2.0 DOHC build idea.

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fargo59
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2.0 DOHC build idea.

Post by fargo59 » Sat Mar 15, 2014 4:11 pm

so i seem to have come to a point where my neon's short block is making enough piston noise to warrant my concern. so me being me, i think of ways i can make something better. lol...

here's the plan so far. ive found, and am in the process of buying an NGC 2.0 R/T block, bedplate and crankshaft. the deal was really nice so it can sit in my shed until i have everything.

-2.0 R/T block
-2001 PT DOHC head, i have one used, i had planned to use on my mom's pt.
-off the shelf 2.0 DOHC piston and rod assemblies. compression should be 9.6:1
-exhaust manifold from a PT cruiser, should bolt to my current high flow cat's stock flange.
-intake manifold has me torn right now, the easy option is an SRT4 intake. realizing this isnt the best option but is a direct bolt on for me. finding one for a decent price makes the challenge.

-timing covers will come from a 1gn neon DOHC. 96-99 use the same part numbers as the 2.0 PT's.

same with Timing belt. standard 1GN DOHC part

stock fuel injectors should be plenty for the application. the 2.0 DOHC used in export PT cruisers used the same injectors. fuel delivery should remain the same.

camshafts, i'd like to use some 2.0 cams, but since i have the 2.4 head, i already have the cams to match. something to consider.

engine management: i have an idea i want to try. i'd like to try running the export PT cruiser calibration in a stock controller. im not sure if anyone has tried this, but it sort of seemed like an idea worth trying at least for a bit.



eventually i may go boost with the setup, in which case i'll need to replace the rods, pistons, and exhaust manifold. (along with controller) but that can come later. i'd like to get this up and running this summer since this is my commuter car and honestly, i like the idea of something a bit different for an engine.

im sure i am missing many of the little details. accessories, etc. the car is an 03, manual SXT, so i felt the DOHC might add a bit of fun. i dont particularly need fast though. i dont have the budget for 2 fast cars. lol.

any thoughts?

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Post by fargo59 » Sat Mar 15, 2014 4:54 pm

hmm, second thought, 1gn DOHC rod and piston assemblies arent available any more. i guess i could opt for sealed power pistons.

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Post by occasional demons » Sun Mar 16, 2014 12:49 pm

The 2.4 cams are really low lift. You will probably loose some power over a regular 2.0 DOHC/SOHC. I would at the minimum go for some 2.0 cams. I just seen some on ebay for $50ish, IIRC. If you have $ to spend, maybe a mild set of cranes, or BC cams.

If you don't have stock rods, try for some good used Magnum rods as your first choice. Regular ones will do just fine if you cannot find a set from an R/T or ACR.

The '95 to '00 IM is supposed to fit to the 2001 up head with some redrilling. I haven't seen it personally tho.
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Post by fargo59 » Sun Mar 16, 2014 1:21 pm

i had heard that swapping the starter motor was required though. perhaps im wrong.

the block i purchased was an R/T block that someone bought for their own car, but took all of the magnum related parts to drop in their SBEC block. i dont have rods at this time. i'll keep an eye on the forums, since OEM's are sold as rod/piston assemblies.

I'm considering buying aftermarket rods and pistons to set compression where i want (9.5-9.6:1). eventually i'd like to add some boost, so pistons would be handy. either way i will be filing the ring gaps to handle a tad (2 bar max) of boost.

i will definitely add the 2.0 cams to the shopping list.

things ive discovered along the way:

1gn DOHC's have a compression ratio of 9.6:1.
2.0 DOHC PT's have a compression ratio of 9.4:1

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Post by occasional demons » Sun Mar 16, 2014 5:05 pm

Well if you are boosting, I don't know the cams would make a huge impact, but for N/A, you probably wouldn't be real happy with the 2.4 cams in a 2.0. All the 2.4 cams are the same, regardless if they are in a turbo car or not.

The 2.0 cams would still give a slight edge for boost tho.
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Post by INVUJerry » Sun Mar 16, 2014 5:14 pm

fargo59 wrote:i had heard that swapping the starter motor was required though. perhaps im wrong.

the block i purchased was an R/T block that someone bought for their own car, but took all of the magnum related parts to drop in their SBEC block. i dont have rods at this time. i'll keep an eye on the forums, since OEM's are sold as rod/piston assemblies.

I'm considering buying aftermarket rods and pistons to set compression where i want (9.5-9.6:1). eventually i'd like to add some boost, so pistons would be handy. either way i will be filing the ring gaps to handle a tad (2 bar max) of boost.

i will definitely add the 2.0 cams to the shopping list.

things ive discovered along the way:

1gn DOHC's have a compression ratio of 9.6:1.
2.0 DOHC PT's have a compression ratio of 9.4:1
North America never got 2.0 PT's.

