Are you joking b/c I cannot tell if you are serious or not.

If you are not, I am sorry, but I think you are getting bad information. A stock block may handle 800 for a little while on the strip before it splits, but not on the street. I would not put more than 400hp in a street stock block. It is a big gamble to same $1500. $1500 on a Dart, Ford Racing, or World block is good insurance if when you are putting $15-20k in a motor. It is your money, but you don't cry when you split your block and distroy your stroker.

As for 500hp out of a 408 stroker, get a dyno program to play with. If you do not, you will have no idea what the parts you are putting together are going to yield you. You may think your 408 should make 500hp, but really make 350.

IMO, to get 500hp out of a 408 stroker, you will need:
Forged crank
Forged rods
Forged pistons
4 bolt mains or main girtle
ARP everything
205-215cc intake runner heads with good flow
10:1 compression custom pistons
280-290 duration cam
750cfm carb
A nice single plane intake or tunnel ram setup which is probably going to force you into a scoop. (Dual plane or low riser intake will never get you there)

With all of that, DynoSim puts you at 491hp @6000 and 494ft*lbs @4500. The engine is not going to make 200hp until you hit 2500rpm, so you will want a manual tranny or high stall torque converter. Basically your peak horsepower will be dang near your redline which is not advantagous for performance. I am only 10-15hp off of that with my 383 peaking at 5500 and still have a 7000rpm redline. With my 383 I can use my good power above my peak before I hit redline which is where the performance is. With a 4.00 stroke and nice parts, your redline is going to be around 6200. If your peak horsepower is 6000, you will have an engine that cannot use its power. The optimum area for an engines performance is just before and about 800-1000rpm after the peak power. Run the numbers and you will see what I mean. That is why people use power adders to get above about 450hp because it ain't easy doing it naturally and still have room to use it.

 

Actual cylinder compression is altered by many, many things, like what Thumpin listed. Generally speaking, you can figure dynamic compression based on volumetric efficiency(affected by many of those things listed) and static compression. Compression*VE=actual compression(approximately). But, what that means is also like what Thumpin said, in a properly set up engine actual compression will be commensurate with static. Yeah, you might have low VE at low rpm, but then it will be higher at higher rpm, or vice versa. It comes down to where you're going to detonate, low or high rpm.

Too many people get hung up on trying to get all sorts of compression and then make it work, thinking they'll get power. Yeah, there may be people with iron headed engines that run at 11.5:1 on pump gas, but they're getting away with it because the engine's efficiency is way down all over the place, so they're losing all kinds of power as a result, just to make it work.

Generally speaking, most engines will make more power with lower compression and more timing and a better tune, than with higher compression, and having to pull timing and add fuel to prevent detonation, or run an overly large cam to decrease cylinder filling. Look at a NASCAR Busch engine.....358 cubic inches with a roller cam and a 390cfm carburetor, restricted to a maximum of 9.5:1 compression. They make a little over 500hp at around 6,500rpm. Compression ratio is no substitute for improved engine efficiency.

Also, pop-up pistons aren't all that great. Yeah, they may help raise compression, but the dome generally gets in the way of flame travel during combustion, so combustion itself becomes less efficient. That's why when you look at 2 nearly identical engines in terms of build with the same compression, the one with flat tops and a smaller chamber usually runs better than the one with pop-ups and a larger chamber.

 

Cool. someone else who understands. Not that the rest arent well on the way, or have achieved some impressive results, like the GT40 engine for example. One of the biggest factors is chamber shape, not only quench, but how the flame travels in it, where it originates, and also how the airflow works with the flame front. Its more than simple air in air out, a whole plethora of circumstances come into play.

Mostly I build Pontiacs, and due to the size of them they are more prone to detonation. There is a considerable difference between a 4" bore and a 4.12"-4.21" bore, so chamber shape makes a big difference in how much octane we need for them. They really dont like domes, we see a marked increase in fuel consumption with domes, and a poorer bsfc with them as a result. Aluminum heads with the right chamber shape will take almost two full points of compression over the late 60s closed chamber design with the same fuel. Aluminum transfers and dissipates heat far faster than iron does, that is why aluminum heads can withstand more compression, they simply run cooler.

But these arent Pontiacs, they are Fords, and actually they arent as different as you would think. Both are weak on cylinder head flow for the displacement, but they have high velocity ports (except for 4V Clevelands of course), and they tend to be more of a torque motor due to the somewhat longer intake port length. Regardless of how similar they are, or how different, there are limits to how much power you can make with a certain design at a certain rpm. Sure a 302 will rpm way up there, but still for the displacement it is more of a torque producer, and that is a good thing.

Airflow always trumps compression for power production. More air in means more oxygen available to burn, and you dont have to squeeze it so hard. That being said, efficiency goes up with compression, provided the fuel used is capable of not igniting before the spark is applied. If the fuel preignites then power is lost, trying to compress an already expanding gas will cost power if applied too early in the cycle.

Getting 600hp NA isnt easy. Sure it may seem like it when magazines are spouting big numbers like that, and claiming pump gas, but a dyno cell is very different from the engine bay of your car. The dyno cell removes most variables from the test and limits the amount of power drawn from other items in a vehicle, as well as giving the cell operator almost absolute control over engine temp and air temp. You dont have those luxuries in your car, plus you must drive the alternator, water pump, power steering pump, or whatever else its turning.

That being said, you either need huge torque to make 600hp or huge rpm. HP is a mathematical derivative of torque x rpm / 5252 rpm = hp. Torque is a direct measurement, whereas HP is that measurement over time. So above 5252 rpm HP is higher than torque, below that rpm HP is lower. So if your engine sustains or drops off less torque after 6000 rpm, you will get a higher hp number. That is achieved with longer duration cams, more airflow, shorter strokes, and intake runners tuned to operate at a higher RPM, such as a single plane or a tunnel ram. To make more torque, you can raise compression (while staying within the limits of your fuel), increase bore or stroke, or force air into the engine.

Increasing torque has its own effects on the reciprocating assembly as well as the block. RPM has similar and different effects than does torque. More rpm means that the pistons will be traveling faster, coming to a stop, and going back the other way far more often and violently. Rods break when the piston weight over stresses the rod and pops the beam near the top of the stroke. The block has design limits, and they have been found with the 302 and 351W, sure they can take 800hp a few times if prepped, but a standard block without girdles or studs will break far sooner with much less power applied to it.

For my engine to make 600+ hp, it took a 4.25" stroke, a 4.18" bore, heads that flow 310-330cfm, a cam with at least 260 degrees duration at .050 lift, that is like a 310 advertised duration, and around 10.5:1 with aluminum heads. Mine is similar to the sixth place Engine Masters Challenge Pontiac you can read about here. http://www.popularhotrodding.com/eng...emc/index.html
Except mine has more airflow, duration, and a solid roller cam rather than a solid.

Not bragging, just stating what it takes to make that much power at a reasonable rpm on pump gas. One of those engines will run you around $10k to build, and they need very good parts behind them, mine has broken everything except the differential and axles.

Why run the ragged edge of compression when you really dont need to and the gain will be minimal? Its just adding extra cost and complexity for a very small gain. its not just any single aspect of an engine that makes or breaks it, its everything about it.

 

That was very well said!