596 head performance mods

[moper]

Not that I've got hundreds under my belt.. but the cast crank stroker cranks, from virtually anyone, are desigend with performacne in mind. It's not like a factory cast crank. With better radii and the usual better balancing, these cranks run surprisingly well. One 416 with a solid roller, and Shady Dell CNC RPMs makes peak hp at 6200 peaking at 540 with the single 4bbl. Those heads flow no more than 280, possibly a hair less, and that's a mild street solid roller. Another 408 with the same CNC Shady Dells, but with some extra hand tweaking by a local pro flow 280 and that one makes peak power at 6500 with a peak of 550. that's a solid flat tappet, and it peaks at 530. That one also uses 175hp NOS kit to run 10.50s in street trim. Both of these are pump fuel. It does come down to cubic cash and honesty. If the car owner is honest with the builder, it isnt really tons more to get big power via more rpm. And th reason you get more power is every firing cylinder is X number of ponies, with so many pnoies in one minute. If you can get more firings per minute, you will have more power. My friend's Stock Eliminator 351 Cleveland used to leave at 6800, and shift at 7200. Even with the Autolite factory 600cfm carb. It wasnt making huge power up there, but it was making good power per power stroke, and had a lot more strokes per second, thus getting more power to the tires (and setting records). I dont use hypers in 4" engines, although I am considering them for a 390 for my truck. It never goes over 4000. But I do use factory rods that have been worked. The rods are the rpm limiter in those cases, and i say dont go past 5500. The decent (Diamond/Ross/Wiseco quality) forged pistons once you get them, are bullet proof to 7K+ wit 4" arms. So really, it comes back to heads. If the heads can move enough air, you'll make big power. Ryan gets huge hp numbers from his 400-450"small blocks as compared to big blocks because of the head choices. Aside from Hemis and Predators, there are no big block heads that can really move enough air for N/A Mopars.

 

[ramcharger]

Aside from Hemis and Predators, there are no big block heads that can really move enough air for N/A Mopars.

What about Indy's? If I (just for arguments sake) wanted to build a high rpm 400 ci screamer, I would choose a 383 or 400 B block and slap on a set of Indys, run a forged, knife edged crank, H beams and the lightest forged pistons I could get my hands on rather than run a stroker.

 

[moper]

The general rule is 2hp per cfm on a properly designed race engine. It's much less on a street or multiuse engine that has to operate over a wide rpm range. Most maxxed indys, and B1s, and Victors, will peak out around 350-400 cfm. There are versions that can go bigger, but they require a larger than factory bore due to valve size. I suppose Predators are a similar comparison to the 572-13 and 600-13 heads in terms of flow numbers, but those simply dont make the publicized numbers from the few I've heard about. I do know, there is no complimenting choice in intakes for these heads. They almost require sheet metal intakes or a ton of intake work to make the power Indy says. At least Predator is supposed to have a decent cast manifold available. I'll also toss out that I dont build anything with those parts. What I build are much different (as in not that hard core) and my info are friends or mentor's findings.
In terms of your idea, by keeping the smaller cubes and stroke short (3.38) you move the power peaks up in the rpm band. I wont build a B wedge bigger than 470 for several reasons.. One is the head and intake choices for double duty engines. You will make more power from smaller cubes and properly sized and matched ports, than bigger cubes and head that are too small.
If you look around, you can find race small blocks in the 408-440" and 4-4.25" stroke range making 700-800+ horsepower using heads that flow in the 300-380cfm range (W5/7/8). Easily reaching or exceeding the general rule. While race big blocks of 100 cubes more and similar strokes using heads that flow similar numbers are seemingly stuck at 650-750hp levels but usually 500 or so less rpms. They can barely reach that "rule of thumb" level.
My thought on this is the power robbing effects of having to exceed the rules of bowl shape and valve size vs. port volume due to block packaging is what makes that difference. You can only fit so large a valve in a round cylinder until it start to be detrimental.. and as the valve size is limited, the port's extra volume is useless. Look at the available curtain area of multi-valved heads and the port flow numbers and you can see when enough valve give enough volume the room it needs, you get monster power. Some imports I know have more cfms and 40% more curtain area available than the last 505" I did...lol. I read years ago about a Covalt Hemi head. It was a 4 valve head for wedge RBs. That... would be worth trying to find again.

