*Boostwerks*

I'm trying to figure out the best method for me to vent the engine compartment out through my hood. I'm running a turbocharged B16, and can only fit a half core radiator. My engine bay (CRX) along with all the turbocharging components and engine swap is extremly cramped and will surely be a high pressure zone.

I'm mainly curious if the air right infront of the windsheild will be a low or high pressure zone in relationship to the engine bay. I'm thinking about installing a STI style hood scoop only in reverse, but without a wind tunnel I'm not really sure how effective it will be.

Any opinions?

I thought about installing some naca ducts only in reverse, but have found that they are very ineffective in a reverse orientation. I also thought about doing some EVO style hood cut outs, but don't really like the look of openings in the hood. However, if the cutouts are more effective I might go with them. function over form in this case.

Thanks,
Bryson

2fast4u831

I suppose the reverse scoop should work. How about propping the hood?

fireant

The first thing you should do is get a cheapo digital thermometer to put under the hood, if you dont already have some kind of gadget that tells you your exact water and air temps.

Then you can start with the suggested hood prop mod. Put some washers in there and see if it helps.

If not, you've spent about $3-$15 and have a baseline test temp to work from.

*Boostwerks*

Thats exactly what I was thinking about doing. I'm currently wondering where the best place might be to put the sender, and what exactly the readings would be telling me.

What I'm mainly trying to acheive is a low resistance of flow through the radiator and out of the engine bay. The secondary goal is to remove the hot air created by the turbo components.

I may just have to do some testing next season, keep a close eye on coolant temps and mod as neccasary. I'm just willing to bet that I'm going to run into heat issues due to the fact that our new track is f'n huge.

jlude90

i've heard of 15* differences in IATs from the washer trick

heard of, but it was a reliable source if i'm remembering properly

are you doing any shrouding around the openings where there is no radiator?

descartesfool

Put the external type temperature sensor of a dual internal/external type thermometer with min/max readings behind the radiator clear of the fan blades. If you make a change that allows more airflow through the radiator, then the air that has gone through the radiator will have a lower temperature. It is fluid temperature loss through the radiator that does almost all the engine cooling. You of course care about the differential in temperature between the outside air and the radiator exhaust at the same engine load, so just subtract the difference between the radiator exit and outside air temperatures. If the difference gets smaller, you have made an improvement. Compare this with reading on your water temperature gauge. Best thing would be to mount a video camera that sees the water temp and engine bay and outside temps on the digital thermometer taped to your dash all at the same time. Do 5 laps at least to get car up to full temp.

Lo-Buck EF

run with the hood off

sander

This is excellent advice, and an excellent test plan.

This also sounds possibly a little odd, but if it is a race car and your fuel type is unlimited, maybe consider different fuel types, there are excellent cooling benefits to be had with some of the lower btu rated fuels (ethanol, methanol). Obviously your fuel system will need to reflect this change as well, if this is even an option to begin with.

Heat is a serious problem with these full race radiators in CRX's. I had tuned a car or two with these set ups (more street cars, none were track cars) with pump fuel, and they were OK, but got hot fast enough to make me see it as a potential problem at a track day.

SHG_Mike

Also a suggestion, get an oil cooler, you'd be surprised how much the oil cools the motor, compared to the water

sander

Also an excellent idea, The old air cooled Porsche engines gained a lot of their operating cooling from the oil coolers as opposed to the enormous fan and crazy ducting systems they had. 930 turbo's in particular.

JuanTushag

I have done a lot of work on reducing under hood temps and engine cooling on the honda civic EG and CRX. The biggest problems I found were this, (it may get off track for a second,,, but i get to hood venting)

1. air quite easily goes around the radiator, not necessarily through it . Especially with a half radiator. Very little ( relatively ) goes through the radiator from "ram air"

2. Then the large mass of air "backs up" behind the radiator. This further reduces the likleyhood that air will travel through the radiator.

3. The hood then becomes a large "lift" device . Even if you had 1/4 psi differential of higher pressure air below the hood,,,, it adds up to some pretty high "up-force"

I had problems on 3 different Honda challenge cars . Even when switching to much bigger radiators , they didnt give that much better cooling So i created a radiator shroud that forced any incoming air to go through the radiator. This helped in 2 different ways , it forced air to go through the radiator , and kept pressures behind the radiator lower ( much less air going through the front ), That differential in pressure is what keeps strong flow THROUGH the radiator .

Ok now Im in H2 . where we can vent the hood. I chose to vent right above the header area. I believe that is the most likely place for a low pressure area. It also happens to be right behind my radiator ,,,,,now even lower presssure behind the radiator,,,,,which means even more flow,,,,,yaaaa

I was just going to cut some slots in the hood of my car , I have a friend at Afterhours Performance in Torrance CA. He makes these hood vent inserts . I have used 2 of them so far

Ok let me see , I just did a crx hood and radiator schroud , let me find the pics

OH, i almost forgot , i firmly believe there is high pressure at the base of the windshield/hood

R

JuanTushag

ok here is the hood vent. I have used this on my Civic H2 race car at Buttonwillow in 104 degree temps

JuanTushag

here is a pic of the shroud. it is very simple ( so are my fiberglassing skills ) I made it with a plug ( the opposite of a mold ) I did this in a few evenings . the results are tremendous. I dont run an oil cooler on my civic, i use the GSR oil/water heat exchanger. ( this CRX has an oil cooler) My temps are always 185. even with the extra burden of the heat exchanger

Pompiuses

Got any more up close pictures of the radiator shroud? I can't really see where the air flows.

