Hi guys, been lurking around for a little while. I have an '84 Shelby Charger that I'm dropping a '96 Avenger 2.0 DOHC into, actually already have it set in, working on finishing up motor mounts and figuring out electronics and exhaust.
Now, I'm leaving it stock for now, till I get this thing running and driving and work out all the bugs. However, after that, I'm gonna build it up, going all-motor. Looking for advice and ideas on cams, internals, valvetrain etc. I'm thinking at least 10.5:1 compression and hoping to spin it to at least 8k or more. Loss of low end power is acceptable as long as it's making big power up top. Car weight will hopefully be around 1800-2000 lbs w/ me in it.
I'm on the Neon forum too, since the bottom end is the same, but I'm not sure how similar the heads are, w/ the Avenger being "backwards" from the Neons. Do the cams interchange?
Thanks for any help, anybody have an idea what hp one of these engines can make NA?
the cams for a neon WILL NOT work. You must find cams for the 420A Eclipse. I suggest going with a turbo if you really want power. Or bottle feed it but IMHO turbo is the way to go. People have spent tons of money going the N/A route and not getting very far as far as HP (I am probably wrong and will be notified shortly if I am).
My advice, build up the bottom end like DT and I did, and then turbo it. If you are dead set on N/A let me get ahold of Zilla and find out what he did and what he is pushing as far as HP. I probably still have his parts list somewhere as I helped him get a lot of stuff.
Sounds good, I'm still kinda up in the air about it actually. The general consensus everywhere seems to be turbo it, but I'd like to do something different. I already have turbo cars ('87 Shelby GLHS, '87 Shelby Z Daytona, '87 RX-7 Turbo II), so I want to do an NA car. I like road racing/mountain runs more than dragging also, so it's gonna be geared more towards that. I'd like to build a lightweight responsive car to that purpose. Basically I want a strong mid to top-end engine, like I say low-end can be sacrificed a bit since the car will only weigh around 2000 lbs w/ me in it.
If your looking for better acceleration why are you willing to sacrifice low end? If you're doing mountain runs with a lot of turns you want a better low end power to get up and go. If you do a turbo go with a small quick spooling turbo that will get you out of corners quick.
If you do forced induction run 8.8:1 compression. If you're going to stay N/A the highest compression they make (without paying ridiculous amounts for custom) is 12:1 they're hard to find though. The 10.5:1 is common and cheaper.
And if you want to do something different than everyone else drop a 420a into a '84 Shelby Charger..... You've completed the different task, so turbo is good to go.
Also don't do N2O, just too many things to go wrong for a short lived thrill. (What was that you told me Nykon 75 dollars to press a button??)
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Mod List. Um WAY too many to fit on here. But the engine can handle about 800HP
NOS....not something i would do or recommend....Turbo is much better. dont have one of these engines, but I wouldnt keep it N/A with what ur already doing to it. if the motor can handle it..do it to it.
If your looking for better acceleration why are you willing to sacrifice low end? If you're doing mountain runs with a lot of turns you want a better low end power to get up and go. If you do a turbo go with a small quick spooling turbo that will get you out of corners quick.
If you do forced induction run 8.8:1 compression. If you're going to stay N/A the highest compression they make (without paying ridiculous amounts for custom) is 12:1 they're hard to find though. The 10.5:1 is common and cheaper.
And if you want to do something different than everyone else drop a 420a into a '84 Shelby Charger..... You've completed the different task, so turbo is good to go.
Also don't do N2O, just too many things to go wrong for a short lived thrill. (What was that you told me Nykon 75 dollars to press a button??)
Well, turbo may come later, we'll see how it does all-motor. I can lose a little low end, because it's gonna be light, and it'll have a good deep gear if it needs it. I've got it bolted to a stock A-525 trans, as long as my starter works right (as I think it will), then I can run stock 2.2/2.5 trannies. And I have a 525 sitting in the shop w/ a 3.85 gear What's the powerband/max rpm limit on the Avenger heads? 8500? 9k?
without updating the springs / retainers.. you'll start to float the valves at about 7500rpm..
trying to go with a naturally aspirated rpm / highhp motor is.. well.. folly.
everything about this engine has been designed for low~mid rpm torque.. (low being about 2K rpm.. mid being about 4.5K)
unless your tossing the whole intake tract and custom welding your own, reworking the ports and engineering an exhaust from the port back.. your tossing $ into a slow hole..
