You can't just put the DE head onto the E block without extensive machine work because they are different sizes. The DE head is slightly larger than the E head and will not be a bolt on affair.

 

everyone says stuff like that but the blocks are the same(meaning the headstuds are in the correct spot, and the headgaskets are identical iirc(mean coolant and oil passages are in the same spot). So how won't it fit?

I'll have a straight answer next time I go to NC.

All this does is bump compression, like putting SOHC pistons in a DOHC. high octane and proper timing adjustments would be needed.

 

everyone says stuff like that but the blocks are the same(meaning the headstuds are in the correct spot, and the headgaskets are identical iirc(mean coolant and oil passages are in the same spot). So how won't it fit?

I'll have a straight answer next time I go to NC.

All this does is bump compression, like putting SOHC pistons in a DOHC. high octane and proper timing adjustments would be needed.

either way, there will be more to it than bold on de head, time it and then drive it.

 

I'm going by research and NOT personal experience. It would be cool to see the exact work needed to make it fit.

 

Well if I did it it would be on my beat to hell beater and not my nice clean project chassis so...if it's a ton of work and the car will be out of commission longer than a weekend it isn't worth it.

 

Yeah it would be more cost efficeint to find a DOHC KA and swap it completely. And YES you can keep the tranny.

 

I'm not doing a swap on my beater. My 90 project had the twin cam swap and the engine and trans are still there, but the guy I bought it from took the wiring and ecu. The project is getting another twin and eventually a KA-T, but the beater will stay as stock as possible till it finally rusts in two.

 

Ok so from what I've been able to find out about this you have to use the DE head, front cover and upper chain, and the E lower chain...can anyone verify?:12dunno

 

no, the E doesnt have a "lower chain". It just has one single chain. You use the DOHC timing chains and tensioners.

 

Thanks for the clarification. I knew the E only had one chain so the lower chain thing made no sense to me. Would I have to use the DE harness and ecu or the one from the E?

 

no, as long as your using the ecu for the sensors its fine. i think the DOHC has a knock sensor and the sohc doesnt. as long as your sensors are filled in, it doest really matter.

and yeah its cheaper to just put SOHC pistons in your DOHC

 

Even if you went though with it I don't think it would last long under the extra compression. Your timing would have to be perfect or your valves are going to get smashed.

 

it would be just the same as anything else. the blocks are thesame. therefore your proposed swap is exactly the same as putting sohc pistons in your dohc. therefor, your going to have no bigger timing issues than if you were rebuilding any other ka

 

The DOHC head isn't familiar to the higher compression created by the SOHC pistons. You don't think this would create ware on the engine faster?

I guess with timing and a tune anything is possible.

 

it can handle higher compression just like it can handle 20psi...

 

exactimundo
its not the metal per say, its how well the motor is put together.

 

the head fits just fine, it bumps the compression to about 11.0-11.5/1 so you have to use premium, you also have to use the DE ECU cuz the injectors and all that are from the de so itd be best to swap harnesses, the knock sensor (on the DE head) will also help prevent detonation, also the distributor is diff on the DE, youll have to use the DE MAF sensor etc. etc., IIRC you use the timing chains off of the DE (the lower gear is the same I think and the "middle" gear is on the head). its doable and pretty bolt on xcept for the lower timing cover, you use the E one but you have to machine it (I think its cool to do it with a dremel if your decent using one) it just doesnt quite fit up right. I believe that when I read the thread about the guy who last did it on the NICO forums he said he got about 210-230 to the wheels on 91 gas without any other mods besides exhaust and such I believe, dont remember any other specifics tho.

IMO since you already have the car with all the parts you need and cant use the block anyway, if all you want is a daily driver with a little more spunk, (its probably more of a monster torque machine if done right with all the usual bolt-on goodies) I would go for it, I would actually do this if I wasnt set on more like 350 to the rear wheels with a turbo set-up (its pretty hard if not impossible to make a streetable all motor KA with that kind of power) any way, sorry for the long post but thats my 1.02

Edit: And no way would putting pistons in be cheaper than swapping heads, especially doing the work yourself, all you need for the head swap is the parts this guy already has, and a head gasket set/head bolt set, if you crack in to the bottom end youll need all new bearings, rings, the block will need to get honed, the head will have to come off anyway, youll have to pull the motor a Full gasket set etc. etc. Not even considering the parts difference your looking at 3X more labor time at LEAST (whether doing the work yourself or not), plus the special tools needed to put the block back to gether right (plastigauge, ring compressor, some way to heat the pistons and press the pins out and in) unless the car was overheated, no machine work is necessary to do the job right swapping heads, not so with swapping pistons, sure you can do it the ghetto way, but why risk it? if the block was good on the DE and the block/bottom end on the E was messed up somehow, I could see swapping pistons being woth it, but not with a broken DE block, and a perfectly fine E bottom end.

