Hood scoop pressure too much on big end. SSAH Type

Posted By: GTSDave

Hood scoop pressure too much on big end. SSAH Type - 05/05/14 06:46 PM

Looks like I may have issues with my hood scoop working too well. Last outing on the big end my hood was wanting to lift up at the rear in the center. I was up in the 135mph range with a head wind.

Car is a 68 Barracuda FB with SSAH type HEMI scoop molded into a fiberglass hood. No carb / hood seal plate, just blowing down into the engine compartment.

What have you done to relieve pressure on the top end with your hood scoop? What do you suggest? What has worked for you in the past?

-Dave

Posted By: Cab_Burge

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 07:05 PM

Those cars(A bodys) are noterous for that regardless of the scoop type or size, it is the air pressure from the front end coming into the engine compartment trying to blow the hood off, not the air coming into the scoop

Put a carb. plate on it to seal the air from the bottom of the engine compartment and see if that helps, I would block the air from coming in from the grill, it will come in from behind the bumper and up from the K member area also

A good spoiler mounted in front of the radiator core support will help also

My tube chassis 1970 Cuda has issues also but I have not installed a spoiler or carb sealer yet

It trys to blow the hood off at 135+ MPH also on the throttle stop

it is worst at 145 MPH off the throttle stop

I need to block the grill off and install a spoiler also

Posted By: GTSDave

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 07:12 PM

I don't think the class rules (NSS) would allow me to add a spoiler. Was thinking of a belly pan instead of an engine diaper. Maybe I can kill two birds with one stone.

Pretty sure I cant block off the radiator area either.

-Dave

Posted By: Thumperdart

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 07:39 PM

Drill holes in the back of the scoop..............

Posted By: OUTLAWSSAA

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 08:24 PM

Dave, there's only one way to fix that problem. I had the same thing happen. You have to put in 8 pins. Three on each side of the hood, and that will take care of it.

Posted By: Chris2581

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 10:52 PM

Fastest I've gone was 116 and my hood does the same thing,although it now lifts against the hood pins.I have 3 pins across the back and 3 across the front.71 Demon with snorkel scoop.

Posted By: racerx

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 11:14 PM

Quote:

Drill holes in the back of the scoop..............

^^^This^^^ I'm thinking of trying with my 5"T/A hood.

Posted By: Thumperdart

Re: Hood scoop pressure too much on big end. SSAH Type - 05/05/14 11:27 PM

Quote:

Quote:

Drill holes in the back of the scoop..............

^^^This^^^ I'm thinking of trying with my 5"T/A hood.

Plus it really helped w/my O2 #`s WAY more solid probably due to helping w/the turbulence..........

Posted By: MR_P_BODY

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 12:07 AM

Block of the front... dont let the air in

Posted By: GTSDave

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 05:30 AM

Quote:

Dave, there's only one way to fix that problem. I had the same thing happen. You have to put in 8 pins. Three on each side of the hood, and that will take care of it.

Thanks Outlaw,

I am no where near as quick as you guys. I run a low deck wedge with a Jerico. Still launching fairly easy, but the thing is making great power so we are slowing it down until we get it tuned the way we want. We built it to run FX Classes. The MPH has me worried with the scoop the way it is because it is already trying to pull of the car on the big end and we don't have it turned up yet. It will only get worse.

Right now we have brackets glassed in and we are using the factory style hinges with no springs. Up front one dutz in the center with two pins in stock location.

I may end up drilling the holes in the back of it, and probably adding more pins. With the hinges pins wont work because of the angle it opens at, but it is worth looking into. I am not sure how it would work with airflow across the carbs if we drill the holes. I use a heavily modified STR intake with dual eddy 800's inline configuration.

Thumper do you have any pics of yours you willing to share? What are you running for cabs, and did the holes make that much difference in your O2 readings?

-Dave

Posted By: mikeysmopars

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 06:53 AM

Although i'm no authoraty. I made a base and sealed it except for the front edge about 3/4". mine has run 135 and i also have 6 pins, Three in front and back. I've never had a hood issue....Unless you count the time the pins we not in it.

