Lets talk about Hemi's, Cat's meow ? myth ? both??

[63 Nitrous Ratt Vette]

I am pretty much a die hard Chevy guy, but am more beholden to fact than I am the Bowtie. I have some friends that are die hard Mopar guys. To hear these guys talk you would think God himself invented the hemispherical combustion chamber. I know that in the late 60's they were a cutting edge deal, but I believe by today's standards they are archaic technology.

For the purpose of discussion I am referring to the Mopar Hemi's, or after market Mopar hemi style heads, Stage 5 heads for example, not the Chemi.

Cons:
Huge heavy pistons
Huge extremely inefficient combustion chambers
Very long rods
Opposed valves that do know allow really large camshafts
Very wide blocks that are a terrible transition from intake to heads.
Beefy overly large mains

Pros:
Flow #'s that are extremely good
Symmetrical ports
Beefy internals

I am not looking for guys to necessarily agree or disagree, just looking for facts and discussion.

Thanks,
John

[hsutton]

If NHRA hadn't made a class for the SS/AH and SS/AAH cars exclusively we'd have been able to see how well they would have done against modern technology. The new 505 H.P. Corvette would surely have given them something to run against if NHRA and mother Mopar hadn't stepped in. The LS-7 might not have been able to knock them off but then again maybe it could have. The older ZL-1 Corvettes are getting pretty fast but probably need a second carb and tunnel ram to be a dead heat with the Hemi cars.

[Cobra]

A huge hurdle is presented each time a piston rises in a Hemi and blocks flow in the combustion chamber. Old Pro-Stock cars and new Hemis use two plug per cylinder designs to help combat this. A four-valve per cylinder, OHC head, with a centrally located plug is a much better design. The bad news is that the two-valve "wedge" head has about run its course. If I were to design a BBC head it would involve four valves per cylinder and overhead cams. This design would solve a lot of problems with current designs.

[SchmidtMotorWorks]

Beefy overly large mains

IIRC, BBC Mains are the same dia and wider

[SWB]

I just don't think that you'll ever get the type of combustion out of a true hemi head as you can out of a canted valve head with actual and effective squish area. Look at what Widmer tried to do with the Alan Root Ford heads, it's all an attempt to make the burn happen faster. I don't think in today's world with canted valve heads producing the power they do, that you will be able to make up for the combustion advantage with the possibility of increased airflow, especially when most of that airflow "increase" is straight through and out the exhaust. It's not like the top level BBC or Ford heads flow like crap either.

Just my $.02

SWB

[Ron E]

The 426 style, yep, it's dated. The chamber is too big for hi static CR. No hi-end carbed big block is going to built on a 4.8" bore center in this age. The shorter block length (and shorter crank) tall deck,etc make it a natural for where it is: Fuel racing. Now it's mandated, but there had never been any sustained success at beating it, and nothing was on the horizon when the rules came into play. Everyone had 35 years to kick it's ass in T/F. Like SBC's and other engines that have stood the test of time, the hemi deserves it's chapter in the hall of fame.
I agree, it probably wouldn't take long for the SS/AH cars to be over run by technology. But, it ain't about that. At Indy, nobody is in the stands for SS/AM class run offs. They're way faster, but nobody cares. SS/AH has the same appeal as pro stock. The rules are simple, there can be no factoring advantage.
Like pro stock, it's a pure class, where if you win and pass post teardown, there is nothing left to do but try to pick up the pace. While in all the other S/S and Stock classes, if brand A won, brand B and C are bitching about the HP factor, etc, etc. In comp, they're mad about the index.
But on hemis and wedges and canted valve motors, NASCAR and NHRA P/S engines are slowly doing it, while the IHRA P/S engines have already done it. Thats given a long standing set of rules, physics will lead all brands to the same place eventually. So, for any given set of stable rules, we'll see some type of engine rise to the top. And, the rules ultimately pick the engine

[J.C.]

believe Peugeot invented the hemi combustion chamber way back, then the hemi design chamber was used in WWII warplanes. so, the Mopar boys have the French to thank.

[Gary Blair]

My thoughts are that the original Hemispherical design is best suited for a supercharged application. It really shines in this arena.

