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Hi. I was wondering if you guys could tell me why the k20a2 is considered so much better then the k20a3. I've been trying to research both of these and it's hard to find good info over the internet. I can't see for myself why the a3 doesn't have the same potential as the a2. i ask mostly because i have an 05 civic si with the a3 in it and I would rather not swap it at all. I mean i'm not looking for ungodly amounts of horsepower. it just seems to me that i could still be happy with it with the typical things such as rebuild, turbo, and aftermarket anything i can get my hands on. Tell me whatever you guys can about the two and please provide substantial evidence when you can. Thanks.
 

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Re: Trying to educate myself on the k series

well, what are the goals in power, that would help us point you in the right way of thinking, also, are you an n/a guy or do you not care how you get the power?
 

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Re: Trying to educate myself on the k series

Hi. I was wondering if you guys could tell me why the k20a2 is considered so much better then the k20a3. I've been trying to research both of these and it's hard to find good info over the internet. I can't see for myself why the a3 doesn't have the same potential as the a2. i ask mostly because i have an 05 civic si with the a3 in it and I would rather not swap it at all. I mean i'm not looking for ungodly amounts of horsepower. it just seems to me that i could still be happy with it with the typical things such as rebuild, turbo, and aftermarket anything i can get my hands on. Tell me whatever you guys can about the two and please provide substantial evidence when you can. Thanks.
Welcome to the site :up:

The A3 motor is has some things holding it back.
-lower compression
-crank is not as well balanced as the K20A2 (cannot spin as high)
-no oil squirters from the factory (can be installed, but not needed on forged pistons)
-weaker rods
and the biggest draw back is the head.
Because power is a function of energy and time you need to do a couple things to make more of it, and the motor must be strong enough to do these things.
The way that we get more energy is by adding more Air and Fuel into the motor.
The head design, intake and exhaust ports, and adjoining components such as the header and intake manifold will dictate total flow.
This is the major issue with making considerable power all motor with the A3, the head design.
The A3 motor, like the K24A1 and the K24A4, does not have traditional VTEC as we have seen it on the B-series. Instead, the A3 motor has a 'economy' VTEC.
http://www.k20a.org/forum/showthread.php?t=27470
At low RPM only one valve on the intake side opens, this allows the air to swirl as it enters the cylinder. This swirl action speeds up as the piston rises, and it aids in mixing the air/fuel, allowing for a more complete burn. When VTEC engages in the K20A3 head it opens the second valve on the intake side, but it retains the same lift/duration as the first valve.
The K20A/2 heads have the traditional VTEC that was in the B16, both valves open at low RPM, at high RPM when VTEC engages both valves are opened higher and for a longer time.

That is the energy side of it, now for the time side. (energy x time = power)

Time is your RPMs.
The A3 crank and A2 crank are considerably different, below is a picture from this thread
http://www.k20a.org/forum/showthread.php?t=9635


The A3 crank is the bottom one in the pic. As you can see it has less counterweights on it. Counterweights help keep the crank from 'wobbling' in the journals after a specific RPM. A better balanced crank will allow you to achieve a higher RPM, but remember, your induction, exhaust, camshaft and piston selection should warrant the need for higher RPM.
 

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Re: Trying to educate myself on the k series

wow thanks this info has really helped. now with this stuff in mind i have a couple more questions. if i didn't care about economy couldn't i just get cams with maximum duration. and could i swap the a3 crank for an a2? thanks again.
 

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Re: Trying to educate myself on the k series

You would want to up the compression if running larger cams. The A2 crank with some decent rods and about 12.5-13:1 compression pistons will be good.
You will need K-pro or AEM EMS for tuning. K-pro is a bit more user friendly and generally cheaper. Both offer about the same features.
With using the aftermarket pistons in the A3 and larger cams be sure to clay the motor for piston to valve clearances.
One other thing to consider, especially on a daily driven all motor car, is gearing. Adding a TSX sixth gear and a 5.0 final drive is probably the best bang for the buck mod you can do on the EP3.
 

