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compare 496 b & 499 rb

Posted By: 68roadrunner

compare 496 b & 499 rb - 12/16/11 02:29 AM

this being a race only piece. using same cam, heads, compression, everything. how would a 496 4.31x4.25 compare to a 499 4.375x4.15. i am sure the smaller bore would hurt flow some, but would have a lighter rotating weight. so what does everyone think?
Posted By: Bob_Coomer

Re: compare 496 b & 499 rb - 12/16/11 02:46 AM

Just curious what block your using for a 4.31 low deck build??
Unless these engines are all out 7500 rpm's id say there isnt much diff power wise, even then would be little measurable amount.
Posted By: 68roadrunner

Re: compare 496 b & 499 rb - 12/16/11 03:01 AM

383+.060 just thinking i got some parts laying around.

my 499 i turn 7000
Posted By: viperblue72

Re: compare 496 b & 499 rb - 12/16/11 04:38 AM

The rotating weight would be too negligible to matter. Bigger bore would help unshroud but would matter only a little. Id say the only difference that would matter is the 400 block is stronger and would be better that it isn't .060 over.
Posted By: 340_Dart

Re: compare 496 b & 499 rb - 12/16/11 07:59 PM

Quote:

The rotating weight would be too negligible to matter. Bigger bore would help unshroud but would matter only a little. Id say the only difference that would matter is the 400 block is stronger and would be better that it isn't .060 over.



Where is the 400 block in this post? i see either a 496 based off of a .060+ 383 block or a 499 based from a 440 block...

I agree though that i doubt you see any real difference in performance based on the 2 engines mentioned using the same top end components.
Posted By: StrokerAspen

Re: compare 496 b & 499 rb - 12/16/11 08:06 PM

Quote:


Where is the 400 block in this post?



For a big block stock block biuld, the 400 is my #1 choice...

-Kenny
Posted By: Cab_Burge

Re: compare 496 b & 499 rb - 12/16/11 08:08 PM

I like the 4.25 stroke with the BB Chevy rod sizes I have bought a 4.15 crank and had it offset ground to 4.300 stroke with the BB chevy rod journal size, 2.200 I also had the mains and counterbalnces ground down so I could put it in a 400 block, that made my 518 C.I. pump gas street motor
Posted By: dogdays

Re: compare 496 b & 499 rb - 12/16/11 08:55 PM

In general the RB has better intake manifolds available.

R.
Posted By: 440Jim

Re: compare 496 b & 499 rb - 12/16/11 08:58 PM

Attached is an estimate of the bobweights, rotating and reciprocating. The actual weights will depend on the exact parts, these are just estimates for the dia and lengths needed.

The lower bobweight will help a little, but only a little perf; the main benefit is lower stress and higher durability. With a good high flowing head, 2.2+inch intake valve, etc. the bigger bore will help fill the cylinders better making more power. Think 400 block rather than 383 or 440. Or just get a megablock...

Attached picture 6969824-BvsRB_bobweights.jpg
Posted By: moparacer

Re: compare 496 b & 499 rb - 12/16/11 09:25 PM

Quote:

Quote:


Where is the 400 block in this post?



For a big block stock block biuld, the 400 is my #1 choice...

-Kenny



X2 I buzz mine 7500

The bigger bore is a plus too.
Posted By: gregsdart

Re: compare 496 b & 499 rb - 12/16/11 09:43 PM


also go to the 440Source home page, and read up on blocks. It is an eye opener, and for a race piece, only a 400 block with either the best or second best web sizes above the main bearing saddles is good enough to put to use making race hp. The best combo to date is the 512, 4.375 bore x 4.25 stroke. Cheap, light, and big.
Posted By: Performance Only

Re: compare 496 b & 499 rb - 12/16/11 11:13 PM

the force is applied to the piston. the larger the piston, the more force is exerted on the crank. for the purpose of the engine combo's listed, bobweight has at best a negligble effect on actual horsepower.
keep adding port cross section and flow ability and the difference between the two combo's grows. limit port and flow and the difference is little at best. there's a lot more that could be added to this but all it would do is create confusion for the most part.
lighter rotating assemblies have the ability to make more power, but in many cases people tend to negate those gains because they make poor choices in other areas of the build,IMO.
Posted By: dmking

Re: compare 496 b & 499 rb - 12/17/11 12:27 AM

i my self found the 440 block made late with the same thick mains ans the wide supports under the jugs as the 400s (but not the monster thick ones) it has to be better than the stock 440 block. i am not leagle to go faster than 10.s so i just hope this one does not crack. some day i will do one of these combos.
Posted By: 68roadrunner

Re: compare 496 b & 499 rb - 12/17/11 03:29 AM

yes,yes,yes the block will break we all know that

if i had a 400 laying around i would be looking at that.(but i was not smart enough to buy any up)

maybe to make the rotating weight less, use alum rods. will alum rods fit in the 4.25 stroke 383?

