Jump to content
HybridZ
Mikelly

Windtunnel Testing the Datsun S-30 Z

Recommended Posts

No.There is a high pressure region at the base of the windshield.The original purpose of the original "cowl induction"hoods was to tap into this high pressure to help feed the engine's induction system with cool positively pressurized air.Of course nothing is certain until tested.The windshield base/cowl area of the Z has very complex flows and pressures.You have high and low pressures adjacent to each other.Very small details in this type of zone can swing downforce and drag numbers from one and of the spectrum to the other.There really is not enough data to draw any conclusion yet.Let's go back to the tunnel!

Share this post


Link to post
Share on other sites

okay...i was looking at the numbers on the jpeg image and i couldnt really make much of it (havent got into aerodynamics yet ;) ). is there any way to kind of sum up what works vs what doesn't? i.e.: headlight covers = less drag, etc??? if not its okay...maybe if i stare at it long enough it will "magic eye" into something useful lol

Share this post


Link to post
Share on other sites

Was wondering what happened to this thread? Sounds like intresting stuff, but is there suppose to be some pics?

 

Also as far as negitive underhood pressures go. Dont forget to duct in some good air for your motor or you could cause flow problems for the motor when it needs it most. I have seen motors get choked out with ducts in the wrong places.

 

 

EDIT""" Sorry I found it.

Share this post


Link to post
Share on other sites

You might be interested in knowing that we found that "less air" is more when it comes to ducting to the radiator. According to the windtunnel engineer, NASCAR uses 2X4 inch openings for air flow to the radiator and close or open them with tape as needed...

 

Do a bunch of reading on this test. We found a lot of great info.

 

Mike

Share this post


Link to post
Share on other sites
You might be interested in knowing that we found that "less air" is more when it comes to ducting to the radiator. According to the windtunnel engineer, NASCAR uses 2X4 inch openings for air flow to the radiator and close or open them with tape as needed...

 

Do a bunch of reading on this test. We found a lot of great info.

 

Mike

 

 

Was that directed toward me? I think i already put that same info in another thread about tilting the radiator. I think you missunderstoodwhat I was saying as i was talking about choking the flow to the motor not through the rad. I totaly agree with what you said above though.

Share this post


Link to post
Share on other sites

I just thought I would share my 1976 280z 2+2 Wind Tunnel Testing I completed recently, I figured it would be great food for thought for our resident aerodynamics specialist to comment on, as well as everyone to benefit from.

 

Best of all this testing was done for free overnight while I slept and yielded the optimum aerodynamic profile for a S30.

 

Here you go:

spict0001_thumb.jpg

spict0002_thumb.jpg

spict0003_thumb.jpg

spict0004_thumb.jpg

16068_thumb.attach

spict0006_thumb.jpg

spict0013_thumb.jpg

spict0014_thumb.jpg

spict0015_thumb.jpg

spict0007_thumb.jpg

Share this post


Link to post
Share on other sites

I added a dead on rear view I found this morning.

 

Yea, I live on top of a hill in the escalante valley which is the esophegous for the tri state area, this valley runs 300+ miles north to south and balences the northwest and southwest jet stream weather fronts. We get hilatious winds anytime there is a High/Low pressure differential from one end of these states to another. See http://www.milfordwind.com/milford/

 

These pics were taken about 2 winters ago, wind out of the north head on to the front of my Z at the top of the hill, with fine fluffy snow that filled in all the eddys. I quickly got my camera out after discovering this in the morning out on my puppy walk :mrgreen:.

Share this post


Link to post
Share on other sites
I just thought I would share my 1976 280z 2+2 Wind Tunnel Testing I completed recently, I figured it would be great food for thought for our resident aerodynamics specialist to comment on, as well as everyone to benefit from.

 

Best of all this testing was done for free overnight while I slept and yielded the optimum aerodynamic profile for a S30.

 

I find the affect of the drip rails the most interesting.

