Hemis and NHRA

[Maxwedge]

OK I want to know if they Run Hemis in NHRA, Because I have been told that and Have read it in variouse places as well as seen motor that look strangly like Hemis on TV.
I have seen a few torn down in the real world, and the ones on TV dont look like wedge motors to me.
I had read in car craft this last summer that supposidly ALL the NHRA cars ran direct derivatives of the Chrysler Hemi. They even showed pics of the heads. The only major difference Between the Stock head and the current ones were
NHRA head
Made of Billet Aluminum
The valves are a little Bigger
No water Jackets
the fuel is injected directly into they cylender as in Diesel Motors
But all important geometries are the same as the 426 mopar, like bolt pattern, cylender spacing, valve spacing. Valve angle etc etc etc.
So where they not talking about NHRA or is there a special class???I have also seen on NHRA today(the TV Show) where they talked about the 426 hemi derivative motors still dominating ALL the classes in NHRA? That was said by Big Daddy Don Garlets himself
what gives????????
I really just want to know
max

[This message has been edited by Maxwedge (edited February 09, 2000).]

[Larry S.]

Max Wedge, the nitro and alcohol funnycar and dragster classes are dominated by the hemi engine design. The prostock class, which is what the new hemi is being used in is a gas class and is basically dominated by Generic Motors engines, That's why all us Mopar fans want the new hemi to kick ass so badly!

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1970 392 Hemi Cuda

[Jamze Duncan]

maxwedge, as far as I know, (other than the Arias hemi) all the blown and injected hemi engines I've seen in NHRA & IHRA are derivitives. Not a single Mopar part in them. Not the block, the heads and certainly not the rotating assembly - nothing.



Yes, they are a 426 style hemi with the same headbolt pattern (though most run 5/8" studs), same 4.800" bore spacing - just not Mopar produced. Also, several style heads have smaller combustion chambers (than Mopar) and do not run factory valve angles (they've been "tilted" or "rolled") - and some heads, like a Stage-V (such as Amato runs) actually are a casting and can hold water. They may be "derived" from a 426 hemi, but again, likely don't have a single Mopar part in them.



Now my question is: Can it really be a "hemi" engine if it does not have a "hemispherical" combustion chamber?



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Hemiperson

[This message has been edited by Jamze Duncan (edited February 10, 2000).]

[Maxwedge]

The Arias and the stage V Heads are(from a few things I have read) copies of the old (1971, I think, racing heads)D-4 magna hemi heads.
with the exception of what they did to the exhaust port.
The only head that I have read about that really deviates from the mopar hemi is the Indy Head which canted the valves 2-5 deg(I cant remember exactly) because at overlap the valves wouldn't collied with the bigger cams or valves.
The valves arn't canted in relation to the bore center but rather turned on the valves base surfce(the side that would meet the piston if all went badly) axis.
That is to not say that other hemi heads arnt different from the mopar unit though.
Do you have any more specifics (oddities)on the other heads???
Maxwedge

[This message has been edited by Maxwedge (edited February 10, 2000).]

[Jamze Duncan]

Maxwedge, I have 3 differennt sets of hemi heads. (1 set Veney, 2 stage-V's) None of them have the same exact valve placement - nor the same valve angles - and certainly the intake or exhaust ports are not in the same identical position. These things have come so far from a D-4 that about the only thing you can say about them is - they're all hemi heads.



I believe the Arias hemi head (still available) was developed with a 4.840 bore centerline and patterned to bolt onto a rat chev block. Another oddity, (I believe it was Mickey Thompson) in the early 60's marketed a real "hemi head" that bolted onto a smallblock chevy! I believe it was in the early 50's, Zora Duntov designed the Ardunn hemi head that bolted onto a "flathead" ford. It certainly didn't look a flathea@Ýrd.



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Hemiperson

[This message has been edited by Jamze Duncan (edited February 10, 2000).

[Maxwedge]

Originally posted by Jamze Duncan:
Maxwedge, I have 3 differennt sets of hemi heads. (1 set Veney, 2 stage-V's) None of them have the same exact valve placement - nor the same valve angles - and certainly the intake or exhaust ports are not in the same identical position. These things have come so far from a D-4 that about the only thing you can say about them is - they're all hemi heads.

