Air cleaner, scoop, velocity stack form vs. function

[Bugflipper]

Well folks I'm in a quandary. I'm wanting something that looks good to me and also performs good. Motor is a 5800 rpm sbc with a street demon 625. Everything I have read says a scoop screws things up and is acceptable backwards but a turd forward. Another issue is the teeny tiny 6" filter in them. If 14x3 is the minimum for not loosing power, how can a little 6" supply what is needed? Been trying to read up on velocity stacks but it seems the new fuel injected ones eat up all the search engine can provide. Haven't been able to locate any info on the old velocity stacks they ran in the 60's.

So I'm pretty well all mixed up. I like the hilborn and double barrel scoops the best, just to look at. Next would be a velocity stack and finally an air filter. Don't really care what folks seeing it think about it, just my prospective while driving is what I mean by looks. Please educate me on these scoops as to if they are enough air for the motor and your outlook on the general subject of filtration please.

 

[bobs66440]

I'm going to use a scoop...I think...but I'm just running a stock 350...

 

[Mike]

On filter selection, the bigger, the better. And stick with paper filters, because no matter what the oiled gauze people try to tell you, particulate matter in the oil will always be lower with paper.

If you are looking to maximize power, use a K&N Stubstack inside a 14 air cleaner. Find the tallest paper filter you can find and run it. Mind, the Stubstack will eat up some vertical space inside the air cleaner, so you are going to want a tall filter.

 

[Oldbuilder]

Okay I'll jump in here and show my ignorance ha ha ha . The issue with running a stack facing forward into the breeze is it forces air into the carb,,,, not good,,, a carb uses pressure drop to work,,, not a pressure increase,,,, fuel injection benefits more form forced air. You can run stacks but you'll have to tinker with finding the just right angle,,,, the key is getting the air flow past the inlet not to be pressure or vacuum. You'll either run really rich or really lean. I want to go with stacks too so this will be an experiment in the future. I think they look really cool on the Tri-Power setups,,,, anyone who's done this before please jump in with your wisdom.


MERRY CHRISTMAS YA'LL from Texas

 

[TriodeLuvr]

If you want to discuss the performance issues of these various devices, you first have to specify vehicle speed. Most of these intake designs do little or nothing until you reach twice the legal limit.

Jack

 

[Bugflipper]

I've always wondered about those stub stacks. Can't run one with what I got though. No drop base cleaner either. http://www.demoncarbs.com/1904.asp

As for speed that's a bit unfair because most of us here cruise at the speed limit. But in all out romps can be near or over 3x the legal limit. If you can get one to hook up 1/4 mile speeds can be in the 140's with a normal street engine. So I guess it would be better to discuss wide open throttle at speed as well since no one wants to limit their potential. But honestly if we drove wide open all the time I doubt we'd live long.

 

[Mike]

As for speed that's a bit unfair because most of us here cruise at the speed limit.

Which I think was rather the point being made.

First of all, I want to say I always encourage everyone to drive at posted speed limits. If you want to race, there are places designed for that specific purpose.

Beyond that, I think what TriodeLuvr was trying to say is there are things that can make significant power improvements and there are things that can make significant power improvements at extremely high RPM. When it comes right down to it, at 35 MPH, you are going to fool only yourself by thinking that one air cleaner is better or worse than another. Or that a scoop will out-perform an air cleaner. It simply does not matter. It's a bit like the guy who buys the roller rocker arms for his hydraulic-cammed motor, because they will 'reduce friction'. Aye, and tell me how much of that you felt in the seat of your pants, the first time you pulled away from a stoplight. Roller rocker arms were made to withstand the loads of racing valve springs, not to free up some infinitesimal amount of frictional loss.

The same goes with whatever kind of lid you want to put over your carburetor. At your average cruise speed and cruise RPM (do you realize how low those numbers really are?), things just don't come into play as you would hope they might. It is a fact that anything you can do to straighten out air flow at the throat of the carburetor will let the carb do a better job of metering fuel. Is that as critical at 30 MPH as it is at 180 MPH? Absolutely not.

If you have ever spent any time near an engine dyno, think about how many of those engines you witnessed being run with the same headers that were going to be used in the car. How many of those engines were being run with the same air cleaner/scoop combinations that were going to be used in the car?

