ok guys here it is proof
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IveBeenBad
- Posts: 1138
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- Car: 1990 Nissan 240SX Fastback STOCK BIOTCH
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deviousKA
- Posts: 1355
- Joined: Tue Aug 12, 2003 5:04 pm
- Car: 90 240sx NA /72 Datsun 510 NA /86 corolla GTS NA
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goomba240 wrote:Does anyone know what Month the 89's switched to 8.6.1 compression? Im afraid to try and start my car now lol.
http://wac.addr.com/auto/240sx/240sx.html
easiest way to tell is by the temp sensor in the airbox. Sometimes these have been removed/fallen off etc.... like when people put aftermarket intakes on so make sure.
Edit: btw, disregard this statement "Since displacement, bore and stroke are all unchanged, the compression ratio change was done either with a bored out cylinder head or with a thicker head gasket. No mention is made of either in the Service Bulletin". The compression ratio change is due to the pistons.
is it possible to find these pistons in a overbore size? sounds like most people pull the high comp slugs out of old motors and dont do machine work. i'm getting a motor to rebuild and want to have all the machine work done if its neccessary. and if needs to be slightly overbored then i'll need to get the right piston size.
so i guess my question is can you still get the high comp pistons in a overbore size??
so i guess my question is can you still get the high comp pistons in a overbore size??
cory2081 wrote:Yeah, the pistons would have a deeper dish for the lower compression engines. If you are afraid to start it, check the valve clearance. It takes some time to do it, but, saves the trouble of bent valves if there isn't enough clearance.
I got the pistons out of a November 89 car. No one knows the month(if there is one) that it changed?? I guess im gonna have to check for clearence problems now...
I just purchased a ka24de head to try and do some work to it. my neighbor has a machine shop with a ka24e motor with a fresh rebuilt collecting dust. i believe he said it was bored .030 over and smaller pistons were put on to keep compression down. any idea if this will help with preventing the valves from coming in contact with the pistons?
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TrunkMonkey
- Posts: 3190
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- Car: 2000 Lincoln Navigator
That answers my question.I read the thread and I just want to get this straight, by swapping the ka24e bottom end for the de bottom end all I am essentially doing is changing the pistons? So if I have a de already I would probably be better off just changing the pistons out. Is there any advantage efficiency wise of the e bottom end over the de bottom end?
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glacier985
- Posts: 390
- Joined: Fri Jul 18, 2003 4:30 pm
- Car: 72 Datsun 240Z
90 Nissan 240SX
11 Subaru WRX Wagon
16 Nissan Rogue - Location: Central Ohio
smug510 wrote:wow i had no idea this thread would get so big , i am pretty happy with the swap , really in the begining i just wanted to do it b/c nobody has , i would say it pulls more consistantlly than the turbo , i have lots of tourqe low end and then it wants to still go but the cams limit it , but all in all if you like to fabricate and you want to do something different than this is a cool swap but if your not the most mechaniclly inclined than the piston swap would probably be best , i can definitly say that i am the first to do this , but i am giving up on it , the high comp datsun 510 is up for sale , i am going to pick up a 97 240 se and do a swap , i am definitly going with a rb26dett , the datsuns fast but not nearly fast enough , so have fun with the head idea
troy a.k.a. smug
Since your the only person to complete this, could you maybe do a how to or take some more pictures before you sell the car? I am going to attempt this swap in the next month and I want as much info before I start.
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hotboy_intrigue
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OK this is the best NA thread I have seen yet for my 1990 - but for a nissan noob could someone summarize the things that need to be addressed to put a DOHC on a SOHC block.
To keep it simple assume I were to take 1990 SOHC short block and put a 1991 DOHC head on using the 1990 distributor.
Lastly does anyone know of the valve to piston clearances? Could one of the mild to moderate aftermarket DOHC cams be used?
Are there any reflash technologies available to the end user for these ECUs? Or if not what are the preferred stand alones? I don't want to get into piggy-backing to correct fueling and I want timing control and data logging.
To keep it simple assume I were to take 1990 SOHC short block and put a 1991 DOHC head on using the 1990 distributor.
- Of course the manifolds and injectors would be with the DOHC heads - will the 1990 ECU, sensors and wiring run this motor?
- Would I need the 1991 ECU, sensors and wiring?
- If I do this there will be no AC on the car anyway - but do I need the 1991 power steering?
- What exactly is the timing chain cover solution?
Lastly does anyone know of the valve to piston clearances? Could one of the mild to moderate aftermarket DOHC cams be used?
Are there any reflash technologies available to the end user for these ECUs? Or if not what are the preferred stand alones? I don't want to get into piggy-backing to correct fueling and I want timing control and data logging.
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better_than_sx
- Posts: 98
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- Car: 1989 240sx
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turboICE wrote:Also it is not entirely clear to me where the compression change on the SOHC came from. Was it a change in anything at all on the short block? A change in the piston? Or was it a change in the combustion chamber of the head? I mean if the SOHC compression change had anything to do with the SOHC head shouldn't a DOHC head still bring the same resulting compression of this thread?
Apparantly, it seems that the dish piston volume from the early 89 was less than that of the late 89-90, thus raising the compression ratio. It seems like the combustion chamber volume was the same throughout 89-90.
For all of your other questions, I'm trying to do research and get answers for as well. But it seems that you're supposed to use the dohc stuff... I still don't understand why though. Anyone knowledgeable want to chat on AIM with me? - crzycav24 ...I'd like to ask some questions.
i asked this sometime back and never had an answer. seeing as how it was a design change, replacements in the .5 over would be non-existant. there probably is some aftermarket stuff. but this is supposed to be a low budget affair. so if you wanted to do this you either have to dish out the bux for pistons, or skip out on having the block bored.
anyone??
anyone??
if you buy high comp pistons you have to pull the motor and take apart the whole bottom end to put it in. if you swap on the sohc head, you just unbolt the head, get a new head gasket, do some mods and bolt it on. plus its cheaper: people are GIVING AWAY sohc heads. I dont see many people giving away high comp pistons.
nah dont do that if u put the sohc head on ur block ya your going to get higher compression but at the same time your cam timing is going to be crap becuz your going to be usin the sohc cam and your intake/exhaust tunning? The cams arent seperate and u cant tune each cam seperately on advance and retard all u can do is advance intake and exhaust as the same degrees which will b shetty cause they are on the same cam.