[grandville455]

I have a cowl scoop on my car about 3" tall and pretty close to the windshield and the hole in my hood is the same as when i had my shaker on it...My question is i built a ram air pan to go on the carb and then seal off any air from the front of the car so it can only get it from the back of the cowl..We'll with it sealed off like that you can feel a difference in throttle response out of the hole and at highway speed...it doesnt feel as snappy when u stab the throttle the carb makes a weird sucking sound almost like its starving for air, but yet the one time i ran it at the track i had my best mph..at least thats what i am contributing it to.cause this sunday air was good and couldnt get it to run 102 plus .like it did in worse air!.. do u guys have the same problem? or is the carb not up high enough? I will takes pics tonight for you to see.... I welcome your responses

[grandville455]

Ok here's pics 1st pic nothing, second pic just the pan with filter, 3rd pic the pan with no filter,4th pic pan with filter and lid, 5th pic side view of it... ok so it feels the best without the pan on at all, responsive and pulls nice... next best is with pan and just the filter, good response but not as good as 1st, next is with filter and lid but pulls slow and doesnt have real good response, last is with out anything on pan it has a weird sound when accelerating and a very brief stumble when punched at 60 mph then it goes... all pulls were at 60 mph.. and from a 30 mph roll.. as have to be careful for police .... what do you think is going on?

[screamingchief]

Maybe try it with a base with less of a drop (flat) instead of that drop base you have on there now,my thoughts say it'll work better.

Sounds like with the lid on it it's restricting the inlet air and affecting the secondary opening action or such,and possibly the fuel bowl venting as well.

Sounds like anything in the air path is obstructing the flow really.

It also would help if the pan were a little bigger and not so close to the sides of the filter element,as that cuts down on the flow in that area as well likely.

A simple test might be to try a taller filter element if you have the room.

Just a few ideas.

[Formulabruce]

Mark Donehue's SCCA team really had some experiments with this in 67, 8, 9
The cowl induction builds pressure, but not at slow speeds ( just like your floor vent)
faster is more pressure as the wind makes a small down turn at base of windshield and the rest goes over the car.
This is why the Yenko style hood was developed. ( not sure if they ever made finctional ones though)
Chevy, and chevy powered ponchos in the 60's ( F bodys with 302 Z motors) also grabbed that air from the cowl itself above the heater box with an elbow assembly to the aircleaner to reduce hood drag, and used a flat hood.
The noise is normal, however at slow speeds, like taking off there may be a vacume created at that location.
Wish I had the early camaro wind tunnel pics on disc to show the cowl hood etc working. Very nice work on that air box!! ( nothing beats fresh air in a pontiac!)

[grandville455]

Bret It did feel better when i just added the filter and took it back out.... still not as good as without the pan on at all... Do you think the air that is coming in the back of the cowl is creating turbulence over the carb and the filter help straighten it out some? I could put another 3 inch filter on top and see what happens i guess? Funny thing is a few eeks ago when i treid this i lowere dmy shift point to 5200 and had the pan on with no filter.. it felt lazy on the 60fts but it ran its best mph 102.47 and i wasnt sure if it was cuase of the box or my shift points well this sunday we had some pretty good air and it would only go 101.80 same 5200 shift point but not using the pan, so i have to believe that it helps? just how to i tune for that lazy 60ft it was almost .05 quicker in the 60fts without that pan! but still mph better with it!. But I did change oil to before this last race and its always atleast .1 slower after a oil change so maybe it would have been 102 plus? too. I do have the hole in the hood so i have clearance for another 3" filter Bret.... Thanks Bruce I was just looking at pics that u were talking about today on the net ,lol... If i didnt have my damn heater box i would do exactly as jim hand... but i think i have to pull the inner fender dont i to get that out?

[rontiac]

What about trying one of these.

[grandville455]

hmmm u got one i can try instead of buying lol.......

[wh33lman]

This may not even be relevant, but...I was curious one day to see how effective the hood opening on my '81 Turbo TA was as cowl induction with the 400's open air breather just inches from the cleared out opening.

I tied plastic ribbons to the holes that used to mount the turbo lights and went for a drive. Air was not drawn in until I reached 35MPH. Faster you go after 35MPH, more the ribbons "stretched" towards air cleaner. By highway speeds you can be fairly sure all air is coming in through the "cowl".

