License plate stand off....
- Thread starter MAD IN NC
- Start date
Although I too am a fan of the aluminum stand-offs, I'll be the first to say that faster is not *always* better :biggrin For verification, we can probably ask one of the blondes or redheads.
Regarding the license plate stand-off and the effect, or lack thereof, for heat dissipation, I'm not really sure that any static tests are going to tell us much. At the root of this, what we are interested to know about is the "air management" of the flow of air into and out of the engine compartment. By design, the GT is capable of ingesting large volumes of air through the side scoops at speed. How the air gets in is pretty obvious. Also obvious upon inspection, is that the side scoops represent just about the ONLY means of ingesting air. With a sealed undercarriage, no air is coming up from underneath the car. But, more importantly, we are interested in how the air gets OUT of the engine compartment - and if there's a demonstrable way to improve that.
As I see it, there are three main ways for the ingested air to exit. Keep in mind that this is really important because the exchange of external (cooler) air in place of the hot engine air IS linked directly to the car's ability to expel the heated air. So, we have the side vents around the rear window, we have the area to either side of the license plate and the plate area itself, and we have the area below the bumper.
Conceptually, it would seem that most of the air flows out the lower section below the bumper. This would appear to be the largest of the openings and it is also the least obstructed when a stock muffler is in place. So, I would think that the license plate stand-offs are going to be helpful (they sure aren’t going to hurt), but they are likely going to be more effective when a large rectangular obstruction is not placed just in front of them.
Regarding the license plate stand-off and the effect, or lack thereof, for heat dissipation, I'm not really sure that any static tests are going to tell us much. At the root of this, what we are interested to know about is the "air management" of the flow of air into and out of the engine compartment. By design, the GT is capable of ingesting large volumes of air through the side scoops at speed. How the air gets in is pretty obvious. Also obvious upon inspection, is that the side scoops represent just about the ONLY means of ingesting air. With a sealed undercarriage, no air is coming up from underneath the car. But, more importantly, we are interested in how the air gets OUT of the engine compartment - and if there's a demonstrable way to improve that.
As I see it, there are three main ways for the ingested air to exit. Keep in mind that this is really important because the exchange of external (cooler) air in place of the hot engine air IS linked directly to the car's ability to expel the heated air. So, we have the side vents around the rear window, we have the area to either side of the license plate and the plate area itself, and we have the area below the bumper.
Conceptually, it would seem that most of the air flows out the lower section below the bumper. This would appear to be the largest of the openings and it is also the least obstructed when a stock muffler is in place. So, I would think that the license plate stand-offs are going to be helpful (they sure aren’t going to hurt), but they are likely going to be more effective when a large rectangular obstruction is not placed just in front of them.
UPDATE - Temperature readings
When I started this task the thought was centered around allowing more ventilation when driving of the engine compartment which we all know can be a scorcher...
Last weekend I spaced the license plate 3/4 from the back valance and noticed an increase in outside heat after driving the car where the plate was hotter and even the license plate lights were I felt hotter than normal.
Today I brought home a temperature probe and made the following measurements over three scenarios.
Baseline - Outside temperature 67.2F (great day after Ernesto visited us)
Car temp - ~190F per guage
Same trip over three test scenarios (6.2mi.)
#1 - Plate on valance, as is from Ford, No additional airflow relief (stock)
Temp on plate - 112F
Temp on License plate lights 100f
#2 - 3/4 in. bushings added on all four license plate screws
Temp on plate - 133F
Temp on License plate lights 160f
#3 - 3/4 in bushing ONLY ON TWO LOWER SCREWS, top of plate and screws mounted flush to valance.
Temp on plate - 112F
Temp on License plate lights 100f
Summary: After driving when license plate is "stood off" from valance, radiated heat rising from rear of car increases temperature on license plate lights and facia trim....
If you allow spacing on only the lower part of the plate, when driving it will increase air flow of engine compartment but the radiated heat when car is parked will not radiate upwards into the license plate lights and facia as top of plate is flush mounted across length of valance.
So, I have placed 3/4 spacers (aluminum) behind only the bottom two license plate mounting screws and have same radiated heat thermal characteristics as a solid plate when parked but when driving allows more air flow.
