Power limitations of the early Magnum

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Baxter61

Baxter61

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Looking at hopping up my truck that is a 92 with a 5.2 magnum. Debating how much I want to try and up this thing and where the giant leaps in money are needed. So curious what are the limitations of the factory keg intake, injectors, and PCM.
 
I've done what you're going to do. If you're looking to do it right, you're going to spend a lot of money. Plan on spending at least 5k just for engine modifications, if you're going to do it right (ex. machining, getting quality parts, etc.). If you REALLY are looking into doing it correctly, plan on spending about 10k. This includes things like a new tranny, new electrical, new rear end, custom driveshaft, all the machine work, custom stuff, etc.

This is just my personal experience, I'm in the midst of wrapping up my build. I trashed the auto tranny in favor of a 3spd, and upgraded my rear end with one from a 2003 dakota that I modified to fit Durango breaks. I also converted it to carb so I had to buy a new intake, all MSD timing/ignition stuff, etc. The list goes on. I'd reccomend straying away from the fuel ignition. It'll cost you more, and you have to futz around with the computer, which won't let the new engine anyway and then just give you problems with everything else.

TL;DR
Scrap the FI, go with carb. If you're only upgrading the engine with nothing else, plan on spending at least 5k if you plan on doing it correctly.
 
xLURKxDOGx said:
Do tell...........:coffee2:
Click to expand...

Do tell WHAT

Guy says he wants more power, nobody knows how much and the next thing ya know we're doin' a 10G build along with trashin' what might be a perfectly good EFI
 
dakotadude, where have you all these years when I was building 400 hp FI engines for $2500-$3000? I want you to buy from me instead so I can double my prices :D

OP, you can get a pretty easy and inexpensive 300-350 out of it. If you want a big bump in power, swap in a 5.9 short block. EQ heads and nice cam, injectors and pcm flash will get you to 350-380 hp. Injectors on late model 5.9 will flow better than 5.2 ones by a few #/hr.

If you want to wake it up with your block, EQ heads, cam and pcm flash will get you 325. The ffactory intake will actually outperform or match most aftermarket ones up to 4000 rpm, how often do you rev past 4500? Hughes/Edel Air Gao FI will cost you $599 and get you more power than keg but only after 4000 rpm. Our ignition upgrade will get you about 500 RPM over stock, maybe more plus better idle and 2-3 MPG over stock. pm or look us up for more info. We have spent last 17 years doing Wrangler magnum swaps so are very familar with heavy vehicles and have custom tailored cams for 4500+ lb vehicles with deep gears and large tires, much different than the car stuff.
 
5.9 as stated is the better choice. They seem to be plentiful, at least around here. 5 Grand should get you 300, 350 HP in your car.
 
Also somewhere floating around the web is a mod for the beer keg for a little more top end
 
The thread is on here, if its an early intake you have to remove the center divider and if you have a later one you dont. Both will need about an inch taken off inner side of runners at angle which will net you about 500-750 higher pull past the 4000 ish point that they start to flatten out. Google magnum intake mod and you will find several threads and vids.
 
is it unreasonable to try and get into the 12's in a 4300 lb shortwide with 4.10 gears on street tires with the keg intake after the mods to the intake and a pcm flash? if I shoot for 14's I want to do it with the 5.2, if I can get into the 12s with the keg intake i'll do it with a 5.9. if I cant get into the 12's with a keg intake I likely wont take it that far.
 
WOW!!! I guess I can NEVER afford to mess with the magnums.... LOL!! 1st, impossible to run them at all with out EQ Heads (a quick grand). 2nd, never mind... LOL...
Maybe when I'm done with the "low dollar 318" build thread, perhaps I'll start a low dollar 318 mag build.... Under 700.00 bucks??? Hmmmm.....
 
Curious... What do you use to flash the computer and where do you get the maps for larger injectors? What size injectors are stock and what sizes can you replace them with? How large of a cam can you run with the stock computer?
 
Good luck, because there is sooo much information scattered all over the place it's ridiculous.

What I can tell you for sure is that you can get assembled EQ Iron Magnum heads for just under a grand and they are a direct swap upgrade over the factory 318 heads by a long way.
1.92 intakes and 1.6? exhaust with 172cc runners and a 62-3 cc closed chambers and flow around 230 un molested.
OOTB they flow better that almost any mild performance oriented replacement OOTB head.
They can come with lift capable springs up to about .600 still about 1k

I'm in the middle of a carbed 5.9 with these heads and a 218/224 cam for 300 hp and it'll be under 2k finished.

