BT Tech spoiler

Hello Bob and thank you for your comments below. The purpose of our spoiler is to disrupt or "spoil" the laminar flow going over the back of the car in order to reduce the amount of lift. Yes, there is drag but as you know this is the purpose of a "spoiler". The disruption of the air flow going over the car is what is reducing the amount of lift and creating down force which aids in the cars handling and stability at highway speeds.

I can tell you that there is a HUGE difference between driving the car with and without the spoiler. Unfortunately, Prius Chat suffered a server crash where there were a lot of posts regarding the handling differences our part made.

I am sure that those that have installed it will chime in here and give you their unbiased impressions.



Thanks!!

Brian
BT Tech
305-652-3115

 

I still think the best way to reduce lift is to put it on the hood, the front spoiler, or right at the beginning of the rear window on the roof (instead of the current tail end) where most hatchback spoilers are...

 

Do you mean something like this?
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It mounts onto the hood.

 

Heeyyy.. if it works.. Maybe it'll create enough of a wash to keep stuff off the hood or windshield too.

I was thinking, can't we confirm some of these spoiler ideas with just two cars, 3 people, vidcam and a bunch of string and tape?

Find a mostly empty stretch of road, have a lot of strings taped in a way to follow air flow, one driver drives the Prius, the other drives a car, and the passenger tapes.

 

My 2 cents.
If the BT Tech rear spoiler was further forward you would be disrupting more laminar flow and therefore you may add more drag (lower mileage). I think it is creating a new, higher pressure area in front of the spoiler (ala a Porche Boxster S rear spoiler) and turbulent flow over the stock spoiler(less lift).
Spoilers at the furthest point forward and aft on a vehicle have the most leverage/least drag effect (a smaller wing can be used for the same downforce if it is placed furnter from the wheels- this is why F1 and Indy cars have wings located furthest aft and forward).
The stock rear "spoiler" has very little extension past the back of the car so it's streamlining effect (straightening of turbulent flow behind the vehicle) is very little in relation to the rear width/height distances.

 

In the end analysis, every pound of downward force will cost you approximately a pound in drag force (assumption: spoiler at approximately 45 degrees to airflow).
Where you apply the downward force (front and/or rear) won't affect this but can make a difference in handling.
For example, if the rear of the car were subject to greater aerodynamic lifting, you'd want to concentrate your spoiler downward forces there. B)

 

Here’s my take on the effectiveness of the BT spoiler. I ordered both the spoiler & the chassis stiffening plate from BT Tech, of which the spoiler arrived about 3 days before the plate. I installed the spoiler as soon as it arrived & luckily had a few hour+ freeway drives to test it on. Then 3 days later I installed the plate & drove 3000 miles across the country & then back again a few weeks later. So I have a lot of drive time with both, of which a few of those days were with just the spoiler. In my estimation, based on those 3 days, sans plate, I would say the spoiler made the largest recognizable difference in helping out the handling on the freeway of the 2 devices. I just can't quantify what changes I have felt with the addition of the plate like I could when I drove the car once the spoiler was installed. That little piece has definitely made a difference to my experience.

Now this is all very unscientific because it's about different days with different weather patterns & wind speed/directions, etc. But I did drive many of the same freeway stretches with the stock Prius & now with the spoiler & it's quite noticeable how much it helped to make the driving experience more controllable at speeds above 70mph on the freeway.

The way I look at it is I just spent $23k on a car that basically handles like crap above 70mph on the freeway. However, I still love the car, so a small $200 investment for a potential handling improvement wasn’t even worth debating. The car is still not perfect even with these 2 items & I anxiously await further upgrades that could make the freeway driving experience a bit more predictable at all times. But until then, in my experience, this was an improvement that helps right now.

 

I'm doing the exact opposite.

I've already installed the stiffening plate and I've noticed an improvement. My car wasn't that bad to begin with, but it has improved the previous sway I used to get when taking the 270 degree on and off ramp turns in So. Cal.

I'll be installing the spoiler this weekend. I don't drive all that fast because I *like* high mpg. But I do get passed by the occasional truck, bus or whatever and I hope to feel a bit of difference there. I'll let you know.

I think for the small investment in a high quality product, any little improvement is worth it. Both the plate and the spoiler are crafted very, very well. And the support from Brian has been phenomenal. Fast replies to e-mail and even Wilma didn't slow him down too much. (That would be the hurricane....not his wife.)

 

I remember a while back (pre server crash?) someone installed the spoiler and had problems with it sticking completly. I have given up searching because the search engine won't except short words and gives me errors all the time.

