F40 rear air fence?

Sorry, but Sfumatos personal tirade was un-provoked. Those are the rules around here. Perhaps I know how to play by the rules. Im here. He isnt!

Now stop making a complete ass of yourself and get back to the poor people who have to wait whilst you publicize your personal hatred.

My asnswer to Scott.Mac's post was on-point, and is my opinion.

 

I take it you've never been banned ? oh, wait a minute.....

 

Back to work Jas, get back to work....

BTW, you have NOTHING to contribute to the topic towards Scott.Macs's original question as to "what is the purpose of the raised fence that some owners have added to the F40s bodywork..."

Here is a chance to stop your pathetically childish behavior. Go ahead, take this chance to get back ON TOPIC and say something meaningful about the stated question which is the basis of this thread. We are all waiting....

 

go back and read the thread....


I'll say it again, sfumato called you out repeatedly on your arrogance. You cried and got him banned, now its safe for you to come back in here and crow about it ? pathetic....

 

See ya Jas!

 

quoting yourself ? not surprising

 

On P 4/5 vs an Enzo improving air flow across the radiators and through the engine compartment lowered operating temperatures about 20 degrees. The key is enough outlet and smooth flow.

This isn't the first time Alberto, who supervised the modifications on the car referenced here, dealt with this. When I complained that my 1980 308 GTB was unable to cope with bumper to bumper on the West Side Highway in the NY summer we increased the radiator exit by cutting a vent into the front hood, a solution Ferrari saw and adopted on later cars. (See Photo) When Alberto was faced with a Gentleman Racer who was having a problem keeping the nose of his 333sp planted at the speeds he was driving which were slower than the car was designed to be driven he consulted with Micheletto and mounted an additional front fence/dam to help this customer who was more of a Gentleman than a Racer.

The idea that fences have to be adjustable to be effective is silly. The one Ferrari put on the trailing edge of the 599XX isn't nor are the ones Alfa put on the underside of 8C or Porsche put on the trailing edge of their SUV roof wing.
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Jim, stop misquoting me, and then taking your generalities as a highway for off-topic cruising.

I said that the specific fence, developed specifically by Michelotto, specifically for the the F40 LM, was intended to be adjustable to be effective for high SPEED adaptation with numerous circuits.

It was not placed there for anything to do with heating. If it was, please publish Michelotto's data accordingly.

Either way the bottom line goes back to my original response to Scott.Mac's original question: the air fence on an F40, is a COMPETITION (read: off-road, ie: track) application. Thats all Im saying. Dont misconstrue my position. I never said that "fences have to be adjustable to be effective" I simply observed that the fences put on street F40s were not even applied in the spirit and purpose in which Michelotto designed them in the first place: to be part of an adjustable rear airfoil system, which includes an adjustable rear wing.

 

Once again you're wrong. Post #8 quite clearly identifies the fence Scott was referring to as does the photo of it that you posted. Not only is it adjustable, the panel behind is slotted and the fence can be moved up and down, it and it's asymmetrical
counter part on the opposite side tune the air flow through the engine compartment vent directly in front of it which results in increased airflow through the engine compartment and better under hood cooling.
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Suit yourself Jim. I see a stationary fence. My premise remains the same. Fence on F40 = competition application, or else Ferrari SpA would have sent my street F40 with one on!

 

This fence,as I've said, is adjustable. The slot on the panel behind it allows it to be adjusted up or down to fine tune the flow through the engine compartment. When Alberto supervised WWOC's modification of this car, the car Scott clearly identified:

"Thanks, but, I meant the one on the car you guys were talking about on Ferraris online,
this fence:
http://www.ferraris-online.com/pages...68&imgnum=P005

With the huge wing on the F40, I was wondering how the small, rear vertical fence directly below it could possibly be contributing."

using parts developed by his friend Micheletto which considerably increased the HP of this Street driven F 40 the small Micheletto designed fences that Scott asked about were also added to increase engine cooling specifically because this car was going to be driven on the street at lower speeds and might otherwise overheat.

 

So it's okay for you to call people names? Good thing that Jas isn't so thin-skinned that he's going to go cry to Rob.

Sfumato will be back shortly... the truth hurts sometimes, doesn't it?

 

Show us the raw statistical data that proves your assertions that the fence benefits the F40 driven on the street. Go ahead. Im waiting to see... talk is cheap.

 

When Jas makes personal attacks, he is going to receive as good as he gives.

As for Sfumato, cant wait. But he wont last too long if he doesn't curb his enthusiasm for personal attacks on me.

Ciao.

 

"It is found that precise modeling of engine room outlet configuration is important to improve estimation accuracy of engine cooling air flow rate."

