More aero stuff

[wickd]

I been reading some of these aero posts and thought I would show you guys how my front end is set up and see what you think. With this big block twin turbo setup I was looking for good cooling and I didnt feel like the sloped back radiator setup looked that good for max cooling. Even with the small block, the car never did cool all that great. I took duct tape one day and sealed the front up as tight as I could, filling in all the little cracks, holes around anything that was in the nose, ect. I got some high density foam and redid the foam over the rad support to get an air tight seal between it and the hood. Even with that it didnt seem like it made much of a difference to cooling capacity in the summer heat. Part of the problem was not having some sort of an air dam under the front of the car to catch more air to push through the radiator. I read a few articles on making radiators work better and decided to try my own idea. I got a new Dewitts aluminum radiator with the twin spal electric fans and stood it straight up, then built an aluminum duct in front of it to catch air for it. I think you guys might call my setup a bottom feeder. I put a big rubber air dam on the backside of the duct to catch lots of air. This setup left enough room in front of the duct to put intercoolers just behind the front grills, and still leave enough room for air from the intercoolers to go up and over the rad duct and into the engine compartment. I havent gotten around to the intercoolers yet so just the pipes are running through there right now. I also wanted some sort of vents in the hood to get rid of hot air so I bought a vented high rise hood, I had to add 1 inch to it to clear the carb hat. I built stainless boxes for the flat panel air cleaners then built ducting in the hood to seal them off from the engine compartment and they get fresh air from the windshield base area. On a side note, the other day I was driving it in a light rain and it was interesting how the rain drops moved on the windshield, on both sides the drops blew up the window but in the center section where the raised cowl hood part is, the rain drops moved down the windshield towards the bottom of it. I guess that tells me how the air flow is with the cowl hood, interesting. Anyway here are a couple of pics, I dont have a pic of my hood on this computer so the pic is of a car with the hood I used. Also a quickie drawing of how the radiator and ducting is set up. I was in town the other day and I blew a fuse on the electric fans so they quit. It was 85 degrees out and sitting at the stop lights the water temp would get up to around 210 but when I was moving at 35-40 mph, it would cool down to about 190. I actually drove around town for over an hour and the temps never did get above 210 degrees. I guess my setup is able to catch enough air even at those speeds to keep it cool, it surprised me. Anyway, what do you guys think?

Mike

Mike

 

[mrvette]

Mike, your ideas there and post above, bring up a new thought process with me on this very topic.....but my car is not even near as radical as yours....but located in FLORIDA, if you look at the sites below you see I did a up/over air induction also...but no where near the power and no turbos.....

I am curious how you got the hood clearance to straighten up the radiator....
my radiator is a stock core size for the '72 L48 a/c SBC....I am using a later Camaro Z28 radiator, aluminum with plastic tanks and dual spals with 100% shrouding and enough back space to pull through the entire core....

BUT, the rad is in the stock position on the replacement core support for some years now...fans angled down to the ground, same plane as the radiator...

so in your opinion would I gain a whole lot by straightening up the fans to flow back over the engine?? remount the spals?? AND, how did you get the clearance to straighten the radiator?? special rad??

as you can see from my pix, the hood opening is no longer an issue, reversed the hinges...hood pins in front....

:nuts::huh:

I did some ~100 mph airflow tests with my add on BBC hood bulge open in the back and underneath...yarn or pennies in tape indicate no air pressure differential on my car...but I have the operating wiper door, so the bulge is further forward...BUT no airflow in or out....so no lift, there, all in front of the radiator...

I issue is the a/c seems fine most of the time, but under extreme conditions, I wonder if redoing the airflow via Radiator would help a lot, or a time waster....

 

[JeffP1167]

I've pondered with the idea of using a entire 1990-up cooling capsule in my 82 vette. However not sure if it would bolt to the frame rails like a 90-up does.

