SOHC pistons in DOHC
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Dattebayo
- Posts: 33297
- Joined: Sun Aug 25, 2002 10:04 am
- Car: 2004 Frontier Desert Runner
- Location: NE DC
SOHC pistons in DOHC
when trying to achive 10.1 compression, i understand you need the sohc pistons. I have seen at nismoparts that there are 89.5mm and 90mm pistons available. Using the 90mm would have more compression, but what compression would you get for each? (what a cool cheaper mod)
Not sure if you can just throw 90mm ones in there, but if you can, I bet it will increase the compression to 10.5:1 Do a search, and I started a thread a while ago talking about putting SOHC pistons in a DOHC car...i guess the 8.5:1 SOHC pistons make the compression ratio 11.1:1...pretty high. Just search "pistons"
yup
Yup, just search pistons, and on the third page theres a thread asking about installing KA24E pistons for increased compression...lengthy thread too. 8.6:1 pistons in a KA24DE yields 11.1:1, 9.1:1 yields 11.6:1 compression, which is the highest you should go on pump 93 gas
Ceptos wrote:how much would something like this cost? it cant be all that cheap, can it, dont you have to take out the engine to replace the pistons? or at least be able to come at the pistons from above and below to replace them. unless you are doing it yourself, would this be exspensive?
Expensive is a relative term. Since you're replacing pistons, you'd want to at least go through and check the crank and assembly, maybe replace the rod and main cap bearings. Depending on tolerances, maybe a light bore to get the clearance right in the cylinders. Other things will come in to play to push the price up, head gasket, etc, so it could get expensive, but much less than a full rebuild, or mild headwork. You would also want to a little tuning, maybe with an ECU upgrade, to compensate for the higher compression.
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Dattebayo
- Posts: 33297
- Joined: Sun Aug 25, 2002 10:04 am
- Car: 2004 Frontier Desert Runner
- Location: NE DC
quote from markEmark, "i guess the 8.5:1 SOHC pistons make the compression ratio 11.1:1"
okay explain it to me. first of all, the compression is listed as 8.6:1, prolly just an oversite on your behalf. but what really gets me is that the new pistons (89.5 AND 90MM) are listed on the site as 9.1:1 for sohc. is the cylinder head just bigger on a sohc or is there another reason for this weird difference between sohc and dohc?
okay explain it to me. first of all, the compression is listed as 8.6:1, prolly just an oversite on your behalf. but what really gets me is that the new pistons (89.5 AND 90MM) are listed on the site as 9.1:1 for sohc. is the cylinder head just bigger on a sohc or is there another reason for this weird difference between sohc and dohc?
Haha, I'm definitely not the person to explain to you WHY the SOHC pistons increase the compression, like I said, search for that old post, they might say something about it in there. The SOHC pistons were different than the DOHC pistons, so when you put the in a DOHC engine, it increases the compression....8.6 gives 11.1, 9.1 gives 11.6....Or, you could put a thinner head gasket in and increase the compression that way....You found the pistons to be only $38 a piece? Where?!?
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Dattebayo
- Posts: 33297
- Joined: Sun Aug 25, 2002 10:04 am
- Car: 2004 Frontier Desert Runner
- Location: NE DC
they are at http://www.nismoparts.com They have everything you'd ever need for your SOHC and a few DOHC oe parts. when you go to the site DONT CLICK ON NISSAN. just click "accessories" on the top right. just trust me, youll get lost if you do.
im a little afraid to use the 9.1:1 pistons offered on this site in my engine 'cause i got aftermarket cams...
im a little afraid to use the 9.1:1 pistons offered on this site in my engine 'cause i got aftermarket cams...
If you dont want the 11.6 compression, then go with the 8.6:1 SOHC pistons to get 11.1...I don't see why aftermarket cams would be a problem with higher compression pistons, rather,i think they'd work beautifuly with them...just ask Don at PDM what he thinks about high compression pistons + his PDM cams...He knows plenty about stuff like that...
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