rayfinkel

I was curious if anyone had any ideas on how to lose unnessary weight on the 928. I have no desire in keeping the car stock. I just want to keep it street legal, "practical" everyday sports car driver and asthetically pleasing.

Two things I have done are:
1. removed the headlight washer "unnessary".
2. removed the heavy cleaner unit for the windshield also unnessary.

Things I am contemplating:
1. removing the battery tray from the rear and monting a lighter weight battery in the front.
2. redesigning the fuel cell once the battery tray is removed to an alluminum cell that is closer to the center of the CG.
3. removing the headlight assy. and installing somthing of my own design I was thinking of tring to use the new corvette headlight assys and modifing the quarter panels to suite. It would also help with Cd. but cost is a factor as the corvette assys are roughly $500.00 on ebay a piece.
4. using a retrofit kit and putting a corvette engine in the car. not only saving on weight but also increasing horsepower and cheaper to maintain. the only thing is the enitial cost of the conversion.
5. removing the sunroof and welding a thin sheet in its place. I am asuming the glass and motor is heavier than the sheet of metal.

I would really like to bring the car down to 2500 to 2800 lbs. and I think I will have to come up with alot more to reach that goal if its possible.

also to note that I want to keep the proper cg or at least not throw it completely out of wack.

89 S4 5 speed
also 77 euro5 speed

djurek

Here are some tips. Are you trying to lighten the 77?

https://rennlist.com/forums/showthre...ferrerid=51576

doktor-t

I can understand tossing the headlights for some Corvette units but the engine, I´m not to sure about that.

Don´t relocate the battery because it suppose to be placed at the rear for weight distribution resons. The fueltank I´d leave in its place too.

Be aware that shedding pounds at the rear will get you worse traction!

Remove the stereo, cruisecontrol, powerseats, air-pump, get lighter horns, build a new lighter exhaust system, swap the outside rear view mirrors for some GTS units (plastic) and would have saved a good amount of weight.

Remove AC-compressor maybe?


/Tobias, Sweden

The_Remora

Instead of hacking up a 928 and morphing it into a Corvette, just buy a Vett.

Or if you want more power just buy a supercharger kit. The track guys here have a lot of good threads on weight savings that won't ruin the car's handling.

FlyingDog

You're trying to move weight rearward, not forward and down, not up.
The fuel tank is offset to conpensate for the driver.
Unless you really like the look, it's a waste of money. Look into Strosek/Jacquemond or Porken's headlights.
You can build a 928 stroker motor with huge power for what the bastard conversion will cost you with a decent motor. If you are planning on racing, many classes (even fairly unlimited classes) are banning engine conversions outside of maker or even model.
The sunroof is metal. Are you sure you have a 928? This is the only worthwhile weight savings idea in your list although a lexan/plexiglass/kevlar/carbonfiber panel will cost less with less work and accomplish the same thing.

Swapping seats (40-60lbs each vs 12-25lbs for racing seats), removing A/C (~75lbs), and asphalt floor insulation (~75lbs) will do more towards your goal than anything above. Several 928 racecars are in the 2600-2800lb range.

rayfinkel

Thanks Dan Jurek for sending me to that previous link. That pretty much answered all my questions.
and yes it is the 77 that I am trying to lighten.


Now I am curious if there has been better results with distributing the weight more to the rear or keeping the cg the way porsche designed it is the best idea?

89 S4 5 speed
also 77 euro5 speed

FlyingDog

It's easier to drop weight from the rear. If you can shift any weight from the front (that must stay in the car) to the rear, you'll stay closer to the way Porsche designed it. If you go below 3000 or 2900, the balance will start going forward quickly.

BC

As was mentioned, leave the batter back there. You can remove the non-frame area in the rear, and then add weight back there, taking it off the front, by putting things like an electric PS pump back there. Technically the extra lines add weight though.

