Zzeal Posted April 8, 2010 Share Posted April 8, 2010 You all see the nifty aero article in the newest Grassroots Motorsports? (May'10 issue) It's authored by an aerodynamic engineer with T.R.D. and he recommends some simple, low buck testing techniques, like applying a flow visualization fluid (powered paint, 3 in 1 oil, rubbing alcohol) to see how it streaks at speed. Love to sit down and have a beer with this guy! Steve Quote Link to comment Share on other sites More sharing options...
Mayolives Posted April 8, 2010 Share Posted April 8, 2010 You all see the nifty aero article in the newest Grassroots Motorsports? (May'10 issue) It's authored by an aerodynamic engineer with T.R.D. and he recommends some simple, low buck testing techniques, like applying a flow visualization fluid (powered paint, 3 in 1 oil, rubbing alcohol) to see how it streaks at speed. Love to sit down and have a beer with this guy! Steve Yes, the Grassroots Motorsports article was informative and interesting. The author pointed out some little things like hood mounting pins that "stick up" that add to turbulence and how we would be better served by installing flat ones. A few little aero improvements, added together, can make a big difference in overall in aero improvement. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 8, 2010 Share Posted April 8, 2010 I haven't seen the article, but hood pins don't seem the most cost effective place to look for aero gains. Maybe I just haven't been able to find the cheap ones but a set of traditional hood pins is less than $10/pair, and a pair of aerocatch pins is closer to $150. NRG makes some that are just over $110 per pair. On my car I'll need 8. I can spend $450-$600 on hood pins to follow the advice of the author, or I could buy regular hood pins for $50 including shipping and have another $400 to $550 left for an air dam, a wing, hood vents, materials to make a radiator duct, or any number of things that might have a much greater effect on the car as a whole. I really think the drag created by the hood pins is fairly inconsequential. It might be "low hanging fruit" because it obviously creates unnecessary drag, but what I'd like to see is drag numbers for and without hood pins to back up the assertion that it is a good place to spend the money. It's tough to find GRM on the news stands around here and I dropped my subscription years ago when it started getting more and more fluffy. I hope this article hits the internet at some point so I can read the whole thing, but I'm not impressed with the "get rid of your hood pins" part. Quote Link to comment Share on other sites More sharing options...
260DET Posted April 8, 2010 Share Posted April 8, 2010 The hood pins I used are off a 70's 80's Falcon GT, they are virtually flush with the surface, turn to lock. I bet some USDM Fords used them too. Ebay? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 9, 2010 Share Posted April 9, 2010 Looks like you can get Chinese knockoffs for $49 per pair. That's still a lot of money for hood pins. I'm not sure we got that Falcon GT with hood pins in the US. It's not ringing a bell. Quote Link to comment Share on other sites More sharing options...
260DET Posted April 9, 2010 Share Posted April 9, 2010 Mustang or whatever other GT type car Ford USA were making at the time? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 9, 2010 Share Posted April 9, 2010 Mustang or whatever other GT type car Ford USA were making at the time? I used to race with the Maximum Motorsports guys who all ran Fox body mustangs, I can't remember any of them having hood pins. I guess I wasn't too focused on their hood fasteners, but I did see quite a few of them month after month and year after year, so I would hope that I would pick up on that kind of thing. I wonder if the US version of the car didn't get pins. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted April 9, 2010 Share Posted April 9, 2010 QUOTE:"I really think the drag created by the hood pins is fairly inconsequential" I wasn't suggesting that we dash out and replace our hood pins and after doing so, reap huge, go fast benefits. I would however, consider a better hood pin design when I build another race car. Several small and 'fairly inconsequential" things can add up to a decent gain. I'm using four, aircraft style, push to lock, pins that stick up about an inch or so and wish that I had researched my choice a little better when we built the car a few years ago. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 9, 2010 Share Posted April 9, 2010 I wasn't suggesting that we dash out and replace our hood pins and after doing so, reap huge, go fast benefits. I would however, consider a better hood pin design when I build another race car. Several small and 'fairly inconsequential" things can add up to a decent gain. OK, and I will give you that there may be some benefit there. My guess though is that several small and fairly inconsequential things on a Z will not add up to a decent gain in comparison to another car with better aero. The Z is so poor aerodynamically and the hood so sharp in front I'm just not seeing that making much of any difference. It's too bad that it wasn't tested in the wind tunnel to prove one way or the other. What we can say from the previous testing is that the airflow at the front edge of the hood isn't smooth; just looked at the wind tunnel pics and verified this idea (test 9, 14, 16, 17). The yarn is not flat on the hood at the leading edge, which is no surprise really. So put the hood pins close to the front of the hood and the rear ones right at the back, and the fronts will be in disturbed airflow and the rears will be in the high pressure area at the base of the windshield. That in and of itself could reduce whatever tiny amount of drag there is from hood pins pretty effectively. But even with more traditional placement at the rad core support I just can't see it being a worthwhile thing (to me from my bang for the buck perspective) to concern myself with. I really think that the goal for us road racers should not be so focused on reducing drag, it should be to produce downforce. Focusing on drag in a Z just seems like tilting at windmills, and we have no shortage of power for these lightweight cars to overcome a .005 CD increase in drag. For what it's worth I signed up for a free issue of GRM, so maybe after actually seeing the article I'll have a better idea of what the author said, assuming I get the right one. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted April 9, 2010 Share Posted April 9, 2010 For what it is worth I know some old aircraft guys who spend tens of thousands of dollars having lower profile rounded rivets installed to hold on there body work. Some of them claim up to 50% improved fuel economy. Granted they have thousands of rivets and we have 8-10 pins, just food for thought. Quote Link to comment Share on other sites More sharing options...