According to a 1995 artical in "Chrysler Engines Volume 1 from Chrysler Car Enthusiast magazine"
and I quote from page 68 paragraph 1
"Joe Schubeck (the owner of Lakewood) became interested in the Hemi design and purchased the D-6 design. This was supposed to be an aluminum version of the D-4 with twin plugs. It also featured the the rounded "D" shaped exhaust port that is slightly raised on the head.--when Schulbecks buisness intrest led in other directions the D-6 Stage II was then purchased by Eric Hanson of Stage V Engineering, in 1984. From then on the D-6 stage II became known as the Stage V Hemi Head"
as far as my information that the Arias heads were also derivatives..I must admit I dont know where I got that bit of knowledge from..I may have been hallucinating.
Maxwedge




[This message has been edited by Maxwedge (edited February 29, 2000).]

[blowncuda]

Don't forget the BAE(Brad Anderson Engineering) head which is what most fuel and alcohol guys run,There is also the Allen Johnson head that a few teams run also. As stated previously these things bare a resemblence to the stock piece but that is about it. There is also a block that alot of team run called the TFX block again similar in looks to the Chrysler piece. How bout the new Fontana Hemi piece..A Chevy no doubt!!!! What will they do next!!! BTW that new Pro Stock Hemi has no resemblence to the original hemi at all,the original Hemi design is not competitive in NHRA pro stock any longer something about cannot get compression ratios high enough with the old design thus the new one...Hope it works out.

[Maxwedge]

From an issue of car craft last summer, I read a review that they did on the Pro Alcohol Supercharged motors, and in it Car Craft said the only major difference between that motor and the stock 426 hemis were
Aluminum blocks
Billet aluminum heads
No Water Passages
and the intake and exhaust valves were a little bigger. Not much, but the geometry was all the same!
Are we talking the same class? or is Car Craft wrong in your opinion?
Max


[This message has been edited by Maxwedge (edited February 29, 2000).]

[blowncuda]

I have seen both BAE and the Allen Johnson head and neither has the same valve angle as the original Hemi engine. As for the valves they are enormous,I do not remember the exact size but the intake was around 2.50 and the exhaust was around 2.00. Not to mention the rocker stands and gear. Also the blocks have 6 bolt mains with billet caps. Similar to an original hemi but not that close. These were both on Federal Mogul Dragsters(the old top alcohol class). Looks like Camaro Craft strikes again..

[DartGT66]

I remeber crew chief Keith armstrong saying a couple of years ago that they used stock 426 Hemi intake rockers in their nitro engines; they acted like fuses, if something was wrong the intake rocker would break and not open the valve if the burn was still going on in the cylinder, that was a way to avoid blower explotions.

[Jamze Duncan]

Blowncuda,

Camaro Craft? Let's face it, (other than Super Stock) it would be very hard to take a hemi that was originally brought out in 1964 - and make a competitive piece out of it today. Besides the pure weight of that old cast iron block, it wasn't engineered to take today's cylinder pressures or horsepower. I'll take a "derivative" K-B or TFX over a factory cast iron block any day. As far as factory 426" hemi heads go, their flow isn't even in the ballpark with what others currently offer.

I would think that to take something that would not be competitive, and to improve it to where it is - should be applauded. I love hemi's, but I'm not a hemi "purest."

A 426 style hemi has a lot of inherent flaws in an unblown application. Very heavy pistons (compared to any wedge) if you want high compression, often too much cylinder charge goes out the exhaust port on valve overlap and etc., etc. All of these things have to be worked around on an unblown application. That's why Mopar decided they had to come up with an entirely different "hemi" head for Pro Stock. Now blown, that's a different story! Some of the same things that hurt a hemi's performance in an unblown state - are exactly what you want in a blown engine (super efficient exhaust flow & etc, etc.).

Camaro Craft? I guess if that's what you call hemi derivatives, so be it. The simple fact of the matter is, they are much better than anything the factory ever produced. I have a big cube Pro Mod nitrous "hemi" that has a factory rear main seal and starter - that's all the factory makes that I can use on it. When that green light comes on, it all boils down to the "survival of the fittest." And a derivative just happens to be a whole lot "fitter."

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Hemiperson

[blowncuda]

Jamze Duncan

I am not sure you read my post accurately or maybe I was unclear. The "Camaro Craft" is a shot at the magazine article that Maxwedge was reading...You know Car Craft...The Camaro Craft is a reference to their overwhelming tendancy toward Camaros in the past,although that seems to be changing a little.. It had nothing to do with the Hemi derivitives or the new pro stock engine. I am well aware of the downfalls of the old Hemi in Pro Stock type engines. The main problem is not being able to build enough compression in the old style engine to be competetive in pro stock with the GM and wedge guys..You cannot make 17 or 18-1 in the old hemi which is what it takes to build competitive Pro Stock engines today!!! Do not forget there are also Hemi derivitives that are based on the Chevy BB in the Fontana..That was designed for Blown Pro mod type applications..My bottom line would be as I said earlier the old hemi and the current T/F,AA/FC,FMD,FMFC engines are not very similar at all. The main similarity is in their appearance underneath they are intirely different engines!!

