Calculating Distance Below Deck

[PontiacJim]

But let me ask you this: where do you think the torque and power peaks would be on a 500” engine set up as you describe with 245 degrees of duration?

I have an engine program, Dyno 2000, that I play with to see what engine combo's do what. Now this is not anything fancy as some of the more complex dyno programs are, but it is pretty good.

Here is what I put in using the 493 stroker as my base.
Stock heads with 2.080" Int/1.60" Ex done up with mild pocket porting (this should cover any minor head work)
Compression- 9.5
Intake - Dual Plane w/800CFM Carb.
Exhaust - Big cubes need to breath, so I inserted Large Tube Headers/Mufflers, which should cover a really good flowing exhaust set-up even if you don't go headers and use Hi-Po cast and some large Dia pipes.
Camshaft - Comp Cams XE274, Duration 280/286, Lift .488" Int/.491" Ex, LSA 110.
Here are the results:

RPM HP TQ
2000 196 513
2500 249 523
3000 298 521
3500 345 518
4000 380 499
4500 396 462
5000 388 407
5500 350 334

As you can see, great stump pulling torque numbers and it all falls away just over 5000 RPM's which is what you are looking for. I played around making a few changes and tried the next size up cam, XE284 and the High Lift HL275 cam. Power dropped. Tried a single plane intake, power dropped. I even inserted larger valves, "2.14 and 1.75" and power fell off.

I am no expert on Mopars, but knowing the CFM flow of your heads is important. You want to keep port velocity up for snappy throttle response and yet have enough flow to supply the bigger cubes at 5000 RPM's. I plugged in a few number into the Wallace HP Calculator which gives you an idea of the CFM's required to support "X" HP which is found here: Estimate Horsepower from Intake Airflow The highest HP numbers from my chart is 396 HP @ 4500 RPM's. 220 CFM's will support 417HP, but @ 4652 RPM's - which is short of your engine's potential of 5000 RPM's. So you need more flow. Now 240 CFM's puts you near to where you want supporting 455 HP up to 5075 RPM's. I personally would want to see a little more just to get slightly above my projected 5000 RPM limit. So lets go 250 CFM's which will support 474 HP and an RPM of 5286. Again, its not about the HP numbers you are looking at, but rather the CFM's needed to get the engine into the RPM you are shooting for - 5,000 RPM's. So what this shows you is that too little CFM's will not provide enough breathing potential for the bigs cubes and it will be your heads that limit the engine's RPM's. Go too big on the CFM's, and the lower end will suffer because port velocity will be sluggish until you get the RPM's up to get the intake flow/velocity up. But what good is that if the CFM's will allow you to spin 5500 RPM's and you build your engine for 5000? This is one of the ways an engine can be easily mismatched in its part selection - along with too big a cam.

Keep in mind that the intake also has a CFM flow that can affect things. You don't want a 250 CFM flowing head and use a 220 CFM flowing intake. You are going to kill the head flow. You want a dual plane intake for the street and I might select the Edelbrock RPM Performer for the 493.

So just a little insight that you might be able to work with. Take it all with a grain of salt. LOL

 

[NewportRbod]

Okay, you guys are reaching well beyond the little I know. I'm gonna go sit in my corner and be quiet.

Had to laugh. I think I'll just get a well engineered kit for a well trusted machinist to work with. I just have to figure out how to get it by my wife. She insists that having gas, electric, water, food, and shelter are valid expenses.

 

[Big_John]

Had to laugh. I think I'll just get a well engineered kit for a well trusted machinist to work with. I just have to figure out how to get it by my wife. She insists that having gas, electric, water, food, and shelter are valid expenses.

Remember that you can always sleep in your house, but you can't drive the house.

 

[PontiacJim]

Had to laugh. I think I'll just get a well engineered kit for a well trusted machinist to work with. I just have to figure out how to get it by my wife. She insists that having gas, electric, water, food, and shelter are valid expenses.

And that's why being single (and yes, I've been married and got the 4 kids to prove it) is the best thing in the world. I get to keep all the money I make, spend it any way I want or not, and don't have to ask permission or rationalize my reasonings to a spouse or a girlfriend - and NO Drama's, EVER. LOL I just buy the parts or cars and smile.