Posted: 5/31/2005 3:04:57 AM EDT
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Anyone own one? I'm considering taking the plunge. Locking diffs, 4.56 axle ratio, 12,000-lb Warn winch. 5.7-liter HEMI® V8 @345 horsepower and 375 lb-. ft of torque, super rugged axles etc. Dodges attempt at a Rubicon.....gonna have payments forever, but what the hell, it'll be fun. ETA: HOLY SHIT! A SUNROOF!  Does that make it better in the mud? 
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How is it not a real Hemi? Because you dont' have to adjust the valves once a week or tinker with two Carter AFB's and dual points? It's not an original 426 Hemi from back in the day, but it does qualify as Hemi since it has hemispherical combustion chambers (which is what the name means). That said, I wish they'd make it available with a diesel. If they did I'd buy one. |
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Just FYI most non-Chrysler engines that did have hemispherical comb. chambers weren't called Hemis. It's all marketing now... Ford should market their 4.6/5.4/6.8 modular engines as the modern Cammer Cobra Jet. Remember those? 1965 IIRC - the 427 Cammer. Basically it was a 427 SOHC (dual cam) V8 with hemispherical combustion chambers but discontinued because of very limited production. It never went into NASCAR because of that, and Ford lost its competitor to the Hemi engines. However, hemispherical chambers have their limitations... you MUST use displacement in order to up the horsepower. With non-hemi chambers, like on a Ford DOHC V8, you can use multiple valves at a smaller displacement to attain comparable horsepower. I.e. the Ford Boss 260: 5.4L DOHC (quad-cam) V8 makes 350 hp and 370 ft-lb normally aspirated, it has 2 intake valves and 2 exhaust valves per cylinder. That's 5.4L vs. the new Dodge 5.7L Hemi V8. This is more efficient. Chrysler is depending on Mercedes Benz's Multi Displacement System (MDS) for fuel economy on the Hemi equipped cars (Magnum RT, 300C) and the MDS compromises performance for fuel economy. The 300C SRT-8 doesn't use MDS and its gas mileage is horrible, but the performance is good. That's why the 2005 Ford Mustang GT has a 3V 4.6L V8 - it is a better compromise for fuel economy and performance. Even the 4.6L SOHC V8 4200lb Panthers made by Ford have better gas mileage than the 300Cs at the same horsepower levels (when modified). It's all about balance but Daimler is just doing a much better job in the marketing department. |
You think you know more than you do. Non-Chrysler engines with hemishperical combustion chambers were not called Hemi because Chrysler has the name trademarked. Same reason Burger King can't call any of their burgers a "Big Mac". The 427 SOHC died on the vine because it could not be made reliable enough for production street use (the timing chain being about 10 feet long would only last a very short time). NASCAR tried to keep Chrysler Hemis out of racing by passing a rule that to race a car it had to be sold to the public for street use. Chrysler had the balls to release the Hemi in street cars in 1966. Then NASCAR again tried to kill it by passing a rule that you had to sell a minimum of 500 to qualify. Chrysler complied. Then they raised the required number to 2000 for 1970 and again Chrysler complied. Finally NASCAR simply banned them. Most motorcycle engines made in Japan since the late 1960's have had hemisherical combustion chambers, as have MANY small cars starting with the early Dodge Colt's which were made by Mitsubishi. There have been VERY few engines made since the original 1950's Chrysler Hemi's that were "true" hemis since the shape of the piston top and the combustion chamber aren't perfectly hemispherical, including the 426 and Ford's 427. For that matter the Boss 429 (sometimes referred to as a "semi-hemi") was pretty much a hemi design. They just couldn't call it that. Your assesment that you "must use displacement to increase power" is pretty far off the mark too. Besides the fact that increased displacement always results in increased power (Hemi or not), what makes you think that you can't have 4 valve heads on a Hemi? Ever heard of a Honda (or Kawasaki or Yamaha or Suzuki)? Furthermore the REAL advantage of the Hemi design is the cross-flow layout of the valves, and especially the placement of the spark plug directly at the very top of the combustion chamber, which allows higher compression ratios (higher piston dome) with less interference with the flame front propagation (which is a big issue with domes pistons with the spark plug to the side of the chamber), meaning more complete combustion and less risk of pre-ignition and detonation. |
Waldo has one I think: Click Here |
IMO, the only no-brainer good thing a true hemispherically shaped combustion chamber inherently offers for a street engine is combustion effeciency. There are penalties that come with it however. A hemi's chamber is naturally very-very large which makes for a poor compression ratio with normal, lightweight, flat-top pistons. Hemi pistons have to be domed to get a decent ratio, which makes them heavy--top-heavy; it makes them noisy, and it makes the cylinders and pistons wear rapidly. (Ironically, what makes the hemi a big compromise on the street, makes it a killer when it's supercharged for racing, or if one doesn't mind rapid engine wear--like in a NASCAR type race.) The combustion chambers on the new hemi are "quenched," which means there's meat added to the combustion chambers so as to get a decent compression ratio without having to use heavy, domed pistons. This is what people cite when they say it isn't a "true" hemi...but it's a good thing, not a bad thing. Also, IMO, MDS is no more electonically complicated than variable valve timing technology, and certainly no more mechanically complicated than additional valves and their actuation gear. A large engine, with just two valves, doesn't need VVT to effeciently make enough power to propel a 70 mph car with the engine running at a mere 1500 rpm. Four-valve engines need VVT to produce power at low rpm, ironically because they flow so well (it's sort of a vacuum thing--what makes multi-valve engine do so well at high rpm makes them do poorly at low rpm, but VVT goes a long way to reduce the compromise impact at the expense of complication and long-term reliability.) For drag racing, give me a supercharged, "true" hemi with all the displacement I'm allowed. For super high performance on the street, give me a 4-valve V-8....with all the displacement I acn get. For an exciting grocery getter, give me the GM LS2 or DC Hemi V-8, please. |
