Big six engine choice impressions, My favorite was surprising Options

[campbellcj]

Great write-up and I've had a lot of fun with my fairly extreme carbed 2.7 but alas it's got a leak that will require a teardown someday to fix. Runs so well that I am putting that off as long as I can.

Can you describe "fairly extreme carbed 2.7"

Last time the engine was apart I had some new 2.8 P&Cs and I wanted to go higher compression with Mahle Race pistons but there were supply-chain/lead-time SNAFUs and my bank account was running dry so stuck with the existing cylinders and JEs which were reusable.

Pasted in from my notes file -

 2.7 (90mm bore x 70.4mm stroke) rebuilt and race-prepped by Galen Bieker (December 2013) on early 7R magnesium case (#6342207); line-bored; timeserted; oil mods; new 930 oil pump; STD/STD crank; 90mm Mahle Nikasil cylinders; 10.5:1 C/R JE Pistons
 Doherty Racing Cams (DRC) DC42 "mod S" cams; ports 38mm intake/34mm exhaust; flowed and polished; decked for increased compression; new valves and guides; polished and rebushed factory rods; new OE rockers; ARP fasteners; AASCO racing valve springs and titanium retainers
 Dual Weber 40IDT3C carbs rebuilt and rebored to 46mm by Bieker Engineering; PMO tall manifolds; K&N filters with flat metal tops (watershields in spares); PMO billet fuel bars; solid metal lines thru tunnel and braided AN-6 lines elsewhere
 JB Racing magnetically-triggered twin-plug distributor; Dual MSD-6AL CD’s and matching coils; MSD plug wires
 Carrera pressure-fed chain tensioners
 Turbo lower valve covers and sheet metal modified for twin-plug
 Series 900 911R/RSR style raw fiberglass shroud and air blockoff
 Short-geared 901 5-speed gearbox (A,GA,Ka,Q,V) extensively overhauled summer 2022 by TLG Auto including NOS R&P; 904 mainshaft and GA 2nd gear; new CMS billet intermediate plate; refreshed Guard TB differential
 Fresh sport clutch disc, pressure-plate and lightweight flywheel summer 2022
 237bhp/199ft-lbs at rear wheels (POC official dyno 2017)

Peak power is around 7500rpm w/ these cams

[JmuRiz]

hmmm sounds a lot like my build....I've wondered about springs and retainers, but I'm planning on stock as I don't see myself doing anything bur street driving. Single plug Mahle 9.8:1 2.8 pistons and DC40 cam is a bit more mild.

What says the brain trust? My engine and transmission guys say it's not a big deal when I won't be spinning it up to near 8k rpm anyway.

[slivel]

hmmm sounds a lot like my build....I've wondered about springs and retainers, but I'm planning on stock as I don't see myself doing anything bur street driving. Single plug Mahle 9.8:1 2.8 pistons and DC40 cam is a bit more mild.

What says the brain trust? My engine and transmission guys say it's not a big deal when I won't be spinning it up to near 8k rpm anyway.

I'd encourage you to spend the money on racing valve springs and titanium retainers capable of 8000 rpm even if you don't plan to spin the engine that high. One money shift that saves the engine will make it all worth the cost of the valve train upgrades.

[gandalf_025]

I was lucky enough to have my mechanic build a 2.5 for my car in the mid 80's

The 66mm crank with the 2.7 p+c's makes for a fun, quick reving engine that ran fine without extra oil coolers so no need to cut the car up..

That would be my first choice and my second would be the 2.8 based off the early 3.0 case.. That would probably require oil coolers though..

[davehg]

Both my 3.2 and 2.7 914's have front mounted coolers and I actually struggle with getting the oil temp to get to 200-210 - it's often closer to 190. The 3.2 runs a large oil tank with about 12qts, the 2.7 runs about 10 pts including the lines and cooler but with a stock 914-6 oil tank.

In contrast, the stock 2.7 of my 74 911 (nothing other than the engine oil cooler) would see temps as high as 230 in SoCal - after I installed the front fender cooler they dropped to normal (200-210). Here in the PNW we don't see strong temps like in the south except in rare July/Aug heat waves.

[brant]

My 2.1 uses two front coolers as well as the stock /6 oil cooler
It generally only see’s 5k - 8k
And often see’s 240-250f

But track only
Oil temps are not a direct correlation to displacement
More about compression, rpm, and use