Magnum vs LA bash!

-
1

1wild&crazyguy

Banned
Joined
Jul 11, 2009
Messages
7,751
Reaction score
241
Location
Surrounded by mopar
Alright...so we know some of us here like to choose one over the other while some others could care less either way. This thread is for posting ur choice and reasons for liking one over the other and debating any advantage or disadvantage along with factual flow numbers and or casting defect experiences ......so post why you like or dislike the LA or MAGNUM enigines and or heads.

I know first hand that i can get well over 275cfm int flow out of a LA head, can you magnum guys get that from those thin cracking factory econo penny pinch heads called magnum heads?
:finga:
 
I've only seen the R/T head flow more than 275.

Are we speaking of stock heads only? Because that would disqualify the R/T head since it was never on any engine as delivered.

Otherwise, the 1.6 rocker over the 1.5 is nice. Not a end all.
I have not compared how fat the flow rates are down low between the 2 heads.
 
1wild&crazyguy said:
Alright...so we know some of us here like to choose one over the other while some others could care less either way. This thread is for posting ur choice and reasons for liking one over the other and debating any advantage or disadvantage along with factual flow numbers and or casting defect experiences ......so post why you like or dislike the LA or MAGNUM enigines and or heads.

I know first hand that i can get well over 275cfm int flow out of a LA head, can you magnum guys get that from those thin cracking factory econo penny pinch heads called magnum heads?
:finga:
Click to expand...

I was talking about STOCK long blocks. That means stock pistons, stock heads, not ported. swap in a cam, swap on an intake and carb and a set of headers. Im way to cheap and lazy to have anything ported.
 
Justin says LA heads are way better then Magnum heads. Most guys that run Magnum heads dont port them, They simply use them as an upgrade. He says the reason a stock Magnum motor makes more power is because they have Hyd roller cams.

LA roller motors were probably the lowest rated in power. How come ?

Magnum motors have more compression because of the chambers not because of were the piston sit in the whole.

Stock 5.9L cam is 249, 269 advertised duration and 410" lift
360 4bbls used the 340 cam.

stock Magnum "keg" intakes are terrible

Magnum compression 9:1
LA compression 8.4:1

hp ratings are 245hp and 335ftlbs for the mag

245 and 300 for the LA.

They look pretty even to me but the guys that have pretty much stock magnum motors with a few bolt on seem to be running deep 12s
 
and for what its worth, I like my cars to look stock so Id rather use the LA heads
 
In all the flow test I've seen stock magnums heads land inbetween 1.88 heads and X heads but don't gain as much as LA heads when ported, I think the magnum engine is a great deal for most people cause they make the most stock power and you can buy a running low K for $500-$800 the old 300hp create engine was a stock 5.9 magnum long block with a M1 dual plane and dyno 320hp with headers. If was building an engine from scratch and my choices were factory Magnum or LA heads I'd go with LA heads.
 
The magnum engine has a few advantages over the LA.. in stock form at least. The stock roller cam, means the flat cam problem is greatly reduced, they have more compression, less friction from the cam/lifters, 1.6 ratio rockers, as well as thinner lower drag rings, and they seem to be "sealed" better, as in the oil pan and valve cover areas. I put one ( 98 318 magnum) in my daily driver D100, and it has more power than the mid 70s la 318 I removed. I did use the dual plane carb intake and a thermoquad as well. As a matter af fact, I feel that pulls almost as hard as a worn out 71 340 that was in there for a breif amount of time. As far as building them all out, I dont know.
 
Gen 3 Hemi, it's a small block :twisted:
Stirring the pot a bit.
 
we took a stock 8.7 compression magnum engine out of a 95 van put the same cam and intake out of the 380HP crate engine put it in a 67 a-100 truck with a 727 3500 stall and it has run a best of 12.71 at 106 3300lbs and the worst aerodynamics you can get worse then trying to push a peice of plywood in the wind. And that was when eveything for the mangums was super exspensive cost a $1000 for intake and cam.

