Front breather discussion.... Options

[Steve91T]

So now that I've decied to convert my LT1 front end to an LS1 front end, I've been thinking a lot about making it a front breather.

Why don't more people do it? Seems like a little trimming of the Impact foam and bumper beam and you could duct air directly to the radiator instead of scooping it from the bottom. The openings in the bumper are about 70 sq inches combined. Seems like it would be plenty for the radiator.

Seems like it would be a more efficient design and create less lift at speed.

For those who have done it, how does it preform?

[Blainefab]

Works great on a race car with an air dam that would not be streetable with the dam in place. The bottom breather has its own air dam with that deflector, and it works on the street because it is close to the front spindle centerlines.

[Steve91T]

So using the openings in the bumper that will allow for a straight shot the radiator won't work without an air dam? I would think that would be a more efficient way to get air to the radiator than scooping it from the bottom.

Not doubting you, just want to learn more about the aerodynamic differences between the two set ups.

[Blainefab]

So using the openings in the bumper that will allow for a straight shot the radiator won't work without an air dam? I would think that would be a more efficient way to get air to the radiator than scooping it from the bottom.

Not doubting you, just want to learn more about the aerodynamic differences between the two set ups.

Short answer is yes - just cutting a hole thru the front is not likely to work. Long answer is it depends - where and how you are using it, what the ambient conditions are, how well the opening is sealed, etc.

Consider what's happening with the OEM intake - look at the area the the air deflector is operating against, and how the intake duct shapes the flow up onto the front of the radiator. There is more effective area than what you have available in the grille area of the LS1 bumper cover. You can effectively increase the area by raising the local pressure with a dam, but it would take some experimenting to make it work without limiting your ground clearance.

[dailydriver]

Works great on a race car with an air dam that would not be streetable with the dam in place. The bottom breather has its own air dam with that deflector, and it works on the street because it is close to the front spindle centerlines.

Is the bolded above pertaining to the down force and stability at speed of the stock deflector/bottom breather set up, or ONLY about the airflow cooling ability (and WHY, if the latter)? (IMG:http://www.frrax.com/rrforum/style_emoticons/default/gr_confused.gif)

[Steve91T]

So using the openings in the bumper that will allow for a straight shot the radiator won't work without an air dam? I would think that would be a more efficient way to get air to the radiator than scooping it from the bottom.

Not doubting you, just want to learn more about the aerodynamic differences between the two set ups.

Short answer is yes - just cutting a hole thru the front is not likely to work. Long answer is it depends - where and how you are using it, what the ambient conditions are, how well the opening is sealed, etc.

Consider what's happening with the OEM intake - look at the area the the air deflector is operating against, and how the intake duct shapes the flow up onto the front of the radiator. There is more effective area than what you have available in the grille area of the LS1 bumper cover. You can effectively increase the area by raising the local pressure with a dam, but it would take some experimenting to make it work without limiting your ground clearance.

So, bottom breather not more efficient, but a large area makes up for lack of effiency, right?

If a front breather were ducted correctly, would that be a better way to get cooling air?

I'm planning on opening the bumper and foam to match the bumper cover openings and ducting it to the radiator and I'd like to add a splitter or air dam for track days but still keep it a front breather for the street.

[Blainefab]

Works great on a race car with an air dam that would not be streetable with the dam in place. The bottom breather has its own air dam with that deflector, and it works on the street because it is close to the front spindle centerlines.

Is the bolded above pertaining to the down force and stability at speed of the stock deflector/bottom breather set up, or ONLY about the airflow cooling ability (and WHY, if the latter)? (IMG:http://www.frrax.com/rrforum/style_emoticons/default/gr_confused.gif)

I was addressing ground clearance needed for street use vs race use - the closer the air dam/deflector is to the spindle centerline, the lower the dam can be without scraping, for a given grade change.

[Steve91T]

Other than race cars, nobody has made their car a front breather?

Alan, two more questions.

1: Is 70 sq inches a large enough opening for adequate cooling?
2: Any issues that you know of with cutting two 5x7 openings in the bumper beam?

[dailydriver]

Works great on a race car with an air dam that would not be streetable with the dam in place. The bottom breather has its own air dam with that deflector, and it works on the street because it is close to the front spindle centerlines.

Is the bolded above pertaining to the down force and stability at speed of the stock deflector/bottom breather set up, or ONLY about the airflow cooling ability (and WHY, if the latter)? (IMG:http://www.frrax.com/rrforum/style_emoticons/default/gr_confused.gif)

I was addressing ground clearance needed for street use vs race use - the closer the air dam/deflector is to the spindle centerline, the lower the dam can be without scraping, for a given grade change.

OK, thanks! (I did not even consider the ground clearance issue. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/twak.gif) )

[Blainefab]

Other than race cars, nobody has made their car a front breather?

Alan, two more questions.

1: Is 70 sq inches a large enough opening for adequate cooling?
2: Any issues that you know of with cutting two 5x7 openings in the bumper beam?

My SWAG is 70" is not enough - measure the area of the entry into the OEM bottom breather plenum - that is somewhere about 5" - 7" x the full width of the radiator - I would consider that a minimum since you will likely have a lower pressure in your duct than exists in the OEM duct.

