Road Race Ducting Brainstorm

[AngelOfPassion]

Hopefully within the next few months I am going to start ducting my FMIC and Radiator. I have been reading through a few threads on here and have seen a lot of good examples of how to duct upward to the hood with a sealed vent. However I wanted to get some input of an idea I had with mine. This is my first road race car so I am inexperienced and wanted to get some input before I start molding.

I was thinking of making a duct that attaches to the radiator like normal. However, instead of having the duct carry the air upward to a sealed hood vent, I was going to have it carry downward and exit underneath the car.

I have a few concerns though:

I am worried about the pressure under the car. I am worried that the area under the car would try to suck air in instead of help it escape. Which would make cooling worse even with the help of fans pushing the air out.

I am worried this will generate more lift. Would directing the air downward from the radiator create any lift? If so, could I add a turn to the ducting to make the air travel backwards instead of downwards?

I am worried that my under hood temps would rise, but my coolant temps would fall. Even if this would work to create better airflow for the radiator; would the lack of air being blown onto the turbo/manifold from the radiator fans being sealed inside a ducting chamber cause under hood temps to rise? If so, are there any negative side effects to this happening?

Those are my main concerns. I have just never seen this done so I am assuming there is a reason behind that. However, I am not an expert, I am hoping that this could become an effective cooling idea.

Here is a picture to describe the type of duct I would be creating, but molded to exit underneath the car:
EDIT: This is not my work It is a picture of another members car as an example. Sorry for not clarifying.

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[greengoblin]

Point blank. There are damn good reasons every race car has it duct upward out the hood. You have also touched on several reason why it should.

Kevin

 

[952g63t]

Sounds like venting up would be your best solution. It would be a compelling argument to modify your hood by adding vents to avoid the temperature variations altogether, or trying to source an aftermarket. My biggest concern with a vented hood would be water leaking into the bay, but with your solution you can mitigate most of that by sealing the ducting-box similarly to an in-bay CAI. I would even go as far to say that you have product concept that has enough usefulness to manufacture and sell in the aftermarket parts arena.

 

[jtmcinder]

The only other issue is cooling the turbo. I'm not sure about completely blocking the flow of air across it, as your mock-up would do. If there is any way to include the turbo in your air-path, that would be great.

On cars with back-mounted turbos (i.e., the engine is the other way around, with the exhaust towards the back), such as an Evo X, you can set up two air paths. One comes through the IC and radiator and goes up and out through the hood. The other comes in through the hood and goes down across the turbo and out the bottom. That seems to work great, but might be really (only) a rally-car thing, where the air under the car is less of a concern. Plus, there's no way to get it to work on a front-mounted turbo, so it's not something to copy; just something to think about to free up your mind. For a DSM, I'd be looking for a way to have the air also move over the turbo before going out through the hood.

 

[greengoblin]

Wouldn't the water and oil cooling of the turbo offer enough cooling for it? Also short of a full under pan there should still be airflow in the bay area.

 

['97boostinGST]

Isn't that Beau's setup for his race car?

 

[greengoblin]

Sounds like venting up would be your best solution. It would be a compelling argument to modify your hood by adding vents to avoid the temperature variations altogether, or trying to source an aftermarket. My biggest concern with a vented hood would be water leaking into the bay, but with your solution you can mitigate most of that by sealing the ducting-box similarly to an in-bay CAI. I would even go as far to say that you have product concept that has enough usefulness to manufacture and sell in the aftermarket parts arena.

The hood ducting in his pic is of another members car.
More of it can be found here :

http://www.dsmtuners.com/forums/dsm-build-journals/431164-bbrtuning-time-attack-nasa-tt-99-gsx.html

 

[AngelOfPassion]

I am curious about the cooling of the turbo. Do you guys think that cutting off the turbo from the path of the radiator fans would have negative effects?

I guess I can see the temperature in that area increasing which would make the air coming in through the intake possibly hotter... I wonder if I can somehow include the turbo in the sealed vent. That would take a lot of fabrication to mold it around everything back there... and it may not even work .

