| |||||||
 |
| | LinkBack | Thread Tools | Search this Thread | Display Modes |
|
#1
01-18-10, 07:19 AM
| ||||
| ||||
 A Guide to Vortec vs OE Small Block Chevy Heads Small block Chevy heads have been manufactured since 1955, and have been used in high performance applications as soon as the first one rolled off the assembly line. Fifty-five years of manufacturing have left us with an endless number of different cylinder heads for the SBC engines. General Motors estimated that through 2005, more than 90 million small block Chevys have been produced, which means that there have been at least that same number of SBC cylinder heads produced. Add in the amount of high performance heads that GM Performance Parts have sold over the counter and the number is astronomical.  Enthusiasts continue to search for the best combination for their applications, and despite the environmental regulations, it is clear that technology has advanced and GM’s cylinder heads have gotten even better with age. When the Vortec heads made their V-8 appearance in the late 90’s, it was inevitable that the question would be asked: how do old school cast heads compare to the newer Votec heads? We take a look back at the Vortec offerings and pack you full of info on the SBC OE head vs. Vortec debate! Read on!  Old School Gen I Cylinder Heads [adrt][/adrt] The GM small block was specifically designed as a compact sized engine to embrace the economical use of iron and to streamline the production process. Part of the design process that was carried through to the Gen III design in 1997 was to create lightweight rocker arms for higher rpm operation, wedge combustion chambers for a broader power band, and deliver 4.4 inch bore centers (from the center of one bore to the center of the next bore). The first small block with a 4 inch bore came in the ’62 Corvette 327, and it really opened eyes. Featuring the famous double hump marking on the ends of the heads, the #3782461 and #3782461X heads used 1.94/1.50 inch valves. These were commonly called “Fuelie” heads because they were released with mechanical Rochester fuel injection on the stock engines. The only difference between the two casting numbers was that the #3782461 featured 160cc intake port, 62cc exhaust port and the #3782461X had the larger 172cc intake port, 64cc exhaust port. The double hump heads continued to be a favorite with performance minded enthusiasts into the new millennium.  Stock GM cast iron cylinder head, vintage early 60's. High performance enthusiasts separated the stock Gen I heads into closed chamber and open chamber heads. By far, the closed chamber factory heads were favored over the open chamber for making power due to the poor burn characteristics and no swirl (quench) inside the combustion chamber of the open chamber heads. Furthermore, the cylinder heads that were capable of making decent power were all manufactured when lead was prevalent in fuel and the valve seats stayed lubricated. Unless you were using leaded racing gasoline, the valve seats needed to be replaced with hardened valve seat inserts. By the time a racer was done modifying the heads, there was substantial monetary resources invested in the cylinder heads and it was hard to justify the modifications unless you were running in a class that dictated hardened valve seats in a cast iron head.  Casting number location on the old school cast iron heads. Some of the More Popular Gen I Cast Iron GM Cylinder Heads [adrt][/adrt] #3767754 - Manufactured from 1959-1961 on 283 Cubic Inch engines. Called the "Power Pack" cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers. #3774692 - Manufactured from 1958-1964 on 283 Cubic Inch engines. Called the "Power Pack" cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers. #3795896 - Manufactured from 1963-1965 on 283 Cubic Inch engines. Called the "Power Pack" cylinder heads. 1.72˝ intake valves and 1.50˝ exhaust valves. 60cc Combustion Chambers. #3782461 - Manufactured from 1964-1966 on 327 Cubic Inch engines. 161/62 cc port volumes, 62cc combustion chamber. Identified by Double Camel hump symbol. #3782461X - Manufactured from 1960-1963 on 283 and 327 Cubic Inch engines. 172/64 cc port volumes, 62cc combustion chamber. Identified by Double Camel hump symbol. #3890462 - Manufactured from 1966-1967 on 302, 327, and 350 Cubic Inch engines. 64cc combustion chamber. Identified by Camel hump symbol. No accessory mounting holes. #3917291 - Manufactured from 1967-1968 on 302, 327, and 350 Cubic Inch engines. 64cc combustion chamber. Identified by Camel hump symbol. #3932441 - Manufactured from 1969-1970 on 350 Cubic Inch engines. 161-165cc intake port. 76cc combustion chamber. #3932441X - Manufactured from 1969-1970 on 350 and 400 Cubic Inch engines. 161/65cc ports. 80cc combustion chamber. 1.94" intake/1.5" exhaust valves. #333881 - Manufactured from 1974-1975 on 350 Cubic Inch engines. 76cc combustion chamber. 2.02" intake/1.6" Exhaust valves. #3991492 - Manufactured from 1970 on 350 Cubic Inch engines. Available on the LT1 engine and over the counter. 