[Maxwedge]

Jamze I never said that I would try or even think of making a stock type 426 hemi win in prostock. From what I understand the stock block could only take 1500-2000hp and the stock crank was only good to 7krpm and 600-800hp.
Besides Metalurgy has changed significantly since the inception of the 426.
but i tend to believe the few things I have read and seen that indicate that modern alcohol supercharged engines are more similar to the old hemi than they are dissimilar.
Big daddy said it and a few magazine articals said it and the new Hemi book(just got it) by Chrysler sais the same...
I am sure there are differences, but I bet there are vastly more similarities of the chrysler race motor to the hemi than Gm's race motor to the 454.
Maxwedge

[DartGT66]

One thing is sure; a top fuel or TA engine has far more in common with the 426 Hemi than a GM Pro-Stock engine with any GM production engine ever built.

[Jamze Duncan]

Blowncuda, sorry if I mistook your post. I've re-read it and still only see it as addressing hemi heads and blocks. I thought that was what you were talking about? I don't care what kind of hemi it is, I love 'em.

I really hope the new (semi-hemi, hemi?) engine proves to be competitive piece. Nickens positively has his work cut out for him. I suspect it could take SEASONS to get it to the point that it is competitive - I certainly hope not... because they'll likely give up on it as a design before then...

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Hemiperson

[Jamze Duncan]

Maxwedge, I'm not nitpicking - well yes I am in a way. Because it's those little "nitpicking" changes and details that have kept the hemi competitive in the blown ranks. I'll also agree in theory that the hemi is closer to production than a pro stock chev is - however, the new hemi certainly isn't a road piece is it? The days of production pieces being used for upper class racing has long since passed. What are we going to do now, discuss how "close" a derivative is to the original piece it replaces?

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Hemiperson

[Maxwedge]

I do not actually own a hemi, or three (I am envious Jamze). But I know of a few guys who have taken a crankshaft from a drag team, and replaced there stock Hemi crankshaft with said piece. The race teams usually let the crankshafts go after every few races and they survive a long time in a motor that wont see much beyond 5k rpms. My point in this is there is enough geometric similarity between the Hemi and the Pro/alcohol/supercharged motors to allow an exchange of the crankshafts. Sure custom rods have to be purchased. And on the pro motor I am sure the piston is totally different than the stock piece, and the valve train is worlds better than the 1964 versions, but the head intake port layouts and major geometry is the same. This is reinforce by what i have read and heard, Dartgt66 even said one team uses the STOCK exhaust rocker. If this is true then the geomoetry would HAVE to be exactly the same.
While I am sure porting has taken place.
the engine block bore spacing is the same. Although I would dare say the oiling journals and passages have been changed considerably.
I can take one of those heads and bolt it to the 426 block. Now it doesn't have water jackets, and I'm sure custom push rods would be needed
The distributers, while radically different Im sure, still tilt towards the passenger side, just like they used to.
Hell the Keith Black blocks(say that 3 times, fast) have Chrysler part numbers.
The only real major change is fuel system delivery. That is the only element that is completely alien to the old production/race motors. The current fuel delivery system is more like diesel engine delivery than a production car. There probably is more than what I can see or have seen with my limited experience
I see most of the differences in the old motor and the current race motor being mostly manufacturing, assembly and metallurgy. It is because of metalurgy and the weight savings that such elements as the rods/valve train and to some smaller degree the piston head, is different than the original. Those changes weren't initiated because of some design flaw in the math. But mearly an issue with current tech and materials.
In my mind these are the reasons for the deviation between what Chrysler ran up to the early 70's and now.
Maxwedge


[This message has been edited by Maxwedge (edited March 10, 2000).]

[Jamze Duncan]

Maxwedge, I just read your post after I came in from the shop - where I have milling and grinding on a KB Stage-8 block for weeks. Getting any hemi block to accept a crank with enough stroke to get close to 700 cubes definately takes a lot of time and work. Regarding hemi heads... besides factory castings, there are a number of OTHER manufacturers out there. And no, they don't all use factory hemi valve angles and port angles. One good indicator, when you are looking at a complete hemi head, can be the rocker stands. If they are aluminum, there is also a distinct possibility the valve angles have also been changed. When this is done, the rockershaft must also be moved to center the rocker on the valve (this can also be due to changing rocker ratios).

Just because one team can use a stock exhaust rocker, doesn't mean other manufacturers don't utilize OTHER valve angles.