 

the head fits just fine, it bumps the compression to about 11.0-11.5/1
so you have to use premium, you also have to use the DE ECU cuz the injectors and all that are from the de so itd be best to swap harnesses, the knock sensor (on the DE head) will also help prevent detonation, also the distributor is diff on the DE, youll have to use the DE MAF sensor etc. etc., IIRC you use the timing chains off of the DE (the lower gear is the same I think and the "middle" gear is on the head). its doable and pretty bolt on xcept for the lower timing cover, you use the E one but you have to machine it (I think its cool to do it with a dremel if your decent using one) it just doesnt quite fit up right. I believe that when I read the thread about the guy who last did it on the NICO forums he said he got about 210-230 to the wheels on 91 gas without any other mods besides exhaust and such I believe, dont remember any other specifics tho.

IMO since you already have the car with all the parts you need and cant use the block anyway, if all you want is a daily driver with a little more spunk, (its probably more of a monster torque machine if done right with all the usual bolt-on goodies) I would go for it, I would actually do this if I wasnt set on more like 350 to the rear wheels with a turbo set-up (its pretty hard if not impossible to make a streetable all motor KA with that kind of power) any way, sorry for the long post but thats my 1.02

Edit: And no way would putting pistons in be cheaper than swapping heads, especially doing the work yourself, all you need for the head swap is the parts this guy already has, and a head gasket set/head bolt set, if you crack in to the bottom end youll need all new bearings, rings, the block will need to get honed, the head will have to come off anyway, youll have to pull the motor a Full gasket set etc. etc. Not even considering the parts difference your looking at 3X more labor time at LEAST (whether doing the work yourself or not), plus the special tools needed to put the block back to gether right (plastigauge, ring compressor, some way to heat the pistons and press the pins out and in) unless the car was overheated, no machine work is necessary to do the job right swapping heads, not so with swapping pistons, sure you can do it the ghetto way, but why risk it? if the block was good on the DE and the block/bottom end on the E was messed up somehow, I could see swapping pistons being woth it, but not with a broken DE block, and a perfectly fine E bottom end.

Since when did the DOHC head, Or any 240sx head have a knock sensor on it? :12dunno

 

Cool. I've gotta pull the head off the DE and see if it's still good or not. If it is I'm def gonna do this. I'll see if I can find the guy on NICO that did it. On my other car I'm def gonna do some kinda turbo engine, but like a said this is just the beater.

 

i dont think you can get like 90 whp with sohc pistons and exhaust

 

definitely not, derek greaser had to go with cams and itb's to make 220whp on a KA

 

Well that's good since this is the beater. Not looking for gobs of power there. Looking to pull the blown engine outta the project this weekend or maybe next. Trying to decide what powertrain I wanna do once I get the chassis cleaned up and time+money to do it. The project will likely sit idle for the next year.

 

I'm in the middle of rebuilding one out of two DOHC KA's, one is going to be my DD while I build the other up to a KA-T.

So far I have removed the secondary butterflies from the intake, and since I have my engine torn apart ready to be slapped back together I was thinking of taking my buddy's spare set of SOHD pistons, get new rings for them and throwing them in my engine, I was also thinking about doing the double exhaust cam thing.....

What are my pros and cons, should I do all three?

My main problem that's putting me on hold is should I go SOHC pistons or DOHC? :12dunno:12dunno:12dunno

 

sohc pistons bumps your compression, it would be alright in the DD but not the KAT

 

That I know, do you think I want my engine to detonate...

This is what I'm looking at with my KA for my DD, while I buold my OTHER engine to a KA-T.

92 240sx hatch
+ 4-2-1 Header
+ Shop made exhaust
+ SOHC pistons
+ Exhaust cam on intake side (Thinking about it.)
- EGR/Emissions
- SCV/Secondary butterflies.

 

I wouldnt do the pistons without a tune...

 

could just bump the fuel pressure, make sure to run primo all the time and retard the timing slightly if your still getting knock.

 

eh, I'd still be more comfortable with a tune.