 

[wickd]

The radiator is a Dewitts aluminum for a big block vette. I had to remove the front swaybar and notch the frame where the nutplates for the swaybar were to move the bottom back enough to get it to stand up. I am going to do some sort of a suspension swap down the road ayway so I am not too concerned about the front bar right now, just doing some experimenting. i was even thinking about tilting it forward, maybe on a 45 degree angle and see how that might work, that way the air coming in has a more straight through path. Mrvette, not sure what to tell you about yours, I can tell you its a lot of work standing the rad up like I did as I had to make a new rad support, anchor the front fenders back to it, and make the ducting. I also made new hinges, kinda copied the c-5 hinges so when the hood opens it raises so as to clear the radiator, duct, and the intake pipes coming up over the duct. I dont know the size of a c-4 radiator so I dont know how easy that would be to fit either.
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

 

[JeffP1167]

The radiator is a Dewitts aluminum for a big block vette. I had to remove the front swaybar and notch the frame where the nutplates for the swaybar were to move the bottom back enough to get it to stand up. I am going to do some sort of a suspension swap down the road ayway so I am not too concerned about the front bar right now, just doing some experimenting. i was even thinking about tilting it forward, maybe on a 45 degree angle and see how that might work, that way the air coming in has a more straight through path. Mrvette, not sure what to tell you about yours, I can tell you its a lot of work standing the rad up like I did as I had to make a new rad support, anchor the front fenders back to it, and make the ducting. I also made new hinges, kinda copied the c-5 hinges so when the hood opens it raises so as to clear the radiator, duct, and the intake pipes coming up over the duct. I dont know the size of a c-4 radiator so I dont know how easy that would be to fit either.
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

Not a vette but I have had two versions of trans am's ... one a 1982 with functional grills, the other a 1984 with the w-62 aero package with grill block of plates. Both had the same radiators and electric fans both 305's ... The 82 always ran cooler significantly. The 82's grill opening were not that large by any means but made a large difference in summer cooling and high speed cooling.

 

[BBShark]

The radiator is a Dewitts aluminum for a big block vette. I had to remove the front swaybar and notch the frame where the nutplates for the swaybar were to move the bottom back enough to get it to stand up. I am going to do some sort of a suspension swap down the road ayway so I am not too concerned about the front bar right now, just doing some experimenting. i was even thinking about tilting it forward, maybe on a 45 degree angle and see how that might work, that way the air coming in has a more straight through path. Mrvette, not sure what to tell you about yours, I can tell you its a lot of work standing the rad up like I did as I had to make a new rad support, anchor the front fenders back to it, and make the ducting. I also made new hinges, kinda copied the c-5 hinges so when the hood opens it raises so as to clear the radiator, duct, and the intake pipes coming up over the duct. I dont know the size of a c-4 radiator so I dont know how easy that would be to fit either.
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

Sounds like your setup is working well if you were able to maintain temps at low speed without the fans. For the fans to work at their best, you want a low pressure area behind the fans obviously. Your air dam should help with barging air into the radiator and, if wide enough, pushing air to the sides and out from under the car.

I don't know that there is a most efficient way to feed air to the radiator. Just make sure your fans are not trying to push air out of the engine compartment.

Very nice underhood packaging/fabrication work on your car. Great job, very impressive. Almost looks factory, if the factory were ever to produce a beast like that!

Do you have some details on the lift out hinges?

 

[69427]

........................
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

I don't know that it matters how you initially get the air to the radiator, as long as it's sufficient in volume/mass to pull out the number of BTUs to cool the engine. My understanding is that it's desirable to have a diffuser ahead of the radiator to convert the high speed/low pressure flow into low speed/high pressure air. This apparently is more efficient at promoting heat exchange than just having the air slam into the radiator surface.

 

[mrvette]

........................
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

I don't know that it matters how you initially get the air to the radiator, as long as it's sufficient in volume/mass to pull out the number of BTUs to cool the engine. My understanding is that it's desirable to have a diffuser ahead of the radiator to convert the high speed/low pressure flow into low speed/high pressure air. This apparently is more efficient at promoting heat exchange than just having the air slam into the radiator surface.

Diffuser?? you can't mean like a a/c cond, can you??

