Chad,
Which vents are you looking at...track spec?

Here's a shot. It's an AMD aluminum hood, so it still has an under structure that we had to modify a bit.

http://i366.photobucket.com/albums/o...A/DSC_0755.jpg

Just curious, what are your oil temps? Maybe a thermostat that opens sooner, or more oil capacity could help the issue.

Sounds like a great couple of weekends with your car Chad, congrats on that. Love seeing you and others out there beating on their cars.

I've seen your friends motorhome in the background of several pics from events out there and lust over it every time. We are still looking at getting something very similar to that at some point. It's nice having a retreat like that in the paddock on a hot day, isn't it?

They are currently number 1 on my list, yes. I'm still debating adding them to my current painted steel hood or getting an aftermarket carbon fiber / fiberglass hood. The thing is, that with the aftermarket hoods that are under $1k they all have the same under structure so I don't really gain anything (airflow wise) going aftermarket unless the under structure is modified. Perhaps easier to do with fiberglass.


Now that I've have been studying hoods closely I have to say that thing looks awesome! How did you block out the rear cowl induction area of the hood? I'm noticing that even if I block the normal opening for cowl induction in the hood that the hood under structure still leaves a large gap in that spot for air to be pushed into the engine compartment.

I have an improved racing adapter with built in thermostat. It begins opening at 180* and fully opens by 200*. Unlike what I have read and heard about other oil thermostats this thing works really well. No matter how cold out it is I haven't seen oil temps below 195 once everything is warm and heat soaked.

I consistently see over 250* oil temps on a 20 minute road course session. My current oil temp gauge only goes to 250* so I need a new gauge to see just how high it is getting. This motor heats the oil pretty badly compared to others which is why I chased oil pressure issues until adding an oil cooler.

I'm running a 10" x 13" oil cooler which is the biggest I could fit without modifying the core support to ditching a/c. This added about another quart to the system so total capacity is about 6.5-7 quarts.

Thanks Lance! The motor home was pretty amazing! The A/C really made a difference given how hot it was and that the pits normally don't even have shade available. Also, he has a full fridge, freezer, and TV. It rocks.

first gen camaro aero testing post!
 

So as I indicated with my teaser pic the other day I have gotten more interested in hood vents for the cooling and potential handling benefits. I searched extensively on here and pt.com for info and found a lot of people talking about "how" to do the testing but nobody actually sharing their results. I also searched a lot online and found some cool writeups by autospeed.com on tuft testing and pressure testing with a magnehilic gauge.

Tuft testing.
http://www.autospeed.com/cms/article...art-1&A=108656

Pressure testing.
http://www.autospeed.com/cms/article.html?&A=111111

So I tackled this myself and am sharing the results with you guys. This is my attempt at comprehensive hood vent testing on a first gen Camaro cowl hood. Doubt my findings would change between a 68 and 69.

First. I did the wool tuft testing shown in this pic. The taped outlines correspond to the holes in the under-structure of the cowl hood.
https://igcdn-photos-g-a.akamaihd.ne...57370981_n.jpg


Here is the video with speeds up to 70 mph.


Based on the wool tuft testing the pressure wave in the cowl area was not as big as I thought it would be. You can see the last row of tufts on the hood itself are starting to deflect. I also taped two extra tufts on the very edge of the cowl portion of the hood and predictably they plus any of the tufts taped to the cowl panel itself are being sucked right into the cowl opening on the hood which is exactly opposite of what you want to happen for cooling or handling performance on a road course.

You can also see that the raise hump on the cowl hood has the smoothest laminar airflow. Based on this test alone it was clear to me that the best location for a hood vent is the cowl hump immediately after the radiator. The problem is that an OEM styled cowl hood doesn't have much of an opening in this area in the under-structure of the hood. The taped outline of the opening in that area is about half in front of the radiator fan opening and half behind. So you can only use half that space which is a tiny area.

I was feeling inspired after reading the autospeed article on using a magnehelic gauge so I ordered one that measured between 0 and 1.0 inch of water.
http://us1.webpublications.com.au/st...11111_16lo.jpg

In hindsight I should of gotten a gauge that went to 2" or more of water. I pegged the gauge in some of my tests. There are areas of the hood with what appears to be significantly greater than 1" of water pressure differential between under the hood and above the hood on a first gen Camaro cowl hood.

