Max HP limit for 360 magnum stock bottom end?

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maca

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Hey guys
Anyone know or found the HP limit for a 360 Magnum stock bottom end?
I have pushed the stock magnum cranks, rods and pistons time and time again with no breakage. I dont rev it past 6000rpm but i do push plenty of HP through these stock parts. Anyone know their limits or what they are capable of?
 
You can throw as much power to it as it can make, as long as the mixture is rich and the timing is conservative. I run a 318 mag to an estimated 450 torque from 10lbs of boost. Lots of folks run oem short block on boost with just upgraded crank and rod fasteners.
 
Another thing to consider is the extra life added to a motor with a center weighted crank, which evens out the stress on the main bearings and webs, along with the crank itself. I run one in my 528 drag motor, and though expensive it was worth it. I had cap walk in a megablock, and the center weighted crank eliminated it from the # 2,3,4 mains. Add to that a better main cap and studs and I bet a stock block would tolerate more power than most would think.
 
Excellent question and while I do not have a clear answer for you I can only point to a memeber UOP that runs his into the 11's. It was also in a light car, but, 11's is it is so far as I know.

I guess, unless someone actually dyno'd there stock bottom end Magnum, we won't know for sure BUT a drag strip slip and the cars known weight (exactly if possible) along with there running gear set up should help pave the way to more knowledge and a good idea of the approximate power level of the engine.

Let's here it from the been there and done that crew running and racing Magnums!

Whatcha got? How did you do it? What parts did you use? How fast did you go with what set up with your cars weight?
 
The reason I was asking is because I'm currently running a Turbo and Last time I tuned it everytime I added 1 pounds of boost and pulled out one degree of timing I was gaining 30 to 35 horsepower. It was like a licence to print horsepower.lol
I have been running 430hp at the wheels for 2 or 3 years now in a 3250lbs car.
With the easy horsepower gains on the last tune I ended up stopping it at 620 rear wheel horsepower as the A518 stock transmission started to struggle.
I have read guys have been running 100 horsepower per cylinder but I don't know if that's at the wheels or at the crank. I imagine that's about where I would be 800 at the crank or close to it.
I know once I get used to this power I will probably be looking for more lol but I don't know many people running that sort of power on stock bottom end.
 
Till it splatters itself all over the track.
 
maca said:
The reason I was asking is because I'm currently running a Turbo and Last time I tuned it everytime I added 1 pounds of boost and pulled out one degree of timing I was gaining 30 to 35 horsepower. It was like a licence to print horsepower.lol
I have been running 430hp at the wheels for 2 or 3 years now in a 3250lbs car.
With the easy horsepower gains on the last tune I ended up stopping it at 620 rear wheel horsepower as the A518 stock transmission started to struggle.
I have read guys have been running 100 horsepower per cylinder but I don't know if that's at the wheels or at the crank. I imagine that's about where I would be 800 at the crank or close to it.
I know once I get used to this power I will probably be looking for more lol but I don't know many people running that sort of power on stock bottom end.
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A big problem with one max hp estimated limit for all applications is that turbo horsepower is easiest on the bottom end, followed by belt driven supercharger, then the toughest on the motor is normally aspirated.
Stress levels per Hp vary because power to drive some superchargers is not recorded on a dyno sheet.
 
gregsdart said:
A big problem with one max hp estimated limit for all applications is that turbo horsepower is easiest on the bottom end, followed by belt driven supercharger, then the toughest on the motor is normally aspirated.
Stress levels per Hp vary because power to drive some superchargers is not recorded on a dyno sheet.
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YEH that makes sence. I have noticed that as boost seems to come on a little smother than NA power that my engines and transmissions have survived a ton of punishment
 
Didn't realize you were on boost. For what it's worth, a guy in Denver ran a 318 mag to 16 lbs of boost in a white Dakota breaking 600 torque on a dyno. There is a YouTube video out there and a results thread where lots of folks call him a liar but at the very end (weeks or months after the dyno) I think he ends up bending some rods.

Naturally aspirated I'm sure you can make as much power as atmosphere and displacemtn can shove in.

How long it lasts is a different story.
 
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Thats interesting. Im trying to find out my torque still. I am on 6 psi on low boost 430hp
And 15 psi on 620hp
How do you know when you bend rods?
Engine out of balance or compression changes or it just stops
 
A friend boosted a junkyard 318 to 500+ hp. before it let go,,,,,,,,,, 15 psi IIRC, no intercooler, just a "let's push it till it blows" test on a dyno .
 
maca said:
Hey guys
Anyone know or found the HP limit for a 360 Magnum stock bottom end?
I have pushed the stock magnum cranks, rods and pistons time and time again with no breakage. I dont rev it past 6000rpm but i do push plenty of HP through these stock parts. Anyone know their limits or what they are capable of?
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Maca,

As always what are your expectations with this stock bottom end? Make it through a season, 5 years, a dyno session for bragging rights? What is the limit? Windowing the Block?
Just because a motor will put down numbers at a dyno tune session that does not give Any guarantees. The quality of the tune, the fuel, and assy are critical. Do you have a knock sensor arrangement? Are you spraying water/meth? What compression? Rings gapped correctly? Oiling system up grades? Crankcase venting upgrades? Exhaust Valve upgrades to Inconel? Quality fasteners throughout? Etc, Etc. If most of these are no then you are on borrowed time.