I have not probed the engine compartment when driving but with the stock muffler I know it is 20F hotter in the engine compartment than an Ida or Accufab exhaust setup (which is the next upgrade if I don't go the TT route!)
:cheers
When I started this task the thought was centered around allowing more ventilation when driving of the engine compartment which we all know can be a scorcher...
Last weekend I spaced the license plate 3/4 from the back valance and noticed an increase in outside heat after driving the car where the plate was hotter and even the license plate lights were I felt hotter than normal.
Today I brought home a temperature probe and made the following measurements over three scenarios.
Baseline - Outside temperature 67.2F (great day after Ernesto visited us)
Car temp - ~190F per guage
Same trip over three test scenarios (6.2mi.)
#1 - Plate on valance, as is from Ford, No additional airflow relief (stock)
Temp on plate - 112F
Temp on License plate lights 100f
#2 - 3/4 in. bushings added on all four license plate screws
Temp on plate - 133F
Temp on License plate lights 160f
#3 - 3/4 in bushing ONLY ON TWO LOWER SCREWS, top of plate and screws mounted flush to valance.
Temp on plate - 112F
Temp on License plate lights 100f
Summary: After driving when license plate is "stood off" from valance, radiated heat rising from rear of car increases temperature on license plate lights and facia trim....
If you allow spacing on only the lower part of the plate, when driving it will increase air flow of engine compartment but the radiated heat when car is parked will not radiate upwards into the license plate lights and facia as top of plate is flush mounted across length of valance.
So, I have placed 3/4 spacers (aluminum) behind only the bottom two license plate mounting screws and have same radiated heat thermal characteristics as a solid plate when parked but when driving allows more air flow.
I have not probed the engine compartment when driving but with the stock muffler I know it is 20F hotter in the engine compartment than an Ida or Accufab exhaust setup (which is the next upgrade if I don't go the TT route!)
:cheers
TEXAS GT
2006 Twin Turbo
I'm no engineer, but I don't really see where the temps of the plate tell us much about the effectiveness of the increased airflow. The object is to lower engine bay temps so it seems to me that the only important reading would be of actual temps taken inside the bay before and after spacing the plate. Can this be done while driving?
AMB
GT Owner
LP Standoffs
I believe the temp went DOWN with the spacers ONLY in the bottom plate, was because of the better airflow out the bottom with the plate angled !!! (less restrection) With the spacers in both upper and lower, the air just hits the plate and defuses everywhere. (more restrection)
AMB
I believe the temp went DOWN with the spacers ONLY in the bottom plate, was because of the better airflow out the bottom with the plate angled !!! (less restrection) With the spacers in both upper and lower, the air just hits the plate and defuses everywhere. (more restrection)
AMB
Guys, the temparture issue I was fighting was the "radiant temp issue" when the car was parked after a drive.
If you stand off all 4 plate screws the heat naturally disapates into the top of the license plate and valence where the license plates lights are and the plastic facia is on the back end of the car.
With the license plate offset (tight mount on tops and 3/4 spacers on bottom) it will allow more air to be removed from the engine compartment when you are moving as there is airflow.
Try what I tried over the three tests- all you have to do is "feel" the lights and the plate......
If you stand off all 4 plate screws the heat naturally disapates into the top of the license plate and valence where the license plates lights are and the plastic facia is on the back end of the car.
With the license plate offset (tight mount on tops and 3/4 spacers on bottom) it will allow more air to be removed from the engine compartment when you are moving as there is airflow.
Try what I tried over the three tests- all you have to do is "feel" the lights and the plate......
fjpikul
GT Owner
Engineers! Just "feel" the plate. Where's my lawyer after it gets scorched. I don't know why you just don't mount a hot dog with a probe in it.
jasper
GT Owner
brain wave
i know i'm not a engineer, don't wanna be one either but i have an idea,
as kendal explained, ya got to get rid of the hot air right, well , those cars
fitted with aftermarket exhausts have a lot more room, right, well why
couldn't thermo fans be fitted, with a thermostat under the clamshell, fit
the fans below the bumper, might work might not.
like that chinese bloke consfuses say food for thought
i know i'm not a engineer, don't wanna be one either but i have an idea,
as kendal explained, ya got to get rid of the hot air right, well , those cars
fitted with aftermarket exhausts have a lot more room, right, well why
couldn't thermo fans be fitted, with a thermostat under the clamshell, fit
the fans below the bumper, might work might not.
like that chinese bloke consfuses say food for thought
Well, I think this thread has become a little confusing because some of us have been more concerned with expeling the hot under-hood air while underway while othere are more intrested in how to help the GT cool down while it is stopped. Frankly, other than the fan idea, I don't think there's anything we do to assist cool down. With no air moving at all, the hot air is simply going to go up, and out the vents on the top of the clamshell. I think the license plate spacers would only be very, very marginally effective in this stand-still scenario.
