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400 hp Street 5.2 Magnum Build List

54K views 46 replies 8 participants last post by  siramiksprayz 
#1 ·
Hey guys I need some help! I'm wanting to build the 5.2 in my 1996 dakota to about 400 hp to the rear wheels. I'm looking for some suggestions on a parts list like cam,lifters,rods,pistons,ignition,etc. Keep in mind that this is gonna be a daily driver and farm/work Truck too.I also need it to still get acceptable gas mileage since it's a daily driver.Also, is there anyway I can keep the stock heads instead of spending $2,000 on just heads. I also have a minimal budget. How much would it cost to make 350-400 hp to the rear wheels?Thanks!
 
#2 ·
400hp is almost double what that engine was originally rated for. Can it be done? Yes, Can you keep your heads? Yes. What parts do you need? Well thats hard to say, it will depend on your budget. If you know how to do the work yourself, you can pick up a copy of "How to Rebuild the Small-Block Mopar" from Amazon or your local book store. The author details exactly the parts you need and the work you have to do to get power out of a Mopar engine. If you not doing the work, interview your local speed mechanics, and make sure they are familiar with building Mopar engines, and get an estimate for the build.

Ed
 
#3 ·
Thanks for the reply Ed and yes I will be doing all the work myself except the machine shop work. I'm thinking about Harland sharp roller rockers and what size comp cam should I get? I want something that is fine for daily driver and idle capabilities but not too mild. I want something where you can tell it's cammed but not a rough idle.would I need to do anything to the bottom end?
 
#6 · (Edited)
Will you need to anything to the bottom end? Well it depends on your build. Are you building a stroker? There are tons of ways to build an engine and there no one size fits all approach to this.

Reality is, no one is going to recommend a particular cam because no one knows how you plan to build your engine. Every cam is different, for a reason. Never select a cam based on a sales brochure The best suggestion is to contact different cam builders and tell them what you have in mind and shop around for the best deal. Be prepared to answer a bunch of questions too, concerning your build. If you're in the dark as to what you'll need to reach your HP goal, either buy the book or find a local mechanic who specializes in performance engine builds, particularly those who can build a Mopar.

Keep in mind as well, that your engine may not get better fuel economy. 400hp out of a small displacement engine is a lot to ask for. You're either building for power or economy. Its really tough to get both. Another thing, while that lopey cam sound is bad ass, it isn't going to be good for saving gas.

Ed
 
#11 ·
You're going to have to wait on 400HP then.

Power isn't cheap. The stroker is just about the cheapest way to up the horsepower on an older, tired motor, since you really need to rebuild the lower end ANYWAY.

But, hey, if you don't care about blowing it up, you can always go for a 200 shot or so of nitrous. It'll be fun, as long as it lasts. Might even get three or four pulls on it ...

RwP
 
#10 ·
Thats really not a bad price for a stroker which will certainly get a 318 to 400HP or more. Understand that you're not going to get to 400HP with a 318 on a cam alone. You also should consider that if the engine has some miles on it, that you'll be replacing parts, and your build will probably cost a couple of grand (And that could be just for the basic rebuild) If your budget is tight, you may want to think about an engine swap to something either already putting out 400HP or something that won't take much money or effort to get to 400HP, such as a big block swap.
Your only other option if funds are limited is to reach for a more attainable goal, like building for 300HP instead of 400HP. But it's also going to depend on the condition of your engine.

Ed
 
#12 · (Edited)
Has anyone read the op's original post? It said he wanted 400 hp at the rear wheels which means his little 318 would need to make 485 hp if it's an automatic. To answer the op with all of the criteria you mention in two words....no way.

You would need a good 10 grand to just get you started. Then you'd have to spring for some type of power adder such as a sc or nitrous. You would make next to no vacuum with the cam needed to support 485 hp n/a. It would have to become strictly a race truck otherwise. Personally, you are barking up an entirely wrong tree. Don't believe magazine articles in the least.
If you want a nice drivable truck, put in a cam with short duration of less than 210 @.50, a set of shorty headers, stronger springs to support a cam of no more than 480 lift. Put a 3 angle valve job on your current heads leaving the keggar intake with a mopar performance pcm a cold air intake with a Fastman 50 mm TB and then just enjoy your added gas mileage and livable street/farm truck.
 