By far the most reliable engine i have seen it sits outside all winter long hit the key and fires right up its been through about 15-20 sets of rear tires its hit 7500rpms multible times we built this thing to be a toy and it gets used and abused rode hard and put away wet and it dont seem to care only thing we have had to replace is some u-joints and one trans from multible burnouts and multible sets of tires.

My opinion its the cheapest 12sec smallblock out there
 
AdamR said:
Justin says LA heads are way better then Magnum heads. Most guys that run Magnum heads dont port them, They simply use them as an upgrade. He says the reason a stock Magnum motor makes more power is because they have Hyd roller cams.

LA roller motors were probably the lowest rated in power. How come ?

Magnum motors have more compression because of the chambers not because of were the piston sit in the whole.

Stock 5.9L cam is 249, 269 advertised duration and 410" lift
360 4bbls used the 340 cam.

stock Magnum "keg" intakes are terrible

Magnum compression 9:1
LA compression 8.4:1

hp ratings are 245hp and 335ftlbs for the mag

245 and 300 for the LA.

They look pretty even to me but the guys that have pretty much stock magnum motors with a few bolt on seem to be running deep 12s
Click to expand...

Those keg intakes make lots of torque actually...
And 1.6 rockers accelerate the valve opening....But again...its not the heads flow
 
I run all my mopars hard and they have no issues, that's one f the reason I run them, has nothing to do with mag heads, they both are the same in the bottom end depot.
If u equip the la with all the stuff a mag has in the 1.6 rocker, roller cam and heck...go ahead and leave closed chambers out of it, the La would make more power and rev higher do to better flow and more port volume. As for numbers off of sites comparing the two, all garbage to me...I have flowed heads the same casting from the factory and see better numbers than what's reported, I consider the valve job they do on these tester heads...that makes a huge diff in low lift and peak numbers. I have seen heads with factory v jobs do better than the same head after a run of the mill v job. Consider that people.
 
1wild&crazyguy said:
I run all my mopars hard and they have no issues, that's one f the reason I run them, has nothing to do with mag heads, they both are the same in the bottom end depot.
If u equip the la with all the stuff a mag has in the 1.6 rocker, roller cam and heck...go ahead and leave closed chambers out of it, the La would make more power and rev higher do to better flow and more port volume. As for numbers off of sites comparing the two, all garbage to me...I have flowed heads the same casting from the factory and see better numbers than what's reported, I consider the valve job they do on these tester heads...that makes a huge diff in low lift and peak numbers. I have seen heads with factory v jobs do better than the same head after a run of the mill v job. Consider that people.
Click to expand...
Does it all just come down to prep work?
 
The only thing that's keep the LA 360 back is its CR cause if you found a low K 2bbl 360 and threw on 750, air gap, headers the only problem is the low CR when choosing a cam but if raised the CR you would have a similar performing engine.
 
273 said:
The only thing that's keep the LA 360 back is its CR cause if you found a low K 2bbl 360 and threw on 750, air gap, headers the only problem is the low CR when choosing a cam but if raised the CR you would have a similar performing engine.
Click to expand...


but thats part of the reason guys switch to Mags. The closed combustion chamber raises the compression. Both blocks use the same compression height piston and both have the same deck height.
 
From what I understand the Magnums have better low-lift flow and a bit more "area under the curve" if you know what I mean but the LAs (from what 1wild&crazyguy's saying) have better higher-lift flow and take better to porting... The cool thing with the closed chambers is being able to run higher compression on pump gas. My stock-Magnum-headed 360 has 10.42:1 static compression and 8.71:1 dynamic and it runs fine on mid-grade gas for most street driving; I put premium when I know I'll be driving hard and there is no detonation unless it's sunny and over 90* outside and I floor it in 3rd gear. My converter is pretty loose (cheap 2800 RPM TCI or something) which kills gas mileage but I bet with an overdrive manual and 3.23 gears it would pull low-mid 20s no sweat. The torque is massive with the small Voodoo cam and 1.6 rockers.

