Well then under what circumstances would any skilled FE builder choose a 4.125" stroke over a 4.250" stroke (not counting the specific request of the customer)?
Cobra Make, Engine: Some polish thing... With some old engine
Posts: 2,286
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Quote:
Originally Posted by patrickt
Well then under what circumstances would any skilled FE builder choose a 4.125" stroke over a 4.250" stroke (not counting the specific request of the customer)?
When he uses a dual plane intake vs a single plane
From what I've learned - It's all about the combination.
Patrick, if there was a displacement rule and a cylinder head rule, then you could opt for a shorter stroke. Sometimes we favor an oversquare situation because the larger bore will take advantage of the cylinder head/valve size.
AL, you have to be completely blind (or just have too much pride to admit it) to ignore the fact that there are 5.5" stroke engines that run at 9000 rpm.
Again, you can NOT use generalizations when speaking of engines.
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 22,025
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No, no rule limitations involved. If you believe the answer is that there is never a reason that a skilled FE builder would opt for a 4.125" stroke (other than a race class restriction rule of some sort) then you should say so. Is a rule limitation the only time you can think of?
In a street car, I would rather have the cubes. I don't know why anyone would logically settle for a smaller stroke when the longer stroke rotating assemblies cost exactly the same.
In a race car, I would rather have the cubes. Pat Musi builds Mountain Motor class Pro Stock engines. They are 903-1000 cubic inch engines. They turn very high rpms and they are very undersquare.
In roundy-round applications such as dirt track racing, common engine sizes are 427-434 cubic inches. These engines turn 8000-9000 rpm, with the largest stroke they can fit in the block due to piston height constraints. These are applications where they require on/off switch style engine response. The stroke doesn't hinder that.
Jay Brown builds FE SOHC engines. He keeps increasing the stroke and I believe is up to a 4.600" stroke with a custom billet crank. He's approaching 8000 rpm with this engine and doesn't he use it in his Drag Week car?
I think we all may not still be on the same common ground as far as terminology and what's going through our minds. I'm still confused on whether we are comparing equal engines, or if we are comparing "potentials." I also think that some people's judgment may have been clouded by low compression, short cammed truck engines with 50 lb flywheels.
... AL, you have to be completely blind (or just have too much pride to admit it) to ignore the fact that there are 5.5" stroke engines that run at 9000 rpm.
Again, you can NOT use generalizations when speaking of engines.
But I can use generalizations as most cobra enthusiasts do not buy super trick builds costing upwards of $30K and more. What does that 5.5" stroker that revs to 9000 RPM cost? Better yet, what are the chances there is a member here with such a motor, slim and none.
That's been your problem with this debate all along, you fail to see that for the common enthusiast, certain general rules do apply and are totally applicable to the motors they consider for these cars. They are not exotic limited production builds that you continually reference as your "examples", that's just nuts, no one here uses them in these cars.
Here's the general reality for the guys that want to keep it reasonable in the motor department, and what they consider when making their decisions. Bore to Stroke Ratio & Other Design Concerns
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But I can use generalizations as most cobra enthusiasts do not buy super trick builds costing upwards of $30K and more. What does that 5.5" stroker that revs to 9000 RPM cost? Better yet, what are the chances there is a member here with such a motor, slim and none.
That's been your problem with this debate all along, you fail to see that for the common enthusiast, certain general rules do apply and are totally applicable to the motors they consider for these cars. They are not exotic limited production builds that you continually reference as your "examples", that's just nuts, no one here uses them in these cars.
Here's the general reality for the guys that want to keep it reasonable in the motor department, and what they consider when making their decisions. Bore to Stroke Ratio & Other Design Concerns
.
This discussion has not been about money, and you're well aware of that. Here, have another straw....
This discussion has been about your need to troll each thread that involves talking about crankshaft stroke, and inserting your completely incorrect generalizations.
And BTW, we all know that racier parts cost more. Did you end up using that Superlight crankshaft that you listed for your engine? If you want to talk about staying reasonable in the engine department, I would make the argument that you don't spend $1200 for a Superlight crankshaft in a low rpm, low compression street motor.