 

[ramcharger]

The general rule is 2hp per cfm on a properly designed race engine. It's much less on a street or multiuse engine that has to operate over a wide rpm range.

Agreed!

Most maxxed indys, and B1s, and Victors, will peak out around 350-400 cfm. There are versions that can go bigger, but they require a larger than factory bore due to valve size. I suppose Predators are a similar comparison to the 572-13 and 600-13 heads in terms of flow numbers, but those simply dont make the publicized numbers from the few I've heard about. I do know, there is no complimenting choice in intakes for these heads. They almost require sheet metal intakes or a ton of intake work to make the power Indy says. At least Predator is supposed to have a decent cast manifold available. I'll also toss out that I dont build anything with those parts. What I build are much different (as in not that hard core) and my info are friends or mentor's findings.
In terms of your idea, by keeping the smaller cubes and stroke short (3.38) you move the power peaks up in the rpm band. I wont build a B wedge bigger than 470 for several reasons.. One is the head and intake choices for double duty engines. You will make more power from smaller cubes and properly sized and matched ports, than bigger cubes and head that are too small.

Agreed again, in my idea the B block would not be stroked at all, just use the aforementioned parts. I think the 800 hp could be achieved in naturally aspirated form in a 383/400 but it would have to screaming. 400 cfm in a head should do it. This would, of course be a strip only engine.

If you look around, you can find race small blocks in the 408-440" and 4-4.25" stroke range making 700-800+ horsepower using heads that flow in the 300-380cfm range (W5/7/8). Easily reaching or exceeding the general rule. While race big blocks of 100 cubes more and similar strokes using heads that flow similar numbers are seemingly stuck at 650-750hp levels but usually 500 or so less rpms. They can barely reach that "rule of thumb" level.
My thought on this is the power robbing effects of having to exceed the rules of bowl shape and valve size vs. port volume due to block packaging is what makes that difference. You can only fit so large a valve in a round cylinder until it start to be detrimental.. and as the valve size is limited, the port's extra volume is useless.

I'm curious as to your reasoning as a B block 383 has a 4.25 bore and a 400 has a 4.34 bore, far larger than could ever be achieved in LA block leaving far more room for larger valves than a stroker LA with similiar displacement.

Look at the available curtain area of multi-valved heads and the port flow numbers and you can see when enough valve give enough volume the room it needs, you get monster power. Some imports I know have more cfms and 40% more curtain area available than the last 505" I did...lol. I read years ago about a Covalt Hemi head. It was a 4 valve head for wedge RBs. That... would be worth trying to find again.

I know this well having build literally hundreds of motorcycle engines. Most acheiving well over 100 hp per liter.....@ 11,000+ rpm, lol! There is more surface area on two one inch valves than there is on one two inch valve. Multiple valves also tend to keep the intake velocity up as well. Yeah, that 4 valve wedge head would be an interesting find and one hell of a head to build a big block around.

..

 

[rumblefish360]

I'm curious as to your reasoning as a B block 383 has a 4.25 bore and a 400 has a 4.34 bore, far larger than could ever be achieved in LA block leaving far more room for larger valves than a stroker LA with similiar displacement.

Valve size, or more so installing a large one isn't the issue but more of the heads port and given size of the engine.

Moper was saying he likes to keep it @ 470 or less. I think that if your going passed that cube area, the head itself has an issue in flow/feeding the engine below.

Not to side step what moper was saying, it is good info in what he has done and found, but being a small block thread, it does have merit. But does it cross over well for anybody else reading. It's not exactly a apple to apple, but similar is good enuff here tonight.

So the question asked remains for some?

