Was wondering if the 4-71 super charger with dual Stromberg 97's on a Flathead Ford V8 is worth the expense? Who sales a good qaulity set up that's era correct with V belts? Looking for a early 50's style set up. What can of power and torque increase can I expect? I'm thinking 225 HP Max. I don't expect over 250 HP.
There is a thread on here about an A V8 roadster build & it looks like a 4-71. Search it ?? What's the engine going in? You may wanna post on The Ford Barn too. What is the loco in your avatar..?..i love Pennsy K-4 & 5s , Y-6-bs to name a few.
I did it. I suggest buying Joe Abbins book on the subject and follow it letter for letter. Build the bottom end as well as possible, don't over boost it, 8 pounds is plenty. I did a ton of porting, CNC main caps, Navarro blower heads, 8:1 compression, .125 over ross pistons on a merc crank. Center 97 until half throttle then you get the other two and you need to be paying attention at that point. Worth the money? Hell yes!!
I did a fairly standard FH build for my 32 roadster and added a Road Runner Engineering blower setup running 5 lbs of boost and it really woke up the motor. It wasn't as impressive as the 471 but I liked it for it's compactness.
I bought Joe's book, then met up with him and chatted blown flatheads. His book has some very interesting data in it and theories, which I think are spot on. The 4-71 displacement can overwhelm a 270 cu.in. flathead. I suggest finding that book, then go from there. I developed a Weiand based blower setup from parts available almost anywhere, H&H has a 4-71 setup, Tom Roberts has a magnusen setup. Most will claim a blown flathead will probably top out around 250 hp unless you get very exotic. It's a fun challenge getting a blower on these things, lots of little details.
I put this together and it's a handful...a 471 on a Mitchell intake, running 8 lbs of boost with a 4:11 rear and skinny tires...oh, and the low first gear in the 700r4 helps a bit too...lol
H&H FlatHeads in SoCal has all the goodies for that installation. Was looking at it at the Roadster Show today. Mike
On a stockish engine ,a 4/71 is too much drag to turn over . Sure , it will look good and it will run . But , this is what you will find . It will be sluggish and boggy till round 3k it will pick up after that . and thats with a stock 5t cam .Not what I call fun to play with .Go with a 3/71 or similar ,and you will save the hassle .
Sorry to go off on a related tangent. I have dreams of mounting a crank-driven 4-71 on a drag race only flathead. No good reason, except for having something unique (?). Has anyone seen such a set-up? Any first-hand tips on details of what would be involved?
Full house is correct,,,,for a street setup,,,,I think a 3/71 would be more suitable. It would require less power to drive and still deliver what you need with correct selection of pulleys. The 3/71 is rated for 213 cu.in,,,,,,,the 4/71 is rated for 284 cu.in. Either way,,,,it will look great and will make the Flathead come alive. Tommy
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