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A3 to A2 block conversion OR K24A1

5K views 14 replies 4 participants last post by  tallblondkid 
#1 · (Edited)
I am beginning to process of converting my EP3 A3 block to an A2. I will be keeping the A3 head.

My EP-A3 has been turbo'd for nearly 10 years with around 300whp. As of late, I have been burning oil and compression has fallen off. 145 across all 4 (give or take).

I have decided, since I have to open it up, I might as well upgrade it (on a budget-ish...)

Here's the plan:

A2 Pistons (+ceramic coating)
A2 Rods
A2 Crank
A2 Oil Cooler w/ Water pump/passage assembly
-prelude or s2000 cooler joint
A2 Oil Pump w/ pan, baffle, chain, etc.



Superior Automotive in Anaheim is going to do the machining work:
-balance and polish the crank
-match piston rings and bearings to the rods and assemble the short block

Questions:

What piston rings do you recommend?
-Superior recommended Total Seal, thoughts?

Will I have any head/valve clearance issues with the A2 internals?

Will compression ratio be affected with the A2 internals? Will it still be 9.8:1, or up to the A2's 11.0:1?

Even if it's ok, should I replace the head gasket? If so, should I use an A3 or A2 head gasket?

Lastly, in terms of hp, we have all seen stock A2's make more than 450-500whp. I am not looking for that much power, but wanted to fall somewhere in the 350-380whp range. The A3 common breaking point is anything over 300whp (rods snap). What is the common breaking point number for the A2?


OORRRR

I am now considering a K24A1...
 
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#6 ·
Then your not going to gain much, you'll just be able to rev it a bit higher.

You'll yield more results from swapping in a K24a1 or 8 motor. It's going to be cheaper as well.
 
#9 ·
Well the A3 head would be a limiter since it only has two lobe cams and not three like the A2 head. However it's kind of a moot point, since your planing on still utilizing the A3 head in your build.

I made my suggestion on a k24a1 block, based on its ability to handle high hp (boosted) in stock forum, and it's pretty inexpensive to purchase. I would foresee the cost of building the A3 block with new stock A2 internals to be pretty expense, and you could sink those funds into something that would net you more power.
 
#11 ·
It is your suggestion that has now got me researching K24s.

No matter what block I get, I intend to machine it to get another 10 years out of it with new rings and bearings. I'm not going to put someone elses leaky rings in my car to have to rip it open again next year.

My options:
1) buy K20a2 longblock or shortblock- pull pistons, rods, crank, water pump/passage, oil cooler and pump and move them over to a machined A3 block (no squitters) and keep running the A3 head. I haven't read anything that states the A3 head can't handle 350-370whp.

2) buy k24a1 longblock or shortblock- use complete longblock or move A3 head onto a short block. Still have to buy K20A2 Oil pump, pan, etc + a form of oil cooler, motor mount, amongst other A2 things.

I have yet to really price the options out to see what is more cost effective. Anyone want to give me some pro's and con's?
 
#12 ·
What ever path you choose, I suggest you buy a brand new A2 oil pump. (You talk about using a used one in option 1)

The K24a1 head casting far out flows the k20a3 head (hell the k24a1 head has been know to out flow the K20a2 head on bench tests). In chart below K24a1 is yellow.


If you do choose to go option 2, you don't need new motor mounts for your EP3, its just the passenger side bracket from the CRV you need.

If building the k24a1 block you could use tsx rods, or after market if running big power.
 
#13 ·
Thanks Ridge- good info, I'll look for a longblock if I go that route. Can the A1 head be converted to 3 lobe vtec?

With an A2 oil pump- which I will buy new, what can the K24A1 rev to safely?


Also, is the K24 block casing taller/bigger? does the head sit higher in the engine bay? I need to consider my turbo-firewall clearance as well as my downpipe and IC piping.
 
#14 · (Edited)
In a sense it can be converted to use three lobe intake and exhaust cams, however it's locked on the high lobe cam (may be a bit much for a dd).

What can you rev it to safely. That's debatable, and many people have different opinions. If you where ever part of ephatch there was a member on there call Lucid Moments, he ran a stock block K24a2 with upgrade valve springs and cams, up to 8k, plus he was boosted with a JRSC.

Yes taller 19mm (I'm Canadian) so thats about 3/4 of an inch
 
#15 ·
Lol at Canadian. Some of us Americans understand the metric system. Lol

I do remember lucid moments. I miss how good that forum once was.

I'm not worried about revving super high, but I like my gearing for track revving to 7300-7500. I know the A1 is 6500, and wondering if I used tsx rods if that 7200 is undebateably safe.

Knowing that the deck is 19mm higher changes things. I need to confirm the turbo will fit and see how much the IC piping needs to change. I was already going to get a new downpipe so it rests on those two things. Won't have the turbo back for another week or two from being rebuilt and I'll have to wait until then to figure it out.
 
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