#13 ·
Has anyone read the op's original post?
Uh yeah. I was the first to respond, come to think of it….

It said he wanted 400 hp at the rear wheels which means his little 318 would need to make 485 hp if it's an automatic. To answer the op with all of the criteria you mention in two words....no way.

You would need a good 10 grand to just get you started. Then you'd have to spring for some type of power adder such as a sc or nitrous. You would make next to no vacuum with the cam needed to support 485 hp n/a. It would have to become strictly a race truck otherwise. Personally, you are barking up an entirely wrong tree. Don't believe magazine articles in the least.
If you want a nice drivable truck, put in a cam with short duration of less than 210 @.50, a set of shorty headers, stronger springs to support a cam of no more than 480 lift. Put a 3 angle valve job on your current heads leaving the keggar intake with a mopar performance pcm a cold air intake with a Fastman 50 mm TB and then just enjoy your added gas mileage and livable street/farm truck.
I will agree with you that this kind of build won't be cheap. I disagree in your two word response of "No way"

I believe it's totally possible to build a 318 to make 400 "RWHP", and that such a build could be driven on a daily basis, and get "acceptable" fuel economy (If he can resist the urge to nail the throttle to the floor)

IMO the best way to get there is by building a stroker motor. Anotherwords, via increased displacement. Currently several "kits" are available to stroke a 318 out to 370, 390, 396 or 402 cu.in.

Once the displacement is there (and he's in big block territory) it's well within the possibility to get within the 400 RWHP ballpark….

Here is a "stroker" 360 available thru Mopar with 408 cubic inches of displacement:
http://www.moparproshop.com/inc/sdetail/6202/12364
You'll note that the engine is rated at 480hp. Thats within the ball park of what he would need. The 318 shares the same block as the 360 and if he goes with the max displacement of 402cu.in, which is available for that engine, he will only be short 6 cubic inches, so thats going to be within ball park too. Or he can mix and match other speed parts, such as using a hotter cam or different intake, so that even if he used a stroker kit that had one of the smaller displacements, he can still be within ball park of his desired goal. If he tries to build a 318 for 400RWHP without increasing displacement, it will be much more difficult and probably be less "user friendly".

His best options to build a 318 for 400RWHP is either;

1) Massive engine mods, porting polishing, big intake, possible multiple carbs, etc

2) Forced induction…Supercharging or Turbo

3) Injectables, thats Nitrous, or Water/Meth

4) Converting to Nitromethane

5) Stroker kit Or,

6) A combination of all of the above

None of the options above will be cheap even if he takes on all of the work himself….Except maybe Nitrous. In fact he could leave the engine alone and just hit it with about a 200hp shot of nitrous and reach his 400rwhp goal….But then again, after a couple of shots, it's still gonna end up being an expensive endeavor.

The only way to get there is;

1) Save money, until you have enough

2) Reduce your HP goal to say 300rwhp

3) Use another engine, such as a 440, or for those who like to live on the edge, a Viper V10

4) A combo of all of the above……or,

5) Forget it and live with what you got

Ed
 
#14 · (Edited)
I have to disagree entirely. I am not sure you are reading his full criteria. He wants a truck with added gas mileage for not so much money and be used as a street/farm truck. To all of THIS COMBINATION, I still contend-"no way". A 200 shot of nitrous on a stock motor might hasten the end of that motor especially w/o the proper essentials for running nitrous. Will the op be cognizant of fuel pressures or timing take out or atmospheric conditions or burn gauging or intake temps? It is the cheapest route to hp but a 100-150 shot seems more reasonable for a stock motor and even with a 200 shot, this will never produce 400 rwhp. Do not forget that whatever he produces at the crank, he will lose 20% of that in an auto so in actuality, he's lucky if he is currently making 160 rwhp.Will he spring for the additional money toward the transmission to support that kind of power?
He is asking way too much as he does not need hp as much as he needs torque. Sure you can build a 500 hp 318 but do you want this as a street/farm truck? A 500 hp 318 and the word "cheap" is an oxymoron. I think it a totally unreasonable quest. The only part of your post I concur with for HIS reality is lowering his expectations but even to 300 rwhp is not enough.
If he does the things I suggested, I think he will be more than happy and actually meet his goals.
 
