There are a lot of reasons why small block Mopars SHOULD have outrun Chevy V8 small blocks over the years... To name a few:
Superior design features, like:
Valves centered in the cylinder (Chevys are not)
Larger diameter lifters (better valve actuation)
Longer rods (better cylinder filling)
Usually, bigger valves
18-degree valve angle STOCK (Chevys were 23-degree, I believe)
Bigger bore (Chevy never had a 4.040" bore like a 340, without siamesed bores)
Shaft-mounted rockers
"Cool fuel" (Thermoquads)
Better automatic transmissions
I'm sure there are a lot more reasons; I just can't think of them right now.
But, generally speaking, they have played second fiddle to the Bow Tie, a decidedly inferior engine, throughout the years. Look at the NHRA records....
When I ask myself "WHY?" I can only see two reasons for this anomaly.
To wit: The reciprocating weight of a rotating assembly (including rods, pins, pistons, and crank) of a 340 motor will outweigh a 350 Chevy by a bunch.
I think the 340 crank, alone, is about 5 pounds heavier than a 350 Chevy.
Unless you want to buy lighter aftermarket components that are designed to weigh less (and, you surely can do that), you're stuck with a heavier reciprocating assembly that will eat up more horsepower than the Chevy, just turning itself over... and is harder to accelerate from low rpm's to high.
But, I think the REAL reason for our favorite 340's and 360's playing second fiddle to the Bow Ties is in cylinder head air flow.
Granted, W-2's and specialty (Edelbrock, etc.) non OEM heads can be had that can turn the L-A and Magnum small blocks into Chevy's worst nightmare (screamers,) but the really good ones usually entail buying a lot of necessary, but "different" hardware (longer valves, different headers, special rocker arms, dedicated intake manifolds, etc) that can run the cost of this hi-performance system up to a figure that the average, Joe who's building a street/strip car, can't justify spending.
Indulge me just a bit here; I apologize for the length....
Back in the '70s, when Pro Stock was in its infancy, there was a team of AMC guys(Waly Booth and Dick Arons) who wanted to be competitive with an AMC Hornet, but none of the AMC heads flowed enough air.
They took two cast iron V8 heads and made one TALL head by cutting one horizontally, a little above the halfway point, and the other head a little below the halfway point. The put the two "tall" halves together and ended up with a head that was about 3/4" taller than a stock head. I'm not sure if 3/4" is correct, but, you get the idea...
They performed an acetylene marriage between the two, built a matching head for the other side, and SHAZAM.... It was so fast that NHRA BANNED "welded" heads after they showed how well it coud run by winning a bunch of races with it.
The G.M. heads that go onto their newer small block LS series of motors (based on the aluminum Corvette motor) have very tall ports.... The Cadillac Escalade has a derivative of that Corvette engine; I think it's called an LQ9, maybe (not sure), but Car Craft has tested that motor/head combination and determined that those heads (and, they ARE classified as small block (LS series) heads,)flow over 300-cfm, right out of the box!!!
The heads we get excited about for our 340s/360s don't generally flow anywhere near that much. Sometimes, even the ported versions don't flow that well.
The regular OEM L-A and Magnum heads have an "Achilles heel," it seems to me; the narrow area where the intake ports pass the pushrods.
I know that the T-A heads have offest rockers and the ports can be somewhat wider, and the W-2's are better, yet, but now we're into specialized valve train hardware just to get a decent-sized intake port. And, there's no "wide-port Mahnum head at all... that ~I~ know of. Correct me, please, if I'm wrong.
As you know, there are now companies making aftermarket heads for L-A and Magnum small block Mopars. THis new head from Hughes (can't remember who casts it) is another addtion to the varriety of heads available, along with the aluminum ones from Edelbrock. That's good.... great, in fact.
But, with all this activity, and the improvements they have made, they still are MILES away from the heads on a STOCK Cadillac Escalade... which are aluminum, but otherwise, not much different from the larger (but still small block) Chevy TRUCK motor heads.
What I'm thinking is, why not a NEW L-A/Magnum head that is TALLER (since we can't go WIDER) so that the volume of the intake ports can be significantly larger, in a move like the AMC boys did nack 35 years ago...
The intake manifold would have to be a one-off design with taller ports, but the header flange pattern could remain the same. I don't want to have to buy a new set of TTI's just because I put a better intake port on my motor...
About the only thing that would need to change would be the intake manifold (and gaskets), head-bolt length, pushrod length, and valve length.
Sure, it would take a lot of engineering on somebody's part, but I'd bet with a 3/4" increase in port height, (and, no other changes), air flow through the intake port would increase by a SIGNIFICANT amount! Maybe to over 300 cfm. Wouldn't THAT be nice????????????
I would hope that someday, down the road, one of these aftermarket Mopar cylinder head manufacturers would get a clue and eliminate that bottleneck (the too-close-together pushrods) and build a "TALL" small block Mopar head for the masses.
An engine so equipped would probably run ALL OVER a Chevy V8.