However, the equation changes when the GT is underway and now we're talking about a more complex set of interactions. The GT is literally "scooping" air into the engine-bay, so it also has to effectively find a way to pass this incoming air out.... and maintain the rotation of outside air in place of the heated engine compartment air. Conceptually license place spacers can be effective in this scenario and help with engine-bay temperatures and heat-soak avoidance.
However, the equation changes when the GT is underway and now we're talking about a more complex set of interactions. The GT is literally "scooping" air into the engine-bay, so it also has to effectively find a way to pass this incoming air out.... and maintain the rotation of outside air in place of the heated engine compartment air. Conceptually license place spacers can be effective in this scenario and help with engine-bay temperatures and heat-soak avoidance.
Red Rocket
GT Owner
engine compartment heat - use a heat wrap
One solution I have not seen posted yet is something people might want to consider. One can get 'heat wraps' for the exhaust & muffler can. Just so you know, heat management is a racer trick for gaining horsepower cheaply. Instead of trying to remove the heat, they try to manage it better. For example, wrapping the muffler deflects the heat out of the engine compartment - if done correctly - and by keeping the heat in the exhaust system it helps HP. Also, if done right it can be quite attractive to look at.
Before I get an avalanche of questions how to do this, I have not tried it on my GT yet. I suggest anyone who wants to explore this check with a qualified SVT tech who also understands racing tricks.
One solution I have not seen posted yet is something people might want to consider. One can get 'heat wraps' for the exhaust & muffler can. Just so you know, heat management is a racer trick for gaining horsepower cheaply. Instead of trying to remove the heat, they try to manage it better. For example, wrapping the muffler deflects the heat out of the engine compartment - if done correctly - and by keeping the heat in the exhaust system it helps HP. Also, if done right it can be quite attractive to look at.
Before I get an avalanche of questions how to do this, I have not tried it on my GT yet. I suggest anyone who wants to explore this check with a qualified SVT tech who also understands racing tricks.
- Aug 25, 2006
- 4,436
Red Rocket said:
It is about time this was brought up.
I chatted with a John at AccuFab last week and ordered the pipe and shared with him that I am going to thermal insulate the interior of the pipe and then wrap the exterior because over the years I have found this to be very effective particulalry in the mid/rear engine gals of several Marquees
Furthermore; whether the license plate stand-offs help for cooling is at best an interesting question without some real time data collected and yet the plate and surround area temperatures with them in place is expected because akin to a blow torch now the hot ait in fact wil stream past the plate, license plate lights, etc. ...good...bad... I have yet to decide and yet Kendall shared with me that his premise was that the stand-offs help to keep the paint around the plate based on the OEM mount design from becoming damaged; now this alone makes sense to me.
Lastly; it would seem to me that any one of the GT's build team that visit this board could answer this question too.
Takes care
Shadowman
Last edited:
- Aug 25, 2006
- 4,436
eshrink said:
The team at Jet Hot and HPC offer a great variety of services; when it comes to the coating often times folks want the bright stainless as such a thermal coating can b placed on the inside. It is begins as a liquid that is poured into the pipe and then insures for full covered and then is baked to cure unliked the spray coating process that is difficult at best to get throughout the inside. This process works very well for headers that do not have cats behind them or in the case of the AccuFab exhaust for the GT where the section being replaced is post cats.
Shadowman
ByeEnzo
GT
Red Rocket
GT Owner
Shadowman, if you have the capability it would be of great interest if you could measure the horsepower and temps before and after the changeover to the X pipe with the thermal insulation. [By now I guess we're all wishing we had a dyno installed in our homes!]