Title:
Numerical simulation of engine cooling air flow of a road vehicle
Authors:
Ukita, Tetsuji; Kataoka, Takuya; China, Hiroshi
Affiliation:
Mitsubishi Motors Corp., Tokyo (Japan).
Publication:
In Japan Society of Computational Fluid Dynamics, Proceedings of the 6th National Symposium on Computational Fluid Dynamics p 715-718 (SEE N94-34731 10-34)
Publication Date:
09/1993
Category:
Fluid Mechanics and Heat Transfer
Origin:
STI
NASA/STI Keywords:
AIR FLOW, AUTOMOBILES, COMPUTERIZED SIMULATION, COOLING FINS, FLOW DISTRIBUTION, FOREBODIES, HEAT RADIATORS, INCOMPRESSIBLE FLOW, NUMERICAL ANALYSIS, NUMERICAL FLOW VISUALIZATION, AERODYNAMIC COEFFICIENTS, COMPUTATIONAL FLUID DYNAMICS, ENGINE INLETS, FLOW VELOCITY, MATHEMATICAL MODELS, NAVIER-STOKES EQUATION, POISSON EQUATION, PRESSURE DISTRIBUTION, VELOCITY DISTRIBUTION, VORTICES
Bibliographic Code:
1993cfd..proc..715U

Abstract
A modeling method for a heat exchanger is presented to predict engine cooling air flow rate. The comparison between calculations and experiments confirms accuracy of the modeling method. A modeling of vehicle body configuration is also discussed. It is found that precise modeling of engine room outlet configuration is important to improve estimation accuracy of engine cooling air flow rate. By taking into account these modeling methods, it is expected that the under floor flow field of a vehicle will be estimated accurately. This enables the study on flow interaction between engine cooling air flow and under floor flow numerically, which has been difficult to obtain physical image experimentally.

 

found this picture in my files. (copyright of Dirk de Jager) This fence seems to run across the whole rear end...custom or factory?
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jim we all know he is just going to say that he doesnt trust mitsubishi. that you are misconstuing his post as he was talking specifically of the street f40. he wants something from Michelotto and until then he is still right. its a losing battle...

on a side note how on earth do you find this stuff?

 

All I can say is wow....

 

Turbo Charged Aircraft also have the same issues when flying at slow speeds. Note number 11 touches on this and any aerodynamic device that smooths turbulence at the engine compartment outlet would help to alleviate this. Also consider notes
9 and 10.

"11. Turbulence near or at cooling air inlets / outlet(s)

Additional cooling considerations

Flying at slower speeds or at high altitudes for turbocharged engine require more perfect cooling than faster moving aircraft with the same engine power. As mentioned earlier the air directed into the inlets is dependent upon the speed of the aircraft. Therefore, tow aircraft, floatplanes, fixed gear aircraft and other slower high power aircraft often suffer from more cooling problems.

Proper engine temperatures
Typical Continental engine temperatures should be: maximum oil temp 240°F, oil temperature 150-200°F, and maximum cylinder head temperature (CHT) 460°F. Suggested Lycoming engines temperatures are: CHT below 435°F in high performance cruise, CHT below 400°F in normal cruise, maximum CHT 500°F, CHT temperatures 150°F-435°F, maximum oil temperature 245°F, oil temperature 165°F-200°F. Check engine and aircraft Type Certificate Data sheets for exact limits on your particular engine / airframe combination. Hopefully your engine temperature indicators are ranged marked correctly.

Correcting engine cooling problems
A hot running engine has a shorter life-span due to elevated operating temperatures; this can be a tricky problem to fix on most aircraft.

Common air cooling problems
There are a number of things that can lower cooling air differential pressure and flow from engines:

1. Winterization components not removed for warm weather operations

2. Leaks between the cowling and air inlet / filter smaller carbureted engines

3. Cooling pressure leakage from baffling discrepancies due to wear, poor fit, out of position

4. Inadequate baffle seals and baffles. Gaps in baffles. Worn or short baffle seals.

5. Air leak around alternator, starter and ring gear (usually earlier Lycoming installations)

6. Inter-cylinder baffles that are not installed properly, gaps at bottom cylinder head fins, gaps at engine case, weak springs or insufficient support allow baffles to sag under air pressure.

7. Wrap around baffles improperly fitted and or are not secured properly

8. Insufficient pressure differential across cylinder fins

9. Insufficient draft and low pressure inside of cowling

10. Insufficient cooling air inlet or outlet(s) areas

11. Turbulence near or at cooling air inlets / outlet(s)"

 

You've answered your own question. "triple digit speeds perhaps?" with your "...or even worse icing on aerodynamic surfaces "

"Ice accretion on lifting surfaces will change their aerodynamic properties resulting in a reduction of lift, increase in drag and weight with a resultant increase in stalling speed and a reduction in the stalling angle of attack."

The stall speed of some Gliders is as low as 18 mph and even disturbances as small as bugs stuck on the wing can affect that.

The stall speed of a Cessna 180 for example is 59 MPH far from triple digit.

As Lee pointed out there's a reason that aerodynamic fences are used on Honda's, Toyota's, and Subaru's. They work quite well at low speeds. See photo of fence on SUV in post #25.

This was proved in the beginning of this thread. In aircraft Flaps increase lift at low/landing speeds. They are retracted at high speed.

As for "Holy sawzall Jim!" That's exactly what we used to cut the hood outlet into my 1980 308 GTB that after Ferrari saw it they copied in their later 308's. See post 107.

 

These modifications were done at the Behest of Marshall Field, under the Supervision of Alberto Pedretti, using parts developed by Michelloto for an F40 that was to be run on the street.

 

[More off-topic bickering deleted by mod.]