JMortensen

As far as boar hunting goes my understanding is that you're usually at pretty close range when you shoot. Open sights might be better than a scope. Sometimes when you use a scope up close all you see is fur and it's hard to aim. I think this is particularly a problem when you're in close and whatever it is you're hunting is trying to kill you. That's why you don't see too many people hunting cape buffalo with a 10x scope... For what it's worth I wouldn't hesitate to use a .270 or a 30-06.

Sounds like a bad booster and master to me, basically you're leaning out the engine really bad when you step on the brakes, because it's sucking air through the brake booster diaphragm. You can pull the hose off of the booster and suck on it, and if it doesn't hold vacuum then you know it's bad. The master should never lose fluid. Pull it off and look inside the booster. I bet you find that it's got a bunch of fluid inside. The only other option for loss of fluid is that you have a leaky fitting or a bad caliper or wheel cylinder.

The fender vents on the blue car are connected to some holes in the inner fenderwell, so they basically take air from the engine compartment and extract it to the fender. The fender vents on the top of the fenderwell take air from the fenderwell and extract it through the top of the fender. I think both ideas could be used simultaneously, maybe in addition to that you could have an airdam which has a lip in front of the front tire as well, which would suck air out of the fenderwells in that direction too.

Downforce in the rear. Front end got light.

Are the holes in the core support plugged or open?

Sounds like a good deal to me. I think I paid $607 for the welder, a helmet, and a pair of gloves. If you want a cart, go get the HF one. It fits the welder much better than the Miller cart.

I still think you guys are wrong about the air under the hood. If NASCAR can get neg pressure under the hood, then we can. NASCAR cars are very basic in terms of shape, previous to last month's release of the COT they didn't have splitters or anything else. No undertrays, no nothing. All they do is get the nose of the car ON THE GROUND, and use the shape of the car to extract air from under the hood. I see no fundamental reason why we can't do the same thing.

This is due to the location of the wake or "pressure drag" behind the car. The spoiler deflects air upward causing some downforce and that also pushes the wake upward as well. Without the spoiler the wake is directly behind the car. With the spoiler the wake is moved further away from the body and higher up and so it can't "suck the back of the car" as well. This link talks about pressure drag in aeronautics terms: http://selair.selkirk.bc.ca/aerodynamics1/drag/Page2.htm There was quite a bit of discussion about changing the location of the wake and how that could reduce drag on these threads: http://forums.hybridz.org/showthread.php?t=117165 http://forums.hybridz.org/showthread.php?t=115294

You could draw them up and have them made like he did, or you could buy a new LSD for $500. I don't think there are any replacement parts available. At least the people who have gone looking for them can't seem to find them.

Any pics? Were the holes in the core support open?

The wind tunnel operator thought the rear diffuser was a waste of time, not Mike Kelly. It was stated that bigger gains could be had working on the top of the car than the bottom. Here's a list of things that I would like to see in the next test. I don't expect that this will all happen, but these are suggestions: 1. The car lower to the ground 2. The airdam much lower to the ground, maybe 2" from ground level or so 3. Sealed and sloped airbox from the airdam to the core support 4. Bigger vents in hood, with a trip strip in front of the vents 5. Large single plane wing on back, with and without Gurney flap 6. Test with splitter vs without to see the difference the lip makes 7. Test with window nets, both the "strap style" and the fine mesh style 8. Flare/airdam combo which covers the leading edge of front and rear tires and preferrably sticks out at least 2 or 3 inches past the tires on each side 9. Holes in bottom of rear window 10 Holes in top of rear window

http://www.amazon.com/Tune-Win-Carroll-Smith/dp/0879380713/ref=pd_bbs_sr_1/103-6497924-6233420?ie=UTF8&s=books&qid=1179156406&sr=8-1 I haven't read it in a while, but it has do's and dont's for duct shapes, and I think it talks about pressures inside ducts as well.

