Small block strength

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I know that mopar small block cranks are very strong,even the cast ones will hold up to the 500-550 h.p level. I think the blocks are pretty good too,as mopar saw fit to make thier stuff over engineered and used high nickel content in all thier blocks.

The king of the mopar blocks has to be the 400,some of them are able to endure the 800 h.p level. Sort of ironic that the lowly 400 smog motor has the best potential.
 
I have a '92 B350 van with a 360LA roller and it has the "308" heads on it. I bought it mainly for the A518/46RH tranny but will use the motor in a '71 Duster I picked up earlier this year.

Chuck
 
I've been running a 1975 360 block that's stroked to 415, cast crank internally balanced with about 450 horse. Engine is 5 years old now and still running 11.50s. I was told by the engine builder that the 360 blocks are safe to 500hp without mods. Jayson
 
jysnflem said:
I've been running a 1975 360 block that's stroked to 415, cast crank internally balanced with about 450 horse. Engine is 5 years old now and still running 11.50s. I was told by the engine builder that the 360 blocks are safe to 500hp without mods. Jayson
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Well, there are a lot of different ways to get 500 HP out of a 360, and that makes me wonder if some are easier on the block than others.

For example, you could have a "screamer" 360 with ported w-2 heads, some 13:1 forged pistons, a single plane manifold with a 750 double pumper, 1-3/4" headers, a solid roller cam, turn it 6,800 RPM and easily make 500 PLUS horsepower... maybe 600...:cheers:

Or, a 408 stroker with 12:1 pistons, Edelbrock aluminum heads, an 850 Holley, big tube headers, and a stout, hydraulic roller cam, and make 500+ HP at 6,000 rpm...

Or, and engine like mine; basically stock short block and heads, with a mild Hughesperformance hyd. roller, a 750 blow-thru Holley on an Air-Gap-style (Chinese clone) intake, TTI headers, and make 500+ HP at about 5,500 RPM with 10 pounds of Vortech-inspired boost...

Or, use a mildy spec'd, but forged component (crank; pistons; rods) 360 with a 250 shot of nitrous and get 500 HP... at probably less than 6,000 rpm.

Lots of ways to skin that cat, but which are harder on the block, or are they all pretty much the same at a 500 HP level???

Just askin'.... I have NO IDEA! :angry7:
 
Boost is hardest. Belt driven superchargers are the hardest on the block and crank because the resistance to the belt. The pulley is on the snout, outside the main caps and that means the crank has otrsional stress and lateral stress from the resistance. That's one of the reasons turbo engines make more power with similar boost curves. Turn the blower by hand and you'll see how hard it is to spin at a few rpm. Now think about what it does at 5Krpm. NOS is harsh but only when there's a tuning issue. 500hp is easy to get NA, and factory blocks will live with careful prep.
 
moper said:
Boost is hardest. Belt driven superchargers are the hardest on the block and crank because the resistance to the belt. The pulley is on the snout, outside the main caps and that means the crank has otrsional stress and lateral stress from the resistance. That's one of the reasons turbo engines make more power with similar boost curves. Turn the blower by hand and you'll see how hard it is to spin at a few rpm. Now think about what it does at 5Krpm. NOS is harsh but only when there's a tuning issue. 500hp is easy to get NA, and factory blocks will live with careful prep.
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Thanks, Moper; I'm sure all of that is true. Given that, to get the same power from a 408, for example, what would you think might be the hardest on a forced induction engine; a centrifugal supercharger (such as a Vortec; Powerdyne, or Pro Charger) or a positive displacement, roots type or twin screw, all making 10 pounds of boost? Is there any difference, or is "boost" just "boost" when it comes to producing it???

Turbochargers and a different issue. They're hard on parts (because of the backpressure and heat, ) but not necessarily, the block, per se.

Thanks for your good information and opinions, Moper!!!

Anyone else have info they'd like to share on this?
 