But I can use generalizations as most cobra enthusiasts do not buy super trick builds costing upwards of $30K and more. What does that 5.5" stroker that revs to 9000 RPM cost? Better yet, what are the chances there is a member here with such a motor, slim and none.
It's not mine, but my good friend has put this 5.7" stroke motor into his street car. Sounds like it revs just fine for a pump gas street engine
Cobra Make, Engine: Contemporary Classics, red white stripes
Posts: 139
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Hi Barry,
There are plenty of reasons why someone would choose a shorter stroke in a street car. HP is important, but that isn't the only consideration for a hobby car.
Personally, I want a 427 so I don't have to explain myself at every gas station (why isn't it a 427?), and also because I have always wanted a 427 side oiler. It's weird. I know that a 427 and 428 perform about the same, but I still want a 427 side oiler. Everyone needs to own an icon at least once.
I can build a 4.25x4.25 side oiler, and I might. But I don't need the extra stroke. This is mostly a street car for me.
Btw, I agree with everything else you said about 428 vs. 427. I had a 428 in a Mustang about 15 years ago, and to this date, it was the fastest (and quickest revving) car I have driven. Other cars I have driven include Pantera, Viper, Ferrari, and a supercharged 5.0 Mustang. That isn't a long list, but they're not slouches either. My point is that my 428 had a 3.98" stroke, and it was scary fast. It revved much faster than my 93 Mustang Cobra, which had a 3" stroke.
Here's a better one. My Pantera had a stock 351C when I bought it. I rebuilt it and stroked it to 377". The 377 revved much faster than the 351C, and the only thing I changed was the crank, rods, pistons. It currently has a 4" crank for 408". I'm not quite finished with it, so I don't know how it will behave, but I doubt that it will run out of wind at the top end.
Cobra Make, Engine: Contemporary Classics, red white stripes
Posts: 139
Not Ranked
Hi Barry,
There are plenty of reasons why someone would choose a shorter stroke in a street car. HP is important, but that isn't the only consideration for a hobby car.
Personally, I want a 427 so I don't have to explain myself at every gas station (why isn't it a 427?), and also because I have always wanted a 427 side oiler. It's weird. I know that a 427 and 428 perform about the same, but I still want a 427 side oiler. Everyone needs to own an icon at least once.
I can build a 4.25x4.25 side oiler, and I might. But I don't need the extra stroke. This is mostly a street car for me.
Btw, I agree with everything else you said about 428 vs. 427. I had a 428 in a Mustang about 15 years ago, and to this date, it was the fastest (and quickest revving) car I have driven. Other cars I have driven include Pantera, Viper, Ferrari, and a supercharged 5.0 Mustang. That isn't a long list, but they're not slouches either. My point is that my 428 had a 3.98" stroke, and it was scary fast. It revved much faster than my 93 Mustang Cobra, which had a 3" stroke.
Here's a better one. My Pantera had a stock 351C when I bought it. I rebuilt it and stroked it to 377". The 377 revved much faster than the 351C, and the only thing I changed was the crank, rods, pistons. It currently has a 4" crank for 408". I'm not quite finished with it, so I don't know how it will behave, but I doubt that it will run out of wind at the top end.
Cobra Make, Engine: Unique #9159 428 FE 614HP by FE Specialties
Posts: 257
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I have a 428 600+ HP with 11.4 compression dual 660 Hollies on a tunnel wedge. It sounds wicked but it's manageable on the street and a screamer on the track. 13,000+ miles without any problems.... Hope I haven't jinxed myself.....wouldn't have any other for the money. Tom Lucas did an awesome job.
Yes, and just "a cool $115,000 shipped to your door!"
My uncle Bob in Iowa can make a tractor motor rev to 10K for $115,000.
But let's see those mountain motor cobras, must be an awesome sight eh!
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Then you should have called your uncle bob and asked him about stroke and rpms, because he could have set you straight.
Good one brent............
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