139 replies to this topic

[FTodaro]

How much horse power advantage is it to debur the plunge cut?

 

Oh wait that was the other big speculative argument we had on line.

 

Lets turn it in into political issue. "there were weapons of mass destruction" justifying our invasion.

 

Wait, if you see it on the internet it must be true.

 

Lets get some wind tunnel time and answer all these questions so everyone will be at the same disadvantage or advantage, depending on what the tests show. Unless someone is arguing that one model will get more advantage or disadvantage and then we go into parity debate mode on the "parity aspects of taping your inlet screens"

 

Now that is deep.

[Ron Alan]

How much horse power advantage is it to debur the plunge cut?
 

 
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I realize it is water under the bridge at this point but "debur" is far from an accurate description of why heads were found non-compliant.

[Caveman-kwebb99]

I realize it is water under the bridge at this point but "debur" is far from an accurate description of why heads were found non-compliant.

 

the accurate description your looking for is 95% were non complaint, wonder how many have changed their heads...

[Bench Racer]

Let's do the license plate first. Among states it would be a parity issue. Some states require front plate, some do not require plate. The front plate holder is generally dealer installed.

 

Brick or not, I'd suggest the grill blocked below the hood is because more air to radiator is not required and it helps areo. Same for each side on the second opening down and same for the center of the third opening down and the same each side on the bottom opening.

[Bench Racer]

It was legal.. the rule came in after that and because of that!   Thanks for reminding me.. One of my favorite pictures East Street Racing 1-2-3!

Jim, remember you called yourself out ^. I never viewed this ^ illegal decal on screen.

 

My un-named comment that you responded to was when you had white duct tape with the words East Street in green felt tip taped to the top of your windshield frame to the roof. When we talked about the tape you called it a decal. As usual some people don't follow the written rule. Again as I stated to you the day we talked about this ^ issue, please read SCCA rule C. Authorized Modifications, been the same rule for many years. "Permitted components or modifications MUST NOT perform a prohibited function". Yes, one may use decals on a SM but when protested for areo infraction in either case, you loose. 

 

No I wouldn't protest anyone for the illegal actions you took with reference to decals, but it should make a point for others.

 

Have at it followers, flame suite on. 

 

 

[Jim Drago]

And thus the broken record ward as you have brought this up at least twice before

[Bench Racer]

And thus the broken record award as you have brought this up at least twice before

I fixed it for you ^.

 

To which, I challenge you to find the other two times I posted up this decal stuff related directly to YOU. I do respect your skills in the car, some of the other stuff, not so much.

 

Remember the pile of BS award that some may deserve.

[MPR22]

Let's do the license plate first. Among states it would be a parity issue. Some states require front plate, some do not require plate. The front plate holder is generally dealer installed.

 

Brick or not, I'd suggest the grill blocked below the hood is because more air to radiator is not required and it helps areo. Same for each side on the second opening down and same for the center of the third opening down and the same each side on the bottom opening.

If i needed less air to the radiator I would just put in a smaller radiator.  Designers use the grill as a major component of the personality of a car.  Look at the current line of Lexus, they all have essentially the same grill.  BMW ditto, Mazda Ditto.  

 

Argue all you want that a production car blocks off frontal area to reduce drag, it is quite irrelevant to the topic being discussed.  Those are production cars that have grills made be aesthetic pleasing first and fuel efficient second.  

 

Sprint cup cars are also irrelevant to this discussion.  The Sprint Cup cars are designed to run hot with little to no air flow through the radiator opening in a draft for 500 miles at high speeds. 

 

We are trying to utilize low cost methods of improving the performance of the cars that are available to all participants in all models years.  If the 1.6's are going to argue against taping because they have heat soak issues that would be a much more relevant argument.  

[Bench Racer]

If the 1.6's are going to argue against taping because they have heat soak issues that would be a much more relevant argument.  

 

Have you EVER heard me as a 1.6 owner say/post anything about my 1.6 having heat soak issues, no I didn't think so. I have questioned and attempted to support other 1.6er's with heat soak issues. Hey, I'm just a cheap a$$ed 1.6er who is very capable of figuring out how much radiator blocking is required to the front or rear of the radiator.

 

How come if all this tape has zip zero nothing to do with areo, I'm always reading about drafting, that would be areo, correct. How about when folks in the past removed their outside rearview mirrors, that was areo, correct, but naw taping over the bumper/grill/radiator is not areo,  
 

[Pete Maerz]

Pete this is pretty typical of screen tape to put heat in the car.

 

does this look like it would be a measurable benefit?

 

Without more information about your study about where the air was diverted, and other aero feature of the car, its hardly an apples to apples analysis.

 

I find it hard to accept that this is an advantage.

 

http://s300.photobuc...w=recent&page=1

 

Frank,

I hear where you're coming from. My intuition leads to the same conclusion. However, you should really spend the 25 bucks on the SAE paper. I downloaded it today and the results are intriguing. In addition to measuring drag and lift deltas, they also measured airflow at 24 locations on the radiator to be able to calculate the impact to heat dissipation. The test was run at 1/4, 1/2, 3/4, and fully blocked inlets. Far partial blocking, various techniques were employed that ranged from strips of tape (both vertical and horizontal) as well as blocking sections with cardboard. None of these configurations appear like they would significantly improve drag, but the results are empirical.

 

Some rough numbers from the study: 1/2 blocked inlet resulted in 3.5-4% overall vehicle drag improvement, a 2-7% reduction in lift coefficient (depending on the method) with a 25-30% reduction in radiator heat dissipation.

