Working through some things, need Speedo advice

[basiones]

So, about a year ago I purchased my first (and to date only) Porsche. A 1986 951 with 88,xxx miles on it that had had a fair amount of work done to it. The breaks and suspension had been upgraded, new wheels, new radiator, bigger turbo, some changes in plumbing, etc.

Now first of all I'm a computer guy, so I can't even give you a real good list of what's in it. A lot of the work was done by the previous owner's mechanic who is mostly a Mini guy (though very well respected in that field), so the guy who's done the most recent work on it (Chuck Miller at Millersport Auto) is learning the car, as it were.

So I just got it back after my first big service (timing belt, water pump, oil cooler housing, some freshing to the PS rack, new oil pressure sending unit, new oil pressure relief valve, new balance belt, a bunch of seals, etc.) mainly for peace of mind, and then when Chuck had it he noticed some oil leaks to tighten up.

So now I think I just want to ahead and make it a happy car, so I'm looking at the other things to mess with, and one of them is the speedometer. It's off, likely because of the 18" wheels on her. Does anyone have any idea how I would go about fixing that?

[jmj996]

Sounds like you picked up a really nice car. Computer guy here since I was 10 yrs old, but also a car guy since I was 15 yrs old. I think you're really going to enjoy this car. It's nice that you've done all that extra work to freshen it up, but that had to be really expensive. At some point I think you should try to start doing as much of this stuff yourself as possible, because it's going to be very expensive to own otherwise. It's not an ideal car to learn on because of the extra intricacies of turbocharging and computer control, but it's still a nice car to start getting your hands greasy with because there is soooo much documentation and numerous how-to guides for various 951 maintenance and upgrade projects out on the Internet, as well as awesome 951-specific aftermarket support (or you can even go to a Kragen or O'Reillys and get things like a fuel injector reseal kit or a rebuilt starter the same day).

I'm not a tuner (yet), but being a computer guy, I'm heading that direction as soon as I'm ready to take the big, expensive jump in HP. I think you would have the most fun with this car trying to implement a good EMS with a lot of sensors (i.e. add things like intake air temp sensor). My main focus for now has been the brakes, suspension, and reliability for the track. I still need a roll bar and some other safety stuff before I go big on HP increases. I'll be going the route Nize took, with an independent Engine Management System. Fortunately for you, a lot of the expensive hardware has already been upgraded for you, so you've got a big head start.

I can't tell you what to do about the speedo. Personally, I wouldn't go through the trouble. Just use the calculator on Clarks Garage and theoretically determine how far off it is, then do a drive-along with cell phones to see if it checks out on someone else's speedo (just don't use a Japanese import for the drive-along because they are notorious for being a little higher than actual speed - Nissan has even had to extend their warranties due to being high by more than 5% on a lot of vehicles, which results in the speedo showing more mileage than actual).

[Pops944]

You might try using a GPS. Stand alone or computer to check your actual speed. I like the computer because I can set it to record the data as I go. Just use a friend to watch the GPS mileage while you set your speed constant like on an interstate. From there you can determine how far out you are on the actual speed.

[nize]

use the stock 16" fuchs wheels.

[Pops944]

I wish I had the stock wheels on mine. Previous owner mounted 17's and clearance on the rear is tight. Unfortunately, the 16's cost more than the 17's and I'm already trying my better halfs patience. But it is still a great ride.

[carsontc]

what about one of these?

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=311/home_id=59/mode=prod/prd126.htm