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View Full Version : k24a1 head vs k20a2 head swap



kale's blue ep3
01-15-2011, 08:59 PM
Whats the big difference?

For now with my budget i want to stick with the k20a3 bottom end. Could i get the same power out of each head.

R34L-St4tus
01-15-2011, 10:01 PM
k24a1 can just bolt right up to the k20a3 bottom, plus its the best combo for a a3. i forgot what needs to be done for the a2.

EP3Casas
01-15-2011, 10:06 PM
a2 needs 310cc injectors and i would recommend an a2 oil pump other than that everything bolts right up just like the a1 head. You will also need K-pro for both

But i would just go a1 it has more flow at stock specs than the a2 and better driveability.

kprocivic
01-15-2011, 10:09 PM
a2 needs 310cc injectors and i would recommend an a2 oil pump other than that everything bolts right up just like the a1 head. You will also need K-pro for both

But i would just go a1 it has more flow at stock specs than the a2 and better driveability.

troof.

kale's blue ep3
01-16-2011, 12:34 AM
So the a1 would be better in the long run?

EP3Casas
01-16-2011, 12:37 AM
yes. or just save up and k24 swap

talonXracer
01-16-2011, 07:09 AM
a2 needs 310cc injectors and i would recommend an a2 oil pump other than that everything bolts right up just like the a1 head. You will also need K-pro for both

But i would just go a1 it has more flow at stock specs than the a2 and better driveability.

The A2 head DOES NOT require 310 injectors on the A3 bottom end, you will be substantially below A2 power levels.

ABSOLUTELY NO NEED to swap out the oil pump for an A2 pump.

The A1 head does NOT flow more air than the A2 head, the A1 head flows better at lower lift and durations(small cams) as soon as you go above stock lift and durations the A1 flows less than the A2 head, but it does flow alot better than the A3 head.

Cleaning the ports and port matching will get the A1 head flowing identical to the A2 at the same lift and durations.

kale's blue ep3
01-16-2011, 11:54 AM
But with the a2 head will have true vtec? And the a1 will not? What's so bad about the a2 head on then a3 bottom end

talonXracer
01-16-2011, 12:11 PM
You will not make nearly as much power as a true A2 and if you try to use the A2's ECU, a bolt-on equipped A3 will walk you.

A great mod if boosted with Kpro!

Any mod like this will require Kpro to get it running correctly.

Another great setup that is cost effective, is a complete K24A4 swap, with 310 injectors along with a completely stock EP3 intake and exhaust and it will run fine on the stock EP3's ECU.

I have heard of a complete K24A1 swap with it's stock plastic dual runner intake mani, 310 injectors being run with a base RSX ECU, this should be able to be used in the EP3 as well.

kale's blue ep3
01-16-2011, 01:41 PM
What about a2 head kpro and full bolt ons?
Would that be pretty good? Better than just a a a3 with kpro and full bolt ons?

EP3Casas
01-16-2011, 02:16 PM
the a1 will still flow more. unless you add cams. by that time it would be more cost effective to go swapped OR Vtec killer a1/a3

kale's blue ep3
01-16-2011, 06:58 PM
so a1 over a2 with the a3 bottom end?

R34L-St4tus
01-16-2011, 08:20 PM
so a1 over a2 with the a3 bottom end?

its up to you, both have pros and cons. if i was you i would just do a vtec killer cam setup on the a3 and call life good. until the motor gives then just do a swap. if you don't have kpro, i would just stick to a bolt on a3 till you do get kpro.

talonXracer
01-16-2011, 08:34 PM
What about a2 head kpro and full bolt ons?
Would that be pretty good? Better than just a a a3 with kpro and full bolt ons?


the a1 will still flow more. unless you add cams. by that time it would be more cost effective to go swapped OR Vtec killer a1/a3

The A3 bottom end with a A2 head, kpro and boltons will be a decent setup, easily walking any A1 head swap w/cams, Kpro and boltons.