 

Of course, there's a disclaimer at the end: "The findings in this paper are specific to this vehicle and other vehicles may exhibit a
different outcome." Feel free to use that as your "out." I'm just saying that the research is eye-opening.

 

Lastly, don't get caught up in "closing the funnel" vs. flush taping the exterior of the bumper. Remember, it comes down to overall flow fields. When you close off the inlet, a stagnation zone builds in front of the car which causes the incoming air to flow over and around the car.

 

I believe you guys are proposing the change for noble reasons, but I contend that this rule allowance could be used for evil in the right hands (and it sounds like that is SCCA's belief as well).

[MPR22]

Have you EVER heard me as a 1.6 owner say/post anything about my 1.6 having heat soak issues, no I didn't think so. I have questioned and attempted to support other 1.6er's with heat soak issues. Hey, I'm just a cheap a$$ed 1.6er who is very capable of figuring out how much radiator blocking is required to the front or rear of the radiator.

 

How come if all this tape has zip zero nothing to do with areo, I'm always reading about drafting, that would be areo, correct. How about when folks in the past removed their outside rearview mirrors, that was areo, correct, but naw taping over the bumper/grill/radiator is not areo,  
 

1st of all I didn't say "you" referring to the heat soak.  I said that 1.6 owners (believe it or not you are not the only one although based on the volume of posts you are certainly the most vocal) have a relevant argument for not wanting others to be able to tape their grills if the heat soak issue comes into play.  

 

Drafting is the absolute extreme of aero, in fact the low pressure area behind the lead car not only reduces drag but literally sucks the trail car into the lead car.   Removing mirrors is non-compliant on many fronts, safety the most concerning. 

 

Nobody is going to tape the entire frontal area of the radiator opening unless they want to melt their cars.  

 

And even if it is an aero advantage so significant that it is measurable in trap speeds at Road America why does it matter if everyone is allowed the same advantage at no/low cost.  

 

 

 

Would you outlaw drafting in SM?

Would you outlaw bump drafting in SM?  Yes i know it is against the rule xx.xx, no contact...

 

If yes,  would that be for the betterment of the class or just because you feel it gives those that can an advantage that others might miss out on? 

[Craig Berry]

Pete, I am curious, and have zero idea myself, but I can see how tape might help move air around the car in NASCAR or any other race or street car where the grill is flush, but does your data take into consideration the goofy 10" deep hole in a Miata? I dont see how the air would still move around the car, but I am Not an engineer

[RazerX]

First Pete is correct and there is an advantage.  He, as rarely done on this forum, has provided VERY credible evidence that there is an aero advantage of some degree.  I have a degree in this area of engineering.  

 

How much is the question and completely dependent on other bits, such a chin spoiler, the speed you are at, proximity to other cars, etc..   

 

The question is, do we want taping and the complexity it can create.  For those veterans looking for the next little bit, the tape is it.  A little advantage, mixed with some experience and testing that could yield a small advantage.  However to a new competitor it might be just another set of complications.  He need a very good radiator(SD?), and the time, and the extra $$ to figure out how much tape yields which temp at which timing at what AFR, at what outside conditions. 

 

So some fun bit for the veterans or just another layer for a newby, to me that is the question.  Does this help the overall SM class or hurt it?

[RazerX]

Pete, I am curious, and have zero idea myself, but I can see how tape might help move air around the car in NASCAR or any other race or street car where the grill is flush, but does your data take into consideration the goofy 10" deep hole in a Miata? I dont see how the air would still move around the car, but I am Not an engineer

 

Yes, as Pete indicated it creates a stagnation zone, onto which, the on rushing air will be diverted (some over the hood, some to the side, some into the remaining opening and some under the car.  This is a very similar principal to why a pick up truck gets better gas mileage with the tailgate up.  Fluid flow is not intuitive for most.  Even thinking about the head gate, trying to visualize the flow with a plunge cut, edge coming from a 'charge' swirling over the edge of the value and adding 'vorticity' to the flow is very very difficult to calculate.  Hence the need for actual testing.  But that is another dead thread...

[Craig Berry]

Thank you for the explanations. Personally I dont care either way. I dont think moving from tape to no tape has or will change my finishing position. Whatever the rule is is what I will do. I do wish I would have known all this a few years ago, I would have been trying to run more tape!

[RazerX]

there are other aero tricks still available to our class, but it won't affect my finishing position either   so i don't go there.. 

[wheel]

The air intake for the radiator was a big topic for the CRB a few seasons ago, not just for SM, but for Production as well.  There is zero possibility of that rule changing.  The thread is interesting, even if nothing will come of it.  

wheel

[Cnj]

The air intake for the radiator was a big topic for the CRB a few seasons ago, not just for SM, but for Production as well.  There is zero possibility of that rule changing.  The thread is interesting, even if nothing will come of it.  
wheel

Well that's certainly a conversation stopper. Let's start arguing about aluminium lug nuts.

CNJ

[Bench Racer]

Thanks Wheel, I didn't want to go there because it would have been called BS on this site. IIRC, it came up on the prod site because there was no rule that specified one could have a screen. And then the tape tangent started. Similar as this thread except the prod was many more pages.

[FTodaro]

The air intake for the radiator was a big topic for the CRB a few seasons ago, not just for SM, but for Production as well.  There is zero possibility of that rule changing.  The thread is interesting, even if nothing will come of it.  

wheel

Wheel could you or someone explain why since many of us think this is a silly rule? It seams if the fear is going someplace you don't want it to go, that could be spelled out.