#21 · (Edited)
I have to disagree entirely.
You are free to do so, I'm just giving my perspective based on my perception and experiences

I am not sure you are reading his full criteria. He wants a truck with added gas mileage for not so much money and be used as a street/farm truck.
I read the OP's full criteria and no where does he say "added" gas mileage. His words were "reasonable" gas mileage. Considering that "reasonable" isn't exactly defined, we can't simply assume "reasonable" equals "added". It's easy to assume that he wants "added" economy, considering we would all like "added" fuel economy, but I think the OP maybe smart enough to figure out that added economy probably isn't possible if he wants 400hp. My guess is he probably doesn't want to get pummeled at the pumps either. It's a logical view to have if he understands that more HP equals more fuel is gonna be used. Now having said this, if his build is done just right, I don't believe he's going to get "terrible" fuel economy, but in my opinion, to stay within the ball park of what his fuel economy is now, he needs to increase the displacement and that means Stroker

Next in his original post, the OP says he wants to do this for "not a lot of money". Now, considering that he lists off a few parts, he never really specifies what he is willing to spend. So we don't really know what "not a lot of money" means to him. For all we know, he may have tons of money and is a tight wad, or he's just another working class Joe with 2.5 kids a wife, a dog and a ton of bills. All we do know about the guy's finances is what he tells us, and later in the thread, he says the stroker isn't within his budget. But's thats usually the case with anything we may want. Sometimes the things we want the most aren't within the budget and thats why I gave a few alternatives.

To all of THIS COMBINATION, I still contend-"no way".
For the OP, maybe, maybe not. It all depends on how much the Op has to spend, and what he's willing to compromise on.

Now, let me tell you that it's quite possible, because I've done it. I got a 5.9 in my Dakota now, that pushes close to 400hp and will see 20 mpg. From the cost perspective, I spent less on my engine then if I were to use the original 318. All I did was swap engines, I added bigger injectors and a big turbo. Thats it. My engine didn't cost much, and heres the best part, the engine wasn't rebuilt. It's got about 160K original miles on it. Total cost for the HP upgrades was under a grand. So how did I do it?? I stuck a Cummins under the hood. Yes my story is a bit deceiving because I spend a small fortune on numerous other parts like the drivetrain and transmission, but the point is anything is possible if you keep things in perspective including your personal finances.

A 200 shot of nitrous on a stock motor might hasten the end of that motor especially w/o the proper essentials for running nitrous. Will the op be cognizant of fuel pressures or timing take out or atmospheric conditions or burn gauging or intake temps?
I'm not sure you understand the meaning of sarcasm. A 200hp shot of nitrous will blow the pistons out the oil pan the first time you hit the button. The bottom line here, nothing is cheap and theres no quick way to make big horsepower (unless you live in a manson and fly your personal jet to polo games)

Sure you can build a 500 hp 318 but do you want this as a street/farm truck? A 500 hp 318 and the word "cheap" is an oxymoron. I think it a totally unreasonable quest. The only part of your post I concur with for HIS reality is lowering his expectations but even to 300 rwhp is not enough.
But he wasn't asking for 500HP, thats a huge exaggeration, he was asking for 400HP, thats a huge difference! If he were asking for 500HP, I'd say thats a lot to ask from a 318. 400HP is about the max I would even consider, and HP gets exponentially more expensive, the higher you go.…

A typical stock 318 is good for about 230HP (And yes a 200HP shot of nitrous would get him in the ballpark…..once!) So he needs to get at least an additional 200HP out of his engine. I sarcastically stated Nitrous will do it…..but don't expect the engine to survive. I pointed out the different ways to get there, and the way I'd personally get there is go Stroker for the larger displacement which is actually a less stressful way to get big power out of a smaller engine. However not knowing how much the OP has to spend means he may have no choice but to lower his HP goal. 300HP is far more reasonable and maybe closer to his affordability. Remember, the 318 is rated for 230HP(net) All the OP needs to do is make a 70HP increase.

