Side Sill Temp Graph - Some Surprises?

[Ron]

<FONT face="Comic Sans MS">Decided to take my daughter Tara out for a Easter afternoon Viper drive and put her to work recording side sill temps, speed and rpm:
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Some surprises for me at least

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<LI>Without any added venting, side sill temps decrease with speed
<LI>Engine speed (rpm) doesn't appear to have any temp impact if speed is sufficient
<LI>Idling, at least for 7 minutes or so, seems to reach a max temp then stabilize
<LI>Max side sill temp occurs by shutting off the engine immediately after a run.
<LI>Max temp isn't at the sill at all, but the frame member between the top of the sill and the closeout panel in front of the door.
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All temperature measurements were taken on the exposed sill screw head on the top of the sill behind the front tire. The temp probe was insulated in order to minimize any airflow cooling of probe. Of course, gear changes were used to maintain a constant rpm during speed changes and for rpm changes during a constant speeds. Ambient temp was 50 degrees.

Assuming my testing is accurate, conclusions can be that:

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<LI>Supplemental side sill venting is not absolutely required as natural airflow accomplishes the same effect
<LI>Letting the engine idle a bit after a run seems to cool down the cats and minimize side sill temperatures
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It would be great to see someone else either confirm or dispute my measurements.....

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[JetMec]

Well done, I like your findings. I'll stick with them considering I have neither the time nor the equipment to conduct this type of research. Though it's nice to know that there are people out there that are more anal about things than me.

 

[Steve-Indy]

Nice work, Ron. Interesting findings. Guess it re-enforces the concept of a "cool down lap" after a hard run...seems good for engines, brakes, turbochargers, AND sidesills!!!

 

[Ron]

<FONT face="Comic Sans MS">JetMec,

It's more of just a marketing guy wishing he took a few engineering courses. It's how I relax.....</FONT f>

 

[MES]

Nice graph, I like graphs

A random thought based on the airflow keeping the sills cool. How about a small electric fan mounted on the rear of each sill where the exhaust pipes exit? Keep you cooler in the summer driving around town

 

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ron:
[B<LI>Max temp isn't at the sill at all, but the frame member between the top of the sill and the closeout panel in front of the door.
[/B]<HR></BLOCKQUOTE>

Just before the side sill bulge, correct? That would be right where the cat is.

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[Matt M PA]

I too wondered about this, so last summer, using an infrared thermometer, i checked the temps of the sills after driving. I can;t remember the temps...somewhere around 190F..was the highest on the sill in the area above the inlet to the cat. I checked this in my garage out of the sun.

 

[BlackACR]

I have no cats at all & side sill vents. My sill temp at the most is not much over 90F. Can now drive around on a 90F day with out being in a sauna.

 

[GTS Dean]

Pull the side sill cover off and you will find that they get up into the neighborhood of 600F. This is referred to as "light-off temperature," which is where the chemistry of the gases change as they move through the catalyst media. The reason vehicles pollute more on cold start/short trips is that the system never gets sufficiently warmed up to work at design efficiency. Excess HC emissions are the primary result.

 

[JonB]

--Great Input, Ron ! You are certianly an asset here! Thank You.


-- While at the AZ-proving grounds last week, some of us received a tour of the "garage" area, where the SRT-10 and some neat 'others' were being tweaked. I was amazed at the numerous thermocouples attached to the sidesills and fender splash areas and nearby body panels of the SRT-10, and was told a LOT of hours were spent on all Vipers to research this concern.

-- The SRT is similiar, but the humongous cat of Gen 1-2 is gone; The new design is neat, simple, and apparently cooler.

-- The sill VENTS that are available facilitate flow at speed, but also provide for a convection inlet for a stationary car. Reducing pre-shutdown temps even further with vents should result in reduced geat-soaked temps. The "Heat Soaking" that you showed can also be helped by simply raising the hood and opening the doors after a spirited drive. I ALWAYS do this at track events.

GREAT STUFF, RON !