As far as which is hardest? I'm just guessing here but I'd say the roots style positive would be because they produce the same amount of pressure from every turn, loading the crank immediately. Where the centrifical has to spin up like a turbo does to really produce max boost. Plus the roots style is not s steady pressure, but has pressure spikes as the pressure areas of the rotors are sealed and exposed. Just a guess tho...
 
stock 340/ 360 blocks are good to the 500 to 550 hp level, much more than that your pressing your luck, they have a tendency to split in the lifter valley area. that said their are many guys running 600 + with stock blocks but for how long?
 
there is no way the build a stroker right on a budget $5000.00 to 6500.00 depending what kit you use and what heads i put a 416 together and have about 7500. in it and i put it together
 
Bill Dedman said:
Thanks, Moper; I'm sure all of that is true. Given that, to get the same power from a 408, for example, what would you think might be the hardest on a forced induction engine; a centrifugal supercharger (such as a Vortec; Powerdyne, or Pro Charger) or a positive displacement, roots type or twin screw, all making 10 pounds of boost? Is there any difference, or is "boost" just "boost" when it comes to producing it???

Turbochargers and a different issue. They're hard on parts (because of the backpressure and heat, ) but not necessarily, the block, per se.

Thanks for your good information and opinions, Moper!!!

Anyone else have info they'd like to share on this?
Click to expand...

Do you have Corky Bell's book,Maximum boost"? There is a very in depth explanation as to why turbo boost is very easy on the engine. It makes sense While staying in "laymans" terms".

The short of it is that many manufacturers build and warrantee turbocharged motors.

The long of it is that the boost is less at the top of the stroke and at it's most at bottom. The pressure build up is spread out and the chamber volume increases with the boost.

As for strokers,many of them alter factory engineering parameters like rod ratio and angularity,resulting in higher side loads to the piston and cylinder and increased piston speed.While this does make more torque and h.p it comes with the above price.

Nitrous cooks pistons and rings,not to mention nitrous backfires that can destroy your car.Leave it for the racers. A stroker is a better investment.
 
I think it's kind of a toss-up on costs, normal-aspirated with a stroker, vs. a stock-displacement 360 with a turbo or a blower.

You end up with about the same amount of power, and I think the cost is pretty much the same. The turbo would probably be somewhat more powerful, of the 3.

With a stroker, you need better heads, somewhat better quality, different, pistons and rods (plus, the cost of the crank, of course), but with a blower, you maybe can get by with inferior heads, but you have to have forged pistons, better rods, and a blow-thru carb (mine was $900.00 from the Carb Shop).... and of course, the cost of the supercharger.

Both systems would need fuel system upgrades, but the stroker system could be a lot cheaper; (no boost-referenced pressure regulator.)

The one advantage of a supercharger is that driveability can be very driver-friendly, because valve overlap can be at a minimum. My stock bore and stroke, 360 Magnum engine makes a little over 500 flywheel HP, but has a cam that is exceedingly mild; 214/218 @ .050" lift, and as a result, idles like a 318 2bbl at 475 rpm, and makes 12 inches of vacuum for the brake booster at that rpm.

The downside is, if I want to realy get on it, and utilize my avaialble,10 pounds of boost, I have to run some really good gas; pump gas would detonate RIGHT NOW, with my setup, so going fast with my Vortech requires some expensive gas.... if I want it to live.

Most people wouldn't want to mess with that, I am sure...
 
needsaresto said:
Do you have Corky Bell's book,Maximum boost"? There is a very in depth explanation as to why turbo boost is very easy on the engine. It makes sense While staying in "laymans" terms".quote]

As a matter of fact, I do own that book, but I found it to be lacking in worthwhile information about centrifugal superchargers, which is what I have, so I gave it short shrift...

Perhaps I need to pay more attention and give it another chance; I might learn something!