64cc combustion chamber. Either straight or angled plugs. Don McBride of McBride Performance Engine and Machining in Lake Elsinore, California, still prefers the old school cast heads because his shop specializes in building engines for circle track racing and desert racing. According to Don, "The old style heads were built with a lot of metal. You have room to manipulate and improve the flow on these heads. Of course we still have to build the engines according to the rules of the tracks that our customers are running at, and for the most part, the old style heads are what they are mandated to use by the rules. The newer style Vortec heads have a lot cleaner castings, however. In the 60's and '70's, the factory didn't pay much attention to how much metal was in each casting like they do today, so there is a lot more areas to clean up in the old style heads. Because of the extra metal, the old style heads seem to be less prone to heating problems, and circle track engines get pretty hot." In the 80's, GM Performance Parts came out with their famous Bowtie performance heads for the small block. GMPP introduced the Phase I Bowtie small block Chevy cylinder head in 1981 for racing applications. Subsequent variations such as Phase II and Phase VI were later released, as well as NASCAR approved SB2.2 series. The Phase II was the most popular for hot rodders and featured a 184cc intake port volume, and 64cc combustion chamber. These worked well into the mid 80's when after-market cylinder heads became the hot ticket.  Older casting identification marks and casting numbers chart. Enter the Vortec Heads Starting in 1996 on several GM Trucks and Vans, the L31 Vortec heads came on the scene. Not just a modification of existing heads, but complete redesign using the 1996 Caprice/Impala SS LT1 cast-iron head castings as a base. The biggest change GM made in the new design was revising the water jacket so the new Vortec heads could be used on conventionally cooled small blocks. The idea of using the 1996 LT1 cast iron head as a starting point for a new performance stock head came from the fact that it was the highest flowing LT head used by GM. The 1996 Caprice/Impala heads outflowed the Corvette Aluminum LT1 heads by as much as 20 cfm on the intake side. The cast iron Vortec head was in development six months longer than the aluminum head, and during that time, GM engineers tweaked the intake and exhaust ports for additional flow. The cast iron Vortec heads was one of the first to purposely integrate tumble instead of large swirl numbers in the design.  Vortec's "heart-shaped" combustion chamber. The newly redesigned Vortec cylinder heads were intended to replace the swirl-port Throttle Body Injection heads that were previously used on GM 350 trucks. What got the power merchants attention was the increase in horsepower from 200 to 255 solely based on the power generated by these heads. By the time you purchased a used double hump cylinder head and had it reworked, the cost was the same as buying a new Vortec head that produced more power. Circle track racers were tossing their double hump heads as fast as they could buy the new Vortec heads.  Location of the Vortec heads casting number. How Many Types of Vortec Heads are Offered?
The L31 Vortec comes in two different casting numbers, 10239906 (#906) or 12558062 (#062). Originally, the stock #906 casting head was available in two versions. One version had an Inconel exhaust seat with single angle valve grind and was available on 1 ton trucks. The other version was the traditional three angle valve grind. Other than that, the #906 is the same as the #062 head.  The Vortec head "saw tooth" casting marking. GM Performance Parts Bowtie Vortecs are offered in "small port" (#25534351), which has 185cc intake ports/65cc exhaust ports, or the "large port" (#25534445), which features 225cc intake ports/77cc exhaust ports. Both GM factory and GM Performance Parts Vortecs come with 1.94 intake/1.50 exhaust valves. According to the engineers at GM, “Stepping them up to 2.02 valves doesn’t help them any, so it’s not recommended. The port was designed to match the 1.94 valves. With the Vortec flow velocity, you need less spark advance to make power which is a clear indication of a more efficient burn.” [adrt][/adrt] Air-flow in the Vortec heads begin to decrease between .500" and .550" valve lift. Their true strength is low lift flow which gives more area under the total flow curve which is where valves spend most of their time during engine operation. Valves spend much more time at .400" lift and below, which is where the Vortec outperforms most other heads. Combine this with high velocity, lack of turbulence, and superior combustion chamber design, and this is where the Vortecs really stand out. Even the GM Fast Burn heads can't touch the Vortecs at low lift because their ports are too big which makes their air flow similar but with less swirl. There are a couple schools of thought on the cast iron Vortec heads vs. the old school GM cast iron heads. The "bolt on" crowd likes Vortec's advancements. Gaining 35-40 horses by simply bolting on a new set of heads is definitely a plus. The hardcore circle track racers that are subject to rules that mandate the use of stock cast iron Gen I heads view things a bit differently. We talked with Bobby Thomas at Bobby Thomas Motorsports who agreed, "Vortech heads are newer technology and make more horsepower out of the box and off of the manufacturing line, but they have less material to work with and are more prone to heat issues." How are Vortec Heads Different from Other GM Cast Iron Heads?