I did two types of tests. Test 1) the pressure difference between the top of the hood and the interior of the car with the windows cracked an 1" on either side. Test 2) The pressure difference between the top of the hood and directly opposite underneath the hood.

Here are the readings from test 1 (hood is lower pressure compared to cabin except for position 3).

Position 1.
Reading at 50mph - fluctuated .3 to .4 inches of water
Reading at 70mph - fluctuated .8 to 1+ inches of water. Average of 1.0" I haven't even started measuring underhood pressure differential and am already maxing the 1" gauge.
http://i1380.photobucket.com/albums/...psxaqw5h5y.jpg

The little piece of tape sticking in from the left below the black tubing is where my radiator fan shroud ends.

Position 2.
Reading at 50mph - fluctuated .2 to .4 inches of water. Average 0.3"
Reading at 70mph - fluctuated .4 to .8 inches of water. Average 0.6"
http://i1380.photobucket.com/albums/...psymbgeryu.jpg

Position 3 (pressures differential reversed and is now higher on hood than cabin).
Reading at 50mph - held fairly steady at .1" I wasn't that interested in this location so I didn't measure at 70mph.
http://i1380.photobucket.com/albums/...pskbzdznm2.jpg

Test 2 with tubing to both sides of the hood.

This is what it looks like in Position 2 (note the openings I've done a tape outline of on the top of the hood).
http://i1380.photobucket.com/albums/...ps1ggaiw1z.jpg

And the Test 2 measurements.

Position 1.
Reading at 50mph - fluctuated .6 to 1.0 inches of water. Average of 1.0"
Reading at 70mph - Pegged the guage. Didn't even wiggle. Because the gauge was pegged I compared to the underhood pressure to the cabin. The hood was fluctuating between 0.4 - 0.8 stayed mostly between 0.6 and 0.7. Adding the above hood pressure in test 1 to this test would be a differential of 1.6-1.7".

Position 2.
Reading at 50mph - fluctuated .4 to .6 with momentary spikes to .8 inches of water. Average of .5+"
Reading at 70mph - fluctuated .9 to 1+ inches of water. Average of 1.0"

The Magnehelic confirmed the instincts I had from the tuft testing. The center of the hood immediately behind the radiator fan shroud (Position 1) is the best place for a vent and significantly better than vents to the side of the cowl hump farther back. BUT this location benefits best from either cutting the understructure of the hood or a high dollar hood with no understructure. However, the side location (Position 2) would still provide excellent venting with 0.5" pressure differential at 50mph which is significant and requires no cutting of the understructure!

For random comparison I took the pressure readings from the front of the A/C condenser and back of the radiator with the car off and fan on (12v instead of 14v) and the radiator fan was pulling 0.36" of water.

Conclusion TL;DR
Position 1 is best but benefits from modified or no understructure.
Position 2 is a great alternative and doesn't require modifying the understructure.
Regardless of which position block off the cowl hood opening and get a super thick cowl to hood seal!

One other random thought or info.

1.0" of water is = to 0.0360911906567 PSI.

A camaro hood is roughly 4' x 4'

Remove 6" for cowl pressure and you have about 2016 square inches.

An average of 0.75 inches of water pressure differential over that surface.

You are looking at about 55 lbs of lift on just the hood. No wonder my hood latch failed with two track days with speeds of 150+ and 130+

If you are able to route a lot more air out the top of the hood rather than under the car then I'm guessing that can result in a downforce change of a lot more than 55 lbs. But that probably requires a lot larger hood vent opening a la one lap camaro.
http://www.themusclecarplace.com/wp-...ipkaCamaro.jpg

:thumbsup:

http://imageshack.us/a/img825/7677/h...camarologo.jpg

good to see some pictures of the testing. and the reason i want a flat hood now that the carb is gone. cowl hood is really only good for a carb setup or if you need room in the bay. some like the looks also. looks like what chevy found when the did the areo for the 2014 camaros with the hood vent .
http://mixmotor.eu/wp-content/upload...Camaro-016.jpg

Remember, the purpose of the cowl hood was to pull fresh air in for the carb.

I would be curious about the pressure difference if you vented the side of the fender instead of the top of the hood...like a second gen Trans Am. Seems to me you would be pulling the air that is packing up against the fire wall.

Great work, by the way, thanks for taking the time!