While we're just talking hemi's here.. A blown hemi's strengths & weaknesses are entirely different from a nitrous Pro Mod engine like mine. What I need for a nitrous engine is lots of cubes, much less emphasis on exhaust scavenging, LIGHT high compression pistons (which evidently NO ONE has a ultra-light blank to make one from) and intake runners that stand considerably more vertical than a standard hemi - and while I'm dreaming, how about 4.840" or 4.900" or (I'm foaming at the mouth here!) 5.00" bore spacing?!!.

The current hemi I'm building has the newly released Stage-V "Tilted" heads and as far as I can detect, a stock hemi valve train wouldn't even come close to working. If everything was the same as some keep insisting, why won't they? The answer is easy, they're simply not the same. By the way, the Stage-V heads DO have water and I see no reason why they wouldn't still bolt on a 1964 426" engine. But that doesn't make them the same indentical heads, does it?

You are right about the deriviative blocks, since they have the same bore spacing and the same main bearing diameters - they will take any hemi dimensional crank. Getting a good used billet crank from a race team is a good way to save some real buck$. Though, I don't believe I would be worried about limiting the rpm's to 5,000. I would be more concerned about how many horespower & how much torque the engine made that it was going in. If a (good) billet crank has been handling over 6,000 horsepower at over 8600 rpm and you are anticipating putting it in something making, say 800hp, whay would you feel it necessary to limit it to 5,000 rpm's? If it is a "good" billet crank, that baby ought to be good for 10,000rpm if you had the components to go with it. Here just like everywhere else, the keyword is "good."

By the way, I was somewhat encouraged by the new hemi's outing at Phoenix. I hope, I hope, I hope - it does prove to be a competive piece. If it does, I'd love to try a set of those heads on an 700"+ aluminum block - with a ton of nitrous!

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Hemiperson

[Maxwedge]

as far as the crank in the old block thing, the guys I know only put cranks in from motors that were 500 cubes. They didnt quite say what they did, but to hear them talk about it, it didnt seem to be that big of a deal..at least to them.
And the valve angle thing, i could be wrong on, there are just things I have read, and people I have talked to that say most of the geomery is the same. I dont have any personal experience with it(spending money on colledge not cars...yet).
You could well be corrrect!!
as far as the pro mod thing. I was under the impression that the main limiter with the Chrysler derivative motor was the lack of compression that the motor can naturally build(12.5:1). But that doesnt limit it in the supercharged class at all.
anyway
I would have also thought that the smaller bore would make it able to rev higher due to
the lighter piston???but that is probably an issue where you find the "sweet spot" between cubes and rpm and which is most important...
also I have read somewhere that the Indy Hemi
could build 14:1cr naturally asperated..and I think that motor is an chrysler derivative.
But on the matching set of heads I also know that they tilted the valves on the valve face centerline. So the head isnt "Pure" chrysler. That valve tilt made it so they could put much larger than stock valves in the head...
Its also interesting that you have a "tilted" Stage V hemi head. If its the pro engineering stage V the head, as designed by chrysler, was not tilted.
Why do you think it was tilted? to help straighten the intake path and or do you think it was more of an issue of what that tilt does for the combustion chamber??
anyway
Good luck on your motor Jamze
Maxwedge

[This message has been edited by Maxwedge (edited March 12, 2000).]

[DartGT66]

Well, about the valve train, I said only that Dale Armstrong told they were using stock intake rockers, nothing about the rest of the valvetrain. And you can build higher CR in a Hemi, just like you can in a wedge, but it needs awfully lot more of work to make everything match. and there is no such a thing as a light Hemi pistons, the surface area of the chamber and therefore the surface area of the piston top in high Cr application is huge, must be about the same as in a 6.00"-7.00" or even bigger bore wedge and therefore the pistons will never be lighter than it would be in such a big bore wedge. With big stroker cranks there really must be some grinding because the block extends well under the crank centerline; you have to start grinding the stock block even with a 4.15" stroke and one can just wonder what it takes to put in a 5" stroke crank.

[Jamze Duncan]

Dart GT,

You are right about the dome area of a hemi piston normally needing to have a large amount of cc's to fill a large hemispherical combustion chamber. But don't forget that the amount of stroke comes into play here. I have a set of hemi pistons that would likely amaze you - because they hardly have much of a dome at all, and still produce a true 12.3 compression ratio. How's that possible? A 5.300" stroke crank. As I'm sure you know, the longer the stroke and the bigger the bore, the less dome is needed to achieve a specific compression ratio. I don't know where it came from, but those who think it is hard to obtain compression with a hemi, are not correct. I've had them above 16:1 - but have also found that doesn't work very well with nitrous.

