Is getting a stroker kit to increase your displacement as effective as an engine swap to an engine with a bigger displacement?

 

depends on what your doing. if going from 350 to 383, since 383 wasn't factory cid then its not the same.

 

Cubic inches is cubic inches. The bigger the bore to start with, the better, though. Stroking a 305 into a 334 isnt really very smart when it's easier and cheaper to just get a 350 and you'll make more power with a 350. A 350 stroked to a 383 is cool because 400 blocks are not common, but in a perfect world the 400 would be better. But theres some weird things about 400s.

 

Bore makes HP. Stroke makes torque. A 302, 327 and 350 all have a 4" bore. A 327 is a stroked 302. A 350 is a stroked 327. Using the longer stroke from a 400 in a 350 and boring it out .030" makes a 383.

Technically on a dyno, if all these engines used the exact same components, they would all make the same HP at the same rpm however the torque would be different in each. You're not however going to use heads or a cam designed for a 302 or 327 in a 350 or 383 as it would restrict the engine's potential.

 

Can we assume you now have a 305?

 

This goes against a lot of the things I know to be true. Is this some kind of layman's definition of things?

Displacement makes torque. Period. More torque means more horsepower, since torque is part of the horsepower equation. All else being equal more displacement will mean more torque but peak power will be lower in the RPM range since the rest of the components werent upgraded to handle the flow of the additional cubic inches. But a 400 will make more torque than 383 will makem ore torque than a 350 than a 327 than a 305.

I dont understand how all else being equal they'd make the same horsepower at the same RPM. That doesn't make much sense either. If the displacement is larger and everything else is equal then it WILL make more torque, and that, by defnition means more horsepower assuming the rest of the motor can handle the increased high RPM flow. You could perhaps argue that you could put a big cam in a 305 and it make the same horsepower as the same cam in a 400 but the 400 will be a much more streetable engine because it makes so much more torque. But they're not making the same power at the same RPMs.

Im not saying you're wrong necessarily it just seems contradictory to what I know and Im trying to reconcile that.

 

If you were to build 2 identical displacement engines, one with a bigger bore to reach the cubes & the other with a bigger stroke to reach the cubes? The bigger stroke will have the higher torque.

Granted, you can't reach the SAME cubic inches in both variations of builds, I'm not saying you can.....But you get the point, which is grounded in fact.

AlkyIROC's example proves the point. 302s rev like crazy, make HP, but so so much torque. As the stroke increases to the 327 then to the 350, the torque goes up.

 

When I say all things being equal, that means same compression ratio, same camshaft, same heads etc. The only difference is the displacement. A 302 and 305 are technically close enough to the same displacement to use as an example. If both these engines were built identically, you would have to put 305 heads on the 302 because the larger valve of the 302 would not fit into the bore of the 305. So take a 302 and use 305 heads and cam and make sure the compression ratio is the same. The 302 will make more HP than the 305 because of it's larger bore but won't make as much torque as the 305.

A 383 is a stroked 350 but also has a very slight increase in bore. Since it uses the same stroke as a 400, the 383 and 400 will make the same amount of torque but a 400's larger bore will make more HP than a 383 or 350.

If you want to see how bore and stroke affect the HP and torque curve, use DD2000 and build a theoretical engine then play with displacement. Make a 302 and see where the power levels are. Then bump it up to a 327 and then to a 350. Since you're not changing any other parts or specs, you can see how the torque will increase.

Doing this in real life is very difficult. As displacement is increased, if you still used heads and cam from a smaller engine, the bigger engine will be really restricted. A bigger engine needs bigger heads to feed it and a wild cam in a small engine can be tame in a bigger engine.

A stock 400 SBC is no match for a stock 396 BBC even with bore and stroke. Although they are very similar in size, the BBC has much better flowing heads to easily make more power. The increased weight of the engine is offset by the extra power it can create.

Displacement will always increase power levels but how that displacement is achieved will determine how much extra HP or torque the engine can make. The larger you go, the more problems occur. My engine has a 4.5" bore. When you get into the big, big blocks with a 5" bore, getting a flame front across the piston in a short amount of time becomes very difficult. Different heads with different valve angles, spark plug location and combustion chamber shape help out a lot.

 

at what point does it become better to use heads that allow two spark plugs?
i know ive seen engines like this before, possibly on top fuel cars...

 

An engine's "Revving" ability has a whole lot more to do with the top end than it does any kind of bore/stroke ratio.

Ford 302's are not "Rev monsters" out of the box. Same stroke and bore as the Chevy one...

 

Wow I never knew any of this. Alright here's a quick back story to why I asked: Was talking to one of my family members about what I'd do if my engine blew and I said I'd probably just swap a 350 in there because from what I've heard you get more 'bang for you buck' He said "why wouldn't you just rebuild and put a stroker kit in it?" That left me with these questions:

Would you get the same HP and torque from a stroked 305
What would be more expensive - the 350 swap or the stroker kit idea
Would putting stroker kit in my current block decrease the durability

 

Your right foot & your brain have more to do with durability, than anything else (provided an engine is built good, as far as clearances, tolerances, etc.).

 

So a stroker kit would not make make the engine more vulnerable to damage than without it? Based on what I read on Wikipedia I assumed that a 350 would have more structural integrity

 

A .030 overbore (part of what a 383 requires) is perfectly safe. .060 is OK, but not ideal Any more than that & the walls are getting thin, thus increasing the possibility (just a possibility, nothing definite) or impending disaster.

Overheating ANY engine, regardless of size/bore/stroke or hammering the throttle every day, reduces it's life. Pure, dedicated drag engines don't have real long lives, because they are hammered on so much.

Treat your engine good & it will treat you god back. I have 210,000 miles in my 1987 350 & still get 21mpg. I treat it right, change my oil, and don't race it. Doesn't mean I don't have "fun" with my right foot, but I don't do that every day or every time I drive.

 

theoretically, the 305 will have more integrity because it has thicker walls than the 350... less space taken up by the cylinder bores gives more metal for strength.
however, a 383 is a very common engine and perfectly durable if built correctly

 

I believe bore and stroke make very little difference to a point, it's all about airflow, one engine with a .5 longer stroke but the exact same displacement as a engine with a bigger bore should make about the same torque and horsepower at about the same RPM IF they are pulling in the same amount of air and fuel. The engine with the smaller bore may make a few more HP due to less ring friction and the big bore engine may work a little better at high RPM due to less piston speed and friction, but I'd run a long stroke for a lower RPM engine and short stroke for higher RPM.

 

To the OP, you can strkoe a 305 to a 334 or so I believe. Basically you use 383 parts balanced for specific strkoer 305 pistons. You basically spend a bunch of extra money getting less than 350 cubic inches. You're much better off just getting a 350 to begin with. Thats why you dont see people strkoing 305's often - just building a 350 is cheaper and makes more power. The larger bore allows for more air to flow through the valves and bigger valves themselves also. That's a big difference too.

THe water jackets are the same thickness on 305s and 350s. Neither has more metal in it. Thats why you cant bore a 305 to a 350.