Cheapest NA Horse Power

[Zemus]

I just am about to buy a KA24DE from Wheresmytofu, and he is giving me 92mm 10:1 comp pistons (stock is 90mm). So their for i will be tearing the block apart and hoping to build it up from their.

Anyways getting back to my real question. while im in their, or while i have the engine apart, what can i add/alter for some cheap HP.

I already have the pistons which are a good start, and may give me possably 10 HP if im lucky. Any suggestions?

[Zemus]

*bump*

[NiteKids]

Well you see what your talking about isn't quite that simple...

[AceInHole]

Since you're rebuilding, while the heads off you can have the valves reseated, or the head ported and polished. It's not the cheapest thing to do but since you're down in the engine it might be more practical to do it then rather than later. If you're really "daring" you can do it yourself. Valve seats can be done by hand, as well as the port and polish.

[Zemus]

My friend was telling me he has a tool for porting, and i hear polishing isent that bad it just takes time, that sounds good, anything else.

Note: Thanks for the imput :)

[d240t2]

Stock bore is 89mm, not 90mm. Factory overbore sizes are 89.5mm and 90mm. 92mm is a little big...are you sure that is the correct size?

And stock compression is 9.5:1...if you are going to change compression...why not at least go up to 11.0:1. SOHC KA pistons can be used to raise that compression.

Best bang for the buck mods on a stock KA are intake, exhaust, JWT ECU, S13 cams, in no specific order.

Dennis

[Zemus]

Originally posted by d240t2
Stock bore is 89mm, not 90mm. Factory overbore sizes are 89.5mm and 90mm. 92mm is a little big...are you sure that is the correct size?

And stock compression is 9.5:1...if you are going to change compression...why not at least go up to 11.0:1. SOHC KA pistons can be used to raise that compression.

Best bang for the buck mods on a stock KA are intake, exhaust, JWT ECU, S13 cams, in no specific order.

Dennis

Your wrong in a few way, Well mainly the SOHC pistons, their 9:1 or somthing like that, and thats lower than stock, everyone seems to not know that.. and S13 cams? you mean out of a sr20? And these pistons are out of a Japanise 4.5l v8 engine and they will work, their OEM and i get them for free, so its worth it,

[sykikchimp]

the SOHC pistons are 9.1:1 in the SOHC engine.. because of the flat top (I think) in the DOHC they make 11.1:1. Could eb due to wrist pin placement, but more than likely just the piston top.

He said thats large because if you overbore the engine that much then you will run out of cylinder wall.

when he says "s13 cams" sure he means the "Hot" cams from the early s13 with 248 duration.


listen to dennis.. he knows what he's talking about.

Do you have specs for those pistons your buying? whne you say 92mm I think you mean diameter right? are they flat top?

[d240t2]

No.

SOHC pistons are 9.1:1 or 8.6:1, however, the head design on the DOHC motor is different. When you put SOHC pistons in the DOHC motor, it raises the compression. You actually have to mill them down to lower the compression to 11:1.

And S13 cams...I was referring to KA cams. S13 KA cams are more aggressive than S14 cams...and S13 exhaust cams are more aggressive than S14 cams.

Make sure you know what you are talking about before you claim that "everyone knows that".

I understand the use of free pistons...but if it encroaches on the cooling channels in the block...or leads to very thin cylinder walls...then you'll have problems. That is the kind of thing you will want to check before overboring that much and planning on using those pistons. I don't know if the KA cylinder walls are or aren't thick enough to withstand a 3mm overbore...but I certainly would check before doing it.

Dennis

[AceInHole]

And S13 cams...I was referring to KA cams. S13 KA cams are more aggressive than S14 cams...and S13 exhaust cams are more aggressive than S14 cams.

I think you meant to say S13 exhaust cams are more agressive than S13 intake cams, which are more aggressive than both S14 cams... and that ideally (besides getting JWT cams or something) you'd want 2 S13 exhaust cams, one pinned as an intake cam.

[d240t2]

Right...although what I did say is technically correct. S13 exhaust cams are better than S13 intake cams. S13 intake cams are better than S14 intake cams. S14 intake cams are the same as S14 exhaust cams. S13 exhaust cams are better than any S14 cam. You get the point.

And there are ways around repinning the S13 exhaust cam for use as an intake cam...works great for us turbo folks.

