Many of you are aware that I plan to enter the 25 Hours of Thunderhill this coming December, and that my preferred entry would be my C-Sports Racer. Well, after fully evaluating our options, we have changed course and decided to use an A1 Rabbit .
The principal reason for changing our minds is that after talking with the engineer who built my car, I am convinced that it can't last the distance. My car was originally designed for 30-minute sprint races as a 950-pound Formula Ford with about 100 hp. It now weighs 1300 pounds, but nothing has been upgraded for the additional weight or race distance, like brakes, suspension, electrics, fuel, etc. There is also the issue of racing aound the clock in an open top car at a time of the year when we expect to get pour ing cold rain, but the team was willing to do it if the car could reasonably be expected to last the distance.
Great... sounds like the decision is getting easier then
Anyway, for the past week or so I have been looking for an A1 Rabbit to build into a GTI Cup or SCCA ITC-type car (NASA will allow NA or TD diesels built to either spec). A few days ago someone emailed me that there was an '84 GTI with a blown engine available in the SF Bay Area for $100. Saturday I called the guy to check it out, but he said that it was no longer available...but that if I could wait a few weeks, he would GIVE me an '83 GTI roller (complete, less engine).
Whoa...! :shock:
Since I was driving within a few miles of his place later Saturday I arranged to go look at it. It's a black, base-model GTI in really good shape. Not even any major dents.
Awesome, that is great. Bodywork is a lot of extra expense and IMO it's worth finding a clean body to start with so you don't have to do this.
I say base model because it doesn't appear to have any upgrades except a manual sun roof
blech... optional and extra weight where you don't want it. But I suppose cutting it out and riveting an aluminum skin in pace is easy enough if you're not too concerned about cosmetric. :lol: Or you could just live with it and leave that as a "to do" for weight reduction later.
and the three-gauge center cluster (were those stock on even base GTIs?).
All A1 ('83-'84) GTIs have the 3-gauge center cluster.
It has manual-crank window
all Rabbits have manual window winders
no a/c
Good! That saves a good bit of work of having to convert it to non-A/C. The A/C adds a lot of exyta weight and various parts. I'd say avoid for racing application when possible.
no rear disk brakes
No A1s were factory equipped with rear discs. The rear 180mm drum setup is a lot lighter anyway, works find for many other Rabbit roadracers too!
base am/fm radio, manual seats, thin glass, everything! No rust anywhere (California car!), no damage or creases to bumper extensions, strut towers front and rear, or spare wheel well. All the lights, wipers, heater/defroster work. What a find! I can pick it up as soon as he pulls the engine. Oh yeah, it has the wide ratio 5-sp, so it should work well with a diesel.
No A1 cars had power seats. I don't know what you mean by "thin glass".
All A1 GTIs were factory equipped with close ratio transmissions. there is a slight difference between '83 and '84 models. The '84 GTI has the "4K" tranny, can't remember off-hand what the '83 GTI came with. You can find the transmission code on the bottom of the bellhousing, look for the first two characters.
But even if it's not the transmission ratio you think you'll need, good used transmissions are readily available, and since you will probably want to add a limited slip differential anyway, so you can swap transmissions easily at that time.
There's a lot of work ahead of me, but I'm glad to have this settled. Unfortunately, the Quantum's engine isn't a drop-in. I don't think the turbo will fit the Rabbit, so I'll be looking for a Golf/Jetta exhaust manifold and a stock turbo (K-24 or Garret 25?). Anyone have any thoughts on which is better?
True, the quantum exhaust manifold is not really compatible with transverse engine moutning. Unfortuntely with that transvere-mount exhaust manifold you won't have room to run that A1 GTI intake you've been hoping for. I've heard some gasser turbo conversions have successfully installed the stock transverse A1TD exhaust manifold upside down however. This would require re-clocking the turbocharger so oil goes in at the top and out at the bottom, take a look at whether that would be legal in your class.
NASA's diesel rules call for stock engine internals and stock turbo. Intake and exhaust manifolds are free.
Holey smokes, that sounds an awful lot like SCCA Street Prepared ruleset that I am running under!!! In that class, are wastegate modifications also not allowed? If they are restricted, then it seems awfully similar to SCCA SP engine modification rules.
PS - in the "which is better" turbo question, I haven't done any scientific testing, but now that I have both turbos I might be able to. Some speculate that the Garrett is quicker-spooling and works at a lower RPM and the KKK is slower reacting but more efficient at higher RPM. I haven't seen any scientific proof or anyone actually testing the 2 turbos back to back, however.
The KKK allows a provision for "fine tuning" the boost to the upper limit of the factory specifications... while the Garrett's wastegate is sealed. Could be something to keep in mind if you are required to stay withing factory boost specifications and not allowed to make changes to your wastegate - the boost on the KKK could be "blueprinted" to the top limit of the factory specs while that is not easy or possible with the Garrett. There is a greater than 1 psi range of the factory specs, and most turbos I have seen seem to be on the low side of the spec! So with blueprinting you can probably gain .5-1 psi. If you are limited by your rules as to what turbos you can run and at what boost pressure, a .5-1psi change is a significant difference!
FYI - on the issue of chassis weight. Are you allowed to remove options like power brakes, added trim, etc that is found in the later-model Rabbits, and/or backdate these items to earlier-Rabbit specifications?
If you are not able to remove items like this or back them to earlier Rabbit specifications, you should be aware that the earlier "base model" Rabbits had fewer weight-sapping features that the later model Rabbits had. But if your class allows backdating or removing the stuff, it shouldn't be a problem, just a little work to make the changes (but you can optimize everything for light weight while you do it.) You are smart going with a 2dr Rabbit model (as all GTIs are.) A clean, 70's base model 2dr, no sunroof would be the best find, but I'd say you've got a good find with that $100 clean non-A/C sunroof'ed GTI there.
Topic: Major Project Change (Read 9536 times)
