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K24a2 short motor worth it over a K24a1?

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8.1K views 18 replies 11 participants last post by  doug2507  
#1 · (Edited)
Hi Guys

Just wondering if its worth paying the extra cash for an a2 short block over the more common a1 / a4

I intend to build the short motor with aftermarket rods and pistons and mate with a k20a2 head.

As far as I can tell from searching the boards, the a2 has more counter weighting on the crank and oil jets for the pistons.

Are these features worth the extra 500 -700 bucks premium?
 
#2 ·
i thought the counter weight thing applied to k20a2 vs k20a3? afaik only difference in k24 cranks is a coating that tsx has and some ppl say it was balaanced better from factory. fact is though tons of ppl have used k24a1/4/8's on motor builds and made great power and lasted. if going with aftermarket rods and pistons it really does not matter. if you are worried just have your rotating assembly balanced when you have your machine shop fit your pistons/rods etc.
 
#3 ·
they have oil squirters that jet oil at your cylinders, which is more ideal if you're wanting to road race. But for drag racing or street driving with an occasional street race, it's not necessary. Those oil jets can also be drilled and tapped into whatever block you have. But it'd be worth it for me because I would like mine to be able to take sustained high revving for long periods of time.
 
#4 ·
I dont see the sense in paying so much for a short block if you're going to rebuild it. Just find the cheaper A1/A4 block, unless the A2 block is going for the same price, then it's all up to you.
 
#5 ·
I've tracked down a k24a3 block locally

When it comes to getting the head ported I don't suppose it matters if you use the k20a2 or k24a3 head, as the Cnc program will supply the same result with either right?
 
#8 ·
It's a personal choice, plus it comes down to the deals you find. Sure the A1 and A4 blocks are cheap, but if look around and are patient, a tsx shortblock can be had cheap too. I picked up a full K24A2 for $400 last year, seems pretty cheap to me!!

People are also going to tell you that the other cheaper blocks have cranks that work fine with no problems, and the do...BUT, miss some of the advantages! If I were to use a B series crank out of a non vtec B18B as an example, and compare it the one found in a type R B18C5, both cranks are great! But, the difference is the type R crank is "fully" counter balanced, and weights a bit more. the advantage of this is the at high rpm when in vtec, the Type R crank that weighs more is 30% more smooth with less vibration!! Both work, but one works better!

This is also the case with the tsx crank found in the K24A2. Aslo, the rods are thicker and stronger from factory. I don't know, the choice is yours......
 
#9 ·
Thanks for posting this I am in the exact same dilemma and have been searching a good forum covering this- day n night for the last couple weeks because I can get deal on a1s local frm 3 guys but the only one who wants to sell a2 won't sell me the block. I don't need the whole motor because if I did I would go to h motors and still pay less and have a warranty than what dudes charging. I think I'm gna order supertech 12.5:1 87.5mm pistons within the next 2 days because I'm just gna get block off my guy.
 
#11 ·
Thanks for posting this I am in the exact same dilemma and have been searching a good forum covering this- day n night for the last couple weeks because I can get deal on a1s local frm 3 guys but the only one who wants to sell a2 won't sell me the block. I don't need the whole motor because if I did I would go to h motors and still pay less and have a warranty than what dudes charging. I think I'm gna order supertech 12.5:1 87.5mm pistons within the next 2 days because I'm just gna get block off my guy.
I feel u on that too , Deetz. Small differences account for the patience we need . I'm gna try and find an k24a2 because I won't build bottom end and it'll be less hassle. It's a win win either way tho both will make good numbers
You're in two minds, find out 100% what you wanna do before you buy parts, that gets expensive, trust me.
 
#10 ·
I feel u on that too , Deetz. Small differences account for the patience we need . I'm gna try and find an k24a2 because I won't build bottom end and it'll be less hassle. It's a win win either way tho both will make good numbers
 
#12 ·
Yea money isn't big problem but I'm not gna buy a whole motor if I only need block and spend xtra on that. I just found an a2 on this dc5 facebook page somebody is selling but he said a cylinder needs honed so I'm weighing my options. Feel like I can find a nice reggie k24 bottom end n just throw some supertechs in it and some decent rods for 1400 when I'd have to pay that for a tsx motor alone
 
#13 ·
Just find the cheapest block to use since you're over boring and building anyway. Don't matter if it's A2, A4 or A1.

I used wiseco 87.5mm pistons and Manley H beam rods with all OEM bearings and OEM K20A2 oil pump in my A1 block. Pretty simple build.
 
#14 ·
Nice.what type of power did you make? What are you revving to ? Also which bearings did you use oem or acl? That's pretty much the same set up i was going to go with and haven't been able to talk to anyone with similar set up @brakaT
 
#15 ·
The motor is just sitting. I haven't got the interest at the moment for anything car related.

User F-BOM has a similar setup, pm him. He's making around 270whp IIRC revving to 8100rpm.
 
#17 ·
Another plus for the k24A1 block is the RSX oil pump is a direct swap in, no need to make the little notch like you do on the k24a4. I don't remember if it were necessary on the k24a2 though, its been a while since I did all of that searching around when I was building my motor.