Anyone removed their hatch spoiler ?

[peanut]

I was following a nice early 944 Turbo home last night admiring a part of the car I don't normally see (the rear)
I suddenly thought that the rubber spoiler really dated an otherwise classic shape.
I really like the curvy chunky rear end of the Astons and wondered if the 944 would benefit from having the spoiler removed.
Has anyone done this job and has a picture ?
I don't like mods as a rule but I have Cup 1's which look magnificent and I suppose I could always put the spoiler back if I didn't like it.

What do you lot think about a 944 without the rubber rear hatch spoiler?

 

[A.Wang]

Does the rear spoiler actually contribute to aerodynamic down force, or is it just there because the 944 is a sports car? If it does serve a purpose (doubtful, it's rubber and it's not particularly big or angled), then it should be replaced rather than removed IMO...

I plan to replace the rubber spoiler on mine with some form of an adjustable rear wing, similar to one on the 968 Turbo S...or even something aftermarket that'd give me more down force once the rear of the car has been completely stripped out.

Nick - if you go down the "replace" rather than "simply remove" route, and you come across a nice adjustable spoiler/rear wing, I'd be keen to hear!

 

[Wigeon Incognito]

Early 924s have no rear spoiler at all so that would give you a rough idea of what it might look like. I'm not a fan myself although 924s looking a bit jacked up might have something to do with it.

Maybe somebody can find a better picture than this:

Edited to remove the embedded image, it was far too big so here's the link: http://upload.wikimedia.org/wikipedia/commons/e/ed/Porsche_924_rear_20071231.jpg

 

[Peter Empson]

It would definately be wise to go fit a 924 hatch if you go this route, removing the spoiler can be a pain as most of the fixings will probably have rusted and need to be drilled out. The frame will look unsightly unless you can find a way to cover up the mounting areas.

There's at least one car I've seen on Rennlist with this mod, it does look clean but it just looks like something is missing to me. I do quite like it with a proper race spiler mounted through the screen, but that's far from subtle. I'd rather have the six piece spoiler I have now or the huge Le Mans one (which probably dates the car even more as it's just a larger fibreglass version of the rubber one!).

The rear spoiler improves stability at motorway speeds, I ran without one for a few weeks and it is noticeable, especially in crosswinds. I can't remember if I ran on track without it now, it was a while ago. I wouldn't say it's dangerous, just not ideal and I suspect I'd have been a little hesitant to run at top speeds.

 

[peanut]

yes I hadn't thought about high speed stability in wind. I am sure Porsche didn't just stick it on for improving the looks of the car so I suppose it must do something.
The 968 is essentially the same car aerodynamically so I could always fit a spoiler from a 968 which does look more modern
I'll see if I can compare some pictures of all three options

Mmm it doesn't look too good on a 924 but then I don't like the 924 personally I think it looks like it has been squeezed .
From certain angles the back does look a lot cleaner but it sort of looks unfinished rather like the Cab does at the back. The cab boot looks like an afterthought to me

 

[DavidL]

When top gear bought an Esprit V8 for their 200mph attempt apart from fixing all the breakdowns they removed the rear spoiler saying it made no difference to the downforce and actually added drag even at those speeds.
Based on that I would suggest it makes no difference at all!

 

[944 man]

My car has a polycarbonate rear hatch and its currently fitted with a rubber 924 spoiler and it looks terrible: without a spoiler at all it will look worse.

 

[edh]

ORIGINAL: DavidL

When top gear bought an Esprit V8 for their 200mph attempt apart from fixing all the breakdowns they removed the rear spoiler saying it made no difference to the downforce and actually added drag even at those speeds.
Based on that I would suggest it makes no difference at all!

Won't you reduce drag by reducing downforce? - rear downforce might be less important for a straight line drag, but for handling, I'd leave it on. I'd expect there was a good reason why the 924 hatch gained a spoiler.

 

[Tam Lin]

ORIGINAL: edh

ORIGINAL: DavidL
Based on that I would suggest it makes no difference at all!

Won't you reduce drag by reducing downforce? - rear downforce might be less important for a straight line drag, but for handling, I'd leave it on. I'd expect there was a good reason why the 924 hatch gained a spoiler.

According to Porsche, the small lip rear spoiler reduced the Cd of the 924 from .35 to .33.

I think this is because there is no attempt at downforce, or really even reducing lift (unlike the 911 3.2, 924/944/968s never had the need of a frontal spoiler to compensate, implying no compensation is needed) but the point is to create a Kamm tail. My aerodynamic knowledge is relatively basic, but if I've got it right, the way the turbulence is managed behind the car using a Kamm tail increases stability (this worked for the 917KH just dandy), and reduces drag. Wings, like the ineffective Lotus effort, and the 968 type, seem marketing, not aero devices. The 1980/81 LeMans 924 GTPs had a deeper, lipped, fibreglass version of the 944 spoiler. I don't think this was meant to make them look pretty.