I don't know what is a good number, 400? 450?

Marion
 
I found the thread on the truck forums if you wanted to take a look. He ran 91 octane w/ intercooler and auxiliary fuel injectors. On a bone stock bottom end he says. Lots of miles on it, so I'm sure that helped with clearance and tolerances but didn't help with its lifetime stress. Turned it up to 17psi (corrected to sea level). Bent some rods, cracked some skirts, and busted some rings. I remember using a lot of this guys info and mistakes to tailor my turbo mag, I went with E85 to help cool things down, especially the piston tops. Either way, he made a stock 318 mag live for quite some time in a heavy (4500+ lb.) truck. I'd say 600 is the "limit" but that depends on how well it's built. Some may last longer, some shorter.

There is another guy who commented on there who made high 500's with a supercharger and stock bottom

318 single turbo made 560 wheel!!! - Dakota Durango Forum
 
Thanks guys
I realise there are lots of things that can kill the bottom end but assuming all these things are fine I was wondering if there is a weak point that will let go but it seems I might be the one to find out.lol
I am running E85 with an intercooler and controlling my afrs with my laptop so its not lean. It has edelbrock heads with good valves and studs etc but the bottom end is bone stock. I have been running a supercharger with 8 psi at max rpm for a few years but now its turbo and making a ton more power. All the boost is in by 3000rpm. I cruise it on its low boost setting most of the time but high boost at the track. Will be interesting to see how it goes.
 
8psi? I don't see many issues. Especially with E85, it cools things down nicely. Your top end combo sounds better than most. A lot of guys take stock everything and boost it higher and higher, adding more and more heat to make power. You have alcohol, intercooler, and good heads that increase efficiency to keep temps lower but probably yields the same power.

I've heard first hand from Ram/Dakota guys running no more than 10psi and putting over 20,000 miles on it. Some even higher, on their heavy truck. Keep it from overheating and you'll be just fine. IMO
 
a lifelong engine builder i know raced his well built 340 duster to best of 11.47.Stroked it to 372 changing absolutely nothing else it ran 10.47.Edelbrock heads,4.88 gears shifting at 7800.It wasn't long before he cracked a cylinder.
 
ir3333 said:
a lifelong engine builder i know raced his well built 340 duster to best of 11.47.Stroked it to 372 changing absolutely nothing else it ran 10.47.Edelbrock heads,4.88 gears shifting at 7800.It wasn't long before he cracked a cylinder.
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That brings up an important point about stock blocks. The cylinders were made for 275 HP or so, then we go and thin them by boring them out.
NHRA just allowed the aluminum race 6.1 block to be used in the 6.1 DragPak stock class cars because factory iron is almost non existent anymore. Horsepower went up dramatically with that change in my friends car.
 
gregsdart said:
Another thing to consider is the extra life added to a motor with a center weighted crank, which evens out the stress on the main bearings and webs, along with the crank itself. I run one in my 528 drag motor, and though expensive it was worth it. I had cap walk in a megablock, and the center weighted crank eliminated it from the # 2,3,4 mains. Add to that a better main cap and studs and I bet a stock block would tolerate more power than most would think.
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Could you explain "center weighted crank" First time hearing that term.......a link would be fine........... Is that just a fancy word for internally balanced crank???
 
There are guys on here like Crackedback that can tell you roughly what HP is required to run 10.47 in a mostly stock Duster ...and that is probably at or past the safe level for an LA block.
 
Cudafever said:
Could you explain "center weighted crank" First time hearing that term.......a link would be fine........... Is that just a fancy word for internally balanced crank???
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It literally means it has weights in the center, which are not used on cheap production or moderately priced cranks. Look at pictures of Mustang Gt (newer) cranks, some of them are center weighted.
A crank without the center weights has to use weight way out of line from the rods and positions in the center, which takes away the vibrations, but the bearings on the 2nd, 3rd and 4th mains have to take extra loads, and it puts stress on the crank,flexing it. The block has to transmit that balance force also,putting stress on it. Not too big a deal at low rpm, but as rpms go up, the loads go WAY up.
 
gregsdart said:
It literally means it has weights in the center, which are not used on cheap production or moderately priced cranks. Look at pictures of Mustang Gt (newer) cranks, some of them are center weighted.
A crank without the center weights has to use weight way out of line from the rods and positions in the center, which takes away the vibrations, but the bearings on the 2nd, 3rd and 4th mains have to take extra loads, and it puts stress on the crank,flexing it. The block has to transmit that balance force also,putting stress on it. Not too big a deal at low rpm, but as rpms go up, the loads go WAY up.
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Thank you for that!!!
 
Weight of the car is the big issue, a light car won't twist the block as soon as a heavy car. 2800 lbs vs 3800 lbs,which one is going to stress the parts more?
 
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