[Tom Pugh]

I'm thinking about adding a ram air air cleaner assembly and opening the hood scoop on my 67 GTO. Question is; did ram air really add any measurable perfromance or was it basically a marketing ploy?

[Keith Seymore]

It's worth about .2 reduction in ET on our 65 tripower car.

From 12.40s to 12.20s. No nosepiece.

K

[steve25]

There no Ram air effect due to the hood openings being in a boundary area, however it allows cooler denser air into the carb.

[Formulajones]

Yep it works. Ive run my RA formula as well as the cowl induction on my Chevelle with and without and it's a measurable difference at the track. Like mentioned Keith sees 2 tenths. Mine were more like a tenth or slightly more.

[steve25]

If you can find one a fiber glass pan insulates much better then a steel pan if your after the biggest power gain for the buck.

[Skip Fix]

I had an old NMCA buddy who grafted a Holley drop base onto one to use a Holley on his 67 with an RPM intake.

[Tom Pugh]

Originally Posted by Keith Seymore

It's worth about .2 reduction in ET on our 65 tripower car.

From 12.40s to 12.20s. No nosepiece.

K

wow, thats like pulling a few hundred lbs. out

[steve25]

Well if your stock 67 air cleaner assy was one of the very highly restrictive louvered ones it’s easy to see how the RA set up would make a big power gain .

[gtospieg]

I didn't see a difference at the track with my 67. I feel like the brick like front of these cars makes the air just go right over the scoop. I think Chevy got it right with cowl induction. I do like the idea of pulling cooler air through the scoop.

[hgerhardt]

Originally Posted by Skip Fix

I had an old NMCA buddy who grafted a Holley drop base onto one to use a Holley on his 67 with an RPM intake.

I did the same thing back in the 90's. Then if you ever wanted to go back to a stock-height manifold, just use an airhorn spacer (1" IIRC).

[Formulajones]

Originally Posted by gtospieg

I didn't see a difference at the track with my 67. I feel like the brick like front of these cars makes the air just go right over the scoop. I think Chevy got it right with cowl induction. I do like the idea of pulling cooler air through the scoop.

Some things you might find interesting. Dad's 69 GTO with scoops facing forward in the center of the hood, which is much like a 67, is right in that area considered a dead zone of air flow.

When he switched over to a sniper stealth I already had the stock appearing fiberglass hood opened and modified to be functional with an L88 air box and drop base sealed to the scoops. Like you I figured it may not be worth much at the track with all the talk of a boundary layer of air, plus those factory scoops just don't stick up much, maybe an inch. But with the Sniper I could now see air intake temps. I was surprised to see the air temp differences with the Sniper. Monitoring IAT's showed that it is indeed pulling in outside air. Stopping for gas and heat soaking for a few minutes saw those temps rise to over 100 degrees, and would keep climbing the longer we sat, but as soon as we started moving down the road they dropped to almost spot on ambient temps. Stop at a red light and I could watch it climb 2-3 degrees, start moving and they come back down.

Whether or not it's an effective RA setup that makes more HP I don't really know, but it does make a difference in the air temps the engine is ingesting.
I will say this, the way I have his hood setup, it's the only way for the engine to ingest any air, through those 2 little scoops. Hasn't seemed to hurt performance. Making over 700 HP and it's gone 10's at 128 mph. Would it run better with a more efficient air intake? Possibly, but the coolness factor of having a one off functional hood setup is why I did it and that's not going to change.

Having a Sniper on my chevelle I can also see IAT's and it acts very similar to dad's car. I have the electronic door wired to stay open all the time. These hoods actually have 2 doors and draw the air in from the very back of the hood at the windshield through the electronic flapper, the vacuum operated door on top is just more of a gimmick.
With that said, I see the same IAT drop that nearly matched the outside ambient temps within a degree or two. It also climbs when the car comes to a stop. This is just part throttle cruising stuff. I do know this hood works at the track because if I take the cowl air cleaner off and run an open element under the hood the car does slow down a tenth give or take. It has always liked being sealed to that hood.

The neat thing about the sniper is that I can add or subtract fuel based on the IAT's the engine is seeing. On the really cold mornings when it's 30 degrees it will actually drive around with 30-32 degree IAT's as long as I'm moving, and I have the tune adding a pinch of fuel for the cooler denser air.

[Formulajones]

Another short story on my RA Formula that's interesting. Everyone knows those scoops are probably one of the best at grabbing outside air.

When I ran the iron intake on it and driving the car during the winter months, we're talking 20-30 degrees outside, driving 50-60 mph it would pull in that outside air and actually cool the intake down enough to make the divorce choke kick back on, no kidding. I'd slow down through town idling through 25 zones and the damn choke would be on. A couple minutes of idling like that and the choke would kick back off, but as soon as I'd get rolling 50-60 mph again, within a few minutes the divorce choke would cool enough to come back on. This was back when I had the heat cross over partially blocked to keep air intake temps at bay, and it worked maybe too good on the cold days. Since I've switched to the RAIV intake with it's separate cross over it's cured that issue. Now I can enjoy a cold intake and not activate that divorce choke on cold days. No need to block the cross over now.

At the track that car loves the RA setup and forces air into the air cleaner at what seems to be pretty aggressive at higher speeds. Any time I'd trap over 100 mph I'd get back to the pits and find the little crank case breather filter blown out of it's holder and laying in the very back of the air cleaner. I found that if I would go WOT to say 70-80 mph it would stay put, but any time I reached 100 mph or in that vicinity, I'd find that little filter sitting in the back of the intake, lol. I ended up wire tying that in place so it wouldn't move anymore. That car hates it when I disable the RA. Even removing the air filter element and keeping the RA functional is the worst I've seen that car run. My guess is without the filter element, the air is coming in at such force it's very turbulent in there and it just screws up the air flow into the carb. The filter element helps to slow down and straighten the air flow. The car slows down a half second without the air filter in place. Crazy!

[ZeGermanHam]

Originally Posted by Skip Fix

I had an old NMCA buddy who grafted a Holley drop base onto one to use a Holley on his 67 with an RPM intake.

I'm going to do the same in the next month or two. Seems like a cool mod.

[Cammer-6]

Funny story of my 68 Bird 400 and RA.
68 doesnt have any flappers.Its all or nothing.
I made some foam plugs to insert in the open scoops as we get a lot of rain here.
Before that I would just change the scoops to closed ones.
I put closed scoops on so I could wash car,was going around the block to dry it off.
First stop I revved it to get started and thought I saw top of hood move.
Sure enough when revved it would suck the hood down then pop up when I let off.
I idled back to the house and changed back to open scoops.

[gtospieg]

Formulajones...I agree the car definitely likes the open scoop. Not too sure it's effective at Ramming air in but it seems to like ingesting the cooler air. I think it may actually help the car run a bit cooler. When I built the car I needed a new hood and I decided if I have to buy a new hood and scoop I was definitely buying the open scoop. Doing the same on the current 67 I'm building now. As an aside...once I caught in a tremendous downpour and felt no ill effects from the scoop being open, and I drove it a couple of hours that way.

[Formulajones]

Yeah we've been caught in a couple of viscous downpours during the monsoon season here, blinding rain. Not on purpose but dads car did just fine, no ill affects from the scoops being open.

In fact we were heading to goodguys last weekend, about 100 mile trip down. Got caught in a rain storm that popped up, and as we climbed in elevation it turned to snow. Was coming down good enough to collect piles of snow under the wiper arms while driving. And he runs around in that car with drag radials on the back Seemed to do just fine though.