2.4 Build

[cmcfaul]

The compression is always a little higher then advertised because the heads get machined, increasing compression. If I did the math right, my JE's should have been around 9.8.

[OCG911T]

Chris,

Is there any chance you could provide any details on our AFR Meter setup? I am looking to install one in my car and was originally thinking on hiding one in the glovebox but your setup sounds cool and I could actively monitor it.

Thanks!

Oliver

[OCG911T]

Oliver,

I’m enjoying this thread. I’m in the same process as you but have already gathered almost all my components and am now sending items out for machining/restoration/testing/etc.

My build details:
2.2T case- squirters, oil bypass mod, case savers, cylinder and case halves decked and then bored to standard

66mm counterweighted crank- magna fluxed and micro polished- not 100% sure on whether to cross drill, but will use clevite bearings and if I don’t cross drill will use bearings with an extra thousandth of clearance

87.5mm LN Engineering Nickies

9.5:1 JE Pistons

Carillo Rods with standard hardware

Stock flywheel with ARP Bolts

Stock clutch

Weber IDS Carbs (these are from a 67’ 911S and have additional squirters which apparently helped with detonation issues at the time by providing a small amount of extra fuel to enrich the mixture under hard throttle conditions, from what I understand at least.)

Cylinder heads full machining/valve job, ported/polished heads to S specs and sport springs and Ti retainers

Carb runners opened to match intake ports

DC40 (Mod-S) camshafts

Oil Pump- 4 rib ported/polished by Glenn Yee

Single Plug- Distributor re-curved by Barry Hershon at the Distributorlab, essentially rebuilt to S specs from the sounds of it with 7300 redline

MSD ignition module with blaster coil

ARP head studs

Carrera chain tensioner upgrade

SSI heat exchangers with M&K 2 in 1 out Sport Exhaust

My goal is to have a more powerful but reliable engine that I can bring up to 7300 without any worries. I also was torn over the cam selection as well as staying single plug. In the end after listening to all the helpful people on both forums I went with the Mod-S and will stay with single plug. I have a second engine that I will eventually make something a little more tame out of, like a 2.3 with a DC30 cam and keep the torque and hp in the lower range but also not stress the rest of the engine as much as my current build.

Just a thought for you... what are you using for your ignition setup? If I was going to go with the PMO EFI, I would consider one of the Clewett Engineering set-ups... with the crankfire ignition it isn’t that big of a deal to just go whole hog and twin plug. I think with machining and extra wires/twin plug coil arrangement you are looking at maybe 2,000 extra to twin plug? Anyway, just curious what you are planning in regards to that?

I would definitely take care in regards to detonation issues... I know it is my biggest worry with my build because with 9.5:1 but most likely slightly higher CR, like many of the guys have mentioned and with high dome pistons these engines are right in the edge of needing the extra spark.

Keep us posted!

Regards,
Oliver G.

[OCG911T]

Forgot to mention, with the 87.5mm P&Cs and the 66mm crank the displacement is ~2.4. I decided to go with the 87.5mm P&Cs because I could leave the cylinder spigots in the case stock rather than boring them out for the bigger sizes. I originally was going to go for a 2.5 or 2.6 by using the 90mm or 92mm P&Cs with the 66mm crank. I also decided on the 66mm because I like the nature of the short strokes even though they lack the low end grunt of the 70.4mm throw.

[cmcfaul]

My AFR setup was cool and easy. I ran the wires through the glove box and made a mount so the AFR meter fit into the cigarette Lighter. I could simply unplug it and put it in the glove box when ever I wanted the stock look.

The wires from the O2 sensor were not long enough to make if from the Muffler to the clove box and had to splice in a few extra feet. Hid the splices in the rear tunnel access port.

Chris
73 911 E

[gsxrken]

Bumping this back up- did Automobile Associates do the engine over the past winter as planned? Last update nearly a year ago bud... come on!

[Phoenix]

Hello All,
As this build is now complete with 1,000 mile engine run just behind us, I thought I would post all the build details and the final performance figures. Thank you all again for your input and advice much of it being included in the final build which took 6 months plus to research, decide and confirm. The build taking another 6 months plus.

As it‘s been a while, here‘s a short recap of the ingoing build objectives: Strong torque between 1200-4500 (driveability), reliable starts, slightly better fuel economy (car will be driven).

Cutting to the chase of what was done and its effects:
Topline change: 2.4 ltr PMO carbed non orginal motor built up to 2.9 ltrs with PMO EFI system.
Work performed by Scott @ Automobile Associates in Canton, CT

Overall results far exceeded my expectations:
At the wheels (Dyno’d):
- Torque: 190ft lbs @ 5,500 rpm
- HP: 220 @ 6,300
Estimated at the flywheel:
- Torgue: 215ft lbs @ 5,500 rpm
- HP: 245 @ 6,300

Details of the build include:
- LN Engineering custom 93mm Mahle Pistons for 9.8:1 compression ratio
- LN Nickie Cylinders
- Existing 70.4 stroke
- DC 40 cams
- Pauter rods
- ARP rod bolts
- Port heads to 35mm Exhaust
- Port heads to 36mm Intake
- Valves ground and lapped
- PMO EFI system
- Clewett EFI management system
- Oil pump: rebuilt by Glenn Yee Motorsports
- 3.2 Carrera front oil cooler with factory brass lines
- High pressure fuel pump
- ARP head studs
- Engine Case machined by Ollie’s
- Time-cert threaded inserts/ case savers
- Shuffle pin case to reduce flex & movement
- Reinforcing weld @ #3 cylinder
- Oil squirters
- Aluminum pressure place
- RSR style flywheel
- ARP flywheel bolts
- Narrowed air deflectors
- Club Sport engine mounts

Transmission/ Shift
- LSD transmission
- Shift bushings replaced
- NOS Aluminum pressure plate
- Release bearing replaced

A few fotos as what is a post like this without them :-)

[Phoenix]

Here is a foto of the dyno runs. Note the runs were done with engine in the car meaning figures are at the wheels and not at the flywheel as indicated on the monitor.

The solid green line is the new 2.9 ltr after tuning. The dotted lines are the previous 2.4.