 

Cameron

Share this post


Link to post
Share on other sites
I just thought I would share my 1976 280z 2+2 Wind Tunnel Testing I completed recently, I figured it would be great food for thought for our resident aerodynamics specialist to comment on, as well as everyone to benefit from.

 

Best of all this testing was done for free overnight while I slept and yielded the optimum aerodynamic profile for a S30.

 

Here you go:

 

i wonder if stretching the windshield out about 6-9 inches on the bottom will cure the air building up on the bottom of the windshield problem.

Share this post


Link to post
Share on other sites
i wonder if stretching the windshield out about 6-9 inches on the bottom will cure the air building up on the bottom of the windshield problem.

I think it would lower drag. I also think that if lowering drag is your main goal, you should start with a different car. We know the base of the windshield is a high pressure area. How much would downforce be affected by lessening the angle of the windshield is probably similar to asking how much downforce would be affected by lessening the angle of attack of a spoiler.

 

The Primadonna Z's have the center of the base of the windshield moved out quite a ways, so it wouldn't be the first time it was done though...

Share this post


Link to post
Share on other sites
I think it would lower drag. I also think that if lowering drag is your main goal, you should start with a different car. We know the base of the windshield is a high pressure area. How much would downforce be affected by lessening the angle of the windshield is probably similar to asking how much downforce would be affected by lessening the angle of attack of a spoiler.

 

The Primadonna Z's have the center of the base of the windshield moved out quite a ways, so it wouldn't be the first time it was done though...

 

I was thinking along the principle's of splitting the air along the sides as much as possible and using downforce creating devices to make a majority of the downforce.

Share this post


Link to post
Share on other sites

This thread deserves some more love after being asleep for a few months.

 

I saw some mention of this but never any insight. Test 4 to 5, popping the hood dropped the front lift 100 pounds? Anyone have any insight as to why this is? I know the general idea agreed on is that the windshield is a high pressure area, and popping the hood vents some of that pressure into the engine bay (bad). But is it possible the sides of the hood are releasing enough air pressure to counter-act this and reduce the over all force under the hood of the car?

Share this post


Link to post
Share on other sites

This thread deserves some more love after being asleep for a few months.

 

I saw some mention of this but never any insight. Test 4 to 5, popping the hood dropped the front lift 100 pounds? Anyone have any insight as to why this is? I know the general idea agreed on is that the windshield is a high pressure area, and popping the hood vents some of that pressure into the engine bay (bad). But is it possible the sides of the hood are releasing enough air pressure to counter-act this and reduce the over all force under the hood of the car?

Seems that there is less positive pressure at the base of the windshield than what can be vented along the sides and possibly the back of the hood. If the lift is reduced, the underhood pressure is going somewhere. I think you'd have to do some yarn tests to figure out where air goes in or out. I know we've talked about one guy who did such a test with a cowl induction hood and he found that the yarn went alternately in AND out of the cowl. Even if it is venting out the back of the hood part of the time, it certainly doesn't seem like the best place to do it.

 

I'm convinced that the better way to deal with air under the hood is to prevent it from getting there in the first place. I'd like to see a yarn test on a popped hood or a cowl induction hood from someone with a radiator duct and the rest of the grill blocked off. I would put money down that the air goes solidly into the cowl under those conditions. I'd up the money on such a bet if there were hood vents installed. A good hood vent would allow the high pressure under the hood an escape and would actually help to suck it out with low pressure on top, making the pressure differential at the cowl greater still.

Share this post


Link to post
Share on other sites

Have to concur with you entirely on that notion. If no one does this within a month or two, im going to do it myself and post some videos.

 

Anyone know for sure if the fenderwells are low pressure areas or not? OR have a pracitcal way to allow them to be? Ive seen mention of it and keep playing with the idea of opening the engine bay to the fenderwells via vents. I really need to get myself one of those gauges that let you measure air pressure haha.

Share this post


Link to post
Share on other sites

×