Larger side vent opening

[ERA2076]

so you are building to 200 - wow.

He means at 200mph how many lbs per in^2 do you think the inside of the box will see? How much pressure is achieved above the 1.2 free stream you previously stated using a divergent box (plenum)?

At what speed does the box begin to make a significant difference in HP?

Will you road race or straight line?

If you are going to road race and can get there - hats off. It frightens just thinking about it.

you got a lot of work ahead of you to run that.

What are you going to do with the car?

Can't wait to see your aero?

x-chr

[ERA2076]

I did not realize you answered much of the above by embedding in an earlier post - thanks.

Fantastic you will wind tunnel. You are taking some risk.

Curious of your projected ground clearance with respect to your bottom aero.

Will the suspension geometry accommodate or would you possibly run a dropped bottom to get the right throat? What angle are you running your diffuser at?

Did you keep the trunk?

How will you handle the side pipes?

x-chr

[mikeinatlanta]

Originally Posted by ERA2076

I did not realize you answered much of the above by embedding in an earlier post - thanks.

Fantastic you will wind tunnel. You are taking some risk.

Curious of your projected ground clearance with respect to your bottom aero.

Will the suspension geometry accommodate or would you possibly run a dropped bottom to get the right throat? What angle are you running your diffuser at?

Did you keep the trunk?

How will you handle the side pipes?

x-chr

thanks, let's just hope I can do a decent cage.

Baseline for testing is 3.5" at front wheels and 4" at rear wheels. Low downforce configuration front tray slopes at 3 degrees. High downforce is much more complicated to answer. That is ground clearance for the metal. There are various pieces of sacrificial plastic that will be much lower.

The suspension is able to accommodate the desired ride height. Lower arms are level. The diffuser begins just aft of the cockpit an slope ranges from 0 degrees to 20 degrees. I'm asking nicely (for me) please no debate on the diffuser angles. Nobody on this forum has the technology to know exactly where or if I will suffer boundary layer detachment. Besides, if it does detach I'll just add an aft plane to hold it in place.

The standard FFR trunk bottom remains, however, correcting the FFR "perky butt" took away about 3" from the top, so not much trunk left.

Exhaust is a set of 1 7/8" - 2" somewhat equal length step headers with fully welded in 15 degree merge collectors with a 10 degree (I think) divergent cone. While the exhaust was fabricated by a master craftsman here in Georgia, the tube diameters, lengths, and all other internal specs were designed by SPD based on my exact motor specs. The fabricator was just the artist that made them fit and look amazing.


So, anyone have any pictures of late 60s race cobras with modified side vents? Good pics so far, but I'm still looking for the particular car.

[ERA2076]

Will the pipes be enclosed - shrouded - with the body? How will you handle the associated drag?

A cage to stiffen the chassis or a cage to survive a crash?

Can you hit 2000 lb with a full cage?

x-chr

[mikeinatlanta]

I'm done talking about the build. Anyone have any pics of late 60's race cobras with enlarged side vents?

[ERA2076]

I was reading "Shelby Cars in Detail" and came upon this. 2136,2137,2138 were prepped for Le Mans in 63. One of the changes was larger side vents. 2137 did not run at Le Mans, but the other two did. I think the car LMH posted early on could well be either 2136, or 2138 - one of them went to A.C.



FIA

[LMH]

The two Cobra's that raced at Le Mans in 1963 were CSX2142 and CS2131. 2142 was the U.S. entry and 2131 was the British entry (AC Cars). Both cars had larger side vents as well as aluminum fast-back hardtops. 2142 DNF and 2131 finished 7th. After the Le Mans race, 2136, 2137 and 2138 were completed and raced the remaining season but didn't compete at Le Mans in 63.
Larry

[ERA2076]

I went back and read it again - quite confusing. It does not say 2136 and 2138 ran at Le Mans. It says all three were built for Le Mans -. Then it says 2137 did not run there, but that two others did. I mistakenly assumed the other two were 2126 and 2138. I thought it strange A.C. would refit the Halibrands with Dunlops. I should have checked Shoens work.

Thanks for clarifying. -

The vents appear to be the same for both cars pictured.



I always look to see straking from the vents, but the white back ground says different.

[LMH]

It is a little confusing. I don't want to get too far off Mike's thread but for history sake, 2136, 2137 and 2138 were modified to Le Mans specs and were listed in AC Cars records as "Le Mans Replicas". There were a total of six cars modified to Le Mans specs, not including the two original race cars 2142 and 2131. According to the registry, 2136 was shipped to the USA on June 27, 1963. The 63 Le mans race took place on June 15-16, 1963. Built too late to compete at the 63 24 hours. It's first race was at Road America in September, 1963.
Larry

[mikeinatlanta]

Thanks for the pics. Not quite the one I was thinking of but I think they will work fine. Once again, thanks.

[ERA2076]

There is a picture somewhere of one of the actual Le Mans cars drooling oil out the drivers side vent and it is streaking downward as it is sitting in the pits during the race. Is it possible the vents are in fact venting being pulled by a pressure differential under the car? I ask because the 99 car above has some kind of drool coming out of the vents and appears to be pulled down.

x-chr

[mikeinatlanta]

I settled on the Lemans car style enlarged vents, but went with a size better suited to my needs. To those who helped by answering my original question rather than judge and critique, thank you.

First is cutting out the body bigger. I went with a vent the same length as original, but considerably taller.


They aren't fully mounted yet, but here is the new custom side vent mocked up.

[LMH]

Looks pretty good!
Larry