Mopar 318 5.2l rebuild/upgrade

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TomB

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Hey Guys,

I am planning to rebuild my 318 5.2l V8 mainly stock but with few upgrades. I have Bosch 24lb blue top orange tip injectors also Milodon valves 2.02/1.6 (in know not recommended that big intake but this is what I have).

I am all about low and mid range torque, it would be for a 2500 camper conversion. I probably will gain with a new cam (thinking the shortest duration not sure about the lift but 2.02 intake big enough I guess) also new pistons for the best compression.

Rest, I would like to keep it as it is. Any suggestion? Any help would be approached.

Questions:
Would 24lb injectors with 2.02 intake valves be okay with stock lift? Or better with 21lb injector with 1.92 intake valves and high cam.

New cam and shortest duration, what would be the absolute shortest duration ( I want to separate as much as i can intake and exhaust openings) do I need any lift with 2.02 ?

I want a torque monster what will last, not a screaming high rpm racer.


As I said it's a '00 Dodge 2500 camper (means, I can be anywhere) I also looking a decent guy who would do the job on the budget. It's a slow project I have at least 2-3 month maybe more
 
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I gather you're aiming for fuel mileage.......
At the expense of everything else,
including passing and hill-climbing.
Separating the intake and exhaust events to such a radical degree, may get you mpg on hard level and flat ground, under steady state cruising, from point to point, but this does not take into account the real world terrain and driving circumstances.
IMO, you'll be hard pressed to improve on the 5.2s design for your application.
But if you were willing to upgrade to a 5.9, well then, that could be modded to better suit your application.
Oh, no,:( it too is already set up just right for your application. But the good news is the 360Magnum was born with mega torque.
About all you can do with the 5.9 is to de-cam it to a 5.2 cam, but the compression ratio would also have to come down.IMO hardly worth the expense.
What I mean by that is the pay-back period in fuel savings would be measured in years.
 
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AJ/FormS said:
Hang on man, you're off the rails already.
What's that camper weigh?
What transmission ?
and what gears?
and what year Magnum?
And why did you not start with a 360?
Click to expand...

I am willing to learn educate me

- 6400lbs/7700lbs
- 3spd with overdrive with granny 1st and 2nd A500 or 46RE (none of the shops able to tell)
-3.92 rear end with 16R75 (actually I have 80 on the back)
Vehicle year is 2000, 5.2L, 318CID, SMPI V8, with 225hp 295 ft.lbs what the boos says.

I know 360, it may comes into play if parts I have are junk and I need to replace them. I want to spend reasonably. Economy and torque I need.

I am even thinking tranny swap to manual just read Dakota's or 80s rwd Supra would fit, maybe I could live with the hp/torque i have as stock then.
 
AJ/FormS said:
I gather you're aiming for fuel mileage.......
At the expense of everything else,
including passing and hill-climbing.
Separating the intake and exhaust events to such a radical degree, may get you mpg on hard level and flat ground, under steady state cruising, from point to point, but this does not take into account the real world terrain and driving circumstances.
IMO, you'll be hard pressed to improve on the 5.2s design for your application.
But if you were willing to upgrade to a 5.9, well then, that could be modded to better suit your application.
Oh, no,:( it too is already set up just right for your application. But the good news is the 360Magnum was born with mega torque.
About all you can do with the 5.9 is to de-cam it to a 5.2 cam, but the compression ratio would also have to come down.IMO hardly worth the expense.
What I mean by that is the pay-back period in fuel savings would be measured in years.
Click to expand...

Engine swap another idea, then I always end up wondering about modding the hell out of it and put a Mercedes 3l turbo diesel with manual box.

Do I look like I know what I want? :)
 
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Here are some preliminary numbers, all cams installed at split overlap
1) First the factory 5.2,
Static compression ratio of 9.2:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is 161.70 PSI.
V/P (Volume to Pressure Index) is 133 .
Notice the cylinder pressure is already at the max for pumpgas, and the VP index is pretty good. You're not gonna improve much on this for your application

2) Next the factory 5.9
Static compression ratio of 9.2:1.
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 7.80:1 .
Your dynamic cranking pressure is 154.70 PSI.
V/P (Volume to Pressure Index) is 139.
Again pressure is pushing the limit, and VP is getting up there.

