1978 3.0l SC - 100mm Bore

[Pork Chops]

Hi, I'm starting my research for an engine rebuild and assumed I'd do the usual 3.2SS conversion. I note however you can buy 100mm kits from LN Engineering ($$$$). I've also found an ebay seller with a 100mm kit that contains Mahle cylinders and JE pistons, noting the cylinders are plated (presumeably Nikasil) by Millennium Cylinders.

So my questions are:

1. Has anyone done this type of build? If so how'd it go?
2. What case modifications were needed to accommodate the cylinders?
3. How did the build go? Any hitches or issues?
4. How was the end result? Nice engine?
5. If all good can you recommend a reputable seller in the US that is not LN, or LN pricing?

Many thanks and apologies if this has been covered before. If so point me in the direction of the thread.

[KTL]

That's a 3.3L short stroke and you typically have to machine the engine case bores to allow the larger cylinders to fit into the case.

Member fred cook here on the forums did a nice job documenting how he built his 3.3 SS. He used a nice combination of parts to pull it all together as a comprehensive build.

One of the nice things about LN, even though it appears you're not too keen on their pricing, is they offer the 100mm cylinders as a slip-fit install which means you don't need to machine the case. The reason they can do this is because their Nickies cylinders are forged billet and stronger than the OEM cast Porsche cylinders. Since they're stronger they can withstand being a thinner cross section that allows them to slip fit the original size case bore.

[Pork Chops]

Originally Posted by KTL

That's a 3.3L short stroke and you typically have to machine the engine case bores to allow the larger cylinders to fit into the case.

Member fred cook here on the forums did a nice job documenting how he built his 3.3 SS. He used a nice combination of parts to pull it all together as a comprehensive build.

One of the nice things about LN, even though it appears you're not too keen on their pricing, is they offer the 100mm cylinders as a slip-fit install which means you don't need to machine the case. The reason they can do this is because their Nickies cylinders are forged billet and stronger than the OEM cast Porsche cylinders. Since they're stronger they can withstand being a thinner cross section that allows them to slip fit the original size case bore.

Thanks that was helpful. I think the issue for me will be finding the sweet spot for cost / benefit taking into account diminishing returns, and my real needs I.e. This is no race car. The other limitation is working within the CIS as modifying this along with everything else that needs to be done will take the budget too far. Perhaps 98mm, a hotter cam, 10+ comp ratio, and balancing the rotating assembly would be a good place to be for a peppy free spinning engine...But those PMOs sure look sexy...

[KTL]

I think Fred's approach was a good one, using the larger bore plenum and runner tubes from the '78 and '79 3.0L. Since you've already got those intake parts, along with larger bore heads (but not as large ports as the 3.2L Carrera heads that I believe Fred used) you're started off in a good place.

98mm vs. 100mm is really a non-issue since the cost difference between 98 vs 100 pistons and cylinders is virtually nothing. The freer spinning engine is going to be the one with lesser reciprocating mass. Get yourself a set of 95mm high compression pistons and continue using your existing cylinders? A good bit of power can be gotten from a 3.0L.

Definitely balance the rotating assembly. Get your crank, rods and pistons all weight-matched. It's cheap in the grand plan of everything.

PMOs are indeed nice. They let you tune to your desire just by changing jets. Problem is you need to have a selection of jets to dial it in. Can get expensive when you have to buy numerous sets. If you decide to go with PMO, make sure you heed the recommendation from PMO. They recommend size 46 PMOs when going above 3.0L street engine displacement.

[Pork Chops]

Originally Posted by KTL

I think Fred's approach was a good one, using the larger bore plenum and runner tubes from the '78 and '79 3.0L. Since you've already got those intake parts, along with larger bore heads (but not as large ports as the 3.2L Carrera heads that I believe Fred used) you're started off in a good place.

98mm vs. 100mm is really a non-issue since the cost difference between 98 vs 100 pistons and cylinders is virtually nothing. The freer spinning engine is going to be the one with lesser reciprocating mass. Get yourself a set of 95mm high compression pistons and continue using your existing cylinders? A good bit of power can be gotten from a 3.0L.

Definitely balance the rotating assembly. Get your crank, rods and pistons all weight-matched. It's cheap in the grand plan of everything.

PMOs are indeed nice. They let you tune to your desire just by changing jets. Problem is you need to have a selection of jets to dial it in. Can get expensive when you have to buy numerous sets. If you decide to go with PMO, make sure you heed the recommendation from PMO. They recommend size 46 PMOs when going above 3.0L street engine displacement.

I believe my cylinders are Alusil so can't be re-used. So I'm up for a set of pistons and cylinders either way, so I guess it's a matter of whether the extra displacement will add anything by way of power and torque, or as you say add weight to the rotating mass. Then there is cost...Seeing as I'm here asking questions what ignition system would typically be used with PMS carbs, given the car has the CIS system? Thanks.

