HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Suspension balance is a concern

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Suspension balance is a concern

Post  cfgioja on Thu Jul 29, 2010 1:21 pm

I know alot of us are trying to get as close to a 50/50 setup as possible, since the idea of being in balance seems the best way to go.

I was reading a pamplet on the Nissan 370Z and it describes the engineers moved the weight to a 53/47 setup. this is done for a couple reasons as they describe.

When entering the corner the weight shifts forward to keep good grip on your front tires for steering.

Then when punching throught the apex of a corner and you get on the gas, the weight shifts backwards leveling the car to a 50/50 balance creating a good balance and to allow nice grip for control on all four tires.

Thought it was a good piece of information.
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Re: Suspension balance is a concern

Post  Porch on Thu Jul 29, 2010 1:49 pm

What Nissan meant to say is that, when they were ripping off everyone else's designs and technology, they ended up with a 53/47 weight balance.

But other than that...the Miata has a 50/50 weight balance and i think there would be no dispute that it's an awesome road and autoX car.
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Re: Suspension balance is a concern

Post  Dawgz83948 on Thu Jul 29, 2010 2:00 pm

What Nissan said is true to a point. However in a turn you are typically not on the gas hard enough to cause any weight shift rearward. In a turn your chassis is basically building g's to the side, so you want 50/50 so it pulls in a balanced way. I'm going to wait and see if Nissan wins any races from Porsche BMW before their engineers counter decades of racing knowledge.
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Re: Suspension balance is a concern

Post  962porsche on Thu Nov 04, 2010 10:05 am

when it comes to the balance on a car there are allot of factors that come into play . when most people talk about the balance of a car being 50/50 its static balance . (1) no car realy is they maybe close like the miata and 924 , 944 and 928 . what people are talking about is the static balance of a car . when a car is rolling you can throw out the static balance rule . thats becouse of pitch , roll and yaw them there is the laminar flow of the air going over and under a car along with what downforce the car will generate . any one and all these things radically change the balance of a car once moving . i found that the 944 along with the miata's will turn a faster lap with more weight static balanced to the rear of the car if its a none winged and splitter body car . its very ez to get rear downforce on a car but so much for the front of a car . the front spliter will and do add some but 80% of the spliters out there on cars don't work all that good becouse of there design . a front spliter that realy works is allot more than a flat piece of ? sticking out from under your bumper . that kind of splitter is usless and don't work at all . once you add a rear wing (or spoiler) to a car and front spliter you have to change the static balance of the car to compensate for its downforces . when we set up our and customers race cars we first set them up with no downforce added in 0 wing angle no front spliter . then we do front first (as stated before is ez to get rear downforce into a car) splitter angle , size and shape . then dial in rear wing to get the total balance of the car . after that we than put the car back on the scales and see just what the static balance is . most of the time the car will have more nose weight becouse of the rear wing size and angle it has . the key word is most ! with the 944 v8 i have the car has 51% nose weight with it at a static balance becouse of the size and angle of the rear wing we are using . getting into the corning of a car and the weight . you want your car to beable to run at about a 10% slip angle in a corner thats from turn in to track out . you can push it up to a 15% slip angle but the 944 will burn up tires allot faster if you set the car up to run at a 15% slip angle . this is just a general rule and there are also other factors that come into play like does the car have a fuel cell or stock fuel tank . thats becouse fuel in a stock fuel tank has about 7 LBS per GAL. of inertia balance that has acting forces on a car in its pitch, roll and yaw .
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Re: Suspension balance is a concern

Post  cfgioja on Thu Nov 04, 2010 12:42 pm

well you seem ahead of me in tthe mechanical engineering and pyshics departments. I do unerstand what you are saying.

My question for you is, when figuring down forces of a spoiler/splitte/diffusor, wether front or rear. Do you not need a wind tunnel to test these or is there a set of calculations some where to figure it all out?
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Re: Suspension balance is a concern

Post  962porsche on Thu Nov 04, 2010 2:32 pm

my schooling was in aerodynamics and chassis . a full size windtunnel would be great if you had a $#** load of money to rent one . trail and error is what it comes down to . there is no real calculations that you can do becouse there are so many variables . this is why we start with the car using no downforce other than what the body has to offer . rear deffusers are great if the car is a tunnel car or flat bottom car if its not then they don't work all that well . deffusers will give the most downforce with the least amount of drag aka CD . a deffuser also is more linear forces as speeds increase the amount of down force increases at the same rate . unlike a wing . a rear wing will not give the same linear downforce as speeds increase . becouse of the frontal of the 944 being flat they do benefit from a spliter . the front splitter should be about 10% of the total hight of the frontal vertical hight of the nose on the car . but its more that just that . there is also the under side of the spliter to add in .most spliters just end under the bumper of the car . and are also just flat . on the under side of leading edge there should be a little ridge that runs along the front . the splitter should also run as far back under the car is it can go . most of the time stopping about at the front axle center line . it would be great if you could run the spliter to the fire wall but you need to let the incoming air out of the engine compartment .


Last edited by 962porsche on Sun Nov 07, 2010 6:45 am; edited 1 time in total
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Re: Suspension balance is a concern

Post  cfgioja on Thu Nov 04, 2010 5:51 pm

I will do some research on my own, but what is the differences between a splitter and diffuser on the front of a car? what are these batwings considered? I have seen cars with little wings on each fender and cars like nascar with what looks like an adjustable batwing.
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Re: Suspension balance is a concern

Post  962porsche on Thu Nov 04, 2010 6:55 pm

McGraw Hill has some very good reads on aerodynamics . i don't know if you read racecar engineering mag. its a real good magazine to read . they had a good write up on wings back in august 2010 they may have some back issues still for sale . deffusers are in part used on the under side of a car to do just that deffuse air flow exiting from the car . the bat wings are called dive plains or canards . they are for high speed cornering . most are ajustable to fine tune the aerodynamic forces on the nose of the car . a spliter is on the front of the car to split the air giving a high pressure and low pressure like a wing would do on the back of a car . allot of times people will just start putting wings and spliters on cars not knowing about them and then tell you how good they work . i found a single plain wing is best for the 944 body cars . and a front splitter that is about 4 1/8" inchs long from the front bumper works best with the spliter going to the front axle center line and a 3/16 " half round bump on the under side of the leading edge .
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