3) Next; the 5.9 with a 5.2 cam
Static compression ratio of 9:1.
Effective stroke is 3.13 inches.
Your dynamic compression ratio is 7.93:1 .
Your dynamic cranking pressure is 158.06 PSI.
V/P (Volume to Pressure Index) is 148
Notice I dropped the Scr, again still pushing the limit, and the VP is now a nice big fat number.

4) Next,stroker
the 5.2 with a 4" arm, and the 5.9Magnum cam
Static compression ratio of 9.4:1.
Effective stroke is 3.35 inches.
Your dynamic compression ratio is 8.04:1 .
Your dynamic cranking pressure is 160.92 PSI.
V/P (Volume to Pressure Index) is 158 ..
I had to up the compression a tad. Notice the VP has climbed to 158/133=plus 18.8%. This is a huge boost in low-rpm performance compared to the 5.2. This is a similar boost to swapping the rear gears from 3.92 to 4.66
Read about VP here..... V/P Index Calculation

5) Here's another;
the 5.9 with a 5.2 cam and with aluminum heads.
Static compression ratio of 10.6:1.
Effective stroke is 2.97 inches.
Your dynamic compression ratio is 8.96:1 .
Your dynamic cranking pressure is 185.09 PSI.
V/P (Volume to Pressure Index) is 166
Check out that VP! this is now 166/133 plus 24.8%!!
Say goodbye to the 3.92s and hello to 3.23s. Now you could be cruising at 65=1530 with still guessing 100 inch tires. That would make a huge boost in mpgs.But I know what you're thinking; how about those heads on my 5.2.Right?
Okay here it is
6) Static compression ratio of 10.6:1.
Effective stroke is 2.74 inches.
Your dynamic compression ratio is 8.93:1 .
Your dynamic cranking pressure is 184.29 PSI.
V/P (Volume to Pressure Index) is 146 ..
At a VP of 146, this is now very similar to the 5.9 with the 5.2 cam. But notice I pumped the Scr up to get 185ish psi. In my engine this pressure is happy with 87E10. So to run these aluminum heads, in your combo, the reason is soz you can pump up the pressure, and not for power, cuz with the 5.2 cam, the absolute power will not be that much better. More power will come from the increased pressure .


The thing about the stroker is that it makes so much power beginning at such a low rpm, that you will be able to run the beast with the throttle valves barely open. And that is where the fuel economy will come from.
But with a stroker and a 5.9cam, you could take some rear gear out of it, and run at a slower rpm down the hiway, and that will theoretically increase your economy even more.
This is usually a slippery slope tho with a smaller engine, as sooner or later,the engine starts to make so little power, that the throttle valves end up quite far open, and economy takes a dive. Theoretically it should be hard for the stroker to get into that, unless you go crazy about reducing the Rs.
__________________________________________________________

But I gotta tell you, if you are getting a confirmed mileage in the 17 to 19 zone, it's hard to imagine any other combo improving enough to warrant spending this much cash on it....unless you are traveling huge amounts of miles per year.
Here is a quick calculation
Suppose you were able to increase your fuel economy to 22mpgs, from 18., and
suppose you traveled 12000 all-hiway miles per year. At 18mpg, this would require 667 gallons, and at 22, just 545, for a savings of 122 gallons.
What's that come to in dollars? Well at 3.15 per gallon this is a savings of 384.30
If you spend $ 3843.00 on engine upgrades that guarantee the 4mpg better economy........it will take 10 years to break even, assuming no change in the cost of the fuel. But if your economy only goes up 2mpg.. then it will take 20 years to break even.
In either case, it is doubtful that you would still be driving it in 5 years, so you would NEVER break even.
 