Here's my first iteration front breather on my LT1 car - there is a sealed duct from the opening to the radiator, and I removed the airdam to drive the car to events - which were 400 to 1200 miles one way. I had no overheating issues cruising on the freeway, but with my gearing my cruise RPM was in the 1500-1800rpm range, with no AC. There is a lip on the top of the opening to help pack air into the duct - in the pic it is on edge so not obvious.

(IMG:http://blainefab.com/projects/aeromaro/photowize2004%20209.jpg)

At 185mph, there is a LOT of cooling available with the front breather and air dam, and the the opening creates drag, so in later events I taped off parts of the opening, and removed the upper lip, for the races - like this:

(IMG:http://blainefab.com/projects/aeromaro/photowize2004%20202.jpg)

which worked well, till I got too greedy and taped off too much - probably 30% less than that last pic, for my last ORR race on NV318 - got my fasted top speed but coolant temp went to 250+ and the clutch started slipping so we only averaged a tick over 170.

The bumper beam does tie the fronts of the frame rails together - cut the beam up and you'll lose some rigidity up there, and a minor front corner impact will be more likely to pop the radiator and require frame pulling to repair.

[Steve91T]

Measuring the opening of my LT1 front end, I figure you had a little less than 140 sq inches of opening with your ORR Camaro....about double what I would have. I think the LS1 bumper cover would do well with the center removed as a front breather with about 240 sq inches of area. A tubular bumper would probably be a must though and the looks would suffer.

I don't want to mess with that right now, maybe someday. Thanks Alan for taking the time to help clear that up. It's something I've always wondered about.

[athornt2]

Measuring the opening of my LT1 front end, I figure you had a little less than 140 sq inches of opening with your ORR Camaro....about double what I would have. I think the LS1 bumper cover would do well with the center removed as a front breather with about 240 sq inches of area. A tubular bumper would probably be a must though and the looks would suffer.

I don't want to mess with that right now, maybe someday. Thanks Alan for taking the time to help clear that up. It's something I've always wondered about.

Before I put aero on my AI Camaro, I ran a front breather with no cooling issues at all. My car was a street/track car for a short while.

[Steve91T]

Measuring the opening of my LT1 front end, I figure you had a little less than 140 sq inches of opening with your ORR Camaro....about double what I would have. I think the LS1 bumper cover would do well with the center removed as a front breather with about 240 sq inches of area. A tubular bumper would probably be a must though and the looks would suffer.

I don't want to mess with that right now, maybe someday. Thanks Alan for taking the time to help clear that up. It's something I've always wondered about.

Before I put aero on my AI Camaro, I ran a front breather with no cooling issues at all. My car was a street/track car for a short while.

Can you give me more information about your set up?

[Bud M]

At 185mph, there is a LOT of cooling available with the front breather and air dam, and the the opening creates drag, so in later events I taped off parts of the opening, and removed the upper lip, for the races - like this:

(IMG:http://blainefab.com/projects/aeromaro/photowize2004%20202.jpg)

which worked well, till I got too greedy and taped off too much - probably 30% less than that last pic, for my last ORR race on NV318 - got my fasted top speed but coolant temp went to 250+ and the clutch started slipping so we only averaged a tick over 170.

The bumper beam does tie the fronts of the frame rails together - cut the beam up and you'll lose some rigidity up there, and a minor front corner impact will be more likely to pop the radiator and require frame pulling to repair.

Looks like you're having some website issues, Alan.

[athornt2]

Measuring the opening of my LT1 front end, I figure you had a little less than 140 sq inches of opening with your ORR Camaro....about double what I would have. I think the LS1 bumper cover would do well with the center removed as a front breather with about 240 sq inches of area. A tubular bumper would probably be a must though and the looks would suffer.

I don't want to mess with that right now, maybe someday. Thanks Alan for taking the time to help clear that up. It's something I've always wondered about.

Before I put aero on my AI Camaro, I ran a front breather with no cooling issues at all. My car was a street/track car for a short while.

Can you give me more information about your set up?

It was a 98 ls1 with an ASA cam. I had a C&R double pass radiator with an aluminum shroud that ran to the inlet in the nose.

(IMG:http://i811.photobucket.com/albums/zz31/athornt2/shroud_zpsncyttbey.jpg)

I tracked the car twice in this configuration before building the shroud to vent the air out of the hood. No cooling issues, just massive buffeting of the hood.

(IMG:http://i811.photobucket.com/albums/zz31/athornt2/shroud%202_zpsqyequfcl.jpg)

[athornt2]

Measuring the opening of my LT1 front end, I figure you had a little less than 140 sq inches of opening with your ORR Camaro....about double what I would have. I think the LS1 bumper cover would do well with the center removed as a front breather with about 240 sq inches of area. A tubular bumper would probably be a must though and the looks would suffer.

I don't want to mess with that right now, maybe someday. Thanks Alan for taking the time to help clear that up. It's something I've always wondered about.

Before I put aero on my AI Camaro, I ran a front breather with no cooling issues at all. My car was a street/track car for a short while.

Can you give me more information about your set up?

Then built the outlet shroud and vented the air out of the hood. I ran in this configuration for a few weekends before adding aero. No cooling issues, but could feel the added frontal downforce. The car became loose at speed.

(IMG:http://i811.photobucket.com/albums/zz31/athornt2/Shroud%203_zpsuqwisg6q.jpg)

(IMG:http://i811.photobucket.com/albums/zz31/athornt2/Shroud%204_zpsoqjrqik6.jpg)

This post has been edited by athornt2: Apr 25 2015, 03:43 PM