BP turbo vs K20 NA
 

I have been kicking around the idea of doing a K series Honda swap, since it seems that the latest thing to do is the F20c in a miata. I did some research on the K20/24 and it seems like you can make a lot of HP in them, but the torque sucks. I wanted to get the K series experience, so I went over to my honda guru friend's house yesterday and drove his 4 door Civic Si. He has an Injen intake, a full header back exhaust, not sure what brand, but the primaries are huge. He also tunes with K-Pro. I drove it and was really disappointed. I asked him how much power he thinks it makes and what it weighs. He said a little over 2700 lbs he'd guess, and he'd also guess 210whp. I asked how much torque? He goes, "like nothing, I don't know, but not much at all." The car was OK considering it was a FWD 4 door car, but I really expected a lot more out of it. It was also loud, like big time Ricer Boy loud, which I didn't like at all.
Then I left my friend drive my car. He was shocked how close the shifter throws were, and he said it felt like he had to shift a lot. We got on the highway, took the next exit, then got back on going the other way we came. I told him after the traffic clears, pull out in 1st and stand it to the floor. He did and it spun all of 1st gear, he slammed 2nd and it spun 1/2 way through that gear, slammed 3rd gear, then 4th, then we're at the next exit.
Now I have pro's and con's.

K20 pros:
Lighter than my BP
The fuel rail isn't a bitch to get to, in fact, everything looks easy to get to
The harness looks simpler
Don't need a custom ECU for tuning
Looks like local craigslist is littered with them, and cheap

K20 cons:
Aside from the lack of torque, I can't really find anything to complain about.

My car pro's:
It makes decent power and very good torque
Simple setup, everything fit's properly
My exhaust sounds really good, no ricer boy at all

My car cons:
The turbo spools way to fast
You have to use an aftermarket or custom ECU to tune it
The only way to make good power on a BP without dropping thousands is FI
My injector rail sucks to get to

What do I do? Rebuild my oil burner of an engine and put a bigger turbo on? Research building a K series motor that makes the power and torque I want?
Is a 4 cylinder running NA that makes about 225whp/207wtq too much to ask?

Why would you even consider this? What a waste of time.

K swap it

K20 then turbo?

If it "ain't broke", don't fix it. The Honda motor is exponentially better than the Mazda engine, but that's going to be a shit-ton of work and not much gain. If you didn't already have the turbo stuff this would be a different story.

GL with the FWD to RWD conversion part, but for power like you are looking for the K24A2 is the motor you would want. It's from the TSX. I'm sure you could easily get the power you are looking for out of that motor with pistons and cams. I'm 100% certain of it actually. I'm pretty sure they are now making up to or over 400whp NA with all out K series builds.

There's a local guy who just built up a K series. I'm not sure of the head/block combo but I do know he was running a big turbo and 2200cc injectors...he dyno'd 850hp.

If you want to go K, do a K20 head with a K24 bottom. The honda guys call it "Frankenstein" cause it's apparently the best combo for power

Something to remember, there are several versions of the K20. Those you see on craigslist are not all created equally. Most of the motors you find are going to be base model motors that were detuned to a 160hp rating. Weaker internals, lower compression, lower redline, less aggressive cams, and iVtec don't make for a simple upgrade either.

I always try to stick with that theory. If my car runs good the way it is, why should I be a meathead and put a whole different engine in just because?

For some info:
The K20A2, found in the RSX type-S...that's the hot ticket. Stock it makes 200hp/141tq at the flywheel with 11:1 compression. The K20 uses an 86mm bore and 86mm stroke. When you put the K20 head on the K24 it's like having a stroked K20 due to the longer stroke of the K24 bottom. The K24 is 2,354 cc's and uses a 87m bore with a 99mm stroke. Stock they have about 9.7:1 compression and make abbout 160hp/160ftlbs at the flywheel. Obviusly the Rev range is different between the K20 and the K24.

Why bother when you could do an F20C swap?
The K20 is pretty impressive but is mostly hype, there is nothing it could do that the F20C couldnt do better.

Also, youre very mistaken about the tuning solutions for the K series.
The OBD-I honda engines can be tuned for next to nothing, the newer engines like the K20/K24, F20C/F22C, D17, J30/J32, etc all have to be tuned with Hondata K-pro, which will set you back nearly a grand.

Because he's never going to actually do it and is just trolling.

Another thirdgen thread? :facepalm:

Yup.

Thanks for the info and opinions guys. I want to run an NA 4 cylinder so bad, while keeping the costs similar to what it does to put a turbo setup on a miata. I guess my dreams lie on a different plane than reality. I'll probably just end up re-doing my engine and putting a bigger turbo on it, just like everybody else would.

Get a reverse gear transmission so you can run a B20 or H22

Or flip the differential over and hope the transmissions oiling system will survive running backwards

TSX or Accord (accord is cheaper) block w/ civic si head + i/h/e and stage 3 skunkworks cams = 270whp, over 200ft/lbs of torque and honda reliabilty. There's info out there on what's needed to swap a k20 into an s2000, I assume the swap would be similar into the miata.

Basically it would be a tremendous amount of work and in the end it might not be worth it. It would be awesome to have 270whp, 200wtq NA in a miata and have good reliability and gas mileage.

I am not a fanboy, however I do have experience racing S2000s and Civics. In my opinion K20>F20. The K20 takes better to tuning and has equal or better reliability.

The F20 and K20 are very, very similar as they were designed around the same time (oil pumps swap, etc). You'd be vastly better off going with the F20C over hassling with the K20X#.

But I'm with the rest. I think this is just a pipe dream.

That will never happen.