He is asking way too much as he does not need hp as much as he needs torque.
As for torque…Yes, he needs as much torque as he can get, but there is an inseparable relationship between Torque and HP and can be clearly seen by the formula;
TQ X RPM / 5252 = HP

Now our OP wants to get 400HP out of his engine. So based on the formula, there are an infinite number of combinations of TQ & RPM to reach 400HP. He can use a 4 cylinder, a big V8, or even a diesel, so long as the combination of torque and rpm equals out to be 400hp. (Of course if you were using a 4 cylinder, it would need to produce a lot of torque, otherwise it would have to rev at insane rpms to be at 400hp) Now our OP can try to build the engine for torque but the only proven ways to build an engine for torque is thru greater displacement and/or improved volumetric efficiency (Thats forced induction) and yet there will still be limits. But if you're building a gas engine for torque, you're really building for HP anyway because of an interesting mathematical phenomenon found in the formula. An engine turning at 5252 rpms is making the same horsepower as it is torque. For example, if an engine was making 300hp at 5252 rpm, it would also be making 300 lb-ft of torque at 5252 rpm. That would also mean that all engines that run below 5252 RPMs tends to make more torque than horsepower and all engines that run above 5252 RPMs tends to make more horsepower than torque. This is why a diesel seem to produce more torque and why gas engines seem to produce more horsepower. Most diesels aren't even capable of rpms above 5000 rpms while gas engines tend to come alive over 5000 rpms. Because of this curiosity in the formula, if you compared a 400hp gas engine to a 400hp diesel, the gas engine running above 5252 rpm would be making less than 400 lb-ft of torque, while a diesel running below 5252 rpm would be making more than 400 lb-ft of torque. So to get back to the question, with a gas engine, building for torque "is basically" building for HP there is no way to isolate each and there no way of getting around it.

Ed
 
#16 ·
Underdog, you should be getting better mileage with the 408. Something is off in you build. If your cam is too big or has too much duration for the much beloved rummpity sound everyone desires, that can hurt mileage.
Did you get a tune for your motor after the build?
 
#20 · (Edited)
UD. Oh...It's carbed. That explains the gas mileage. I never got better than 10-11 mpg with the 750. I like your cam choice. Most guys chomp at the bit to get over .525 lift in their builds. Your truck runs quite strong. The new body styles on the Dakotas (97-2003) are something like 300 lbs heavier. Put your engine in one of those and you'd get12.5's.

I'm not certain ppl are understanding your complaint of low gas mileage as a problem. I know some guys with EFI on their 408 builds get 12-15 mpg if they stay out of it.I also know that when guys are running a steeper gear say like 3.92's or 4.11's, their mileage actually improves as a result of the engine being happier in a more efficient power band.
Your cam would have had to be a bit lower in duration to get better mileage. I can only hope the fun factor of your truck makes up for the mileage.
 
#22 · (Edited)
Boy, you and I are diametrically opposed. Believe me, I do not need a lecture on hp-torque but if it was a benefit for the op (I wonder where he went btw) then I could see your dissertation.
I do not feel you can include your 360 build as we have no way of knowing what the op is capable mechanically speaking. Right now he seems more of a "bolt-on" type of guy or else he would not have asked the question in the first place if he had true experience.

I also think you keep forgetting one very important factor. It is not 400 hp he wants, he wants 400 rwhp. This means his truck would most certainly have to approach almost 500 hp (or closer to 485 hp) @ the crank. C'mon now, a 318 to produce that kind of power would be an astronomical chore along with an expense.

In the realms of reality and not argumentative semantics as you seem to relish in, I think he would be perfectly content with a mild build starting with just the cam of around 206-210 duration and .475 -.480 lift. What you know as well as I do, to achieve higher hp you are moving the torque band higher and higher. A cam with 246* of duration @ 50 will put out more hp at the expense of bottom end torque. As you may think 70-80 hp more is not so much to achieve, I'd say yes for a 360 and not so much for a 318. With the about $3500 of expenditure with my recommendation, you'd be quite lucky to achieve 300 hp. With a set of EQ heads, you'd get closer. Perhaps an intake swap, TB and maybe going with a 3.92 or 4.10 rear and with the exception of 400 rwhp, all of his other goals would be achieved.

