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 ch***sis 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 "*****y" 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.
The Jalopy Journal
