Engine building - which way should I go?
 

Fellow Pelicans,

I have a dilemma, and seek your opinions.

First, the background. I have a 72 911 which came with a 2.7. I bought this car with the intent of turning it into a 2.8 RSR replica (because I love the body style and what the original race cars accomplished on the track).

So here's my dilemma: I have the 2.7 4R case and various bits that went with it (but no carbs or MFI). I have also acquired, over time, a '77 3.0 case and 2.2 crank, and 3.0 twin plug heads with which I could build a short stroke 2.8. Do I build the 2.8 on the 4R case, or build the short-stroker? Eventually I would like to race this car - possibly PCA, but more likely HSR or similar - so I'm trying to make the decision now so I only have to build one engine vice two.

Thanks in advance for you insight and input.

First question that comes to mind is: Can you run an Aluminum case engine in a historic classification? If I were an aggressive competitor I might cry fowl. Most historic classes cut off the classes at 72' model years and therefore this would be a modern engine.

Then there is the issue of weight in a class that is held back by wheel and tire sizes. I agree that the hp:torque of a short stroke 2.8 will help this, but not the additional weight. I would love to have the ss 2.8 in my car if I was you...and you could always sell it off complete, but I would seriously check rules, if one engine is the ultimate goal.

The famed Motomeister has a 3.0 for the mag case now :) Not sure the biral cyl are what you are looking for in racing!

Do you WANT MFI or Carbs? Does it need to be streetable? Have fun or truely competitive?

You need to look at your (future) rules, if you truly want to do a 2.8 RSR body, the engine size you need to be competitive may be very specific.

Luke,

Definitely not streetable - this car will be track only. Certainly I would like to be competitive, but if I stay true to the original 2.8 RSR design (engine, suspension, etc) then I definitely won't be competitive, so I'll probably start out just for fun (DEs, TTs, etc) until I get the car completely sorted, get more seat time and determine just how competitive I want to be.

Your points are all valid - particularly the aluminum case point, which I had not considered - and I thank you for taking the time to respond.

Andy,

You're absolutely right. I'm really torn on which way to go, but have a feeling I'll gravitate toward the HSR-type racing. I just don't have the money to build a car that will be truly competitive in PCA GT-4 and still remain true to the original 2.8 RSR design.

Thanks for responding.