OEM seats and 3 point vs roll bar and harness

I am currently building a time trial car and am pretty torn about what would be best to do for safety. The car is a 2012 BMW 128i so its has pretty up to date factory safety (side airbags, seat airbags, not really a tin can) so my question is would it be safer to keep everything oem (with the addition of a 3 point hans hybrid s) or add a roll bar, halo seat, and 6 point harness?

I have no plans to W2W and I imagine rollover is low risk in TT so for a front and side crash would I be better off keeping everything oem since it was designed for these kind of crashes?

I'm not sure about what's actually safer, but the bar/harness/seat combo has to be better for controling the car vs. sliding around on OEM seats like I've been doing for 2 years.

red_stapler said:

I'm not sure about what's actually safer, but the bar/harness/seat combo has to be better for controling the car vs. sliding around on OEM seats like I've been doing for 2 years.

That is part of the reason. There is definitely weight to be lost and timed to be gained going to a fixed seat but im also trying to come home in 1 piece!

Is the car going to be street driven? If it is you need to retain the three point harness.

If it's a track only car then the better route is bar/cage, seat and 6 point belt.

Assuming the car is being street driven.

Are you ultra serious about time trials?

Will drive the car at the absolute limit despite the the risk?

If you've answered yes to either one of those than you need to rethink a dual purpose car.

If the car is being trailered

Don't bother with half measures, put all the gear in the car.

In summation

I don't have issue with either route but if you are keeping it more street car than you need to be cognizant of the fact that you need to leave yourself more margin on track. I drive my formula car in a much different manner than when racing the Datsun, there are no small crashes in the formula car so one has to drive accordingly. 

Tom1200 said:

Is the car going to be street driven? If it is you need to retain the three point harness.

If it's a track only car then the better route is bar/cage, seat and 6 point belt.

Assuming the car is being street driven.

Are you ultra serious you about time trials?

Will drive the car at the absolute limit despite the the risk?

If you've answered yes to either one of those than you need to rethink a dual purpose car.

If the car is being trailered

Don't bother with half measures, put all the gear in the car.

I don't have issue with either route but if you are keeping it more street car than you need to be cognizant of the fact that you need to leave yourself more margin on track. I drive my formula car in a much different manner than when racing the Datsun, there are no small crashes in the formula car so one has to drive accordingly. 

 

 

I should have put this in my original post. The car is only street driven to and from the track. I agree a cage is the way to go but I currently am not towing as I dont really have the room for a trailer and the only car that I owne that can tow is also my wifes DD. I guess thats why its an odd question. The car is not a dual purposed car but since I cant trailer it so a full cage is kind of out of the question for now.

In reply to gr4v3r :

Not an odd question at all. There are a lot of people doing exactly this for the exact reasons you are. 

There are fixed back seats that will still work with a 3 point harness. For the track I'd prefer a fixed seat (with the back braced to the roll bar) competition roll bar, 6 point harness and head & neck restraint. For the drive home you need the 3 point harness unless you plan to wear the helmet and neck restraint on the drive home.

Your statement about getting home in one piece is a good one......that's the number one goal for all of us.

gr4v3r said:

 I imagine rollover is low risk in TT 

Not a good assumption

If you don't need the back seat and don't mind the damage installing a rollbar will do to the car, the clear choice is a rollbar, fixed back seats and 6 point harness.  Retain the 3 point belts for street use.

The engineer that designed the Hybrid S has said that after all Is said and done, he tracks his mustang with a 3 point and hybrid S. 
 

If you do HPDE at 11/10ths like a lot of people do, I don't see how TT is much different 

But, as everyone else said there aren't any half measures. Once you have bars by your head you shouldn't ever drive it without a helmet. 

If you're driving TT competitively, the only real difference from W2W is the likelihood/number of other cars in proximity.  You still have the potential to lose control and go off track, or impact something hard.  If you go off track, there is always the possibility of a rollover.  Modern factory safety systems are very good at protecting us at street speeds, but I worry about their effectiveness at racing speeds.

The other benefit of a full racing setup is car control.

If the car is nearly a full time track car as it is, I would go the next step... bar, harness, seat and HNRS.  

I personally won't run 10/10ths in anything that isn't fully caged.

If I were doing TTs without all the goodies I'd notch it back to around 98% on the sections of track with less room for error.

Thanks for all these comments, they are super helpful. Im still slightly torn but I am leaning towards seats and a roll bar as it seems like its slightly a wash, possibly more safe, but also would be a performance gain.