I just installed mine last night. I followed the supplied instructions and applied pressure for at least 10 minutes. The edges had me worried so I looked at it about 10 minutes later and applied more pressure. I don't have clamps but the instructions didn't call for it. 8 hours later the ends are lifting and will not re-stick. The problem is that the spoiler is not curved but needs the adhesive to hold it to the curve of the window. I did make sure the glass was completely clean and paid extra attention to the last 5 inches on either side when applying the adhesive accelerator liqiud.

Has anyone who has installed this had a problem? How was it fixed? It's not going to fall off but isn't right.

 

Well your in luck, I'm the guy. I installed mine and went out and did the "after" part of my before/after mileage tests and everything stuck down just fine. A couple of days later we had some cold weather and 6 or 7 inches of each end popped up. Maybe due to the cold, maybe not. I tried to stick them down again just by pressing on them but they would pop up again in a few hours.

I went to Wal Mart and bought a tube of Locktite Stick'n Seal, it costs 3 or 4 bucks. I cleaned everything as well as I could and put the Stick'n Seal under the ends with a tooth pick as far as I could get it. I held it down on each end with a couple of small "C" clamps right around the edge of the hatchback. Turned the light off and put something in the opening to hold the hatch open. I just let it cure like that overnight and have had no problems since. If you get any of the Stick"n Seal on the window like I did don't worry it will scrape right off with a razor blade.

My mileage test is here: http://priuschat.com/spoiler-mileage-test-t11877.html

 

Thanks! I thought it was you or Godiva. I couldn't find the post. You might be right about the cold. At least I keep her in the garage and it's about 5 - 10 degrees warmer but it's still in the 50's early morning. I'll try the Locktite and get some clamps. I bet if I would have used clamps the first time it might have worked. The ends probably started coming loose within an hour.

 

With all new spoilers that we are currently shipping, we are including a small bottle of a product called 3m Primer 94. It is an adhesion promoter that you apply to the glass and let it dry for aprox 5-10 minutes. After it dries, you simply push down on the spoiler and you are done.

We also have a repair kit for those that are having an issue with the ends loosing adhesion with the glass. It consists of a small amount of 3m Primer 94 as well as a complete instruction sheet. The repair is very quick and simple and the hardest part is waiting for the primer to haze over.

If you have any questions please let me know.


Thanks!!

Brian
BT Tech
305-652-3115

 

I believe the product that you use is similar to what we are supplying with all of our new spoilers. We are now using an adhesion promoter called 3m Primer 94.

It gets applied to the rear window exactly where the spoiler will be attached. You basically "paint" it on with the supplied Q-tips and when it hazes over you simply push down on the spoiler at the ends and you are done.

If you would like me to send this to you please let me know.


Thanks!!

Brian
BT Tech
305-652-3115

 

Any chance of getting some of the new 2006 colors on the spoilers. I'd like to get one in the new Classic Silver.

 

This will be possible Doc but probably not for some time. You might want to look at getting a spoiler in either milenium silver or black as either color would be a good match for a silver Prius. If you are set in getting the exact match then I can check with the paint shop to see how long this would take to get.


Thanks!!

Brian
BT Tech
305-652-3115

 

Brian, I used Tumbleweed's fix with the Locktite Stick & Seal. I cleaned the ends the best I could with alcohol and clamped them down for 24 hours last Sunday. Today, I noticed they are lifting up again. The Locktite is stretching and light is showing through. I will post photos in a few days.

At this point it looks like I will have to scrape the whole thing off. Oh fun. One thing I noticed was that my spoiler might have too deep a groove where the strip of 3M tape is attached. I say this because even though I've applied plenty of pressure, some of the tape looked like it was clean (the back edge). Like it never touched the glass.

 

Did you ever receive our repair kit that fixes this issue?? The key is to use the 3m Primer 94 on the glass surface.

Let me know if you need a repair kit sent to you and we will take care of this right away.


Thanks!!

Brian
BT Tech
305-652-3115

 

Yes, that bottle was included and I used it. I spread it on with the Q-tips, paying extra attention to the last 5" on the ends like instructed. Waited 10 minutes for it to haze and applied the spoiler. Like I said in the last post, I think you put slight grooves in the underneath where the tape goes so that the spoiler sits more flush with the glass. It looks as though a good portion of the tape wasn't able to make contact with the glass in order to stick. It was hard to see but that's what it looked like. Is this possible? Like I said I can't think of anything else to do besides remove it and start over.

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