What can I build and is it worth it??

jcc911 · 10-27-2012, 06:18 AM

I know this is somewhat a loaded question as I am sure the reply is, "yes, depends on what you want to spend" or something to that effect.

Currently I am driving a 78 3.0 with ~88k that I converted to turbo using 930 CIS. Besides the CIS and exhaust everything else is SC engine internals. I had a valve job done about 10k ago, ported for twin plug ( haven't completed the ignition) and put in 993 head studs.

The car runs good, but I am sitting on some parts and was wondering if I should pull the motor and add them or not.
Can I put in a 930 crank rods and p/c? Would that be, 3.1? I know the c/r would be lower so I could add more boost, But in all honesty would it really be worth the extra time and expense?
As it sits right now the car was dynoed at 255 whp

Thanks guys.

jess p · 10-28-2012, 08:05 AM

Early 930 engines used a 2.7 crank, later 3.3 turbo used the same crank as
a 3.2 carrera. What you could do is fit 3.2 p/c or change the pistons for lower
compression.

jcc911 · 10-28-2012, 09:22 AM

Thanks, any one else?

Uwon · Uwon's Garage

What about a more modern engine management system such as Electromotive tec3r?
Handles twin plug like a dream and you can tune the motor to perfection for both street and track. Probably should look at lowering the compression as well to avoid granading with additional hp. Cheers.....

KTL · 10-31-2012, 07:33 AM

JC,

Your '78 930 crank, rods, P&C will give you a 3.3L in the SC case no problem. The 930 and SC main bearing bores are the same size so the 930 crank drops right in. Then your cylinder diameter (97mm) & piston configuration finishes it off to be a 3.3L

But if you just put in the 930 crank and rods, your current pistons in the engine won't work because the piston pin bore is larger on the 930 rods (23mm) compared to your SC rods (22mm).

Cylinder stud spacing & spigot sizing is the same on the SC & 930 cases. So all those parts you have will drop right into your SC case. Key is to get the rods hooked up to your pistons correctly. You could have the rods rebushed for smaller pin bushings. But you still have to figure out your pistons & rods because the the 930 crank has 4mm more stroke and 930 rods are shorter by .79 mm

255 WHP is pretty good! I'd tend to stick with that. IMO the SC crank is better (lighter) and so are the rods. Moving to the 930 stuff isn't necessarily a downgrade. You certainly gain displacement!

jcc911 · 10-31-2012, 05:10 PM

Hey Kevin, thats great info and advice, thanks.
Looks like I have some stuff to sell.