Any other inputs on the turbo heat?
Any other things I should be looking out for?

 

[Evo3Codriver]

But why? Do you have overheating problems you haven't been able to solve otherwise? I hate adding stuff in the engine compartment that is just going to be in the way when I need to service or inspect something. Unless you mount the ducting to the hood so it lifts out of the way when you open the hood.

I drive my 1G w/ full race motor at nearly race speed hundreds of miles into depths of Canada to rallyraces and the entire underneath of the engine compartment is sealed w/ metal skidplate so no air escapes out bottom. Sometimes I'll have a radiator half packed w/ mud. W/ oil cooler, aluminum radiator and hood venting, never runs hot.

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The kidney vents in rear of hood seem to release more heat than the radiator/turbo vent.

 

[L1v1ng L3g3nd]

Instead of putting some wierd looking vents in the hood, I would just take longer bolts and metal sleeves to bring the hood up a litte on the mounts (don't know how this is called in the english language).

Like this german guy on his time attack evo:

 

[AngelOfPassion]

@ EVO3

Well temps here are above 120F here in the summer and racing conditions are harsh on the track. A good ducting system really helps. And this car is not my daily. I am building it specifically for maybe 1-2 road racing events every few months. I am keeping it street legal though just in case I need it.

@Living Legend

That doesn't work at all. The area behind the hood is a positive pressure zone in the aerodynamics of our cars. It would suck air in, not let it out. Which would create lift and drag and make the cooling system actually work less.

 

[jtmcinder]

Why do we have to deal with the "lift the back edge of the hood" suggestion in every one of these threads?

No, don't answer that. It was rhetorical.

Anyhoo, I don't know for sure whether cutting off the airflow across the outside of the turbo and exhaust manifold will cause serious problems, but I strongly suspect that it will. Most of all, that little oven you'll create between your ducting and the engine will almost definitely heat up the head, which would be bad. But I'm not suggesting a complete re-think. I'm suggesting that the ducting tuck under and around the back of the turbo, so that air is force across the turbo and up around the exhaust manifold being exiting through the hood. The trick here would be to have the duct almost seal the front edge of the valve-cover to the hood, so all of the hot air exits upwards. That's really the difference between this and what everyone with hood-vents has already done. Put some serious effort into getting all of the hot air out of the engine bay, along with trying to use the partial vacuum of the hood-vent to pull in more air from the front. All I'm suggesting is that the turbo and exhaust manifold being inside this air-path, not behind it.

 

[Evo3Codriver]

@Living Legend - And look, that Evo's hood is vented up front. Putting spacers in the hinges does help and hoods designed to allow air to escape there is called cowl hood. Regarding the pressure theories, if you cram enough air into your engine compartment like I have w/ my hacked to hell front bumper, there'll be enough pressure inside engine compartment to overcome pressure at windshield. Also, sitting on the grid there is no windshield area pressure to overcome and hot air rises.

Yeah, its still 100 degrees where/when I play w/ my car, sometimes even high 90s in eastern Canada at sealevel. Real difference is we have shade trees. But if you aren't overheating, all you need is fresh cool as possible air to your air intake. You can also shield your intake from rest of hot engine compartment.

 

[kamikazeredneck]

There is a lot of info on this site that states what both jtmcinder and what Beau has done as being right.

If you look at the linked page already posted about Beau's car you will see that what he is doing works very well for him and it has worked very well for others as a cheep and simple solution.

Now on the other end of that debate there is gixxerdrew's solution which was to leave it open and pull the air out while driving at speed. (I'm sure most people in this debate has already seen his page and/or build) This solution works very well for him but also took a lot of engineering to make work effectively. This would probably be out of reach for the average weekend driver but worked great for gixxedrdrew.