Dennis

[LanceS13]

And whose to say those 10.0:1 pistons out of a 4.5L V8 will be anywhere near 10.0:1 when under the DOHC KA head? Or if they even have sufficient valve relief.

[d240t2]

Originally posted by LanceS13
And whose to say those 10.0:1 pistons out of a 4.5L V8 will be anywhere near 10.0:1 when under the DOHC KA head? Or if they even have sufficient valve relief.

Exactly.

They could be 5:1 compression ratio in the DOHC motor...or they could be 15:1.

Dennis

[AceInHole]

Originally posted by d240t2
And there are ways around repinning the S13 exhaust cam for use as an intake cam...works great for us turbo folks.

JWT adjustable cam gear??

[DuffMan]

I hope those are aqua pistons, because at 92mm bore, they are going to be swimming in water.

:eek:

[d240t2]

Originally posted by AceInHole
JWT adjustable cam gear??

;)

I have 2 S13 exhaust cams...no adjustable cam gears.

Can't spill all the secrets in public...although, I think I have told this secret on a message board before.

Dennis

[AceInHole]

bah..... PM me or something!! :eek:

[Zemus]

Sorry Dennis, i have just been getting people saying that the SOHC pistons are higher in the sohc, thats why i said "doesnt anyone know"

Also this is a s13 cam from a 91-93 so it already has the cams you speak of.

Also if i were to put in SOHC pistons, (note i have a sohc currently)
do you know what the HP gain would be. I would really like to use the VH45DE pistons, i wonder what comp they would run, i hear they would work

thanks
-Matt

p.s. sorry for my ignorance

[misnomer]

uh. . . .

You don't just take pistons from another car, drop them into yours, and expect things to run hunky dorey. the SOHC pistons work because they are for the same block, due to their design or connection point to the rod, it just happens to raise the compression if you use them in the DOHC version OF THE SAME MOTOR.

Pistons for other motors will need to have the same diamter, and close enough connection to the rod in order to be feasable. Your BEST bet in pistons would be to just pick up some designed for your motor.


And d240t2, what's with the secrecy about your exhaust cam installation? Any reason you can't enlighten the rest of us? :-)

[d240t2]

Yeah...I worked hard to figure it out.

How about this...we'll play a critical thinking game. All we did was think about it, take some measurements...think some more, and not be afraid to try something new that we knew would work.

So go for it...I won't even make anyone take any measurements. I'll even answer questions...but its up to you guys to figure it out.

I am not trying to hide it...I think I'll tell eventually...but we all could use a little critical thinking practice sometimes.

This sounds like it'll be entertaining enough to make it worth me telling in the end.

As for the SOHC pistons...raising the compression to 11.0:1 really doesn't gain all that much. Not enough people have really done it to tell...but I'd say maybe 10-15rwhp from my observations of one car with them, his mods, and comparisons to other cars with similar mods.

Dennis

[Zemus]

Originally posted by d240t2
Yeah...I worked hard to figure it out.

How about this...we'll play a critical thinking game. All we did was think about it, take some measurements...think some more, and not be afraid to try something new that we knew would work.

So go for it...I won't even make anyone take any measurements. I'll even answer questions...but its up to you guys to figure it out.

I am not trying to hide it...I think I'll tell eventually...but we all could use a little critical thinking practice sometimes.

This sounds like it'll be entertaining enough to make it worth me telling in the end.

As for the SOHC pistons...raising the compression to 11.0:1 really doesn't gain all that much. Not enough people have really done it to tell...but I'd say maybe 10-15rwhp from my observations of one car with them, his mods, and comparisons to other cars with similar mods.

Dennis Thanks, 1 more question, what all has to be done to the SOHC pistons so i can put them in the dohc

[mrdirty]

Originally posted by d240t2
....
Can't spill all the secrets in public...
you posted just to tell everyone that you won't post.....dick.:mad:

Note: No one gives a $hit about your "secret", do u expect ppl to BEG or something?

Either post info or don't, but don't come on here and be an arrogant a$$hole.

[Nismos14]

Originally posted by mrdirty
you posted just to tell everyone that you won't post.....dick.:mad:

Note: No one gives a $hit about your "secret", do u expect ppl to BEG or something?

