BIG BORE VS BIG STROKE-372 VS 383-WHICH SBC STROKER DOES IT BEST? BONUS TEST-302 VS 347 FORD

Why do you say food pounds but type it as pound feet?

So why not use the big bore block with the larger stroke?

Why pick one? Do the stroker crank and the big bore. A 427 small block would kick ass beyond what these would be capable to.

Second half of the video was great! I have a 305 and thinking about making it a 334 and leaving the heads, intake, and carb the same but wasn't sure if it would work. This pretty much confirms it would and would give the gains in low end power I am looking for. Most bolt on power only helps at the top end and hurts the low end. Spinning an engine over 5k rpm doesn't have much real world application.

It's Christmas I'll be nice

If I have that block I would not ever build a 372, it would be a 420 or 427ci.

How about a stroker motor with a Roots blower? That's got to make some massive torque!

That 383 needed more camshaft

I like bigger bore most of the time.

My 377 big bore made 597 hp at 6400... with brodix trac 1 heads. A 669 lunati roller. 112lsa 500hp at 5k and still 500hp at 8k the point everyone misses we don't race dynos, the 372 will flat stomp the 383 on the track, example you'll be pulling 30 to 40 more points in the gear. That multiplies torque. We raced a 311 inch motor against 358 motors and pulled them 3 car lengths down the straits on a 1/2 mile track we were turning it over 8800rpm and we were mild on the gearing coulda turned the motor 9200 easy. People need to realize that. 99% of all Passing in done from the middle of the corner to the flag stand. That 30,40,50 points in gearing will do that.

It wouldve been more telling if the 350 block WASNT bored out and had the 4.0 bore making a 377 vs the destroked 400 or 372

The 302 v 347 thing has been done before, Pontiac has been doing that from the factory since the V8 came out. You can put the same top end and cam in a 350, 400, 428, and 455 to see how much difference displacement makes. You can also see what happens when you increase airflow through the heads on those engines.

Only the 350 is small enough to move the torque band up with increased airflow. The 400, 428, and 455 all simply make more torque through the entire RPM range. Thats because the runners are the same length on every one of the, and that is where the torque comes from. The ports are kinda small for a 400 inch and larger engine, so the power band doesn't move much in the RPM range, it just gets bigger.

Pontiac is fun, because the main differences between the 400 and the 428 are main journal diameter and stroke, 3.75" vs 4" and the 400 vs 455 is .030" bore and a 4.21" stroke. You can get crank kits for the 400 block with 4, 4.21, 4.25, 4.35, and 4.5 inch strokes, that cost about the same as grinding a stock crank, adding forged rods, and new pistons. So why not make that 400 into a bigger engine?

The grunt from a 455 is addictive... especially with a 2.73 to 3.55 gear behind it. The 455 in my 65 GTO is pushing a 3.08 gear, and it pushes you into your seat far harder and longer than a car with a 4.56 gear does.... provided the tires don't go up in smoke. As long as you don't think more's better with gear like its a sbc, the Pontiac is an inexpensive way to the low 12s to high tens.

The problem is you aren't finding these engines in most junkyards, you have to find the entire car most of the time (usually 4 doors), and that is getting harder too.

If you weren't so far away Rich, I would bring stock and modified 400 and 455 engines for you to test. Might be fun finding out how much power my latest build with the tunnel ram makes. Its raining again today, otherwise some dragy runs would be happening. Maybe tomorrow morning, since its Sunday and the traffic will be lighter.. if its not moist.

For the 372 vs 383 there are too many variables to pin down where the difference comes from. Even with identical piston relief, head cc, gasket thickness and deck height the 383 will have about 1/2 a point more static compression. Then you get into dynamic compression being effected by the cam and even rod length. I think if you simply swapped the same H/C/I from one engine to the other, both with at least nearly the same static compression ratios, the results would be much closer.

