Engine Compartment Venting

[n49racer]

OK. I've searched an found nothing. Last year we had a small oil mist explosion and fire. With the twin turbos we also have a lot of under hood heat. I'm wondering, on a our closed engine compartment we have the trunk lid louvered to vent air from the engine area. What are the thoughts on adding small vents at the front of the compartment to let some air in to get some of the hot air out?   

Ok Batter Up

[SPARKY]

We do not have turbos-- but we make sure we vent so that we dont burn plug wires off and if we ever have a fire we are sure trying to pull the flames away from the fuel

[n49racer]

Thanks Sparky. There's a lot of heat in there, the problem might come from having our fuel tank at the rear.

Ted

[kiwi belly tank]

For a start, blanket the turbo's & hot pipes so the heat goes out the pipe. This guy can build you custom stuff for that & it won't cost you an arm & a leg. It's so good that it feels like warm laundry with your hand on the turbo after a run. Turbo Performance Products. 208-251-9141.
Putting fresh air into a fire at speed will feed it oxygen & turn it into a monster.
Build a cheap fire warning system using furnace snap switches hooked up to a warning light, works bitchin!
  Sid.

[n49racer]

Thanks Sid  I'll take a look. We do have blankets and have everything wrapped.  It still gets pretty warm in there. I was just thinking of venting some of the hot air.

Ted

[MAYOMAN]

We had similar concerns on the Honda Hawk streamliner. It was a turbocharged twin engine bike and we used NACA ducts, one on each side to supply cooling air to each 750cc engine. 4 ducts for cooling. You need to allow the air to flow through the engine compartment and exhaust from the vehicle.

[MAYOMAN]

We also used a NACA duct to directly feed air to the turbocharger on the top of the bike.

[MAYOMAN]

Here are a couple of better views of the turbo insulation and the air venting inside the engine bay.

[n49racer]

Thanks Mayoman
I also had a talk with Don Ferguson and thank him again if he's on the forum. He too said he had to run scoops at the front of the engine compartment with reversed NACA ducts at the rear of the streamliner. He said without the venting, all the zip ties melted holding his spark plug wires. Just 1 more thin to do before SpeedWeek.

ted

[Rex Schimmer]

I am always amazed that people run NACA ducts backwards to vent air from the inside of a car. They don't work backwards! Kind of goes with an old NASCAR saying, "If Petty won a race dragging a dead cow across the finish line, there wouldn't be a cow in the country come the next race!" Monkey see, monkey do. Take some time to see exactly what makes a NACA duct work then it becomes obvious that they don't work backwards.

Rex

[WOODY@DDLLC]

Rex, any hole will "leak"!  :x But some "leaks" are more efficient than others! 
Properly designed you can produce some usable thrust with the added heat! 
BUB7 does this - ask Denis Manning! 

[Eddieschopshop]

I use a combination of different facing louvers to allow some air to chase down along side the exhaust through the engine bay.  Gets a little cooling and in theory it actually helps the aero.  By stripping away the boundary layer in one place and filling in another.  Pretty hard to prove this though..

[SPARKY]

but it sounds so cool when one explains this "stuff" to others 

[MAYOMAN]

I was going to reply about running the NACA ducts backwards, but Rex and Woody beat me to it. The PDF drawing of the Honda Hawk illustrates one solution which also provides good parachute deployment as well. The BUB streamliner uses similar strategy. Anyhow, the NACA duct is an INLET duct and the aerodynamic principle does not working in reverse.

[Bratfink]

Take air in the vehicle at the stagnation region. Take air out the car at areas of high velocity.

The trick is finding the right areas