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Re: Trying to educate myself on the k series

You would want to up the compression if running larger cams. The A2 crank with some decent rods and about 12.5-13:1 compression pistons will be good.
You will need K-pro or AEM EMS for tuning. K-pro is a bit more user friendly and generally cheaper. Both offer about the same features.
With using the aftermarket pistons in the A3 and larger cams be sure to clay the motor for piston to valve clearances.
One other thing to consider, especially on a daily driven all motor car, is gearing. Adding a TSX sixth gear and a 5.0 final drive is probably the best bang for the buck mod you can do on the EP3.
would this setup be alright with a turbo, what kind of boost would i want to run if so? And as for the sixth gear thing, I would have to swap in the whole tranny right?
 

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Re: Trying to educate myself on the k series

would this setup be alright with a turbo, what kind of boost would i want to run if so? And as for the sixth gear thing, I would have to swap in the whole tranny right?
For turbo you would want to use lower compression pistons, or stock. Plenty of K20A2's have seen 400whp stock block on about 10psi.
Not sure about the K20A3, but I imagine it would take more boost, and the motor would be under a lot more stress at the same psi.
There is a great turbo kit for sale very cheap in the For Sale section here. Slap that on a K20A2 and you have a great 400hp package for about $4500 :up:
 

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Re: Trying to educate myself on the k series

would this setup be alright with a turbo, what kind of boost would i want to run if so? And as for the sixth gear thing, I would have to swap in the whole tranny right?
No. Generally you will want lower compression for a turbo setup. usually anywhere from 8-10.5. The amount of boost you will be able to run will depend on modifications done to the engine and the size of the turbo you have.
Swapping out the tranny is not mandatory. You can add the 6th gear to the transmission you have but if you are not good with tearing down and rebuilding transmission or dont have a shop to do it for you, then you may not want to pull it apart and just buy a 6spd transmission.
 

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Re: Trying to educate myself on the k series

Good Aaron. You beat me to it... :up:
 

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Re: Trying to educate myself on the k series

you well find all the info you need on here

this website is the shit i learned a lot


and for your a3 get kpro and turbo that bitch if you want some power
 

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Re: Trying to educate myself on the k series

No. Generally you will want lower compression for a turbo setup. usually anywhere from 8-10.5. The amount of boost you will be able to run will depend on modifications done to the engine and the size of the turbo you have.
Swapping out the tranny is not mandatory. You can add the 6th gear to the transmission you have but if you are not good with tearing down and rebuilding transmission or dont have a shop to do it for you, then you may not want to pull it apart and just buy a 6spd transmission.
not tring to thread jack but the adding 6th gear caught my eye

what do i need to do this the 6 speed tranny
gears and forks?

and how expensive is it?

if theres a thread already please hook me up with the link very interested
 

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Re: Trying to educate myself on the k series

not tring to thread jack but the adding 6th gear caught my eye

what do i need to do this the 6 speed tranny
gears and forks?

and how expensive is it?

if theres a thread already please hook me up with the link very interested

See above post.
 

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Re: Trying to educate myself on the k series

I most say this site seems more noob friendly than some of the other sites I am part of. Very good read here and signalpuke your on top of things here thanks already...
 

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Re: Trying to educate myself on the k series

I most say this site seems more noob friendly than some of the other sites I am part of. Very good read here and signalpuke your on top of things here thanks already...
Thank you for the compliment.
We (the staff and supporters of the site) try to make it easy for people who are new to the K-series to come to the site and learn the basics. While we may not be 'johnny on the spot' with an answer all the time, we usually come through with due diligence.
I always recommend that people check out the DIY/FAQ thread first. I know that clicking on that link makes people think they are committing themselves to noob'dom, but even I forget stuff sometimes and it is a good refresher.
As always, the best way to learn is with your hands, and not by typing on a keyboard. :wink:
 

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in my school we have a conservative build on a ep3 hatch, (your motor) and its a greddy turbo kit, the car makes 200 whp, but it makes 180 at 3000 rpm, so this car is a torque beast, you can defiantly have a lot of fun with this car on the street. I think the car is only at 8 psi too .
 

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in my school we have a conservative build on a ep3 hatch, (your motor) and its a greddy turbo kit, the car makes 200 whp, but it makes 180 at 3000 rpm, so this car is a torque beast, you can defiantly have a lot of fun with this car on the street. I think the car is only at 8 psi too .
what school???
 
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