i know that they are torque monsters, but can they rev up quickly for blazing acceleration? are there any aftermaket parts for that beast? Thanks!

 

They don't rev all that quick because of the longer stroke. The 427 rev's like crazy, but it's down on torque in comparrison to the 502. Their claim to fame is torque, but it's no slouch in the rev department either.

As far as aftermarket parts, yes. All a 502 basicly is a bored and stroke 427/454. :cheers:


[Modified by Corey 68, 1:47 AM 10/5/2002]

 

Cutting weight on the reciprocating assembly and leaving the rotating mass alone improves revving substantially.

 

That and a aluminum flywheel. :yesnod:

 

does the 502 rev quick? U bet it does? Want it to rev quick? Get an internally balanced crank, and the 427 harmonic balancer, and you're in business. Oh yea, can the 7/16" rods and get a good set of Hbeam's that are good for 800HP, 3/8" and lighter

 

thanks

 

wait a sec... i was under the impression that the 502 was a slightly diffrent block than the 396/409/427/454... was i lied to?

 

It is different in that it has Siamese cylinder walls.

 

i see, i see... umm whats that? :lol:

 

prowler, the way it was explained to me, is that a block normally the cylinders are offset slightly, well on the 502, or 400 sb you have the center point of the cylinder even. Then they are SO STINKIN CLOSE to the water jackets, that its a marvel they stay in one piece.

The 400's like to overheat from what most guys tell me, but i haven't heard anything about the 502. Any of you guys want to offer some first hand experience on this?'

Hope that explained it...
ZD

 

I have a early style 502 450 HP It has steel square port heads It is different in that it has Siamese cylinder walls thats how they get the big bore Its uses a forged 454 crank
I bought a OLD 72 nova Race car with glass nose and doors Dana 60
car # 2950 with the big block I am running a powerglide with a trans brake
The car has 513 :crazy: gears in it now and let me tell you they rev fine
I need to change the gears before I take it to the drag strip and the motor runs very cool with a cam change and some port work these motor have made over 600HP and then theirs NOS :cheers:

 

On a siamesed cylinder block the cylinder wall is touching the cylinder wall next to it at the 3:00 and 9:00 position. This eliminated the water jacket between the bores allowing for a larger bore.



(exaggerated for clarity)

A siamesed cylinder block should be no harder to cool provided that wall thickness on the remaining bore is sufficent to eliminate bore distortion.

A 502 is the same stroke (4.00") as a 454 but has a larger bore (502 - 4.470" vs 454 - 4.250")

All things being equal a 502 would accelerate the same as a 454 because all the internal components are the same (except piston bore) , but because of the increased cubic inch and increased horsepower it will allow the 502 to accelerate quicker than a 454.

 

I think what you mean to say is that the 502, having the same crank as a 454, would rev the same as the 454, but the increased power (all else being the same) would make it accelerate quicker than the 454.

Keep in mind that I said "all else being the same". A built 396, 427, or 454 could still out-accelerate a mild 502. The increased cubic inches do not automatically make it a quicker car. It does, however make it POTENTIALLY a quicker car. With more cubes to work with, more power can be had with the same upgrades.

The siamesed cylinder walls can pose a problem on a 400 small block if short rods are used, which increase cylinder side loading dramatically. They tend to crack. They'll also crack if allowed to overheat sometimes. You have to definitely increase the rod length on a 400 block and have a stout enough cooling system to control heat. Have a 400 block magnafluxed to make sure there is no cracking.

When Chevy increased the stroke of the 427 in 1970, some of the engineers disagreed with the move. Sure it increased bottom end torque, but it also raised durability concerns. With modern metallurgical technology, those concerns are probably nil, with cautious observance of a lower redline. The 454 was found to not make any additional power over the 427, when both were built up. They both had close to 600 hp potential in those days, when ultimately built up. I think racers preferred the faster revving 427's.

Other than that, a 502 should be fine. Huge torque in a package no bigger than a 396 basically. Just observe the same redline that a 454 would typically have. That's around 5600 rpm nonforged, and 6000 rpm forged.

My Pontiac 455 makes similar torque to a 502, but without the rev-capability. They're definitely done by 5500 rpm. But ya know what? With all that torque, on a street car, you don't miss the rpm's either!!!

