Using S13 parts on an S14 DOHC swap...why?

[Clawhammer]

I tried posting in the "right" forum...let it stew for a few days and nothing. So don't hate me for appealing to the traffic.

I've done lots of searching and found that I need various S13 DOHC parts (such as ECU, harness, MAF, exhaust manifold, etc). None of my searching however really explains as to WHY I need these things? It makes sense to me, intuitively, that since I have the motor, and S14 versions of all the above items, there shouldn't be any problems? What am I missing here? Thanks.

[martins_240sx]

???obd1 and obd2??? Just a thought

[Clawhammer]

Yeah, so if I use all OBD2 stuff, where's the problem?

[White Comet]

im kinda confused on how u worded the question. are u saying u have an s13 ka and wanna know why the s14 ka parts wont work? im probably way off

[MoSinister]

I'm guessing he's swapped a DE into a pignose...

[Clawhammer]

I have an S14 KA that I will be swapping in the very near future. In order to use the S14 KA I have to use parts of the S13 dual cam...as martin mentioned, probably do to with OBD1 and 2....however, I do not understand why it matters if I use ALL OBD2 stuff.

[White Comet]

oh i c, yeah good question, cant help on that one

[Clawhammer]

Someone must know! I've read like 7 didn't write-ups on the swap and they all say we have to do it. No one explains why.

[White Comet]

that doesnt make any sense to me. i can understand some wiring needing to be done since its between 2 dif chassis, but i dont see why it wouldnt work if u used teh s14 everything. its just like any other engine swap, u dont keep the ecu when u do an sr swap

[DjPantsSpecR]

you do it the way we've written it up because thats how we've done it, thats how it WORKS, and because it simplifies things.

i'm about to run to another final, or i'd stay and explain...

just incase you need cliff notes.... the MINIMUM to run an s14 KA with an S13 harness and ECU is s13 distributor, s13 upper intake manifold SENSORS, lower s13 intake plenum with tps. S14 downpipe or entire s13 header assembly. S13 MAF.

if you want to keep AC the bracket of the compressor you are using must match the year of the compressor. i cant remember about PS, but i always just kept the pump connected and out of the way.

So, its really not that much, and the reason to use the s14 upper manifold is to rid the SCV and all the vac lines associated with it on the back of the s13 head.

i really dont have time, if you have specific questions ask

[CMG]

So it sounds like by using all the s13 parts mentioned it will kind of convert it to obdI so there's no compatibility issues.

[White Comet]

i can see the need to convert to obd1 and stuff but some things throw me off like using the s13 exhaust manifold

[martins_240sx]

I think the sensor might be issues since the obd1 and 2 might read at different ranges?... I would think that if you keep it all exclusive to one ,obd1 or 2, you shouldnt have any problems

[eazye2000]

You're gonna need what 'DjPantsSpecR' said. It's just what he said.

I have a '95 240sx that has OBDI. Thank god. But what I'm getting at, is it's different. It's different from S13 OBDI, and a little closer to the S14 OBDII.

So just source some of the necessary S13 stuff and you'll be good to go.

Side Note: I'm swapping my S14's OBDI over to the S13 ECU, harness, motor, and stuff because it's much simpler.

[Clawhammer]

Cool, but why does it simplify things? Seems to me simplying things would be putting everything that goes with the motor in, not mixing and matching parts.

[CMG]

Parts compatibility

[Clawhammer]

Compatability with what?

I guess I just need to wait for DJ to come home and do some explaining. Good luck with the finals!

[driftneil]

Compatability with what?

I guess I just need to wait for DJ to come home and do some explaining. Good luck with the finals!

Compatability from sensors to computer to motor. It's the way it is, Without the s13 ecu it wouldnt read the s13 signals from the sensors....but obviously the output signal are the same. Also like someone else said, the 95 was the transition from obd1 to obd2 so it has it's problems.

[White Comet]

Compatability from sensors to computer to motor. It's the way it is, Without the s13 ecu it wouldnt read the s13 signals from the sensors....but obviously the output signal are the same. Also like someone else said, the 95 was the transition from obd1 to obd2 so it has it's problems.

yeah but if u used s14 sensors, ecu and motor, there shouldnt be a prob.........right?

[mrgreeneyes]

just use the s13 parts... you are putting the motor in an s13, so why not use the s13 goodies? id use the upper intake mani off the s14 for deleting the SCV's and crap... but you will need the s13 distro and ish if you use s13 ecu...

