2.4 Build

[lvporschepilot]

A local builder actually stopped having mag cases dowel pinned at each and every main journal as the lack of 'give' was causing stress cracks in blocks completely trashing the reusability of the block, so now he has them pinned at only 2 or 3 of the main webs. Mind you, this is only for motors starting to push above 240-250.

[Phoenix]

Hello all,
Back on this again after too many weeks of COVID-19 crisis management.

Planning for Automotive Associates of Canton, CT to start the build soon.

At the moment we are thinking the following:
- stroke as is at 70.4
- bore 92 mm Nickies P&Cs
- Mod S cam (or DC 30?)
- CR 9.5:1
- Existing PMO 40 carbs (keep costs down)
- single plug (keep costs down)
- front fender mount oil cooler
- case savers
- ARP rod and flywheel bolts

The estimate is that this set-up would bring torque to rough 175 with good low/mid range power and roughly 20ö-210 HP. This seems to be close to RS specs (being a bit generous here).

Are their any other watch outs I should be considering to increase either lo/mid torque or reliability/longevity?

Best to all. Stay safe and healthy.... Oliver

[cmcfaul]

Mod S and DC30 are basically the same. I used DC 30s and could not be happier. Anything you can do to lighten the top end will help. Mine was at full power band at 7300 redline. Would have loved to let go further. Will be a great engine! Keep an eye on temps and mixture. Lean is fast but can eat a piston.

Chris
73 E MFI

[targa72e]

DC30 are mod solex, this is the most aggressive that can be ground on E cams with out welding. DC40 are modS and require S or higher cams to start with for regrind. DC40 has a little more lift and duration than DC30. I just built a 2.7 with RS pistons and DC40 cams and 40 webers. I could not be happier with cam selection, great midrange with surge at top. Will be taking to Dyno once things open up from CV19.

john

[Trackrash]

My $0.02. Check the link here for cam choices.
Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles
Look at DC35, my choice. A little less duration than the Mod S (DC40), but more lift. Meaning better midrange, you may give up some at 7k rpm, but over all good power. Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles

Originally Posted by Phoenix

Hello all,
Back on this again after too many weeks of COVID-19 crisis management.

Planning for Automotive Associates of Canton, CT to start the build soon.

At the moment we are thinking the following:
- stroke as is at 70.4
- bore 92 mm Nickies P&Cs
- Mod S cam (or DC 30?)
- CR 9.5:1
- Existing PMO 40 carbs (keep costs down)
- single plug (keep costs down)
- front fender mount oil cooler
- case savers
- ARP rod and flywheel bolts

The estimate is that this set-up would bring torque to rough 175 with good low/mid range power and roughly 20ö-210 HP. This seems to be close to RS specs (being a bit generous here).

Are their any other watch outs I should be considering to increase either lo/mid torque or reliability/longevity?

Best to all. Stay safe and healthy.... Oliver

[Rosco_NZ]

Your specs basically the same as the engine I’m building .. other thing to consider is inlet sizing .. port heads and inlet trumpets to S specs, (maybe a little larger if you’re chasing hp) clean up throttle bodies to match 36 to heads, 38 to inlet trumpets.

[Rosco_NZ]

Should be good for ~230hp, more tq across time rev range.

[Phoenix]

Thank you all for the continued advice. This will be a journey. I’m mirroring this thread with EarlyS as not all are on both.

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, Early S, 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

[Phoenix]

[gsxrken]

Oliver- great to see this thread pop up! I remember your sweet car from many years ago on one of the Palisades runs. Nice to see you still have it and the passion for it to improve it further.

I don’t have much experience with the N/A motors but I would pitch in the following few remarks from years of hanging around cars:
1. Find a way to make the EFI happen. Nothing you can do will be more of an improvement.
2. Don’t bother with a 7k-ish cam... you’ll be there .0001% of the time but have to life with it the other 99.9999% of the time you’re not. Especially with carbs
3. LTWT flywheels and pressure plates have a 50/50 love/hate track record with users. Save your money for the EFI
4. Talk to Len Cummings about custom fuel lines from tank to injectors. Peace of mind
5. Mahle. Why screw around
6. 2 builders I know like ARP for rod bolts but not for head studs. Canyon/Supertec/993s
7. Don’t do everything at once. Transmission mods and oil cooler additions particularly can be shockingly expensive and drag out a project into infinity. Hit it hard, and return it to service and enjoy it. Next winter you can take the next base camp.

I like AA. Ken and Scott helped me with a small deer strike / front half repaint. They specify their own clevite bearings for these engines and I’m sure they’ll use them here.

Maybe we can get back out for another one of these Palisades / Hawk Nest runs. My son is in his final year at West Point and they have a great vantage point of Cold Spring across the Hudson. We’ve visited there many times over the past four years. Beautiful area.
Good luck with your build!

[Trackrash]

OK, my $0.02.

If you want midrange torque and instant response, without twisting to 6,000 rpm, go with a DC 35 or similar cam. Yea, you may loose some HP at 7,000 rpm, but you won't miss it. It is much nicer to be able to hit the gas at 3000-3500 rpm and have the motor PULL than wait to 4500 rpm for things to happen.

Stick with a stock flywheel, they are already very light. However, use the aluminum PP. That combination is the best of both worlds. Nice response, but manageable.

Get the motor running with the PMOs. Then go to EFI on a later project if you think you need it.

Go with Mahle pistons, IF you can get the correct ones for your build. However the newest generation of JEs will work just fine.

Carrillo or similar rods are overkill, but nice if you have the $$$ to spend.

Do the porting.

If you go to stainless braided fuel hose, make sure you get Aeroquip or quality that is alcohol safe.

[Phoenix]

Those were some fun runs along the Palisades. Hope to get back into it all next year.

