Topic: Streak went on scales

[snaponbob]

All I said is that I had heard/read this. Of course, I have heard/read where Cobalts have put 375whp down with a stock turbo and pump gas !!!!!!!!!!! What I would want to see is that intake air (at the throttle body) is lowered due to extra venting of the engine compartment. THAT matters. The cooling system can handle its task, and oil temps stay in line with whatever the factory designed. If there is a benefit - great. If not - that's great, too. As for panel replacement in Solo, NONE is allowed in any classes lower than SM or SSM is illegal. Exception would be OEM equivalent replacement due to non-availability such as the Sky front "fenders". I would be glad to detail that if one of the Mods would split this section from this thread.     

[wspohn]

Empty w/ CCWs &A6s bars connected RF perch adjusted
LF         1626#        RF
776          53.1%        800
1494#L   2963#T       1469#R
50.5%             49.5%
LR         1387#       RR
718          46.8%       669

Just for comparison, I corner weighted my coupe after sticking on the ZOK bars and the BC Racing struts and springs.
It was thus:

51.6% on front and 48.4% on rear with a 56 lb. weight bias to the driver side with a 200 lb. ballast in the  drivers seat.

Net weight with about 1/2 tank of fuel was 3025, about right for a coupe.  Knock off an insignificant 8 lbs. with the other wheels I have on it now.

These are definitely a bit on the porky side, with stereo and air conditioning and...and....

The magnesium top and rear window structure of the coupe doesn't add as much as you'd think, though.

[snaponbob]

Just for comparison, I corner weighted my coupe after sticking on the ZOK bars and the BC Racing struts and springs.
It was thus:

51.6% on front and 48.4% on rear with a 56 lb. weight bias to the driver side with a 200 lb. ballast in the  drivers seat.

Net weight with about 1/2 tank of fuel was 3025, about right for a coupe.  Knock off an insignificant 8 lbs. with the other wheels I have on it now.

These are definitely a bit on the porky side, with stereo and air conditioning and...and....

The magnesium top and rear window structure of the coupe doesn't add as much as you'd think, though.

If the lr/rf corner weight total worked out to 50% of the vehicle's total weight, you are spot on.

[Critterman]

If you add all 4 corner weights you get 2963 and divide by 2 you get 1481.5
If you add the lr-rf you get 1518 that's 51.23%

[snaponbob]

True Critter, but that is the empty weight. With 170 in the driver's seat, I am at 49.8 cross weight. I wrote down all this stuff, but it's out in the garage. All up, it was about 3135, but with ME in the car, it will be closed to 3150 with OEM wheels, so about 3140 with the CCWs and 315s.

[wspohn]

True Critter, but that is the empty weight. With 170 in the driver's seat, I am at 49.8 cross weight.

Ahem. I WISH my car was only 170 more with me in it.......

[Critterman]

170 that was only 40 years ago.

[JRinKY]

Regarding the discussion about  "wings" and downforce:

The factory spoiler is just that, it is not a wing. Steve misspoke when he referred to it as a wing. A spoiler does just what its name implies: it spoils the airflow at some point in its flow across the car. Every car generates lift, and it does it the same way an airplane wing does, by forcing the air that goes across the top of the body to move faster (relative to the body) than the air around the body. Higher velocity air, all else being equal, has less pressure than lower velocity air, and this is where the lift comes from. By spoiling the smooth flow of the air, the spoiler reduces the amount of lift generated.

A wing reduces the effect of the lift generated by the body by producing its own lift, in the opposite direction. Similar effect, but radically different method. A wing can actually generate more downforce than the body generates lift, while the spoiler can, at best, reduce lift to zero.

The major advantage of a spoiler over a wing for our application is the resulting effect on drag. A wing generates lift (aka downforce) by actively working on the airflow, and this will always create drag. A spoiler works on the airflow more passively, and will usually reduce drag, even as it is reducing lift. That is the case with the Kappa spoiler, and the effect at 100 MPH calculates to almost 5 hp.