And for the guys that say "long stroke=torque and short stroke=RPM" I ask what about the 403 Olds? It had a bigger bore than the Chevy 400(4.351 vs 4.125) and a shorter stroke than the Chevy 350(3.385 vs 3.48). When it was introduced in 1977 it made more peak torque(320lb-ft) than the previous year Chevy 400 out of an Impala(305lb-ft) at only 200 RPM higher.

The 403 was put in giant full frame sedans, station wagons and even GMC motorhomes by the way. Hardly applications suited for a "high RMP engine with no low end torque"...

RICHARD, DO A DESTROKED CHEVY BIG BLOCK BUILD. A CRANK FROM A 348W ENGINE FITS RIGHT IN. REHER-MORRISON BUILT ONE AND I THINK IT WAS 358ci. THEY RACED IT IN PRO STOCK YEARS BACK BEFORE THOSE CHEATERS THE NHRA, WHO WERE IN THE POCKETS OF GM. MANDATED THE 500 CUBIC INCH RULE. IT DID VERY WELL. IT WOULD BE INTERESTING TO PUT IT AGAINST THE CHEVY SMALL BLOCKS OF ITS ERA WHICH WERE THE 331 CUBIC AND DO A SHOOTOUT.

What rod lengths were used in the 372 vs 383 comparison? Rod/stroke ratio plays a large factor on how these engines perform.
400 Chevys suffer from a stock 5.565 short rod length to allow for the longer crank stroke. With expensive pistons, they gain with a longer 5.7 rod like all the other small blocks, and even more with a 6.00 rod.
If both engines were built as truck towing engines with same comp, cam, heads, intake, carb, etc, I would bet that the 372 would outlast the 383 if all else is the same. Rod/stroke ratio, meaning a short rod will put a lot of piston sideload from the crank throw. This is the same reason that lower RPM engines, like farm tractors, typically have the crank stroke to be larger than the piston bore, and the connecting rods to have approx 1.75 ratio to the crank.
327 Chevy, 3.25 stroke, 5.7 rod=1.5 rod stroke ratio that will RPM nicely, and the piston life is good in a street engine.

Id rather have the higher reving engine

Bigger Bore to achieve the same cubic inches almost always wins out

I think the 383 does better in the lower rpm because of the stroke length. And not the "leverage" argument. The longer stroke produces faster puston acceleration amd piston speed, creating a bigger pressure differential that really helps scavenging and getting a bigger fresh air/fuel charge into the cylinder. At higher rpm, this velocoty becomes less important than bulk flow, and the bigger bore helps the head to flow more at higher rpm, giving the 372 the advantage. I wish you could do this test with a .060 over 400 block, giving g a 382 vs 383 test, which is taking the cubic inch variable out (since we all know torque potential is a product of displacement) and do a real A B test.

Big bore usually will make more peak HP. Let's the heads flow more

Different cam, heads, intake..Not a good comparison. Needs to be the exact combo except for bore and stroke to be a real test. JMO.

I’ve been requesting this for years. Thank you

My question is. Which one is better for the 1/4 or 1/8 mile? High end horsepower or low end torque

Richard if you are going to do a comparison please use the same parts on both engines

If you want to win stroke it period.

Different combinations...
LSA lol In all seriousness, I would have at least ran the same LSA.
Just my opinion

Re 372 4.125x3.48 vs 383 4.03x3.75

I tune lots of bike engines. I see both configurations in similar displacements.

Torque falls off more the more over square. Horsepower goes up from breathing and more esoteric things like sqirl and squish.

So if you can benefit from increasing headflow from increasing bore and unshrouding the valves then thats the beat option. If the heads arent all that great then stroke increase would be more important?

The interesting bit is if you gear the 372 to peak at the same MPH as the 383. Having the 372 shift when the 383 does at 6100rpm would net a 10% better gear ratio for the 372, which would multiply torque at the wheels - inflating the peak to 524lbs up from 477. It would end up faster than the 383 everywhere.