JuanTushag

ya here is one from the front. I have made a previous one out of thin aluminum in an afternoon, that one worked well too. This one was made on top of the radiator ,,, I made a plug the shape of the shroud , then placed it on the radiator ( covered the radiator in plastic ) then glassed over it . In the end ot fits perfectly , just about air tight to the radiator. I am giving the mold/plug to a friend of mine that can actually lay fiberglass , he is the guy that made the hood inserts and is going to make a few for the Honda Challenge guys down here .


Also here is another of the hood that shows more detail

unrealwrc

Great job on the shroud and hood.

The hood should generate alittle extra downforce as well as the cooling and is something i wanted to do to my car for awhile now.

*Boostwerks*

Sorry for the late reply, but that hood scoop is pretty much exactly what I was thinking. Any details as to who makes it? I Also wanted to mention that I do have a 6x10" oil cooler, but with the tiny full-race radiator and being turbo'd I'm still going to want all the cooling I can get. Here's a pic of my version of a shroud:

Lo-Buck EF

my exact thoughts and exactly what i have been wanting to do on my H2 EF. i used to run with the back of the hood up to try to get some heat out and keep the air moving but i wann't convinced of the results.

*Boostwerks*

Yeah, it's always been my understanding that the pressure at the bottom of the windsheild is fairly high, which would result in very little or even reversed flow with a tilted hood. Not exactly what we're after.

jlude90

but if you tilt the hood doesn't it create a low pressure zone at the base of the windshield/behind the hood

JuanTushag

That shroud looks great. I got the hood vent from this place

http://www.afterhoursautomotive.com/

its a really clean install. the owner of the shop is Brian Kono. he makes these himself.

On the CRX i moved the oil cooler up behind the headlight , laying flat and venting through the hood. ( thats what the blue tape and marks are for the vents to be cut for the oil cooler )

In the first pic of the CRX I think you can see it ( oil cooler ducting still being fabbed up ) Brian is making the duct work for that out of aluminum ,, ill try to post a better pic.


R

JuanTushag

here is the one that shows the oil cooler,,, i will try to get a bigger pic

Tyson

cool stuff renan.

*Boostwerks*

Awsome. How much would he charge for one? I havn't been able to find one like that.

I chose to put my oil cooler right infront of the drivers side tire. I might build an aluminum cover for it to protect it from rocks picked up by the tire. I'm hoping there's enough air flow at speed in that area that my intake doesn't rob flow from the cooler.

Mr.E.G.

very nice.

I preach about this regularly but people always want to over complicate things and they come up with these aero systems that are based more on hope than anything else.

it really is not that complicated and the what you have here proves that. completely seal the radiator from the rest of the bay with ducting in and out. venting it through the hood is a no brainer compared to the "sort of kind of hopefully maybe it will work" plan of venting via a hood that is raised near the cowl. some cars build high pressure areas near the base of the windshield and the washer method will not work in that case.

many people have a hard time imagining how the air will flow. I recommend imagining that the car is submerged in water. the same basic principles apply (that's a bit of a watered down explanation... no pun intended) and with the washer hood riser method you can clearly imagine how water would potentially spill in from the side seams of the hood (on account of the big crack you made) and how the airflow or water flow would be tricky to contain. a complete ducting setup takes a lot of the guess work out of it.

follow the simple parameters of having the inlet sit in a high pressure zone, have the duct work start relatively small in comparison to the size of the radiator to keep the air flow moving quickly into the ducting. next, have the ductwork expand to the size of the radiator which allows the air to slow down and linger just a moment longer around the radiator to effectively exchange the heat. lastly have it get narrow again to get the velocity back up at the point where it reenters the airflow. make sure that the it vents to an area if relatively lower pressure. there are some aspects of aerodynamics that are very confusing but this really should not be one of them.

should anyone need some inspiration, take a look at an aston martin dbr9 or the corvette c6r. there are tons of pics of each floating around the internet and you can clearly see way their radiator ducting works. it's quite simplistic with the exception of the dbr9's oil cooler which sits in the "nostril" of the car and it might confuse the untrained eye. if anyone wants some pics of these cars without some of their body work to get a clear idea of how they are setup in that regard, just PM me. I have literally thousands of pictures of these two cars saved to my computer.

I am collaborating with another honda-tech member to create some aero parts for his eg and I am working on something very similar to your design but with a steeper radiator exhaust duct (more closely related to the center radiator ducting of the 911 gt3rsr) on account of his turbo manifold.

far too often this goes unmentioned, but an added benefit of isolating the radiator airflow from the rest of the engine bay is that you no longer have to rely on the bottom of your engine bay being open as a source of getting the heat out of the engine bay. This frees you up to completely block this off with an under body panel or to extend your splitter back under the engine bay. this will 'clean up" much of the under body airflow and enable you to really get creative with your aero options if you should choose to do so.

if you do that, I think you should always have a separate vent on the hood by which the ambient under hood air can vent to. it does not necessarily need to be fed a supply of fresh air and you needn't worry about ducting for this. simply some holes so that the hot air can get out. you can get all fancy with some push pull fans and all of that but i think once you remove the radiator airflow from the engine bay you will find that you are good to go.