Posted By: mikeysmopars

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 06:54 AM

Base

Posted By: mikeysmopars

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 06:55 AM

Hood

Posted By: dvw

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 12:35 PM

I've run nearly 148 with this one, 4 pins. It does move around some.
Doug

Attached picture 8135667-P1040562.JPG

Posted By: Keith Richards

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 02:52 PM

My '68 RR with a glass 6 pack hood raised up 1-1/2" every pass for years with no ill effects to the hood, some were I have a video of it, see if I can find it. My Challenger hood raises up about a inch as well it has a big pro stock type scoop and I drilled 4 - 1-1/4" holes in the back which had no effect so I just let it do it's thing as well as doesn't seem to hurt it either.

Posted By: Thumperdart

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 04:41 PM

Quote:

Quote:

Dave, there's only one way to fix that problem. I had the same thing happen. You have to put in 8 pins. Three on each side of the hood, and that will take care of it.

Thanks Outlaw,

I am no where near as quick as you guys. I run a low deck wedge with a Jerico. Still launching fairly easy, but the thing is making great power so we are slowing it down until we get it tuned the way we want. We built it to run FX Classes. The MPH has me worried with the scoop the way it is because it is already trying to pull of the car on the big end and we don't have it turned up yet. It will only get worse.

Right now we have brackets glassed in and we are using the factory style hinges with no springs. Up front one dutz in the center with two pins in stock location.

I may end up drilling the holes in the back of it, and probably adding more pins. With the hinges pins wont work because of the angle it opens at, but it is worth looking into. I am not sure how it would work with airflow across the carbs if we drill the holes. I use a heavily modified STR intake with dual eddy 800's inline configuration.

Thumper do you have any pics of yours you willing to share? What are you running for cabs, and did the holes make that much difference in your O2 readings?

-Dave

There`s an old post about "Thumperdarts scoop and ? photos" from several months ago but what I did was evenly space 5 tear drop holes across the back to release pressure and my scoop is trying to rip off the car above 135+ mph and the w/b is rock solid now w/other changes to the carb also.

Posted By: GTSDave

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 05:19 PM

Thumper,

Couldn't find that thread, but did find one where you had a couple of pics. Looks like they didn't need to be very big at all. Do you think they would work without the pan, or does it need the pan to work?

https://board.moparts.org/ubbthreads/show...amp;Search=true

mikeysmopars

Love your car. Thanks for the pics. It gives me some ideas for where to mount additional pins.

Thanks again to everyone who replied. It gives me some ideas to work with. Depending on the weather, we are planning to run in St. Louis this weekend, and if all goes well again over Memorial day for the Dave Dual Classic.

-Dave

Attached picture 8135862-img002.jpg

Posted By: Thumperdart

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 06:14 PM

Quote:

Thumper,

Couldn't find that thread, but did find one where you had a couple of pics. Looks like they didn't need to be very big at all. Do you think they would work without the pan, or does it need the pan to work?

https://board.moparts.org/ubbthreads/show...amp;Search=true

mikeysmopars

Love your car. Thanks for the pics. It gives me some ideas for where to mount additional pins.

Thanks again to everyone who replied. It gives me some ideas to work with. Depending on the weather, we are planning to run in St. Louis this weekend, and if all goes well again over Memorial day for the Dave Dual Classic.

-Dave

That`s it...............

Posted By: sshemi

Re: Hood scoop pressure too much on big end. SSAH Type - 05/06/14 09:54 PM

Sorry to highjack but what gains can be expected going from a stock Hood to a glass with hemi scoop on a -68 barracuda?
Anyone ever did a somewhat fair back to back test on this?

Posted By: a493demon

Re: Hood scoop pressure too much on big end. SSAH Type - 05/07/14 12:52 AM

I had to put a dzus at the back of mine .
it was lifting enough at the back that I could see the carb.

Posted By: MR_P_BODY

Re: Hood scoop pressure too much on big end. SSAH Type - 05/07/14 02:12 AM

Quote:

Sorry to highjack but what gains can be expected going from a stock Hood to a glass with hemi scoop on a -68 barracuda?
Anyone ever did a somewhat fair back to back test on this?