No, I think that COULD BE what happens. And the point with the Bernoulli effect is that air doesn't necessarily have to flow out of the vents because of pressure. But when the top area between the core support and the hood is left open, and all the holes in the core support are left open I think it's very difficult if not impossible to obtain a negative pressure under the hood.

Exactly. The book Tune to Win has some more detailed info on flow and radiators, how to shape them so that you get good flow across the entire radiator, etc. if you're interested Bob. That's exactly what I would expect. More air trapped under the hood, not getting sucked out by the Bernoulli Principle. So are you agreeing with me there, or did I miss something? Might be fodder for the next testing session. I'd be REALLY interested to see the results of that particular item.

At this point I think THE KEY to getting underhood negative pressure is the box. Everything that you've done to limit air from going where you don't want it to go has been successful, but there seems to be a resistance to the box idea which I don't understand. The circle track article states: So they're saying that BOTH of the boxes that they used sealed the nosepiece to the radiator, but this version of the box allows for negative pressure directly above it. Just that small increase in available space for the neg pressure to act upon change the downforce by 180 lbs. That's not counting the rest of the hood! By the way, the yarn only shows where the air is going, not what the pressure difference above and below the hood is. I know that doesn't sound like it makes a lot of sense, but to put it in other terms, Bernoulli's Principle will allow you to evacuate the crankcase and create a strong vacuum by attaching it via a hose to the pressurized exhaust. You would think on the face of it that the pressure under the hood HAS to be higher for the yarn to show air coming OUT of the hood. In fact this is not the case. Just like the crankcase example, air flowing past the hood vent, especially one that is properly designed, will suck air out from under the hood even if there is negative pressure under the hood and positive pressure over it. I am not going to press this particular point any further after this post unless a new angle is brought into the discussion. I don't want to wear you guys out right off the bat, and there are a lot more things to talk about than just this.

I think I'll have to disagree with Bob on that point then. I don't think you'd see so many race cars from so many different classes doing the same thing if there were no point. The opening to the box I'm suggesting could be whatever size you want to get a very small frontal opening. This is very similar to the point you guys proved about sealing the air dam to the core support. That prevents air from spilling out UNDER the radiator. The box prevents air from spilling out OVER the radiator and through the holes in the core support. And if you have a LOT less air in the engine compartment you might just make a low(er) pressure area under the hood, which translates to more downforce.

I'm not sure you're getting the point of the box. It isn't only there to limit the amount of air coming into the radiator. That is it's less important purpose. It's more important purpose is to eliminate the pressure from the underside of the hood. And this ties in with the other question as well, about sealing the core support to the hood. If you have positive pressure inside the nose of the car and have not sealed the core support to the hood, then presumably just as the air can go down underneath the airdam under the car, the air can also go OVER the rad core support and through the holes in the core support as well. This will increase the amount of pressure under the hood. If one were to seal the core support to the hood, then air would have to go through the radiator or holes in the core support to get into the engine compartment where it would be either evacuated by the vents or by traveling underneath the car. But in the area between the hood front and the core support, there would be a large pressurized area exerting force in all directions. If one were to do the box structure and seal the hood to the grill area so that all the air that went into the box went through the radiator, then you'd get a couple of benefits. You guys already showed that cutting down the amount of air is beneficial. In addition though, you'd cut down the size of the pressurized area in the front of the car. In fact, you could probably get negative pressure in the front hood area above the box. Negative pressure under the hood, coupled with the pressure of the air being diverted over the hood = more downforce, and that's why you see so many race cars using that type of radiator duct. If memory serves I think preith has this type of setup on his car, with a sealed box and a much smaller inlet hole for the radiator. Here is a link that describes what I'm talking about from a circle track magazine: http://www.circletrack.com/techarticles/0304_aerodynamics_tech_definitions/ The magazine article has some flaws, but the article estimates a 180 lb downforce gain from this type of box. It also talks about using a wide airdam to suck air out of the fenderwells.

What were his comments?