The Stovebolt Site Forums The Shop Area Engine Shop how much power can be squeezed out of a 235

im just wondering about how much power can these 235's make. I have a rebuilt 54 235 in my 52 3/4 ton 5 window that im working on boosting the power a bit. Im purchasing a clifford 2/4bbl aluminum intake manifold with a 4bbl carb adapter plate to mount a holley 4bbl carb and a set of clifford exhaust headers to help boost the power of my 235. Im also looking to purchase a hei distributor as well to help burn the extra fuel more efficiently. On Clifford's website it says that by adding those headers i can expect a 18% to 22% increase in power. What can i expect by adding the intake and 4bbl carb?


So how much torque/horse power has ever been squeezed out of a 235 before. Im not looking to beat the record or anything im just wondering what has been accomplished.

I got the intake, adapter plate and headers for $500 shipped in the "for sale forum" on another site i am on. They were installed, ran once and removed because the person decided to install a v8 instead.

here is the link
http://67-72chevytrucks.com/vboard/showthread.php?p=2642891#post2642891

I have an article in an old truck magazine around here somewhere that had the old 6s running over 600 HP. You can get as much power as you want but it will cost you...

looking at the specs for my motor, which is a powerglide (was taken out of a 54 passenger car), gets around 125hp stock, so if clifford is sure on the 18% to 22% power increase then that should boost it up to around 145hp or so.

here are the specs
http://www.secondchancegarage.com/public/370.cfm

My 235 +.040, 3/4 cam, head milled .040, dual offy w/ Holley/Webers and Fentons desk-top dyno's at 172HP. I have no way of knowing if it's acurate or just sounds good. It will accelerate up a 5=6% grade in high gear from 20MPH so it has good lugging power. It will run 75MPH with stock gears but it is screaming.

Don't go down this path. You will be disappointed.

First, that "600hp" is NOT available from the 216-235 or 261 series of engines. That is only available from the LATER series that has WAY more crankshaft bearings and cana ctually spin some decent rpm without self-destructing.

Secondly, all the inline GM sixes we are discussing lack a fundamental requirement for decent power: a crossflow head (intake on one side, exhaust on the other). The 600 hp quoted was obtained on a lert series engine, with TWO small block V8 heads cuts, welded together, and remachined to make a crossflow head, needed a big supercharger, and had numerous expensive internal engine work including reshaped (not just ported) heads, etc.

The 172 hp predicted by the engine simultaotr program is incorrect because that program has no provisions for modeling a non-crossflow head. This introduces major error.


I went down this path a long way before realizing that it was doomed if you want REAL power. The best deal I could find in a month of looking very hard was a 261 (235 is too small) that could be worked to deliver perhaps as much as 250 crank hp MAXIMUM, and would cost $3500 to $4000 in work, plus shipping both ways, PLUS this assumes that the base engine you provcide is decent. So, really, this is about $5000 to $6500 to get maybe as much as 250 crank hp. There are better ways to spend money.

Note that back in the mid 50s, a famous engine builder puleld out all the stops on a 261 (not 235), that he bored to larger displacement, hand ported, raised compression, put in a cam wild enough that he admitted it was beyond what was streetable, etc, etc,. and got 190 crank hp out of it as his best outcome. So, with today's betetr techbniques and tools, I can beleive the 250 crank hp, but not anything more.

The Stovebolts are wonderful engines when used in reasonable line with their design objectives, but they will never be economically practical or reliable "powerhouses".

But hey, if you have tons of money to spend and don't mind a modest outcome, go for it!

I spent a lot less to get a 6.0 liter GM V8 with a dual carb Edelbrock intake that will deliver between 425 and 505 crank hp, depending on how much room we have for exhaust in my AD truck, and how well the dual carb RPM Air Gap intake performs relative to the proven Edelbrock single carb intake (which is breathtakingly good). And, I can get service and parts for it on a trip anywhere.

Jim G

I know nothing about how horsepower is measured or was measured but the 53-55 (and early 1955?) Corvette 235 engines supposedly produced 150 hp (1958 235 engines supposedly produced 145 hp). The Corvette 235 had three side-draft carburetors and a modified lift (261 truck) camshaft.

The GMC 302 straight six with Wayne "12 port" head supposedly produced 300+ hp.

Here is another interesting article about 235s.

Street Rodder magazine did an article a while back, maybe last fall, on hoppingup a 235, maybe worth checking it out.

Mike

Ask yourself what you are trying to do. If you want a hot rod, or a race car then go with the v-8. If you want a charming old pickup that can shoulder any load and get the job done then stay with the six. Right now I am keeping my 235 because it runs well and doesn't need a lot of work. I have no delusions of pulling HP out of it though. It will chug down the highway at 55-60 and get around town. I think that some power adders are a good idea, but don't expect v-8 horsepower gains in a inline motor.

That being said....do what the hell you want. That is the best part of customizing. Does it matter what we all think? NO!!! This is a truck for you and you alone. Do what you want and let us know how it turns out.

Kyle

i am by no means expecting to get the horsepower of a v8 from my inline 6. My truck is going to be a cruiser, weekend drives and trips to wherever. I have no problems running the inline 6, ive thought about dropping a v8 in but decided id rather run the 235 but with some add ons to make it a bit better (power and economy wise).


pretty much i wasn't wondering what I can get out of my inline 6, but what others have done/seen, just curiosity basically. If i wanted to have neck snapping, tire roasting power then i would drop a v8 in and sell the inline, but thats just not the route i want to take at the moment.

I always thought a 292 would have made a good motor for these trucks. You could probably get it up to the 300 hp level if you worked at it during the rebuild.

I always notice that the V-8 small and big block guys tell you that they can get service and parts on their engine while on a trip anywhere.

I don't know why they always say that, but they do. They always look at me when they say that.

The inline guys never say that.

Joe

yeah ive been starting to notice that as well. And the fact is, we can still get most parts from a local autoparts retailer (ie autozone, advance auto, pepboys, napa and so on) for these t. Now if we are out of town on a road trip or whatever we may need to stay the night at a motel while they special order the part we need but thats the same for newer vehicles too, if it isn't basic parts like filters, spark plugs, distributor cap/rotor and what not, they usually will have to order it.

My 292 equipped with 3 Weber carburetors, reworked head, headers and a reground cam puts out around 350 horsepower which is enough to make most every V-8 thing on the street look up and take notice. The ample torque of the big 6 makes it stronger than the horsepower number would expect. Most V-8 engines of the 350 h.p. range put out about 15 to 20% less torque than the big 6.

Ive always been told you can get a maximum 1.4 horse from every cu. inch, in your motor if you do it right and have everything perfect.

That would put you at about 330 hp.

That caculation may not stand for these older motors and of course doesnt work with the little imports with turbo's the size of their motor.