Hey Carl, does your hood have any understructure in the area of the vent like a factory cowl?

I like the styling of the cowl hood but the flat is probably easier to build large venting in ala OLAC.

Yup.

Yeah I did some staring at the the side fenders and may do a pressure differential test in that spot for fun though for style purposes I'm not sure I would add any venting. I'm also thinking about doing some tuft or pressure testing around the inner fender openings. My TCI subframe kit came with block off plates to seal the opening from the inner fender to subframe which I never installed. I'm wondering if that section allows high pressure air from the wheel well to enter the engine compartment too.

No structure in that area. It a fiberglass part made by JCG.

I too toyed with the idea of fender vents. On a new build perhaps it would be worth it. On some of the Chrysler hemi cars there were top fender vents installed. When tested recently for functionality via the oil drop method, there was zero movement in the drop even at 100+ mph.

Time for an update including an important fundamental understanding of how the factory thermostat works in LS motors.

So I've been chasing an electrolysis issue which wiped out my AFCO radiator. It was still functional but had a pinhole leak that would show up after a track day or other high heat event.

Since I haven't fully cured my electrolysis but wanted a new radiator before this weekend's Optima event I bought the cheapest one I could find. The Griffin 8-00009-LS from Summit.

A couple of notes about the radiator.

• Has the 23" core but very narrow tanks so the driver's side mounts in the SBC location
• core isn't as centered in the core support openeing as the AFCO was
• Claims to use the correct sized inlets & outlets but the lower hose uses a 1.5" outlet where the AFCO used 1.25" I think factory on a lot of LS cars is actually 1.25"
• Core is about .5" taller than my old AFCO

The narrower side tanks also caused the outlets to move slightly and required new hoses. After several trips to the auto parts stores I finally found hoses I could cut and make fit without resorting to the universal hoses. I used the following:
Lower - Gates 21585
Upper - Dayco 71576 (length code D)

I also took this opportunity to install the 75-79 Chevy Nova coolant recovery tank in the passenger fender. Learned about this from Vince on this site. The older I get the more I appreciate function over form. I was tired of my billet tank which I could never accurately tell how full it was and it was catch can style rather than recovery. I wanted something I could see the level at a glance. Here is the pic Vince shared. I haven't taken one of my own set up yet but it looks pretty much the same.
https://lateral-g.net/forums/atta...1&d=1420520597

So once I got everything mounted I thought I was chasing an air bubble due to low coolant flow at idle. This had happened to me before where at low engine speed the car would run warmer. This is regardless of vehicle speed or the fan being on/off. Rev up the engine and it would cool right down.

Well after lots of research online I stumbled on a bunch of threads at LS1tech.com talking about the need to have coolant flow through the heater hoses because that is how the thermostat senses when to open. Because the LS thermostat is on the lower radiator hose but has the sensing component on the back side of the thermostat it won't open based on the temp of the coolant coming from the radiator. The Factory Thermostat has a "bypass valve" on the back side of it that will allow hot engine coolant to hit the backside of the thermostat when it opens but the reading I've done online says this only opens with 5+ PSI of pressure. This would explain why at idle my car hits 210* and stays there but as soon as I blip the throttle it would drop below 200* fairly quickly. That blip of the throttle is likely opening the bypass valve which allows hot coolant to wash across the back of the thermostat and triggers the thermostat to open more fully.

The bypass valve on the back of the t-stat looks like this:
http://bertok.us/pics/l31marine/3/tstat.jpg

To test this I got the car nice and hot and then switched my heater valve open and within in a few minutes I could notice a huge difference in the behavior of the thermostat. Watching the coolant flow from the upper radiator hose I could see the Thermostat opening at a lower ECT and opening much farther (saw a lot more flow). I could actually see the temps cycle consistently.

Here is a video of the the behavior of temps with the valve open and then the valve closed all at idle with a fully warmed up engine (oil temps over 200* too).



Final note. This issue runs 50/50 on LS1tech.com between those who claim you can't block the heater ports and those who have blocked off the heater ports and notice no problems. But if you are ever fighting low engine speed/idle temps this might be one to check out.

Chad, you doing Fontana?

Hey Mike. Yes I will be there tomorrow morning! Are you?

