FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Brian on February 12, 2021, 04:00:28 PM
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Hi guys awsome forum it is nice to see and hear of other fe fans. But I couldn't help but notice not many people use the shelby Mr head. Is it just due to cost or is there other major problems to make others better? Would there be that much of a loss in power on a street car under .600 lift in comparison to tfs heads. A friend just put a set on an old 427 block with a 4 inch stroker crank. A bad intake choice really killed power, the port matched performer rpm couldn't flow enough. It made good power and torque form 3 grand up but stopped off at only 526 at 5800. Engine builder dyno operator suggested a victor junior would be worth 50hp plus. The motor produced more peak torque than horsepower. Has there been many out there with shelby head expirence out there?
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It was certainly not the intake's fault. That intake manifold will support 600 hp easily. Could have been the camshaft, could have been a number of things, but it's very typical for an engine to produce more peak torque than horsepower. My guess is was the fault of the Shelby heads.
Nobody uses Shelby heads because they are not performers and you have to pay for the name. They flow about what an Edelbrock head flows....about 270cfm. They're down 60 cfm to a Trick Flow head.
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thanks for the response. SO they did b.s. him with the specs.The dyno slips are at buddies the torque from 3000 up was over 500. Yes on you site i have seen 390's hit 500 hp plus.. The motor was done early.. Perhaps it is cam solid lifter roller just under 600 lift. Actually 232 236@.050 .598 590 lift. Myself thought it was the 750 cfm carb it was dyno'd with instead of the new 950 that went with it. It made 529.4@5900 rpm 89 percent ve. We are hoping the bigger carb will help first. Thank you for your help sir we want what we have to run as hard as possible.
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A 427 with a 428 crank is around 455 cubes. That's a pretty small camshaft for an engine that size. You lose effective duration due to lash on a solid cam, so that 232/236 cam is even smaller.
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Working from memory, the Shelby heads had large chambers, of antiquated design...
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I have a pair of Shelby aluminum heads that were cnc ported and came on a Craft 482.
They have 2.25 intake and 1.75 exhaust valves.
They flow 305@.600 intake and 204@.600. Rather disappointing considering the port work.
190cc intake port volume and a 81cc chamber.
You can do much better for less money...although the 482 with these heads made 627hp on Craft's dyno.
I'm going to take these heads to my "cylinder head guy" and have a tootsie roll with short side tune up done and see if they pick up any.
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I don't know about the Shelby heads, but Edelbrocks don't flow 270 cfm as purchased. I know Edelbrock says (or used to say?) they flow 270/200 cfm. They just don't.
pl
I guess they still say that:
https://www.edelbrockspeedshop.com/EDELBROCK_PRFRMR_RPM_C_HEADS_72CC_FORD_FE_COMPSING_p/60069.htm
edit: Well the exhaust side is fairly close. The intake no.
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I assumed that the Shelby FE heads were top knotch, so this news is sad.
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I assumed that the Shelby FE heads were top knotch, so this news is sad.
To be fair, the Shelby heads are top notch quality. They were never after maximum horsepower, it was basically just an aluminum version of the Medium Riser head (chamber and all), made for the Shelby Cobra crowd. Why they dropped the ball in not going to a modern chamber is anybodies guess.
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Joe at Denbeste has recently done a redesign on these heads and they are making pretty good flow and power. My problem with them has always been the casting, they are noticeably lighter than a conventional edelbrock head. Not sure who does their castings for them.
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Some pictures of the newer design heads. I think they have been around for about a year now. I have no idea how they flow or perform, just know that they exist.
(https://i.postimg.cc/YqPFtcjj/Shelby-1.jpg) (https://postimages.org/)
(https://i.postimg.cc/zGRgBdR7/Shelby-2.jpg) (https://postimages.org/)
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Maybe just the angle, but those look like fairly large ports.
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The new combustion chamber does look like a substantial improvement.
The Shelby site says 55cc as cast combustion chamber - I like that alot.
Intake port volume 195 cc and 305 cfm - does not mention at what lift.
A very decent starting point for sure - expensive yes.
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Combustion chamber does look nice. 195cc with 305 cfm is pretty stinky compared to a lot of today's offerings.
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The website actually says 310 cfm. Not a big difference, but that is pretty good flow. On the other hand, I'll be my ported Edelbrocks flow more than that when I put big valves in them.
Everybody is fixated on small ports that flow a lot right now. i.e. high velocity. Is there ever any advantage to a bigger slower velocity port?
pl
https://www.shelbyengines.com/collections/all-fe-parts/products/shelby-fe-aluminum-head?variant=167624612
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Everybody is fixated on small ports that flow a lot right now. i.e. high velocity. Is there ever any advantage to a bigger slower velocity port?
pl
Check out Jays response in his "FE Power Cylinder Heads - More Test Results" thread (response #42), which is a reply to the video that Barry posted. If there's one thing that's certain, it's that there are no 'definites" when it comes to engine building. It all depends on combination. The only 'certain' that I know of is that experience rules.
