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Hi everyone!

Well I have been getting squashed by the admins at scionlife over a front bumper mod I have done for scientific reasons to my front bumper.

Lemme give you some background-

I bought my XB at Christmas time, for a while after driving it I smelled very hot rubber when exiting the vehicle, I thought it smelled a little like coolant so I took it in to the dealer who pressure checked the system and said nothing was leaking- after this I was relieved until I pulled over that day and got out of my car and the same strange hot-rubber and plastic smell was there.

After thinking about this for a while and examining my engine and radiator I realized that it was the front bumper blocking the airflow into the engine compartment. This was made very evident by the oily dirty stains on my radiator that only went up about 27% of the way from the bottom of the radiator which meant that the rest of the air was being deflected somehow by the factory grill and bumper assembly.

After examining the angle of the deflection on top half of the front bumper, I realized what was occurring- the air was not being allowed to enter the front grill at highway speeds effectively by the angled air being deflected by the top half of the bumper and when it passed sideways across the "holey grill" it just passed over the grill holes instead of through them. The top half of the radiator was showroom clean, while the bottom 27% was road stained. The hole pattern seemed to help this effect along by creating something in the aerospace industry known as VC's or Vortex Creators, channeled walls of resistance that create a V pattern across the grill and set up channels of resistance to air entry. Now either this was a huge mistake in styling or a really good design for automation controls failure.

I calculated that the plastic blunt-nosed design had to be modified or all the sensors and wiring in my engine compartment might get hosed by the heat build-up which is what was causing the smells. I noticed the engine compartment was sealed almost entirely, with rubber gaskets and closed fenders and the exhaust manifold set in the middle like a HUGE heater cooking all the hoses and wiring around it which are already hardened and softened by the heat exposure after only 6500 miles!!

I recommend that the hood directly above and extending back from the exhaust manifold be louvered to let the heat escape up and out of the engine compartment as well, well mainly because heat rises, lol.

I measured out with a dry-erase marker, and left myself 4cm down the middle for plastic bumper lip support cut 2 holes as neatly as possible leaving 1cm of material around the edges for trim, calculating the angle of air entry past the holes and just big enough to directly hit the radiator with cooling air at highway speeds. The two holes had a forward-facing profile of 28cm x 8cm which would allow 1.1 million cubic cm (or 38.8 cubic feet) per second into the engine compartment per second at 55 MPH.

Did I mention that I am a scientist?

Anyways- I tried out the "MOD" for 2 days and the smells dissapeared entirely. Now the admins from the other site said this was due to additional air, and now I gotta say he's right, it is a lot of additional air right where it's needed most.

I will post diagrams of the mod sometime today with details on measurements.

I have not put "grill" material over my holes yet- I haven't found any that don't block the airflow, maybe I'll channel the two holes with a "scoop" look in fiberglass or just trim the holes in black rubber edge trim.

Free the XB, make it the longest lasting, coolest car on the road!

Zio
 

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Thanks for sharing your efforts, I read your post the other day, some seem to think you were off base, I don't.
What you are saying makes sense, it's got to get hotter than hhhh in that compartment.
When you post the final chapter I will get the info, I think I would need a good shop to do the work, I would like to know how you trim the opening and what the cost is for the louvers.
Many moons ago we had a patrol with the interceptor, overheating was a problem we solved it by putting forward and aft boat scoops on the hood, looked weird but worked well.
Thanks again
vanhool2045
 

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i'd like to see the finished product as well.

Sounds like something i would do to my xB.

cuz i was thinking something like this...



but i don't want to mess anything up and i want to make it look good.
 

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callmemrbill said:
Forgive me for sounding dumb. But are the 2 mesh sections on the front the MOD?
My understanding is that you cut out holes in your front bumper to allow for better airflow and the mesh is there to cover up the holes and make it look cool.
 

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Well that makes sense. It looks awesome. This is something I would be interested in. I have checked the ebay listing and just might be doing this. I don't want issues down the road.
 

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callmemrbill said:
Well that makes sense. It looks awesome. This is something I would be interested in. I have checked the ebay listing and just might be doing this. I don't want issues down the road.
what is strange is the ebay listing does not even say what the grille pieces are for or what they are supposed to do? :confused:
 

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Very Nice Zio. Reading the article again and checking out the auction I am seriously considering doing this. I want more power and want the the electrical and hoses to last as long as possible. I don't want to be replacing things earlier than I have to. Maybe you have come up with something they will work into the future models.

BTW Zio, I moved here to Salt Lake City about 3 years ago from Marysville, WA. I lived in the NW for 26 years.
 