it might not be a fair comparison but a comp eliminator motor makes good hp with small cubes. but does turn alot of rpm.

okay on
Posted By: polyspheric

Re: compare 496 b & 499 rb - 12/17/11 04:34 AM

The B has 2 minor advantages:
1. shorter cylinder wall = stronger and stiffer
2. shorter pushrods are much stiffer in the same diameter and wall thickness
Posted By: Performance Only

Re: compare 496 b & 499 rb - 12/17/11 05:29 AM

Quote:

The B has 2 minor advantages:
1. shorter cylinder wall = stronger and stiffer
2. shorter pushrods are much stiffer in the same diameter and wall thickness



if #1 is true, how come i consistently see the same amount of distortion in the cylinders of the low deck blocks as i see in the RB blocks when a honing plate is installed?

re; #2 buy stiffer pushrods for the taller engine if needed.
Posted By: dodgeboy11

Re: compare 496 b & 499 rb - 12/17/11 09:10 AM

Quote:

Quote:

The B has 2 minor advantages:
1. shorter cylinder wall = stronger and stiffer
2. shorter pushrods are much stiffer in the same diameter and wall thickness



if #1 is true, how come i consistently see the same amount of distortion in the cylinders of the low deck blocks as i see in the RB blocks when a honing plate is installed?

re; #2 buy stiffer pushrods for the taller engine if needed.



#1 because the deck's are the same so the distortion you see is the same. But, the length of the cylinder is shorter so the strength of the cylinder will be stronger, thickness being equal between the two blocks.

I agree with your response to #2.

But, to continue, the 383/400 block is stronger downstairs due to the smaller main housing bore as well as it being a slightly more compact setup because of the shorter deck. The lower rod ratio will increase the bottom end and the added stroke will offset the smaller bore difference. BUT you can get a super victor intake for a 440 with a dominator flange that you can't get for a B deck block. Some builders feel it gains more to add a spacer/adapter to get a dominator to fit though so I'm not really sure of the real advantages of this.
To put it in a different perspective, I have dyno'd both combos with similar heads and cam specs. They both made right around 570 hp on pump 91. The RB had an eagle crank that hit the bottoms of the pistons with the counterweights (I really don't like eagle crankshafts). I had to grind a bunch more material out of the RB because of the larger rod journals too. I don't care if you want the RB block, go with the 2.2 journals and save some headaches. For that matter, run the 4.375 stroke and get 520ish inches.
To sum it up, if you have a 383 block, build the 496. 440, go 493 (.030 440). If you have both, decide which one is better based on a packaging standpoint: weight, clearance, etc...
Posted By: polyspheric

Re: compare 496 b & 499 rb - 12/17/11 03:11 PM

buy stiffer pushrods for the taller engine if needed

Wow, thanks, you're the first one who thought of that.
Posted By: 68roadrunner

Re: compare 496 b & 499 rb - 12/17/11 03:28 PM


The lower rod ratio will increase the bottom end and the added stroke will offset the smaller bore difference.

that is what i was getting at. so you are saying the extra stroke 4.250 over 4.150 will help overcome the bore difference of .065 .

would a different cam and head port size help the smaller bore fill better. would you use a smaller faster port or not
Posted By: Performance Only

Re: compare 496 b & 499 rb - 12/17/11 07:54 PM

Quote:

buy stiffer pushrods for the taller engine if needed

Wow, thanks, you're the first one who thought of that.



right, the only problem here, other than your sarcastic attitude, is that you make it sound like the extra 3/4" is a really big deal. it's not. given the same spring pressures in either scenario, the same thickness pushrod would work in either.
your great with the math, but i get the feeling you have very little practical hands on experience with this stuff.

as far as the cylinder walls being stronger because they're shorter, that's more myth than fact. we aren't talking about a machined tube here, it's a cast iron cylinder wall with imperfections all over the outside cast wall.thick and thin area's exist in both B and RB blocks. if you have a thin wall in the middle of the B block cylinder, it's a weak area just like it is in a RB cylinder. the only true advantage to the B block is the stronger bottom end.
in the 35 years i've been building these engines i've yet to see more than a handful that actually had thick symmetrical bores on all 8 cylinders. if you could actually find one, then i'd say THAT particular block would be stronger. we don't work in the theoretical world though.
in response to the block distortion from a cylinder head or honing plate, there's no difference in the strength there either. the deck is connected to the cylinder walls. if you torque the fasteners on either block they both distort the same amount. if the cylinders were stronger in one vs. the other, that wouldn't happen. the distortion shows up in the bore as well as the deck.
Posted By: Streetwize

Re: compare 496 b & 499 rb - 12/17/11 11:31 PM

The low deck is roughly 7% shorter so as Dan said it's not really as significant as some think. However the rotating mass is that much ccloser to the crank and the low deck will have a lower center of gravity all else being equal.

any block is only as strong as it's thinnest bore.