Now to the questions with the turbo cooling. If we are talking about the cooling of the bearings (which I believe we are) then the best thing to do is to cool them with air as much a possible. Now there is many types of cooling for the turbo bearings but with the most common water/oil cooling you will not need as much air to cool the turbo as say the oil only option which uses oil and air to cool the bearings. With the oil and air cooling then yes you should use air to cool the turbo all the time so putting a shield up in front of the turbo would not help with the air getting to the turbo. With oil/water cooling you will be utilizing the radiator and cooling system of the car to get the air cooling required to cool the turbo.

Now to the cooling of the cylinder head and other components. With all the components of the engine connected through the engines coolant system, the ail cooling required to cool the engine will be coming from the radiator and flowed through the coolant system to the components the need that cooling.

I hope this makes sense to people and will help people understand the different methods to ducting. I did not write this to step on anyone's toes or disprove anyone but to help people understand the system and so they can make decisions based on facts.

 

[AngelOfPassion]

Why do we have to deal with the "lift the back edge of the hood" suggestion in every one of these threads?

No, don't answer that. It was rhetorical.

Anyhoo, I don't know for sure whether cutting off the airflow across the outside of the turbo and exhaust manifold will cause serious problems, but I strongly suspect that it will. Most of all, that little oven you'll create between your ducting and the engine will almost definitely heat up the head, which would be bad. But I'm not suggesting a complete re-think. I'm suggesting that the ducting tuck under and around the back of the turbo, so that air is force across the turbo and up around the exhaust manifold being exiting through the hood. The trick here would be to have the duct almost seal the front edge of the valve-cover to the hood, so all of the hot air exits upwards. That's really the difference between this and what everyone with hood-vents has already done. Put some serious effort into getting all of the hot air out of the engine bay, along with trying to use the partial vacuum of the hood-vent to pull in more air from the front. All I'm suggesting is that the turbo and exhaust manifold being inside this air-path, not behind it.

I actually REALLY like this idea. To kindve separate the engine, manifold and turbo off from the rest of the bay. Have the rad fans blow air on all of it. Then, the air escapes through the hood. I could totally fab up something to acomplish this.

Edit: Front of engine* Not entire engine haha

Now to the questions with the turbo cooling. If we are talking about the cooling of the bearings (which I believe we are) then the best thing to do is to cool them with air as much a possible. Now there is many types of cooling for the turbo bearings but with the most common water/oil cooling you will not need as much air to cool the turbo as say the oil only option which uses oil and air to cool the bearings. With the oil and air cooling then yes you should use air to cool the turbo all the time so putting a shield up in front of the turbo would not help with the air getting to the turbo. With oil/water cooling you will be utilizing the radiator and cooling system of the car to get the air cooling required to cool the turbo.

Now to the cooling of the cylinder head and other components. With all the components of the engine connected through the engines coolant system, the ail cooling required to cool the engine will be coming from the radiator and flowed through the coolant system to the components the need that cooling.

My turbo is water and oil cooled. So I think it will be ok. I am worried about creating an oven syndrome under my hood because the vent would be sealed off from the rest of the bay, not allowing any air to escape besides under the car.

But if I take jtmcinder's idea. I think it will work way better and really solve heat problems.



@ EVO3 and Living Legend

It works on an Evo, NOT A DSM, end of story.

 

[greengoblin]

I would also do yourself a favor and send Beau a pm and see what he has to say about his under hood temps. No need to guess if somone has a working unit. I'm sure he would be willing o talk about it.

 

[kamikazeredneck]

My turbo is water and oil cooled. So I think it will be ok. I am worried about creating an oven syndrome under my hood because the vent would be sealed off from the rest of the bay, not allowing any air to escape besides under the car.

But if I take jtmcinder's idea. I think it will work way better and really solve heat problems.

Well to me I would do the that same thing but that is because I have an oil cooled turbo so I need the air but for you, you could do either option because you have the turbo that allows it. Just remember that the oven under your engine compartment is really not going to get as hot as you might think because the components are really good at keeping heat inside themselves and the heat will escape even if you don't think it will.

Now another thing you would want to consider is to use a turbo blanket and wrap the downpipe. I did that and it helped my temps by another 5-10 degrees (temps taken on the coolant sensor not by a thermometer under the hood) even on the hottest of days and really pushing the car. If you are going to spend the time and money doing the ducting you should make sure you do everything and you will be very happy with the results.