[White Comet]

^ true, but i dont see why it wouldnt work w/ s14 stuff

[mrgreeneyes]

it will work, but not in the same manner that was intended for an s13ka. my suggestion was to make a hybrid... but why would you want an obd2 ecu in an obd0 car?

[White Comet]

earlier s14 ka are obd1, but yeah i wouldnt wanna go and convert to obd2 or anything

[Clawhammer]

Oh I'm not trying to do it differently lol. I'm just trying to figure out WHY we do it. And as you can see by this thread full of people that don't know either, we just do it because that's what everyone else does...now I know why you all have 240's

Apparently I'm the only one that actually cares about why. Atleast I'm not the only one who is confused by an S14 KA with all S14 sensors and ECU having issues sensing...itself? (Thanks WC)

[White Comet]

Atleast I'm not the only one who is confused by an S14 KA with all S14 sensors and ECU having issues sensing...itself? (Thanks WC)

no prob, any time you want help being confused on something, just let me know

[DjPantsSpecR]

alright, and i think the two finals went alright, thank you sir.

um, well, i swapped an OBDi 95 motor in my 92. I also have an OBDii 96 and despite being OBDi, many of the intake manifold sensors are different. S13 iacv, CTS, and gauge CTS are all different. I think the TPS's are as well, but i dont recall.

SO, in order to keep things simplified we use s13 lower intake manifold included with its sensors. This allows you to run idle air control valve. You'll also notice that S14 lower intake manifolds want to reroute your coolant lines to useless places. Thats why we just use the stock lower s13 manifold.

Using the S14 upper manifold (with the s13 CTS sensors) is advantageous because it gets rid of the SCVs. Chances are if you have an s13 you've already ditched the black box on the driver side, this is called the AAIV.

Now, the s13 has a vacuum gallery on the back of the head with solenoids to run both of these devices. S14's dont have this. If you've ever put an s13 intake manifold on you know how big of a pain in the *** it is to deal with all these vac lines. Its nice to be able to ditch them all. This gains you some free ponies and helps clean things up.

you can use an s14 transmission on an s13, but not vice versa. S14 trannies have the CAS in the upper bellhousing, whereas S13s have the CAS in the dizzy. gotta swap speed sensors, and cut the collar off the tail, but thats it.

exhaust manifolds: S13s have a specific two piece header. So the upper part will only bolt to an s13 lower section. S14 exhaust manifolds have the different output, and while i cant verify this, it supposedly is common knowledge that an s14 exhaust manifold will bolt up to an SR downpipe. So if you have a turbo future, and a downpipe laying around you can just use the s14 exhaust mani. OBDi's use the single wire o2, while OBDiis use the three wire. you have to use the kind that your harness uses

ignition was already briefly covered. they are just SO different.

AC brackets are specific to the compressors. I cant remember about PS though. I know the brackets are unchanged however.

Supposedly S14 heads allow for higher compression than s13 heads, but im still skeptical until i see it for myself. valve covers are head specific too. for the same reason front upper timing chain covers are specific as well.

BUT, just to reiterate: if you have a complete S13, and a S14 short block, you can always make it work by bolting on the s13 manifolds.

lemme know if you need any more info

[White Comet]

you can use an s14 transmission on an s13, but not vice versa. S14 trannies have the CAS in the upper bellhousing, whereas S13s have the CAS in the dizzy. gotta swap speed sensors, and cut the collar off the tail, but thats it.

all good info but this is the only part i have a problem w/ ive been told multiple times and im pretty sure that the trannies are all the same from 89-98

[Clawhammer]

Thanks a lot DJ, that helps a lot.

I've also always heard that all trannies were the same. Weird.

[White Comet]

i searched and couldnt find any threads on it but i know if seen/heard it many times before.

[DjPantsSpecR]

well thats because they technically are..... kinda

s14 trannies are actually a bit longer due to this weird metal and rubber collar thing they put on at the tailshaft. Trust me i know.... you have to cut it off if you want to put an s14 transmission in your s13. it took me at least a half hour to figure out why i couldnt get my drivcveshaft to fit the first time.

and as stated before the only other difference besides the different speed sensors is that there is a Crank Angle Sensor in the top of the S14 bellhousing. If you wanted to put an s13 transmission in your s14 you would need to drill a hole to fit this.