Hood louvers

[smelfi]

I'm close to finishing up preliminary body work on my 77 MGB 302 conversion in preparation for sending it of for final body work and paint and I'm wondering if I should have the hood louvered.
Are hood louvers essential on a 302 conversion? In the photo gallery here I've seen some with none, some with a few, and some with quite a few.
I know they should be up near the cowl area but do you need to consider where to position them so rain/wash water doesn't drip through and onto water sensitive components?
I'll have an early mustang radiator, a shroud, and puller fan. I live in central Ohio where it doesn't get extremely hot.

Steve Melfi

[mgb260]

Louvers will help but, it is more important to have holes in your inner fenders for evacuating heat. Do you have through the fender headers? If not put louvers there.  There is a guy that sells louver panels on Ebay pretty reasonably.

[smelfi]

Jim,

Yes, I've got through the fender headers.
I'm going to install small adjustable appliance feet in the channel that runs around the sides and back of the engine bay in order to keep the edge of my hood aligned horizontally with the fenders and cowl edges. I could remove the rubber seal that goes around the upper area of the channel in order to let some heat escape.

[rficalora]

You can also trim off the front edge of the channel in the area between the hood hinges like Bill Guzman did and Paul Schils & I copied.  

As for the louvers, I say go for it... The more air you can let out, the better.  Especially when idling when the header holes don't help.  To keep water out pick up some magnetic sign material at your local sign shop.  Cut it to the shape you want and keep it rolled up in the trunk for a rainy day.

Rob

[ex-tyke]

...To keep water out pick up some magnetic sign material

That's great unless you have an aluminum hood!

I've positioned my louvres over the exhaust and valve cover areas and those areas do see some water but not enough to cause any issues.

[BlownMGB-V8]

Or... you can cut a big honkin hole in the hood for the blower to go through!

JB

[Moderator]

Are hood louvers essential on a 302 conversion?

Clearly not, since many 302 conversion owners don't have them.

I know they should be up near the cowl area...

If you want the louvers to be most effective when the car is in motion, they should NOT be in the cowl area. The closer to the rear of the radiator the better. Air flows from high pressure to low... At speed, the area directly in front of the windshield and above the cowl vent is a relatively high-pressure area.  That's precisely why the cowl vent works and air rushes through it and into the cabin even when the top and windows are up.

[tr8todd]

They are located directly over the exhaust manifolds on a TR8 and you can definitely feel the heat coming up thru them when the car is standing still.  They must really help when the car is moving.  Bear in mind that the frontal slope of a TR8 is severe and not much air passes into the engine bay.

[DiDueColpi]

Steve,
I want to reinforce the statement that Curtis made. Louvers should not be in the cowl area.
The roughly 1/4 to 1/3rd of hood area in front of the windshield is under pressure at speed. And a louver in this area will flood the engine bay with air when it actually needs to be evacuated. Jacking the rear of the hood up has the same effect. It forces air in when it desperately needs to get out. If you look at the engine bay you see a large opening, the radiator, letting air in. And with a V8 in there, precious little space for it to escape. Anything that can be done to facilitate the air egress will help.
Louvers are best at the rear area of the radiator near the front 1/3rd of the hood. But this causes a problem with water getting onto your ignition system. Also, and anyone who has had properly working louvers will tell you, when they evacuate the air from the engine bay they bring everything with it. Road debris, fuel standoff from the carb, bugs, any leaks from the engine, water spray from the front tires all end up on the windshield.
So one of the best ways to allow  airflow through the engine bay is to put in inner fender vents. These can be connected to an outer vent in front of the doors (an excellent low pressure area) or just dumped into the wheel well.
A front air dam is also a big help to the cooling of the engine bay. It doesn't, as many think, force more air into the radiator. It causes a low pressure area under the car that pulls air out of the engine bay. A side benefit is it pulls air in through the wheels cooling your brakes as well.
At the end of it all though, louvers just plain look good. l'd put them in but block them off from underneath.

Hope thats helpfull
Cheers
Fred

[Preform Resources]

Thank you Fred, for explaining one of the benefits of a front air dam that escapes most people,cept for the sebring style
they will still have the same issues as a stock front valance, only with brake ducts.
Dave Craddock

[djw090]

Agreed it is getting the hot air out that is important. Some years ago I saw the Nicholson C ar Silverstone. It had an interesting duct behind the radiator exiting through the bonnet. I will hunt through my photos at home on Friday as we have a public holiday for the wedding.


Picture now attached. That type of duct significantly helps air flow through the rad when the car is moving. When standing there is always the fan.

[Preform Resources]

David, that is a typical bespoke race car method of radiator air exiting, some times you can't run a setup like that ,like in SCCA production cars ,you can't put holes or ducts in you hood unless it came that way. Bruce McLaren found  that when he bought the old Penske Zerex spl. that in testing ,the nose was billowing up and down at speed, so he pulled in and cut an opening in the top of the nose, relieving the air pressure, improving the cooling and aerodynamics as well. The early McLaren can am cars are evidence of this.
Dave Craddock

[johnny wells]

David,

Do you have any more pictures of the Nicholson C?

Would love a closer look.

Thanks,

Johnny

[djw090]

Johnny, sorry only that one. The picture was taken at the Coys Historic Festival at Silverstone in either 1996 or 1997.

Nicholson also worked on Bs and one of his Bs was driven by none other than a Mr Senna in his early days. Senna also married Nicholson's daughter.

[johnny wells]

Thanks David.  I did do an Internet search and came up with a little information.  I was surprised to learn how influential Bill Nicholson was with the B and the C.  What a great look with those subtle fender flares, and the rear arch is just right.  I wonder where that car is today.  Johnny  

[djw090]

Johnny, the Coys meeting at Silverstone was a prestigeous general historic meeting rather than an MG meeting. I havn't been to such an event for some years so I don't know if the car is still active in that field.  However, I have been to the main MGCC event at Silverstone most years since and Nicholson C has not been about.

[RickyDo]

Hi Guys, first time post here....

Recently picked up a 1980 B with a '69 Chevy 350 LS9 motor in it.  I did not do the conversion. See photo attached

As I am sure some of you know Chevy 350's run hot and mine was no exception.

Was often over the 220 degree mark at idle.  

The guy that did the conversion cut two holes in the bonnet approx 4 wide by  8  inches long next to the hood scoop and covered them with chrome vents.

I was able to keep the engine bay much cooler by attaching (4) 92mm 2000 rpm 12v computer case fans to the underside of the vents and wire them up to a rocker switch on my dash.  The four fans do a great job pulling the heat out of the engine bay

The engine itself consistently runs 20-30 degrees cooler then it did with out the fans.

[Moderator]

Welcome to the BritishV8 forum, Ricky!  Looks like you've got a nice car there. I'd be very interested to see more photos and read more about it.

[J Man]

If you go with the louvers and want them punched, let me know. I have a friend in Columbus that might be able to do it, if he can't I know he will be able to get me a name of someone that can.

It would be best to PM me if you want me to ask him.

[roverman]

OEM. 67' bbc. Vette with cowl induction hood, does it all. Hot air exit for radiator and cooler air for the carb. Available in aftermarket f-glass ?   My turn, where do I research for rear mounted radiator designs ? Thanks, roverman.

[DiDueColpi]

At the back of the car!