Then stop calling them "Hemi's" if they aren't. It's a sham. |
| There's more to a Hemi than just the heads guys. One of the major reasons that the 426 Hemi is so successful is the block design. If you really study it, it is a "deep skirt" design with the main bearings recessed in the bottom of the block. This allows cross bolting. These design attributes give the engine and EXTREMELY strong bottom end. 8000 HP anyone? The new "Semi Hemi" has a similar block layout, giving it extra strength. In fact these new Hemi's are detuned to keep reliability and mileage way up so there can be a decent powertrain warranty. Have you ever seen the warranties on the original Hemi cars? The new Hemi has an enourmous amount of power potential. In fact Hotrod magazine did an in depth study, and found that it has more potential than any other modern engine design. The true miracle of all this is that it cost's DC less to manufacture than the old LA series small block V8's that it replaced, with better fuel mileage to boot. It's NOT a poser. It WILL live up the the hype, weather you want to call it a Hemi or Semi Hemi doesn't matter. It's here to stay, and It's gonna get bigger and more powerful in short time. I guarantee it. |
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The new Hemis are slow - the 300C/Magnum RT in stock form were running inconsistent 1/4 times. Most were in the mid to high 14s... newsflash: The Ford Panthers with the same hp and same weight are running high 13s. The reason: The Mercedes MDS is restricting the potential of the "Hemi" 5.7 V8, and that is why the 300C SRT-8 does NOT have the MDS and is getting horrible gas mileage figures. Yes the Hemi will be/is a big thing and will stay as long as gas prices allow. But it's still a Chrysler and Big 3 quality do not belong in the same sentence. I don't know a lot about the history of the old Hemis, but I do a fair amount of research on modern engines made by other competitors. Hemispherical combustion chambers are obsolete and not the wave of the future. Thanks to DCX marketing hype, they're selling like hot cakes. Ford is focused on a compromise of fuel efficiency and power. With a hemi chamber, you cannot have a 4V setup. With a 5.4L V8 that Ford has, you're limited by RPM due ot the length of the connecting rods. However if you allow for more air flow at the limited RPM range, you can boost torque production. Let's look at the figures shall we: Chrysler 5.7 "Hemi": 345 hp and 375 ft-lb Ford 5.4 Quad-cam Boss 260: 350 hp and 370 ft-lb I'd say they are about even for horsepower and torque. Ford did it with 0.3L less displacement.  The only problem is that Ford has its head stuck so far in the sand that theyre not using this engine (tried and true in Australia) on the American cars. The 2005 Mustang GT has a 4.6L dual-cam 3V V8 making something like 300 hp. They run 13.4-13.6 in stock form. I'm not saying the new Hemis are crap. I am saying that their success is due to marketing hype. "Does it have a Hemi" "Dude, it's got a Hemi" etc... are now catch-phrases among the gearheads. Ford engines aren't even really known other than the fact its "a Mustang engine" The Ford modular engines are OHC V8s, similar to what Ford used in the 60s with its 427 Cammer except with lots of differences... if that makes any sense. Ford should market the "new" (since 1991) modular engines as Cammer Cobra Jets or something. If you want to know something else: The Aussies have a Ford 4.0L DOHC I6 that is turbine supercharged to produce 321 hp and 331 ft-lb of torque. Forced induction can somewhat be substituted for displacement and I saw pics of a blown 300C SRT-8 (centrifugal blower). I'd estimate at least 550 hp depending on amount of boost. |
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"The new Hemis are slow - the 300C/Magnum RT in stock form were running inconsistent 1/4 times. Most were in the mid to high 14s... newsflash: The Ford Panthers with the same hp and same weight are running high 13s." Your numbers don't add up. The curb weight of the Pantera was around 3100 Lbs. The curb weight of a 300C is around 4000 Lbs. All test results I've seen for the 300C put it at an average of 13.4 seconds in the 1/4 mile. The 300C is faster on any day. look it up. Newsflash: The Pantera was a POS, constantly plagued by recalls and TSB's, it was a maintenance/reliability nightmare. The 300C's reliability has been documented to be better than Mercedes Benz equivalent's. " Hemispherical combustion chambers are obsolete and not the wave of the future." There are many automotive engineers who disagree with you. I'll trust their judgement. "The Aussies have a Ford 4.0L DOHC I6 that is turbine supercharged to produce 321 hp and 331 ft-lb of torque." Have you ever heard of the Aussie Hemi straight six? It's the winningest engine in that country's history. It makes more power than that supercharged Ford and it was also designed by Chrysler. You seem to very slanted to Ford. Well good for you. Just don't let it get in the way of the FACTS. |
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