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Re: HEMI Quench?
[Re: Cab_Burge]
#815936
09/28/10 10:14 PM
09/28/10 10:14 PM
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Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
torkrules
I'm neurotic
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I'm neurotic
Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
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Quote:
We don't call them Hemiroids for nothin   Now, if we had a double overhead cam hemi in production that could possibly resolve this debate  NOT  I was suprised several years ago when I built my first pump gas low compression street stroker motor that ended up making 1.37 HP per C.I. with a set of ported 906 iron heads. I was building and dyno testing a lot of motors then and I had not had a pump gas 426 Hemi make as much HP or torque per C.I. as that low deck wedge stroker did  Still haven't That 512 low deck motor had absolutely no quench, 22 CC dished pistons .025 in the hole with a .042 thick head gasket and I used a stock low deck Edelbrock six pak intake and factory vacume carbs. I guess my message is anyone can make power with a wedge, not all of us can do the same with a 426 Hemiroid  Maybe Ma Mopar saw the writing on the wall( 426 Hemis don't work as good as the L.A SB do HP per C.I.)) and decided to quit making them(426 hemis) and blame it on the govement emission rules and insurance companys  
FWIW my first go around with one of these things did bring a few things to light. Previously I has a 496 wedge with a .650 lift 290 duration roller cam, 1050 carb and eddy heads that flowed around 310, and had 11.2 comp. that engine made 630HP/650lb.ft of torque. It was all done at 5800 and made max torque at 4000rpm.
The Hemi is a 472, K8 Hyd cam, MP single 4 intake, 9.5 comp, and intakes that flowed around 320 (this was the first go around). It made 6000Hp at 5800/585lb ft of torque at 3500. It seemed to me it was a lot easier to get the performance out of the Hemi without going too radical and it did it's best at 33 degrees timing as opposed to 35 for the wedge.
I have found that it's not totally immune to pingging. There are other factors here that make this combo different (heavier car, less gear, 4 speed) but you still need to keep this in mind.
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Re: HEMI Quench?
[Re: 52savoy]
#815939
09/29/10 08:53 AM
09/29/10 08:53 AM
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Joined: Apr 2007
Posts: 2,027
Trumbull,CT.
jim sciortino
top fuel
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top fuel
Joined: Apr 2007
Posts: 2,027
Trumbull,CT.
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Funny how people overlook the flaws on the Chevy head and the millions spent on R&D to correct them over the last 4+ decades.
Do max effort "chevy" heads retain their sloppy chambers, or weak rockertrain, or lousy ports (among other things)...........I think not. If it comes down to FACTORY iron, I'll take a HEMI over a 427.
We all see how the development of the "99" prostock head does in the power making department. Is it radically different than a stock HEMI??? Of course......but so are the chevy heads compared to a stock iron rec. port head.
ALL factory performance heads had strong points and drawbacks, it's the aftermarket that has been kind to the chevy and ford deals for economic reasons that has led to their capabilities. As was mentioned in a pervious post, lets go back in time to 1970 parts and see how the chevys and fords would do without their non-stop, aftermarket development against the HEMI.
If I recall, they did't fare to well before the heavy hands of NASCAR and the NHRA put the HEMI to bed.
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Re: HEMI Quench?
[Re: Monte_Smith]
#815941
09/29/10 10:15 AM
09/29/10 10:15 AM
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Joined: Aug 2004
Posts: 2,128
sweden
sshemi
top fuel
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top fuel
Joined: Aug 2004
Posts: 2,128
sweden
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Quote:
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I need to fill in with what i always say to my friends complaining about the old american iron motors.... you dont see any chevys/japs run in top fuel. 
What works for a blown fuel combo, has absolutely ZERO bearing, on what translates to real world motors. Blown motors, are terribly inefficient, heavy pack mules. There is nothing trick about them, nor will ANY single part of it, transfer to a stock HEMI. They have two things going for them, they are extremely durable and required by the rules. A blown motor is simple, massive ports, massive fuel and push as much of each through it as you can. All of that has no bearing on a N/A motor.
Monte
whooh... that was just a joke.
I dont think you need to be super smart to understand that Chryslers 426 hemi motor design is NOT the best out there.
If it was every motor in performance cars would have a similar design.
And i agree a sb makes much more tq/cui than a hemi.
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Re: HEMI Quench?
