| Author | Message | ||
     Natexlh1000 |
I don't see what the big deal is with hemi heads. My ironhead sportster has hemi heads from the factory.   | ||
| Buelliedan |
All 2003 and older 1200 Sportsers (except S models) came with Hemi chambered heads. So did S2s. But none of those are exactly hp kings! The hemi chamber is not a good thing. We can make just as good of flow numbers using XB heads and some stage 3 headwork as those $3,000 heads are producing. So lets see, $1,100 for stage 3 headwork or $3,000 for new heads. You decide. | ||
| Natexlh1000 |
$3000 - $1100 = more beer money | ||
| Rick_a |
Typically a hemi chamber is good for flow but not so good for combustion efficiency. The angled squish band is meant to be a compromise between flow characteristics and effective squish area. Some argue that squish is unnecessary if you have effective swirl characteristics. The hemi was king in the 60's, and today is a good marketing handle for Dodge. | ||
| Xl1200r |
The hemi was king in the 60's What's interesting is that both Ford and GM produced engines of nearly identical displacement (within one cubic inch) that made similar, and sometimes BETTER power. Hemi is a load of crap. The XB heads, from everything I have read, are the best heads out there for Evo XL-based engines, and only get better when breathed on. | ||
| Buelliedan |
XB heads are the best factory heads ever made by HD. They have taken the design of those heads and now applied them to the Twin cams and Sportster heads also. I always have wondered if somebody at Buell actually designed the XB heads or was it an HD engineer? | ||
| Court |
>>>>I always have wondered if somebody at Buell actually designed the XB heads or was it an HD engineer? How about if it was a HD engineer working at Buell? There were a number of folks involved, a true collaboration. Aside from the instant "who done it?" it's safe to say that had it not been for Buell HD would never have had them. They were counting on this on February 3rd. | ||
| Bad_karma |
I'm of the belief that Hemi heads allowed for large valves for a given cylinder bore over a wedge. But the problem I have with Hemi heads is the dome on the piston. That is excess moving mass. Joe | ||
| Ducxl |
Excessive domes promote poor flame propagation.Not a good thing. | ||
| Rocketman |
It's all a trade off no matter which piston / combustion chamber shape. End of the day there are many deciding factors entering into the equation, but I'm not familiar with a good 'hemi' type head that works bad. Nor am I familiar with a good flat top piston or good 'bathtub' head that works bad. When something doesn't work well at all, it gets sidestepped for something that works better. I've yet to ever hear of one design of head / chamber / piston that works best of all, and none of us ever will. It's a constantly changing variable. I think one thing has happened since we've reached a more computer aided technological age in engine tuning. We seem quick to forget some stuff is still a black art, and that is something only some are good at getting the best out of, no matter how many computer aided programs are factored into a design. I'd rather have a seasoned pro tuning my heads than some freshman who knows how to use a flow bench. More to the point, a seasoned pro should be able to explain which shape works best for which application. That's something a computer can't really ever tell you, and that's why for me I'd rather follow the path of the black artist than that of the computer programmer with a Winpep degree. But hey, what do I know. Rocket | ||
| Glitch |
But hey, Wes and Pammy | ||
| M2nc |
What's interesting is that both Ford and GM produced engines of nearly identical displacement (within one cubic inch) that made similar, and sometimes BETTER power. Man don't fool yourself. The Hemi of the 60s was and still is king in NASCAR and NHRA. It's still King of NHRA since all Top Fuel and Funny Cars (no matter the body) use basic 1960s Chrysler design still today and they are still outlawed for the lower classes. NASCAR put a weight penalty on car with Hemi engines in the 70s to let other cars keep up. Remember Richard Petty's 27 wins (out of 48) in one season. Today is the best head design for a motorcycle push rod engine a hemi? I do not know but could have sworn someone thought so recently. | ||
| Rocketman |
True Glitch, but my comments above are mine and mine only and are meant purely as an observation of mine, no one else's. I could be wrong, and might very well be, though I doubt it, lol!! Now how about those old side vale hot rods..... Rocket | ||
| Glitch |
I wasn't saying you didn't know what you were talking about at all. I guess it was a little tongue in cheek humor. I know y'all are good friends, and I know Wes knows what he's doing with regards to the Black Magic that be head work. I just put the two together. | ||
| Ducxl |
It would've been very interesting to se,if Chrysler had continued the development in 1965 of the legendary DOHC 426 hemi.They say it had a 7000 redline and over 700hp in stock form.Too bad. I like the version of OVERSQUARE/4 VALVE engines that spin high and make HP versus torque.Though they say the longer duration of cylinder filling of an UNDERSQUARE/2VALVE engine is nearly equally efficient in cylinder filling? | ||
| Scott_in_nh |
Hemi is a load of crap. While I'll agree that Ford and GM made street engines with similar or more power, neither of their designs are used as a basis for 8000 HP top fuel or funny car motors.... And of course Ford was working on a overhead cam Hemi engine when the design was outlawed by NASCAR. I guess NASCAR recognized it was crap and wanted to save Ford from spending all that developement $$ right? Then there is the fact that Hemi equipped Dodge Darts still hold the record for I think it is AA Super Stock drag racing. This was a car that was a factory built race car (ALL the factories had them), kind of like the XBRR but more sucessful! So no, Hemi isn't the only way to go fast, but crap it is not.... (Message edited by scott_in_nh on October 27, 2007) | ||
| M2nc |
Then there is the fact that Hemi equipped Dodge Darts still hold the record for I think it is AA Super Stock drag racing. Those cars are cool. I believe the standing record for those are very low nine-second quarter mile times. That means that back in the late sixties you could buy a car from the factory that is still faster than the ZX-14 which is currently the fastest 1/4 miler motorcycle. | ||
| Rocketman |
