C. Beau

Does anyone have experince with the effect - or lack thereof - from cutting out the spare tire well?

I know its a fairly common modification but I've never done it on any of the few 951s I've had.

I'm currently building up a track tub and will for sure be taking it out for weight and accessibility if nothing else.

Does the rear valence really do anything? If it does I'd think for sure removing the well would do something...aside from save weight.

Anybody have any definitive lap time type of data?

LFA951

I just threw out my spare, never needed it, saved at least 20 lbs. there. The rear valance gives the car better aerodynamics, it's not just there for looks and the weight on it is minimal, it trajects air over the muffler and holds the rear end down at high speeds...

TheRealLefty

I've heard from various sources (none official or directly informed) that the Turbo rear valence is worth about 25 lbs of downforce at 85 mph, working as a classic diffuser, accelerating the previously tumbling air as it exits under the relatively high tail.

The diffuser is cut out to avoid the tire well. If you go to all the trouble to flatten the spare tire well bulkhead, it might make sense to add either a little aluminum or lexan sheet to fill in the diffuser cut out and potentially add a percent or two to its downforce effect. The front lower edge of the diffuser is knife edged a bit, no?

Kevin M

C.Beau,
One nice effect, is that you lose about 15lbs depending on what material you use to cover the newly created hole. If you are going to be running a proper wing on your track car, you won't miss it (rear valance). You will also like it for maintanence stuff e.g. accessing the transaxle, CV's, etc.

Skip Wolfe

You can always leave it in and relocate you battery to sit in it.

Mike B

Why would you want to cut out the spare tire well? So you can replace it with a similar piece? That makes no sense.

EDIT: I see you have made a less than positive impression resulting in a tme out. On a brighter note it will allow you more time with your reciprocating saw.

Guns951

+1 on the wing comment, if you have a wing forget the valance and just go with a diffuser if you must have something there. On the other hand, dumping the spare tire well and modding out the valance to look like the rest of it would be a great move. From the race shops i've talked with there is much front end lift with the valance as it not only acts like a diffuser but also like a spoiler for the airflow coming under the car - the flow is directed upward forcing the rear down. I've seen empirical data somewhere, but yes its true it yields much downforce at high speed and gives a more stable ride than one without.

chilibluepepper

Will this modification help make clutch changes simpler? It looks like it may allow enough rearward movement of the transaxle/torque tube for the shaft to clear the bellhousing, while leaving the engine in place. Is this the case, or just an optical illusion?

Chris White

BTW - the suports for the fuel tank (strap mounts) are attached to the spare tire enclosure...

95ONE

Man, I was just about to post that. I tried to weld that piece back in (Small cut out of original piece hanging down with the Strap hanger) to maintain it's use. But...... The darn sprayed on sound deadening from underneath kept catching on fire!! I had to machine screw it in with some angle iron for a quick fix. Sooooooooo. When cutting it out, please leave that strip there! It was good for right at 20lbs of steel removed. Damn good weight loss piece of you ask me. (Hard core Racer - not street)

And oh yeah. you can cut it out where you don't have to mess with the stock diffuser.

gcb951

This might sound dumb,
But, would decreasing the weight of the car in a place that is so far to one end effect the 50/50 balance that we all enjoy with our 944s. I know there are lots of things to do to reduce weight, and I am all for HP/Weight ratio. But could you negatively affect the 50/50 balance? I'm not a pro, so I don't know. Anyone, please chim in.