[Re: B G Racing]
#815943
09/29/10 01:48 PM
09/29/10 01:48 PM
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Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
torkrules
I'm neurotic
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I'm neurotic
Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
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Quote:
Not looking to get into a big debate but the hemi design was the greatest thing that happened to engine cylinder head development in centurys.That the demise of the hemi came at the hands of NHRA and NASCAR and no further development followed made the hemi design obsolete other than the feeble attempts of Ford and GM's alternate designs.With the advent of foriegn auto manufactures using the design in some semblance of the original configuration making some of their engine very efficient hopefully some sort of R&D will get the interest stimulated again.The biggest drawback(in my opinion) is the rocker and pushrod design and always felt that the attempts to eliminate the issues(like Ford) with the daul overhead cams that if R&D would have advanced the Hemi would reign supreme in racing venues today.The strides of manufactures to improve wedge and canted valve style heads has give them a slight edge over the obsolete under developed hemi heads as we know it.With the cost of such development and todays economy,I don't see anyone willing to spend the money for improving the hemi design for only a limited market. 
I remember reading something that Tom Hoover said years ago. The mentality wasn't to improve things it was to maximize profits. If you needed more power you made it bigger. You can see some mind set change in the 3G Hemi. Still not there yet, but you can see the improvement being made in the right direction. Had the 2G survived, who knows where it might be if they had spend the time and dollars to improve the initial design.
In my opinion it was always a compromise (they were sticking Hemi heads on a wedge block after all for expediency). What would have been produced had the whole thing been done from scratch? Who knows.
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Re: HEMI Quench?
[Re: Big Squeeze]
#815944
10/01/10 02:15 PM
10/01/10 02:15 PM
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Joined: Jan 2008
Posts: 4,255
Canada
WO23Coronet
OP
master
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OP
master
Joined: Jan 2008
Posts: 4,255
Canada
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BigSqueeze, what is the problem with the valve angles specifically? Do they cause shrouding? Reversion? With all respect, not trying to argue, just honestly trying to learn. As far as HEMI heads for a chevy, they do have them, but I beleive its for 5" bore spacing IHRA mountain motors. I think Sonny sells them. I don't think they sell HEMI heads for the street level guys for the same reason alot of people on this board slag the Predator heads, it's to far from what the factory offered and would get hounded by other brands to no end, which is I guess the same reason no one offers an improved HEMI head for Gen 2's similar to the Gen 3 HEMI'S (personally, I see no problem with the Predators, dodge did the canted valve thing long before chevy or ford with the poly engines).
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Re: HEMI Quench?
[Re: WO23Coronet]
#815945
10/01/10 02:34 PM
10/01/10 02:34 PM
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Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
Hemi Allstate
master
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master
Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
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As far as HEMI heads for a chevy, they do have them, but I beleive its for 5" bore spacing IHRA mountain motors.
Didn't Arias make Chevy Hemi heads 20+ years ago?
1996 Ram 1500 Sport
1968 road runner
1952 Sears Allstate licensed, pump gas, Hemi 5.98 @ 115.73 1.33 60 ft. The best is yet to come. Painless Performance / Street RODDER magazine Top 100 for 2019
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Re: HEMI Quench?
[Re: jim sciortino]
#815947
10/01/10 09:59 PM
10/01/10 09:59 PM
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Joined: Dec 2005
Posts: 4,238
State of retirement
52savoy
master
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master
Joined: Dec 2005
Posts: 4,238
State of retirement
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Quote:
Funny how people overlook the flaws on the Chevy head and the millions spent on R&D to correct them over the last 4+ decades.
Do max effort "chevy" heads retain their sloppy chambers, or weak rockertrain, or lousy ports (among other things)...........I think not. If it comes down to FACTORY iron, I'll take a HEMI over a 427.
We all see how the development of the "99" prostock head does in the power making department. Is it radically different than a stock HEMI??? Of course......but so are the chevy heads compared to a stock iron rec. port head.
ALL factory performance heads had strong points and drawbacks, it's the aftermarket that has been kind to the chevy and ford deals for economic reasons that has led to their capabilities. As was mentioned in a pervious post, lets go back in time to 1970 parts and see how the chevys and fords would do without their non-stop, aftermarket development against the HEMI.
If I recall, they did't fare to well before the heavy hands of NASCAR and the NHRA put the HEMI to bed.
 another correct answer.... 