No Glitch, I got the humour and what you were saying. I just didn't want anyone else drawing the wrong conclusions after BOTH our comments. Otherwise the Brown's would roast me! Thank you darling  Rocket | ||
| Djkaplan |
"That means that back in the late sixties you could buy a car from the factory that is still faster than the ZX-14 which is currently the fastest 1/4 miler motorcycle." No, actually, not right off the showroom floor like a ZX-14 with the right rider can do. | ||
| Scott_in_nh |
True, you needed to know somebody or be a well established team to get one. I believe they made something like 50 Darts and 50 Barracudas...That's why I compared it to the XBRR in scope. If I remember correctly they went to Hurst for the Hemi and lightening process (van seat, lightweight glass, straps to pull the windows up, no carpeting/radio/heat, fiberglass front fenders and hood, etc...). They also had a door tag that stated they were not street legal/race only but that didn't really stop some people from putting plates on them... | ||
| Glitch |
 Rocket | ||
| Buellbo |
One concept that I think is very interesting regarding the 4 valve head is the use of a primary and secondary intake valve. Honda and Yamaha have used this on off road and dual purpose single cylinder bikes, and Chevrolet used it on the ZR1 Corvette. | ||
| Diablobrian |
The old drag only specials were sometimes acid dipped to thin down the metal of the main body of the car too, so even the parts that couldn't be swapped out were lighter. There were a lot of crazy one-ups-manship stunts going on back then... | ||
| Skntpig |
Funny I just got this email after reading this post. Sorry so long... One top fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500. Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced. A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster's supercharger. With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. Cylinders run on the verge of hydraulic lock at full throttle. At the stoichiometric (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture of nitro methane, the flame front temperature measures 7,050 deg F. Nitro methane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases. Dual magnetos supply 44 amps to each spark plug. This is essentially the output of an arc welder in each cylinder. Spark plug electrodes are totally consumed during a pass. After halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 deg F. The engine can only be shut down by cutting the fuel flow. If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half. In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate an average of over 4G's. In order to reach 200 mph (well before half-track), the launch acceleration approaches 8G's. Dragsters reach over 300 miles per hour before you have completed reading this sentence. Top fuel engines turn approximately 540 revolutions from light to light! Including the burnout, the engine must only survive 900 revolutions under load. The redline is actually quite high at 9,500 rpm. Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimate $1,000.00 per second. The (NOT) current top fuel dragster elapsed time record is 4.441 seconds for the quarter mile (10/05/03, Tony Schumacher). The top speed record is 333.00 mph (533 km/h) as measured over the last 66' of the run (09/28/03 Doug Kalitta). You are driving the average $140,000 Lingenfelter "twin-turbo" powered Corvette Z06. Over a mile up the road, a top fuel dragster is staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The "tree" goes green for both of you at that moment. The draster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums and within 3 seconds, the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him. Think about it; from a standing start, the dragster had spotted you 200 mph and not only caught you, but nearly blasted you off the road when he passed you within a mere 1,320 foot long race course. That folks is acceleration... | ||
| Rocketman |
That's incredible! With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. That near-solid form I'd like to see with my own eyes. Rocket | ||
| Diablobrian |
I wonder just how much pressure they are pushing out of the superchargers, it would take an awful lot of pressure to render the alcohol/nitro-methane mix solid. | ||
| M2nc |
It is very impressive to watch and feel a top fuel dragster in action. When these top fuel dragsters go by you can see the air distortion coming toward you like a wave. Then when that wave hits you, you feel the detonations in the motor over your whole body. We have a video of the Swap Rat 30 making an exhibition run during the Mopar Nationals. In the video you see the wave then as the dragster passes the picture shakes like looking in a rear view mirror of a Buell. It is very impressive. | ||
| Rocketman |
I've stood track side at Santa Pod many a time and experienced just that. Sammy Miller's legendary runs in the rocket powered Vanishing Point at the Pod were similarly spectacular. Speeds of around 400mph in the quarter and virtual silence until that thing blew past you, and you really felt the shock wave. Rocket | ||
| Rocketman |
Here ya go. I was at them all! Slammin Sammy at the Pod By way of a reality check, I was at the Pod the day Alan 'Bootsy' Herridge was killed. Bootsy was trying something pretty spectacular back then. On the Saturday he'd completed several fairly quick shakedown runs in his Jet powered funny car. This car was different from previous jet cars where you sat in front of the jet. This one had the driver sat to the right side of the jet, and the whole package was the more normal wheelbase of top fuel funny cars. On the Sunday they ran the car for the first time with the funny car body on it. I don't know what caused the crash to this day, but to see the body of that car maybe one hundred feet in the air and a mushroom cloud at the end of the quarter mile was heartbreaking. Bootsy had hit the side rail really hard at such high speed he didn't really have a chance. That was a very sad day. Hard to believe neither he nor Slammin Sammy are no longer with us. Both were pioneers of drag racing in their own way. Rocket | ||
| Pammy |
Sknt, thanks for sharing that. I thought that post was great. It was almost emotional. It reminds me of Elmer Trett(bless his soul). The power of a Top Fuel Dragster. (The bike and the man) Rocket, Glitch, you guys are alright in my book...Now I have ta go see what the magician is up to today...  |
