Author Topic: DOHC head - SOHC block conversion info.  (Read 9668 times)

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Offline Pure_Sincerity

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DOHC head - SOHC block conversion info.
« on: Jul 22, 2012, 04:40PM »
As some of you know, I'm underway of doing the twin cam conversion into my trx using the SOHC block.

Now I have everything for the conversion besides a new chip (contacting Ryan soon).

I've been cruising a few threads looking for info and there isn't much, in previous threads, jono says it wouldn't work, Colby said it will all bolt straight on, than SSS says its not as easy as Colby makes it out to be, that it works but shouldn't be done without experience etc etc

So what's the final verdict guys, DOHC head - SOHC block, what's the info ? I havnt picked up the other block yet to verify or test fit.
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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #1 on: Jul 23, 2012, 10:49AM »
Pwweeeaaaaassseeee  ::)
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Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #2 on: Jul 23, 2012, 01:45PM »
there isn't much info because we only know of 2 people that have done it to u12s. one guy from america did it to his stanza and from what i understand his motor didn't last long and then there is colby, who has been running his successfully for a while now.

from what i understand you need to fabricate a new timing chain cover, i don't think the stock ka24de one fits. i imagine you need a double chain sproket in the bottom end if you're running a double chain setup. if that fits the sohc block i don't know.

if i remember correctly colby had some issue with a distributor or coil or similar? obviously check with him. there is also wiring you need to change.

i would say though if you can, get as much info as you can from colby. he's done the swap so he knows what's going on.

or check with the 240sx forums. searching ka24 sohc to dohc swap on google comes up with results. you'd have to sift through the ones that have just changed the head to the ones that have changed the whole motor.
« Last Edit: Jul 23, 2012, 01:47PM by noss »

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Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #3 on: Jul 23, 2012, 01:53PM »
oh and for what its worth, i'd probably suggest it is wiser to get a full u13 front cut, swap in the ka24de in its complete form and put sohc pistons in it for the compression ratio rise.

get yourself a nistune board installed in the u13 ecu and i'll come and tune it for you.

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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #4 on: Jul 23, 2012, 04:35PM »
Well Colby did a full de transplant, block and all, than installed SOHC pistons in the de block.

It's only a double setup in the top, double linked chain running over the 2 cam gears than down to a double sprocket which than a second single chain runs from that down to the crank so that's all fine with no modding needed.

As for the dizzy and injectors, I am aware that they have to be re wired. Apart from that I'm pretty damn sure that's it, everything else should bolt straight on including the timing chain cover.

Also for the u13 ecu that all has to be wired into the loom also, it's 10000x easier to get a DOHC chip through you than somehow sort out the compression issue.
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Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #5 on: Jul 24, 2012, 11:11AM »
i'll be able to sort out the extra fuel required due to the higher compression no problem. i think its a lot more involved that simply plugging in the DE ecu though.

i would still suggest run a full DE with E pistons, changing the whole lot over, loom an all, sounds shitloads easier to me than trying to mate up a DE ecu and head to E loom and sensors. i might be wrong though, but i just see headache all over.

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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #6 on: Jul 24, 2012, 12:44PM »
Lol, I'm not touching a DE ecu. What what I've read and understand is that I can just use an e ecu with the de fuel maps on a chip.

Wiring the injectors and dizzy is easy. We re wired a whole sr to suit gtir loom a few weeks back in my brothers car.

Not to mention the block I'm picking up is completely rebuilt and just shy of a 2.5 Litre.

I dont see a headache.

Just to re quote this, I'm running a SOHC ecu not a DOHC. Lol
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Offline Colby

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Re: DOHC head - SOHC block conversion info.
« Reply #7 on: Jul 25, 2012, 09:56AM »
Well Colby did a full de transplant, block and all, than installed SOHC pistons in the de block.
Guilty as charged.
I did the full transplant and used the DE ecu.  I tried wiring in the E ecu, but it was WAY harder.  the E uses different idle control valves, all the vacuum relays dont exist in DE, some other sensors at the back are in different positions so the loom needs to be extended for those, the oil pressure sensor doesnt even fit on the DE (the throttle body gets in the way), the starter loom is different, and as noted the dizzy and injectors are different.
On the bright side I may still have the spare DE mapped chip for the E ecu.

doing the DE ecu only requires two big plugs to be changed.  Then use a nistune board if you plan on running bigger MAF or other fuel ratio upgrades.  I'm still running the stock ecu, even with the higher compression.  I have the fuel pressure tuned using a manual adjustable regulator to ensure it runs smoothly.

