When you pull out the stereo, I would be interested in the antenna booster.

Bryan
86 951

 

Ok, started with the doors yesterday. This is one of the heavyest factory components on the car. Removed the entire door panel, window assembly, motors, arms and proceeded to cut out all the sheet metal to about a 1" perimeter all around. Cut off all the brackets and clips. Removed all the weatherstriping and door moldings.

I left in place the steel door impact brace (I have a X-type weld-in cage for side impacts) and ground down everything smooth. Plan to repaint what's left of the door interior and fabricate a bracket to remount the interior door latch.

The interior rubber door molding works perfectly to finish off the "rough" cut sheet metal and the whole door interior looks really clean. Haven't weighed the stuff yet but it feels like about 30 lbs lighter. Multiply that by two doors and...

Stereo is gone too. Have to start cutting out the MDF speaker box that is fiberglassed in where the rear seats used to be. Still not comfortable removing all the heater and A/C stuff under the dash. I just don't know where to start!

Rear bumper is going tomorrow. Lexan hatch is coming soon. Just have to rob another bank first!

 

I'm not sure on the math, but it seems to me those numbers are low.

For instance, I've got a stock 944 na. We'll assume your numbers, 2600lbs with 120 HP. So removing 20lbs will add 1 HP. I'm assuming the opposite is true. Adding 20lbs will remove 1 HP. So me weighing 250lbs gets in the car and now the HP is reduced by 12.5. Then my friend who's also 250lbs gets in the car and now we're down 25 HP. Bringing the total to 95 HP. It seems like that's a rather large change in HP for just adding people.

I will say that I do notice a difference with another person in the car, but I really can't tell if the difference in 12.5 HP. Maybe i could do some quarter mile runs with the G-tech and see if the difference is that great.

Note: Not a flame, just a question.

 

I would say that your math is right. If you increase the weight by ~20% (adding 500lb to a 2600lb car)you will require 20% more force to accelerate the car at the same rate as if it were empty.

Keep in mind the the force we are talking about is torque, not HP. HP is what describes the continuous work required to move through the air, overcome frictional losses, etc. Torque is the force that creates the acceleration. HP is torque(or force) per unit of time.


Art

 

[quote]Originally posted by kellyk:
<strong>Rear bumper is going tomorrow. Lexan hatch is coming soon. Just have to rob another bank first!</strong><hr></blockquote>

As for the hatch, to save some $$$. How about some plexiglass rather than lexan?

easy to bend, cut and it is lightweight. Or are there regulations preventing plexi?

 

Kelly-
I'm up in tustin.. I've got a lightweight Glass from an S.. not the 83 pound weight saving but could be a upgrade thing is going to the wrecking yard this week email me at matt@segcomputers.com if you want it.. the frame is tweekd but the glass is great..

Matt

 

[QUOTE]Originally posted by JohnK944: "As for the hatch, to save some $$$. How about some plexiglass rather than lexan? Easy to bend, cut and it is lightweight. Or are there regulations preventing plexi?"
__________________________________________________

Most sanctioned clubs won't allow plexiglass for windshields or rear hatches. I'm not sure why? I think I could use it for my two side rear windows but those aren't too expensive to get in Lexan. The rear hatch is a big ticket, about $800 from GT-Racing.

 

[quote] lordgrommit
Kelly-
I'm up in tustin.. I've got a lightweight Glass from an S.. not the 83 pound weight saving but could be a upgrade thing <hr></blockquote>

WHAT DAT MEANS?
Please explain - lightweight glass, and S, ?

 

I was thinking the same thing. What is "lightweight glass" and how much less does it weigh than normal glass?

 

[quote] ...won't allow plexiglass for windshields or rear hatches. I'm not sure why... <hr></blockquote>Simple: plexiglass will scatter when some stress is put on it.
The fragments will be as sharp as razor blades.
Front shield is to remain glass.

Side windows can be cut from a plain sheet using an jig-saw. If you get material of the same thickness as the glass, you can use the OEM rubber to install, safes you fixing some sort of clamp.
An other nice one is the rear hatch un-locking mechanism, would safe some weight there as well.
[quote]It would make a difference in handling to remove ...weight from .... <hr></blockquote>To re-balance: move the battery to the back, spare wheel well would be nice.
Get the clamps from an junk-jard, Golf fixings will hold the battery as well.
Cabling can be welding cable, the thicker, the better.
TakeCare

 

"Using Art's formula, Force is increased by 16% or the equivalent of 84 HP (16% of 525HP). To arrive at the HP equivalent per pound, divide 454 (total reduced weight) by 84 (HP equivalent). That equates to 1 HP equivalent for each 5.4 pounds of mass removed. "

Hmmm, power is force per unit distance per unit time... Can't quite plug HP into F=MA anyway...

Well, I've never really like the the lb/HP rating anyway because of several reasons. First, that peak-HP number you get occurs but at a single RPM. Unless you've got a CVT, your RPMs will change as you drive the car, rendering that rating useless. Unless you compute lb/HP for every data-point on your HP graph vs. the RPMs you're using.

Second, it's torque, not HP that determines your acceleration. Take torque, multiply it through your gearing, divide out the radius of your tire and you'll have a linear thrust force F at the ground. Plug that into F=MA, A=F/M with your car's mass to figure out what your resultant acceleration would be.

Case in point: compute the lb/HP ratings of a Ferrari Testarossa vs. the Ferrari 288GTO, then compare to their 0-60, 1/4-mile, top-speed times and see what correlation you get.

 

[QUOTE]Originally posted by Danno: "Second, it's torque, not HP that determines your acceleration. Take torque, multiply it through your gearing, divide out the radius of your tire and you'll have a linear thrust force F at the ground. Plug that into F=MA, A=F/M with your car's mass to figure out what your resultant acceleration would be."

__________________________________________________

OK, here's the deal without the physics. Take weight out go fast faster. Thats an equation that seems to always work. Don't ask me why or how, I'm only the driver!

 

Yup, simple enough. Less weight = faster car.

 

Hey KellyK,

Yep, it is truly fun to pull all that stuff out and see the weight savings. Did the same thing with a 1st-gen RX-7 back in about '95.

You know, the full-boat power seats in a 951 weigh about 50 lb. per, and a good Sparco fixed-back seat weighs 15 lb. (or about 11 for the carbon-fiber version), so there's an easy 70-lb. reduction right there. BTW, where'd you get the fiberglass sunroof panel?

Happy removing!

 

[quote]Originally posted by Doug944s2:
"Hey KellyK, You know, the full-boat power seats in a 951 weigh about 50 lb. per, and a good Sparco fixed-back seat weighs 15 lb. (or about 11 for the carbon-fiber version), so there's an easy 70-lb. reduction right there. BTW, where'd you get the fiberglass sunroof panel?"

The factory seats are long gone. I tried to find an old 924 roof panel from a wreck but they are hard to find. Ended up with a GT-Racing fiberglass unit. With a little work I got the original rain gutter moldings back on the the top looks like it is original (except no sunroof).

Just weighed all the #$(^ I took of the car today and it totaled out at 193lbs. Still have more to go!


Happy removing![/QB]<hr></blockquote>