Air filter on webers

[Caprimaniac]

Great, Jac.

Thanks alot. Did you write & sketch that note?

It's interesting. As you can see from the photos, the angeled rear face of the hood scoop have been removed. And me & my pals have been trying to figure wether this is a low or high pressure are. - Suitable for wenting or intake. We, maybe, solved this question with 3 inch of wool thread. While driving, the thread clearly made is way out of the opening. Which, made us conlude it is a low pressure area. - The oposite to the connclusion in your note. Even more, our thery was that the high pressure zone was above the ventilating plenum- exactly as the note says.


Impressive you could see it was a early Capri from the engine bay pics. Although, if you've stared into a Capri enginebay earlier in life- it's been etched onto your retina.... And what's funny is that I've asked for info on airstream/ windtunnel/ high-low pressure zones on Capri fora without anyone coming up with anything.

Once again; CC has alot of great resources - even Capri related! I have come across other people with Capri knowledge at CC before. I have also stated (somewhere) that I have no Cobra, but a Capri and use (& maybe contribute?) the weber & small block ++ resources.

[zrayr]

Originally Posted by Caprimaniac

"...............As you can see from the photos, the angeled rear face of the hood scoop have been removed. And me & my pals have been trying to figure wether this is a low or high pressure are. - Suitable for wenting or intake. We, maybe, solved this question with 3 inch of wool thread. While driving, the thread clearly made is way out of the opening. Which, made us conlude it is a low pressure area. - The oposite to the connclusion in your note................."

your testing with the wool thread, while admirable, has led you to the wrong conclusions. The rear end of hood scoops, just forward of the windshield has long been known to be a high pressure area.

Ford wind tunnel testing done at the request of Carroll Shelby in the 1960's (for the GT-350 development) showed that a hood scoop with the opening in the rear was much more effective in directing air to the carb & engine bay versus an opening in the front of the scoop. Shelby concluded that, despite this advantage of the rear opening scoop, Shelby Mustangs would have front opening scoops solely for cosmetic purposes. They just looked better. Function took a back seat.

Z.

[bobcowan]

Originally Posted by zrayr

your testing with the wool thread, while admirable, has led you to the wrong conclusions. The rear end of hood scoops, just forward of the windshield has long been known to be a high pressure area.

Z.

Yes, and no. The high pressure area has always been at the base of the windshield. And that means the small area right at the base. It's not a very big zone. On an older Mustang, that would be at the cowl vent area. As you move further away from the base, you lose that small high pressure zone.

The yarn test is pretty accurate and doesn't lie; where the yarn goes is where the air flows. It show that the back of the hood scoop on the Capri is probably feeding that high pressure zone.

Look at the cowl unduction hoods on a Camaro that's designed to work, and not just look good. The opening is moved back as far as possible to get it into that zone, and still allow the hood to open. If you wanted to take advantage of that high pressure zone on a Cobra, you'de have to get your air from the same place. Extend the air cleaner back, and create a new opening at the cowl; or extend the rear opening hood scoop back to within a few inches of the windshield.

Look at the air cleaner set ups for a cup car. It actually gets all it's air from the cowl area, directly at the base of the windshield.

[Bill E]

I had a lot of help from an aerodynamics company on this car. Lots of testing was done on this set up. This is the set up you want for the best results . It is a lot of work. You will need a tilt front end to pull it off. This could gain as much as 20 MPR in the top end. This car has tied the track record at Thunder hill at one time.

[Jac Mac]

Originally Posted by Caprimaniac

Great, Jac.

Thanks alot. Did you write & sketch that note?

It's interesting. As you can see from the photos, the angeled rear face of the hood scoop have been removed. And me & my pals have been trying to figure wether this is a low or high pressure are. - Suitable for wenting or intake. We, maybe, solved this question with 3 inch of wool thread. While driving, the thread clearly made is way out of the opening. Which, made us conlude it is a low pressure area. - The oposite to the connclusion in your note. Even more, our thery was that the high pressure zone was above the ventilating plenum- exactly as the note says.


Impressive you could see it was a early Capri from the engine bay pics. Although, if you've stared into a Capri enginebay earlier in life- it's been etched onto your retina.... And what's funny is that I've asked for info on airstream/ windtunnel/ high-low pressure zones on Capri fora without anyone coming up with anything.

Once again; CC has alot of great resources - even Capri related! I have come across other people with Capri knowledge at CC before. I have also stated (somewhere) that I have no Cobra, but a Capri and use (& maybe contribute?) the weber & small block ++ resources.

Yep, the note was sketched up on the 'paint' program of the PC, Have been involved with several ''OSCA'' Capris here in NZ,[ Open Saloon Car Association]', Built another 351c powered one only 5 years ago for a local guy who wanted to relive his youth. They were a very popular car in the class in the early 70's/80's.
We used the 'tuft' test on the TVR I work on to establish the 'zone', also if you have a close look at some of the original 'Daytona Coupe' pics you will see the intake opening is about 10" wide by 3" high on a reverse slope area right at the back of the hood and about 8" to 10" in front of the w/screen base, works fine for them as well. Nothing much will happen with the tuft until you get up around 40/50 mph, but from there onward its all good, the better you seal the airbox to the hood or plenum area the better it gets..

