty simple, the Accord 5 speed comes with a wide spread perfect for this type of build, Installed these gears and the LSD from the 06 Civic Si into an 04 Si case, interesting note the Accord trans main and second shaft have slightly smaller diameters (lighter) than RSX/Civic/TXS counterparts I assume because this would be for economy reasons? Axles/hubs will be the smaller 32mm vs 36mm which is the go to for this kind of swap (base instead of type s)

Unless anyone asks I won't go into details on how to actually complete the swap however I will say this. I am swapping the Hybrid 4dr (ES9 chassis) which besides the obvious IMA stuff has a few interesting differences compared to the standard D17 4dr (ES1/ES2 chassis). First the hybrid engine unlike the D17 has a clockwise spinning engine so i sits on the same side as the Kseries, when you swap the subframe you can use all OEM RSX motor and trans mounts without the need of any type of mount conversion kits, EP3 radiator/condenser also swap. Two brake lines from master cylinder to ABS pump have sensors for the hybrid braking system (they are in the way), the corresponding RSX lines are a direct swap.

Other stuff

ECU will be Kpro V4 with boost by gear as well as an E85 sensor
5 lug swap RSX base front brakes/hubs, rear disc
Wheels are from 06 Civic Hybrid
Suspension is Koni Yellow and will be ordering Ground Control coilover kit spring rate TBT


I had planned on posting this when the car was done but at the same time I have a few questions that I want to put in front of the clan so I figured a build thread was a good idea. I will ask those in future posts.

Some may have heard me talk about this idea in different threads, the engine was destined to go into my Insight but that car just wasn't meeting my needs.... to rare, and not really a daily driver no matter how I slice it. Civic to me is so common that if I were to mess up the car I can always pull the parts for something else and the car itself is dime a dozen... compared to the Insight which is like trying to make a daily driver out a Delorean, not very practical.

[BongoBennie]

One of the first things I'd like to ask opinion on is tires.... size and type.

205/55/15 23.9" diameter would be the wise choice if performance is key, many have mounted this size and several decent summer tires are available, I like the Yokohama Fleva based on past experience with the brand.

195/65/15 25" however a great look and for economic-ish purposes a better choice as well, performance wise there isn't much. the two that come up are the Dunlop SP SPORT 5000 and the Goodyear Eagle Sport All-Season (also available in 195/60/15//24.2"dia)

Think I'll notice a huge difference in performance of any kind with either type of tire? Keep in mind drag style launches are not important.

[iikhod]

Interesting project
Do you have any plans regarding suspension and brakes? Or possible weight reduction?

[BongoBennie]

Originally Posted by iikhod

Interesting project
Do you have any plans regarding suspension and brakes? Or possible weight reduction?

Thanks, other than Koni Yellows and GC (Eibach) springs, I will have RSX rear sway bar (thicker), 4dr front sway is actually thicker than RSX and a common upgrade, it will remain. All bushings will remain rubber and most will be Moog, brakes will all be OEM RSX base including master cylinder/prop valve. All IMA will be removed and some 75lbs of audio will be added, give and take. When it runs I'll weigh it. All interior will remain with exception of the trunk which will be left mostly bare. With exception of the wheels which will look similar to stock, the car will hopefully look like the picture, stock. I probably won't even wash it much. Under hood will be absolutely no frills. 12V battery in the back, 3 orange cables will be used as the positive cable. I have most of the car stripped now and like an Insight the car is built very light weight minded, with exception of front seats, most of interior is pretty light.

[Ecky]

This is fantastic! I hadn't considered that all of the accessories would be on the correct side of the car from the hybrid's use of an L series engine.

My biggest beef with the HCH1 was the steering feel. I'm not sure if all of them are this way, but the one I owned and other I've driven had very heavy EPS. They were quiet and comfortable cars though.

Tires: I expect the two biggest differences you'll see are availability of tires, and gearing. The width difference probably won't have much real impact on traction or fuel economy. The taller tires will net you slightly better economy and slightly worse acceleration. I have 185's in the front of my Insight and they're not particularly sticky tires - a ~400 treadwear all season - and I don't have traction issues with a K24 now that they've broken in.