I would also do yourself a favor and send Beau a pm and see what he has to say about his under hood temps. No need to guess if somone has a working unit. I'm sure he would be willing o talk about it.

Beau actually has a video floating around that has him at a track with his temps being recorded on the video in real time. I am also sure though that he will be very happy to help as he has a really good setup that a lot of people have replicated so the results are real and common. Just many ideas to keep in mind when thinking about your options.

 

[AngelOfPassion]

Well to me I would do the that same thing but that is because I have an oil cooled turbo so I need the air but for you, you could do either option because you have the turbo that allows it. Just remember that the oven under your engine compartment is really not going to get as hot as you might think because the components are really good at keeping heat inside themselves and the heat will escape even if you don't think it will.

I agree. However the alternator is right there. Sealing off that part of the bay may fry the thing . Also, my upper intercooler piping is in the general vicinity as well. I feel like blocking the heat from the turbo and manifold from the upper ic piping could help temps in the pipes. My duct would be in between them helping seal off the heat. This is probably one of the minimal benefits from this build but just one more reason to include the turbo/manifold in the duct area.

 

[cait sith]

Fun fact: the old Archer Brothers Talon running a T4 never had a hood vent and it got the crap run out of it in SCCA World Challenge, and furthermore, it got turned into a GT3 24 hour Daytona Eclipse and finished pretty well against M3s, Porsches, and RX-7s which had a lot more chassis development than a tired old DSM.

There has to be better cooling solutions than just throwing a bunch of vents willy nilly on the hood.

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I'm not saying this is the complete solution, but it's proof that vents might not be the right answer.

(Also note the unhooked dipstick! Brave!)

 

[Tyeler18]

I actually have a pretty good solution to venting both the radiator and turbo, while keeping them on seperate ducts. If I had a laptop anymore I'd plot it out, but it'll have to wait for now.

 

[jtmcinder]

Fun fact: the old Archer Brothers Talon running a T4 never had a hood vent....

Would they have been allowed to under the rules? I wouldn't read too much into this unless and until it's known that they could have.

 

[ed1380]

like this?

 

[AngelOfPassion]

Yes that is what I am thinking of doing just maybe without that middle line.

Also, add some ducting around the radiator to force air through it. Also, some ducting under the intercooler and radiator so air can't get out the bottom and maybe it might need some ducting on the top so air can't escape anywhere. I'll know once I get in there.

This is all for future reference. I have to put the turbo, manifold, intercooler, intake pipe, and filter all in first or else none of this will fit right. I have almost all the parts I'm just lacking the time to put them all in.


EDIT:

Here is a top view of the route I am hoping to somehow come up with. I want the alternator and air filter to be separated from the heat and outside the venting area. Unless for some reason the vented area manages to stay cooler than outside the vented area on the alternator side. This will just be a trial to see how it works. I need to do some measuring around the alternator to see possible routes for that part of the vent and dimentions. As well as making dimentions for a "hole" for the intake pipe to go through... this will be a crazy fab up...

I just did this from memory while I am at work so it is way out of scale/position.

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[greengoblin]

What is really going to SUCK is trying to route all the lines in and out of the ducting. IC pipe, intake pipe, oil feed line, oil return line, o2 sensor. Sounds like a massive cluster F&!k to me. Also all those items move since they bolt to the engine while the ducting will be static. WAY over complicated and not worth your time. IMO

Kevin

 

[AngelOfPassion]

Well the o2 sensor won't be too difficult. I am planning on keeping the upper intercooler piping to the outside of the duct area. It's the lines to the turbo and the lower intercooler piping that might be a pain. And as long as I can find something somewhat flexible and non flammible I could use it to keep the lines from hitting against the duct. I was thinking along the lines of the lining on the bottom of your garage door for the intake pipe area. Just so the pipe isn't in contact with the duct. I would just have to find something similiar that isn't flammable/meltable.