I sent a email to DeWitts about altering my Spals from directly parallel to the radiator, therefore blowing down toward the harm/balancer in same plane as the rad.....to a more upright position, leaving the rad alone....that makes the entire airflow pattern straight back over the engine...maybe forcing hot air outta the compartment side scoops, and aiding engine cooling, and increasing a/c effectiveness/less firewall heat loading....

anyone any comments??

they didn't seem to think it was worth the time/effort....

:crutches:

 

[phantomjock]

........................
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

I don't know that it matters how you initially get the air to the radiator, as long as it's sufficient in volume/mass to pull out the number of BTUs to cool the engine. My understanding is that it's desirable to have a diffuser ahead of the radiator to convert the high speed/low pressure flow into low speed/high pressure air. This apparently is more efficient at promoting heat exchange than just having the air slam into the radiator surface.

Diffuser?? you can't mean like a a/c cond, can you??

I sent a email to DeWitts about altering my Spals from directly parallel to the radiator, therefore blowing down toward the harm/balancer in same plane as the rad.....to a more upright position, leaving the rad alone....that makes the entire airflow pattern straight back over the engine...maybe forcing hot air outta the compartment side scoops, and aiding engine cooling, and increasing a/c effectiveness/less firewall heat loading....

anyone any comments??

they didn't seem to think it was worth the time/effort....

:crutches:

I'll let you know when -- I know?!
I see a couple of issues here -- Cooling - and air flow -- sorta linked...
Fans can pull or push through the radiator - DOOH.


But where should we send the air after that? And to what -- if any advantage/disadvantage?


Here's an interesting link to radiator "lean"and potential for ground effect:
http://www.jpslotus.org/main/ground.htm
Please note there was a definate advantage to the forward lean radiator....

There are more than a few pics about the forward lean radiator - and I think I'll try and incorporate a few: (these are from a Firebird site somewhere)


OPTION ONE - Corvette "Normal:"



ÖPTION TWO: LAYDOWN - DOWNWARD FLOW


OPTION THREE: UP EXHAUST:


OPTION THREE:
Gives a downward vector with the exhaust -- IF there is means to DIRECT the airflow (in addition to the fans to SUCK):


Now from the Lotus experience, and the firebird diagrams, the best seems to be OPTION THREE.

THEN: What is needed -- a place to send the airflow:


An interesting challenge - but not unlike the GT-40s etc with forward leaning radiators.

Getting the heat out of the radiator in stop and go traffic would be -- electric fan(s) and it might even keep the engine bay a bit cooler - but careful for "pre-heating" the carb intake air!
AN interesting aero phenom -- warm air (like through the radiator) carries more energy - and is less likely to separate! So more skin friction drag - yada-yada...

Just something to consider from -- off the wall!

Cheers - Jim

 

[mrvette]

Well, no one seems to think I am on to something, but I think so, and at some point soon enough, I am going to fab up another shroud/mount for the Spals, and aim them and the airflow through the shroud straight back at the front of the engine....just like a stock setup....

I think it's going to help a LOT with underhood temps...not engine cooling much, but to get that header heat outta the engine compartment....

and make the a/c better/more effective.......

:crutches:

 

[69427]

Diffuser?? you can't mean like a a/c cond, can you??

Gene, I mean a diffuser, just like the definition says in a dictionary.

 

[phantomjock]

Gene -
Maybe an extra cooling interface with a separate fan setup:


There are 2 Sides and so 2 Opportunities to consider!

It would help move air out of the engine bay too. Downside - the heat coming off the headers will lower the "delta-T" for the auxiliary radiator(s) and they wouldn't be as effective. But still better than none!


Cheers - Jim

 

[mrvette]

Thanks guys, but I don't see how I can get any extra fans under the hood, and aimed out the ducts I have....PIA to mod them to boot....

and the diffusers I dunno how to do them on this car.....

I still think to go with reangling the fans and still keep full shroud....

:3rd:

 

[JeffP1167]

Isn't a diffuser like a wing above the airdam like a 90-up vette has?

 

[big2bird]

........................
What is supposed to be the most efficient way to feed air to the rad? Underneath like a c-4 or through the front with a splitter pushing air in? Dont the corvette factory racers have a rad tilted forward and a duct opening coming out of the hoodjust behind it?

