3.0 rebuild - what would you do?

[GT2BH]

I've searched, I've read, and I'm more confused than when I started (probably due to lack of experience)

Carbs, EFI, CIS?
95mm 3.0 pistons/cylinders or 98mm 3.2 pistons/cylinders?
Stock cams, 964, custom?

Restrictions in the rebuild are as follows:
1) No pelicans near me to help out, which is a huge drawback
2) No machine shops which are specialized in Porsches
3) Parts should preferably be plug and play
4) I live far far away and shipping can get expensive

So basically I need to do this on my own, with minimal help from a machine shop. Budget is around $10k for parts. Car will be a weekend driver, spirited driving, weather ranges between 15c-45c, and we have no emissions restrictions. I can also run it on race gas if necessary since it won't be driven much.

[Sicklyscott]

My eventual plans for my 3.0 include

- 3.2 pistons and cylinders,
- either 3.2 heads or reworked 3.0 heads.
- twin plug
- 964 cams (or something more appropriate, haven't researched this yet)
- PMO ITB

I will tell you this build will cost more than 10k. Just the ITB and EFI setup I got was 4500 used. If I were in your shoes if probably go carb and save some money.

[RDM]

My own thinking is that if you're going to be dependent on help from a distance, the more stock your car is the better off you are. Troubleshooting a one-of-a-kind can be a lonely experience.

How much power do you need to be happy?

My experience: I rebuilt my engine last winter with help (Start with maintenance, end with disaster. Or opportunity). Mods were limited to 964 cams, SSIs and a freer-flowing muffler. I have more power than my limited skills can use on the winding roads around here.

[G450X]

I am facing a 3.0 rebuild also, this is what I'm planning.

98mm Max Moritz P&C's
Early SC (or Euro) heads, CIS, and distributor
964 cams
SSI's
M&K 2/1
Sachs power clutch with aluminum PP
Aluminum flywheel
915 with lower gearing

I have all the parts, I just need to have the used parts double checked for wear and have the heads rebuilt. The Max Moritz P&C's are very difficult to source used (I looked for almost 3 years), and very expensive new.

I have heard that these mods will make a very healthy engine with a higher redline, (maybe 30+ h.p.?) With a slight weight loss program and lower 2nd through 5th gears for my 915, it should be great fun, and the lower gearing should help offset the low rpm loss of torque.

I eventually want to go EFI, but I can't budget that right now. When my CIS is really in bad shape, I'll try to budget it - EFI with velocity stacks makes for a beautiful engine compartment...

[fred cook]

I did this last year for my SC coupe. I basically kept the 3.0 block, crank, oil pump and flywheel. Everything else was replaced. I spent 4-5 years gathering parts, looking for "deals" on prices. What I wound up with included: Mahle 100mm 10.1:1 pistons, LN Engineering slip fit cylinders, a nice set of Carrera twin plug heads, 964 cams, SSI exhausts, Electromotive XDi ignition and an early (78-79) large port CIS box and runners. Total cost for parts and a valve job on the used heads ran pretty close to $12k with all labor provided by myself. The end result is a very torquey, responsive engine that likes to rev. So far, I have only taken it to 7,000 rpms but it was still pulling quite well at that engine speed. The XDi system was fairly easy to install once I figured out where to mount the coils. By using the XDi system , I was able to eliminate the distributor which cleaned up the back of the engine and eliminated the future need for distributor caps and rotors. I chose to keep the CIS system to allow for easy starting and better fuel consumption. To help with tuning, I installed an Innovate air/fuel ratio gauge. Anyway, this should give you some thoughts on how you might want to do your rebuild.

[ridgebk995]

Did mine 4 months ago. Went 3.2 JE 9.5 Pistons, Webcam 465 Cams, SSI, M&K Rally muffler, Weber 40's, 915 gearbox--awesome result

[GT2BH]

Forgive the dumb question but if I go for 3.2 JE Pistons, what do I need to do with the cylinders and heads to make sure the car runs properly?

