AutoX hood alterations.

[jtmcinder]

And before anyone brings it up, since the differences between Evo Xs and DSMs seems to be an issue these days, please note that Evo Xs use a completely different air-flow through the engine bay, so don't even think about adding a NACA duct anywhere on the hood (other than over the air-filter, maybe). The NACA duct on an Evo X is to drive air DOWN across the turbo (which is on the back of the engine on an Evo X) and then out the bottom of the car. A DSM really doesn't want any air coming in through the hood.

 

[black_gst]

Gotta love those high timing belt temps... I always kinda guessed a vent in that location would held circulate air under the hood, is that a correct assumption?

you dont want to circulate air under the hood, you want to extract hot air.

lots of air comes through the radiator, redirecting that air through the hood and passing by the exhaust manifold is what you want to do.

directing more air in just creates more drag and even lift

 

[spyderdrifter]

Sweet. Got the direction I needed.

 

[eclipsegsx1736]

Beau, you really need to upload a bunch of photos of your car to your gallery so people can quickly view them for reference (like me).

I saw this thread of yours some time ago. Amazing work you did. Once I build my road race engine and start getting the body ready, I'll be looking to build one of these as well.

I am looking into doing my setup like what Beau and jtmcinder have done there's. I love Beau's radiator duct setup. Looks amazing, like it came from the factory almost (my opinion).

Thanks guys! I do need to take some better pictures soon. There are a few pictures and some more info in my build thread for this car:

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

As jtmcinder said, airflow over the vent extracts air. Also, adding a lip in front of the vent will help create a lower pressure zone directly behind the lip and greatly improve this effect. You'll see this on the OEM Evo hood vent, although their design is pretty conservative as anything more extreme would probably look ugly for an OEM car.

Beau

 

[snowborder714]

Here's my setup, which seems to be setup more for road racing than autox per jtoby's info.
http://www.dsmtuners.com/forums/app...-hood-vent-installation-cf-hood-painting.html

 

[spyderdrifter]

Thanks guys! I do need to take some better pictures soon. There are a few pictures and some more info in my build thread for this car:

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

As jtmcinder said, airflow over the vent extracts air. Also, adding a lip in front of the vent will help create a lower pressure zone directly behind the lip and greatly improve this effect. You'll see this on the OEM Evo hood vent, although their design is pretty conservative as anything more extreme would probably look ugly for an OEM car.

Beau

I know you don't have a freelancer banner, and this isn't a request to buy, yet, so I hope I don't get any rules thrown at me, but do you build the radiator ducts for sale? If so, I think that'd be a good quality product for those of us that race, or plan to race.

 

[jtmcinder]

I'm not a mod and I'm not great on rules, but did you consider the PM button instead of Post Quick Reply? I know I did (in this case, at least).

 

[rlacasse1]

As requested: you're wrong. When the car is moving, air moving across the hood creates a low-pressure zone that pulls air out. (Reading up on the difference between static and dynamic air pressure is useful here.) Also, when the car is sitting still, that location is great for having the air pulled in by the fans and come out after crossing the turbo. I found that I didn't have to get out and open the hood between runs with this vent. After yanking the AC, it's very easy to get the fans to run on high when sitting in grid: just push the button that used to turn on the AC.

Right, I know that is what happens when air is crossing the hood. And it's been awhile since I've been up close to a 2g. But where the bump meets the hood isn't there a change in angle of the skin on the hood? And if there were a vent there, air would just want to enter it? As the air would not change directions unless forced to?

Well, I guess maybe a louvred vent would work, I was thinking about more of a mesh though for some reason.

But yeah, go ahead and explain that to me.

 

[jtmcinder]

Well, yes, if you put a forward-facing scoop on the bump over the timing belt, it would let air in. But why anyone would even consider doing such is beyond me ... and I'm a psychologist.

A louver on an opening in a high-pressure area is a lousy way to evacuate air. Much better to use a low-pressure area, such as where the vent was on Cinder than rely on such tricks.

 

[rlacasse1]

Right.

But isn't that place a little higher pressure than the rest of the hood? It seems to me like it would be. Which makes it an unattractive place for a vent.

 

[jtmcinder]

I'm not sure what place you're talking about, but smack-dab in the center of the hood was the lowest pressure I found when testing. That it also happened to be two-thirds over the exhaust manifold and one-third over the front part of the head iced it - as it were - as to where I put my vent.

But don't take my word for it. Do your own testing. The easiest way to measure relative pressure cheaply is by using the gizmo that shows you if your radon system is working. Costs about $3 to make.

 

[rlacasse1]

I was talking about the bump. That's what I meant by "that place". Not where you have your vent. I see yours as being very functional.

I was talking about putting a vent on the front side of the bump.

 

[snowborder714]

It would be pointless. Period.

 

[rlacasse1]

Right! Agreed!

As requested: you're wrong. When the car is moving, air moving across the hood creates a low-pressure zone that pulls air out. (Reading up on the difference between static and dynamic air pressure is useful here.) Also, when the car is sitting still, that location is great for having the air pulled in by the fans and come out after crossing the turbo. I found that I didn't have to get out and open the hood between runs with this vent. After yanking the AC, it's very easy to get the fans to run on high when sitting in grid: just push the button that used to turn on the AC.

I'm trying to figure out why the part in bold was said. Although, I the idea of what to use as a vent was a little mixed up in my head.

 

[jtmcinder]

Why was that said? Because you said "correct me if I'm wrong" and you were wrong and I was correcting you.

 

[rlacasse1]

Well no shit. Care to explain why it was wrong?

And just so you know, in the post you were refering to with that comment I was talking about a vent on the front side of the bump, not where you have it.

 

[spyderdrifter]

I'm not a mod and I'm not great on rules, but did you consider the PM button instead of Post Quick Reply? I know I did (in this case, at least).

Really didn't even think about it, Was at work rebulding a blackhawk tail pylon, so no. I'll keep that in mind for next time....

 

[ulitka]

This VIS hood works very well for me. No longer need to keep the hood open between runs.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[spyderdrifter]

That is a nice hood.

 

[xxNocturnalxx]

1" hood spacers can be had for cheap or made. I currently have them on my Scion. The Mitsu will be getting them soon as well.

 

[LandoAWD]

For spacing the back of the hood? Non-functional. Tuft tests exist on this forum.

 

[spyderdrifter]

Uh, did someone delete a few posts from here¿

 

[LandoAWD]

Yes, and rightfully so.

 

[Diamond Star Werks]

Well no shit. Care to explain why it was wrong?

And just so you know, in the post you were refering to with that comment I was talking about a vent on the front side of the bump, not where you have it.

It is a bad idea because air would enter pass by your timing belt and escape through the bottom of your car.
Creating lift and ineffectively cooling anything important that needs cooling.

If you was thinking it would escape through the back of the hood you are wrong.

 

[GSTurbo1]

I did the hood spacer, we verified a 20' temp drop after on run with the spacers installed. They work great for me

People hate on the spacers because they are 1/100th of the price a vented hood will cost... and by all means the coolest dsm has the most money in it.