The twisted or rotated Ford design does better in N/A applications. The new gen B-441 owned IHRA Pro Stock until the Chevy builders copied it.
It's a north south valve layout but the valves are canted so they will not touch on overlap. 700 CFM @ 1.300 is not uncommon.

Rotated wedge designs that look like Hemi's seems to be where everyone is going. Take the original Boss Ford and flatten the valve angles to something like 9° X 7° on the intake and 3.5° X 3.5° on the exhaust but in the same opposed layout and you have basically a shallow twisted Hemi. Isn't the DRCE III pretty much like this?

Those of you who are going to the PRI take a look at the new Ford Hemi/Wedge renwood on display by Eliminator.

[Gary Blair]

believe Peugeot invented the hemi combustion chamber way back, then the hemi design chamber was used in WWII warplanes. so, the Mopar boys have the French to thank.

Some think that Duntov was instrumental in influencing Chrysler to develop a Hemi engine. Duntov designed the ARDUN flathead Hemi conversion heads in the 40's. Being of Soviet desent he was probably influenced by European designs.

A Google search will show an article that credits Peugeot, but I seem to remember it was a female engineer that designed the Hemi chamber in 1904. I can't find a reference though.

[Robert Kane]

I have to agree with Ron. The SS/AH classis what Super stock is all about. It is a shame there aren't enough 427 T-bolts around and ZL-1's to make things more of a "brand" rivalry. Lets face it these guys are all about bragging rights. Hemi Challenge. You don't see a 327/350 challenge. I was freezing my butt off at the Dutch Classic this year to watch 30 Hemi cars battling for top honors. It was incredible!! It was announced that Bucky Hess had spent over $100K in development to make his Barracuda run those low 8.50's at 155+ mph! Simply awesome with a 40+ year old design. I for one love the hemis and their big speeds and huge drawn out wheelstands, I can remember seeing John Friel's Dart carrying the front to the 330ft cones like it was effortless! I too bleed Chevy orange, but those Elephants give me chills every time!
Does anybody have the straight scoop on exactly why NHRA combined both into AH? Was it the linited number of stick cars vs. the autos?

The only thing I don't like about watching the SS/AH cars is sitting through 150 S/C dragsters to run first! zzzzzzzzzz!

Robert.

[Gary Blair]

I have to agree on the show and entertainment factor. I bleed blue but I like to watch the Hemi show as well.

There will be two SS/A Thunderbolts out there in 07. They are light and should be able to run .60's in good air. The 428 Cobra roadster is also legal for SS/A but I haven't heard of any being built.

[larrycoyle]

Talking about Bucky Hess spending all of that money is nothing new when it comes to those cars. Does anyone remember when a guy named Tommy Slaughter had one of those SS/AA beasts years ago? I think S.E. Buchanan drove the car. Even back then Tommy mentioned to me about the buckets of money he spent on that car and that was back when. All of this just goes to show the sanity of a true drag racer.

Any of you older folk remember or ever work on a set of the old Ford Tunnel Port heads? Talk about a different design and controversial...

[Windsor377]

I remember them but never work on a set. Ford even had a set of tunnel ports cast up for the Windsor back in the early 90s. Interesting to look at, but best left in the past I think.

[Gary Blair]

Talking about Bucky Hess spending all of that money is nothing new when it comes to those cars. Does anyone remember when a guy named Tommy Slaughter had one of those SS/AA beasts years ago? I think S.E. Buchanan drove the car. Even back then Tommy mentioned to me about the buckets of money he spent on that car and that was back when. All of this just goes to show the sanity of a true drag racer.

Any of you older folk remember or ever work on a set of the old Ford Tunnel Port heads? Talk about a different design and controversial...

The 302 Tunnel Ports didn't do well in Trans Am in 68. The Boss 302 was much better in 69 and 70. The 427 Tunnel Port did well in NASCAR winning the 67 & 68 championships. The Junior Johnson 351 Tunnel Port from the late 90's didn't do as well as the Yates. It had a EIIEEIIE valve layout with a Cleveland valve cover.

[Windsor377]

Gary did you ever take a close look at the 302 tunnel port? If I remember correctly, I though the port was kind of on the small side for all the brew haha.

...then they went waaay the other way with the Boss 302 head, which seemed to take some design cues from the Weslake. Don't give me a quiz on the Weslake, I'm just going off of what I recall...lot of dust in there...