[Tom_in_NH]

I believe you can have your Alusil cylinders plated by EBS.

Tom

[KTL]

Yep Tom is right. You can have your Alusil cylinders stripped & plated with nikasil by EBS (or send them direct to Millenium or US Chrome if you know your bore & clearance specs) to put in a set of high compression 95mm pistons of your choice.

The displacement increase certainly adds more rotating mass. But you still gain more power as a result of that bore increase.

Regarding cost, for a hotted up street engine, you can have your SC rods, which are good solid rods, checked for C-C length, balanced & weight matched, install ARP rod bolts. They're really good rods that are plenty up to the task for the occasional blast up to 7000 rpm.

The ignition system that a lot of people have chosen to use is RSR-style Burnham Performance (made from converting an original SC distributor) or JB Racing 12 plug single distributor with twin MSD 6AL ignition boxes.

JB Racing - Porsche Engine Components

Or you can use the crankfire style that Electromotive makes. The more modern XDi system with a remote ECU and "dumb" coils is better than the older all-in-one HPX ignition (ECU built into the board holding the dumb coils) that have been around since the early 1990s

Nowadays people are finding ways to implement even more modern ignition systems that pirate parts from Ford edis and Toyota coil-on-plug systems.

[Pork Chops]

Thank you again Kevin. I've just read up more on the LM Nickies and they do a good job of selling themselves. The question I have is how much do I care about some of their features such as:

• Forged, therefore run cooler. Are my 1978 Alusil cylinders forged or cast and how much do I care about this on a street engine?
• Half mooning for lower windage losses
• Stronger, more ductile etc. Well how strong do I need them to be? And yes I get that they can use a thinner wall and therefore increase bore size more easily, but do I need stronger?
• More cooling fins...Is this is the case on a 1978 cylinder or only on earlier ones?

I'm happy(ish) to pay for features that result in tangible benefits and outcomes but not for marketing hyperbole that doesn't make any difference in the real world.

If the benefits are real then maybe the Nickies are a good option and I just limit the build to oversized pistons (higher comp) and cylinders, get it all balanced, use stock cams and keep the CIS system (as well as a bottom end tidy up). That way the base of the engine is sound and if I want to add fruit such as PMOs etc later on then I can do so knowing the core building blocks of the engine are right.

If not maybe it's a matter of using refurbed 3.2 cylinders and high comp 98mm pistons and save the $$.

Sorry if I'm swinging around a bit with my ideas but I'm trying to figure it out so bear with me!

[Flieger]

The LN's alloy is matched for JE pistons, the theory being you shouldn't have problems with piston slap when cold, as would be possible with JE pistons in Mahle barrels.

[Pork Chops]

Originally Posted by Flieger

The LN's alloy is matched for JE pistons, the theory being you shouldn't have problems with piston slap when cold, as would be possible with JE pistons in Mahle barrels.

OK, but that's not a benefit. I can just as easily get Mahle pistons that work well in 3.2 barrels. Why is a JE piston in a LN cylinder any better, other than it's better than using an incorrect piston in the LN cylinder, or a JE piston in any other cylinder due to its greater expansion rate?

I'd like to keep this focussed on the real world, tangible benefits of the LN offering in my stated application (sweet street engine), as it comes at a price premium.

[3literpwr]

I recently built a high comp 3.0 and pondered if I should up the CC. In the end, I decided to have my stock cyls replated by ebs for around $850 and new 10.8:1 Pistons from JE (fsr style). I wanted to ditch cis and run a decent cam.

[Pork Chops]

Originally Posted by 3literpwr

I recently built a high comp 3.0 and pondered if I should up the CC. In the end, I decided to have my stock cyls replated by ebs for around $850 and new 10.8:1 Pistons from JE (fsr style). I wanted to ditch cis and run a decent cam.

Thanks for sharing. So you focused your efforts and budget on the PMOs, rather than expensive cylinders and pistons? Are you happy with the result? Any videos of the engine running in the car. Ideally at max revs!

[3literpwr]

Yes, I decided that the throttle response and cam options would out weigh the extra cc. Granted, PMO's are pricey @ 5k but so are nickies. No vids yet.

[Pork Chops]

Originally Posted by 3literpwr

Yes, I decided that the throttle response and cam options would out weigh the extra cc. Granted, PMO's are pricey @ 5k but so are nickies. No vids yet.

Yes well you've gone to the heart of the matter and that is in the end you must decide where you're going to spend your dough to get best bang for buck. I quite like your approach as all that money on cylinders you'll never see and in my application will have relatively limited benefit. Happy to be corrected. I guess with the PMOs you get great looks, something different / old school with carbs, better throttle response and sound.

Are you happy with your decisions and is there anything you'd change if you had your time again?

[3literpwr]

Sent you a PM with my engine build costs and other info.

