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Old 05-04-2008, 03:19 PM
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are they all hype????

Ok guys my 383 has a edelbrock rpm performer top end package. If I just change the heads to afr 195 street will I get a noticeable HP gain over the 170 edelbrocks. Went to a car show with 700 plus entrants this weekend and could not find one person with AFRs to pick there brain, what do you think? I'd like to get more torque and HP with better heads. Or are afrs just a major publicity game with all the magazine editors? Thanks for the help.

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Old 05-04-2008, 03:39 PM
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The gain in power will depend on how much of a limiting factor your current heads are. Post detailed info of the entire combination of parts and we might be able to give you a rough estimate.




Larry
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Old 05-04-2008, 04:13 PM
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I'm personally not a fan of AFR heads. Some of them are fine, but they were state of the art in 1985, but they haven't improved them really. They use old chevy port designs and CNC port them with old plots that don't really make use of modern port technology. As a result they typically need big ports to flow big numbers and the result is poor low end performance. The AFR 180s I had on a Firebird LT1 were VERY soggy down low. They also inflate their flow numbers by a good margin. On a flow bench they don't move as much air as advertised.

I guess what I'm saying is, you can do better. Aftermarket heads are great beefy things, but you can usually achieve the same flow with less port volume and the same money with a top notch CNC porting service. For instance, I'm sending some factory aluminum LT1 heads to a respected LT1 porter. When they come back they'll be 180cc runners that flow 260 cfm. That's as good as AFR's 195 cc runner's actual flow. Plus, mine will have CNC profiled chambers, F1-spec 5.1 valve job, fully assembled with larger Manley race valves, beehive springs, titanium retainers, ARP rocker studs, custom bosses added for perimeter bolt valve covers, all for $1700. Expensive, yes, but when you compare it to aftermarket heads its a bargain.

Companies like Edelbrock, Trick Flow, and AFR specialize in high performance bolt-on street heads. They're fine, but nothing to write home about in my opinion. Companies like Dart, Brodix, and others tend to produce either entry level heads that flow so-so, or massive race heads. The smaller heads are designed for race classes where "stock" head types are required, then the racers port the snot out of them, but out of the box they aren't that impressive. The bigger heads are a no-compromise huge port flow game.
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Old 05-04-2008, 05:04 PM
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Curtis, That's a bargain for the parts you're getting plus a complete port job.

Any good builder will give the engine all the airflow it needs to make the most of the combination of parts he has to work with, and not a bit more. As far as flowbenches are concerned, I've seen reductions in airflow numbers after cleaning up the quality of the airflow. This resulted in a gain in power. How's that for a monkeywrench in the flow numbers game?

Airflow comparisons from bench to bench are almost useless unless both benches used the same standards for calibration, and then only if all other variables are measured and taken into account. The size and shape of the clay at the port entry can make a 5% difference in flow numbers so don't take them with a grain of salt. The only thing that matters is the end result.

Horsepower.

All of the companies you mentioned produce heads that do make very healthy amounts of power when combined with the right parts on the right engine. Other companies like All Pro, Profiler, and CHI make extraordinary cylinder heads that can make huge power right out of the box. It's a matter of choosing the correct parts to use ALL of the avaliable airflow, not just a portion of it. That's how efficient power is made.

Anywho, to make a short story long, we can't really answer the fellas questuon until we know what he's working with.



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Old 05-04-2008, 05:37 PM
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Your Edelbrock Performer RPM heads will really really flow air once hand ported.
They are a good out of the box head for what you pay for them and really good, once they are ported.
Tons of potential there. There are practical limitations on a high production as cast head to get a consistant casting integrity (like the valve guide boss contour).
The ultimate shape can only be realized with hand or CNC porting.
You can unlock this power potential with some hand work.

If you're using the edelbrock hyd cam you're leaving a lot on the table.
a recam and some head work will wake it up.