Big question: would I do it again? Probably not, mainly because A) most factory Magnum heads are cracked, B) good 360 LA heads (308, X, J) aren't much worse flow-wise, and C) new aftermarket ones like the RHS and EQ Magnums are just soooo much more of a value at the end of the day esp. if you want to upgrade more in the future (porting, big valves, etc.)
 
Magnum heads are better. They have closed chambers that need less ignition timing, have dual quench areas, and less cc volume yielding more compression. The intake port although slightly smaller in cc volume flows more air = MORE PORT VELOCITY. The exhaust port is vastly better than the majority of LA heads (the 308 is very close but still not as good). The valves have lighter 5/16 stems and single bead lock grooves as compared to heavy 3/8 stems and multi groove locks for the LA, this greatly improves the engines ability to rev without valvetrain stability and durability issues. The Magnum valves have superior flow shape. The intake is a 13* nailhead with no ski jump on the back, the exhaust is a 22* tulip again with no ski jump on the back. LA valves are the opposite. Every LA head to come through the shop has needed the exhaust guides redone usually both. Magnums, never needed to put guides in one yet. Lets talk rocker arms. Magnum has a true 1.6 ratio, LA usually around 1.4. Anyone who's raced an LA motor with the OEM stamped rockers knows it don't take long before you punch a pushrod through one. Never seen a Magnum rocker fail (yet). Head cracking, being the guy who runs the magnuflux equipment at the shop I can tell you that both LA and Magnum heads are terrible for cracking. 50/50 for both families on this, . I take a beating from the Chiby guys at the shop for that all the time, if I hear one more Mopar crackhead joke I'm kickin some ***. Intake manifolds obviously the Magnum doesn't have as many choices, but the one that works best 99% of the time for the LA is also made for the Magnum, the RPM AirGap.
Short block wise the Magnum is better also. The pistons are lighter weight hyperuetectic not heavy cast. They carry 1.5mm/1.5mm/4mm low tension rings as opposed to 5/64 5/64 3/16 standard tension rings. They sit higher in the bore by about .020 " IIRC. The rods are also lighter weight (narrower at pin end) and better quality forgings. The factory block casting quality is much improved over the LA, although I've noticed they sonic check thinner. The deck height has been spot on side to side, front to back on every one I've checked so far, older LA never even close (late 80s early 90s roller blocks have all been good though). Oiling system is a little better, oil feed passage from lifter galley to the mains is bigger, oil filter plate has 6 holes vs 4 (just drill more holes). Magnum has hyd roller cam vs LA hyd flat tappet, definitely a plus. Magnums being EFI motors will usually be in good condition even with high mileage unlike an LA that with as little as 50k are in need of a ring and bearing overhaul at least. As mentioned earlier the Magnum motors seal up much better (the 3 Mag cores sitting in the shop right now are nearly bone dry).
Disadvantages IMO are that you'll need an LA front cover, a pass car oil pan/pickup, and an LA distributor.
 
You can look at peak numbers all day long. You may as well swordfight with your peepee's.

It's the hp and torque area under the curve that matters, and the Magnum's roller cam with associated fat cam lobe, and 1.6 rocker arms give it a tremendous advantage, all else being equal. Yeah, the beer barrel intake sucks for power, but torque is what makes a street motor fun, and that's what beer barrels do...make things fun :)

I'll take the poor-flowing Magnum heads, non-wiping cam, and free lift rocker arms anyday, and a set of EQ heads goes a long ways. Plus serpentine belts, 30+ years of metallurgical refinement, billions made and ripe for picking. Magnum, hands down, and all I'll run from now on, unless I get into new Hemi swaps.
 
I contacted Wild ,to do my Magnum head porting,after this thread he lost work.Tired of blowhards.
 
Abodybomber said:
I contacted Wild ,to do my Magnum head porting,after this thread he lost work.Tired of blowhards.
Click to expand...

Oh well, and if you ever need a surgeon, you might not agree with all of his views but he just might still save your life.

If you need some heads ported, just care about how good of a job he will do and forget the rest
 
You must log in or register to reply here.
-

Back
Top