 

Are you referring to HP, TQ, or BOTH?? A built 427 and 454 will make the same hp, but the 454 will put out a higher tq number no question.
Cubic inches = torque. I

In the 60's the 427 was the way to go as for as rev's are concerned. But this day and age you an get a 454 or 502 to rev just as quick as the shorter stroke 427.
:cheers:

 

Actually, if both engines made the same hp at a given rpm, they would also make the same torque. Hp and torque are not two separate things. Hp is a measurement of torque at a given rpm. If an engine makes 400 ft lbs of torque at 4,000 rpm, it will also be making 304.65 hp at the same time. If an engine is making 500 hp at 6,000 rpm, it will be putting out 437.67 ft lbs of torque at the same time. Increase or decrease the torque or the rpm and the hp goes up or down in proportion.

ith everything else being equal, more displacement will result in more torque and it will also make it's peak torque at a lower rpm. When you feel the extra torque of a larger engine, you are feeling the effects of it making more hp and at a lower rpm. That in turn allows it to rev quicker to a higher rpm and even more power. An example of this would be two 300 hp engines. One has 350 cubes and makes it's 300 hp at 5,000 rpm and the other would be a 200" engine that makes it's 300 hp at 7,000 rpm. If in otherwise identical cars, the car with bigger engine would accellerate quicker despite it's heavier internals. This is because the larger engine's greater hp at lower rpms allows it to overcome the resistance of the car sooner than the smaller engine, therefore reaching it's peak power sooner. While both engines would be making the same power once they reached their peaks, the larger engine would reach it's peak sooner.

 

i know light weight internal parts and flywheel makes it revv faster too. not as much as a smaller stroke but it helps.

i also know hondas (i know i said the h-word :eek: ) revv to 9 grand because of thier amazingly short stroke, and large cylinder bore. just something to ponder.

 

With everthing else being equal, a lighter reciprocating assembly will rev quicker, helping the engine to get to higher rpms quicker. At the same time though, less mass will have less stored (kinetic) energy to overcome the resistance to accelleration of the engine itself and also the resistance of the vehicle it powers. There's a tradeoff between heavier vs lighter flywheels and, except for dedicated race cars that can benefit from one or the other, a compromise is usually desirable. Drag racers running small cube engines sometimes use a heavier than stock flywheel in order to take advantage of it's greater mass which provides more stored energy for the launch. Even though the car's accelleration rate beyond the launch is reduced, the heavier flywheel's greater intertia at launch gave enough of a "head start" to more than compensate. Keep in mind that I'm talking about cars with suspensions and slicks that can take advantage of a harder launch.

The effect of a lighter rotating assembly is much like a larger cam's. Even though power might be increased, power delivery will seem "softer". While low end torque is unaffected, a lighter rotating assembly won't feel as torquey. I once tried out an aluminum flywheel on a 396 Chevelle. With 4.10 gears and too little traction, it's softer launch and quicker revving improved my et's by over a full tenth. On the street though, I was spending more time slipping the clutch during normal take offs and I also noticed more surging and other engine activities than with the heavier flywheel.

I don't think Honda's, or many other small engines, have a short stroke, large bore relationship. Last time I looked, they were actually closer to being "square", meaning that their stroke was close to their bores in dimension. While from a performance standpoint, a shorter piston travel and a larger valve area (allowed by a larger bore) are very desirable. In a production engine that also has to produce the least amount of emissions, the highest possible fuel economy, and be as compact as possible for styling purposes (and, again, aid fuel economy by allowing better aerodynamics), long stroke to bore ratios are now common. While the strokes of these little engines may seem large in relation to their small bores, typically, they are still much smaller than many BB's (and not just Chevies) that have been known to rev well past 7,000 rpm and do so with some reliability.

 

If any of you are contemplating getting a 502, forget the short block....build your own. I purchased the bare block, timing cover, pan. Purchased the 4.25" stroke, internally balanced crank, used my 427 harmonic balancer, got lighter h beam rods.

The price is the same on the cranks...regardless of the stroke, same on the rods, same price regardless of rod length, so, for the price of $00.00, i got 31 more cubes...oh yea, the pistons, SRP (JE), same price.

What did I end up with? A 533 cube that revs like a 427, and yea, 7k rev? Like a walk in the park, no effort.

 

is the block on the GMPP catalog? and is your crank forged?

 

u bet, 4340 steel