I'm going to read the re-ringing alusil thread later and see if that is my best option.

Did anybody not use a machine shop during their rebuild?

[LakeCleElum]

Originally Posted by G450X

I am facing a 3.0 rebuild also, this is what I'm planning.

98mm Max Moritz P&C's
Early SC (or Euro) heads, CIS, and distributor
964 cams
SSI's
M&K 2/1
Sachs power clutch with aluminum PP
Aluminum flywheel
915 with lower gearing

I have all the parts, I just need to have the used parts double checked for wear and have the heads rebuilt. The Max Moritz P&C's are very difficult to source used (I looked for almost 3 years), and very expensive new.

I have heard that these mods will make a very healthy engine with a higher redline, (maybe 30+ h.p.?) With a slight weight loss program and lower 2nd through 5th gears for my 915, it should be great fun, and the lower gearing should help offset the low rpm loss of torque.

I eventually want to go EFI, but I can't budget that right now. When my CIS is really in bad shape, I'll try to budget it - EFI with velocity stacks makes for a beautiful engine compartment...

I highly recommend the Max Moritz set-up. It's about the only way to run high compression and keep CIS. I have this engine in my 73.5:

1) Max Moritz 3.2 liter pistons and cylinders, 2) 964 cams, 3) Raceware hardware, balanced rods, Carrera oil pump. New parts included: intake valve sleeves, rod bearings and rods balanced, and rocker arms. Transmission clutch disk, pilot bearing and fork were replaced. 4) Early Exhaust. 5) Trombone oil cooler does a great job. 6) MSD

Have paperwork of Dyno run of 209 at the Wheels. Keeping the CIS saved a lot of money and retains good fuel mileage.

[al lkosmal]

https://www.youtube.com/watch?v=HcHt3raR5OM



regards,
al

[timmy2]

Aw C-mon Al, no text telling him it is a stock 3.0 that you went through and just cleaned up and made sure it was all ok and then bolted those beauties on there.
All steel studs even on that 3.0.
The story is here:
3.0 efi/mfi/itb


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[ridgebk995]

EBS did my cylinders and JE pistons and rings, quick and fairly priced as well

[fred cook]

Originally Posted by LakeCleElum

I highly recommend the Max Moritz set-up. It's about the only way to run high compression and keep CIS. I have this engine in my 73.5:

1) Max Moritz 3.2 liter pistons and cylinders, 2) 964 cams, 3) Raceware hardware, balanced rods, Carrera oil pump. New parts included: intake valve sleeves, rod bearings and rods balanced, and rocker arms. Transmission clutch disk, pilot bearing and fork were replaced. 4) Early Exhaust. 5) Trombone oil cooler does a great job. 6) MSD

Have paperwork of Dyno run of 209 at the Wheels. Keeping the CIS saved a lot of money and retains good fuel mileage.

Sounds a lot like my engine except that I used Mahle pistons and took it out to 3.3 liters instead of 3.2. I also used a set of big port twin plug Carrera heads and the large port CIS box and intake runners. So far, it is running great! Proof that CIS can make significant horsepower! Haven't done a dyno run yet, but that is on my short list of things to do.

[GT2BH]

If it came down to EITHER a 3.2 setup with CIS or a 3.0 setup with PMOs, what would you choose?

[timmy2]

PMO EFI or carbs?


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[fred cook]

3.2 w/cis!

[SCrescue]

Originally Posted by GT2BH

I've searched, I've read, and I'm more confused than when I started (probably due to lack of experience)

Carbs, EFI, CIS?
95mm 3.0 pistons/cylinders or 98mm 3.2 pistons/cylinders?
Stock cams, 964, custom?

Restrictions in the rebuild are as follows:
1) No pelicans near me to help out, which is a huge drawback
2) No machine shops which are specialized in Porsches
3) Parts should preferably be plug and play
4) I live far far away and shipping can get expensive

So basically I need to do this on my own, with minimal help from a machine shop. Budget is around $10k for parts. Car will be a weekend driver, spirited driving, weather ranges between 15c-45c, and we have no emissions restrictions. I can also run it on race gas if necessary since it won't be driven much.