Thanks for the heads-up!!! :read2:
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len340 said:
there is no way the build a stroker right on a budget $5000.00 to 6500.00 depending what kit you use and what heads i put a 416 together and have about 7500. in it and i put it together
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This totally depends on what you can find used or may have laying around. I bought an Eagle 4.00 stroke cast crank used in excellent shape for $100 (friends are good to have, gear head friends are even better). I had 6 Eagle H-beam rods from a previous engine, got two matching ones for $100 from Eagle some time back. And I traded a 904 tranny shield and flex plate shield that I couldn't use in my car for a 72 360 standard bore block. You can buy Probe forged stroker pistons or KB forged stroker pistons for under $500 if you shop around.

The rest of the build is going to cost about the same regardless of what you build.
 
Bill Dedman said:
needsaresto said:
Do you have Corky Bell's book,Maximum boost"? There is a very in depth explanation as to why turbo boost is very easy on the engine. It makes sense While staying in "laymans" terms".quote]

As a matter of fact, I do own that book, but I found it to be lacking in worthwhile information about centrifugal superchargers, which is what I have, so I gave it short shrift...

Perhaps I need to pay more attention and give it another chance; I might learn something!

Thanks for the heads-up!!! :read2:
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Your welcome! I think I understand why you didnt give it much attention,as it really is aimed at the guy building a turbo system from scratch.
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Here's my build: 408 Stroker , short block built by Hughes Engines

-Forged internals, H-beam rods, 10:1 pistons
-Hughes Engines main stud girdle
-7 qt moroso pan, high volume melling oil pump
-Edelbrock heads, with Hughes Engines stage III porting, 2.05 intake, 1.60exh
-Hyd. roller cam. 576/576 lift int/exh. 256/258 deg. duration
-edelbrock victor 340 manifold, gasket and port matched to heads
-750 Mighty Demon carb
-Hughes Engines 1.6 Aluminum roller rockers
-Gear Drive, w/ custom timing cover and electric water pump
-TTI 1 5/8" - 1 3/4" Headers

Dyno'd @ 532 HP/520 FT. LBS
 
I like your approach; I just can't afford it...

Hughes seems to do things right ( have a Hughes cam in my engine), and you certainly have a worthwhile piece there... 532 HP on pump gas.... And, it will probably live, forever!

Congratulations on putting together a well-thought-out, workable powerplant that has a LOT of grunt!!!!:cheers:

I'm sure it wasn't cheap, but what quality merchandise IS????


Thanks for sharing with us!!!
 
mopardude318 said:
-Hyd. roller cam. 576/576 lift int/exh. 256/258 deg. duration

-Hughes Engines 1.6 Aluminum roller rockers

-Gear Drive, w/ custom timing cover and electric water pump
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Could you shed some light on these parts?

The Hyd. roller cam, is that the lift as ground or with the 1.6 rockers?
On the heads, did they have to modify the spring seat? And machine them deeper? There valve springs are used I can assume?

Tell me anout the gear drive and mods please. I'm very interested in this. Who's it is and what was needed to be done.
 
rumblefish360 said:
Could you shed some light on these parts?

The Hyd. roller cam, is that the lift as ground or with the 1.6 rockers?
On the heads, did they have to modify the spring seat? And machine them deeper? There valve springs are used I can assume?

Tell me anout the gear drive and mods please. I'm very interested in this. Who's it is and what was needed to be done.
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OK, I was a touch off on the cam. I looked at the sheet and here's what I got:
Camshaft Technical Details

Intake Valve Lift 1.5 .540"
Exhaust Valve Lift 1.5 .540"

Intake Valve Lift 1.6 .576"
Exhaust Valve Lift 1.6 .576"

Intake Duration at .050" 252°
Exhaust Duration at .050" 258°

Lobe Separation Angle 114º
Intake Opening at .050" 15° BTC
Exhaust Opening at .050" 66° BBC

Intake Closing at .050" 57° ABC
Exhaust Closing at .050" 12° ATC

Min. Suggested Cylinder PSI

Sweet Spot RPM 2100 - 7100

I am using the 1.6 roller rockers.

