What good is a high rise manifold?

[devilgear]

I was checking out engines and such and was wondering what is the advantage of a high rise manifold? Does it make more power? Better airflow etc? I think they look cool popping out of the hood...

[Ghoste]

Oversimplifying, they make more power in a few ways; by having a larger plenum under the carb and therefore a larger fuel/air reserve available for the engine to use at WOT, by having (sometimes) larger and or smoother runners to the cylinders to let airflow in there easier, by having tuned length runners which take advantage of the pulses in airflow from valve events and using them to help "ram" the fuel mixture in.
This is basic and those do not necessarily apply in each intake but the basics lie in that and the plenum volume is arguably the one making the most impact.

[devilgear]

So is there a downside to them? I mean if  you had room in your hood? I was thinking if would be cool to put a blower on my car, but I can't afford that right now, but a cool high rise setup looks great as well...

[Ghoste]

There can be, the term "high rise" covers a lot of manifold ground so to accurately answer your question, what intake are you looking at and what is the rest of your build?  How do you intend to use the car?

[Foreman72]

There can be, the term "high rise" covers a lot of manifold ground so to accurately answer your question, what intake are you looking at and what is the rest of your build?  How do you intend to use the car?

indeed...i'm getting an eddy rpm air gap and that is considered hi rise..but i'm assuming you mean tunnel ram...something like this

[devilgear]

Yes Foreman pretty much just like that...Again I am just asking questions, so nothing but talk for now, but that picture would be it...

[Rolling_Thunder]

I have always heard tunnel rams blow for the street - something about having the fuel high up on the engine enduces fuel distribution problems ?   

[Ghoste]

That and that "ram tuning" effect I mentioned earlier.  Tunnel rams are typically tuned to be efficient at higher rpm's.  People use them on the street but in most cases make less power than a decent single four barrel dual plane; useable power anyway.  You also get the added headache in that case of tuning dual carburetors which is an art unto itself.  My advice would be to worry less about an intake just because it looks cool and get something that will make the car run stronger, you'll impress more of the real car guys that way. 

[mopar_nut_440_6]

I also like the look of the tunnel rams but maybe that is because I am old school! I used to run one on a 68 Charger with twin 625 cfm Carter carbs and it worked surprisingly well. It also ran 12.8 in the 1/4 @ 110 with an automatic and stock convertor with 4.56 gears. A bit of a dog off the line but a decent top end charge. Was very easy to tune due to the Carter carbs and super reliable. I eventually dumped it and installed a Holley SD and a Holley 750 DP which smartened things up. Tunnel rams are not as good as a single carb unless you are pulling big RPM but I still love the look of them.

Engine was a stock engine with 906 heads, stock valves, minor porting and a 509 DC cam. Nothing special.

[devilgear]

Ok all great info...I was just toying with the idea...I somehow knew something as radical as that would not be an easy thing to deal with....I still want a blower though..hahahaha

[375instroke]

You also need to think about what looks cooler--a tunnel ram in someone's rear view mirror, or your taillights pulling away.