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Discussion Starter · #1 ·
Hey guys,

I have been reading up on turbo builds, and think i have a decent understanding about it. I am currently building a K24A3, and am at the stage where the entire engine is disassembled and ready to get glass blasted, painted, and get honed. Before i send it off to get honed, i am left with an important question that i cant seem to find a straight awnser for.
From what i understand, the K24A series can be boosted at low boost with stock internals. However, i also understand that turbo setups like lower compression pistons due to the amount of air forced into the compression chamber. In another post i made, i was recommended to get the engine working NA first, and then go turbo. The standard compression ratio for the K24A3 is 12.5:1, which i understand is on the high side for a turbo. However, i feel like i`ll get problems if i get lower compression pistons now with the NA setup.
So the question is, is it going to be a problem if i grab and install lower compression pistons now, or do i need to install them only when i install the turbo?

Also, apologies if this is a stupid question, i just cant find a clear awnser, sorry.
 

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2002 DC5 Type S
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Where did you read the standard compression for a K24a3 is 12.5:1? The highest compression oem K24 piston is 11.1 ratio.

You will have to choose whether you want to go NA or FI. Yes a low compression piston is best for FI, so you could start with a 10.1 piston and will be fine with that with FI.
 

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Discussion Starter · #3 ·
Where did i get that 12.5:1 ratio? Quick search online i come up with 10.5:1 even. Guess my mind messed up. I feel stupid now, since 10.5:1 should be low enough compression for FI like you said. If you want, you can close this stupid question of mine haha. 🙍‍♂️
 

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96 civic HX K24a
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Where did i get that 12.5:1 ratio? Quick search online i come up with 10.5:1 even. Guess my mind messed up. I feel stupid now, since 10.5:1 should be low enough compression for FI like you said. If you want, you can close this stupid question of mine haha. 🙍‍♂️
You are good to send it to the moon on a stock engine. A skilled tuner and e85 should keep it safe enough @500 or so whp but you’re probably going to blow the trans sooner than later If you don’t have a twin disk.
 

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Discussion Starter · #5 ·
E85 is hard to come by here. I`d want to stick to pump gas. We have E10 and E5 as fuel choices so i probably wont run too much boost anyway. At what whp would you say a twin disk clutch is needed? Cause my engine didnt come with one, nor did my transmission. So i have free options there.
 

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E85 is hard to come by here. I`d want to stick to pump gas. We have E10 and E5 as fuel choices so i probably wont run too much boost anyway. At what whp would you say a twin disk clutch is needed? Cause my engine didnt come with one, nor did my transmission. So i have free options there.
Technically you don’t “need” a twin disk till you’re comjng up on 800-1000whp but on a 5-600 hp car that gets used alot it will take most of the abuse and the gears will last longer. You are still good to use a super single or comp stage 5 / fx500 clutch masters etc but in my opinion over clutching the car doesn’t hurt.
 

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Where did i get that 12.5:1 ratio? Quick search online i come up with 10.5:1 even. Guess my mind messed up. I feel stupid now, since 10.5:1 should be low enough compression for FI like you said. If you want, you can close this stupid question of mine haha. 🙍‍♂️
my intention was not to make you feel stupid and I am sorry if I came across as such. Questions regarding your engine or build plans are not stupid questions. I wish I asked more questions over the past two decades in my involvement of builds and projections.

You will notice on this forum, we do not bash people, and the sole purpose of our community is to help others. Without advertising this fact, the majority of the members (98%) here are about returning the information and help we have received along the way.
 

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Discussion Starter · #8 ·
my intention was not to make you feel stupid and I am sorry if I came across as such. Questions regarding your engine or build plans are not stupid questions. I wish I asked more questions over the past two decades in my involvement of builds and projections.

You will notice on this forum, we do not bash people, and the sole purpose of our community is to help others. Without advertising this fact, the majority of the members (98%) here are about returning the information and help we have received along the way.
No no, it wasnt you who made me feel stupid. It was me making myself feel stupid. I dont know how i thought the CR was 12.5 when i clearly read 10.5. Perhaps its because i saw some 12.5 pistons that somehow stuck inside my head.
 

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Your honesty is awesome brother. So I want to share this with you, if you are planning to boost your engine research restoring the cylinder head. I wish I had taken a good look at restoring my cylinder head correctly, or the best I can possibly afford. What do I mean by restoring the used head - restoring compression from the head side, restoring correct valve spring pressure, restoring the valve & valve seat sealing surfaces, having the spring pressure tested, testing to see if a shim is needed under the valve spring to maintain spring pressure for proper valve seating, having the head milled etc.

Not only is this great for any used engine looking to prevent the declining, without doing this on a higher mileage engine (100,000 miles), the engine will decline even at a faster rate. If you are going to boost, one of the main goals is to keep boost pressure in and not blowing past the exhaust valves or leaking by the intake. Having valves that do not seat well, having worn valve guides, worn valve springs, worn valves and/or valves that have even the slightest bend to them will not seat properly, pitted exhaust valves, old cylinder head sealing surface, etc. are all part of having a head that love to be addressed. The added heat from the boost will also play a factor in the life of the valves, valve seats, etc. Leaking valve guides is not great when mixing into the air/fuel ratio and quality of combustion.
 

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Discussion Starter · #10 ·
I actually did a little research on restoring the cylinder head. I bought the engine from a guy that included a bunch of parts including new valve guides, race bearings, seals, etc. I already did the cilinder head but when i go turbo, i`ll take a look into the valve springs. They look fine for now, but if i put more load on them due to the turbo, ill probably look into replacing them. Atm,since my block is completely disassembled, i will check the pistons, replace the piston rings, get the block honed, and then reassembled.
 
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