 Side by side comparison. Side by Side Comparison We talked with Bill Hendren at Hendren Racing Engines about the flow characteristics of the Vortec heads compared to the old style cast heads. Bill explained that they had performed a lot of testing early on with the 906 Vortec heads and were initially surprised at the flow numbers. According to Bill, "The Vortecs required less work to get them to flow better. We tested our 906 Vortec heads with the larger 2.02 intake valves and it flowed in the 530 to 540 horsepower range where the old style cast heads flow in the 480 horsepower range." Bill went on to explain that the Vortec heads were "limited on how much you could do with them though. We could only run the intake valves to 2.05" where they started to lose air flow. And you can't do much porting with them. If you get too wild with porting, you run into overheating and cracking issues."  *Bowtie Vortec Heads with 2.02” Intake, 1.60” Exhaust Valves, 185cc Intake Port. **062 Vortec Heads with 1.94” Intake, 1.60” Exhaust Valves, 165cc Intake Port. ***492 Straight Plug heads with 2.02 Intake, 1.60 Exhaust Valves, 159cc Intake Port. Flow numbers are reprinted from Brzezinski Racing Products, Inc. All of Brzezinski’s flow testing above was performed at 28” of water with a SuperFlow 600 flow bench and Flow Pro software from Audi Technology. Other Vortec Tips and Tricks
 The Vortec heads (top) lack the heat riser and center intake manifold bolts that the old style heads have. The Winner Based on our information gathering, discussions with GM Performance Parts and Engine builders, and our own experiences, we found the Vortec heads to be the real deal. They are very economical, easy to get your hands on, and out perform the old style heads. The Vortec heads reigned supreme in every category except the "amount of work hours to make them flow better" category where the old style heads still rule. Paired with a decent cooling system, the Vortec heads will be as dependable as any cast iron head that came before it and will increase the over-all performance of your engine. That makes Vortec a real winner in my book! Recommended Spark Plugs for Vortec Heads
GM Performance Parts Web: GM Performance Parts | High Performance Crate Engines & Engine Parts Brzezinski Racing Products, Inc. Phone: 262-246-8577 / 866-236-6300 Brzezinski Racing Products, Inc. #1 in Cylinder Heads since 1980 | Cylinder Heads | UnderCover Porting Bobby Thomas Motorsports Hesperia, CA McBride Performance Engine and Machining Phone: (951) 471-2016 Hendren Racing Engines 1310 US HWY 221 North Rutherfordton, NC 28139 Phone: 828-286-0780  |
|
#2
02-25-10, 06:55 PM
| |||
| |||
| You forgot to mention that there is so called good heads and not so good MEXICAN heads that have the small runners and poor flow numbers and are more prone to cracking then the 40+ year old stock heads. The worst part about the Vortec heads is that you cannot use pop up pistons with them. The cheapest way to make lot's of compression is to use high rise pistons. As long as tracks has rules that mandates flat top pistons, you will always have people that are willing to spend piles of money on that stock crap, trying to get a competitive edge. Why not change the rules to allow any compression as long as the heads are not below so many cc's. As long as people holds fast to antiquated rules because that is all they know - then the only thing you can do is dismiss them as being ignorant, because there is no competitive edge to be had - by using pop up pistons. Lighter components will spin faster and will take more rpm's then heavier components. I believe one reason why most tracks do not change their rules is because the people who race already invested money into what they have and are unwilling to spend more money when the rules change. Yet if left unchecked, they will cheat and use the parts anyways. The engine builders con these people into believing that they must use these parts to win a race. Just so that they can justify the high cost of buying on of their professionally built race engines. |
|
#3
02-25-10, 07:46 PM
| ||||
| ||||
