Help, get rid of side drafting, ideas?
 

Hi, used to race my car, the car used to have a monstrous engine, but i detuned it! Now i'm a pray not a hunter.
Today, i was racing at the track and experienced a new thing for me, because my car is now way slower, some guys can run head to head with me, i was racing my golf mk4 tdi in the final lap, and then, a toyota celica 2.0 was pulling side by side with me and my car breaks a lot twice when he was able to put his front wheel in my rear wheel!!!
At first i didnt understand was happening because i used to race with a very beefy version of my car and no one ever pulled by my side, head to head, i was thinking that was my engine breaking or something like that because i was at the limit for a very long time!!! but then i realized that was side drafting(a new thing for me lol).
Does everybody know ideas to get rid of this??? Next week i will race again and i know that celica 2.0 guy will be there to try to kill me because i really humiliated with my diesel crap car.lol

By the way, i have to sets of wheels, the ones i run today was flat, very closed, no air gaps, i have another set, 5 spoke, very wide gaps between the spokes, i dont know if i use the open ones will avoid this, because this is my first time with a detuned engine and using this set of wheels, i never feel that before, this was my first time in about 6 years of racing.lol
I used to run a diesel with a monster torque and about 300hp, now i'm almoust stock and my only way to run against other machines is to have perfect tyres, gearbos, suspension, aero, weight, etc, my engine is very weak now so i need to have everything else at top performance.

Why would you de-tune a race car? Race cars are supposed to be fast and fun.
Get another car if you need efficiency and don't race it- mod-it for economy.

I have no idea. In fact, I'm not even sure what you're asking; let alone why you'd want to get rid of it.

Side drafting—it sounds like suction holds the cars together so the faster one pulls the slower one along? It doesn't work like that.

Try trading paint.

I detuned it because i want it road legal again.
Well, to make you understand what i felt, i was at 215kmh(about 133mph), and the celica was drafting in my tail(all ok), but then he was able to go by my side, i feel like my engine breaks hard, but in fact it was the celica causing very hard drag in my car.
http://3.bp.blogspot.com/_iEozCoYD5n...ing+passed.jpg
I wonder if it possible to do something to avoid this(i know, i can shake my car and get rid of others, but it may be dangerous sometimes), i like to do clean passes not wrecks.

What I am thinking happened is that when the Celica pulled out to pass you you lost the benefit of him drafting you. Here in America on the big race tracks NASCAR drivers pair up and and run bumper to bumper so that each car is only dealing 1/2 the drag (1 moving the air, the other dealing with the rear drag). I think what happened to you is that as the Celica was gaining on you, it started to break the drag pulling at the back of the car and enabled you to speed up a little. When he pulled next to you, all the drag came back, loaded the engine and enabled him to pass.

Some type of kammback or boat tail might help with that but not sure what would hold up at 133mph...

What Mike says makes sense. You benefited from the Celica when he was "drafting in your tail" but then lost the benefit when he pulled out and went by your side.

What aero mods are allowed for the racing?

Not really, i know for sure that was the celica causing drag in my car(what i dont know is what in fact cause this), because the car really breaks hard twice when his wheel was by my wheel, it's very common i heard a lot street racing people talk about that but never experience this, you loose a very good amount of acceleration when this happen, it's like your driving a truck for seconds, and then when i leave celica way behind everything is normal again, i pulled whit the celica side by side but whit big space between us and i smoke it, he doesent have a chance, he only had a chance drafting and when this happen because my car loose a lot of speed, it's like you hit the braking pedal hard, scary at 133mph, he also recognize that this was happening.
Remember, i drive a street car, golf mk4, not a good nascar car with good aero tested in wind tunnel and builth for race.

I think part of my question is answered here:

https://www.youtube.com/watch?v=VA-5Oe2bYPc

but i think there is much more because celica didnt pass me, and one this this happened he wasnt drafting at my rear, it only happened becase his wheel is almost touching my wheel.

I also find very good info here:
Ten80 Student Racing Challenge

side drafting
 

As he moves from behind,you lose the benefit of the 2-car draft
http://i1271.photobucket.com/albums/...ead2/Gaps2.jpg

Why when you can have both in the same car?

Thanks to modern tuning it is possible.

Thanks aerohead, i think you are all sure, but i was shoking because it never happened to me before, nobody ever raced head to head whit me, so, i'm like 30years old drafting virgin, everything is new to me.lol
I think most of you guys never feel this, believe me, it's scary, it's like you hit your brakes very hard or an anchor.lol
So, there's no way to avoid this, the only way is to block the passes for everycar.

EDIT: aerohead already posted even better information about nose-to-tail drafting! :)

OK. Then I would be interested to understand the physics behind the "side drafting". When the physics is understood, then the solution to prevent it could be found.

I believe the nose-to-tail drafting advantage is well proven; a good discussion is here: HowStuffWorks "How NASCAR Drafting Works". While the article covers NASCAR, the drafting advantage to the front vehicle is not limited to NASCAR.

So it seems clear from what is known that you will notice a sudden increase in drag when a car which is drafting you pulls out from behind you and tries to go next to you... especially at 215km/h.

But it is not clear what is happening when the car is coming next to your rear wheel. What might be happening, if the other car is very close, is that it is disrupting the smooth flow of air along the side of your car, creating even more drag than normal. Maybe this is your 2nd noticeable increase in drag (it is not the engine braking hard, but the aero drag increasing which means more engine power is needed to keep the current speed)

Not possible with my country laws, believe me, my car has 115hp stock, and it's diesel, with diesel comes noise and smoke, i hate noise and smoke on streets, not fair with other people, they dont need my smoke and noise.
https://www.youtube.com/watch?v=WtZ5dYLvyd4
My engine was tuned like the one in the video, the sound was the same, the smoke was the same.

This quote from the Ten80 site seems to align with your description very well:

That is why I asked about what aero modifications you are allowed to make on the car when at the race track. If you are allowed to add something like a Kamm-back on your car, then you might be able to reduce the effect of the sudden drag when a car moves out from behind you and goes next to you. Of course, the Kamm-back will help you around the entire track. And it could be removable if it is not allowed to have these kinds of attachments for driving legally on the road.

This may not apply, but I've noticed when a semi truck passes me, there is a time about when his front end pulls even with my back end when it feels like he's sucking me backwards. I don't know why this would be, unless the increased velocity of the air moving around him causes a corresponding low pressure area around it. Then when that low pressure area is directly behind me, it causes the increase in drag. ???

Of course, this quickly transitions to a feeling of a crosswind when he's about halfway up my car length. I attribute that to the air he's pushing aside hitting me in the side. Then of course, once his front is cleanly in front of me, that sensation goes away...

I wonder if that's the same thing that happens when you're racing???

In road, at my country, it's not allowed any kind of modifications, if the cops know that you have mods, you gonna have problems for sure...
In track i can do what i want, i can do a kamm-back, but i want to go for a most discrete as possible way, something that other drivers dont care about.