question about pistons

robleen69 · 07-24-2008, 06:08 PM

well i bought a shortblock from a 95-99 SOHC neon with stock (flat) pistons and im putting my 95-99 DOHC head on it will the pistons in the short block work or do i need to get DOHC eclipse pistons please let me know i must get this project back on the road

I was just wondering because my buddy told me QUOTE( I know those pistons will NOT work in that motor.. SOHC pistons are machined flat and DOHC are designed dished for a reason, for valve clearance, and for proper compression.. If you run those pistons you are either A) smash the valves B) have extremely high compression and float them..)

murray1 · 07-24-2008, 07:15 PM

The pistons are NOT the same. Neon SOHC engines have different pistons then Neon DOHC engines. I am not sure yet if Neon DOHC pistons are the same as Talon/Eclipse pistons.

I found this topic that has some great information. Link

Interesting

Quote:

You can get creative and swap a SOHC head on a block that has DOHC pistons and it will yield a compression ratio of 10.3:1
(more compression = more power)

Or

You can swap a DOHC head on a block that has SOHC pistons and it will yield a compression ratio of 9.3:1. This setup is an ideal setup for turbo applications. The lower compression will allow you to run a higher PSI of boost, while the individual cams will allow you to custom tune your timing much easier.
(NOTE: when swapping only heads, you also need the appropriate timing belt and components, along with intake and exhaust manifolds, pcm, wiring harness, etc.)

From what this looks like I think you would be able to swap the SOHC block in. I am not 100% sure about this though. I am currently wondering about the opposite(putting a talon/eclipse block in a neon.

Edit: That site has a lot of good info if you search there.

mrmozambique13 · 07-24-2008, 07:41 PM

As stated in the link that you posted, the blocks are the same. The SOHC and the DOHC have diffrent size combustion chambers thus giveing the SOHC a 9.8:1 ratio. So yes the pistons are the same.

murray1 · 07-24-2008, 07:48 PM

Stop posting shit if you don't know what you are talking about. The pistons ARE DIFFERENT. SOHC pistons are flat, DOHC are slightly domed with valve reliefs.

Here is another couple links to help figure this out
Link
Link

From what I am seeing it should work either way(using SOHC or DOHC pistons with a 420a head).

99RedGs · 07-24-2008, 11:16 PM

Im pretty sure they won't work

bullettdsm · 07-25-2008, 05:10 AM

Hmm.......

OK, first off, mrmozambique13 be real careful about misinformation. It can spread like wild fire.

Statement: the SOHC and the DOHC pistons are obviously not the same. Period

Statement: You can safely use the SOHC pistons with the DOHC head. Period.

Statement: if you use SOHC pistons with DOHC head you will lower your compression (to about 9.3 to 1 vs 9.6 to 1 stock). Period.

And yes, Murray, the Neon DOHC pistons and our pistons are the same.

robleen69 you won't really notice any difference in .3 comp as a daily driver. One thing you may have to deal with is the 95 SOHC block has a different breather set-up. It has a breather on the block. You can either block these off with the appropriate size freeze plugs or you can set something up to re-use the block breather. IF you are rebuilding the bottom end you also have different main bearings in there (but I think you are just slapping it on).

MB

robleen69 · 07-25-2008, 01:03 PM

Quote:

Originally Posted by bullettdsm

Statement: You can safely use the SOHC pistons with the DOHC head. Period.

Statement: if you use SOHC pistons with DOHC head you will lower your compression (to about 9.3 to 1 vs 9.6 to 1 stock). Period.

robleen69 you won't really notice any difference in .3 comp as a daily driver. One thing you may have to deal with is the 95 SOHC block has a different breather set-up. It has a breather on the block. You can either block these off with the appropriate size freeze plugs or you can set something up to re-use the block breather. IF you are rebuilding the bottom end you also have different main bearings in there (but I think you are just slapping it on).

MB

it has the same breather set up that my old stock GS block had but it had a SOHC head on it and had SOHC pistonsin it w/less than 10k on them... iknow the pistons arent the same... i just wanted to kno that im not gonna damage my valves by useing those pistons with a DOHC setup... so thank you all who have been trying to help.. HAS anyone here done this swap before .. i put eagle H rods in there with new bearing piston ring ect. just kept the pistons.. as someone else stated before will this be a good setup for a hahn stage 2 or 3 turbo kit

murray1 · 07-25-2008, 07:09 PM

Thanks Bullet, that makes my searching easier now. It also helps me kill 2 birds with one stone(my brother can always use a running car...). He is 18 and already wrote off 3, blown up an engine in another one and needed repairs on yet another car not worth it...

bullettdsm · 07-26-2008, 04:33 AM

Quote:

Originally Posted by murray1

Thanks Bullet, that makes my searching easier now.

No prob Murray, glad it made it a little easier

OP, this set-up has been done many, many times. I personally have not done it, but I have done the SOHC block to the DOHC head, lol. Great that you don't have to alter any breathers.

IMO, the extra comp won't kill you if you go turbo. But you're still not forged pistons so I would be especially careful with the tuning.

MB