On the heads I was off as well, Heres what they are:

Stage 3 CNC Ported Heads with 2.08" Valves http://www.hughesengines.com/Index/...ZXIgSGVhZHM=&level2=QWx1bWludW0=&partid=25511

The Gear Drive is from Milodon:
http://www.summitracing.com/parts/MIL-13600/

We had to drill another mounting hole in the front of the block, using the bracket as a template.

The billet aluminum timing cover is from MagnumHP. I don't think they have it listed on their website. You will have to call or email them.
 
Well as it just so happens I found a 400 B in a 77 Newport at local junk yard, but it's not an early block with thicker mains. I also found multiple 318 LA roller cam motors (but no 360s) and some A-518s for the OD which I really like for a daily driver. Of course no idea on their conditions, but what should I even consider in my '69 Dart. The 400 would fit ok since it's a short deck big block, right? But where's an OD auto that will fit it?
 
There isn't any factory auto OD for the big block. What you can do is contact JW Performance Transmissions in Rockledge Florida. He makes NHRA accepted and SFI approved bell housings called the UltraBell. You can get one of these for a 727 to BB Mopar and it will fit the 518 or 46RH.

http://www.racewithjw.com/
 
OleNatesOlds said:
Believe me if I find an early 400 that's not bored out crazy, I will grab that puppy over a small block and then it's a different topic. Yet, it looks like 360s are going to be the most abundant candidates around here. So if that's the case, I'm looking to make 400 RRRWHP (Reliable, rock-solid, rear wheel HP!) for years to come. Normally aspirated, street driven mostly, pump gas, enough vacuum for brakes, carb or EFI?. I wanted to leave induction vague because I don't know if the Magnum system can support that or if it requires major mods. I do like the factory roller cam in it. If they are generally beefier, can pre-mag blocks be retrofitted with magnum components?
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if your only looking for 400 hp then any of the small blocks are fine. just use good parts and fasteners. i would go 89-up 360. they are roller motors and easy to use roller cams in. magnum or pre magnum i really don't thing it matters these days...
 
OleNatesOlds said:
Well as it just so happens I found a 400 B in a 77 Newport at local junk yard, but it's not an early block with thicker mains. I also found multiple 318 LA roller cam motors (but no 360s) and some A-518s for the OD which I really like for a daily driver. Of course no idea on their conditions, but what should I even consider in my '69 Dart. The 400 would fit ok since it's a short deck big block, right? But where's an OD auto that will fit it?
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a late 400 block will be fine for 400 hp. all that early thick crap was magazine hype years ago.
 
abodyjoe said:
a late 400 block will be fine for 400 hp. all that early thick crap was magazine hype years ago.
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Truth be told the late 400 low deck is one of the strongest castings ever made by Mopar.It is also blessed with the largest bore size of all the mopar blocks In stroker form with aftermarket heads a 400 block can crank out 700 to 750 h.p no problem.
 
I like my 340, only problem it had was the guy before me built it wrong so no i spent 2 k fixing his mistakes. Its been fun though.
1973 340
241 @ 241 cam
Hyper Pistons @ .040 o/s
Edelbrock 700 cfm
K&N air cleaner
Wix oil filter
Mobile one oil
Hydraulic Lifters
360 J heads 2.02 in 1.62 ex milled

Just the normal stuff lol

The guy helping me is a racer with a Chevy 421 sb on methynol @ 1/8 mi in 6.200 sec @ 110 mph
He said my car 65 Barracuda should do the 1/4 in mid 13's so....
 
a late 400 block will be fine for 400 hp. all that early thick crap was magazine hype years ago.
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Your statement is partially backed up by this article:

http://www.440source.com/blockinfo.htm

but I'm also referring to their pics concerning main bearing support which is more my concern from messing with Olds motors and have seen some nasty outcomes from lack of support. Still that's in the realm of racing situations mostly which is not really my concern for a street/strip motor. Can anyone comment on the article based on personal experience? (I know I'm starting to hijack this forum since it's supposed to be about small blocks) Is searching for a pre-72 400 block just looking for a unicorn, cuz let's face it: unicorns are stupid...
 
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