With regard to the mistaken indication that it was better as an outward vent, this comes from too much air being rammed in around the radiator etc, to cure this use a front airdam to create a low pressure area under the car and add vent holes to the inner guards behind the front axle line, the front wheels create another low pressure area behind them to assist in evacuation under the hood. Once you get the intake air from outside and realise that most radiators only require an intake/grill area approx one third of the radiators core area you will start to get on top of the issues your having.... its not really a matter of getting more air in, its more a case of getting the heated air out.

[Caprimaniac]

This is an interesting discussion.
A rear facing scoop with opening as close to the windscreen is good; here is a high pressure zone - 100% true. As you all say. After looking at all kinds of pressure zone/ IR- photos of wind tunnel cars I could come across- the highest pressure zone is to be found at the front of the car- at least on a road car with some frontal area. (On a sleek can- am racer the picture is different.) That is why I scooped the air fron the grille, which ofcours also serves the rad and the oil cooler. And also- of course- hot & unwanted under-bonnet air is going out on the middle flanges of the hood- a low pressure area.

As a friend did the wool- thread/ yarn- test, I do not trust him and will do it all over again to see what conlcusions i can find.

Yes, Jac Mac- you are probably correct on the "too much air under the bonnet" theory. In the pictured Capri there's much more restricted front air intake area than on my friends ride. Hopefully, it will do wonders... Also a different outcome of the Wooly experiment.

Very interesting to see you have been working on the NZ Capri racers. Been looking at some V8 Capri's from the green island, although some time ago. I have read alot of your posts in the Weber- department. I was 100% certain you inhibited US of A as Capri's are quite popular as a racer there, as well. (Although- used to be is a better statement- there were more in the 80's, as I understand, than now.)

It's a small world and you come by people with Euro- Capri experience wherever you go. Her, there, Corner Carvers, SBFtech and Club Cobra.

[bobcowan]

Originally Posted by Caprimaniac

It's a small world and you come by people with Euro- Capri experience wherever you go. Her, there, Corner Carvers, SBFtech and Club Cobra.

Back in the late 80's I was stationed in Sicily, Italy, for a couple of years. I drove a '70 Capri with a V6 and four speed. What great little car that was. Fun, sturdy, reliable, and fast. Everybody called it "The Silver Bullet". We took some great road trips in that car.

I really wanted to bring it back to the US, but it was too expensive to make the conversion. I'v never seen another one like it.

[Caprimaniac]

Bob; some of the US military personell in Europe did. Or some got themselves a US- spec Capri when they got home....(The Europen built Capri was so popular in the US that they had to stop importing it in 76 as they needed sales for the Mustang II to move up.... It shared the 2.8V6 with the Capri, but the Capri was lighter & quicker. After a Couple of years the new "US" Capri- model arrived, based on the Mustang)I have been chatting alot over the years wit Capri- owners in the US, and even made some friends!


Anyway: Now comes what I started off to do an hour or so ago....

Jac-Mac: You & your scetch are 100% correct and my friend is noe longer to trust (because he has to much air under the bonnet). After 1 day of driving, on road and track, I did not even get a tiny glimpse of the piece of rag hanging down from a piece of duct-tape in the centre of the hole where the rear end of the scoop used to be.

It is a high pressure zone. (And I will fill it in with fibreglass, as it used to be.)

[FUNFER2]

I'm using the single K & N type of filters on my 8 stack. Some of the screen type can be too fine and rob HP and others are too open and can suck in debris.

On "Motortrend TV" channel on youtube had a 613 HP Hemi and on the dyno the screen brought it down to something like 460 HP. If I can find the vid I'll post it.

With the K & N oval type I had, I put a fair amount of the spray oil , and it choked the TQ & HP by 20 & 25. Lesson, spray them lightly !

[razerwire]

itg air filters. Have on csx car, air horns have to be trimmed a little, twm 58 mm fuel injection. Was lots of pictures with foam on and off but cant find now, would like to find old pictures where car was on Kroyer dyno because you can click on them and goes to full size.

[FUNFER2]

Originally Posted by FUNFER2

I'm using the single K & N type of filters on my 8 stack. Some of the screen type can be too fine and rob HP and others are too open and can suck in debris.

On "Motortrend TV" channel on youtube had a 613 HP Hemi and on the dyno the screen brought it down to something like 460 HP. If I can find the vid I'll post it.

With the K & N oval type I had, I put a fair amount of the spray oil , and it choked the TQ & HP by 20 & 25. Lesson, spray them lightly !

Ok, found the video. It's about 14:00 minutes in.

https://m.youtube.com/watch?v=vFboNbYx0BI

When I get my new engine and trans in the car, I'll test my fabric type on the engine and off, on my friends chassis dyno then post the results. With winter coming I don't know when that will be.

[Gaz64]

I prefer to run one large rectangular airfilter like from R2C meant for a sprintcar.

Another option for hood clearance is a rectangular from K&N of about 2 inch height.

Can 8 individual filter elements flow the required demand per cylinder at the on/off rate compared to the demand through a grouped airfilter element?