You would need to get the plenum repair kit and your computer re flashed if you go over about 200 duration and I read that is somewhere around 400.
I also saw where you can replace the injectors with bigger ones and there were part numbers but I don't remember where or how much because I am going carb and not injection so I didn't pay much attention.

Ask how much to spend on this website and you will get 10k responses, but ask what they would do with their own money and it'll be a lot closer to what told you. :D
 
Baxter61 said:
is it unreasonable to try and get into the 12's in a 4300 lb shortwide with 4.10 gears on street tires with the keg intake after the mods to the intake and a pcm flash? if I shoot for 14's I want to do it with the 5.2, if I can get into the 12s with the keg intake i'll do it with a 5.9. if I cant get into the 12's with a keg intake I likely wont take it that far.
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Might be a bit optimistic on 1/4 times, it is a 4500 lb vehicle. I would check out some of the Dakota boards to get ET's on a truck and what they have done. They are much more FI oriented than around here. I would think that the 5.9 with cam and flash will get you into 14's if done correctly, 12's would require quite a bit of modification and close to 500 hp.

318willrun, not sure if your comment was directed a me but EQ heads are not mandatory, they just make 14's in a 4500 lb truck much more realistic than stock heads. We built lots of nasty magnums prior to EQ heads, EQ's just end up saving tons of time and money, unless you work for $1.75/hr . Everybody is free to build and port magnum factory heads, I just dont recommend it as they tend to crack. If you are on a budget, the factory heads can make some power, if you choose to gamble with your time and $$$. I cant because its customers $$$ not mine.
 
^^^ not you, but to say instantly 5 grand on just motor, and 10 grand to do it right, who can play in our hobby????? Also, I agree the EQ heads are a plus in performance, and they may not crack, and if in the budget a it's money well spent, BUT............. the factory magnum heads are the best small block mopar heads made from the factory, so they will perform. And as far as the cracks, well, it don't seem to bother the running of the car at all. In fact, to know if they are cracked, you got to take them off. Are my heads cracked on my 5.2 Durango at 202,***?? Or on my 5.9 at 229,***???? Most likely, but no one know because it runs fine, doesn't overheat, ..... get what i'm sayin?

P.S. - to the OP, I watched a 92 Dakota 2wd 5.2 with factory 3.90 gears automatic turn 14.60's off of a computer upgrade. No mods to the intake, no EQ heads, no cam change, no headers, no injector change.
 
Myself I couldn't put cracked heads back on an engine I had apart even though most of the time they are probably runnable.
The REAL problem with doing that is if a section of a cracked seat starts wandering around in your cylinder. (and it happens)
It's not just the head metal that cracks, but the seats where the heads did also sometimes.
I have one here right now with 90k on it and cracked head metal and intake valve seats both and I had to completely disassemble them to see it.
I personally couldn't risk a perfectly good 5.9 short block on it.







318willrun said:
^^^ not you, but to say instantly 5 grand on just motor, and 10 grand to do it right, who can play in our hobby????? Also, I agree the EQ heads are a plus in performance, and they may not crack, and if in the budget a it's money well spent, BUT............. the factory magnum heads are the best small block mopar heads made from the factory, so they will perform. And as far as the cracks, well, it don't seem to bother the running of the car at all. In fact, to know if they are cracked, you got to take them off. Are my heads cracked on my 5.2 Durango at 202,***?? Or on my 5.9 at 229,***???? Most likely, but no one know because it runs fine, doesn't overheat, ..... get what i'm sayin?

P.S. - to the OP, I watched a 92 Dakota 2wd 5.2 with factory 3.90 gears automatic turn 14.60's off of a computer upgrade. No mods to the intake, no EQ heads, no cam change, no headers, no injector change.
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not really suggesting putting cracked heads on a motor, just say'n that you can add things to a good running engine.
 
318willrun said:
not really suggesting putting cracked heads on a motor, just say'n that you can add things to a good running engine.
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On that note I was thinking to mention he could just leave the heads alone and pop a better cam in it.
It REALLY wouldn't be a bad idea to put stronger springs on it at the same time since the stock ones will float valves so easy. (and possibly even be weak enough to stick one open)
But that can also be done without removing the heads.

Then he might have 500 or so into it and probably 250-280hp but still have to flash it for the lowered vacuum signal.

About 200 for the springs, retainers and locks.
About 150 or so for a regrind roller
Probably new pushrods for the reground lower base circle cam

With a flash on top of that we're getting close to 800-1000
 
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