A DOHC block under a sohc head makes 10.3:1 compression.

To do a dohc swap you will need a 1gn style starter, not a huge deal. You could get a no-90 lower from modern performance which helps with NA and boost performance.

A 10:1 or even 10.5:1 compression ratio wouldn't be too bad under boost, just have to be careful with your timing advance. It will also help driveability with the car out of boost, or before you boost it.
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Post by fargo59 » Sun Mar 16, 2014 5:30 pm

right, boost will be down the road. i just want to set up the short block once though. balancing rotating assemblies (if using aftermarket parts) is something i only plan to do once.

i need a drivable car while i accumulate boost related parts. lol

the 2.0 cams will be just fine for me, once i find them. i saw some on ebay today. i may order them and ship to my friend's place in pennsylvania.

when i said 2.0 PT, i meant export. I'm going by dealerconnect service information. while im not a guru on the PL/PT platform, having a decade as a chrysler tech comes in handy :)

i'll be using an NGC SOHC block under a PT DOHC head, so the pistons need to be swapped to up the compression to my target. 9.5ish would give it a decent N/A feel, while it can still take 12 PSI comfortably with proper tuning. when it does finally go boost, it will be tuned with an SRT4 controller and a few friends i have made over the years (same ones who tune my charger)

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Post by INVUJerry » Sun Mar 16, 2014 5:36 pm

Off the shelf pistons aren't really available in stock compression ratio. Most are going to be 8.8 or 10.5:1, although there are head shims out there, but they mess with the cam timing a bit. To get stock 2.0 cams just grab some from a junkyard neon. I bet (the user) Canada has a spare set sitting around somewhere.
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Post by fargo59 » Sun Mar 16, 2014 7:45 pm

thats what im noticing. sealed power sells pistons which seem to fit the compression, but are hypereutectic. granted, if the rings are set right that wont be a problem.

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Post by occasional demons » Sun Mar 16, 2014 7:47 pm

INVUJerry wrote: A DOHC block under a sohc head makes 10.3:1 compression.
Since she is doing the opposite, and hasn't acquired pistons yet, SOHC pistons would be ~9.5:1 for '95 to '02 SOHC pistons, and ~9.0:1 for '03 to '05 pistons with the DOHC head.
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Post by fargo59 » Sun Mar 16, 2014 9:19 pm

so here's my dillema. the Sealed Power pistons will get me to my ideal compression, but are press fit wrist pins. not too much of a big deal. basically stock replacements.

for rods, i could go OEM replacements, but thats not handy with boost. Eagle makes a nice rod, but they're floating pin style. i suppose those could be converted, just seems a waste. almost better to convert the pistons.

manley rods dont list one way or another.

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Re: 2.0 DOHC build idea.

Post by NickKo » Sun Mar 16, 2014 9:39 pm

"timing covers will come from a 1gn neon DOHC. 96-99 use the same part numbers as the 2.0 PT's."

So, it can be made to look 'factory stock'.... :-k

That is how I would build it, anyways. :D


- Nick
-1998 2-dr SOHC MTX= 57mm TB; Maddog STS
-2000 Ply.LX w/MTX = Maddog STS; CAI; 2.5 exh.; 60mm T/B
-2001 ATX w/Syked PCM + Magnum header
-2001 ACR w/SRT T/B bored out to 55mm

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Post by fargo59 » Sun Mar 16, 2014 10:23 pm

thats how i work, :)
"nice car, have you done anything to it?" is something i get a lot when people look at my charger. lol.

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Post by occasional demons » Mon Mar 17, 2014 7:34 am

To convert the pistons, you would need to have a way to retain the wrist pins. A lock ring groove would need machined into them. probably not going to be much cheaper than off the shelf full floating pistons by the time you are done.

The oem rod ends could be honed out for full floating, but you still have stock rods. Unfortunately with these, it is either all in or all out, as far as pistons to rods.

At least with the 2.4, you can use SRT rods and have full floating aftermarket pistons on them.

The Magnum rods are the same material as the SRT rods, but still not nearly as strong, due to the mass difference.
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Post by fargo59 » Mon Mar 17, 2014 8:22 am

Yeah, I'm fine with buying eagle or Manley rods. Its back to pistons if i cant get those set up for semi floating from the start

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Post by stdlystdmufn » Wed Mar 19, 2014 8:25 pm

put an 01 PT head on my 05 sxt and did not need to replace the starter. (i didn't have the mopar starter on anymore though) also one little thing i ran into that i overlooked reading all the DIYs here and the other org was the fuel line that connects your fuel rail to the chassis hard lines. the DOHC head takes up MUCH more space in the engine compartment and a lot of things need to be re-routed
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Post by fargo59 » Thu Mar 20, 2014 12:34 pm

Good info! I'll be sure to either make my own fuel line or re-route it to work properly.