You don't mention the current condition and configuration of your engine. How many miles on it? Does it need a complete split-the-case rebuild along with the desired upgrades? It's not clear to me from you post what your full intent is.

If you've not already done so, check your cylinders to determine if you have Alusils or Nikasils, that will be a major factor in deciding which way to go. If you have Mahle Nikasils, you should probably re-hone and re-ring them. a $10K budget will be eaten up quickly if you plunk down $4K to $5K for new P&C's.

New main & rod bearings alone are $500+, pressure fed tensioner kit is $600+, and on and on...you could easily blow $10K just doing a full rebuild.

And forget about race gas. If you exceed 9.5:1 compression you're going to need to go twin-plug, which will blow the crap out of your budget.

Not trying to talk you out of anything, just trying to inject some reality into your plans.

You can rebuild you motor and do upgrades within you budget if you approach it smartly. Understand what you have first and then you can make decisions on what you can accomplish wtihin your budget.

[LakeCleElum]

Originally Posted by fred cook

3.2 w/cis!

Agree - Luv how my CIS works with high compression 3.2. A budget option is always Zenith Tin-40's.....I've bought a few sets for $200 to $300 for my 2.2.

[GT2BH]

Originally Posted by SCrescue

You don't mention the current condition and configuration of your engine. How many miles on it? Does it need a complete split-the-case rebuild along with the desired upgrades? It's not clear to me from you post what your full intent is.

If you've not already done so, check your cylinders to determine if you have Alusils or Nikasils, that will be a major factor in deciding which way to go. If you have Mahle Nikasils, you should probably re-hone and re-ring them. a $10K budget will be eaten up quickly if you plunk down $4K to $5K for new P&C's.

New main & rod bearings alone are $500+, pressure fed tensioner kit is $600+, and on and on...you could easily blow $10K just doing a full rebuild.

And forget about race gas. If you exceed 9.5:1 compression you're going to need to go twin-plug, which will blow the crap out of your budget.

Not trying to talk you out of anything, just trying to inject some reality into your plans.

You can rebuild you motor and do upgrades within you budget if you approach it smartly. Understand what you have first and then you can make decisions on what you can accomplish wtihin your budget.

Sorry, I didn't link my teardown thread as it has more info - Newbie engine teardown/rebuild - advice always welcome!

The engine is already apart and in pretty good condition. 115k miles on the odo and I don't have full history. The cylinders are Alusil. My tensioners already have the oil line going to them, so I made the assumption they are already oil-fed.

I can increase my budget to $15k but I was keeping a buffer for shipping costs. Like I said, I don't have access to a machine shop that specializes in 911s, so I might send out my heads and rods to Steve@rennsport.

[GT2BH]

Originally Posted by timmy2

PMO EFI or carbs?


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sorry, carbs didn't even consider EFI yet

Originally Posted by fred cook

3.2 w/cis!

Originally Posted by LakeCleElum

Agree - Luv how my CIS works with high compression 3.2. A budget option is always Zenith Tin-40's.....I've bought a few sets for $200 to $300 for my 2.2.

Seems like 3.2 is a popular option! which combination pistons/cyl do you guys recommend?

[Steve@Rennsport]

Good question.

Several years ago, this would have been much easier to answer as CIS would have been my reply, however things have changed due to lack of new parts and the age/condition of current ones. The ethanol fuels we have simply accelerated the process.

Since Porsche & Bosch no longer support CIS, this is a major consideration.

If one has a CIS system that's in perfect condition, I'd strongly encourage that person to be very diligent about maintaining it so (hopefully) you don't need any new parts.

For performance applications, one just cannot beat a six-throttle intake system of choice, either PMO carbs or an ITB system with Engine Management. Single-throttle systems just don't even come close to offering that level of throttle response and power.