So it took about 30mph to create enough low pressure area behind the cowl for the engine to begin to use that cooler air.

Once I put a slightly smaller diameter air-cleaner on my drop down pan. It fit, but pressed up against the inner ring which effectively blocked the lower 1" of the air cleaner and restricted the whole flow pattern of the drop down pan's design. Cost me 40hp till I realized what was up.

There are a lot of posts about those air-cleaner tops making cars slower, but most did not have an air-box. It has to be the easiest mod to track test.

[grandville455]

I am thinking that this set up when going down the road sees a big gulp of air when i open the carb up from the cowl and i am getting a lean condition..thats why when i put the lid on it feels better but alot slower cause its choking it out too much...I wonder if i just richen it up,, but i am already using .040 rods in the secondaries with a b hanger richest one of them all.. thoughts on that?

[Geoff]

The carb may need richening, drawing in the cooler air. Especially if the calibration was borderline lean. Cooler air is more dense & requires richer jetting. A lot will be dependent on how much difference in temperature there is when running outside cool air versus underhood. If you have done a good job of insulating the cold air box from ALL underhood heat, there could be a noticable difference in the inlet temperatures; richer jetting needed. If hot air is leaking in, there might be little difference in air temp & no jetting change needed. You also need to make sure that adding the filter & top does not create too small a gap between the air cleaner base & lid, more likely wih a drop base air cleaner assembly. The lid too close to the carb air vents, same deal, can also cause strange problems.

[grandville455]

Thanks Geoff... I changed my design last night,lol.... I took my old K&N velocity stack cut a 1" off the bottom and screwed it to the top of my moroso drop base... the top of the base now sits almost flush with the hole in my hood... so the air comes in from the cowl and doesnt havent to drop into the carb now it just follows to and down the stack... Its not completed yet,still have work to finish on it ,but i took it to work today with it on there and it performed very nicely!...I will take pics when completed for you all to see...

[wheelspin]

Darby,

Before you spend a lot of time tuning for your current scoop setup, consider sealing the hood and picking up pressurized cold air from the front of the car or from the firewall area/ air intake plenum @ the bottom of the w/shield. Incoming air over the hood is tumbling and turbulent, disturbing the airflow into the carb/s. I think that is one of the reasons why the Pro Mods have such a huge w/shield high scoop: in order to locate the inlet well above the hoodline and into a high pressure air zone.

Checkout good buddy and master fabricator Bart's (B-man), setup on his GTO bracket racer. He used a stock air cleaner housing w/ an extra snorkel that is hosed to fixtures located on the firewall. You could also pickup pressurized/cold air from the h/lite buckets and duct it to a similar airbox setup.

FYI: As reported here and in other reports, the air cleaner filter top has been proven to reduce power on most combos.

Les

[grandville455]

Thanks Les!.. I seen b mans car i liked how he did that ,but i cant .. i need the wipers in case it rains and my fenders are different than those of a 64 gto..The headlight buckets wont work not enough room battery etc... And no where to duct from way under either back up to carb so this is my best option for now... I think when i get the pan sealed to the hood it will be great it worked pretty damn good this morning..and it looks kinda cool .... Will take pics when done...

[grandville455]

We'll left work today and it had rained out so my scoop was full of droplets.. we'll i was talking to my gf on the phone as i was driving through town about 30mph maybe and u could see plain as day the droplets getting pulled off the scoop and being sucked into the scoop! it was cool as hell to watch... So I know now that i have good pull of air there.. Just have to richen up my secondary side i think for all the extra air i am pulling in when those beasts open up! I can only imagine the draw at 60+ mph.... Its done I will take pics later. Some may not like it but it works for me

[grandville455]

Ok update on my testing.... I tried my b hanger with my custom .034 rods/.. very bad stumble.. came back used a g hanger with same rods a tad better... went back to my original b hanger with my .041 rods CE... almost perfect out of the hole from 10 mph..If I had some .044's which i used to.. cant find them!.. I think it would be perfect... anyway car did not want anymore fuel.. it likes the same combination I had before.. B hanger with .041 rods ... But she does pull very nicely up top... we'll find out next sunday at the muscle car race ... heres some pics.... the last pic u can see that its basically flush with my hole in my hood so no drop into the carb now just hits the top of the stack and in it goes