2.4 Engine Build advice

[Phoenix]

Thank you all for the continued advice. This will be a journey. The engine will be pulled from the car in a few weeks time. Having other bits worked being done while she’s sitting idle (wiring, trim refinishing, making sure all the switches and lights work, LEDs all around for better night vision, etc...) as I plan to drive her much more frequently than in the past. Tear down is planned for the summer with the build over winter. Goal is to be finished by next spring. This should provide ample time to get it right. The builder at Auto Associates is great and has done some relatively minor work on Phoenix before.

The engine is unfortunately not the original. The infamous MotorMiester took care that many years ago by “misappropriating” the 7R case without informing me. (There’s an old thread on this here or on Pelican.) Took me a while to find that out. I also believe they were the fundamental cause of the engine fire. The current case is from a ‘72t. After the fire, Farnbacher Loles rebuilt the engine again which I got back just after they closed up shop. This build should purge all past sins.

I want this engine to be “right” (fun spirited drive w/ low end torque) and last a 100k (reliability/ bulletproof/etc..). I’m still working on the build sheet which is continuously evolving based on what I’m learning here and on Pelican from all you fantastic experts. The current build sheet is as below. I would like to make this sheet as detailed, transparent and thought through as possible to ensure the builder and I are on the same page. Any advice on filling in the specifics is VERY much appreciated. Of course all must stay in budget which is good but not unlimited.

Phoenix Engine rebuild:
At the moment the thoughts are:

- 93 P&C‘s nickies w/ J&E’s
- 9.5:1 CR
- 70.4 stroke (existing)
- PMO 40 (existing)
- Mod S cams
- ARP rod bolts
- ARP flywheel bolts
- ARP head studs
- Time-cert threaded inserts
- Case savers
- Keep current exhaust and SSIs
- Front mounted oil cooler

Still open and being discussed are:
- pistons: Mahle vs JE. Why not German made Mahle? Have JE really rectified there past reliability issues?
- Port Heads 36 (S specs)..?
- Port Inlet trumpets 38 (S specs)... ?
- Throttle body to match heads and inlet trumpets... ?
- Narrow the cooling deflectors/tins
- Lightweight Rods to match the lightweight P&Cs? (Pauter / Carrillo?)
- Pressure plate... lightweight?
- Clutch disc...? (I believe there is a Sachs in it now)
- Flywheel... aluminum? lightly shave OEM/ steel?, standard OEM?... goal is to balance free revving with Streetable. I heard there are stalling and chatter issues if it’s too lightweight.
- Engine mounts. Do we need to change these to help manage the increased torque?
- Steel/ stainless steel fuels lines wherever possible (reliability and to prevent leaks... anything to prevent a 2nd fire!)
- Case... Original 7R is gone. Would love to find another. Other obtainable / affordable options?
- Transmission gearing. Would there be a noticeable benefit to changing the transmission gearing to better/ best fit the new engine Dynamics? (It must be worth the cost as the transmission has already been rebuilt and now also has a LSD.)

I’m hoping to complete the build sheet by the end of next month or so to ensure there is plenty of time get parts and line up good machinists. The process so far has been enjoyable and I’m learning a lot from here, PP, Bruce’s book, etc...

Thank you all for your support! I‘ve asked the builder to send me lots of fotos of the tear down and the build which I will post here. I will try an post a foto of the current motor. I suspect the final build won’t appear much different to the casual observer though what lies beneath will become a different story... a good sleeper.

Many thanks to all. Stay safe and healthy! ... Oliver

[66S]

Id consider switching to 46mm PMOs.

[Phoenix65]

Hello 66S... "Id consider switching to 46mm PMOs." what do estimate going 46 PMS would bring? better lower end torque?, more HP?, other?


With the IMMENSE help from this board and working with Scott @ Auto Assoc. who will build the motor and we've pretty much landed on the following specs...

• 93mm Mahle Pistons (machined to 9.8:1 compression ratio compression from 10.3:1 to avoid twin plugging)
• LN Nickie Cylinders
• Existing 70,4 stroke
• Mod S cam (objective is for strong torque starting at 1,88/2,000 rmp)
• Pauter or Carola rods
• ARP rod bolts
• Port heads to 35mm Exhaust
• Port heads to 36mm Intake
• Oil pump…rebuilt by Glen Ye
• Throttle body to match /again… maximize low end torque)
• PMO EFI system (engine management system of your choice)
• Stainless steel fuel lines from tank to EFI: Aeroquip or other alcohol safe lines (want to do all I can to avoid another fire)
• High pressure fuel pump
• ARP head studs
• Time-cert threaded inserts/ case savers
• Shuffel pin case to reduce flex & movement
• Engine case… current ’72 case or ’73 7R case if locatable
• Aluminum pressure plate
• Stock flywheel
• ARP flywheel bolts
• Engine mounts… using club sport mounts


My only concern at this point is if it's worth getting the 93mm Mahle's and shaving them down to 9.8:1 CR or going with JE's and no shaving. (Trying to avoid the added expenses of twin plugging).

What does the board think?

Once I get past this, the difficult part starts... waiting, and waiting and waiting while resisting the urge to continue tweaking as this build won't be completed until Spring of next year.

Stay safe and healthy... Oliver

[Richy]

I am not a fan of JE's , I've disassembled low milage engines with J&E pistons and the piston skirt wear was very alarming . A reputable engine builder told me his experience of running an engine on a dyno with J&E's , changing to Mahle P&C's and seeing more hp on the dyno. I am sure there are people who do not want to believe this .

[geneulm]

There are a lot of very proven combinations here that will give great performance and if built properly will last a long time.

I don't think you can get anywhere close to 9.8 with rsr 93mm using standard heads. These are 10.3(ish) with Rsr heads. Much closer to 11:1 with standard heads. Lots of folks built single plug 2.8 back in the day... but this is not a long lived proposition.

Mahle made runs of 9.5:1 92mm. This would be the gold standard. Newer JEs are MUCH better than those 20 years ago. These are good equipment now.

I would NOT do 46 pmo on a 2.7 for a street motor. Getting any advantage out of these will require 8k rpm and rsr type cams. All at the expense of area under the curve. Ge30/E/solex = more torque;S/ge60 for more at the top. My old auto x 2.7/E cam was a touch faster 0-50 than my 2.8/ge60 twin plug... which produces more top end HP.

Folks debate this now but I would do some sort of shuffle pinning on an old mag case -- especially if used with the long stroke crank. Look for a 7r case if you can. These are around (I have a spare I'm willing to part with).

[Phoenix65]

Thank you geneulm! Very helpful!
I may be interested in you 7R case. What is the history/ condition/ case #/ cost?
Best... Oliver

[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

This is a terrific engine with strong pull for both fun in the twisties and very manageable on the street. Wish I had it for the past 20 years!

[Phoenix]

And of course the final performance curves. Dyno done at the wheels…

[karlusmagnus]

Very nice Oliver. You must be chuffed. Beautiful car and the new engine is the icing on the cake.

[Phoenix]

Thank you Karl. I am.
It’s been a longtime coming and took quite a bit of thinking and advice to get there; including much from the kind experts on this and Perlican‘s boards.
There are advantages to keeping the same car for 20+ years and continuously refining it as situations allow.