Either post info or don't, but don't come on here and be an arrogant a$$hole.


he wasn't being arrogant, i didnt take offense to anything he said, BUT i did take offense to what you said :D that was harsh, he definately didnt deserve that, and furthermore, he's just making u learn more, u just want a quick fix, well by learning more, u'll get alot more out of it, so y bitch about it?

[kandyflip445]

Hey d240t2. Any hints? I haven't gotten to look at a OHC engine apart yet. I'd like to try and figure it out but like I said I haven't seen one apart! :p

[mrdirty]

Originally posted by Nismos14
....he's just making u learn more, u just want a quick fix, well by learning more, u'll get alot more out of it, so y bitch about it?

If he wants to pass on info then great, explain to me how he's teaching u anything w/ comments like:
"I am not trying to hide it...I think I'll tell eventually...."


but hey, u want to play head games fine; I for one don't have the time to sit on a forum and play "guess what I'm thinking"

and yeah, it was a bit harsh (probably too harsh) but this is not the way to educate; this is a way to get attention.

[projectsilvia1]

the SOHC pistons work because they are for the same block, due to their design or connection point to the rod, it just happens to raise the compression if you use them in the DOHC version OF THE SAME MOTOR.

the sohc and the dohc are not the same block at all!!!!
just thought you should know that neither are the heads
Mike

[AceInHole]

I'm wondering if all he did was just rotate the cam around a certain amount of teeth. I'll be checking my valve lifter clearances tomorrow or tuesday so I'll see how close it would be. I'm willing to bet it won't be off by a few degrees or so. From a quick look at some of the pics online, looks like the cam sprocket has like 20 teeth, so it's 18 degrees per tooth, so if that's right you'd have a +/- 9 degree range that the cam might fall into. Obviously you'd like it to be near 0, or exactly the same....

[Zemus]

Anyone else have any information that would be helpful? I would love to hear what you have got to say, cuz im really up for doing this.

[d240t2]

Originally posted by AceInHole
I'm wondering if all he did was just rotate the cam around a certain amount of teeth. I'll be checking my valve lifter clearances tomorrow or tuesday so I'll see how close it would be. I'm willing to bet it won't be off by a few degrees or so. From a quick look at some of the pics online, looks like the cam sprocket has like 20 teeth, so it's 18 degrees per tooth, so if that's right you'd have a +/- 9 degree range that the cam might fall into. Obviously you'd like it to be near 0, or exactly the same....

JWT adjustable cam gears only adjust in 2.5 degree increments.

What makes a good set of turbo cams?

What is the actual difference between the intake and exhaust cams that causes you to "have to repin" the exhaust for use as an intake. (Hint: Valve lifter clearance isn't what you need to check...the difference in location of the cam lobe in relation to the pin is what you need to check to do what you are talking about.)

Give a man a fish, feed him for a day. Teach a man to fish, feed him for life.

If you think I am just a prick, who cares. I have been more than forthcoming with a whole lot of information in the 240SX world...a whole lot of stuff that I spend my hard-earned money and time working on...that I gave away so ungrateful people like you could know what the KA+Ts stock bottom end potential was...or what you had to do to get the ebrake to work with Z32 rear brakes, etc.

Maybe I get to try and help you guys think on here every once in a while...if I get tired of giving all my work away. I mean...I didn't get the answer to this solution handed to me...my fairy godmother didn't bring it to me. I did exactly what I am asking you to do here. Besides, you aren't ever going to do the cam swap anyways, so what do you care?

It isn't that difficult...Jason and I maybe spent half an hour talking about it...and then did some measurements, a little bit of research, and went ahead and did it. AceInHole will get it, no thanks to you, mrdirty.

Dennis

[d240t2]

Also don't forget...360 degrees/20 = 18 degrees of cam rotation...but cam rotation is half that of crank rotation...and cam specs are generally given as duration (like 242) out of 720 total degrees.

[mrdirty]

Originally posted by d240t2
I have been more than forthcoming with a whole lot of information in the 240SX world... I get tired of giving all my work away.

Point taken, but not everyone has the time, skills, experience or money to do the things you've done. I'm pretty sure you're not losing anything by sharing your experiences but I understand that u just want more ppl to make similar discoveries.

I did totally over-react; I apologize. I guess I get a bit over sensitive to ppl dangling bits of knowledge in front of ppl having spent pretty much 14hrs a day w/ engineers; it gets frustrating.

So yeah, I was wrong; sorry :)