 

[DavidL]

I think Tam Lin's last sentence may be the crux of the matter. Spoilers designed to function rarely look good but serve a very valid purpose on a racing car. Put these on a road car and noone would buy it so they get diluted a little!
Remember the 2 tier things on F1 - one about 6 feet off the ground.
Having said that the Rs500 sierra had another little spoiler the standard cossie didn't. Either they wanted to add a visual difference between the models or they thought it did something useful?

 

[peanut]

there is another possibility . The spoiler may create or break turbulence at the back of the car and shift the exhaust gases away from the rear hatch area . At motorway speeds I doubt if it has much effect on downforce to be honest. The turbo spoiler on the S2 and Turbo would have a much greater effect by reducing airflow under the car and thus creating suction

 

[Fen]

Years ago my neighbour broke my bridge spoiler off when trying to set the alarm off when he'd been on the pop. I'd say it made not one iota of difference to the feel of the car when I ran it for several weeks with no spoiler.

Now my experience is at odds with Peter's so I'd suggest the difference is probably the presence of the rear under bumper section on my car; something the cab also has incidentally. On the other hand the 968 does not have any visible form of lower aerodynamics yet shared the bridge spoiler of the later 944, so maybe none of it does anything. That leaves me confused however as Peter's is an opinion I trust and he noticed a difference. Does the 968 have some undertray shaping to replace the more powerful 944's rear under-bumper contraption's effect?

I believe that the 968 Turbo S rear wing should only be used with a front lip to balance it out, much like the impact bumper 911s needed the front rubber lip to balance the whale-tail. I haven't tried it without the front splitter on mine to confirm, but I know that my completely unspoilered 911's top speed was limited by the lightness of the front end rather than any inability to accelerate.

 

[pylonracer]

The 944 spoiler definately has a positive effect on the cars handleing at speed, whilst it may not produce much or any downforce it will be killing LIFT.

The rear spoiler will work in conjunction with the front spoiler to balence the car, if you take the rear spoiler off you not only loose the effect of the spoiler but you also have the front spoiler trying to lift the backend of the car by pivoting on the front axle line. This will not show up much in a straight line but will be noticeable in sweeping curves

Smaller rear spoilers like the following types Audi TT (just cast your minds back to that saga) ,Ford Ka and Porsche 924 to name a few decrease lift at speed but are probably not powerful enougth to have to be considered as a package with a front spoiler.

I made the spoilers for the 1999 Ford Focus WRC car and was told at the time that the little bib spoiler on the Ford Ka hatch took 150kg of lift away from that car, the stylists did not want the bib, the engineers said you will kill people without it !, on that occasion the engineers won.

The 944 spoiler seems to make muck stick to the back of the car and also be very careful driving a 944 with the boot slightly open (like carrying some thing sticking out of the boot) the exhaust fumes come back into the car very badly.

Just my thoughts and experience.

Baz

 

[Peter Empson]

ORIGINAL: Fen

Now my experience is at odds with Peter's so I'd suggest the difference is probably the presence of the rear under bumper section on my car; something the cab also has incidentally.

I've now had a look back through my Titanic posts as this was about 7 years ago (my memory is shockingly bad, so I like to write things down wherever possible, that also explains at least 50% of the drivel I write here []) and it appears I definately found it to be an noticeable, I didn't appear to do any trackdays without it so this was based upon road useage.

There may be other variables at play here however. As you suggest, the under spoiler could have been an issue, I had the parachute of a toast rack at the back of the car which I can only imagine adds a lot of drag (and god knows what else).

This was also just before I changed to Cup 1's, so I was running the same sized (215 I'd guess) tyres front and rear. I imagine you would have been running wider tyres at the rear than me which may have masked the difference. I know my original suspension was nicely worn in too (or shagged to put it more succinctly[]) which could have allowed more movement.

I felt that the 968 Turbo S spoiler improved downforce over the rubber spoiler, however I cannot say I've noticed a major difference changing the angle of the adjustable one on the car, but it runs in the steepest settng now to avoid it becoming a pond when it rains []. I have toyed with the idea of a gurney type flap on its rear edge, but I think I'll worry about aerodynamics sometime next year when the next round of mods are planned and take some specialist advice from a neighbour that lectures on race car design (who incidentally is in his 80's and still very quick on hill climbs, I wish I had a fraction of his skill).

Sorry, gone waaaay OT again []

>Edited to add it appears you can't write 'sha99ed' here

 

[SteveSJS]

I had at one time an early dog leg 924 without spoiler.

Feeling brave I decided to try out a little of it's top end - I can only say that even in a straight line at barely into 3 figures is felt so 'nervous' I ran out of bottle and backed off.

I was doing some refurbishment of the car and decided to replace the rear hatch as it was not in good condition and very few of the de-mist elements were either connected or working. The replacement at the time came from Porsch-apart and was complete with spoiler.
Soo - you can see where this going - a little while later - I had 125 indicated with a car that was rock-steady and felt very comfortable at that speed.

Not at all scientific I know, but my 2 c for what it's worth.