2.7 RS Spec Plus Engine!?

[Longballa]

So, say you were going to build a 2.7 RS spec MFI engine but with a little extra HP or CR what would be your ultimate configuration for an engine like that? Thanks, -Scott

[Flieger]

Twin plug and 9.5:1 pistons, or 10.5:1 if they make them in 90 mm. Titanium valve spring retainers, racing valve springs, titanium connecting rods or at least some lightweight steel ones like R+R. The valvetrain (springs) are what limited the redline and cam profiles of those engines, unless you count the flywheel shedding torsional harmonic at 8,000 with the 70.4mm stroke crank. I'd actually like to go back to 2.5 liters with the short stroke crank and try to spin mine faster.

[speedo]

I'm guessing Grady Clay would say....SS 2.8 MFI.

[Chuck Miller]

Scott,

I'd really have to think about what I'd do for the 'ultimate' 2.7RS + engine......

However, for a street car that's driven occasionally on the track, that basic set up is what I've been running with good performance and no problems for the last 13 years, for over 65,000 miles.

- My original 2.4 engine machined for the 90mm piston set.
- Mahel 911.103.928.02 Group 6, 9.5CR piston set.
- SC oil pump.
- WebCam 120/104 regrind cams.
- RS space cam in the pump.
- Lots of intake head work.

Man, that's about it....... My car still runs it's original 2.4S distributor and ignition set........

If I was to do this basic set up again I'd probably start with an 'early' or 'later' aluminum case......

Holiday Cheers,
Chuck

[Longballa]

Chuck, have you ever put the engine on a dyno to see where you're at HP wise? If you did it again would you twin plug it? Thanks, -Scott

[Mr9146]

Max is full of ideas, but he didn't read your post and he's a dreamer. Gotta love the youth.

The reality is that the 2.7RS motor was one of the best all-around performers Porsche ever built. But they used low compression pistons and gave up horsepower for the sake of what I like to call "production-line performance" (performance good enough for the masses). And compared to the 2.4S of the day it was still a significant jump so they left it alone. But, if you want to make REAL power with an RS motor, you add compression.

There are a hundred ways to skin a cat, but one works better than all the rest. Chuck's motor is pretty much the blueprint for the perfect all-around 2.7L; it's tried and true time and again, year after year, motor after motor. Small tweaks to the formula net a slightly different result, but stick with the basic ingredients and season to taste.

High comp pistons + lightly-profiled cams + slight head work + lightly-adjusted MFI system + factory heat exchangers + factory single-out sport muffler = winning combination.

[Longballa]

Cool, thanks Marco. I'm going to build this engine myself (or should I say under the very close supervision of Mark Jung) going to build the engine, MFI pump and the whole deal. Should be fun!

[Mr9146]

Cool, thanks Marco. I'm going to build this engine myself (or should I say under the very close supervision of Mark Jung) going to build the engine, MFI pump and the whole deal. Should be fun!

Then keep it simple on your first go-round. You must learn to crawl before you can run.

[Longballa]

Yes master!

[Chuck Miller]

Chuck, have you ever put the engine on a dyno to see where you're at HP wise?

Nope.......... Relative to the cars I can run with, if I were to make a good guess about 230/235 at the crank.

If you did it again would you twin plug it?

Nope, not with only 9.5CP, unless the U.S./Calif. octane standards REALLY take a dive, like Marco says, keep it simple brother...