I‘m still seriously considering PMO EFI and the cam goals is the range your indicating. Would be perfect for the Bear Mt pkwy and Schawangunk Mt roads. I may as well complete all the work now as I will not have an opportunity to use the car this year anyway. Scott at AA will assemble over this Winter.

Very much looking forward to it...

Originally Posted by gsxrken

Oliver- great to see this thread pop up! I remember your sweet car from many years ago on one of the Palisades runs. Nice to see you still have it and the passion for it to improve it further.

I don’t have much experience with the N/A motors but I would pitch in the following few remarks from years of hanging around cars:
1. Find a way to make the EFI happen. Nothing you can do will be more of an improvement.
2. Don’t bother with a 7k-ish cam... you’ll be there .0001% of the time but have to life with it the other 99.9999% of the time you’re not. Especially with carbs
3. LTWT flywheels and pressure plates have a 50/50 love/hate track record with users. Save your money for the EFI
4. Talk to Len Cummings about custom fuel lines from tank to injectors. Peace of mind
5. Mahle. Why screw around
6. 2 builders I know like ARP for rod bolts but not for head studs. Canyon/Supertec/993s
7. Don’t do everything at once. Transmission mods and oil cooler additions particularly can be shockingly expensive and drag out a project into infinity. Hit it hard, and return it to service and enjoy it. Next winter you can take the next base camp.

I like AA. Ken and Scott helped me with a small deer strike / front half repaint. They specify their own clevite bearings for these engines and I’m sure they’ll use them here.

Maybe we can get back out for another one of these Palisades / Hawk Nest runs. My son is in his final year at West Point and they have a great vantage point of Cold Spring across the Hudson. We’ve visited there many times over the past four years. Beautiful area.
Good luck with your build!

[Phoenix]

I think you and others have convinced me to stick with the OEM flywheel and go with Mahles. Will checkout the Aluminium PP. At the moment I‘m considering a Mod S cam. Do you see a DC 35 delivery more low end power band? I‘m not looking for a screamer and doubt I’ll be at 7k or more very often. I like the Carrillos as I‘m trying to reduce internal weight and get a more free revving engine. I‘m pushing the button on EFI as frankly I don’t want to go back later and do more. Would prefer to get it all done as I have the time and the funds. Hope to do nothing but regular maintenance and enjoy her once I get her back.

Many thanks!

Originally Posted by Trackrash

OK, my $0.02.

If you want midrange torque and instant response, without twisting to 6,000 rpm, go with a DC 35 or similar cam. Yea, you may loose some HP at 7,000 rpm, but you won't miss it. It is much nicer to be able to hit the gas at 3000-3500 rpm and have the motor PULL than wait to 4500 rpm for things to happen.

Stick with a stock flywheel, they are already very light. However, use the aluminum PP. That combination is the best of both worlds. Nice response, but manageable.

Get the motor running with the PMOs. Then go to EFI on a later project if you think you need it.

Go with Mahle pistons, IF you can get the correct ones for your build. However the newest generation of JEs will work just fine.

Carrillo or similar rods are overkill, but nice if you have the $$$ to spend.

Do the porting.

If you go to stainless braided fuel hose, make sure you get Aeroquip or quality that is alcohol safe.

[Trackrash]

The difference between the DC35 and DC 40 would be the DC40 will move the power band up the RPM scale. If you want a high RPM screamer, the DC40 would be the way to go.

With EFI there may be other options to consider.

You can contact John Dougherty, AKA camgrinder, at Dougherty race Cams and discuss your build with him.

[Rosco_NZ]

Mod-S cam in 2.7/2.8 doesn’t create too much of a screamer .. improves tq over 2.7RS. Note 2 versions of Mod-S .. DC40 has more lift than WebCam 464/465 .. check this option too as might be a more driveable 2.7 cam.

[911 SLANT]

Phoenix I just picked up my motor yesterday. Its set up with same specs. It was a 2.7. Now a 2.8 with 92mm J&E 9:5.1 pistons, MOD S cams,ported heads 41/35, aluminum PP and flywheel, 7:31 gear ratio on transmission, 46mm PMOs, Rarelyl8 1.5 OD headers and M&K GT3 muffler. Please let us know how your motor runs.

[G450X]

Originally Posted by cmcfaul

What Trackrash said. Higher compression with Mod S or DC 30 cams is a bullet proof application. Don't know why Porsche did not make it.

I had a 73 E... ran out of breath at redline 7300 RPM.
Upped the compression to 9.5....big difference
reground the E cams to DC30's....holy cow...screamer.

Combination of compression and cam with the right VE is the recipe you want.
9.5 CR and DC 30 cams on MFI 2.4 was an amazing engine.

Chris
73 E

Wow, complaining that your ‘73 E ran out of breath at 7300 rpm!

I am trying to get my stock SC, that runs out of breath at 5500 rpm (that’s a real let down, just when it’s starting to sound and pull good), to make it to 7,000 rpm!

[Phoenix]

As my goal is low-end torque, I won't be spending enough time at 7500+ to have any complaints. I'm getting my fill of high HP / high rev / high speed on the Autobahn while I'm here in Germany This build will be for spirited rides in upstate NY and New England.

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

[cmcfaul]

Sounds like a perfect spec. The JE's have deep valve pockets which help and give a margin of error (no experience with the aftermarket Mahle's) With cam change you may want an AFR meter to dial in the mixture. High CR + lean mixture= detonation. Plus it looks cool. had mine replace the cigarette lighter.

Chris
73 E

[Trackrash]

FWIW, my JEs ended up around 9.8 to 1 CR, from an advertised 9.5. Combustion chambers on my car were 89cc. So that may be the way to go for you as well.