You should see .2 gain if sealed... maybe a bit more
depending on the current tune up

Posted By: BloFish

Re: Hood scoop pressure too much on big end. SSAH Type - 05/07/14 03:10 AM

Quote:

Drill holes in the back of the scoop..............

That's what I did

Posted By: THE GLASS MAN

Re: Hood scoop pressure too much on big end. SSAH Type - 05/07/14 03:40 AM

I make these hoods and scoops and have 2 of the 68 Hemi Cudas, one with the pan mated to the hood and the other completely open. I actually leave the pin off the center of the rear on both cars to let some of the pressure out of the engine compartment. Sure, it comes up about 2 inches on top end , but neither one has cracked or broke in 20 years. Fiberglass is very forgiving.

Posted By: sshemi

Re: Hood scoop pressure too much on big end. SSAH Type - 05/07/14 07:23 AM

Quote:

Quote:

Sorry to highjack but what gains can be expected going from a stock Hood to a glass with hemi scoop on a -68 barracuda?
Anyone ever did a somewhat fair back to back test on this?

You should see .2 gain if sealed... maybe a bit more
depending on the current tune up

Wow. I didnt think it would be that much.
Guess im gonna start saving some money.

Posted By: Monte_Smith

Re: Hood scoop pressure too much on big end. SSAH Type - 05/08/14 02:52 AM

Quote:

Quote:

Quote:

Sorry to highjack but what gains can be expected going from a stock Hood to a glass with hemi scoop on a -68 barracuda?
Anyone ever did a somewhat fair back to back test on this?

You should see .2 gain if sealed... maybe a bit more
depending on the current tune up

Wow. I didnt think it would be that much.
Guess im gonna start saving some money.

I wouldn't BANK on it netting you 2/10ths. As a matter of fact if the carb is not too close to the hood now with NO scoop, adding one may not help it at all. Most factory scoops were not put on because they worked. Most were for strictly looks or air cleaner clearance.

Monte

Posted By: justinp61

Re: Hood scoop pressure too much on big end. SSAH Type - 05/08/14 04:25 AM

My Dart has a 6 pack scoop on it, the top of the carb is about 6" from the top of the scoop. In the 1/8 it was off nearly .1 in a,b,a testing. It wasn't happy without the pan sealed to the hood.

Posted By: BloFish

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 02:47 AM

Here's what I did to mine.

Attached picture 8142679-image.jpg

Posted By: racerx

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 06:03 AM

^^^Did this help any^^^

Posted By: MR_P_BODY

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 06:10 AM

Quote:

Quote:

Quote:

Quote:

Sorry to highjack but what gains can be expected going from a stock Hood to a glass with hemi scoop on a -68 barracuda?
Anyone ever did a somewhat fair back to back test on this?

You should see .2 gain if sealed... maybe a bit more
depending on the current tune up

Wow. I didnt think it would be that much.
Guess im gonna start saving some money.

I wouldn't BANK on it netting you 2/10ths. As a matter of fact if the carb is not too close to the hood now with NO scoop, adding one may not help it at all. Most factory scoops were not put on because they worked. Most were for strictly looks or air cleaner clearance.

Monte

This is very true with those low style factory scoops..
most of them are JUNK but the mopar people HAVE to
have them.... they arent up in the clean air flow

Posted By: sshemi

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 09:36 AM

My carb is very close to the Hood now.
I even need to use a drop base with a 2,5" filter!
I wonder if cold air is just as important with E85 as with gas?

Posted By: BloFish

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 02:09 PM

Quote:

^^^Did this help any^^^

It did for me. It went from rising 2", to only 1/2".
And I do not have a pan to seal the carb.

Posted By: MR_P_BODY

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 02:24 PM

Quote:

My carb is very close to the Hood now.
I even need to use a drop base with a 2,5" filter!
I wonder if cold air is just as important with E85 as with gas?

Yes it is as important... air is air.. if its already
expanded you dont fit as much in

Posted By: cudaman1969

Re: Hood scoop pressure too much on big end. SSAH Type - 05/13/14 03:11 PM

Just thinking out loud but wouldn't the hood try to raise because of fast moving air (low pressure) above, than the slow moving air under the hood (high pressure)?

Like a convertible top