Get rid of the huge reservior in the passenger front fender, cruise in the drivers front fender *behind the wheels*.

That thread has good stuff for total weight savings, but don't forget the distribution, front and rear contributes to how the car feels.

I am removing weight, but adding some back for various reasons, and hoping to have a net loss, with a distribution change towards the rear. I like the lighter turn in feel of mid engined cars. With 600 pounds over the front axle I won't be able to change that dynamic, but slight changes can add up.

James-man

Rear weight does matter. I swear I can tell the difference when I forget to remove the hidden tool kit from the back. I want to say I am faster with it in.

The weight savings link is good. If it was me considering a similar list as you compiled, I would probably simply choose to buy a good used Corvette.

mark kibort

Guys, the 928 is very balanced to begin with. As was said, as you lighten the 928 up, most of the weight comes out of the rear. You end up with a car that is 55 /45 % which, is not that bad. Certainly, you are not going to feel ANY real difference with a 100lbs here or there, even at the track. I can remember many races where my best laps are the 2nd laps with a full tank. AND i can remember, the last laps being just as fast. 1:39s at Laguna for example. There are far many other handling factors that you can address besides pefect balance or cornerweighting. one of the key factors is cross weights. keeping that under 10lbs or so helps with handling.

If you want to drop weight, you certainly dont want to move any weight from rear to front. replacing bumpers with smaller versions, or removed all together, lighter weight battery like a 14lb Oddessy, removal of the headlight assembly, lexan windows, lightweight seats, remove insulation and then replace the carpet if you are still wanting a street look, lighweight starter, wheels, muffler system, and thats about it. You certainly are not going to get a 928 as light as you are talking about (ie 2800lbs) unless you are really going to race it out. Lets face it folks, the 928 is not a real light car, however it can be made pretty light for racing, comared to the HP it can produce.
forget about the engine transplants with chevy. A 928 stroker can be made pretty cheaply, (relatively speaking, for its hp made) and I dont think its worth the effort to save the 50 to 100lbs or so for the Chevy v8

MK

largecar379

1. use a lighter battery, but do not relocate to front
2. do not relocate fuel tank (cell) as it offsets the driver's weight (left to right)
3. what difference does the drag coefficient make while driving at night? putting in flush headlights is one thing......
4. see below----(what's wrong with your motor?)

Renegade conversion starts @ $1500 for the basics (manual trans).

Add Chebbie engine (450 hp Edelbrock crate motor--$8K + [Summit Racing]), clutch can and related--$700, headers--$900, accessories (????), flywheel/clutch--$425, etc.....

Over $3500 plus the Chebbie (????), just to get started......

build your engine:

4.5L Euro high compression piston/ring set--$500 (I have a set NIB)

set of bearings--rods/mains, less than $500

rebuild/mod heads--$1600 (ported/polished, 5 angle valve job, unshroud the valve pockets, port match in/ex, mill heads)--just had mine done

TB/h20 kit--$700 (928 GT)

Gasket kit--$350

headers--$800 (MSDS coated)

custom cams--$800

service/mod your K-jet system--less than a grand

$6250 and you don't have to fabricate or change anything........and you can get near 400 hp from a 16V----need more? just add a blower

just over $6K versus near $12K.....you decide.

5. replace sunroof (and related parts) with Lexan.

follow the links to weight removal for starters. then think seriously about engine conversions and such.....they do make a 928 different, but weigh the costs before stepping off into something you may live to regret.

the numbers above are not actual, but within range when rebuilding or doing the conversion. your actual costs will vary depending upon how deep you get into it.

Good Luck!!!

--Russ

rayfinkel

Wow,
I have to say you all gave me alot of good info! and now the brain is workin!


I was wondering if anyone has had good results with putting an electric PS pump in the back and if so where did they put it and what pump did they use.

89 S4 5 speed
77 euro5 speed

BC

The Toyota MR2 pump from the 90s seems to work well and is not too heavy.