The bottom line is that you should go with whatever components appeal to your eye and try not to fuss too much over 2 or 3 HP, here and there. I promise you, the standard T chassis is going to lose a lot more power than that, so you would never feel the difference. Sure, there is not a Pro Stock team out there that wouldn't sell their collective souls to find 3 HP, but when you have a chassis that is that well-designed, then the additional power will generally arrive at the rear wheels. But then again, if you could see what some of those teams are paying for rear shocks, you would have a coronary. I can quite confidently state the low budget teams have more in a pair of shocks that you have in your entire T-Bucket.

Find something that appeals to you. Something you can easily afford. Bolt it on. And then, enjoy it. Because in the end, as long as you are content, nothing else really matters.

 

[bobs66440]

I agree.Besides, considering the power to weight ratio of these cars, it'll be fast regardless.

 

[bigblk1177]

Sounds like the old K.I.S.S. principal again!!!

 

[Screaming Metal]

Like Mike says, more or less that Air cleaner has to flow at LEAST with those pistons and valves going .... but for cruisin' the speed limit.... and not trying to hit the high side of the rpm range going thru the traps....its best to stick with looks. Hell...25 to 50 horses ain't gonna make that big of a deal for a cruiser since a 305 can push these cars into a uncontrollable situation.

The Velocity stacks that were run on the old 97's and such back in the old days, those motors didn't make alot of horses stock, so it was trying to go as fast as you could on the least amount of money. Thats the reason for the really big performance motors in the light cars, getting the power-to-weight ratio on up there. Most didn't have air filtering period....all kinds of crap was injested by the motors. I've found all sorts of crap stuck on top of those pistons and bent valves because something get stuck between the valve and the seat. Seen many 'flameouts' due to pieces of rag, paper, trash, plastic....

Performance wise and good looks, comes from the Large 4 bbl velocitky stacks, with the cheap foam filter that lays in the top, replaced. One of my favorite things is to get a filter the sits down about 2/3rds of the way into the stack, sit several of these filters one on top of the other, with the very top filter just barely sitting above the edge. More filtered air is flowed this way. Forward facing scoops is fine in a tuned Gasser thats going 150+ or a really good performance setup that spends the majority of its time in the higher rpm range the majority of its life. What your looking for is surface area on your element. The more area you have the more flow you have. More flow= more performance

Look thru all the old books and look at car shows, find something you like and build it. Like Mike said, the big name teams run motors on the dynos in long sessions, trying to find those 2- 3 horses. I've seen as much as 30-40 hours placed on 2 or 3 'mule' motors, trying to find those horses....
Hell, I've seen 100 hr. sessions on flow benches with just hood scoop data being collected.

 

[Screaming Metal]

Let me also caution you when you sit these 2 or 3 aircleaners one on top of each other, silicon them together and sit a weight on the top of them, before installation to help seal them. Also, just above the area where the bottom of the filter element sits, drill several small holes to drain off water just in case of rain, and as dirt and dust settle, you can lightly blow things out before you remove them and find all kinds of trash falling into your motor.
I put some dykem or persain bluing on the bottom edge of the the air cleaner, to mark where to put the lower Brackets for the cleaner to sit on. Then I either tack or bolt several brackets inside for the filter to pull down agianst. Just make doubly sure things won't come loose and fall down into your carb....

 

[Rogers23T]

Ok here's my 2 cents; first I want to say the K&N air filter that allows the engine to pull air from the top as well as the surrounding band would be great but doesn't have that hotrod flair. The scoop will increase air flow into a normal aspirated engine. This will cause the engine to run "lean" to correct this you must increase fuel to maintain a proper fuel/air ratio. However you will find using that scoop, engine tuning will be quite tedious. Now as we all should know the basic rule for making HP is you need to stuff as much fuel/air as possible and as fast you can and get it out as fast as you can. So the scoop can make you more HP at higher speeds. And just like using a roller rocker on a hyd cam. every little bit can help in making HP. I have ran roller rockers on a hyd cam, and found the engine made a bit more power due to the increase of 500RPM's changing power curve a bit, and the engine sounded like it rev'd quicker. And let's face it ANY reduced friction is a plus no matter how small when it comes to making more HP. I say no matter if it's for looks or power ... It's hotrodding and that makes it your special project and you should build what you like.