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Comments in the quote
TomB said:
I am willing to learn educate me
- 6400lbs/7700lbs Not gvws, what does it actually scale at ready to go camping
- 3spd with overdrive with granny 1st and 2nd A500 or 46RE (none of the shops able to tell) Hang on , if it's an automatic, it's an A518 or whatever the modern designation is, and there is no granny in there; the ratios are
2.45-1.45-1.00-69od
-3.92 rear end with 16R75 (actually I have 80 on the back), so what's the roll-out on these bad boys?, the circumference.
Vehicle year is 2000, 5.2L, 318CID, SMPI V8, with 225hp 295 ft.lbs what the boos says.
I know 360, it may comes into play if parts I have are junk and I need to replace them. I want to spend reasonably. Economy and torque I need. Well IMO, forget the 5.2
I am even thinking tranny swap to manual just read Dakota's or 80s rwd Supra would fit, maybe I could live with the hp/torque i have as stock then.
Forget that Supra trans, I doubt it will make 100 miles in your application. Even turbo'd Supra torque, is not Magnum towing a puller-sled torque
Click to expand...

Lets say you get that camper up to 7200 pounds. That's about double what that poor little 5.2 was ever designed for.
And lets say those tires roll out at 100inches.
Now then, your starter gear will be 2.45 x 3.91 x12/15.9=7.23, corrected to a 24 inch tire (12" radius). Compare that to the typical performance set-up, namely 2.45x3.55x12/13.5=7.73
Now think about that; 7.73 for 3600pounds; versus your 7.23 for 7200 pounds.
Let me make it a little easier to understand; suppose the 5.2 manages 130ftlbs at stall.
In the 3600 pound car this would be 3600/(7.73 x 130)=3.58# per ftlb
In your truck, this would be 7200/(7.23x130)=7.66#per ftlb
Now 3.58/7.66= about 1/2, or in other words your truck will be laboring to accelerate at a rate of about 1/2 that of the gutless more-door Swinger.
In other words, you're gonna need double the engine to keep up with that Dart, or double the TM (Torque Multiplication), or some combination of the two, just to keep up.
Now let's look at cruising,in that .69OD. With 100" tires your rpm at 65 will be 1850 in lock-up...........if it will stay in lock-up,......... which I doubt. So lets assume it's gonna be in od/non loc-up. You can expect the Rs to climb 200 for the lock-up, and another 150 in the fluid coupling due to the load the TC is seeing across it, and so my math says....2200rpm@65, (about what the TC stall might be),............if the 5.2 has the power at 2200, at a reasonably small throttle opening, to push that camper-beast thru the wind..........which I also doubt. So it's gonna be sucking gas pretty bad.
But along comes TomB, and wants to detune his 5.2...........with predictable results.

Ok hang on, since the Rs are gonna be up around 2200 anyway in OD/non-loc-up, we might as well up gear it, and try for loc-up again.
So, I suggest 4.56s for what I'm assuming are 31.8" tires.(100inches). So now the new rpm in loc-up will be 2160@65 I still doubt the 5.2 will pull that on anything but deep mains,same as before; but the new starter gear is 8.94, corrected to 24" tires.So that's a reasonable improvement there.
So since AJ thinks the 5.2 can't handle this load even with the 4.56s,we might as well put in that stock 5.9, with the 5.2 cam, that has a VP of plus 11%, (148/133=plus 11%). So now this might translate to 150ftlbs available at 2160, and now it might stay in loc-up. And the long-stroke 5.9 will push that brute of a camper, thru the wind, hopefully at a lot smaller throttle opening.
And that's where the fuel savings will come from.

Yeah I know, long story again.
But as always, you gotta look at the combo.

So I made some dirty-rotten assumptions so your results may vary.
I assumed your tires were 100"/31.8 tall
I assumed you had an A518 trans
I assumed you were right, that there were 3.92s out back

And I made some guesses;
about the factory Scrs and cams found in the Magnums
And the power they can deliver at 2000/2200 rpm
And I guessed your camper was like a slide-in, in that it was a super tall gas-sucking pig of a thing;otherwise you might not be so concerned about fuel-mileage.......lol

So, your results may vary
 
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AJ/FormS said:
Here are some preliminary numbers, all cams installed at split overlap
First the factory 5.2,
Static compression ratio of 9.2:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is 161.70 PSI.
V/P (Volume to Pressure Index) is 133 .
Notice the cylinder pressure is already at the max for pumpgas, and the VP index is pretty good. You're not gonna improve much on this for your application

Next the factory 5.9
Static compression ratio of 9.2:1.
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 7.80:1 .
Your dynamic cranking pressure is 154.70 PSI.
V/P (Volume to Pressure Index) is 139.
Again pressure is pushing the limit, and VP is getting up there.