I don't know that it matters how you initially get the air to the radiator, as long as it's sufficient in volume/mass to pull out the number of BTUs to cool the engine. My understanding is that it's desirable to have a diffuser ahead of the radiator to convert the high speed/low pressure flow into low speed/high pressure air. This apparently is more efficient at promoting heat exchange than just having the air slam into the radiator surface.

Diffuser?? you can't mean like a a/c cond, can you??

I sent a email to DeWitts about altering my Spals from directly parallel to the radiator, therefore blowing down toward the harm/balancer in same plane as the rad.....to a more upright position, leaving the rad alone....that makes the entire airflow pattern straight back over the engine...maybe forcing hot air outta the compartment side scoops, and aiding engine cooling, and increasing a/c effectiveness/less firewall heat loading....

anyone any comments??

they didn't seem to think it was worth the time/effort....

:crutches:

I'll let you know when -- I know?!
I see a couple of issues here -- Cooling - and air flow -- sorta linked...
Fans can pull or push through the radiator - DOOH.


But where should we send the air after that? And to what -- if any advantage/disadvantage?


Here's an interesting link to radiator "lean"and potential for ground effect:
http://www.jpslotus.org/main/ground.htm
Please note there was a definate advantage to the forward lean radiator....

There are more than a few pics about the forward lean radiator - and I think I'll try and incorporate a few: (these are from a Firebird site somewhere)


OPTION ONE - Corvette "Normal:"



ÖPTION TWO: LAYDOWN - DOWNWARD FLOW


OPTION THREE: UP EXHAUST:


OPTION THREE:
Gives a downward vector with the exhaust -- IF there is means to DIRECT the airflow (in addition to the fans to SUCK):


Now from the Lotus experience, and the firebird diagrams, the best seems to be OPTION THREE.

THEN: What is needed -- a place to send the airflow:


An interesting challenge - but not unlike the GT-40s etc with forward leaning radiators.

Getting the heat out of the radiator in stop and go traffic would be -- electric fan(s) and it might even keep the engine bay a bit cooler - but careful for "pre-heating" the carb intake air!
AN interesting aero phenom -- warm air (like through the radiator) carries more energy - and is less likely to separate! So more skin friction drag - yada-yada...

Just something to consider from -- off the wall!

Cheers - Jim

I like that. Just like the Ford GT. It would also give more downdraft, with less air under the car.

 

[69427]

Isn't a diffuser like a wing above the airdam like a 90-up vette has?

A diffuser is an expanding volume ductwork to convert the high velocity/low pressure air from the grill/inlet area into low velocity/high pressure air prior to the radiator.

 

[mrvette]

Isn't a diffuser like a wing above the airdam like a 90-up vette has?

A diffuser is an expanding volume ductwork to convert the high velocity/low pressure air from the grill/inlet area into low velocity/high pressure air prior to the radiator.

That's what I don't quite understand.....if I concept it right, or not....
as applied to a shark....you are saying that adding fairing/duct work to smooth the airflow INTO the rad ??

I realize the grill/lights/body/bumper?/ all add restrictions to the airflow....but I left the backside of my headlights as open as I could to aid cooling....

 

[wickd]

In this old turbocharger book that I have, the author talks about cooling and he states that if you have a sealed duct directing air to the radiator that the opening of the duct only need to be about 1/3 the sq inches of the actual radiator to catch enough air to cool properly. True or false? I don't know. Mike is that what you are referring to as a diffuser? An opening thats smaller than the radiator to admit air but with increasing volume so as to let the air spread out as it moves to the radiator?

 

[wickd]

This is a question I've always wondered about, what was the reasoning of the shape of the l-88 hood scoop? Was it supposed to be cut out in the dip part of it for a vent or something? Maybe a dumb question so leave it to me to ask...

 

[Yellow73SB]

I was planning on eventually blocking off the lower valance and moving the spoiler forward. I would also then start to limit the air that comes through the front until it starts running hot, then I know how much air I need.