Maybe the nice gents at Accufab might be willing to do it for marketing purposes (how about it George?). BTW here's a plug from a non-related party (me) - they are always willing to offer advice and help, and they have considerable experience with the GT
Maybe the nice gents at Accufab might be willing to do it for marketing purposes (how about it George?). BTW here's a plug from a non-related party (me) - they are always willing to offer advice and help, and they have considerable experience with the GT
- Aug 25, 2006
- 4,436
Maybe the nice gents at Accufab might be willing to do it for marketing purposes (how about it George?). BTW here's a plug from a non-related party (me) - they are always willing to offer advice and help, and they have considerable experience with the GT[/QUOTE]
I replied to this earlier however during the upload process it locked up so here is round 2
Let me share that when I chatted with John at AccuFab last week prior to ordering my exhaust piece I explained to him my intention. He asked me if I had any concerns with the pipes cracking after insulating/wrapping them to which I said “no, I have had no issues in many years”. I have found that when used on pieces that are behind the cats there is no captured heat furthermore the temperatures by the time is reaches that portion of the exhaust are significantly reduced because they are so far away from the source. Having shared this when we first began using the external wrapping process on headers many years ago we did have issues from time to time but felt that the benefits devired offset the cost; FYI this was done on race cars..
Now this brings me to the issues as to where insulating/wrapping will produce more HP. The answer to this question depends on who you ask however technically speaking yes because by keeping more of the heat within the tube the exhaust maintains a higher flow speed as such the process should promote better cylinder scavenging. What I mean is the ideal situation is for the cylinder to fill fresh and clear out completely after every firing cycle however in most case this is not the case so if you can visualize the supercharger pushing the mix into the cylinder then visualize the exhaust (ideally) as more than simply an exit point but rather an assistant to the power producing process. The pulses between cylinders create a vacuum of sorts within the exhaust hence the term extraction …… or in the case of exhaust some are referred to as an extractor because they are designed to maximize the use of the pulses thus creating the greatest vacuum possible. Do I feel that this insulating/wrapping will produce any measurable gains on the GT based on the overall design of the OEM exhaust; no.
Now as for HP reading before and after; sadly this will not happen for two reasons;
1. My gal does not have enough miles on her for me to consider doing a WOT Dyno pull
2. Furthermore; I am not an advocate of Dynoing for numbers; there are far too many variables that skew the numbers. The only time I place a gal on the Dyno is when tuning.
Here is what I know from experience;
The removal of the muffler will in fact by default reduce the radiant temperatures because there is no longer a can holding and radiating heat to deal with; all that remains are the flow through gasses. I also know that whether insulating the inside of the tubing and or wrapping the exterior will further reduce the radiant temperatures however; as with an older style wall heater in one’s home it will slow the process however the radiant energy will still be there coming from the other sources one of which are the cats which are located at the end of the gal and get “EXTREMELY” hot and by design are radiant cans and are truly the most significant heat radiating pieces within the engine bay.
Here is my opinion based on similar conversions that I have done on my Lamborghini’s and Ferrari’s.
When the gal is at speed the cause and affect of the radiating heat generated within the engine bay is minimal at best because the air exchange rate when driving is significant and comparatively speaking constant as such the engine bay will come up to a temperature and then remain fairly constant in same manner as your water and oil temperatures. However; when the gals are sitting in traffic and being driven in a stop and go manner this issue changes drastically because during these times the air exchange rate within the engine bay is little or none as such the ever increasing radiant heat becomes as issue until such time as heat soak sets in at which time you have a BBQ on wheels back there. Certainly once the gal is at speed again the temperatures drop quickly however during those heat soak periods is when close proximately items such as the rear body panels, the rear bonnet particularly the plastic vents will be at risk for cosmetic damage over time.
One such an example would be the Ferrari 360’s that were purchased with the solid painted rear panel. When these cars were used as put puts around town the captured heat was so great that the rear taillights would melt. The remedy was to install the optional rear Challenge grill which is a steel mess that would simply allow during those times the air to circulate a bit more and the results were no more (almost) melted tail lights.