Regarding the discussion about underhood temperatures:

Several of us did temperature testing a couple of years ago in response to a different discussion. We found that, with stock bodywork and the stock intake location, the intake air was within 1 degree of ambient by the time the car reached 30 MPH from a standing start. There is pretty much no way to improve on that. Obviously, drag racers would like to see lower temperatures while the vehicle is stationary, but no one else will see any benefit from changing underhood airflow.

Whether changing the airflow will cause problems is certainly an open question, but the greater question is: If making a change has no measurable effect, why do it ?

[BSRL]

Whether changing the airflow will cause problems is certainly an open question, but the greater question is: If making a change has no measurable effect, why do it ?

To be different and not to have fake vents.

[JRinKY]

 

BSRL  : To be different and not to have fake vents.

As long as your reasons are valid to you, and you recognize and accept the potential risks.

I don't know how much difference there is between a fake vent, and a real one that serves no purpose, but its not my car, and not my decision.

[snaponbob]

Ahem. I WISH my car was only 170 more with me in it.......

Ummmmmmm .. it was, ummm, my wife. I'm 190.

[kennysabarese]

Let's pull the aero stuff to it's own thread. This is getting interesting. Can a mod move the aero posts somewhere?

I have a question about spoilers. NASCAR just went back to using spoilers. But they look like they producer downforce.

Left - WING Right - Spoiler that looks like it would push down

[Graywolf]

Kenny They require you to wear arm restraints,6 pt harness, roll bar and helmet. Actually its strange your events require the top up.  If you roll over its more difficult to remove the driver quickly not to mention the fact that the top bracing might get entangled around your neck or arms.

[BSRL]

 
As long as your reasons are valid to you, and you recognize and accept the potential risks.

I don't know how much difference there is between a fake vent, and a real one that serves no purpose, but its not my car, and not my decision.

uh yea...there's a big difference, one is fake and non-functional and the other isn't.  It's purpose is to let hot air out of the engine bay.  Butter up your disapproval better than that.

[JRinKY]

BSRL : uh yea...there's a big difference, one is fake and non-functional and the other isn't.  It's purpose is to let hot air out of the engine bay.  Butter up your disapproval better than that.

Not disapproval, disagreement. You don't like having a fake, non-functional vent, and, actually, neither do I. The difference is that you converted yours to a real, functional vent that doesn't need to be there, and I chose to accept that, real or fake, functional or not, the vent serves no practical purpose. Two different approaches, same result, since we are both happy with what we have.

Kenny : I have a question about spoilers. NASCAR just went back to using spoilers. But they look like they producer downforce.

Left - WING Right - Spoiler that looks like it would push down

They are both spoilers. For a wing to function it has to be in clean air, and there has to be enough space under it for the airflow that generates the downforce. Even though the one on the left looks like a wing, it is much to close to the deck lid to be a working airfoil, so its function is that of a spoiler.
 

[kennysabarese]

so regardless of the steep angle the NASCAR spoilers are not generating downforce? Interesting.

[snaponbob]

They do.  That is why NASCAR so carefully measures their height and angle as well as require the braces in back of them. 

[BSRL]

Not disapproval, disagreement. You don't like having a fake, non-functional vent, and, actually, neither do I. The difference is that you converted yours to a real, functional vent that doesn't need to be there, and I chose to accept that, real or fake, functional or not, the vent serves no practical purpose. Two different approaches, same result, since we are both happy with what we have.

Dude, the practical purpose is to let hot air out of the engine bay.  The vents do that.  Your temperature tests had nothing to do with this fact.  Fact is with open vents to let out hot air, the engine bay will be cooler and/or cool off the engine bay area quicker than with no vents.  Are you going to deny this?

[wspohn]

Some interesting twits and turns on this thread.

I'll stay out of it, except to mention that where vents are concerned, you NEED to do a 'tuft' test to see if they are working the way you think they should.

I can cite many instances of venting in hoods or body where they are too close to the high pressure area at the base of the windshield and you find that at speed, tufts of yarn taped near the vents are drawn in, rather than blown out.

One classic is venting behind the radiator to allow egress of air that has gone through the radiator.  That only works if the venting is far further forward than people usually want it for styling reasons - like right behind the rad level.

All sorts of cars have fake vents - the rear 'brake' ducts behind the doors on old Mustangs are a classic, looking like they should do something but going nowhere.