Whew what a weekend at the Fontana Auto Club Speedway with the Optima USCA. Man was that ever a hot weekend and car event!!!!!! I drank over 350 liquid ounces of water and Gatorade Sat & Sun and I still lost 7 lbs in those two days and had dehydration related cramping.

However, it was still a fun weekend. No other event that I've been to besides Optima USCA do you see such a wide variety of cars and while it gets increasingly competitive every year its great seeing the camaraderie continue and getting to see some of my fellow competitors and friends.

This was the last Optima USCA event before the invitational at SEMA and the competition in the GTV class was off the hook compared to my previous experience in April in Vegas. I was very happy that in all three driving events I managed my best times in my last runs. Regardless of how I stack up on the scoreboard I always feel much better when I see consistent improvement throughout the day at a driving event. Overall I came in 9th out of 33 GTV competitors which considering the competition is something I pretty happy with.

Getting after it on the autocross (thanks Tim for the pic)!
https://lateral-g.net/wp-content/uplo...teries-500.jpg

And video of my best lap on the road course. I did 5 sessions and it took me many tries to get to this time lol.


Edited to add: I feel like I'm finally starting to get the car and most importantly the driver sorted on the road course. I still have a lot left to learn but this past weekend I probably did more throttle induced oversteer than the rest of my track driving combined and it felt good to predict it, control it, and even prevent it.

Also, great job to Jimi Day and the whole Optima USCA team for another really well run event. I was especially appreciative of the ability to wear shorts on Saturday for the autocross and speed stop and the extension of judging to Sunday.

Also, thanks to TCI Engineering and Wilwood for great hospitality over the weekend.

Electrolysis can be caused by a blown head gasket. I chased electrolysis on a car for months and it dissolved 5 heater cores. GM had me doing all kinds of stuff from flushing the cooling system with baking soda to soldering grounds onto the heater core and radiator and adding new grounds to the block. What it came down to was a blown head gasket that would let exhaust gas into the system but wasn't bad enough to burn coolant.

Chads 68
 

I saw your results the other day... very good in the company
you are running.. and some have brand new tires etc

thanks for the update... glad you did well

Bob

Congratulations on the 9th finishing place.

I hope it isn't that and don't think it is based on the testing I've already done. Will keep it in mind though.

Thanks Bob. I was one of them running new tires :D but am still happy to get into that company!

Thanks David!

Fun pic from one of my videos this past weekend. I was employing the Cars movie strategy. Tun left to go right!

http://i1380.photobucket.com/albums/...pszhik67mb.png

Had another great weekend!

Ran the autocross Saturday at the NMCA West Hotchkis autocross event. These are always fun events because they bring out a great group of folks with a very diverse set of cars. The course is built and hosted by the Byrds and for the final Hotchkis autocross of the season they really stepped it up. The course had more variety than past events as well as being much longer. Average run times were in the low 50's compared to low 30's of other events. So more than 50% longer in lap time and that is with a straightaway that I was hitting up to 80 mph on! For Saturday they went the extra mile to ensure everyone got 9 runs on this fantastic course too. The last run group finished at the beginning of dusk and our awards ceremony was pretty much in the dark so props to the event host for keeping it going literally all day long.

Of course I was stoked to win the classic muscle class! Evan from TCI was swapping first place with me all day in his 63 Nova. After the beating I received at his hands in Del Mar this year I was anxious to return the favor :)

https://scontent.cdninstagram.com/hp...39722597_n.jpg

http://i1380.photobucket.com/albums/...psy1t4uiww.jpg

And my biggest rival for the day
http://i1380.photobucket.com/albums/...psln1ds3uy.jpg

Evan on his last run looped it and kept the loud pedal full depressed...
http://i1380.photobucket.com/albums/...pskq1wzxqw.jpg

Finally, here is video of my best lap of the day.

So, check out what I stumbled across this morning...

http://www.apexjunky.com/featured/ga...q1B0w.facebook

Congrats on the great write up Chad!

Thanks Lance! I just realized I've been neglecting this thread. Lots of events attended and at least one mod since my last update. Will have to get busy!

1 mod?... Where's the update?

Hopefully it was the driver mod. :peepwall:

A minor one. I changed the wheel centers from polished aluminum to gold using Plasti dip. Results weren't amazing but it is easy to remove it and go back to polished centers. I'll post up more about it when I get some free time.

ha ha ha. The driver may have seen some modification but needs a whole lot MORE!!