K20A2's are actually 11.7:1. The K20Z1 found in the 05-06 Type S is 11:1.

Kraftwerks makes a K20 Rotrex kit. Those guys are pumping out 450whp on a C38-61 at like 12PSI.

you should sell your car and turbo this car.

http://www.uneedapart.com/images/geo-metro-parts.jpg

Well i have looked into k20 swap too. My friend drives a 2000 honda civic si with a k20z1, the car is right at 2500lbs and it made 221whp all stock on kpro tune when it was n/a. Even at 2500lbs he was able to beat bolt on srt-4s and mustangs, it was absolutley not disapointing at all, also it made 155ftlbs so thats still pretty damn good compared to what a miata makes. After about 6 months of N/A he bolted a precision 67mm non billet turbo on it and it made 430whp at 14psi on pump, all stock longblock. The civic si that came stock with the k20 came with a k20a3 or k20z3 which have considerably less power then the 20a2 and k20z1. If you plan on going turbo and rwd theres really only one way to go in my opinion, k24a4 its the accord motor, super cheap and they have made over 500whp on stock longblocks, add a2 cams and its an easy 25+whp gain, i do believe 600whp has been done on stock k24 shortblock. Check out k20a.org they have tons of info and theres even someone on there selling bellhousings for a toyota rwd 5 speed.
My only problem with the k-series swap is that it would prolly cost the same or more then a f20c and in my opinion it would be half the work to do a f20 then a k20 for approximately the same power, k24a2s are a little better then the f20c because they make tons of tq, theres a eg with a k24a2 stock motor on e85 putting down 568whp and 480 lb/ft. Stock f-series have made over 800whp and they do around 700 reliably with only headstuds.

I think a k24/k20 hybrid would make a sick stripped out track rat. For the street...why bother.

I've already decided my next swap is a K hybrid of some kind. Same difficulty as the FE3 swap only lighter, more power, better fuel economy, and more after market support.

I'm guessing 2 years, depending how long this motor lasts :P

THIS^^^ If you want to do this swap for a street car give your head a shake, only reason I'm going to is to be competitive in the class I want to run I have to be under 2000cc and make close to 300whp N/A

Xeleventy. I'm assuming the OP has never bothered to look at pricing for any of the Honda stuff.

For you guys considering this for a track car, a well-tuned K20A2 Honda weighing ~2200lbs (roughly 220whp, 160lb/ft) will definitely give a ~250whp turbo Miata a run for its money, if not walking away from it a bit. For somewhat comparative info, look up Honda Challenge H1 times. Those cars will weigh a little more in the 2500lb range, but will give you some idea of the potential. Not sure about tracks out west, but figure 2:10-11s on VIR Full. I've heard 2:09s, but haven't seen it personally. That kind of power comes out of a mostly stock motor, just header, intake and tuning.

Also, the K24 will naturally give you more torque, but at the expense of keeping revs down. They do NOT tolerate spinning too high.

My K20 civic friend and I left work last night and we decided to G-tech his car. I know a lot of people are skeptical about the G tech performance meter, and I don't swear by them, but I can tell you that on every car I ever used it on it was within 2 10ths of a second of a real drag slip time. My friends LS1 camaro G-tech'd at 12.9 on the way to the drag strip, he ran a 12.8 once we got there. My car G-tech'd at 14.4 about 2 years ago, and it ran a 14.3 that day at the strip.
Anyway, we took the 4 door Civic Si for a beat and made 4 runs. 1 of the runs the driver couldn't get it into 3rd which he claims happens all the time and it's a trans flaw with his car. 1 pass he spun big time on the launch and didn't get it into 2nd real fast...it read 16.4. The other 2 passes were consistent 15.8 and a 15.9. Eww. He was really pissed off since he just put I/H/E and Flash pro on the car, and he wasn't wanting to believe the G tech. We get back to my car, and I said, "let's line up, you yell 1,2,3 GO and we launch and see what happens, cause I know my car runs low 14's the way it sits." We did this, and I had the shittiest launch ever, but once I hit 2nd, it was like he wasn't even accelerating anymore. Due to my launch and my pussy footing, I bet I ran something like a 14.8 if that. 7psi in my car I'm guessing would be around 190whp and maybe 175 torque?? Maybe??
Based on cost, pain in the ass work, and major lack of torque...looks like I'm not doing a K swap.

Theres no doubt that you can make a new Si decently quick with some mods, and a civic swapped with a K can be really quick if you can keep it from breaking, but the exact same thing could be said for a Miata.

Comparing engines by street racing is very subjective and borderline meaningless.
For instance, I recall Tw34kd absolutely raped a Mugen Civic Si with the super badass K20A which makes 240hp bone stock. He did so in his old Civic HX with a stock D15B and an ebay turbo kit, probably not making much over 200hp.

^Thats corrct because a new mugen civic si weights over 2800lbs where as the civic hx is the lightest honda you can buy aside from a crx hf it weights about 2100. 700lbs is a big difference, even if the eg made 180hp it would prolly win, and that 240hp is only about 210 to the wheels. And typical ebay turbo kit stock civic ex which is d16w/e raped me on 8psi and i was driving a bolt on 2002 mustang bullet that made 270whp. Weight is key. And those k motors are hard to break. But i still wouldn't put one in the miata, BP is an awesome motor and with the right hardwhere it can do amazing.

Honda's are gay. Look how people post when they talk about them. It's so dumb.

Unless you're doing it for class restrictions or whatever, what's the point of swapping in another 4 cylinder?

Although I know stock k20's can make 650 whp+ on stock internals with c16 fuel.....Still would be easier to just get a LSx than have to do all the fab work of getting the k20 installed an running.