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To whoever is considering this modification,
Over the years I have been involved in flow dynamics and aerodynamics, and I feel that this modification could actually cause long term heat related problems. This was discussed to some length on the scionlife forums. The poster did not properly test this modification, and does not understand flow dynamics. There is a very real possibility of a what is termed "turbulant blockage" where a
non-laminar airflow can actually block air from going through a screened surface such as a radiator. The placement of the modification holes could disturb the laminar flow over the air deflector in front of the radiator, causing turbulant blockage. Linear airflow is much more important in a cooling environment than mass turbulent air, which can create a pressure blockage through a grid (radiator) which can actually decrease airflow.

On the scionlife forums, the original poster refused to listen to the opinions of those that study and work with flow dynamics about what issues can occur without proper testing, and instead resorted to name calling and attempting to belittle those that tried to help and warn others of possible problems with this modification. It got bad enough that threads were locked, messages deleted and the original poster was made to stop trying to sell or link to his ebay ad on scionlife's forums, and the moderators I spoke to told me the threads where closed because of the designers attitude toward other SL members, and because of issues with selling a commercial product in the personal classifieds without proper authorization.

After repeatedly wanting to see test data the original poster resorted to more name calling , "I don't need to test it", "I work on heat exchangers", "I'm smarter than all of you", and "I just KNOW this works", "I don't need a wind tunnel, my foot is my wind tunnel", and of course, "I'M A SCIENTIST!!!!", and even went as far as manipulating a photo (wrongly, I might add) of airflow to make it look like his idea is pure science, which it isn't, it's a guess that could go terribly wrong, and actually his photo showed how proper laminar flow looks, without turbulance issues, which this mod could actually create. Sir, if you are truly a scientist, please do the proper testing in a scientific manner, not, "it doesn't smell anymore". My car had a smell in the first few thousand miles, then went away as well, that the smell went away on your car at the time of your mod is not a "scientific" determination.

I do not factually know 100% that this will cause problems, as I have not tested this mod myself, but many years of real world experience has shown that disrupting a laminar flow,especially to a cooling grid, can be very problematic. Again, I have not tested this mod, I do have the equipment, and have run data on a stock config and have found the flow to and through the radiator and engine compartment to be more than ample on the stock configuration, but I won't be cutting holes in my bumper to test this modification, especially since the "blocking design" of the bumper indicates through my measurements, that it does indeed direct flow in a laminar position, which is a good thing.

I would like to see flow tests done by the designer after his modification, but on the other forums, he refused to bother. Cutting a bigger hole is rarely a proper solution. The designer does not know flow dynamics to the necessary levels to make a modification such as this, and it is irresponsible to NOT properly test it when you are trying to get others to do it, and/or buy a product.

I simply want to let you know that, again, there is the POSSIBILITY of a very damaging airflow issue and I would hate to see others try an untested product based on this individuals word, and end up doing permanent damage to their vehicle, that certainly would not be covered under warranty due to this modification.

A few notes regarding THIS thread,
The moderators on SL "squashed" your threads because of your attitude, and unwillingness to listen to others, your knowing the workings of heat exchangers does not make you an expert in flow dynamics.

Dirt on the radiator is NOT by any means any indicator of airflow patterns, it is a strike zone of matter that is heavier than air. The lower half of the radiator is much closer to the road, causing a natural increase of road grime.

The holes in the upper grill are not vortex generators, nor do they act like vortex generators. Vortex generators are parallel airflow deflectors that create a flow vortex to increase drag or lift, depending on the application, on an airfoil. I have designed numerous vortex generators that are currently being used commercialy, privately and by the military, don't dig up phrases off the internet and throw them around like you know what you are talking about and to make yourself sound smart.

You have the POTENTIAL of 38.8 cubic feet hitting the radiator per second, not 38.8 cubic feet THROUGH the radiator.
Most current automotive radiators only allow ~40CFS maximum due to their cross sections, and this can not be increased without considerable compression that can not be achieved at velocities that a car is capable of, this being based on a 350 square inch radiator , any POTENTIAL increase over and above is nothing more than turbulence and drag, which is why you see so many cars on the road with rather small intake cross sections, modern vehicles are much more efficient in their cooling systems than even 10 years ago, and no longer need a massive multi-core radiator to keep them cool.

I have NO financial or personal reasons for this post, nothing at all to gain ,and no I am not a "hater", as was constantly being thrown around on that other forum. I am simply trying to let people know of the possible problems this COULD cause without being properly tested, and the onus is on the designer to be RESPONSIBLE and PROPERLY test this to be ABSOLUTELY certain that no harm will be done to other peoples cars.
I have said my piece and will not further respond to this thread, unless the original poster decides to do what a real scientist would do and run real tests with proper equipment and wishes to compare test data.

To the moderator I spoke to, I hope this falls within the realm of discovery and hope I have not been abusive in my attempt to clarify.

Thank you for your time.
Kiiski
 
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