This thing has me baffled. They designed a beautiful high flow eight barrel intake and then stick a two barrel throttle body on it. Why? Wouldn't they get a lot more flow if they stuck two four barrels on it?

Then you could connect the linkage however you want, to get good part throttle response/economy out of two barrels or whatever. And when all eight barrels open up, you know you got something.

 

I was asked?"will the steath ram flow enough air to make max power"
well lets do the math,
the steath ram is designed for the sbc engine, the largest normally built sbc displacement is the 434cid engine. the 434 engine spinning 7000rpm (thats well over the normall rpm for that engine even in race form) can use about 880cfm at 100% efficiency. the steath ram is cut to fit a 58-60mm twin throttle body bore size. that bore size flows about 1000cfm, well above the level thats necessary to feed even that larger than normal displacement.
now holley says that the ports in the steath ram flow about 300cfm
and several people have flowed the intake and thats true, but keep in mind that flow benches measure steady state flow, also keep in mind that the 4 cycle engine has a total of 720 degs in the total repetitive cycle and only about 250 (THE CAMS INTAKE DURRATION) of those 720 degrees are used to flow air into the cylinders on the intake stroke and if you carefully take the time to measure youll find that about 85% of that 250 degrees is flowing a usefull amount of airflow for a total of about 259cfm at a time per cycle trying to move into a single cylinder. now since the cylinder on a 434 spinning 7000rpm only needs 110 cfm even at a steady state flow into the cylinder and the cylinder can only hold that aproximate 110cfm the intake (steath ram) flows more than enough air to make max power , and more than enough air to to feed the largest flowing heads that normally fit the steathrams intake ports (like the 195cc AFR cnc heads)

_______

keep the rubber side down and the fiberglass off the guard rails

 

Makes sense to me.

So the throttle body is not too small. The manifold is too big.

I guess the appropriate question is, "what's the advantage of making a manifold that will flow 259 cfm per runner when you can't need more than 110?"

 

Homer
the manifold is exactly the correct size! remember that each runner is a column of air and that air has volume, weight and energy. now its true that the cylinder can only take 110cfm BUT remember that during of all the time the engine is running is in a 720 degree repetitive cycle? and the air can only flow into the cylinder durring the 250 degrees or so that the valve is held open by the cam? well that means that the air flow needed is 720 degs/250 degrees x 110=316cfm or just about what the intake port on the stealth ram can flow at max volume. or put another way youll need to push 316cfm down the port because its only open durring 34.7% of the time available to fill that cylinder

 

Ok, now I finally get it. The lightbulb went off, and it all makes sense. Thank you so much.

I guess my only question left is, if this is the ultimate manifold, where do we go from here?

Later,
Homer

 

Racing!

 

theres ALWAYS ROOM FOR IMPROVEMENTS IN ANY SYSTEM

 

Turbo, man. Turbo.

 

I know there is always room for improvement. But from what I'm hearing, I don't see where it could be. The stealth ram flows "enough air for max power." Once you have "max power," what else is there?

Then again, how do you know you've reached the max?
Homer
P.S. Damn, I wish I could afford one of these.

 

There is no "max power". It all depends on how you design your motor, but you have to realize that there is a compromise. To increase power, you need a bigger cam, better heads, etc. More air in, more air out. The problem is, as you increase your potential for airflow, you sacrifice drivability and low rpm performance. There is no "maximum". It's just all about where you draw the line of compromise. With enough $$$ and talent you can build a 2,000 horsepower small block, but I can guarantee that it won't be a fun ride to the grocery store in a car that idles at 2,500 rpm, creates more heat than the sun, and takes 5 gallons of methanol for every mile you drive.

Since you're a "newbie", I would suggest buying one of the 10,000 books in the Automotive section of your favorite book store and start trying to understand how things work. Magazines can be a great place to learn too. Most of the magazines out there like CHP, Super Chevy, Hot Rod and especially Car Craft have a lot of technical articles that do a good job of explaining what's going on.