[BSRL]

Hey, I'm not making any other claims other than an open vent will let hot air out better than no vents at all.  As for all these other issues, if someone is worried about them then so be it, don't open your vents.

[wspohn]

Hey, I'm not making any other claims other than an open vent will let hot air out better than no vents at all. 

And I am pointing out that your statement, based as much on instinct as reason, isn't necessarily true. It may in fact let air IN, rather than OUT.

I expect that what you said it is true as far as the front fender side vents are concerned given that they are not in a high pressure area (the added heat issue for the ECM is something I have neither the knowledge nor inclination to address).

But your original statement was:

As long as it's not the same guy who said not to open any of the vents (hood or side). 

(My emphasis)

and I was just pointing out that having vents, as opposed to no vents (your statement) isn't always better when it comes to the hood. Unless hood vents are far enough forward, they won't do what you thought they would.  Has anyone opened up the hood vents on the Sky to see what happens to flow? 

Of course you need to balance cooling against allowing ingress of rain water when you do that, another consideration to weigh.

[JRinKY]

BSRL : Dude, the practical purpose is to let hot air out of the engine bay.  The vents do that.  Your temperature tests had nothing to do with this fact.  Fact is with open vents to let out hot air, the engine bay will be cooler and/or cool off the engine bay area quicker than with no vents.  Are you going to deny this?

You are making what I consider to be two faulty assumptions.

Bill has addressed one, that vents you think are helping may be doing nothing or may in fact be hurting. Airflow around a vehicle body is far from intuitive, and, as he stated, frequently works out quite the opposite of the way you think it should. You may be cooling the engine bay faster, or you may be affecting the designed airflow patterns to the point that you are inhibiting the cooling of things that need to be cooled. Unless you have done extensive testing you really have no idea what is happening. A key thing to think about here is that the people who designed your car were interested in fuel economy, performance, and longevity. Even given the expense of already having a fake vent designed into the body they chose to not use them. They used computational fluid dynamics, wind tunnel testing, environmental chamber testing and extensive real world testing in a variety of extreme conditions and still decided that no vents were needed. I will not try to claim that any engineering group is infallible, but in competition with raw intuition, my money is on them.

The second faulty assumption is that removing heat from the engine bay is necessarily a good thing. There is quite a lot of research that shows that operating an engine at higher ambient temperatures makes it produce more power, more efficiently. Certainly reducing intake temperature will improve the engine's performance, which is why we did the tests that we did to check temperatures at the intake. Unless you are experiencing overheating, or other heat-induced component failures, reducing engine bay temperatures is of very questionable value.

Dude.

[normsf]

OK why are we beating this dead horse. Any time you add extra horsepower whether by a larger turbo, headers or whatever you increase Heat, you need to get that extra heat out or you will decrease the life of your engine components at least back to normal stock baseline. Thats where the vents come into play, yes they work, period. Every customer that has installed our hoods and fenders for example has seen a decrease in temp to at the least back to stock baseline. You can discuss what the factory did or not its all based on costs, even a dollar added that is needed to make the vents functional is a dollar lost to the manufacturer all they want is to make it work good enough in everyday work life. GM was not interested in having a enthusiaist getting the most out of an engine theyby increasing the performance and heat to make the vents potentialy functional. Horsepower adds heat, driving hard adds heat you have to get rid of that heat or it dies, very simple. Thanks Norm

[JRinKY]

Adding power certainly adds to the heat load seen by the engine's cooling system, but only increases the engine temperature when that heat load exceeds the capacity of the cooling system. Anyone who is not experiencing elevated engine temperatures is unlikely to benefit from additional cooling.

Cost to a manufacturer extends beyond build cost. CAFE is a major deal to manufacturers, so if a vehicle can be made more efficient at relatively little cost it probably will be. GM warrants the drivetrain for 100,000 miles, and the costs associated with that warranty can be extremely high. If a vehicle can be made more reliable for relatively little cost it probably will be. The costs associated with the installation of vents had already been incurred with the fake ones. Changing them to be functional would have added little, if any additional cost, so if added venting was beneficial there was little standing in its way.