Sideways Posted April 9, 2010 Share Posted April 9, 2010 I raise the notion to have a generous fellow HZ member scan these the article and put them up for the rest of us! Quote Link to comment Share on other sites More sharing options...
Mayolives Posted April 10, 2010 Share Posted April 10, 2010 (edited) I raise the notion to have a generous fellow HZ member scan these the article and put them up for the rest of us! The article is a number a pages long with many pictures. I really don't want to gobble up a lot of space here on the web site. Grassroots Motorsports Magazine is a good read and I look forward to it's arrival each month. It's content is aimed at the none sponsored, amateur car racing person with an out of pocket budget. This magazine doesn't deal with the Nascar BS that fills the pages of the typical car racing publication. IMHO, it's well worth the subscription cost and I really enjoy reading it. Edited April 10, 2010 by Mayolives Quote Link to comment Share on other sites More sharing options...
Leon Posted April 10, 2010 Share Posted April 10, 2010 The article is a number a pages long with many pictures. I really don't want to gobble up a lot of space here on the web site. Grassroots Motorsports Magazine is a good read and I look forward to it's arrival each month. It's content is aimed at the none sponsored, amateur car racing person with an out of pocket budget. This magazine doesn't deal with the Nascar BS that fills the pages of the typical car racing publication. IMHO, it's well worth the subscription cost and I really enjoy reading it. I second that notion! GRM has made me drop my R&T subscription, which I have been disinterested in for a while now. It's always a good, informative read (and they love Z's!). Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 14, 2010 Share Posted April 14, 2010 I know we gained 3mph at 140 by ditching that littel BRE-Styled Decklid Spoiler... At 173+mph, I'm thinking Hood Pins may make a difference, especially when they are measuring my speed to three decimal places. It is all a matter of degrees in the form of competition you have chosen to participate. I laugh when people tell me to lighten my car to make it go faster. I put 250# of concrete in the spare tire well on top of a fuel tank full of 16 gallons of water and went 4mph faster than I did without it in there! Didn't have wheel spin problems either... Little things matter. And Matter More the faster you go... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 14, 2010 Share Posted April 14, 2010 At 173+mph, I'm thinking Hood Pins may make a difference, especially when they are measuring my speed to three decimal places. Now THERE is a case where I think worrying about hood pins might be justified. For us guys who aren't limited by the rules and can just add more power, we just don't need to be as concerned with the drag, and unless you've done everything you can to the suspension, engine, and done everything you can to maximize downforce, the time, $$$, and energy spent to reduce hood pin drag could have been better utilized elsewhere. Quote Link to comment Share on other sites More sharing options...
Globerunner513 Posted June 2, 2010 Share Posted June 2, 2010 I haven't read the article, but I wonder if the author is trying to say that the hood pins create more turbulent air as it approaches the windscreen/roof of the car, and perhaps a smoother flow is better? That is to say, the effect on the flow of the air over the car rather than the actual drag that's created. Still, I would imagine any effect would be minimal, until very high speeds like mentioned above. Quote Link to comment Share on other sites More sharing options...
gnosez Posted June 3, 2010 Share Posted June 3, 2010 After all the money gets spent on suspension, engine and aero mods, I vote that the best bang for the buck would be more driver instruction. Quote Link to comment Share on other sites More sharing options...
zgeezer Posted June 3, 2010 Share Posted June 3, 2010 The hood pins I used are off a 70's 80's Falcon GT, they are virtually flush with the surface, turn to lock. I bet some USDM Fords used them too. Ebay? Yep, Ford hung them on 69-71 or so big block mustangs: Think Shelby 500, but Ford has them on non Shelby Mustangs also. They look good. I think they were part of a GT styling level. G Quote Link to comment Share on other sites More sharing options...
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