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Read all you can about motor build ups.

When I first went to a stroker 383 I was suprized about how much more grunt it had. It sure felt bigger than the 30 or so ci change. I think that it has allot to do with the additional mechanical leverage of the longer stroke

 

gkull:
You're correct-o-mundo!
My buddy has built several various SBC (355, 377, 383, 400/406, 421, etc.) for street, drag, and oval-track.
He has also built 377s (400" block/350" crank), and 383 (350" block/400" crank), and altho both make almost identical peak power, the long-arm 383" makes much more torque 'down-low'.
His current favorite is a 383", based on a 4.030"-bore (non-siamesed cylinder walls) 2-bolt block (converted to splayed 4-bolt caps for strength), forged pistons, as well as a 'REAL' crank/rod combination.

 

Typically HP doesn't change as drastically as you'd imagine from one engine size to the next. You will find though that the bigger the ci "typically" the more torque it will make at lower rpms.

Maybe you should research "how do I get all this new power to the ground" :D

 

also if my understanding is correct a 377...a destroked 400 is really good for horsepower but needs to rev really high like 7k plus.....but that's only what i have read.

 

Basically, that's what my buddy tells me;
the 377" (de-stroked 400") is a big-bore 350" (high-RPM power),
and the 383" (stroked 350") is a small-bore 400" (low-end grunt).

The 377" features (4.125"-standard) siamesed-bores, which he feels are a bit more prone to heat-damage, while the 383" uses a 350" (4.000"-bore) block, having 360* water around the cylinders (better cooling), and more 'meat' between the bores, helping head-gasket sealing.

If he begins with an after-market race-block, he feels safe with EITHER bore/stroke combination.

 

I haven't tried a 406 or 377, but I definitely love my 388, it goes like stink.

 

I have been involved with all 3 combinations. Ranking as follows: 383=good cheap HP but don't plan to rev it much above 6,500 RPM for long term reliability (wears cylinders fast! at high RPM.) 377=rev happy engine good power/less torque than 383 if you spend bucks on cylinder heads (don't go too big on port volume, unless race application) and plan on running solid lifter cam (with it's associated high maintenance) needs good rods and proper assembly techniques for preventing bearing problems (unless you get exotic 400 journal crankshaft or trick race engine block to eliminate bearing spacer set-up with 400 production block.) 400=Ok motor, can be a relativley cheap build but stock rods are junk! and cause high cylinder wear, motor will use as much fuel as a big block and will not happily rev above 7,000 RPM (there is a good reason why sprint car racers almost always carry at least 1-2 spare 410 motors on "tour".) The 383 is probably the best "street runner" because it's long stroke gives great "bottom end" torque and the 350 engine block has better cooling properties than the "siamesed" 400 cylinder block. I am doing a hydraulic lifter 383 late 1pc rear main engine right now, should be 400+ real world HP with decent fuel mileage (18MPG) on highway, 12sec 1/4 miles in 72 roadster.

 

I agree with Solid LT-1 on most points but having built many of each combination I do not find some things true. All things being equal and properly set-up a 377 will make equal torque and more HP than a 383 just by virtue of the larger bore unshrouding the valves and making the motor breathe better. A large bore/short stroke motor is much easier to improve the volumetric efficency than a small bore/large stroke. Large bore/short stroke motors are much more touchy on camshaft selection. They generally need a much larger duration split to really use the benifits. They will also repond much better to inprovements in the cylinder head ports. I do not find that they want a smaller port, just a more effiecent port. The trend today to get the most HP/TQ per CI is to go small stroke/large bore. Even in drag racing the most common combination for the 500 inch pro stock motors are the DRCE2 blocks with a 4.900 bore spacing is to run a 4.700 bore with a 3.600 srtoke. that change is what lead to the last big jump in ET's.

A 377 does not have to turn high RPM to make power. As it has the same stroke as a 350 that would be like saying that a 350 has to turn 7000RPM to make power. But because it can breath easier it will not drop off as easily in high RPM as a 383 will.

But the down side is that to build a good big bore motor you need a good block and there just arn't many stock 400 blocks that don't have core shift and cam bore shift. So that requires an aftermarket block which puts the cost out of line for most street motors. For that reason alone a 383 is a better choice for an economical engine in a street car. Besides, most guys would rather be able to spin the tires than to keep the tires hooked and have the car accelerate fast.


[Modified by Pete79L82, 9:43 PM 1/26/2004]

 

the bigger the better. Pete makes some good points, but there is more to the picture. some people say siamesed cylinders are bad, not true!! cooling can be an issue if you don't use steam holes. other than that, the siam blocks are much stronger and more stable than conventional blocks. why do you think the C5R uses a siam block??? 400's have a bad rap from the old school wanna-be racers that never understood the full concept of the block. the 400 is still a treasure among those drag racers that understood and embraced the engine. 383's are cool, cheap and perform well. they are the quick fix to budget power building.
377's are different, destroked 400 that is (a 350 with stock bore and 400's 3.75" stroke is also a 377), they grab rpm very rapidly!! not much for tq vs. hp in 400 terms, but still very impressive. in a light car they are next to unbeatable. it is not what rpm they grab, but more of how fast they get it, is the correct way to look at them.
406's are bigger badder 383's. hands down they are more impressive. same stroke, bigger bore, same weight = better ET's and larger smile. now that in mind, couple of things to considder. STEAM HOLES! all 400 blocks need them. old blocks should not be verticaly 4-bolted, and they are hard to find. stock rods should never be used, try and use 6.0 inch rods or at least 5.7 inchers. most 400'sare snapped up by smart racers or trashed from missuse. about the core shift thing, some blocks should never be built for serious power. 400's or 350 blocks. good news, GM offers the 400 in a couple of different configurations!! regular splayed main iron, "rocket block" splayed iron, "rocket block" aluminum splayed main and also availible with dry or wet sump oiling systems. all are priority main oiling and except standard parts. iron blocks are $2400 ready to assemble, and aluminum range from $4000-$5200 depending on sale prices. big block guys are right in saying there is no replacement for displacement. where big cube small blocks shine is weight savings. it takes a lot of hp to overcome an extra 100 pounds. so find your balance line between power and weight.
side note. you can build the new GM rocket blocks to some serious cubes. it is easy to make a 454 small block. the wallet is the limit, not availible parts.
to answer one of your main questions, 406's don't have to rev to make big power. mine is 588 tq @ 4700 rpm and 606 hp @ 6100 rpm. those are on 88 octane pump gas and no assistence from forced induction or giggle gas. i will be glad to email you a dyno print if you want, just email and let me know. hope your engine building project goes great and you're totally satisfied with the results. Brian

 

You guys are pointing out a lot of the reasons I decided to go with my combo :D . My big bore short stroke is a 388 which puts me right between the 377 & 400. And yes this engine has a lot of expensive parts in it hoping for some reliablity ;)

 

Gary,
Sounds like a good subject for the club Tech. night somewhere in the future!
Bob