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This is copied from the Stan Weiss website. The info is not too detailed. I'm assuming this is from the old style Shelby heads. Just FYI.
Manufact.
Part Number
Port/Vol Valve Size Int/Exh Comb. Cham. Vol .400 .500 .600 .700
Shelby 427 Alum N/A 2.25/1.75 N/A 241/156 264/175 275/180 279/-
Shelby 427 Alum Stage II Porting N/A 2.25/1.75 N/A 265/185 294/200 309/209 314/214
Shelby 427 Alum 163/128 2.25/1.75 82 280/185
Shelby 427 Alum Stage II Porting N/A 82 320/235
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The website actually says 310 cfm. Not a big difference, but that is pretty good flow. On the other hand, I'll be my ported Edelbrocks flow more than that when I put big valves in them.
Everybody is fixated on small ports that flow a lot right now. i.e. high velocity. Is there ever any advantage to a bigger slower velocity port?
pl
Interesting question, would a 300cfm say 205cc head ever make more power than say a 330cfm 170cc head, or would it only make as much if the big head flowed the same? Guessing it may make more peak but in the car it would actually slow down.
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It seems to me that a high velocity head, would give a wider power band (higher average HP) than a low velocity head, especially in wet flow.
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There will always be a compromise when it comes to "universal" heads.
A large port will feed a large engine but will be sluggish on a small engine (unless it's high rpm application).
A small port will be zippy on a small engine and may feed a large engine up to a certain point and then the head needs more volume to meet the demands.
Choosing the cylinder head for the application is what's necessary. Unfortunately, there are sometimes situations that are dictated by circumstances.
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This is copied from the Stan Weiss website. The info is not too detailed. I'm assuming this is from the old style Shelby heads. Just FYI.
Manufact.
Part Number
Port/Vol Valve Size Int/Exh Comb. Cham. Vol .400 .500 .600 .700
Shelby 427 Alum N/A 2.25/1.75 N/A 241/156 264/175 275/180 279/-
Shelby 427 Alum Stage II Porting N/A 2.25/1.75 N/A 265/185 294/200 309/209 314/214
Shelby 427 Alum 163/128 2.25/1.75 82 280/185
Shelby 427 Alum Stage II Porting N/A 82 320/235
Those numbers look pretty accurate from the Stage II Shelby heads I have.
They are cast by Arias. They are a quality part with slight improvements from the Ford Medium Riser head but still used the Ford chamber.
I got these heads because they were torched out between 7&8. They have since been repaired and are ready to rock 'n roll once more.
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Everybody is fixated on small ports that flow a lot right now. i.e. high velocity. Is there ever any advantage to a bigger slower velocity port?
pl
Check out Jays response in his "FE Power Cylinder Heads - More Test Results" thread (response #42), which is a reply to the video that Barry posted. If there's one thing that's certain, it's that there are no 'definites" when it comes to engine building. It all depends on combination. The only 'certain' that I know of is that experience rules.
Excellent video! I should have watched it when Barry posted it. Thanks for reminding me. Going to have to re-watch it a couple of times and digest it.
pl
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Those numbers look pretty accurate from the Stage II Shelby heads I have.
They are cast by Arias. They are a quality part with slight improvements from the Ford Medium Riser head but still used the Ford chamber.
I got these heads because they were torched out between 7&8. They have since been repaired and are ready to rock 'n roll once more.
Hooray for the repair-ability of aluminum. I imagine those heads will rock 'n roll. :)
pl
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Everybody is fixated on small ports that flow a lot right now. i.e. high velocity. Is there ever any advantage to a bigger slower velocity port?
pl
Check out Jays response in his "FE Power Cylinder Heads - More Test Results" thread (response #42), which is a reply to the video that Barry posted. If there's one thing that's certain, it's that there are no 'definites" when it comes to engine building. It all depends on combination. The only 'certain' that I know of is that experience rules.
The first thing that is interesting to me is how he says velocity affects the short turn radius. My first thought is that a slower speed there would help air and especially fuel make the turn, but apparently that is not the case. A higher velocity reduces pressure there and "pulls" air and fuel around the corner. That is, at least at first, anti-intuitive to me. Then I think of a carburetor venturi speeding up the air (and dropping the pressure) and it makes sense.
edit: Here is Barry's link to Darin Morgan's video from the other thread that Doug mentioned and Jay replied to. whew!
https://www.youtube.com/watch?fbclid=IwAR01CNJWFTT09GrC8SfClQTDHhQcq5lN07vf2ZJaVEIG0jehKcGhOXiZqrs&v=qhsTQn0uUOQ&feature=youtu.be
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I purchased a set of their stage 2 MR heads and after getting them to my engine builder we had them checked for flow and they didnt reach the non ported spects, they took them back stating nobody ever checks them.
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I purchased a set of their stage 2 MR heads and after getting them to my engine builder we had the checked for for flow and they didnt reach the non ported spects, they took them back stating nobody ever checks them.
What did yours flow?
pl