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Old 05-04-2008, 06:30 PM
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F bird is correct I'm using edelbrock cam hydraulic 233/244 at .50 488/510 lift on 112lsa. The heads have 170 runners 64cc chambers, air gap intake, 750 speed demon, 1.5 roller rockers. I don't want to chase a hp number and lose all my driveability just a tire shredder 450-500 torque if possible. Current combo is 323rwhp I can't let the old ladies rousch mustang spank the good old 67 camaro, you know I'll never hear the end of it. Anyways I've read the heads won't allow a 1.6 rockers so lift is limited bt the rpms. thanks for the continuing help
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Old 05-04-2008, 06:46 PM
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forgot to add

I did talk to comp cams and they did suggest a xe284h it has 240/246 at.050 .507/.510 on 110lsa but this was with the afr heads not the edelbrocks. I didn't want to yank motor unless I had to!
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Old 05-04-2008, 06:55 PM
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Quote:
Originally Posted by coldknock
Curtis, That's a bargain for the parts you're getting plus a complete port job.
I even forgot to mention it comes with a matched cam.

Quote:
Any good builder will give the engine all the airflow it needs to make the most of the combination of parts he has to work with, and not a bit more. As far as flowbenches are concerned, I've seen reductions in airflow numbers after cleaning up the quality of the airflow. This resulted in a gain in power. How's that for a monkeywrench in the flow numbers game?
Amen. Flow does not equal dyno, and even if it did, we don't race dynos. Quality is more important than quantity.
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Old 05-04-2008, 07:25 PM
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Quote:
Originally Posted by neverfastenuff
F bird is correct I'm using edelbrock cam hydraulic 233/244 at .50 488/510 lift on 112lsa. The heads have 170 runners 64cc chambers, air gap intake, 750 speed demon, 1.5 roller rockers. I don't want to chase a hp number and lose all my driveability just a tire shredder 450-500 torque if possible. Current combo is 323rwhp I can't let the old ladies rousch mustang spank the good old 67 camaro, you know I'll never hear the end of it. Anyways I've read the heads won't allow a 1.6 rockers so lift is limited bt the rpms. thanks for the continuing help
Forget the chassis dyno numbers and take your car to the track and see what it will do. With some sticky tires. Then open the exhaust and try it. The dyno numbers (from a chassis dyno) don't mean squat.
Those heads are not limited in rocker ratio. Don't know where you got that.
Rockers, by them selves won't help. (+/- a few horses.)
If you want more torque you need a different camshaft and improve the exhaust system (scavedging and flow). New heads or ported head won;t do squat if the exhaust system sucks.
Possibly a single pattern cam with tight LSA 236-236 240-240ish duration 106-108LSA on 102 to 104 intake C/L and high lift.
What trans torque converter are you using. What gear ratio?
Your ignition advance curve probabily -most likely needs work.
Go to the track and get a MPH on the car. It will tell you how much power you're making.

If you don't want to make real meaningful changes and tune it, don't expect improved performance.

Need more info on the engine and car. compression ratio etc etc.
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Old 05-04-2008, 09:03 PM
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[QUOTE=F-BIRD'88]Forget the chassis dyno numbers and take your car to the track and see what it will do. With some sticky tires. Then open the exhaust and try it. The dyno numbers (from a chassis dyno) don't mean squat.
Those heads are not limited in rocker ratio. Don't know where you got that.
Rockers, by them selves won't help. (+/- a few horses.)
If you want more torque you need a different camshaft and improve the exhaust system (scavedging and flow). New heads or ported head won;t do squat if the exhaust system sucks.
Possibly a single pattern cam with tight LSA 236-236 240-240ish duration 106-108LSA on 102 to 104 intake C/L and high lift.
What trans torque converter are you using. What gear ratio?
Your ignition advance curve probabily -most likely needs work.
Go to the track and get a MPH on the car. It will tell you how much power you're making.Need more info on the engine and car. compression ratio etc etc.[/QUOTE


I'm using a th400 with a 10 inch 3000 stall and a davis unified ignition hei with 12 degrees initial and 24 degrees coming in at 3000rpm for 36. This may be the puss way of 1/4 mile time but the best pass with a G tech ran 12.45 at 116mph in 3500lb 67 camaro with 3.90 gears. I'm definately not concerned of making changes to combo just want to get it right, and I probably over analzye everything. Exhaust is 1 3/4 long tube hookers with 2.5 exhaust h-pipe and spin tech mufflers hopefully it breaths well.



]
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Old 05-04-2008, 09:24 PM
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The Edelbrock RPM is a nice head and has a decent combustion chamber, although not the latest tech. If you went to an AFR head you'd want to go to the 195 and you'll gain almost 60 CFM at peak. You'll have flow gains throughout the lift in fact. You will gain a much better combustion chamber, lighter valves and all the latest trick and trinkets. If you can get a decent price for your old heads, would be a decent upgrade.