Nobody mentioned SleepaTI DE head swap.  He would be the one to talk to about the timing chain and related covers, but he isnt here much now, and no longer has the car (never seen the guy that bought it).  He also used the E loom, combined with nistune realtime chip, so it can be done... I just feel its much easier to do the full swap.  Either way you'll want a nistune board to open up to a proper range of mods, and then you wont have to rely on Noss to retune stuff for you... you can do it yourself!

Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #8 on: Jul 25, 2012, 11:29AM »
http://www.antrx.com/smf/index.php/topic,9895.4;msg=164486
just fixed your link, you linked report to moderator - noss

^^ That has also given me alot of valuable information.

As it is, I have everything needed for the conversion but after I get the de head reco and pick up the 2.5 liter block, it will be getting built outside the car, givin me and the old man more room to play, not only that, we can see everything.

I also finally saw the video of sleepas ka24det build video and got fucking damn that's fast, I think mine may be turbo built in 2 years when I hit opens, just lower the compression.

But in the mean time, I will stick to the SOHC ecu with a de tuned chip to the j30 maf and obvious fuel upgrades.

Soni found out we can eliminate most of the vacuume lines which is good, now what's the problems with the sensors col ? Just need to extend the loom to fit ? Or different plugs needed ?

Anywho, seems only the timing chain cover is the big issue, but that will be worked out when it comes into play. When underway, my project thread will be pic happy for you guys with all the information needed. Project high comp ka25de with other various mods, let's do it. Pics of De head etc etc will be up in my thread later tonight or tomorrow.
« Last Edit: Jul 25, 2012, 12:25PM by noss »
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Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #9 on: Jul 25, 2012, 12:22PM »
Lol, I'm not touching a DE ecu. What what I've read and understand is that I can just use an e ecu with the de fuel maps on a chip.

Wiring the injectors and dizzy is easy. We re wired a whole sr to suit gtir loom a few weeks back in my brothers car.

Not to mention the block I'm picking up is completely rebuilt and just shy of a 2.5 Litre.

I dont see a headache.

Just to re quote this, I'm running a SOHC ecu not a DOHC. Lol

i have no problem tuning that. what i am saying is the install. as colby has said, a full swap would be easier for the install. but then i think i'm overcomplicating it all. you're changing a head, intake manifold, exhaust manifold, distributor and timing kit. you only have to worry about sensors and what not on the head. so distributor, idle control, throttle body etc. everything south of the head will be sohc kit, so keep the sohc ecu. just check the impedance of the injectors between sohc and dohc, i can't remember if they're different or not.

as for the tune, i can tell you now that dohc maps are leaner than sohc maps and timing is different as well. in simple terms, this is because of different multipliers for the maps between the two ecus. running a dohc map in sohc ecu, it is the sohc ecu doing the calculations.

eg.

80% throttle, 4000rpm sohc ecu might have a value of 92
80% throttle, 4000rpm dohc ecu might have a value of 36

now, to over simplify it for point of an example, we'll say we're wanting to achieve an air fuel ratio of 13.5:1 and you achieve that with the sohc ecu and it's value of 92. 13.5:1 being a reasonably optimal afr for performance in a non turbo vehicle

so for the purpose of this, we'll call 92 100% of 13.5:1, what does the dohc map give us in the sohc ecu?

36 / 92 = 39%

keeping in mind it is air:fuel so higher number:1 = leaner, lower number:1 = richer

39% of 13.5:1 = 34.6:1 @ 80% throttle and 4000rpm = very bad.

for those that don't know a lot about afr's, you want 12.2:1 for a safe performance turbo tune and 13.2:1 for a safe n/a tune. all the people that tune turbos to 10:1 in my opinion just aren't doing their job right. stoichiometric (most efficient use of fuel) is 14.7:1 a lot of cars will 'lean burn' on cruise, which is around the 15:1 area. if you start getting leaner than 15:1 you should really be reconsidering what you're doing.

obviously an extreme example and not using the real numbers, just numbers i have plucked out of the air, although i do know the high load/high rev area of the sohc map to be in that 80-90 area. i could pull up the exact values for you between a tuned (stage 3) antrx chip which i know run at that 13.5:1 range and a stock dohc map if you like.