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Post by occasional demons » Thu Mar 20, 2014 2:49 pm

How different is an SRT line? (As far as location on the firewall?) It would be correct as far as going across the head, at least. But if the firewall location is too different, it may not work with the regular location.
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Post by fargo59 » Thu Mar 20, 2014 5:47 pm

Good point. I'll have to price out the fuel line, and compare some photos while i'm at it

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Post by stdlystdmufn » Thu Mar 20, 2014 9:16 pm

srt fuel line should work just fine but it was much easier to make my own -6 line and i could get any color i wanted instead of the black plastic
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Post by fargo59 » Thu Mar 20, 2014 10:16 pm

actually i kind of want to keep the black plastic. my plan is to look quite stock (just cleaned up)

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Post by stdlystdmufn » Fri Mar 21, 2014 11:47 pm

thats what i wanted too, like a stealthy stock look. so I used black nylon wrapped -6 line.
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in the middle of a DOHC and MTX swap and going with an ASP kit pwered by the S259 batmowheel

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Post by NickKo » Sat Mar 22, 2014 10:58 am

stdlystdmufn wrote: the DOHC head takes up MUCH more space in the engine compartment and a lot of things need to be re-routed
Something else to consider !!
Thanks for mentioning this.


- Nick
-1998 2-dr SOHC MTX= 57mm TB; Maddog STS
-2000 Ply.LX w/MTX = Maddog STS; CAI; 2.5 exh.; 60mm T/B
-2001 ATX w/Syked PCM + Magnum header
-2001 ACR w/SRT T/B bored out to 55mm

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Post by SPL Neon » Sun Mar 23, 2014 8:27 am

I have a set of 2.0 cams in Ontario if you can't find any. Only thing is I'm about 3hrs away from the Falls. While the head is sitting around, you may as well port it. I also have a ported upper DOHC intake manifold but the thermostat housing has been removed so a status/pt/SRT housing would be needed.
1996 SOHC + 66hp Nitrous- 12.81@105mph
08 CSRT-4 Realtune MS1K PCM, RM Drag Springs, MPx MM Inserts, 03 NSRT4 Injectors, LaminX Yellow Fog Film. Daily Driver 32+mpg
2000 LE daily driver - in need of modifications

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Post by fargo59 » Sun Mar 23, 2014 9:46 am

thats really nice of you. im currently waiting on a shipping quote from someone on the other .org, so we'll see. they seem to be taking their time.

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Post by SPL Neon » Sun Mar 23, 2014 2:35 pm

Cool, well if things don't work out; hit me up! :-)
1996 SOHC + 66hp Nitrous- 12.81@105mph
08 CSRT-4 Realtune MS1K PCM, RM Drag Springs, MPx MM Inserts, 03 NSRT4 Injectors, LaminX Yellow Fog Film. Daily Driver 32+mpg
2000 LE daily driver - in need of modifications

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Post by fargo59 » Sun Mar 23, 2014 5:19 pm

oh i just might. but only if you dont have a use for them.

the head will be getting some port work (mostly exhaust side) while it sits, as well as a 3 angle valve job. i'll probably mill a tiny bit off the deck just to clean it up.

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Post by akirony » Sun Nov 16, 2014 9:51 pm

Hey fargo how far have you gotten with this setup or did you end up scrapping the project?
Have car-have car problems. Have srt4-have speed problems
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Post by fargo59 » Sun Nov 16, 2014 11:56 pm

honestly i sort of set it aside for a bit. i have the block, and head, etc. was sourcing other stuff. but between drag racing the charger this fall (so close to 10's!) and coming close to buying a dart instead, i really didnt get anywhere on this.

kind of funny that tonight is the first night ive logged in here in a while.

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Post by NickKo » Tue Nov 18, 2014 7:23 am

fargo59 wrote:honestly i sort of set it aside for a bit. i have the block, and head, etc. was sourcing other stuff. but between drag racing the charger this fall (so close to 10's!) and coming close to buying a dart instead, i really didnt get anywhere on this.

kind of funny that tonight is the first night ive logged in here in a while.
10's in a Charger ?? :shock: It looks like you have accomplished something while you were away !! :D

As for myself - One of my 'project cars' (1998 Neon) sat in the backyard, for 3 (or was that 4?) years, before I finally got around to replacing the engine in the car.
Once I replaced the engine, it became a trouble-free 'daily driver'. It fired up and ran for the first time, in about 4 years !! Like it had never been down. :D


- Nick
-1998 2-dr SOHC MTX= 57mm TB; Maddog STS
-2000 Ply.LX w/MTX = Maddog STS; CAI; 2.5 exh.; 60mm T/B
-2001 ATX w/Syked PCM + Magnum header
-2001 ACR w/SRT T/B bored out to 55mm

Official "I'm Going to Drive My Neon till it Dies" Club #000009

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