Don't we all. :sieg:

I thought I noticed those gold centers -- looks great man.

i saw an Instagram pic with gold centers... Looked good

Thanks guys. I really like the gold center look and if I had ordered my wheels about 6 months after I did that is what they would of been. I also, liked the plasti dip look when fresh but it isn't as shiny or bright of a gold color as I wanted however, the biggest issue is that when you use the glossifier or metalizer top coats like I did it attracts brake dust like nobody's business. I've had to scrub so hard in trying to get the brake dust off that I have started to remove some of the gold coating already.

Will due a full post on how I did it and the results when I get some extra time.

So I haven't been updating this thread as much but I've still been doing a ton of events and continuing to tweak little things on the car. Mostly maintenance related.

As I mentioned I've now painted the wheel centers gold. I used Plastidip vintage gold with gold metalizer which is temporary and supposed to be easily removed as long as you apply it thick enough.

The one issue is that gold metalizer uses the Plasti dip glossifier with gold metal flakes and glossifier leaves a more noticeably rubbery finish rather than smooth. This stuff is a magnet for brake dust. Like crazy bad. It comes off but requires some elbow grease and I've read that if you leave it on it will stain the dip.

First pic shows the before, after painting, and after a track day at Laguna Seca.

http://i1380.photobucket.com/albums/...psuuvfptvn.jpg

Here is a shot of them on the car with about 500 miles of driving on them.
http://i1380.photobucket.com/albums/...psfrxrgfhz.jpg

And for posterity sake here is the Laguna Report I posted in Greg's thread.

I planned to be in the bay area for Thanksgiving already when I originally saw this post by Greg back in September. A quick look up on google maps showed that Laguna Seca was just over 80 miles from my Grandma's house so it became game on! I signed up comforted that I could cancel my attendance right up to the 20th and still get a full refund as I was worried about getting rained out. I will put my car though a lot of different abuse and risk but having been on track during the rain its above my own comfort level.

Using my Grandma's house as a base of operations I put 1,039 miles on the Camaro between Wednesday night and Sunday while knocking down about 18mpg. Wednesday night was a midnight run up the state, while Sunday was lots of stop and go driving. Through all of this and getting flogged pretty hard on the track the only tool I pulled out on the trip was a tire pressure gauge. Winning!

Some of my favorite pics from the event.
http://i1380.photobucket.com/albums/...ps1vi0ugs5.jpg

http://i1380.photobucket.com/albums/...psdemsqfbn.jpg

http://i1380.photobucket.com/albums/...psmtfzc7ri.jpg

http://i1380.photobucket.com/albums/...pswdhx1lco.jpg

Lots of good pictures of the variety of cars on the Shelby Club's facebook page here too: https://www.facebook.com/NorCalSAAC/...12315592203978 including an original GT350 used at the Shelby School back in the day.

This is the second Shelby Club event I've attended and its the only track day events I've been to outside of the RTTC and Optima events that draw a large attendance of classic muscle. Lots and lots of mustangs (old and new), cobras and even a Daytona coupe!

It was a super cold day (morning temps in the low 30's) and I was inititally really worried about tire temps but after my first session I got comfortable with the level of grip available. I think street tires like the Falkens were a little less susceptible to the super cold temps than all the race oriented slicks I saw in the paddock.

The Shelby club has a strict no lap time policy so I didn't push myself as hard as I might have if I knew every lap time but I still pushed pretty good and had a lot of fun. After coming home and reviewing the data and video I saw a number of places I left a lot of time on the table. As it was, without a roll bar I was limited to the intermediate group and was quite a bit faster than most of the folks in my run group.

Here is video of my shortest session (the longer ones are giving me editing trouble). Lots of passing, especially the second half of the video.



It was great meeting up with everyone from the forums and bench racing and getting some driving tips. Best "Black Friday" I've ever had!

Aaaand for the second time this year I did track days two weekends in a row (back to back), though this time the first one involved a 1,000+ mile round trip and the 2nd one was 400+ miles round trip! I'm racking up the miles on this car!

This past Sunday I hit Buttonwillow. This is the first time I've been on this track since 2011 and personally is the track I've been MOST looking forward to running V3.0 of my car. Buttonwillow is one of the more varied tracks in SoCal IMO and offers a fantastic comparison of my new and old setups.