But as mentioned above the cheaper route(and sounds real cool idling) is the A3 with Vtec killer setup

EP3Casas
01-16-2011, 11:09 PM
The A2 head DOES NOT require 310 injectors on the A3 bottom end, you will be substantially below A2 power levels.

ABSOLUTELY NO NEED to swap out the oil pump for an A2 pump.

The A1 head does NOT flow more air than the A2 head, the A1 head flows better at lower lift and durations(small cams) as soon as you go above stock lift and durations the A1 flows less than the A2 head, but it does flow alot better than the A3 head.

Cleaning the ports and port matching will get the A1 head flowing identical to the A2 at the same lift and durations.

just saying thats what i would do.

and my post said for a1/a2 flow comparison at STOCK specs it flows better. you have corrected me in the past about the flow. thats why i said that :wink:

kale's blue ep3
01-17-2011, 12:09 AM
staying a3 with the vtec killer setup and kpro be reliable?

talonXracer
01-17-2011, 07:41 AM
just saying thats what i would do.

and my post said for a1/a2 flow comparison at STOCK specs it flows better. you have corrected me in the past about the flow. thats why i said that :wink:


But i would just go a1 it has more flow at stock specs than the a2 and better driveability.

But your insistence on the fact the A1 is a better swap is oh so wrong on many points, it is a decent swap if you want to retain the economy mode of VTEC, but it produces far less whp than the A2 head swap and with Kpro there is absolutely ZERO drivability issues.

On the flow bench the A1 DOES NOT outflow the A2 when comparing flow at specific points using their respective stock cam profile specs, even using stage3 2lobe cams show less flow than with stock A2 cam profiles. Using A2 cam specs, the A1 flows better down low, but falls off at higher lifts and durations.

EP3Casas
01-17-2011, 08:14 AM
But your insistence on the fact the A1 is a better swap is oh so wrong on many points, it is a decent swap if you want to retain the economy mode of VTEC, but it produces far less whp than the A2 head swap and with Kpro there is absolutely ZERO drivability issues.

On the flow bench the A1 DOES NOT outflow the A2 when comparing flow at specific points using their respective stock cam profile specs, even using stage3 2lobe cams show less flow than with stock A2 cam profiles. Using A2 cam specs, the A1 flows better down low, but falls off at higher lifts and durations.

i understand now.

OP listen to doug. he knows.

talonXracer
01-17-2011, 08:19 AM
Now with just port matching the A1 head, the heads could be virtually identical in flow. The ports on the A1 are slightly smaller which help the low end but detract from the top end. The A1 uses the same intake as the base RSX it has smaller port dia's than the A2's(and ep3's) mani.

kale's blue ep3
01-17-2011, 10:18 AM
so when getting kpro it would be for whatever year head i get?

talonXracer
01-17-2011, 10:49 AM
Nope, kpro could care less what head you have, you would just load the appropriate calibration for your setup and then street tune.

kale's blue ep3
01-17-2011, 11:42 AM
Thanks talon im just trying to get some kind of plans for this summer.

so kpro is basically unversal with all k series?

talonXracer
01-17-2011, 11:56 AM
That is correct for the EP3. Some Kseries engines will require the removal of the drive by wire TB and the EP3's TB installed.

But not all Kseries ECU's can have Kpro installed and Kpro does not neccesarily work in every chassis with a kseries engine.

sincityep3
07-12-2012, 01:11 PM
for the a1/a3 vtec killer set up do you just get the complete a1 head and throw a2 cams in to make it vtec killer?

Gilmour
07-20-2012, 07:47 AM
for the a1/a3 vtec killer set up do you just get the complete a1 head and throw a2 cams in to make it vtec killer?

I’d suggest a bit of seat time in a vtec killer a1/a3 setup before you invest in this swap. It’s not for everyone, especially if the car is a DD.

Blah1219
07-20-2012, 01:22 PM
for the a1/a3 vtec killer set up do you just get the complete a1 head and throw a2 cams in to make it vtec killer?

The k20a3 and k24a1 valvetrain are the same. I would suggest getting k20a2 valvetrain while you have the head if you plan to take it to 8k redline.