airman

Hey all, first post. I'm starting to do a little bit of research on what i'm going to need when building my future 240sx (ka24det to be). I want a '91-'94 S13, but I plan on fully rebuilding it. Because i'm going to be building it anyways, I'm looking for one that needs help (like a blown head gasket, or something along those lines that can be found for cheap). However, that's against the point.

The block will be bored 20 or 30 over, new rods, pistons, crank turned/resurfaced, yada yada. As far as head work though, I plan on going with a more agressive set like 264 or 272 cams. I wont be turboing this setup immediately, i plan on doing things one step at a time, as i'm not going to rush the project. I'll have more questions on that later.

ANYWAYS, my question is this. I will be having the head machined/cleaned up/etc, but since I'm throwing some nice big cams in the car, is it necessary to spend $300-$400 (amount of labor on all of the machine work on the block and the head ) on a set of BC springs and retainers, or some other name-brand? It will, of course, be getting new seals and have the valves cleaned up, unless I am recommended to spend the money on a set of aftermarket valves as well, or if they need replacing anyways. If they just need replacing, would an OEM set of valves for less than a third of the cost of BCs be okay?


For example, I had my head from an old eclipse of mine machined and fixed up and it went from this:



to this:



Those are the original, stock valves, all cleaned up. The machine shop I deal with does VERY good work.


Looking further in: with a built bottom end, like I am planning on, I am looking for ~400hp which I think that is reasonable if I take my time and do it right. With horsepower levels that high, as far as head work goes, i know i will at LEAST be doing cams/new seals/cleaning valves/resurfacing the head. What do you guys think about spending over $600 for a set of valves (assuming the ones in it aren't worn or need replacing), springs, and retainers? Necessary?

I have set my goal for 400whp, which i'm pretty sure is reasonable. But with a built bottom end, forged pistons, built (although not sure how "much") head, and something like a GT28R or a GT30R, and i'm pretty sure the gt30r can do ~25+psi, assuming correct fuel delivery, suspension, all electronics goodies, etc, would this setup hold that and not fall apart (forged rods / pistons / cams / etc)?

Also on anoter side note, besides the necessity of a new clutch that can hold this amount of power, will the transmission need to be beefed up? Most of the projects i have dealt with are no more than 300hp, and I didn't have to modify the transmission at all.

Don't flame too hard, i've just been introduced to the nissan world.

shaban

Just change certain components of the transmission and you should be fine. Pilot Bearing, Throw Out Bearing, Clutch, Flywheel, etc.
And the engine should hold up fine as long as you have a good tune.

airman

alright, thanks. what about my main question though?

jramosthe1st!

iTrader: (1)

when dealing with actual performance products you always want to buy products from a reputable establishment. i'd recommended that you defiantly buy a set of name brand springs and retainers. that is assuming they are necessary, depending on how big of a cam we're talking about the oem springs may be suitable. this is a question that should be addressed after you've chosen the cams. often the manufacture of the cam will state whether new springs and retainers are needed or just recommended.

also if you plan on turbocharging the engine you should get a set of cams intended for a turbo charged engine. and depending of how big of a cam you decide to get you may need additional machine work to be done on the cam towers.

airman

as stated in the OP, i would be going with a set of 264 or 272s.

cam towers?

and that's new to me, what's the difference between a cam made for a ka24det and one made for a ka24de?

jramosthe1st!

iTrader: (1)

journal/tower, bearing/caps same thing. depending on the manufacture and profile you may or may not need to replace the springs, retainers and additional head work. it's something that you should ask when buying the cams. although generally speaking most "street" or "stage I" cams tend to be just straight bolt on cams. it's the "strip" and "competition" profiles that tend to require additional work. again, this is something that you should ask a representative before buying either or so you have a good idea of just how much money will really be needed.

as for the difference between na and turbo cams, it's all in the profile. the turbo cam would have a different profile that would allow for either quicker spool allow better intake air flow or both. that's not to say that you can't use na cams on a ka-t. you'll just benefit more from cams designed for a turbo application.

fadedsilvia

i dunno if id bore 30 over

i thought i read sumwheres on here that going ne more than 20 over and the cylinder walls would be too thin, maybe im just imagining things? i dunno

and if your doin a full biuld then the piston u would prolly end up getting would prolly be made for a boosted engine as well

r u getting an engine and tranny now and building it then getting the car? or r u getting the car and driving it while biulding it?
if it was me id jus get an engine an tranny first and biuld the hell out of it, and ull prolly end up with well over 400whp, plus it waaaaaaaaaaaay easier and less space consuming to have to pull it out of a car an have the shell sittin around
but thats jus me

shaban

My old KA was .40 over for a good 10k miles before it blew.

airman

no way i would go .040 over. i'll probably be going with .020 over.