[joswo1980]

Originally Posted by blownstang The new 5.0 has 11:1 compression and responds perfectly fine with a supercharger.

True, but op isnt asking how well it well respond, hes asking how well it well respond compared to nitrous, which really wouldn't be much difference, nitrous just performs very well with higher compression conditions compared to fi

[Eagle2000GT]

Originally Posted by blownstang The new 5.0 has 11:1 compression and responds perfectly fine with a supercharger.

From what I've read the new 5.0 has an oil cooling system for the pistons that our cars don't.

Nitmare, how do you calculate dynamic compression. I assume it has to do with the amount of boost and the compression ratio.

[stal94gt]

dynamic compression has to do with cams. you have your standard compression ratio that is made by size of combustion chamber and the size dish on the piston. depending on the grind of a cam the dynamic compression can be lowered or raised.

[Eagle2000GT]

OK. If your cams are venting out the exhaust port, then you will have less dynamic compression. Supercharger cams are not suppose to have much overlap. How that that figure in?

[Nitmare67]

Overlap isnt everything.... intake duration and closing points drastically change dynamic even with supercharger cams.... Search a dynamic compression calculator and run some numbers you will be amazed.

[Eagle2000GT]

OK. Its been a while but I thougt duration caused overlap.

[Nitmare67]

You need cam 101 man. Honestly cams are the most misunderstood part of engines for 99% of people. I spent years studying cams and profiles for SBF's. There are so many different dynamics at work that it will put you on over load if you try to learn it all at once lol.

Duration CAN affect overlap but depending on the lobe profiles, lobe seperation, etc theres alot more to it. You can have a cam with say 220/230@.050 with LESS overlap than a cam with 210/220@.050 and a smoother idle. You can also have a cam with more duration at .050 but less total advertised duration ( great for maintaining cylinder pressure) just by having a more aggresive lobe. Many companies dont even advertise their cams total duration anymore because all the values confuse consumers too much when trying to purchase a cam...... You notice Nick doesnt even have is total duration numbers on the website?..........CMS either, AFM and MPH wont even advertise their specs..... part because they're tying to be top secret and the other part because they would rather you pick by their descriptions of application and goals rather than try to compare numbers to find the better cam

[Eagle2000GT]

You are correct, lobe separation has a lot to do with it. But I don't really think its harder to understand than when we ran a single cam. Most of what I used to know, I've forgotten. Please remind me.

I'm not an expert by any means, but I kind of understood lift and duration back then. Except for the timing of the two cams, why is it different now.

[Nitmare67]

Its not any different. Basically everything is already set in the grind. I think you understand the basics of it but just not how much it really affects everything. A good excerise for you would be to head to comp cams (because they post all the specs) and check out a cam card for a particular grind and punch the numbers in a DC calc. Then get the numbers from a similar cams and run them.

I suggest comparing the xe262ah cam then the Supercharger version of the cam. You will be amazed at the difference in dynamic compression. Then compare both of those to a stock cam. The amount of boost you can run over stock cams with pump gas is a large increase. This is why i'm such an advocate for if you cant decide which cams you want... run the smaller one.. Once the dynamic compression dives off the motor is a total turd until it gets over its peak torque numbers then it may come alive or may not depending on cylinder head and intake design.

For instance. My 411W is 11.4:1 compression ratio... yes this is an old pushrod motor. I run Ed curtis AFR 205s and a large solid roller camshaft. I'm still able to run it on pump gas (91) octane and it makes peak power with 37 degrees timing in it with no detonation. I run 20 degrees initial timing. Most would say this combo is not possible but the DCR comes out to 9.25:1. Your limit on a pump gas N/A motor is between about 9.5 with a perfect motor. With proper quench (I run .038), chamber cooling, hot spots removed, piston coatings, great coolant temp numbers (never over 180 even on a 90 degree day. I have zero issues even on a 90 degree day. This particular car makes about 575hp.

Many people build a short block then choose a cam...... I choose the cam then build the motor for it. Its honestly the only way to do it right.