| Rowdy. You are an engine builder, aren't you? You make money off people by building them engines and selling them the dream of making more power. Having people buy stock stuff and installing stock stuff hurts your business, doesn't it? Let's call it like it is. Everyone that makes a comment has some motivation for feeling the way they do. And I think we have found your motivation. |
|
#4
02-26-10, 06:16 AM
| |||
| |||
| Bobby, I have not built a engine in 8 years and the last engine I built was on the tailgate of the Avalanche and was installed with a come along off a branch of a maple tree in the backyard. I am a machinist. I take pieces of material and I make them look like what is in the picture. I can remember my dad coming home one day all mad at the world and when I asked why he was so bummed out, he said his boss yelled at him because he missed his cut by 3 ten thousandths of a inch and they had to send the part to Erie PA - 100 miles away to have a half a thousandth of nickle plated to the part to make it the right size. Now all of this sounds big time, but he was working on a shaft for a steel mill (Timken) and the lathe that he was cutting this part on was made in 1929. There was probably half a thousandth of dirt on the part. |
|
#5
02-27-10, 09:17 PM
| |||
| |||
| Quote:
We had a custom Ross in the mid 2000's with a huge dome that netted almost 16:1, and proved 40% winning percentage |
|
#6
03-02-10, 08:46 AM
| |||
| |||
| Chevy heads are 23* and not 18* So the pistons you had were custom pistons and not off the shelf and you could not interchange 23* high dome pistons and SBC 1 heads and the Vortec heads with the same pistons. That was my point! Those fast burn heads are ok where you have a track that mandates a production head - unmolested and flat top piston rule. But the cheapest Dart Iron Eagle head is 100 times better then the Vortec head with twice as much work put into it. |
|
#7
03-02-10, 11:01 AM
| |||
| |||
| Wrong on all accounts, the Vortec head is every bit as good and torque wise better than the Dart (even the Platnium). Not to mention that the OEM Vortec is only 6lbs heavier than a aluminum head, whereas the Dart is 50lbs each The Ross 99480 piston is a 18* shelf pop up with a 6cc dome, but it works fine (as do many other 18*) in a 23* head. No real need to do it now though, cause there is now all kinds of pistons for the heart shaped chambers. But when we did it in 1999, there was no such piston to fit those chambers, so that concept of the 99480 came from the Bartels HD Late Model teams engine builders Still runs great today, after 5 track championships The small Bowtie vortec is the best cast iron (under 200cc) on the market today They will support 540hp, and we got 508hp out of them with a 360 on a stock 4412 Last edited by Brane Sturgeon; 03-02-10 at 11:10 AM. |
|
#8
03-02-10, 03:51 PM
| ||||
| ||||
| Quote:
508hp at the crank or at the wheels? I'm real interested cause we are doing a build right now using that same combo. The Small port bowtie heads with a 4412 carb. I plan on putting it on our chassis dyno and I needed a target to shoot for. I think you just gave me that target. Bobby K |
|
#9
03-02-10, 05:31 PM
| |||
| |||
| Quote:
The 508hp was at the flywheel on VP Q16 fuel, it did 495hp on sunoco maximal @32* timing (we burned up alot of stuff over the years before we figured 32* IS the spot on the fast burn Vortecs). Most 360 cuin Super Streets are in the 440-480hp range, the owner from VDL carbs said that is a very stout number, and the very best ASA car currently make about 520hp Those #s were with a 35lb Crower dieheidral crank, 16:1 compression, Arrow 6.200 x Honda rods (505 gms) and a custom CP 357gm dome piston. Peterson wide vac external wet sump, pulling 14" of vacuum on the crankcase, Tech-line internal coatings on every component (thermal barriers, oil shedders, dry films etc. Awsome smooth power says Chris, like an electric motor. We won 2 open SS shows in 09 (against 4bbl any cube cars) on that 2bbl motor  |
|
#10
03-02-10, 05:40 PM
| |||
| |||
 |
|
| Thread Tools | Search this Thread |
| Display Modes | |
Linear Mode
| |
All times are GMT -8. The time now is 12:35 AM.
Copyright © 2010 PowerTV Media, LLC. All rights reserved.
