Big inches with all the typical speed goodies, amatuer built:150; same professionally built 180; all out race on alchohol: 200; same on fuel: 250; blown on fuel 300+. Those are my estimates based on what I've read of current activity. Way back "in the day" there were a lot of higher numbers floating around but usually not based on dyno runs.
I'm running 298bhp on pump gas and 365bhp on gas with nitros. I get the car check on a dyno at the start of ever year just to see if what i have done over the winter has made any improvement.
Joe Abbin recently coaxed 216hp out of a 276" engine NA & then bolted a blower on with 6-6.5psi boost & churned out 335hp - he backed it up with a 12.41 @ 107mph in his '34 Tudor... I think most amateur-built, pure street flatheads are running 160-185hp with the occasional bump up near 200hp. Amateur blown flattys are running 250-260hp - easy.
Certainly not streetable, but it does illustrate the possibilities -- the Tardel-McKenzie motor: 286 cid, injected 6-71 on alcohol -- 431 hp at the rear wheels on Flowmaster's chasssis dyno.
Here is my lazy-one : 241 cu.in/Relived/mild porting / 8.25 comp/Howard 3/4 Race-cam/Johnson adjustable lifters/Edelbrock heads/ Edelbrock "Slingshot" intake/ dual 97 Strombergs/harmon-collins ignition/Fenton headers .... a Wopping 140 BHP ... I hope .. Klaz
Hi Guys, There is a couple books by Aussie flathead guru Mike Davidson with some spec sheets/dyno charts. I'll try and track them down. Danny
My stock 85hp `41 accellerates like it has a modern 185hp engine. I was astonished how well it pulled through the north Georgis mountains on a recent trip. Runs out of breath at 70 mph with the trans and gearing it has. Maybe it's the excellent torque curve that Flatheads produce that gives them the "spunky" feel?
It's all in the gearing my friend. modern cars also cruise at 80. The tourque curve also has a lot to do with it.
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