Does the 596 head hold enuff for a 4X4+ stroker engine?

I think it does (Can be) if the RPM ceiling isn't very high.

 

[moper]

Sorry Rumble, you're right, I got off topic.
Any 340/360 head will need porting to feed a well rounded 4" arm engine. By well rounded, I mean something that makes decent power from idle to 5500. The factory 360 stroke at 3.58 is 12% shorter. Simple math: "J", 915, 587, 596 heads will flow roughly 195-210 with a performance valve job. (190 to 203 is what I've seen w/1.88 or 2.02 intakes) so go 12% more than 203 and you're at 228cfm just to get stock performance from it. Most decently done bowl worked and gasket matched iron heads (a "stage 1" porting) will realistically reach 230 to 240, so when cammed with something that has good duration from .300-.500 lift they will work decently. They are small for the package in terms of volume, but they'll make 450+ real hp in the 5500 range. A "stage 2" type that will increase the volume a little bit will make more power in the 5500 range, and should carry it a little longer towards 5800-6K, depending on the head work (I'm looking for 260-270cfm), I'd expect to see 475-500hp with a bigger cam than the stage 1 version. I should also say the cams in question may not develop vacuum for brakes in a flat tappet design. Probably not with any form of roller either. The better the heads match the intended use and stroke, the more streetable things get. Meaning a good set of heads won't require as much cam to make more power. The issue now becomes cost. Most shops that offer it can wing a stage 1 job and not mess it up, and it adds a few hundred to the cost of the heads. Stage 2 or beyond takes more talent, and flow testing, and is generally double the cost of the stage one job. So now you're looking at irons that flow 250+ that cost $1700 ready to run. Edelbrocks with a decent valve job and maybe some blending with a sanding roll reach 250 for the same money, and give other benefits for the coin, plus, have room to grow to 280+. Those will carry a 4" arm to 6500, and make bigger power with smaller cams from 5000 rpm to peak.

 

[rumblefish360]

Moper, LOL, A slight off topic you may have gone, but the big block report (he he he) is still valid, no sweat IMo and also, IMO, good post.

 

[ramcharger]

Valve size, or more so installing a large one isn't the issue but more of the heads port and given size of the engine.

Thats not what Moper said, he said "You can only fit so large a valve in a round cylinder until it start to be detrimental.. and as the valve size is limited, the port's extra volume is useless."


Moper was saying he likes to keep it @ 470 or less. I think that if your going passed that cube area, the head itself has an issue in flow/feeding the engine below.

Ok, so an indy head flowing 400 cfm is insufficeint to feed a 499 B block stroker?

Not to side step what moper was saying, it is good info in what he has done and found, but being a small block thread, it does have merit. But does it cross over well for anybody else reading. It's not exactly a apple to apple, but similar is good enuff here tonight.

So the question asked remains for some?

Does the 596 head hold enuff for a 4X4+ stroker engine?

I think it does (Can be) if the RPM ceiling isn't very high.

I hope I don't sound like i'm trying to start an argument, I'm just trying to make sense of why a stroker small block in the 408-440 range would make more HP than B block with indy heads with the same (or close) displacement? I could see how it would make more torque in the street usable range but that's it.

Sorry Rob, I know I went way off topic here, I'm going to start another thread. http://www.forabodiesonly.com/mopar/showthread.php?p=424755#post424755

 

[rumblefish360]

I hope I don't sound like i'm trying to start an argument,

Ha ha ha ha, Fat chance. It's all good.

I'm just trying to make sense of why a stroker small block in the 408-440 range would make more HP than B block with indy heads with the same (or close) displacement? I could see how it would make more torque in the street usable range but that's it.

Mystery to me. Must be someting there I didn't cover in school. LOL

Sorry Rob, I know I went way off topic here, I'm going to start another thread. http://www.forabodiesonly.com/mopar/showthread.php?p=424755#post424755

Sorry ? Not to me. Great talkin goin on here. See ya on the new thread.