Either way you'll want a nistune board to open up to a proper range of mods, and then you wont have to rely on Noss to retune stuff for you... you can do it yourself!

there is no more that can be done on nistune that can't be done without nistune. nistune just puts it all in one neat little package so you don't have to buy this and that piece of kit to realtime tune, program chips etc. essentially all nistune is is an emulator that you plug in to your ecu and you have software that only works with that board. once a tune is done though, you shouldn't have to re-tune. unless of course you're have a turbo, then any change you make to boost, exhaust, intercooler piping routes etc, you might want to assess your tune.

i find that people that have access to nistune tend to attempt to 'tune out' stuff that is simply maintenance. i.e. unstable idle due to an intake leak. people for some reason think 'oh shit my tune is out i need to fix it' which is just plain wrong. not saying that you have done this colby, but it is what i have experienced with various people in the past.

the other annoyance is people that tune without a wideband, but whatever.

this is also not me trying to get money off aaron. it is just my opinion but $100 for a tune that you're never going to have to change anyway vs $600+ to get nistune running (that is pricing board, cable, software licence) is a no brainer cost wise.

for a sohc ecu like the ka24e that runs an 8bit eprom, if you want realtime tuning all the time (i.e. without needing me), i would suggest buying an eprom emulator ($200) and using romeditor before bothering with nistune.

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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #10 on: Jul 25, 2012, 03:48PM »
Umm, me no understand, DERKA DERKA, can I please just have a chip with the DOHC maps for the SOHC ecu capable of running the higher comp ? Lol
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Offline SleepaTi

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Re: DOHC head - SOHC block conversion info.
« Reply #11 on: Jul 25, 2012, 10:00PM »
nistune is more "tune-able"

with a chip you get what you get, as in you can't make fine adjustments as with nistune

i've done it all before, have a look at my sig.. KA24DET ftw
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Re: DOHC head - SOHC block conversion info.
« Reply #12 on: Jul 25, 2012, 10:03PM »
all you need is an altima (bluebird) oil pump & timing chain kit & a fsm for bluebird & pinty
it all bolts up the same....
the ONLY difference between the blocks is the DE has oil squirters & bigger sump bolts
NO! it's NOT a fucking SR20!!

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Re: DOHC head - SOHC block conversion info.
« Reply #13 on: Jul 25, 2012, 11:03PM »
Why the de oil pump ? Can I just use the e pump ?
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Offline SleepaTi

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Re: DOHC head - SOHC block conversion info.
« Reply #14 on: Jul 26, 2012, 01:01AM »
less bullshit & mucking around modifying head gaskets

http://www.ebay.com.au/itm/93-97-2-4L-Nissan-Altima-KA24DE-Timing-Chain-Oil-Pump-/280730270386?pt=Motors_Car_Truck_Parts_Accessories&hash=item415cd3fab2

while on ebay, try looking for a cheap u13, it'll give you everything you'll need

i've bought 3 already, 2 for $500 & 1 for $300
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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #15 on: Jul 26, 2012, 01:33AM »
Cheers dude, but after purchasing the timing chain and oil pump I have everything ready to bolt on and go.

Can't wait.
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Offline Pure_Sincerity

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Re: DOHC head - SOHC block conversion info.
« Reply #16 on: Jul 26, 2012, 01:46AM »
Actually, all the oil pumps say they are an 89mm bore, would that have anything to do with the cylinder bore ? Because this block is an 89.5mm bore...
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Re: DOHC head - SOHC block conversion info.
« Reply #17 on: Jul 26, 2012, 07:17AM »
its just a reference they use
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Re: DOHC head - SOHC block conversion info.
« Reply #18 on: Jul 26, 2012, 09:44AM »
Fuck yeah, will be done sooner than expected, cheers for the info guys.
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Offline Colby

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Re: DOHC head - SOHC block conversion info.
« Reply #19 on: Jul 26, 2012, 10:14AM »
i find that people that have access to nistune tend to attempt to 'tune out' stuff that is simply maintenance. i.e. unstable idle due to an intake leak. people for some reason think 'oh shit my tune is out i need to fix it' which is just plain wrong. not saying that you have done this colby, but it is what i have experienced with various people in the past.

lol I can't have done this, I'm still on a stock ECU  :P  basically I can't justify spending $500 for nistune when my car runs fine at the moment. I personally wouldnt get nistune unless going forced induction.

Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #20 on: Jul 26, 2012, 01:51PM »
lol I can't have done this, I'm still on a stock ECU  :P  basically I can't justify spending $500 for nistune when my car runs fine at the moment. I personally wouldnt get nistune unless going forced induction.


lol not saying you did. but i have seriously come across people that have. worse, doing it without wideband, thinking that an afr display from jaycar on their narrowband was sufficient.

nistune is more "tune-able"

with a chip you get what you get, as in you can't make fine adjustments as with nistune

i've done it all before, have a look at my sig.. KA24DET ftw

nistune has the same tunability of doing it without nistune. i've used a number of ecu tuning software packages and they're all pretty much the same. the advantage though of nistune is that for people that just want to jump straight into it, all the maps are there for them, pre-configured (provided that the nistune guys have taken the time to find all the maps) where as if you do it yourself, well, you have to find those maps yourself and most people are too lazy to learn how. nistune is nothing special. it is a pair of emulators on a daughterboard in a one stop package. you're still tuning an OEM ecu, you have the exact same level of tunability.
« Last Edit: Jul 26, 2012, 01:53PM by noss »

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Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #21 on: Jul 26, 2012, 01:55PM »
Umm, me no understand, DERKA DERKA, can I please just have a chip with the DOHC maps for the SOHC ecu capable of running the higher comp ? Lol

yeh no worries, i was just trying to explain stuff. i will give you a tuned chip for what you need.

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Offline Colby

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Re: DOHC head - SOHC block conversion info.
« Reply #22 on: Jul 26, 2012, 02:52PM »
maybe off topic... but I would like to see a consult readout for my ipad/iphone (or similar android device).  It would be sweet to have the PLMS program on the screen, maybe switch from power to economy map at the touch of the screen, plus view all the realtime readouts (temps, speeds etc).
You should get onto that one noss  ;) I'll even donate my idea.

Offline noss

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Re: DOHC head - SOHC block conversion info.
« Reply #23 on: Jul 26, 2012, 05:42PM »
i have a system that can switch a single map on  the one chip. if you had a DE ecu with 2 chips on a daughterboard it would be the same thing but with the switching device installed twice.

there is an obd package on android called torque and another called obdkey, but no ecu flashing ability.

there is also an app for android called 'nikoz nissan diagnostics' or something like that which hooks up to nissan consult via bluetooth.

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Re: DOHC head - SOHC block conversion info.
« Reply #24 on: Jul 31, 2012, 11:26PM »
I still fail to understand why the de oil pump is required in the conversion ? Can someone explain ? How does the oil pump have anything to do with the head gasket ?
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Offline SleepaTi

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Re: DOHC head - SOHC block conversion info.
« Reply #25 on: Aug 1, 2012, 12:00AM »
the top chain cover on the de head has a different shape to the E so you need the de oil pump (& de head gasket)


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Re: DOHC head - SOHC block conversion info. CONFIRMED.
« Reply #26 on: Aug 18, 2012, 10:37AM »
Confirmed, DOHC head bolts straight onto the SOHC block.

Need. DOHC head, dizzy, injectors, fuel rail, intake, timing cover, timing chain, a tune through Ryan for a SOHC ecu or nistune, modify loom slightly, re wire injectors and dizzy, extend loom for other sensors, extractors and ignition leads.

Benefits, slightly higher revving, 16kw, 14nm torque and high compression ratio, oh and no fuxking around with rocker arms etc, they don't have none ^_^
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Re: DOHC head - SOHC block conversion info.
« Reply #27 on: Aug 18, 2012, 02:49PM »
told ya :P
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Re: DOHC head - SOHC block conversion info.
« Reply #28 on: Aug 18, 2012, 09:32PM »
Benefits, slightly higher revving,

Still limited by the rotating assembly in the SOHC block; however the engine shouldn't feel so asthmatic higher up in the rev range.

Quote
16kw, 14nm torque and high compression ratio,

This will depend on your tune. A good tune with that compression should yield a little more.

Quote
oh and no fuxking around with rocker arms etc, they don't have none ^_^

Easier to do cams with though in the SOHC.

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Re: DOHC head - SOHC block conversion info.
« Reply #29 on: Aug 18, 2012, 11:21PM »


limited by the rotating assembly in the SOHC block?

are you talking about the crank & rods? they are the same (part number) to any ka24.

crank...... i used an E crank in my DET
http://www.nissanpartszone.com/Page_Product/PartsFits.aspx?partNumber=12200-30R00

rods........
http://www.nissanpartszone.com/Page_Product/PartsFits.aspx?partNumber=12100-53F01
NO! it's NOT a fucking SR20!!