Here is a test I would love to see. 421/427 SBC and SBF. Both use aftermarket blocks and rotating Assembles, Both should run 11.0:1 compression, Both use very similar camshaft design, both use AFR 225cc to 227cc CNC cylinder heads, both use Similar size intakes and the kicker? both use 950-1050 CFM carburetor. Here is the bore and stroke, 4.185" bore to 3.875" stroke. Let the war begin.

Old Ford guys very familiar with long stroke larger displacement engines w/ poor airflow back in the '60s. Mucho torque on the low end. Great truck engines.

I think just bore it stroke it to 427 be done with it lol!!
Idk think id go with the 383 all that torque would be fun definitely for st. Maybe the 372 for race track but still think the 383 be better all around for sure.

Richard, when it comes to 383 vs 372 in the small block Chevy why choose? The correct answer is you bore out a 400 and make a 406! I would even trade a 383 to get a 400! I would never destroke a 400 on the grounds of "I want it to rev" on the street. In short, have your cake and eat it too!

I think the wrong block was bored .030 over. Would have liked to have seen a 377 vs 378

Look at things from the Crankshaft point of view. A destroke 372\3.48" is like a very good running 350. And it doesn't have to be a high revving motor. I've always felt one of these would make a great Street Blower Motor for a Weiand 144 or for a Turbo if you want the higher RPM's.

I prefer short stroke and big bore

By the way- Foot pounds of torque is for linear torque. Pound feet is for rotary torque- please use the correct designation- pound feet.

I have a 1963 Ford Falcon that came with 260. I now have 302 with 1969 351W heads. A 351 will not fit in the engine compartment without serious modifications. So a 347 might be good. But the 302 is sufficient.

Uncle swore by the 377(400block-350 crank) in the sprintcar. Did not need gobs of tq, but the extended rpm help with tractable tq for a very light car.
The tow/hauler ran a 383-more drivable tq. Both motors were very different tho. But who doesn't like a rooting tootin gross pollutin high revin sbc?

With regards to stroke vs. bore, it's all about use case.
I have a 3/4 Ton Suburban, and not long after I got it, I replaced the 350 with a GMPP HT383E. I have zero regrets about that choice. It didn't just give me more power, but it gave it to me where I especially wanted it, down low. It gets that heavy truck moving so much easier, and it's a tow beast a well. Plus, it will power through heavy snow and dirt with ease.
That said, back in my youth I had a buddy with a really lightweight Nova with a 327, and that high RPM power curve was perfect. I'd love to see it scream with a high revving 372 with 2.02/1.60 valved heads.

A great example of boredom vs stroke would be a SBC 302 vs a SBC 305, vs a 350 SBC with the bore and stoke of both of those engines.

This was interesting as most of Richards tests.
Dyno numbers are not always the same as what the engine does in a car.

9.5 deck FTW

This comparison is a great example of why we should be using area under the curve instead of just peak numbers.

383 all day especially for a footbrake class

On the Ford 302, First I would do is change the heads like a set AFR 195 or the bigger valved heads for Ford small Blocks. Yes a 351 Windsor would also be a great choice like building a a 408 for example. a fun engine to me would be building a 331 stroker bored 030 over and use a great set of heads, a great cam and maybe add a turbo to it. I would use a aftermarket block like a Dart shp block and appropriate bottom end parts and pistons to handle the high rpm it would it can rev to and put in something light like a 19631/2-1965 Falcon. it would be a lot of fun to drive!

I now understand why Billy from SRC built his 372.

Did a 5.0 HO swap on my purchased new 1987 TBird Turbocoupe. Super budget I torque ported the stock heads and intake, ran an E303 cam and 1.5" shorty headers. Never replaced the stock valve springs (mistake). Made 314tq at 3500rpm and 250hp at only 4700rpm on a Dynojet. As for the low power rpm I never replaced the valve springs or headers but did try an Edelbrock intake with no improvement. Interesting how it compared to the baseline motor above. Was a ton of fun as a street car!