Next; the 5.9 with a 5.2 cam
Static compression ratio of 9:1.
Effective stroke is 3.13 inches.
Your dynamic compression ratio is 7.93:1 .
Your dynamic cranking pressure is 158.06 PSI.
V/P (Volume to Pressure Index) is 148
Notice I dropped the Scr, again still pushing the limit, and the VP is now a nice big fat number.
Click to expand...
So you saying 5.9l with 5.2l cam brings the best torque? Can we tell ft.lb?
 
AJ/FormS said:
Comments in the quote


Lets say you get that camper up to 7200 pounds. That's about double what that poor little 5.2 was ever designed for.
And lets say those tires roll out at 100inches.
Now then, your starter gear will be 2.45 x 3.91 x12/15=7.66, corrected to a 24 inch tire (12" radius). Compare that to the typical performance set-up, namely 2.45x3.55x12/13.5=7.73
Now think about that; 7.73 for 3600pounds; versus your 7.66 for 7200 pounds.
Let me make it a little easier to understand; suppose the 5.2 manages 130ftlbs at stall.
In the 3600 pound car this would be 3600/(7.73 x 130)=3.58# per ftlb
In your truck, this would be 7200/(7.66x130)=7.23#per ftlb
Now 3.58/7.23= about 1/2, or in other words your truck will be laboring to accelerate at a rate of about 1/2 that of the gutless more-door Swinger.
In other words, you're gonna need double the engine to keep up with that Dart, or double the TM (Torque Multiplication), or some combination of the two, just to keep up.
Now let's look at cruising,in that .69OD. With 100" tires your rpm at 65 will be 1850 in lock-up...........if it will stay in lock-up, which I doubt. So lets assume it's gonna be in od/no loc-up. Youn can expect the Rs to climb 200 for the lock-up, and another 150 in the fluid coupling due to the load the TC is seeing across it, and so my math [email protected] the 5.2 has the power at 2200 to push that camper-beast thru the wind..........which I also doubt. But along comes TomB, and wants to detune his 5.2...........with predictable results.

Ok hang on
Click to expand...

- Veh. loaded weight is 6400lb (that's ready to go camping right?)
- It is granny 1st and 2nd, I am sure! Getting around 17-19mpg at 55mph, to scared to check in the city.

It's build in Canada company called Roadtrek. I am having trouble getting the right parts thanks for them, not straight out from factory 2500 ram van. ie: upper and lower ball joins are cross weight not that straight forward.

What I know about tranny that it has electronic spedo in the connects into the differential.
 
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I know of no automatic for a 2000Ram that has granny gears, nor is it ever called a 3speed plus overdrive. If you have an A500, a 904based maincase then you might have ratios of 2.74-1.54-1.00. These gears are slightly wider apart than the A518, but there is no way you could call the Granny gears. The splits are .56-.65-.69od ....... compared to .59-.69-.69od in the A518, so as you can see, no granny in there.

Ok so now it's a van.
Does it have the big pop-up on top?
And 17 to 19 @55...@6400#...............that's actually pretty good.
With 100" tires that would be 1570 in loc-up. That thing got a tach?
Are those tires the ones specified for the EFI-programmer.
 
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AJ/FormS said:
I know of no automatic for a 2000Ram that has granny gears, nor is it ever called a 3speed plus overdrive. If you have an A500, a 904based maincase then you might have ratios of 2.74-1.54-1.00. These gears are slightly wider apart than the A518, but there is no way you could call the Granny gears. The splits are .56-.65-.69od ....... compared to .59-.69-.69od in the A518, so as you can see, no granny in there.
Click to expand...