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Hemiperson

[DartGT66]

That's true, didn't think about that. When the displacement goes up, so does the combustion chamber size for a same CR and you can use less dome than with a smaller engine.

[Jamze Duncan]

Maxwedge, regarding valve "tilt" on the Hansen Stage-V hemi head, the valves were tilted to increase valve size, increase flow and to change the runner entry/exit angle.

Does it work? Flowbench flow figures show it to be the best flowing Chrysler hemi head I've ever heard of. This is the same Stage-V head Ray Barton is advertising that flows over 550 cfm @ 28in @ only .800" lift (on a 4.500" bore). This is a little over a 13% flow increase (that's a ton) over both the older Stage-V and the Veney billet heads I have been running. I'll should soon be able find out if the flow figures translate into true performance. Hmmm. Strange - there for just a moment, I thought I could detect the faint odor of a "Rat Roast!"



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Hemiperson

[Maxwedge]

What, if anything, are you doing to make sure that extra fuel burns, 13% is alot more.
are you running dual plugs, or just a BIG spark..
anyway good luck on the rat hunt
Maxwedge

[Jamze Duncan]

Maxwedge,

The 13% increase in flow is a lot. However, this basically just gets these hemi heads into the arena of flow where the NHRA GM style heads already are. If 500 cubic inches can handle that kind of flow, I'm sure almost 700 will have no problem.

As for dual plugs, I'm not running them because with three nitrous foggers, timing retard on each system could/would become a nightmare. I don't know how you would do it without two complete ignition systems operating at the same time - that would mean two systems having to retard at the same exact time and at exactly the same amount of retard. Also, that big old open hemi combustion chamber with more of a centrally located sparkplug promotes flame much better than a wedge.

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Hemiperson

[Maxwedge]

Jamze
Just thinking aloud here
has anyone done any work on a OHC Hemi. From what I have read, the OHC platform allows the motor to use less valve spring pressure when limited to the same rpm range as a pushrod motor. OHC engines are supposed to like "sustained" rpms better than a pushrod motors.
The hemi could go with a single OHC config due to the fact that the pistons only have 2 valves each.
This "might" simplify the valve train up top
If it does it might lessen the need for so much oil up top also.
Less spring pressure, less wear on the valve train and less heat built up.
Other than more spinning mass(2 cams instead of 1) and the added complexity of the valve gear. What other disadvantages do you see on this idea??
also
has anyone to your knowledge put a modern coil over each spark plug type ignition on a Hemi???or any old BB???
It would probably be just as much of a pain to tune as the dual plug set up.
speaking of spark plugs this brings up another debate. The convention is for hemi motors to "Aim" the gap on the plug toward the intake valve and on wedge motors to aim it down. But from some fairly knowledgeable people, I have been told the opposite…What do you suggest or do you use something like the Bosch+4 plugs on your hemi??
anyway
good luck man
Maxwedge

[DartGT66]

I think Ford had the cammer, which is a SOHC Hemi. Also many japanese and european engines use this configuration, remember the Mitsubishi 4 2.6 Hemi?

[Maxwedge]

The ford cammer was mediocer at best, thus it wasnt produced very long. The other motors while hemis werent put through the torture test that the Race Hemi motors are. I am curiouse if anyone has applied that "new" tech to a big motor?? I do also realize that Duesenburgs motors tended to be Dual Over head cam Hemi motors(5000lb car built in 1930 doing 90 in second, and still having 3rd yet to go is an amazing thing!!!)
anyway
Maxwedge

[Marc]

Has anyone tried the Cobalt 32 valve hemi heads?? What sort of advantages would it have aside from the obvious? What kind of price are they?

[Jamze Duncan]

Maxwedge,



I'm old enough to remember the SOHC ford cammers. Actually, they were a competitive engine. Connie Kalitta, Don Nicholson, Tommy Grove, Mickey Thompson & "Sneaky" Pete Robinson, just to name a few, ran them. At the time, I actually thought they were a little "stouter" than the Chrysler hemi. However, they were EXPENSIVE! And were never put in a passenger car. If my memory serves me correct, a 427" ford cammer engine "in the crate" was about $1200 more than you could buy a COMPLETE factory new Dodge or Plymouth WITH a 426" hemi - ready to go to the track and run 11's! Now that's what Mopar used to be, "real bang for your buck" performance. A front wheel drive V-6 just doesn't compare, does it? They (Mopar) could certainly do a lot more in the performance market - if they chose to. Unfortunately, year after year, they choose not to.



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Hemiperson

[This message has been edited by Jamze Duncan (edited March 29, 2000).]