Thew main advantage to the low deck ( to me) is they used to be cheap to find and the smaller journals on both the rods and mains (when you go 2.200) just helps the bottom end spin a little easier. and generally lighter is (if little more) extra insurance for when you over-rev. Headflow, cam and compression pretty much determine the sweet spot and the rev cieling, lighter bottom ends just get there a little easier and are 'less brutal' to themselves at thigh rpm.

Expert machining is the key to a great running motor, Typically experienced builders can tell how well a motor will run by the way it falls together, and also how well (or poorly) it ran by how it comes apart.
Posted By: d-150

Re: compare 496 b & 499 rb - 12/18/11 03:07 AM

best advantage is the b block gives a little more room under the hood. i think 440 get a bad rap for cracking. if you have 2 million 440 blocks compared to 3 hundred thousand 400 blocks your probably going to see more cracked 440s
Posted By: 68roadrunner

Re: compare 496 b & 499 rb - 12/18/11 04:19 AM

fftopic


this post was supposed to be about the performance difference between a 4.31x4.25 stroke compared to a4.375x4.150 stroke.
Posted By: Performance Only

Re: compare 496 b & 499 rb - 12/18/11 10:03 AM

Quote:

this being a race only piece. using same cam, heads, compression, everything. how would a 496 4.31x4.25 compare to a 499 4.375x4.15. i am sure the smaller bore would hurt flow some, but would have a lighter rotating weight. so what does everyone think?



the way the question is worded makes it pretty generic. your not offering any specifics for the build regarding the heads, cam, compression, intake manifold, etc. etc. or for the car it would go in. if this is a build your actually considering, the answers would be better if you added some information.
Posted By: gregsdart

Re: compare 496 b & 499 rb - 12/18/11 12:30 PM

Quote:


The lower rod ratio will increase the bottom end and the added stroke will offset the smaller bore difference.

that is what i was getting at. so you are saying the extra stroke 4.250 over 4.150 will help overcome the bore difference of .065 .

would a different cam and head port size help the smaller bore fill better. would you use a smaller faster port or not

The ports you use will determine total output in torque and hp. The bigger bore will help airflow some. The rod ratio differences may or may not make a difference, and a lot better minds than mine disagree on that subject. Read the tech pages on the Reher Morrison web site. From my perspective the reasons to go with one over the other is based on bore size, and ultimately on how hard I am going to push to blocks. The 383 Vs the 440 is kind of an unknown when you look at their bottom end strength, and the difference may not be that much based on the info on the 440 source page on blocks. Neither is a good candidate for power over somewhere north of 650 hp.
Posted By: coronetville

Re: compare 496 b & 499 rb - 12/18/11 03:29 PM

I think the this topic started with using a .60 over 383 block and a 440 block, that he had. the 400 block wasnt the in the question
Posted By: 68roadrunner

Re: compare 496 b & 499 rb - 12/18/11 04:15 PM

Quote:

Quote:

this being a race only piece. using same cam, heads, compression, everything. how would a 496 4.31x4.25 compare to a 499 4.375x4.15. i am sure the smaller bore would hurt flow some, but would have a lighter rotating weight. so what does everyone think?



the way the question is worded makes it pretty generic. your not offering any specifics for the build regarding the heads, cam, compression, intake manifold, etc. etc. or for the car it would go in. if this is a build your actually considering, the answers would be better if you added some information.




okay, 13-1 compression flattop zero deck,284 288 680 lift lsa 108, -1 heads 2.19&1.81 325cc cnc port flow 355 or so, dominater on alky

i know how this runs in a 440 block with a 4.150&4.375 how would this run in a 383 with 4.31x4.25 stroke
Posted By: gregsdart

Re: compare 496 b & 499 rb - 12/18/11 04:15 PM

Quote:

I think the this topic started with using a .60 over 383 block and a 440 block, that he had. the 400 block wasnt the in the question

Thats why my last post says what it says. All posts so far have tried to provide help, and a lot of us believe the right direction is to bail on the 383 and 440 block and go 400. But that is up to the OP and what he intends to do with the combo. If it is a low power bracket combo, and a few hp lost to the small bore is of no concern, he may chose to go that way (383) and it would be fine. Ditto on the 440 block if the cylinder walls check out better and it makes a better low hp bracket motor, the choice may be the 440.
Posted By: dmking

Re: compare 496 b & 499 rb - 12/18/11 06:15 PM

well i would go with the 440 block over the 383 and stay under 680hp. the 383 looks weaker than the 440 botom end with the middle mains even smaller than the small older 440s.

i just took apart a nother 6630-440 block with .520 middle mains. those are real close to the good 400block thickness by .030 but not the hard to fine super block 440source talks about 400 wise anyway.

someone around my area says "my engine builder says" the 383 block is a stronger setup over a 440. well one would not know that just looking at it and mesuring things. and i am now gun shy since i split my 73 440 block.
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