No one has mentioned that Chevy designed the "mystery motor" over several years and still it had a hard time outrunning a Hemi(10 years of NASCAR and NHRA sanctions made it possible). The Hemi was on the drawing board and won Daytona in less than a year(11 months?) from what I remember...
using a (modified)passenger car blocks and old 392 Hemi head technology. Not bad for a motor that was thrown together...
and now (almost)50 years later copies of them are making 7,000+ horsepower or 14 hp pci...how can that be considered inefficient 
http://en.wikipedia.org/wiki/Chevrolet_Big-Block_engine
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Re: HEMI Quench?
[Re: Monte_Smith]
#815949
10/10/10 01:16 AM
10/10/10 01:16 AM
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Joined: Oct 2006
Posts: 247
nc
moeflo
enthusiast
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enthusiast
Joined: Oct 2006
Posts: 247
nc
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Quote:
Quote:
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The disadvantage the Hemi has is NOT from quench.......it's from terrible valve angles (for a naturally aspirated application) and piston weight...........and the ONLY reason Hemi's do well in Super Stock is because they have two carbs, instead of one like the Chevy's..... 
Terrible valve angles... 
2 carbs
In the last few years NHRA has allowed '64 Hemi cars to run 1 carb in A/stock as long as it's a 1964 NASCAR intake. From what I'm seeing they run pretty darn good for antiques.
Your carb answer is a moot point since they never orginally made any single carb drag or street packages and can't be proven.
It's proven everyday, on race tracks everywhere. The SS/AH combo is a bad hombre, don't get me wrong, BUT, if you let a 427 Chevy weigh the same and get a sheetmetal intake, with two carbs, you might be singing another tune............I am as MOPAR as anybody, but I am also a realist and I know, just because it is a Mopar, does not automatically make it the fastest, or the most powerful. As Wayne said, the HEMI was king in its day, because of shear airflow, but the design itself is not the greatest. If it was, why is it, the wedge engines rule in N/A classes.............Call the NEW HEMI whatever you want, but it is basically a "twisted wedge" chamber and is NOT hemispherical at all.
Monte
Going to have to respectively disagree on a few points listed above.
1st. Nothing terrible about the valve angles in ANY application other than high static compression ratios. So, yea, they're terrible for max CR racing classes. Other than that, they're very good valve angles. They are the primary reason that 426 style heads have the best (not about the best) fuel dispersion of any head I've ever seen. Although overlap flow is universally thought to be why these heads are so nitro-friendly, I'm pretty sure the fuel dispersion is also a major factor. The reason the 426 type head is so good is actually pretty simple. 426's are shrouded straight long. The exhaust valve, at high lifts shrouds the intake flow. It's unshrouded on each side. The center of the short side is shrouded by the bore, but this helps control the expansion rate there. The bore on the short side actually helps flow. The result of the unshrouded sides is, enough extra side-flow to pull fuel out of the direction the port is pointed in. Any other type of head we've tested concentrates the fuel to some degree. A properly prepped 426 doesn't. The steep angles are the reason. Boss Fords are twisted, and lack shrouding toward the center of the chamber due to shallow valve angles. It is very noticeable when wet flow testing. Hemi 99's same deal. The small chambers and squish outweigh the wet flow advantages in high CR applications. But a nice long valve really high port casting with 426 valve angles would be great anywhere else.
2nd. Monte, if we use the "classic" chamber definitions, then you're right. A genIII hemi is not a hemi. But, using the same standards, a wedge is defined by being able to slice a chamber in half and have a deep end and a shallow end. A 6.1 isn't a wedge. With direct opposing valves, it ain;t twisted either. It would be a classic narrow valve angle hemi without the squish pads. So, I think it's a lot closer to a hemi than a wedge. With the straight-on ports and centered valve locations, it is not a wedge, as demonstrated by the just completer enginemasters competition.
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Re: HEMI Quench?
[Re: Dragula]
#815952
10/10/10 08:21 AM
10/10/10 08:21 AM
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Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
torkrules
I'm neurotic
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I'm neurotic
Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
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Quote:
Interesting discussion on Hemi valve angles. Seems pointless because the heads still follow the typically formula for 2 x max head flow = max Hp.....Does it really matter?
Holy polished Hemi Heads batman!
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Re: HEMI Quench?
[Re: torkrules]
#815953
10/10/10 12:08 PM
10/10/10 12:08 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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The deal is not that they make significantly more power per CFM but the fact that they out flow wedgies like you wouldn't beleive What wedge factory head can be easily made to flow 400+ CFM ? I have seen ported factory issued Hemi heads make 1000 HP, no 906 or even max wedge can even come close. To get 1000 hp wedge heads you have to look to the latest greatest and most highly developed heads out there not a factory head that was desighned almost 50 years ago.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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