Then it's not A500.

I know after 2nd drops rpm way back to 3rd (huge gap) and same to OD. I am locked in to OD at 40 already, I guess previously someone changed shifting points, still it feels like low gear in 1st and 2nd... revs like hell.
 
TomB said:
Then it's not A500.

I know after 2nd drops rpm way back to 3rd (huge gap) and same to OD. I am locked in to OD at 40 already, I guess previously someone changed shifting points, still it feels like low gear in 1st and 2nd... revs like hell.
Click to expand...
Im betting you are hearing the fan, not the rpms.its likely geared for the potential weight and the (lack of) displacement of the engine. You would likely be further ahead to find a 5.9 magnum to pop in there. Mileage and power gain would be easier to attain.
 
No, it's way off I know that. When I said it shifts to overdrive at 40mph according to speedo it's 32ish. (Checked with GPS)
 
Tooljunkie said:
Im betting you are hearing the fan, not the rpms.its likely geared for the potential weight and the (lack of) displacement of the engine. You would likely be further ahead to find a 5.9 magnum to pop in there. Mileage and power gain would be easier to attain.
Click to expand...


I have heard mounting, manifold, sensors are interchangable, Can I strip down my 5.2l and what usable just bolts back on the 5.9l?


Thanks everyone for all the info, again I appreciate it, keep them coming!
 
Theres a balance issue,you will need the 5.9 flex plate with a weight and the balancer to go with it.
 
You say you have a 5.2L and "I want a torque monster what will last, not a screaming high rpm racer."

Well, your best (only?) option then is installing a Scat 4.00" cast crank in it (~$370-400). I'd avoid the Eagle cast crank due to reported breakage issues. The 4" crank and boring it +0.030" will give you a 390ci (~6.4L) engine. Bigger than a 5.9/360 and only slightly smaller than a 408 (360 based) stroker. Another option, just get the entire stroker kit for for around $1,300...

Scat Rotating Assembly Kits - CHRYSLER 340 - 372, 416 SMALL BLOCK STROKER KITS - IBEAM RODS

If you go this route, then the planned 2.02 intake valves won't kill your low end, assuming you keep the cam reasonable/small. Don't want to stroke it...then leave it pretty well stock or do a 5.9 swap.
 
AJ/FormS said:
Here are some preliminary numbers, all cams installed at split overlap
First the factory 5.2,
Static compression ratio of 9.2:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is 161.70 PSI.
V/P (Volume to Pressure Index) is 133 .
Notice the cylinder pressure is already at the max for pumpgas, and the VP index is pretty good. You're not gonna improve much on this for your application

Next the factory 5.9
Static compression ratio of 9.2:1.
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 7.80:1 .
Your dynamic cranking pressure is 154.70 PSI.
V/P (Volume to Pressure Index) is 139.
Again pressure is pushing the limit, and VP is getting up there.

Next; the 5.9 with a 5.2 cam
Static compression ratio of 9:1.
Effective stroke is 3.13 inches.
Your dynamic compression ratio is 7.93:1 .
Your dynamic cranking pressure is 158.06 PSI.
V/P (Volume to Pressure Index) is 148
Notice I dropped the Scr, again still pushing the limit, and the VP is now a nice big fat number.
Click to expand...


Just curious why is there a difference between the examples of the two 5.9 in the effective stroke one you have at 3.2 and the other you have it 3.13?
 
1966DDart said:
you go t planned 2.02 intake valves won't kill your low end
Click to expand...

Is that true that low (or short better word?) duration and low lift can compensate with 2.02 intake?

I am trying to understands the basics, basically better compression 9.5:1 or 10:1 i need to reduce the combustion chamber, (318 headers cast #302, and well selected pistons) for longer time (late intake/exhaust valves opening, early closing) those two article I posted earlier from hotrod really giving me the confidence it can be done, I like the 400ft.lb torque on those setups at mid rpm.

I just need to match the airflow what the 24lb injectors need with the 2.02 duration and lift.
 
