Are dyno runs done with the hood open? I keep seeing pictures of car with their hood open when it is running on the dyno. Shiv? If so why?

To keep the car cool. When I went to see my friend's 590hp at the wheels Z28 on the dyno they had the hood open and huge fans there to help keep things at a decent temp. I just dont think that the electric fans could keep up with the heat of full throttle runs.

its for those Ram Air setups! http://www.i-club.com/ubb-files/biggrin.gif
Keith

C'mon, surely there gotta be more response to this. It is important for my personal research.... c'mon techies!

The fans they run at the front of the car, are to try to get some form of moving air into the air intakes, without this the car would starve of oxygen ? it is also to help cool the components as they are put under a lot of stress when on a rolling road. They are usually run with the hood open in the UK as well.

Yeah, it's strictly an airflow thing to try to keep the engine cool. Even with the really big, powerful fans that dyno shops have, if you keep the hood closed the engine won't see the amount of air it will see at normal road speeds. In college I ran a number of different engines on engine dynos, and even with very powerful fans positioned no more than a few feet away the headers would glow red. hehe - it was cool!!

Pat Olsen
'99 Legacy 2.5GT 5 speed sedan

PS - Aren't the Brits so cool with their "rolling roads"? It sounds so much nicer than "chassis dyno".

ROFL http://www.i-club.com/ubb-files/wink.gif

Fans are used at the dyno on a Turbo car to force air over the IC. This is to create at least a minimal efficiency of the IC. The hood is usually open to watch engine externals under high RPM to make sure all is well and sometimes to watch fuel pressure using a gauge while under boost. Yes, airflow will also help to keep the motor and turbo a bit cooler too. The small fans that most dynos I've used are not very effective though. Dynoing in a windtunnel with the hood down to simulate going down the road would be ideal. These conditions would give a better reading of power under true road conditions.

Spraying the IC with Water helps to keep it more effecient while on the dyno also. If you don't, it gets real hot and you loose most of the benefits of having one. Spraying NOS on the IC works the best. I measured 30 more real HP by spraying the IC with NOS on the Dyno on my Supra TT. I haven't tried this with the Scoobie yet. This also works well at the 1/4 mile track just before a run...just don't let the track officials see ya doing it http://www.i-club.com/ubb-files/smile.gif

Mark J.
99' RS Turbo www.subaru.stinsonweb.com (http://www.subaru.stinsonweb.com)
"Real Dyno Charts Posted"

Yes, it's to keep the engine cool. Remember the majority of engine cooling comes from air fed into the grill (and other areas) when the car is moving. On a dyno, obviously, the car is not moving, so it is not getting the normal air cooling. Engine's are designed to run at normal temps at IDLE when the car is not moving. But if the car is sitting still and the engine is running at 5000 rpm, there's going to be considerable heat.