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Old 07-11-2011, 09:54 AM   #1
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Default 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?
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Old 07-11-2011, 09:58 AM   #2
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Why would you even consider this? What a waste of time.
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Old 07-11-2011, 09:59 AM   #3
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K swap it
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Old 07-11-2011, 10:09 AM   #4
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K20 then turbo?
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Old 07-11-2011, 10:19 AM   #5
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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 ****-ton of work and not much gain. If you didn't already have the turbo stuff this would be a different story.
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Old 07-11-2011, 10:35 AM   #6
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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.
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Old 07-11-2011, 10:47 AM   #7
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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
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Old 07-11-2011, 11:02 AM   #8
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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.
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Old 07-11-2011, 11:20 AM   #9
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Quote:
Originally Posted by hustler View Post
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 ****-ton of work and not much gain. If you didn't already have the turbo stuff this would be a different story.
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.
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Old 07-11-2011, 02:23 PM   #10
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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.
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Old 07-11-2011, 02:27 PM   #11
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Quote:
Originally Posted by Full_Tilt_Boogie View Post
Why bother when you could do an F20C swap?
Because he's never going to actually do it and is just trolling.
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Old 07-11-2011, 02:31 PM   #12
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Quote:
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Because he's never going to actually do it and is just trolling.
Another thirdgen thread?
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Old 07-11-2011, 02:56 PM   #13
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Quote:
Originally Posted by Full_Tilt_Boogie View Post
Another thirdgen thread?
Yup.
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Old 07-11-2011, 03:07 PM   #14
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Originally Posted by Full_Tilt_Boogie View Post
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.
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.
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Old 07-11-2011, 03:36 PM   #15
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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
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Old 07-11-2011, 04:26 PM   #16
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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.
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Old 07-11-2011, 09:32 PM   #17
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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.
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Old 07-11-2011, 09:48 PM   #18
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Quote:
Originally Posted by thirdgen View Post
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. .
That will never happen.
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Old 07-11-2011, 10:14 PM   #19
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Quote:
Originally Posted by thirdgen View Post
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.
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.
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Old 07-11-2011, 10:43 PM   #20
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you should sell your car and turbo this car.

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