Jadaharabi said:
Just curious why is there a difference between the examples of the two 5.9 in the effective stroke one you have at 3.2 and the other you have it 3.13?
Click to expand...
Cam ICA timing is the only thing that can change that.
The first example is with the factory 360 2bbl cam, and the second is with the teener cam.
but 66Dart has a great idea with the stroker crank. I'm gonna back and add that.
OK done and I added some other tidbits.
 
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TomB said:
Is that true that low (or short better word?) duration and low lift can compensate with 2.02 intake?

I am trying to understands the basics, basically better compression 9.5:1 or 10:1 i need to reduce the combustion chamber, (318 headers cast #302, and well selected pistons) for longer time (late intake/exhaust valves opening, early closing) those two article I posted earlier from hotrod really giving me the confidence it can be done, I like the 400ft.lb torque on those setups at mid rpm.
I just need to match the airflow what the 24lb injectors need with the 2.02 duration and lift.
Click to expand...


N No No.
You cannot arbitrarily go bumping compression up, or messing with a proven pkg like a Magnum, for your application. You have to stay within the limits of the available octane rating of the fuel in your neighborhood.
Go back to post #6 and check out how the two magnums have pressure just under/around 160psi. This is considered very close to the limits of pumpgas. If you increase the pressure just a few psi beyond what the gas will support, then the engine will begin to hammer itself to death. Notice I kept the pressure to 160ish on the other two combos, as well.
Next is the valve sizing
Your engine will be operating at very low rpms. A big intake valve will do nothing for it . Zero. The Magnums are already at 1.92, and are more than adequate for your application. Putting the 2.02s in there will be a complete waste of money.As will be changing the injectors.
The biggest problem is always getting air into the engine. This is why we put racing heads and racing cams and racing valves into racing engines. All in an effort to get more oxygen into and thru the engine. Putting the gas in is easy.
But putting air in at 2000/2200 is easy!, you just step on it a little harder. Until it's wide open, then it's done. If you need more power at say 55mph, than the stock Magnum puts out, then you have about 5 choices
1) supercharging
2) a bigger engine
3) Run the Magnum at a higher rpm
4) put the chassis on a diet
5) Aluminum heads and more pressure
For you;2 and 3 are counter productive, on account of they are not likely to gain fuel economy. 4 is out, cuz yer going camping, and 1 and 5 are out cuz that would blow yer budget to smithereens..

Now , there is one exception; You could increase the compression ratio for part throttle operation, if you promised never to press the pedal so hard as to put the engine into detonation.
But we know how that goes..... so instead we just put a really small throttle valve on it, that the engine just cannot detonate no matter what.
But what if the van comes to a hill? And you run out of power half way up? This is about the most dangerous situation that anyone could ever find themselves in, even if you are all alone on that hill. No, that's a really bad idea.
A better idea is timing control. but when the timing is retarded, the engine loses power more rapidly than if the compression was just lower to start with. So this idea is less bad than the earlier example, but it won't solve your issues. And that brings us to water injection. This would probably solve your high-compression pinging.........as long as you keep adequate anti-detonant in the tank.
So that brings us to #5.
With aluminum heads you can increase the pressure a lot,LOT. Like close to 200psi. This works great on a lo-rpm engine, increasing the power from right off idle and on up to shift rpm. If you engineer it right, all this pressure at low rpm can make GREAT fuel economy. But it's pricey. And again, the pay-back period might be measured in decades.
 
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TomB said:
So you saying 5.9l with 5.2l cam brings the best torque? Can we tell ft.lb?
Click to expand...
For you, the 5.2 cam in the 5.9 engine should produce bring the torque band down to a lower rpm. I hesitate to say the "best" torque, but low rpm torque is what you need, to operate at low-rpm; imagine that.The 5.2 cam is very good at making low-rpm torque, and the 5.9 is also very good at that. If you marry the 5.9 to the 5.2 cam, then it stands to reason that such a combo would be superior.And the increase in VP proves it. If you then reduce the operating rpm by less rear gear, then you are practically guaranteed better fuel economy. I'll go work out one more combe, the 5.9 with the 5.2 cam and aluminum heads, I mean just for the fun of it. Post #6
 
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