Targa aerodynamics top on vs top off

[safe]

I was out riding in the sunshine yesterday with the top off, quite fast.

Is it my imagination that the car is more stable at high speeds (80-100 mph) with the top off?
It also seamed to have a higher drag because the top speed was slightly lower.
Itīs the second time I notice this (I usually donīt drive so fast... with the top off that is ).

My car has no wing but a front spoiler.

[Bill Verburg]

I have never seen hard #s for a 911 targa but I have them for a 914, the following are C_D #s roadmeasure/windtunnel % inc over base(only for windtunnel #s)[list=1][*]lamps closed,widows closed, roof on 0.360/0.363 [*]like 1 but lamps open 0.387/0.380 +5%[*]like 1 but side windows open *****/0.381 +5%[*]like 1 but roof off ****/0.389+7%[*]like 4 but side windows open *****/0.447 +23%[*]like 5 but w/ lamps open 0.535/0.464 +28%[*]like 2 but side windows open 0.419/*****[/list=1]

the road #s are higher than the windtunnel #s because of sidewall effects in the windtunnel

[safe]

Itīs the expected thing I guess, higher Cd with top off.

It would be interesting to see if lift numbers go down with the the top off. The car not being the perfect wing profile anymore

[Bill Verburg]

It would be interesting to see if lift numbers go down with the the top off

My pure WAG is that w/ the top off there is soooooo much dirty air, that lift goes down a lot.

I see it happening w/ sails all the time.

[kach22i]

Originally posted by safe
Is it my imagination that the car is more stable at high speeds (80-100 mph) with the top off?

Have you tried top speed both ways?

I once did top off windows rolled up - 138 mph, think it peaked at 140 mph, was too focused to look down one last time before letting off the gas as traffic came up real fast.

A crazy thing I will never do again, had to try it at least once though.

1977 Targa 2.7 CIS.

[safe]

Originally posted by kach22i
Have you tried top speed both ways?

Nope, must try that!
If I die, I blame you

[AFCuk]

Hello

Tried that too with the top on.
141mph lots of wind noise.
top off about 120mph think its the air rushing round your ear holes that dose it.
4 up too lil scary on the swooping bends tho

[john walker's workshop]

rumour has it that engine cooling air intake is reduced with the top off, due to how the air flows over the rear of the car, and the engine can run hotter. anyone ever notice this?