 

--------------------------------------------------------------------------------
buy these FIVE books, it will be the best money you ever spent, read them, and you will be miles ahead of the average guy.
HOW TO BUILD THE SMALL BLOCK CHEVEROLET by LARRY ATHERTON&LARRY SCHREIB
.
HOW TO BUILD MAX PERFORMANCE CHEVY SMALL BLOCKS ON A BUDGET by DAVID VIZARD
.
JOHN LINGENFELTER on modifying small-block chevy engines

how to build & modify CHEVROLET small-block V-8 CAMSHAFTS & VALVTRAINS BY DAVID VIZARD

SMOKEY YUNICK,S POWER SECRETS

 

John Lingenfelter: On modifying small block chevy engines<----

 

Thanks for the book recommendations. That's not a bad list you guys put together.

I understand getting the right size manifold for your application. That's why I got confused when it was claimed that the stealth ram is the right size "for max power."

If it's sized for max power on a 7000 RPM 434, isn't it oversized for anything else?

 

no, its sized to meet the max flow potential thats likely to be needed but the LENGTH of the runners from the back of the intake valve to the plenum plus the effective size and length of the primary pipes on the headers, the engines cpr and displacement and the cam timeing determines the rpm range that efficient cylinder scavageing takes place, the TPI system has intake runners about 21" total in length and is effective in the 1500rpm-3500rpm range, the super ram has runners about 17" long makeing it effective in the 3000rpm-5000rpm range, the stealth ram has about 10" total runner length makeing it effective in the 4500rpm-6500rpm range (right were max power with most sbc engines is normally found) the mini rams shorter runners place its effective range partly above the rpm range a l98 engine will ever get into. look at it this way, the pressure waves that make a tuned intake work are moveing at a more or less set speed up and down the runners at any given rpm, the size of the runners effects this thats true but most of the intakes mentioned are similar in size as to the intake ports as the intakes match the chevy cylinder heads but the length, varies this makes the returning pressure waves and restrictions in the port vary with the length. here read this

http://www.grapeaperacing.com/GrapeA...ehelmholtz.cfm

http://www.engr.colostate.edu/~allan...ngth/pipe.html


but keep in mind that the rpm ranges its discussing are a little higher than whats involved due to the port sizes, and that there are first, second, and third and fourth order reflective pressure waves effecting the ram tuneing the fourth order wave is whats normally used.heres what my computer says
Computation Results:
Input length is 10 inches
For 2nd harmonic, RPM range is from 9790 to 11880 with a pulse strength of 10 percent
For 3rd harmonic, RPM range is from 7356 to 8407 with a pulse strength of 7 percent
For 4th harmonic, RPM range is from 5735 to 6413 with a pulse strength of 4 percent

the first through third order waves normally would require an intake to large to fit under a cars hood, and keep in mind that prediction is for the PEAK effective level, not the total effective level

 

So the actual displacement is irrelevant unless it outflows the manifold?

a 283 that peaks in the 4500 - 6500 rpm range would be best served by a stealth ram, correct?

 

displacement has an effect but the efficiency of the exhaust scavageing and the intake runner length, compression ratio, cam timeing, etc also have an effect. short answer , yes a 283 would still work well with the steath ram but its lower total displacement would tend to raise the rpm level of the intakes effective range, but yes in a very broad sence your correct

("So the actual displacement is irrelevant unless it outflows the manifold? ")

, thats why the performer rpm (almost the standard performance sbc intake) still works ok on the 265-400 chevy but its larger ports tend to flow more than enough air for anything under 327 cid and restrict the high rpm breathing on the 400 chevy, the port length is correct for the average sbc but the cylinders displacement and port volume also has an effect on how well it works.and as the engine displacement increases the rpm range that its effective in tends to decrease yet the port length still works
everything in an engine is a compromise, yet some designs are far better than others at effectively meeting the goals