77tony

Pretty cool, you can predetermine your gear by hitting the paddle up or down, once, twice, etc. Problem is the paddle manual cost is high $2400 per copy. T

Aspkiller

In the world of sequential paddle shifters, $2,400 is pretty cheap. Trouble with Master shift is that you have to hit a clutch button AND it will ultimately be slower than a competent driver in a race car AND you have no control over how it clutches/shifts, as it is an open loop system. It also isn't really designed for flat shifting. A true sequential paddle is much more expensive and you don't use the clutch, except for coming out of a dead stop and the shifts are controlled thru the ECU or GCU for delay, cut and ramp decay. Check out the Geartronics UK website for a better understanding of aftermarket closed loop systems. A flat shift paddle system, as offered thru SpeedSouth, is using a Lingenfelter ignition cut box with a factory ECU. It isn't ideal, but it works. Their upcomming modifications will be using MoTec ECUs (about $12k each) with their paddle set up.

We recently worked with the FAST XFI engineers to see if we could get a mod to their ECUs and have been promised a flat shift engine cut input section that will be much more affordable that the MoTec.

As to my setup, all work is only done at the shop in Carson City, NV and we don't intend to build a kit.

mark kibort

you get paddles or sequential shift lever, that is actuated by this system as soon as you push the clutch in. you regulate the release of the clutch, normally, so its a pretty cool system. But, it would be wierd to shift and then wait for it to shift until the pedal was pressed and released. seems kind of odd. maybe you can operate it by normal methods, by puting the clutch in and then hitting the paddle to change gears.

very cool

xschop

Asp, did you weigh your car?

Aspkiller

Currently we are pretty heavy at 3,045# with me and 8 gallons (200#). A couple of offsetting weight issues are a fairly heavy front splitter frame that has an adjustable stabilizer going to the front of the lower control arm area, 16 quart dry sump system with the requisite coolers and 16an lines to a right side behind seat tank, smaller race battery back right, cool suit system and a 26 gal fuel cell at the rear (and still have rear aluminum bumper). We stay right at 49+ / 50+ front to rear but are always fighting shock heights for the side to side and cross weights.

BC

I have just the car for this once the kinks and "it's a Secret" issues are all worked out.

mark kibort

I find it hard to imagine how you get 49-51% front to rear, considering with gutting the car you end up with a repeatable 54/46% weight disty because all 928s are near the same. however i do understand that the engine is lighter but so is the transmission in your config.
3050 with 8 gallons of gas is near fighting weight and is very light compared to most GT high performance car in any racing series. most vets and vipers weigh in the 3100lb range with driver and some gas. mine weighs 3000lbs with 8 gals of gas and anderson was around 2900lbs.
that 16 quart dry sump is not as heavy as it might seem, understanding that oil is only around 5lbs per quart, so thats only about 10 extra lbs. I woudl remove that rear bumper, from a polar moment of weight. cant do much for side to side weights nor front to rear unless you end up moving stuff, but cross weights are the only thing you really have control of with ride height.

when is the car going to be at the next event?? i want to see it??

are you going to enter some races this year????

Mk

IcemanG17

MK
Remember his engine is 100lbs lighter than ours....thats why his front-rear is better...

The early 16V cars are much lighter....my car was 2926lbs wet with me (200lbs)...before I took 95lbs out of it......so that makes it 2835lbs now...

Aspkiller

Good observation. I went back and got the weight sheet that was done after I re-did a few things and found that the last NASA sheet said I was calc'd at 3350 with me and a couple of gallons. Which means that my empty weight was at least 3150.

Actually, there is a lot of additional weight with the big fluidyne cooler in front and a pair of coolers in the rear for the tranny and diff. Also have catch tanks for tranny, diff and oil tank, and an electric pump for diff. Seems like whatever we do to become more reliable adds weight. And it takes 16qts to change oil, but we don't completely drain the system each and every time. 16an lines full of oil ARE heavy.

All of the weight issues would be important if we really cared about winning anything. That may sound disingenuous, but building the car has actually been more fun than running it. And the main reason we take it to any of the tracks is to see what effect the last changes have made to it. If every day was 50 degrees, dry and 10 miles from home, maybe a different story. Last time at TH, the temps were over 100 and we were slower than before the sequential. Downshifting with a super lightweight clutch/fly is an art form that needs lots of seat time. Also went with new pedal set-up with manual brakes and that was a very scary feeling first time out trying to find brake points and balance.

I'd still be in Tahoe if I hadn't blown out my rotator cuff in August. Waiting to see if it will be therapy or surgery. Hopefully will be able to do Infineon or TH a few times next year. Mazda too far and I'm too noisy. Right now I can't get myself in/out of the car without major pain. Don't get old.

IcemanG17

Larry
Bummer about your shoulder.....I disclocated mine in April...a WEEK before a race weekend!!! I still made the race, driving was fine....getting in-out was PAINFUL....

It is quite fun tinkering with the car.....could be something big or small or theoritical but its VERY rewarding when a change equates to faster lap times!!!

Aero is next on my list....should have it finished by spring....2 seconds per lap faster is the goal....some prelimary calculations show a HUGE gain in G forces.... .25G more....

xschop

I saw a 6l80 at a shop yesterday and looks like it is no wider on the sides than the 6 speed manual. It's girth is all at the bottom of the case....FYI

My question for the Guru's is did Porsche lengthen/shorten the body/trans tunnel between years? Or was it just the Torque tube length change that I've seen posted with measurements (30mm)

mark kibort

????? Really?? I want to see these calculations. how much downforce can you generate putting on a splitter and wing of normal size around turn 2 for example?? ive measured the rear downforce at 80mph, its not much. only about 100lb at best. you do the calculations with that, ill give you 100lbs up front as well. I dont think that equates to .25g's at 70mph running around turn 2. figure it out and tell me! put it this way, you got a lot more from putting on slicks than you ever will get with downforce vs the DOTs.

sorry about the shoulder! I got one of them too!
so, that weight sounds more reasonable.
sounds like the car is a blast. look forward to seeing it! Let us know when you plan to come to sears or TH!

Aspkiller

Actually, we're both wrong!! It's Sonoma Raceway now.

slate blue

Yes to move the weight rearwards will help the handling, while it might vary to a minor degree depending on various factors like tire width, the optimum weight distribution is front 45/55 rear. Studies have shown better steering response, better ability to put power down and better weight distribution under braking.

When they designed the new ZR1 they made no attempts to lighten the rear of the car, the designer saying that this would be counter productive. This is why all the carbon parts are on the front end according to the chief designer.

mark kibort

removing weight is always best. you will never get the balance to that level. a street 928 that is cut to a race car shell, (everything removed) will be 54 46%.

no lighter enginer of 100lbs and a lighter transmission will help this.

as it is, the best we have all seen is about 800 to 850lbs in the front and 500 to 600lbs in the rear. even if you drop 50lbs a side (100lbs lighter vet engine) that is only 750 a side up front. all that extra oil is still only about 10lbs (8 extra quarts)

all the moving around stuff , like lighter battery, but put it in the rear passenger side, remove battery box, lighter starter, etc etc, still doesnt change the % disti much. as i mentioned you cant change the side to side weights much or front to rear, but you can get the cross weights near perfect.

weight distibution has different effects for different car handling functions. 50/50 is not perfect for all handing. rear weight favors accel, front weight brakes, certain side to side weight is better for left or right turns. its up to the race team to decide the trade offs and put the weight places that benefits most of the time for a given track.