Classic 3.0 motor build?
 

I have acquired a core 79 SC motor, 930/13. tore it down to a long block yesterday and got it on the stand. From a basic visual inspection standpoint, case has been split in the past, 2 head studs have been replaced. I was going to just bolt on some early exchangers and Webers, but seeing as the case has been split, the amount of red gasket material on the exhaust and Alumablast on top of the case, have decided to make it a full tear down, inspect and build back up over the winter.

it's going into the 73T so I'm looking for an honest 200 to 240 (at the very most) hp.

Is there a basic spec to achieve this goal, one that's been built many times, tested and time-honored?

P/C and matching cams? I've got early exchangers, will go with new PMOs, and complete it with a M&K single out.

A friend of mine who has done 4 motors (and they still run) is managing the build and I'm more of the grunt work, parts running, cleaning, acquisition.

Given the vast experience here, are they any must-do's and tricks "while I'm in there?"


Tailgate on the 4Runner makes for a great workbench.

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You might want to invest in an engine stand and yoke.... the "tailgate" method of engine rebuilding has its drawbacks ... :-)

Thanks Jim, yes, it's mounted on a stand and yoke now at my friend's house. I think we'll be tearing it apart next weekend.

If you are doing P&C's + cams anyways you might as well build a 3.2SS out of it. well known config. See P. 113 of Waynes book: start with a 3.0, get 98mm P/C's, 46 carbs, GE80 cam, twin plug heads, and BOOM There it is!

Wish I was building this car ;(

-Michael

+10 on the 3.2SS! But one comment to euro911sc - never ever use the word BOOM in an engine rebuild thread!

JB

LOL sooo right JB!

Here are a few routes that are generally accepted. They are ranked from cheapest (buy fewest parts) to most expensive. I would think that an early street/touring setup would favor the first or second one. Each example has its own documentation in the archives.

1) Keep SC 8.5:1 pistons and add 964 cams. Will extend rpm range a bit higher. Proven combination. Runs on Pump gas (cheap gas). Good low rpm torque.

2) Stock pistons and custom cam. Can maximize compression ratio and valve clearance for CIS pistons. Better performance than 1). Check with John_D about the possibilities. Mention you will run carbs. He can set overlap and exhaust lift to maximize induction.

3) JE pistons and Mod-S cam. Keep compression around 9.3 to run premium pump gas. Could go slightly higher at the expense of timing advance in summer. The NE might not be a problem. Benefit is large valve pockets. Cam upgrade for future track work is easy - no teardown.

4) 3.2SS. Expensive but worth it. Usually requires head mods (chamfer, twin-plug) and all the fun goodies. Can generally take as much cam as you want to throw at it. Make sure the oiling system is up to par if you want to run high rpm.

The road to the perfect engine has many paths. Each has its own destination depending on what you want out of the car and how much you want to spend.

Why on earth would one recommend GE80 camshafts for a street 3.0 build?
What a waste that would be, not to mention a very dissapointed owner.

I have a hotrodded 3.4 engine and Webcam 120/104 cams(similar to GE60), with PMO carbs,
and it is just streetable - doesnt pull hard until 4500 rpm.

I agree with the Mod-S cams ( at the most )

Just my thoughts.

Your goals are easily attainable. Carbs, SSIs, Sport muffler: 220 plus HP. Carbs, 1 5/8 headers w/race muffler, Euro pistons or JE 9.8: 240 plus HP. These are configurations based on tested Spec 911 motors (note 1 5/8 headers and JE pistons are not Spec 911 legal, but we have tested them).

-Andy

Thank you for all the replies so far, much appreciated. the 3.2SS is way out of budget so I won't be going in that direction. I have friends in Europe looking for good used 9.8s at a good price for me so I will go in that direction.

Any thoughts on a cam to match them?

I would not recommend anything higher than the 9.3 pistons. If single plug, I doubt you would feel the seat of the pants difference between the two compression ratios. A high percentage of 9.8 owners experience broken rings at the minimum and a very compromised ignition curve. I would recommend an octane booster if someone is stubborn enough to go this route.

If you are planning to go twin plug, then by all means 9.8's are fineSmileWavy.

My engine is a '79 3.0. I rebuilt 3 years ago. The engine now has 30,000+ miles on it. I used the JE 9.5:1 pistons, 964 cams, SSIs and a two out Monty. I dynoed it last November and got 187 at the wheels.
Just a little info to help with your decision.

