2.4 Engine Build advice

[Phoenix65]

This board is amazing. I’m pleasantly surprised that Phoenix and her story are remembered��
Engine building is not my forte hence all the naive questions.

If the current engine was the original numbers matching, I would certainly mothball it and start fresh.
Unfortunately that ship sailed in the original engine fire / MotorMeister story. They kept the 7R case and left me with one from a 72. The engine was since rebuilt by Farbacher Loles before they folded. This build is as much about increasing mid range torque as it is about purging the history and building it right this time around. The challenge is I don’t really know what the “f” I’m doing. I have just enough knowledge to make it/ me dangerous. Hence the myriad of question and clarifications. (Yes, the 46/49 was a typo (also have fat fingers��)). I‘m on a steep learning curve and have ordered Bruce Anderson‘s book.

So what I’m hearing is the follow would be a worthwhile build... correct?
- CR of 10.5:1
- 93mm bore
- keep 70.4 stroke
- crankfire ignition
- PMO EFI w/ Clewett (I prefer the sleeper look)
- GE 30 cams
- ARP rod and flywheel bolts
This should net close to ca190ft lbs of torque.

What else should I be considering?
- lighter flywheel?
- special Clutch?
- oil flow mods?

Want to learn as much as possible before I open the wallet for this and live with this engine for the next 80k miles.

Many, many thanks... Oliver

[G69]

LoL Exactly Ed.

I once owed a R100 motorcycle that had come in 2nd in Daytona's Battle of Twins. It was a cobbled up race bike and had no real value so a friend (who raced it) sold it to me for a song.

Wasn't he surprised when I told him he was far short of WOT!
The throttle and linkage pinion gear was a tooth short of victory.

HaHa

It isn't a huge gain unless it is a down-to-the-wire situation. But then critical none the less.

I don't mind second.... Let the rest kill themselves and end up 5th or lower.
Second is just fine.

Always check for WOT!!!!
Have a safe Holiday!

[304065]

Oliver, listen, these motors are not swiss watches. If you can follow the directions to build a model airplane you can easily build a 911 engine.

In addition to Bruce's book, which is really a manual of how to identify all the performance parts Porsche used over the years, you should get Wayne's book How to Rebuild Porsche 911 Engines. While not perfect, it is the best single volume to educate yourself with. That and the Factory Workshop Manual, which is probably available online.

You will need some fairly expensive special tools if you are going to do it yourself, which I highly recommend. With Newton looking over your shoulder you should be fine. Tom1394Racing is also a local authority on the subject.

Engine rebuilding is 20% mechanical aptitude and 80% research and planning.

[blucille]

Why not post the engine number for the 72 block you have and the engine number that should be in your car, you might just have or find the needle in the haystack.

[lkadams]

Oliver, listen, these motors are not swiss watches. If you can follow the directions to build a model airplane you can easily build a 911 engine.

In addition to Bruce's book, which is really a manual of how to identify all the performance parts Porsche used over the years, you should get Wayne's book How to Rebuild Porsche 911 Engines. While not perfect, it is the best single volume to educate yourself with. That and the Factory Workshop Manual, which is probably available online.

You will need some fairly expensive special tools if you are going to do it yourself, which I highly recommend. With Newton looking over your shoulder you should be fine. Tom1394Racing is also a local authority on the subject.

Engine rebuilding is 20% mechanical aptitude and 80% research and planning.

another handy book is Cole Scrogham's reassembly manual.
http://www.lulu.com/us/en/shop/cole-...t-6270194.html

Oliver I like where your head is at in terms of drivability. If my lotto numbers ring in and I get to build another motor, I'd go with a Rasant injection and management system. Turn the key and go.
https://rasantproducts.com/rasant-pr...rottle-bodies/

Good luck with your project!

[Phoenix65]

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

[lkadams]

Oliver - what heads are you planning to use? That will be a factor in your cam choice. If you want higher lift, then bigger ports are better. I am using DC30s in my build, but using smaller port T heads for better low end torque. Can't tell you what it drives like, because I'm not done building it yet

[larwik]

Hi Oliver...Just in case...please read Post #269 on this thread below(or search "sprockets")...Best of luck with your engine-project.../ Lars...

https://www.early911sregistry.org/fo...ight=sprockets

[NorthernThrux]

Oliver, I'm following this story out of engineering interest, but I do want to point out that a stock 2.4S with 1mm overbored pistons and just a multi-angle valve seat grind and a revised MFI space cam (the latter not relevant to you if you go with the nice Clewett solution) can generate 212 hp at 7100 rpm and 175 lb-ft of torque at 5400. If you open the ports or use larger valves you will lose air velocity and torque down low.

So you do not have to do all the mods you are contemplating (except for fun!). Just the fuel injection mods you want to do and the valve seat grinding will make the hp/torque you want and do it reliably.

Ravi


EDIT: I see you have a T motor. I missed that. I'd then follow JackMan's suggestion below rather than mangling your motor.

[JackMan]

Oliver, read, study, ask questions, read more, ask more questions, listen.... once you choose a rabbit hole you cant go back. Personally, I would pull the stock engine and keep it to maintain resale value and originality. I would go with a 3.0 alumin block with carb PMOs and Mahle pistons and cylinders. More torque, cheaper to build and maintain. It's what I have in my backdate 1975 to 1970 long hood looks. I'm more than happy to chat on the phone and share with you all the details of the rebuild. That way you can learn from my mistakes. I love twinplug, but if that's an original numbers matching engine, don't mess with it. Even if it's not original matching numbers. The key is displacement with a device to mix the air and fuel to a 14:1 ratio. There are thousands of ways to accomplish this. Bruce Anderson's book is a great start. And don't forget to troll this website and pelicanparts. Both have many build threads. Learn from other peoples mistakes and copy their successes. Good luck and the color on your car is phenomenal! Looking for to your build thread. I you go with the 3.0 i would recommend some changes to your gearbox to accomodate the extra torque.