Curtis, after using these heads since the early mid 90's I have not found anything you said to be true, either on the flowbench or on the track. I'm suspecting you have no first hand experience with these heads.
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Old 05-04-2008, 09:33 PM
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well 116MPH (if that is accurate) indicates a lot more than 323 net hp.
Get to the track on a test and tune day and base line the car to see where you are at before jumping to conclusions.
You probabily be better off reversing you advance curve set up.
24 initial+ 12deg advance for 36 total. Much more responsive.
A few 10th's off the ET right there.
I use a older Vericom computer to test and tune but back it up with radar and track clocks. Its consistant for the most part, but does give eronious fluke data once in a while. The G Tech is not as accurate overall and can give some wild numbers too. But will work as a tuning tool to show gains and losses in performance if you make multiple runs per tuning change and evaluate that based on average gains.
What is your performance goal? I've seen the rpm heads really wake up with decent porting on a buds 383. The potential is there.
Like I posted earlier, get to the track and get a base line and weight the car and go from there.

Your converter is modest for that cam. It's the minimum required. The track et slip will tell the tale (60ft times).
There is much more performance/$$$ invested to be gained by optimizing your overall combo than just swapping the heads.
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Old 05-04-2008, 09:43 PM
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Quote:
Originally Posted by Rick WI
Curtis, after using these heads since the early mid 90's I have not found anything you said to be true, either on the flowbench or on the track. I'm suspecting you have no first hand experience with these heads.
I've had close personal experience with three sets of AFR heads. I had some 195s on a 95 F-body, briefly a set of 180s on a 96 B-body, and I built an AFR-headed LT1 motor for my friend's firebird. All three were VERY disappointing, on the dyno, the flowbench, and the track. The CNC porting was terrible, in spots missing the walls entirely, in other places biting off too much causing galling of the aluminum. One set was shipped to me with a crack beside a guide and they refused to replace it. I called, they refused to replace it, told me to get a lawyer and then hung up the phone on me. So I got a lawyer and got them replaced. All of a sudden they were my best friends. I called their bluff and after they received a letter from a lawyer they caved like a sand castle in the surf.

I made the mistake of trusting their advertising, then I made the mistake of using their heads. I was disappointed all three times. Don't get me wrong... the heads aren't terrible. They flow respectably, but they don't really have anything special about them. I'll be getting the same flow from 15cc less runner for $800 cheaper with my porter, so I don't see what all the love is for. Sure AFR heads are fine. The company sucks, but the heads are vaguely respectable. I just recommend against them because you can get so much more quality for less money elsewhere.
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Old 05-04-2008, 11:10 PM
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I guess I have to say, and end my part of the discussion with I don't believe it.
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Old 05-05-2008, 02:53 AM
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I think most wouldn't believe it, but having lived within 10 miles of AFR's facility for the last almost decade, been to their facility a dozen times, having been disappointed by three sets of their heads, and been told by their employees that in order to get non-cracked heads I need to hire a lawyer, I think I can authoritatively speak on my opinion of the company and their product.

Also, numbers don't lie. I'm not sure why anyone would spend $2500 for a 265 cfm 195cc AFR head when they can get 260 cfm from a 180 cc ported head for $1700. I just don't subscribe to the hype and propoganda. I DO subscribe to a respected porting company who has countless timeslips to represent their product. AFR has knowingly inflated their flow numbers, their port shapes and contours are based on nearly 20 year old designs as I personally verified by touring their shop and personally seeing their CNC machine.

They just don't do it for me. Call me grassroots, but when I'm looking at the best bang for the buck, it becomes pretty obvious. $2500 for a huge-port race head that flows street/strip numbers, or a ported street head that flows race numbers for $1700. No contest.

Even if NONE of my story were true, you can't ignore the numbers. Forget the poor customer service or my dyno time... I can't accept the flow/port size/cost ratio calculation with AFR heads. The bottom line is that they need a lot more port volume to generate the same flow as other heads, and to add insult to injury, their numbers tend to be inflated.

We can agree to disagree, but the verifiable numbers are clearly published all over the internet. I respect your love for AFR, I just interpret the data differently.
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