Robert Linton

As we begin the R&D for what was to be a normally aspirated 4.0 liter engine, the question is should we go to a smaller displacement turbo instead?

demonfish

how about smaller twin turbo... then stick with the 3.6...

tis what i'd do, funds allowing.

Robert Linton

That is what I am thinking.

JasonAndreas

Normally aspirated 3.6L with a 13k RPM red line and it has to have the potential to remain a daily driver.

ilko

I like the idea of a NA 4.0L. It's very different from everything else out there (just like the car).

Colin 90 C2

I'm with demonfish. 3.6L, 9.0/1 compression, 2-gt28rs turbos, conversion to mass air. And you may want to start with 993 h/e's.
I have the complete plan, just not the funds to execute.

tony.t

In order of preference;
NA
centrifugal supercharger
turbo

turbo solutions always seem to run up against how efficient the intercooler is. For an equal hp level NA always seems to be the more elegant solution.

DAVISRILEY

Well, what about the 4.0l with a 10-12k redline, and daily driver capabilities? Can you imagine how either of them would sound?

Geoffrey

Given your quest for lightness, I would stick with a large displacement N/A engine like you originally planned. The turbo components add about 100lbs to the car in the wrong location. Having had both, I much prefer a non turbo car for real world driving and I'd wonder how well the Tip trans would do with a turbo engine. Just my $.02.

Robert Linton

But Geoffrey, think of the beautiful Secan intercooler.

Geoffrey

No doubt, they are beautiful. I've done so many MoTeC Turbo cars and I always return to liking the simplicity of the N/A engines.

Cupcar

Lots of people have smaller displacement air-cooled Turbos - there are only a few air-cooled 4.0 Liter 911s out there and none factory built.

Not to mention the throttle response and light weight of the N/A engine is hard to beat.

earlyapex

I always prefer a NA motor to a turbo or SC'd one. They sound better to me and I prefer their driving dynamics.

tony.t

but unless you are able to come up with a better intercooling solution than the Secan you have hit a celing at which no more power is readily available.
No doubt the turbo installation can be made lighter than 100kg though.

ltc

I had simply assumed the car was already equipped with M64/GT1 derived powertrain with KERS.