So I close by adding to this the comments that have been made about spacing the rear license plate (all four corners or just the lower two corners) and whether it will afford any measurable benefit; I feel that it will afford a reduction of the amount of heat transferring to the close proximity painted area and as described with the Ferrari rear Challenge grill because it will become by default the path of least resistance hence another means for the accumulating heat to escape during stop and go driving however when at speed I suspect it affords very little mechanical benefit. Having shared this; yes I am installing them on my gal as well.
Sorry to ramble
Shadowman
I replied to this earlier however during the upload process it locked up so here is round 2
Let me share that when I chatted with John at AccuFab last week prior to ordering my exhaust piece I explained to him my intention. He asked me if I had any concerns with the pipes cracking after insulating/wrapping them to which I said “no, I have had no issues in many years”. I have found that when used on pieces that are behind the cats there is no captured heat furthermore the temperatures by the time is reaches that portion of the exhaust are significantly reduced because they are so far away from the source. Having shared this when we first began using the external wrapping process on headers many years ago we did have issues from time to time but felt that the benefits devired offset the cost; FYI this was done on race cars..
Now this brings me to the issues as to where insulating/wrapping will produce more HP. The answer to this question depends on who you ask however technically speaking yes because by keeping more of the heat within the tube the exhaust maintains a higher flow speed as such the process should promote better cylinder scavenging. What I mean is the ideal situation is for the cylinder to fill fresh and clear out completely after every firing cycle however in most case this is not the case so if you can visualize the supercharger pushing the mix into the cylinder then visualize the exhaust (ideally) as more than simply an exit point but rather an assistant to the power producing process. The pulses between cylinders create a vacuum of sorts within the exhaust hence the term extraction …… or in the case of exhaust some are referred to as an extractor because they are designed to maximize the use of the pulses thus creating the greatest vacuum possible. Do I feel that this insulating/wrapping will produce any measurable gains on the GT based on the overall design of the OEM exhaust; no.
Now as for HP reading before and after; sadly this will not happen for two reasons;
1. My gal does not have enough miles on her for me to consider doing a WOT Dyno pull
2. Furthermore; I am not an advocate of Dynoing for numbers; there are far too many variables that skew the numbers. The only time I place a gal on the Dyno is when tuning.
Here is what I know from experience;
The removal of the muffler will in fact by default reduce the radiant temperatures because there is no longer a can holding and radiating heat to deal with; all that remains are the flow through gasses. I also know that whether insulating the inside of the tubing and or wrapping the exterior will further reduce the radiant temperatures however; as with an older style wall heater in one’s home it will slow the process however the radiant energy will still be there coming from the other sources one of which are the cats which are located at the end of the gal and get “EXTREMELY” hot and by design are radiant cans and are truly the most significant heat radiating pieces within the engine bay.
Here is my opinion based on similar conversions that I have done on my Lamborghini’s and Ferrari’s.
When the gal is at speed the cause and affect of the radiating heat generated within the engine bay is minimal at best because the air exchange rate when driving is significant and comparatively speaking constant as such the engine bay will come up to a temperature and then remain fairly constant in same manner as your water and oil temperatures. However; when the gals are sitting in traffic and being driven in a stop and go manner this issue changes drastically because during these times the air exchange rate within the engine bay is little or none as such the ever increasing radiant heat becomes as issue until such time as heat soak sets in at which time you have a BBQ on wheels back there. Certainly once the gal is at speed again the temperatures drop quickly however during those heat soak periods is when close proximately items such as the rear body panels, the rear bonnet particularly the plastic vents will be at risk for cosmetic damage over time.
One such an example would be the Ferrari 360’s that were purchased with the solid painted rear panel. When these cars were used as put puts around town the captured heat was so great that the rear taillights would melt. The remedy was to install the optional rear Challenge grill which is a steel mess that would simply allow during those times the air to circulate a bit more and the results were no more (almost) melted tail lights.
So I close by adding to this the comments that have been made about spacing the rear license plate (all four corners or just the lower two corners) and whether it will afford any measurable benefit; I feel that it will afford a reduction of the amount of heat transferring to the close proximity painted area and as described with the Ferrari rear Challenge grill because it will become by default the path of least resistance hence another means for the accumulating heat to escape during stop and go driving however when at speed I suspect it affords very little mechanical benefit. Having shared this; yes I am installing them on my gal as well.
Sorry to ramble
Shadowman