Aaron, got your email, thank you for responding to my inquiry. I already have the MSD so I'm a little ways there if I go twin. Going to see what turns up in the way of P/C which will really determine my path. The distributor is the one thing that hits rev limiter on the budget, but I've got all winter to pull the math together on that. Scope creep is a terrible thing. :)

Kevin, sounds like a great motor. Can you add some subjective experience, what you like, what you don't like, how's it feel, how fast does it feel, etc. Did you stay with CIS?

Ain't that the truth! BTDT.

I did keep the CIS. I really am pleased with the power. The power band is strongest from 4000 to 5500. Doesnt fall off above that but no real need to rev above this point, although I have tested the rev limiter on many occassions. I am still very pleased with the results.
I just added MSD this weekend. So far it just seems to smooth everything out. Wasn't expecting anything more than that.

Thanks Kevin.

Aaron and others. I've located a set of new "Mahle motorsport 3.0 litre pistons which they supply for the RSR, we cc'd a piston and it came out to 9.7.1:1 with a 1mm head clearance in a 89.5 cc volume head. We wanted the original 'werks' compression ratio of 10.3:1 so have
gone with a different non mahle solution so the set are spare.

These pistons are new, still in their wrappers and packaging and ready to go with the rings, pins and clips."



My (extremely limited) understanding is that mixing piston sets and cylinder sets (I still need to determine if mine are good BTW) is not a plug and play affair.

can anyone please comment? thank you!

EDIT: So many here say to stay away from JE's for a street motor, but should I just go for JE 9.5s?

Verify that the wrist pin size of the new pistons will work with your rods.

Your jugs are probably Alusil, that just seems to be the luck of the draw. In which case, no, you can't put new Mahle pistons in them. You might get Nikasil jugs, but they'll have some wear. If using new Mahle pistons, I don't think I'd be able to live with myself if I didn't match them up with a set of re-plated cylinders. Just send yours to EBS and they'll do it. Doesn't matter if you send them Nikasils or Alusils.

JE is supposed to have a new alloy that finally 'works' on the air-cooled motors. However, I haven't heard any data coming back on these yet. Call around to the big shops and ask, if that interests you.

Another option is a set of QSC pistons/cylinders from Henry @ Supertec.

When I needed to match 1 9.8 euro SC piston to a cyl I already had it was a pain in the ass. I had to match the weight group for the pistons and then the diameter group for the cyl I needed to use. If you are buying new stuff or mismatched stuff just measure the hell out of the clearances and make sure it works with in spec. and you will be fine.

I run 9.8:1 CIS on pump gas all day long... however, I did blow the ring landings off a piston 3 years ago... resulting in see above ;)

BTW, I'm not recommending GE80 cams, just stated whats in the book ;)

-Michael

Thanks guys, again, I hope to split the case with my friend Chris this weekend. Probably getting a little ahead of myself, certainly way ahead of my wallet. What we find this weekend will surely help set direction. Look for pics.

Subscribing.

Good luck with the build, Shaun.

Shaun, give me a call and I will give you a verbal download on Jeff Higgins motor. Simple to build and everything you ever wanted.

Kenik, I'm sorry, I just saw your post. I'll give you a call tomorrow.

Thanks Ed, good to see you.SmileWavy

We had a very good day taking the motor down, mostly good, maybe a little bad. I'll post pics tomorrow.

Want to get advice on these pistons. I can get them for just a little more than JE's so I must consider them. Is there a specific motor I should be building with forged Mahle motorsport 3.0RSR pistons? What do they need in terms of induction? Reason I ask is that I got the motor in the 73, the mystery 69T case with Webers to run beautifully on Saturday. it's a strong little motor whatever it is, and the carbs are running like motronic...warm anyway...turn the key standing outside the car and it starts right up and idles smoothly. That means instead of considering PMOs for this build, I'd be smarter to just rejet my Webers. My question is will these 40s be up to the task for these pistons and proper cams? Also, is it as easy as sending my cylinders to EBS to be replated to match these?

Thanks so much for the help. I hope it's not too abundantly clear that I have virtually no knowledge about building motors, but I am eager to learn.:D

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The Mahle's should get you about 9.7-1 with SC heads (IIRC). They are a very nice piston with good valve pockets.

Buy the Mahles - those are really, really nice.

Given the data here, these are mighty small, but I assume EBS can replate my cylinders to match?