My word, it's his farm truck for heaven sakes. He could be a kid who just got his license and the boy up the street just ass whipped him with his 85 Camaro. Do you really see him in the outer world of us engine nut addictive hp sickos?
 
#23 ·
Boy, you and I are diametrically opposed. Believe me, I do not need a lecture on hp-torque but if it was a benefit for the op (I wonder where he went btw) then I could see your dissertation.
Yeah (and because there are others who are following, if not the OP)

I do not feel you can include your 360 build as we have no way of knowing what the op is capable mechanically speaking.
If we didn't include my "360" (or more appropriately, my "5.9") build, I couldn't make my "anything is possible" point (and you would have caught the part where I said my "5.9" was a Cummins ;)

Right now he seems more of a "bolt-on" type of guy or else he would not have asked the question in the first place if he had true experience.
I'd agree with that. Understand that in my point, there is more than one way to skin a cat…. or build an engine for a particular power level. Part of the reason I brought up the torque/horsepower relationship is that it shows that there are an infinite number of combinations between TQ & RPM to reach a particular goal. And knowing that, it means there are an almost infinite number of ways or combinations to build an engine. Some more or less expensive than others

I also think you keep forgetting one very important factor. It is not 400 hp he wants, he wants 400 rwhp. This means his truck would most certainly have to approach almost 500 hp (or closer to 485 hp) @ the crank. C'mon now, a 318 to produce that kind of power would be an astronomical chore along with an expense.
If he ain't got the money or skills, it will be an astronomical chore for him to get 300rwhp or even 250rwhp. At this point it's all just speculation of what the OP could actually afford. If the OP was an average Joe, then I would agree whole heartedly that it's too much to ask (and I did say that he might want to consider a lower power level or use a different engine)

In the realms of reality and not argumentative semantics as you seem to relish in,
But I love a good argument…..

I think he would be perfectly content with a mild build starting with just the cam of around 206-210 duration and .475 -.480 lift. Perhaps an intake swap and maybe going with a 3.92 or 4.10 rear and with the exception of 400 rwhp, all of his other goals would be achieved.
I certainly couldn't tell you what the Op would be content with. All I know is he asked a question and we don't know why he picked a number like 400rwhp? I could speculate and say, maybe he's trying to outdo a buddy or rival, maybe he likes how the number "400" sounds when he says it?

Is it "achievable" to build a 400rwhp 318? Again, I can't tell you what would be "achievable", because it isn't my money. For me, I felt it was "achievable" to drop a Cummins into my Dakota, but there is going to be someone else who doesn't think it is"achievable" or reasonable. The OP came back later and said it wasn't affordable for him….Ok, thats fine, we tried to help and gave him our opinions and thats all we can really do.

For me to agree with the "No way" aspect of your point, I'd have to know more about the OP…….From an "anything goes" point of view. 400rwhp out of a 318? Sure, No problem!

Ed
 
#34 · (Edited)
Wouldn't doubt it. These heads crack between the valve seats and some are hairline. They are meaningless until they move through a water jacket. It is said that Chrysler used thinner castings to save money from 1995 on for their magnum motors.
if you were to get a set of Engine Quest heads, these would eliminate the "crack issue".
Even a mildly massaged EQ head will produce in the 251 cfm range as opposed to the 190 somethings of the magum heads.

The only thing "mild" about your cam is it's lift. The duration is just fine. I think for your engine, the most lift I'd go is about .550 keeping the same duration. You'd pull harder right from the line compared to your present cam.
You can also put in 1.7 rockers if you do not already have them and boost your present lift by about 30 points.
 
#38 · (Edited)
They are iron. A bare set would run about $650. A medium worked set including valves, springs, keepers etc. would run about $12 - $1500. A fully ported set would be in the $22-$2400 range.
They do make them for the LA bolt pattern.


Low 12's is more than acceptable in my opinion. A few changes and you're in the 11's. It does (or it should) have to stop somewhere however.
These heads should do 11's for ya.
 
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