Sadly, I only got a couple of traffic free laps but I managed to run a best lap time of 2:05 which was about 9 seconds faster than my old best. In reviewing the video of my best lap there is at least a few seconds available just cleaning up my driving so I think I might be able to run a 2:02 or 2:03 on my 200TW Falken street tires!

Here is the video of my best lap. I had gopro malfunctions so this is just my iphone's camera set to 480 resolution.


I did manage to capture a cool shot of my first ever off track excursion on Truck Stop.
http://i1380.photobucket.com/albums/...pswf3w0ky0.jpg

This track day was also impacted by two negative experiences. One huge one. There was a serious wreck coming out of the esses towards sunrise corner which resulted in one fatality and one person with major injuries being air lifted. It was a very sobering reminder of how dangerous track days can be. Especially since the car involved was was fully caged, fixed back seats, 5 point harnesses, and was being driven by a "professional" driver who has operated a tuner and builder shop since 1995. Due to the violent passenger side impact against a concrete wall (corner worker station), speculation is that due to lack of a containment seat the driver suffered a lethal sideways injury to his neck/head while the passenger who was in the impact zone had a passenger airbag / door to stop the helmet movement.

The second negative which is totally minor in light of the accident was that I lost my dash, marker, and tail lights and despite playing with a multimeter and fuses for a few hours I wasn't able to figure out until I got home that the Horn fuse was the culprit. Painless wiring runs the power for the driving lights (not headlights) through the horn fuse!!

You don't ever want to hear about a death on a race track ... safety is paramount is these street cars! My heart goes out to their families!!!

The Buttonwillow death (let's call it what it was rather than downplaying it to an "incident" or "accident") is something ALL of us should be thinking about when deciding whether or not our cars are truly track worthy.

We've already seen cars on fire on a couple cars that hang around here.... These drivers were only lucky that they were okay and could get out of the cars. I'm always reminded of the "what if" that fire came after a bad crash where I couldn't help myself to get out - or if the door was jammed etc....

The horsepower and tires that are being built into ordinary street cars gives them the ability to carry some serious speed.... in most cases - far exceeding the drivers ability and the safety equipment required in many of these events. The speeds we're able to obtain at the end of some of the longer straights is astounding! Therefore - the likelihood of an "off" - or a brake failure - or a spin etc go up accordingly.

Some "incident" might have absolutely nothing to do with our own equipment - preparation - or skills. They might simply be because someone in front of us had an engine let go - or spilled the guts of their radiator....

Like I always told my kids -- "it's all a lot of fun.... right up 'til the time you get hurt". While that was more about football and soccer, and jumping bikes, etc.... it still rings true in our adult activities.

After reading about what happened, it seems the passenger side of the vehicle impacted, but the Passenger survived and the Driver did not. Makes me reconsider choice of seat, and HANS device usage on ANY track larger than Autocross...

Hello Chad,

Thanks for sharing the footage: ) It seems like the car and the driver have out grown standard HPDE events... Go on to NASA TT as you were talking about before. I think you will really like it. It's easier to grow and have fun when you have the carrot in front of you rather than being held up by traffic.

Regards

CurtiSS 69

Chad that was a great post on the event and I really enjoyed the video! That looks like so much fun and really motivates me to get my car finished.

The death at the track is a serious bummer. As Greg and others have stated...No One our ranks Major Safety.

It is a really unfortunate occurrence for sure. Some interesting threads spawned by this accident that really makes you think twice about how you approach these events.

Those are good points Greg. The level of safety preparation on this car was higher than my own (currently not hard to do) and higher than 90% of the cars I see on road course tracks at these types of events but it still wasn't enough.

I've been researching seats and hans devices again myself.

Thanks Curtiss. I've done more research on the Nasa TT events. Looks like a fun time but I'd never be competitive in most of the classes. I still think it might be worth trying and I've got my eye on the 2016 schedule.

Too true. Glad you enjoyed the video.

Hello Chad,

It is true that it would be tough to be competitive in TT on an individual event basis, but the car & driver development are priceless and fun. One other thing. You have a very reliable car, and look promising on the track. If you compete in most of the events you could be surprised at season closing. The cars in the higher classes commonly break; ) There's your first Ace. Keep your momentum going. We are all sorry Ivo is gone, but sometimes it just happens. Luckily these are not common occurances.

Regards

DEC