Engine choices to mod a 73T coupe

[asianbond]

Just purchased a 73 roller, accident free, no rust with brand new paint and sc flares. Need advice for powertrain (engine, intake and tranny)

Looking to build a "gruppe R" theme vehicle. Goal is amazing throttle response with solid low end torque and perhaps the ability to keep up with modern exotics in straight line.

First choice

Stock 2.4 mod to 2.7 specs with mfi.

Second Choice

Stock 3.2, 3.4 or 3.6 off a carrera, 964 or 993

Third choice

Built 3.0sc motor with webers

[kenikh]

This should be you number one choice:

Built 3.0sc motor with webers

If you take this motor and drop in DC40 (Mod-S) cams with Webers and big port heads, you will be in for the ride of your life. I'd also consider 9.5:1 CR pistons from JE for more "pop". Also, make sure you build the rods with ARP bolts so you can spin the motor over 7000 RPM. This motor will exceed all of your expectations, cost less than a built 2.4/2.7 and be more fun than a 3.2, which has a longer stroke (which, IMO, makes the motor feel "lazy").

(Edit) Just to add one small correction, it is "R Gruppe", not "gruppe R". Cheers.

[Scott Clarke]

What parts do you currently have?

[WM711]

Kenik +1. Move third choice to #1

[jcarpio]

What an interesting thread!

Kenik, that 3.0 you spec'd sounds really cool. How would you approximate it's feel if you started with a 2.4 (MFI)? I'm guessing going the mod'd 2.7 route won't do this. If it's not possible, then what would you say the difference between the 3.0 you mentioned and 2.7 would be in feel? Thanks.

[Flat Six, inc.]

Kenik is right on!

[kenikh]

What an interesting thread!

Kenik, that 3.0 you spec'd sounds really cool. How would you approximate it's feel if you started with a 2.4 (MFI)? I'm guessing going the mod'd 2.7 route won't do this. If it's not possible, then what would you say the difference between the 3.0 you mentioned and 2.7 would be in feel? Thanks.

I would say that the feel of the 2.7 is similar to the 3.0 (same stroke), with the 3.0 making the expected 10% power premium due to displacement. That said, the 3.0 uses a sturdy aluminum case, while unless you are opting for the VERY expensive early sandcast aluminum case to build a 2.7, you are stuck with using a magnesium case. Even if you use the beefier later 7R magnesium case, you are going to get stuck with $1200 in machine work to get the case sorted to ZERO dollars for the aluminum case. Speaking of the sandcast case, it has its own machining bugaboos, so forget it.

The bottom line: same feel for the 3.0 as the 2.7, but with more power and less cost for only a slight weight penalty. What's not to like?

[gulf911]

While a built 3.0 is nice, a stock 3.2 with SSi's is less expensive just as bullet proof , way more low end torque and no messing with carbs. The 3.2 only feels lazy in a Carrera, not in a 2300lb early car.

[Longballa]

3.2 Short Stroke with MFI would be nice bolted to a G50. Oh yea! That's what I'm doing.

[asianbond]

This 3.0 engine is currently being built and has been offered to me:

"The engine has new JE 10.5:1 lightweight forged pistons, "S" specification cams by webcam, big port heads, new bearings and other interior engine parts. it is fully balanced. 40 ida's or 46 ida's. The transmission is from a later model SC"

Any estimates on horsepower this 3.0 would produce?

I am seriously considering going a 964 or 993 engine route similiar to the Jeff Smith car in recent issue of Excellence.

The car came without a powertrain, so I need to source everything from scratch.