Question On Ka24de bottom end engine rebuild

[super_240]

Okay so heres the deal.. I bought a 91 240sx ka24de for $500 the top end of the engine has been totaly rebulit with performance parts and the guy i bought it from didnt rebuild the bottom end and he blew the bottom end of the engine and i was wondering whats parts i would need to rebuild the bottom end and where is a good place to get the peformance parts at i am also going to be adding turbo in the near future so im wanting it to be able to withstand turbo and still be able to drive without the turbo till i get it.If anyone can help me out on anything that would be great im new to modding my engine but am willing to learn so any help i would apperciate ThanksJimmy__________________

[Chezedik]

Depends on how turbo you want to go. I am going to pull between 300-350, and the bottom end can take that and more. You obviously will need a head set and conversion set. You will need rod and main bearings. Crank seal and Rear Main. New rods and pistons if you plan on going nuts. What turbo do you plan to use? At what pressure (max)?

[super_240]

Right now im not going for a big turbo maybe 250 but im still studying up on it i really dont much about turbos im more of and audio tech then a turbo tech but im gonna study up on it but i will only be going for maybe 225 or 250 max not much should stock be able to handle it if i went to nissan and got oem parts?

[tysonegrub]

The stock bottom end is really overbuilt ive seen shops hit 600 rwhp on stock cranckshafts but the pistons can only handle 240 at the wheels and thats only pushing 7 psi of boost anything after that you will need aftermarket pistons now with the connecting rods they will handle roughly 300 but if you get pistons your going to need the rods in my opionion and your question to running aftermarket low compression without a turbo is fine because stock compression is 9.5 to 1 and you need 8.5 to 1 so it is not going to harm the engine in any words you will have less power in the lower rpm's though.

[Chezedik]

Tyrone could not be more wrong. The stock bottom end sees 10-15psi in the KA-t forums alll the time. The pistons have been known to break 400hp, but shortly after they may not be enough for the higher boost levels. The rods will also get weak. You can use a T3 to pull the sort of power you want, and the stock bottom end is more than sufficient. Especially, with proper tuning.

[super_240]

alright so i will just that the bottom end rebuilt with stock parts or something as soon as i finish paying the rest of the car off its going to get rebuilt Thanks Chezedik

[Chezedik]

sounds like a better plan. Speak to Jookmasta, he is doing exactly what you want to do with a T3 and he will be happy to help you.

[tonynalli]

just different pistions will do the job..but if oyu plan on pushing any more then 400 to the wheels safely then you need to spring and get some rods...so its really up to you..ive seen some blocks handly 350 all day long and some that die at 250..its just depends on how well the motor was taken care of...

[s14 2510's]

New aftermarkit pistons should be all you need to upgrade to hold that power. I would just rebuild everything else back to new oem specs and replace all the seals. and get the block decked for a good seal of the head

[Chezedik]

Are you guys talking to me?

[aggies13]

We just rebuilt the lower end for a SOHC -> DOHC swap. It was a car with a blown head gasket, so internals were decent. We just cleaned the piston grooves, replaced rings and bearings, honed the cylinders, and we're just about finished with the head. We're shooting for 300whp and were told that stock internals are fine for that number.

[TrueSlide]

300WHP has BEEN done, but would you really want all your hard earned parts and time to goto waste cause you did not prep correctly. What is so hard about putting in forged pistons as GREAT insurance on your project.

[Chezedik]

Nothing, but they are absolutly unnecessary. It is all about good tuning. There are guys on the boards pulling 350-400 on stock internals. 400 has been hit on stock parts, but at that point, even the most diligent tuning may not be enough. Everyone is worried about what the KA can handle, but on the KA-t forum, they're living it. Just ask them.

[TrueSlide]

Oh I know what he KA is capable of. I know more then what you probley think.

But honestly would you want to trust cast pistons running 300whp that you just beat on?

[Chezedik]

Uhm, maybe a good point. But they are a dime a dozen, so if I pop it, I'll just get a spare for a 300 or so.

[TrueSlide]

Uhm, maybe a good point. But they are a dime a dozen, so if I pop it, I'll just get a spare for a 300 or so.

lol, so true though.

I did get a running KA for free though.

[deviousKA]

You should always get the cylinders properly bored, new sized pistons (oem equiv. or other), cleaned/polished crankshaft and new bearings at a minimum when rebuilding you short block.

In order to get anything near a proper crosshatch on the cylinders for proper ring break in you will be taking to much material causing to wide of tolerance for a cast piston. With a forged piston, you have more tolerance to work with generally but you will still be reaching the wide end of the specified range. Combine this to the fact that the effort involved in properly honing (to provide wide tolerance and untrue cylinder) cost more than the $50 to get the block properly bored.

You will have a longer lasting, more dependable, and more powerful engine if you are serious about doing it right.

If you do want to just re-ring and hone the cylinders, be sure you are aware of the proper cut and crosshatch that is necessary, and that you are not using chrome moly rings.