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Author Topic: "E" Gas Coupe Build  (Read 96982 times)
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MattGuzzetta
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« Reply #105 on: March 18, 2012, 11:57:15 PM »

Way to go making a fan shroud, it really makes the fan work.  When doing a one off part, I usually will make the master from urethane insulation foam which really shapes nicely and can be sanded to a good finish with about 60 to 100 grit sand paper.  Then use aluminum foil insulation tape (comes in 3"width) to cover the sanded foam (vacuum or blow off sanding dust first) and then paint the tape with PVA mold release (an alcohol based release agent). You can then fibeglass over the PVA.  The part will come off the "mold" and the PVA is water soluble so cleans up easily.  You then do a bit of sanding and maybe another layer of glass if you want the part stiffer in certain areas and you are good to go!   grin

You can also make the part directly on the body part you want to attach to and when you pop the piece off, you have a custom fitted part, no matter what the contour of the body part. (PVA on the body part as well so it comes off)

Hope that is a help to you and others who want to make complex parts quickly and accurately. 

Matt Guzzetta

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maguromic
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« Reply #106 on: March 19, 2012, 09:20:49 PM »

Matt, That sounds like a good idea, I will try it. Tony
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« Reply #107 on: March 22, 2012, 09:47:33 PM »

Today I received the shocks to design the suspension around  from Gentilozzi.  They are from his Indy car team and are the Ohlins 4-way adjustable. These should work great on this project as we are leaning towards a push rod style suspension. Like the roadster some parts dictate how the others part will work, and in this case the suspension will be built around the shocks. Before we do anything I will dyno the shocks to get a baseline and  go from there. Tony

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Jack Gifford
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« Reply #108 on: March 23, 2012, 12:04:27 AM »

What are the four adjustments?
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maguromic
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« Reply #109 on: March 23, 2012, 12:49:25 AM »

What are the four adjustments?

Jack, They are:

Low speed rebound - This helps with driver feel and helps keep the platform stable.  Going too aggressive will make the car feel harsh and choppy, finding the balance here is the key.

Low speed compression (bump) - This will help with getting the tires up to temperature quickly.  Basically it helps to control how the unsprung weight of the car is controlled.  Ideally you want to run as much as possible to where the car is not unsettled on the lager bumps on the salt.  

High speed rebound - This helps to control the spring and how the body is moving after hitting  larger bumps.  Here you want to run little as you have to so the car docent "jack down" while going down the salt.

High speed compression - Again here you want to run as much as you can get away with without going too stiff.  If you set it up too aggressive the car can launch when you hit the bigger bumps on the salt.

Walking around the pits I here people complaining how the car did this or that and the salt is bad.  In my opinion a majority of the time the car was not set up properly.  Every time the salt is bad there are a bunch of cars that go fast and set records. hmm  Tony
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Jon
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« Reply #110 on: March 23, 2012, 12:58:08 AM »

What spring frequency will you be aiming for Tony?

Thanks
jon
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maguromic
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« Reply #111 on: March 23, 2012, 12:15:40 PM »

What spring frequency will you be aiming for Tony?

Thanks
jon

You are asking for all the secrets.  cool

Since this car initially will be run in the Gas Coupe class, we are limited by aero aids and the setup will be a compromise of mechanical and aerodynamic grip. As you know there are many factors to consider and one of those parts is the tire info.  I am still waiting for the tire company to give the rubber compound and / or carcass construction info. Though I think it's hard to know in most cars, as the suspension components and tire spring rates are very significant and too often ignored.

We went to great trouble to measure those factors in  IMSA and Champcars. Since in this case we don't know the tire spring rate which will be a variable with speed or the chassis spring rate (and it's harmonic frequencies) , we really don't know a target frequency, and that's why the springs and shocks are adjustable.  But if I were to guess I would say somewhere around 3.0-4.5 Hz.  Tony
« Last Edit: March 23, 2012, 12:56:40 PM by maguromic » Logged

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krusty
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« Reply #112 on: March 23, 2012, 06:28:26 PM »



     More Guido parts!  Shocking!  grin  evil   vic
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maguromic
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« Reply #113 on: March 23, 2012, 06:49:21 PM »



     More Guido parts!  Shocking!  grin  evil   vic

Socking indeed!  grin evil Tony
« Last Edit: March 23, 2012, 06:51:23 PM by maguromic » Logged

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dw230
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« Reply #114 on: March 23, 2012, 08:38:34 PM »

I'm an old guy.

Tony and Krusty seem to be over engineering this shock rate, spring action, etc. stuff. Krusty has cred, Tony does too in other venues. I look forward to learning something new(to me).

DW
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maguromic
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« Reply #115 on: March 23, 2012, 09:23:06 PM »

DW, Its nothing new, just a way fine tuning the springs and shocks on the suspension and getting the correct relationship of spring rates to the tire vertical spring rate. The list of factors for properly selecting a spring is large and this lets us do it more easily. For us this is important as we  are horsepower limited compared to others and only by optimizing things can we expect to be fast.  This is the formula to get the natural frequency of one corner of the car. Frequency = (1 / (2 * Pi)) * Square root (Wheel rate / Sprung mass)  For all you closet math freaks, this is a pretty good explanation http://en.wikipedia.org/wiki/Damping

But there is a way around all this and its called horsepower as proven by one un-sprung roadster  shocked shocked shocked  Tony

« Last Edit: March 23, 2012, 09:27:31 PM by maguromic » Logged

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dw230
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« Reply #116 on: March 23, 2012, 09:55:17 PM »

Tony,

I know all that. But, as you well know in salt racing we weld the axles to the frame and horsepower through the next issue. Not as sophistegted (sp) as you are used to but, the records continue to fall.

DW
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« Reply #117 on: March 23, 2012, 11:46:03 PM »

After contemplating building our own wheel tubs or using a modified trailer fenders, I was able to find a shop that could build us a wheel tub in 16 gauge.  He was a little concerned about running it on his Pittsburgh and said he has done it before and the machine didn’t like him but he would get them done somehow by next week.  They will be 18” tall and 17” wide; this should also let us run the Dunlop’s at Elmo without issues.   Tony
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Tman
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« Reply #118 on: March 24, 2012, 12:01:48 AM »

Tony,

I know all that. But, as you well know in salt racing we weld the axles to the frame and horsepower through the next issue. Not as sophistegted (sp) as you are used to but, the records continue to fall.

DW


I am in this camp, thanks Dan. But, I dig the hi tech sheeot that Tony is bringing to the table!
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dw230
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« Reply #119 on: March 24, 2012, 10:23:34 AM »

I'm with you on that Trent. Tony brings a vast and varied background.

DW
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