Take this with a grain of salt as I'm no engine tuner, but I'm a bit skeptical of such a high CR with a large-ish turbo like that. With the ~1bar of boost you'll need to hit 300HP, you're going to be pulling a *lot* of timing to keep from knocking on pump gas. Sure, it can be made to work with enough timing pulled, but timing is efficiency. Pulling timing flushes power out the exhaust unused as heat to keep cylinder pressures down, and getting timing perfect is probably your best tool for good fuel economy. I'm sure the 11.7:1 will net another 1-3% fuel economy at part throttle but you may find your tune to be on a knife-edge and will have to be very conservative with ignition timing, netting less power and economy (while under boost) than had you gone with a lower CR.

Anyhow, subscribed.

[BongoBennie]

I have a 5 psi spring in the wastegate so when driving with 91 octane I will be driving with boost on low. Reality is the best thing I can do for economy would be leave the turbo off the car so to that point most of the time I will be driving with no boost. 91 octane is also the first stage of the build. after its running and I have a solid baseline I will tune for E85 and more power the I will be adding fuel capacity to the car and eventually I want to run an entire second fuel system (bi fuel). I also have interests in CNG but still unsure on that direction. Both E85 and CNG are close to work.

https://www.hondata.com/?_route_=injector-driver

this is why the high compression ratio, the idea was to run the highest I could get away with on 91 and when driving on gasoline I will need to be mindful to make it work.

also keep in mind my tuner is not very involved in my decision making, he's mostly there to make sure I dont blow things up and is the local guy with the dyno/kpro guru. Funny thing is he had no idea you could bolt the A3 head on the A2 nor would he ever try

Also I love hearing about the luxury quality of the car since I bought it not running. It's really what I want.

[Piotrsko]

Cool project, if you can get efficiencies as promised from the engine.

Plans for aero when you are putting in heavy traffic on the superslab?

CNG solves most of the engine problems, especially if you dont bi-fuel it.

[BongoBennie]

Originally Posted by Piotrsko

Cool project, if you can get efficiencies as promised from the engine.

Plans for aero when you are putting in heavy traffic on the superslab?

CNG solves most of the engine problems, especially if you dont bi-fuel it.

Thanks.... As far as aero goes not much other than sticking to stock parts including plastic underneath. I also have the flat face 06 Civic Hybrid wheels going on if that counts as aero.

This is a good time to talk about fuel and the future of the car. The 91 octane is the base because that is what's commonly available. The idea was to build an engine that could run on alternative fuels and for and ICE engine it's E85 and CNG.... but the second stage will be E85. Once I get that down well I want develop the bi-fuel maybe even dropping to 89 or 87 and E85. Then if THAT works I would consider CNG as a base and E85 as a performance fuel, the idea is that unlike the normal driver where speeding cost you more of the same stuff, I will be using more of the stuff that is even more 'precious' in turn slowing me down. It's all a game to me. It really is a lot to unpack here in the first few threads but definitely excited to learn a bunch.

[Piotrsko]

In my experiences, CNG would be the preferred primary fuel, although more costly and rare. Many more things are possible since it tends to not knock, tolerates lean burn, and not pollute the engne oil. We were getting 300K miles on our vans 20K between oil changes before the mechanics got paranoid about the main bearings which turned out to no be wearing much at all, so perhaps 500k between overhaul.

The downside was only about 125 miles range with two 25 gallon tanks at 3K psi, less in winter when they added air to keep pressure up. I had to refuel 3 times a day in winter

[BongoBennie]

Originally Posted by Piotrsko

In my experiences, CNG would be the preferred primary fuel, although more costly and rare. Many more things are possible since it tends to not knock, tolerates lean burn, and not pollute the engne oil. We were getting 300K miles on our vans 20K between oil changes before the mechanics got paranoid about the main bearings which turned out to no be wearing much at all, so perhaps 500k between overhaul.

The downside was only about 125 miles range with two 25 gallon tanks at 3K psi, less in winter when they added air to keep pressure up. I had to refuel 3 times a day in winter

In all honesty I would love to head straight into CNG, in my world I have one pump, its at the airport which is on the commute homebound and very reliable but it's a bit more than gas. I would also be filling up every day. I AM curious about home refueling, I've done done google research over the past couple of years with little results. The "Phill" that was sold with the Civic GX seemed to have disappeared but I would LOVE to have one or something like it. If I lived in Utah it would be game on.