[KTL]

Originally Posted by Pork Chops

Thank you again Kevin. I've just read up more on the LM Nickies and they do a good job of selling themselves. The question I have is how much do I care about some of their features such as:

• Forged, therefore run cooler. Are my 1978 Alusil cylinders forged or cast and how much do I care about this on a street engine?
• Half mooning for lower windage losses
• Stronger, more ductile etc. Well how strong do I need them to be? And yes I get that they can use a thinner wall and therefore increase bore size more easily, but do I need stronger?
• More cooling fins...Is this is the case on a 1978 cylinder or only on earlier ones?

I'm happy(ish) to pay for features that result in tangible benefits and outcomes but not for marketing hyperbole that doesn't make any difference in the real world.

If the benefits are real then maybe the Nickies are a good option and I just limit the build to oversized pistons (higher comp) and cylinders, get it all balanced, use stock cams and keep the CIS system (as well as a bottom end tidy up). That way the base of the engine is sound and if I want to add fruit such as PMOs etc later on then I can do so knowing the core building blocks of the engine are right.

If not maybe it's a matter of using refurbed 3.2 cylinders and high comp 98mm pistons and save the $$.

Sorry if I'm swinging around a bit with my ideas but I'm trying to figure it out so bear with me!

Sorry for the late reply.

The LN cylinders being forged primarily makes them stronger. The Mahle and Kolbenschmidt (KS) cylinders are cast. The LN cylinders also have more cooling fins than all of the variations of original Porsche cylinders. This is possible because the LN cylinders are machined from billet alloy and that allows them to machine in more cooling fins and make them thinner. This is nice since the air cooled engines can use as much cooling as we can get for them.

On a street engine? Probably not a big feature to tout. The original cylinders have survived this long being cast and having less cooling fins. Mahle continues to produce them with the same design. So they're sufficient for sure.

Mooning the cylinders is a lot like boat-tailing the engine case bearing supports. The gains are minor.

I think the LN benefits are noteworthy, since why not optimize the cylinders when starting from new. But relatively speaking, these benefit are realized the most in an engine that is highly stressed like a dedicated racing engine that's run at high rpms almost exclusively.

You have to be careful with your piston choice in the sense that you want them to agree with your camshafts and induction. If you go high compression pistons and use stock cams & CIS, you're foregoing considerable added power. Power doesn't come cheap in these engines whatsoever. Then you come along later and install PMOs, you've got cams that are less than ideal for individual throttle body carburetor induction.

I would gather funds over time so you can get the complementary pistons, camshafts and induction so that it all works as a system from the very beginning. Honestly I feel the cylinders are the least of the important pieces in terms of building the engine for what you want it to do- build revs better and make some more power.

Bored & plated 3.2 cylinders is not a bad way to go. It works. You're simply limited to a 98mm size because you can't bore the cast cylinders any more than that or else the base spigot gets too thin. JE pistons can be used with them no problem. JE's piston metallurgy is such that the engine builders who have done this before have figured out that we need 0.0015" of skirt clearance for the JE + Porsche original cylinder combination.

I'd also recommend you have your rods reconditioned and fitted with ARP rod bolts. The SC rods are a good strong rod to use for a warmed up street build.

All sorts of questions come up about how to configure these engines. There's quite a lot of ways to create them from various parts combinations!

[Pork Chops]

Thanks Kevin a detailed and concise reply as always.

Nickies sound ace but not for me as too much money for no real benefit.

I've contacted EBS and Steve Weiner for info on pistons, cylinders and PMOs as pricing in Australia is often a little OTT. That said there is a good local guy I'm talking to. I can get a 3.2 crank and rods and with 98mm pistons that will be giving me a 3.4, but at considerable additional expense over the 3.2SS and a 3.0. I'm fairly certain I'm going PMOs, high comp pistons and a suitable cam, so as you say Kevin all of those things are now fairly resolved. It's just a matter of how much capacity I'm prepared to pay for and understanding any hidden downsides of going bigger. I.e. You can't spin a 3.2 crank as hard as a 3.0 and you've got more rotating mass.

Any thoughts on the extra capacity versus cost would be great. 3literpwr why did you 'just' stick to 3.0?

Lastly what is the general consensus on oil pumps. Do you leave them standard, refurb or modify, or get a 3.2 or GT3 pump? Another area I'm sure I can drop a whole lot of $$!

Cheers.

[snbush67]

Why high compression? Consider the longevity, lower cost and the simplicity of lower compression.

[Pork Chops]

Originally Posted by snbush67

Why high compression? Consider the longevity, lower cost and the simplicity of lower compression.

What are you running, why, and with what results? Interested to hear.

[snbush67]

I'm running 78SC Big Port 3.2 SS, 46 PMO Carbs, M&K 2/2, RARLYL8 Headers, DRC GT2-108 Cams, MSD, Clewett Wires, J&E 98mm.

Why?...I don't really know, I pulled my motor to fix some leaks and a few months later I ended up with way more motor than I needed.

Here is the thread in which this forum helped shape my build;

Shanes 3.2 SS - Recommendations and Advice