Question: wrist pin size. How can I confirm if these will match up to my rods?

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Shaun

I used those same pistons with new matching Mahle 95mm cylinders in my 3,0 RSR clone motor.

http://forums.pelicanparts.com/porsche-911-technical-forum/246563-another-rsr-clone-project-dyno-day.html

Not cheap to build but runs great on both steet and track.

Let me know if you'd like more detail.

Tom, your motor is quite an inspiration! Just wow!

After talking with Kenik (thanks!) and then a lot of back and forth with Jeff Higgins, I'm going to build a carb'd version of Jeff's motor. I still have some questions that need answers to but I should be underway in a week or two.

3.0 case
My Nikasil cylinders matched up with the 3.0 RSR pistons by EBS
My CIS heads refinished and twin-plugged by Anchor Atlantic
question: Aaron calc'd the CR at 9.7:1 above using my heads with these pistons. How can I increase CR? Jeff cautioned me about mixing these pistons with late heads and getting a low CR btw.
John Dougherty GT2-102 cams, also his sport springs on the heads
Spark from either Aaron's distributor set-up or Electromotive
Weber 40 IDAs
Early heat exchangers
M&K 2-1 muffler

What am I missing? Thoughts on specs?

This sounds like fun. Glad I subscribed. Those pistons are quite a find.

Engine Build
 

Shaun,
From what source will you get the twin plug distributor?
Thanks
Tom

Tom, Burn Bros. (Aaron) up above a few posts makes them and they are arguably the best solution for twin-plugging these days.

Twin Plug Distributor
 

Good to know. November Excellence magazine has a write-up on a gorgeous Tour de France 911 and in the article they mention Burn Bros in Fallbrook, CA as the source for the twin plug distributor. I was unable to locate a business by this name in Fallbrook. Now I know.

Good luck with your build.

Tom

Shaun

you can have the heads fly cut to reduce the chamber volume for the stock number of 90 ml to 84ml.

This will give a CR of 10.5:1

http://forums.pelicanparts.com/911-engine-rebuilding-forum/213504-whats-your-head-volume.html?perpage=20&pagenumber=1

Weber 40's will be too small if you run the right cam and have the ports opened up. You need 46's.

Agree w/above, if you're twin plugging, then get the compression high enough to make it worth it.

Not sure why you want to ship stuff to multiple shops, I'd just send it all to EBS. They did my last set of heads, best work I've ever had. Really excellent documentation of work performed & measurements taken came with the heads, too.

I hope my stream of consciousness, evolutionary posting isn't annoying. It's just what it is, going through the motions of building a great motor while learning about all the options and getting a lot of professional, sometimes obliquely conflicting information. I was talking with Don RE: matching the P/C (he's been great) and he won't be able to give me a firm answer on CR until he has them in hand. he noted that if CR works out to 9.8:1, I should just stay with single plug and 93 gas. So if I am on a budget, should I sacrifice some hp and stay single plug, keep heads as is and maybe a year or 2 go all out or do I go all out now. Many many options and making one selection effects the next assembly and so on. Sure, with $10K, I could just spec it out pretty fast. But I need to balance budget and assets on-hand against the final hp reward.

engine teardown pics next.

OK, some comments on the CR business.

What is high enough? Steve Weiner preaches that anything 9.5:1 and higher can significantly benefit from twin plugs due to the fact that you can dial in an ideal ignition curve. He feels that Porsche motors on pump gas should stick to no higher than a measured 10:1 CR with twin plugs. His assertion is that anything higher is robbing Peter to pay Paul in terms of the fact that you will have to dial back ignition timing to accomodate the higher CR.

I am perplexed as to how compression goes up from flycutting heads when you have to back the head out the same amount you machined off to get your deck height back to 1mm. That is unless you machine your piston crowns, too.

Very true.

You do not back down your deck since deck has not changed.(you have not machined the cylinder as this would effect deck!)

Ah - sooooooooooo...

Then as long as you don't have interference issues between the piston crown and cylinder dome, you are good to go then. Nice to know. Well that and making sure your cam chains still work without too much slack.

Teardown pics.

Hmmmm
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Most of the barrel nuts were on "wrist" tight.
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My camera sucks. Should show good crosshatching. Magnet was sticky.
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Need a little welding/filling here.
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few more, I'm getting ready to pull all the studs and start cleaning next week before having it decked.

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Hey Shaun I have a great tool kit you can borrow. :-)
Frank