if it's gonna be light.. work on the mid rpms.. thats where you'll get the biggest gains.. being a 2.2/2.5 guy.. be aware that the 2L is really an evolution of that motor.. and like the 2.2/2.5.. isn't really something designed to rev.. it IS however.. like the 2.2/2.5 a torquey little bish that can pull itself out of a hole (or corner as it were) and well.. that's where your gains are best realized..
the engine will rev faster from 3K~5K than it will from 4K ~7K
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2001 Sebring Coupe - V6 5sp 1995 Sebring Coupe - I4 5sp Political correctness advocates the proposition that it is entirely possible to pick up a turd by the clean end.
without updating the springs / retainers.. you'll start to float the valves at about 7500rpm..
trying to go with a naturally aspirated rpm / highhp motor is.. well.. folly.
everything about this engine has been designed for low~mid rpm torque.. (low being about 2K rpm.. mid being about 4.5K)
unless your tossing the whole intake tract and custom welding your own, reworking the ports and engineering an exhaust from the port back.. your tossing $ into a slow hole..
if it's gonna be light.. work on the mid rpms.. thats where you'll get the biggest gains.. being a 2.2/2.5 guy.. be aware that the 2L is really an evolution of that motor.. and like the 2.2/2.5.. isn't really something designed to rev.. it IS however.. like the 2.2/2.5 a torquey little bish that can pull itself out of a hole (or corner as it were) and well.. that's where your gains are best realized..
the engine will rev faster from 3K~5K than it will from 4K ~7K
Okay, looks like I'm kinda off track on my thinking for this build. Building for hi-rev hp is a no-no then, will make it a dog everywhere else right? So, I think what I need is to just see what you guys think would be the best combo for this criteria:
Lightweight car, 1800-2k lbs w/ me in it Road race/mountain road suspension/chassis set-up Best combo of power and responsiveness
I'm totally open right now, my original ideas are apparently useless and I'm a noob to these engines. Should I be building for torque rather than hp? As you say it is an evolution of the 2.2, and that's what you do w/ them basically, typically a 2.2 makes a crapload more torque then hp.
build up the midrange.. everyone always tries to build these engines for high rpm power.. and i haven't seen one come close to breaking 180hp.. even revving the snot out of them and dropping stupid amounts of money into them..
but.. they'll pull a damn near perfect flat torque line from 2K to 6K rpm..
one of the reasons these motors respond so well to boost...
put in some 10:1 pistons.. don't put in a 60mm throttle body.. stick with a 55.. work on air charge velocity.. not overall volume.. I suggest some reading on fluid dynamics and pressure vs flow anaylsis.. oh and throw out anything that mentions hemholtz resonance theories... resonance is important.. but not THAT important that it should be the primary design concern.. be more aware of using high and low pressure areas to reduce reversion in the intake and exhaust track, than "tuning for good sound".. your not building a pipe organ.
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2001 Sebring Coupe - V6 5sp 1995 Sebring Coupe - I4 5sp Political correctness advocates the proposition that it is entirely possible to pick up a turd by the clean end.
How much power do these engines have stock? Has to be around 150 crank hp right? Basically the same as a Neon R/T engine, except w/ a backwards head, maybe different cam grinds. Seems to be pretty tough to make 200hp all-motor though. I'm hoping the light weight will make up for a lot of it though. What the factory torque rating?
140hp 130lb-ft of torque.. at the wheels on a mostly stock engine.. i saw 120hp and 110lb-ft
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2001 Sebring Coupe - V6 5sp 1995 Sebring Coupe - I4 5sp Political correctness advocates the proposition that it is entirely possible to pick up a turd by the clean end.
So it takes some pretty good head porting and high compression to make the big numbers? Sorry if I sound repetitive, I just want to get the build right in my head before I start. What about valves? Do bigger valves make that much difference? And how does the stock intake fare? Any better options on it?
I'm still set on an all-motor build right now, but only to a certain point. Basically, if it's gets to the point to where an extra 10-15hp is gonna cost me $1000 or better, then I'll turbo it. BTW I do all my own work, other than machine work, so I won't have any labor to pay in this build, except for buying myself Mt Dew for the shop fridge
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You've completed the different task, so turbo is good to go. 
