The Stovebolt Site Forums The Shop Area Engine Shop 235 torque and hp curves

does anyone have torque and horsepower curves for a 235? i'd really like to see figures from a 'hot' engine with a cam, 3x1 intake, headers, hot ignition, etc.

thanks!
ed

Don't know the stocker numbers, edmurder; but from what I've read from other posts here (if I remember correctly) a really hot, well balanced 235 can give you 175-200 true HP. I'm guessing peak power around 3000-3500 rpm, after bumping up the cam duration.

While that may not sound particularly impressive, 200 HP is probably a 75-100% increase over stock. If you want more power go with a 261. It's a no-mod bolt-in fit.

Patrick Dykes of Patrick's truck parts says he has seen many modified 235's on dynos.He told me on the phone, 200 hp is generally beyond streetable on a non supercharged engine. He quotes 160-170 for the 235 and maybe 200 for a 261.Jack Halton says a well prepped 302 GMC might make 250 HP for street use with its much better head design. To get big HP numbers you need to go for RPM levels that get the crankshaft harmonics doing all sorts of bad stuff to long term reliability.Or go for a hyper expensive custom alloy head.You could supercharge(exhaust or belt driven), make a mistake here and its a $$$ meltdown.The poor breathing head is the main limiting factor for power , along with the heavy, somewhat poorly supported crankshaft.Besides we are dealing with 50 year old parts here.Leo Sanducci used to drag race all out heavily modified 261's. He claims around 280-300 HP for a drag engine on gasoline.These are vintage engines, keeping the modification in line with reality gives a smooth running engine with almost stock reliability.

It's like an 80 year old guy on speed trying to win the Tour de France. He will go fast but is bound to break his skinny legs...

Did I say 250 HP? That must've been around Unger's campfire when the Chivas was making the rounds!

The only credible dyno tests I've seen were published in the May 1955 "Hot Rod" magazine and reprinted in the March 1983 "12 Port News". The tests were run on the McGurk dyno and started with a bone-stock 261. From a base of 114 BHP at 3500 RPM and 201 lb/ft of torque at 2000 RPM, they went through a series of modifications and ended up with 197 BHP at 4500 RPM and 268 lb/ft at 2000 RPM. This final reading was obtained with 287 cu. in displacement (from a .125 overbore), slipper skirt pistons, Corvette dual exhaust, dual point distributor, a seriously reworked head & valvetrain, triple Stromberg carbs, and a real snorty "super 3/4" grind McGurk solid lifter cam. It was described as being "on the ragged edge of streetability".
Obviously it's hard to critique something published 50 years ago but I'd say the numbers are pretty close. 235/261 hop-up parts being about the same level of technology, I wouldn't expect much more these days. Unless you've a got a big budget for one of the new Wayne CNC alloy 12 port heads, that is.

hey guys-

thanks for the replies, but i think you're headed in the wrong direction! i'm not looking to make a monster motor. well, i am, but i'd be happy with 170 hp. it's going into a '31 coupe, so thst'll be more than enough motorvation.

what i'm really looking for are some actual dyno charts from hopped up 235's. i'd like to use these so i can select a t-5 with ideal gearing and my rear gear. i'm told that these things make torque all over the place, but i'd like to know exactly where.

thanks,
ed

Guys here using 235's with T-5's have been happy with rear gear ratios from 2.73 to 3.90.Your lightweight coupe with a mildly built 235 should be fine with a 2.73-3.08 gear if you are using a S10 T-5 with a 4.03 or 3.50 first gear.If you have the 2.95 first gear Camaro trans, a gear around 3.40-3.73 will be better.As Sixpack says, there is a lack of reliable dyno information.

Hey ed, just for reference...

I have the following mods on my soon-to-be-installed street 292:

- .060 overbore (complete rebuild, block and head)
- Offy single 4 barrel intake modified for water heat
- Edelbrock 500 cfm carb
- Dynomax dual exhaust w/36" runners
- HEI ignition (or mallory dual pt distributor & Accel supercoil)
- aftermarket cam with .464I/.494E lift and 194/204 duration at .050

and I'll still pull only 180-200 hp at best (so I've been told). As you can see the smaller, older sixes take more radical work to make the same power. Consider the 261. The more displacement the better.