euro3.0 to 3.4
 

i have a euro 3.0 (Al case 76/77) and wanting capacity increase to 3.4 for tarmac rally 911. As well as 98mm pistons & cyls i'am thinking of maching a 3.3 turbo crank i have to suit case & machine case to accept larger rear main seal. Seems easier to machine crank down than bore case. Any advise please

I did almost the same thing if i understand you well.
I machined a SC engine case to fit 100 mm mahle cylinders.
Using a GT1 74.4 crank, titanium GT1 rods, custom made CP pistons, etc.

http://forums.pelicanparts.com/uploa...1164449762.jpg

http://forums.pelicanparts.com/uploa...1164449835.jpg

Rods;
http://forums.pelicanparts.com/uploa...1164452083.jpg

I did not know there was a 74.4 GT crank. I thought they were all 76.4mm. Didn't you mean 3.2 crank?

A GT1 crank is one whit a big main seal bore (9 Bolt)
It is much easier to get a later style engine case then using the older style Carrera 3.0 Engine case.


Here you a have the specs of GT1;
http://www.supercars.net/garages/marcusmv3/157v2.html

I think in your case I'd use the 2.7L crank with 100mm or 102mm P&C's and get a revvier motor. You'll appreciate the lightness of the crank since it's a competition car, the 2.7L crank was much lighter than the 3.3L turbo or any of the other 70.4mm stroke cranks!

Quite interested in this thread, I am basically assembling parts for a similar engine. I am using a new '84 case, with the Mahle 98mm P/C's 10.3 compression, Turbo crankshaft and Carillo rods. The heads are from my '79 Euro 3.0SC engine, so the ports ought to be fun. It will get twin plugged, TWM manifolds and one of the engine management systems, distributorless (CoP).

Result will be a 3.4...so I am not sure why the Turbo crankshaft would need to be machined? If you use the 74.4 crankshaft (Turbo or Carrera) and 100 mm P/C's you get 3.5 litre or thereabouts actually.

If you use 98mm P/C's with the SC (or I suppose the 2.7 litre) 70.4 mm crankshaft you get 3.2 litres like my Kremer 3.2......


Dennis

my reason for wanting to machine the 3.3 turbo crank is my case is 76/77 3.0 (uses 2.7 crank with smaller mains).I understand using my existing crank will give me a revier engine but i thought the 74.4 stroke turbo crank (which i already have one)would give me more torque i thought would be better for tarmac rallies & hill climbs(car will probably never see a track). Any more advice would be greatly appreciated

Your 76/77 3.0 case is special in that it can be used for building a short stroke motor with a 66mm crank. The later more common 3.0/3.2 SC/Carrera cases can't be used for building a short stroke (66mm) motor so this makes your case a more valuable commodity in the market due to it's rarity.

You would have money left over and avoid machining costs if you sold your case and bought a later case that fits the 3.3 (74.4mm) crank you want to use.