I can't wait........
Bill, in Conway, Arkansas
Superior design features, like:
Valves centered in the cylinder (Chevys are not)
Larger diameter lifters (better valve actuation)
Longer rods (better cylinder filling)
Usually, bigger valves
18-degree valve angle STOCK (Chevys were 23-degree, I believe)
Bigger bore (Chevy never had a 4.040" bore like a 340, without siamesed bores)
Shaft-mounted rockers
"Cool fuel" (Thermoquads)
Better automatic transmissions
I'm sure there are a lot more reasons; I just can't think of them right now.
But, generally speaking, they have played second fiddle to the Bow Tie, a decidedly inferior engine, throughout the years. Look at the NHRA records....
When I ask myself "WHY?" I can only see two reasons for this anomaly.
To wit: The reciprocating weight of a rotating assembly (including rods, pins, pistons, and crank) of a 340 motor will outweigh a 350 Chevy by a bunch.
I think the 340 crank, alone, is about 5 pounds heavier than a 350 Chevy.
Unless you want to buy lighter aftermarket components that are designed to weigh less (and, you surely can do that), you're stuck with a heavier reciprocating assembly that will eat up more horsepower than the Chevy, just turning itself over... and is harder to accelerate from low rpm's to high.
But, I think the REAL reason for our favorite 340's and 360's playing second fiddle to the Bow Ties is in cylinder head air flow.
Granted, W-2's and specialty (Edelbrock, etc.) non OEM heads can be had that can turn the L-A and Magnum small blocks into Chevy's worst nightmare (screamers,) but the really good ones usually entail buying a lot of necessary, but "different" hardware (longer valves, different headers, special rocker arms, dedicated intake manifolds, etc) that can run the cost of this hi-performance system up to a figure that the average, Joe who's building a street/strip car, can't justify spending.
Indulge me just a bit here; I apologize for the length....
Back in the '70s, when Pro Stock was in its infancy, there was a team of AMC guys(Waly Booth and Dick Arons) who wanted to be competitive with an AMC Hornet, but none of the AMC heads flowed enough air.
They took two cast iron V8 heads and made one TALL head by cutting one horizontally, a little above the halfway point, and the other head a little below the halfway point. The put the two "tall" halves together and ended up with a head that was about 3/4" taller than a stock head. I'm not sure if 3/4" is correct, but, you get the idea...
They performed an acetylene marriage between the two, built a matching head for the other side, and SHAZAM.... It was so fast that NHRA BANNED "welded" heads after they showed how well it coud run by winning a bunch of races with it.
The G.M. heads that go onto their newer small block LS series of motors (based on the aluminum Corvette motor) have very tall ports.... The Cadillac Escalade has a derivative of that Corvette engine; I think it's called an LQ9, maybe (not sure), but Car Craft has tested that motor/head combination and determined that those heads (and, they ARE classified as small block (LS series) heads,)flow over 300-cfm, right out of the box!!!
The heads we get excited about for our 340s/360s don't generally flow anywhere near that much. Sometimes, even the ported versions don't flow that well.
The regular OEM L-A and Magnum heads have an "Achilles heel," it seems to me; the narrow area where the intake ports pass the pushrods.
I know that the T-A heads have offest rockers and the ports can be somewhat wider, and the W-2's are better, yet, but now we're into specialized valve train hardware just to get a decent-sized intake port. And, there's no "wide-port Mahnum head at all... that ~I~ know of. Correct me, please, if I'm wrong.
As you know, there are now companies making aftermarket heads for L-A and Magnum small block Mopars. THis new head from Hughes (can't remember who casts it) is another addtion to the varriety of heads available, along with the aluminum ones from Edelbrock. That's good.... great, in fact.
But, with all this activity, and the improvements they have made, they still are MILES away from the heads on a STOCK Cadillac Escalade... which are aluminum, but otherwise, not much different from the larger (but still small block) Chevy TRUCK motor heads.
What I'm thinking is, why not a NEW L-A/Magnum head that is TALLER (since we can't go WIDER) so that the volume of the intake ports can be significantly larger, in a move like the AMC boys did nack 35 years ago...
The intake manifold would have to be a one-off design with taller ports, but the header flange pattern could remain the same. I don't want to have to buy a new set of TTI's just because I put a better intake port on my motor...
About the only thing that would need to change would be the intake manifold (and gaskets), head-bolt length, pushrod length, and valve length.
Sure, it would take a lot of engineering on somebody's part, but I'd bet with a 3/4" increase in port height, (and, no other changes), air flow through the intake port would increase by a SIGNIFICANT amount! Maybe to over 300 cfm. Wouldn't THAT be nice????????????
I would hope that someday, down the road, one of these aftermarket Mopar cylinder head manufacturers would get a clue and eliminate that bottleneck (the too-close-together pushrods) and build a "TALL" small block Mopar head for the masses.
An engine so equipped would probably run ALL OVER a Chevy V8.
I can't wait........
Bill, in Conway, Arkansas
