3.0 -> 3.?

[1980 911 sc]

Ok, i have a 3.0 and have some 3.2 cylinders coming that I will be getting opened to 98mm. If I find a 74mm crank, what else will I need to make a 3.4? Can i use my exsisting 3.0 liter rods?

This motor will be boosted, so what upgrades should I do to the case itself? shuffle pin? moon? boat tail? better squirters?

I was looking at a EBS advertisment. Are they good peeps? can they answer/recommend to me what should be done? Any one recommend thier personal favorite shop?

I want to do this rebuild myself, despite never having doen one before, that is why I bough tthis car!

[Carrera3.5L]

Hi,

Congratulations on getting bitten by the displacement bug! To make 3.2L from 3.0L, all you need is the 98mm pistons and cylinders with original size 22mm pins and your stock SC rods and SC 70.4mm crank.

If you want to go bigger, you will need a 3.2L crank (74.4mm) or 3.6L crank (76.4mm). The wrist pin diameter increased to 23mm on 3.2L applications so you will need the appropriate pistons to match. Depending on what displacement you decide on, you will also need to change to 3.2L rods or aftermarket (Carillo, Pauter). If you choose 3.4L, you simply will need the 74.4mm crank, 3.2L rods (or aftermarket equivalent) and 98mm pistons & cylinders with the 23mm wrist pin diameter.

Displacement all the way up to 3.7L is possible with your 3.0L case. It all depends on how much money you want to spend on parts and machine work to make it happen.

If you are further contemplating "boosting" your motor which I assume is forced induction of some sort, make sure you lower the compression ratio to suit.

Machine work is dependant on what you are trying to accomplish. Boattailing, shuffle pins, mooning the cylinders are all generally done on higher rpm race motors. Many will argue their merits on a street driven car below 7,000 rpm. For the record, I had all 3 done on my current 3.5L street motor build and I don't think I will see 7,000 rpm very often.

Good luck with your project!

Ralph

[1980 911 sc]

hmmm a 76.4mm crank will fit in a 3.0 case?

[rdane]

Jon at EBS is awesome. He walked me through and held my hand while having my 3.4 built from a '79 3.0. Love the engine.

I bought the ARP hardware, Mahle P&Cs , Pauter rods and a 74.4 crank from EBS. Jon went beyond the call of duty to see that everything was done right for me.

This motor will be boosted, so what upgrades should I do to the case itself? shuffle pin? moon? boat tail? better squirters?

Not many going to tell you to shuffle pin a 3.0 case I don't think. But I too did the rest of the mods mentioned (they are cheap while it is apart) on my 3.4 street engine and it rocks. I get anything out of that money? Doubt it on a NA engine.

If you are doing a turbo, pays to remember Yellow bird was a 3.4 98s with a 74.4 crank and twin turbos.

[Nitrometano]

What about the cylinder heads? Can be use the original 3.0 heads to make a 3.2 or 3.4 conversion or need to machining or buy a 3.2 or 3.4 cylinder heads?

[rdane]

You can use the 3.0 heads and decide what C/R you want to dial in after measuring the actual. 3.0 heads will give you 10.5 or better on a 3.2 to 3.4 set of Mahles with a 74.4 crank that would be 9.8:1 with 3.2 heads.

I had my heads milled to bring my compression back down to an actual 9.8:1.

[Carrera3.5L]

Originally posted by 1980 911 sc
hmmm a 76.4mm crank will fit in a 3.0 case?

Yep. You will also need to machine the 100mm piston tops that are generally used for 3.2L to 3.5L conversions but it can and has been done for many years. Will also need rods (stock 3.2L, Carillo or Pauter) for 23mm wrist pins. Case spigots have to be bored from 103mm to 105mm as well.

I've never seen or heard anyone using modified 98's with the 76.4mm 964 crank to make a long stroke 3.5L, I wonder if it has been done? Anyone know?

Ralph

[rdane]

I was told the long stroke 3.5 had been done and thought about it myself but the cranks are harder to come by. Little scary since there are few around. But last year this time there were very few 98, 3.2s or 3.4s here as well.

Now we have dyno info and a number of guys running 98s in 3.2s and 3.4s of all variations.

I am trying to decide how to rebuild a 3.2 motronic at the moment myself.

Gotta think the 3.5 long stroke would be a great engine as well.
Andial's moster 3.7 conversion is worth a look too. Bigger is always better

[Carrera3.5L]

Originally posted by rdane
I am trying to decide how to rebuild a 3.2 motronic at the moment myself.

Gotta think the 3.5 long stroke would be a great engine as well.
Andial's moster 3.7 conversion is worth a look too. Bigger is always better

And soon we'll have dyno info for a 3.5L Motronic as well and can determine if the extra expense (3.4 to 3.5) is really worth it.

I have the piston drawing to modify the 100mm piston generally used for 74.4mm cranks to make 3.5L into 3.6L (both normally aspirated and turbo version) using the 76.4mm 964 crank. Unfortunately, I don't have a drawing to do the same for 98's to make a long stroke 3.5L using the 76.4mm 964 crank.

Logically, you may assume that the Andial kit would just use bigger p's and c's and the 964 crank to make 3.7L but that isn't the case. The bore does increase to 102mm but the crank used is the 3.2L 74.4mm version, not the 964.

3.2>3.4 is 98mm P's and C's (no case machine work)
3.2>3.5 is 100mm P's and C's (with case machine work)
3.2>3.6 is modified 100mm P's and C's, 964 crank (with case machine work)
3.2>3.7 is 102mm P's and C's, 3.2L crank, aftermarket rods (with case machining)

The old saying is there is no substitute for cubic inches generally holds true, however the bigger the motor the more other factors come into play like twin-plugging and thermal limits. Bear in mind that 3.5L and 3.6L versions will have the case spigots opened up to 105mm from 103mm and this has been done for almost 20 years. For 3.7L, the case spigots have to be opened up even more (to 107mm). I don't know how many 3.7L conversions have been done, but it will be interesting to see if there are any long term reliability issues with a motor this big.

The 3.7L is attractive because it retains the 3.2L crank (lulling people into believing they can perhaps save some money), but I gotta believe that the 102mm piston and cylinders are REAL expensive and probably cost as much as 100's and a good used 3.6L crank would (or pretty close).

You will also need to twin-plug most of these bigger motor combos so that needs to be factored in as well. It would be real easy to spend 10K-12K just by purchasing the building block components and machine work and you haven't even gotten any of the normal rebuild parts or considered labor.

Here is an image of a 3.2L case that has been opened up from 103mm to 105mm for use of 100mm pistons and cylinders:



The price of machine work to do this is relatively insignificant in the big picture but for a 3.7L you will need to go 2mm larger. Will this be safe? Only time will tell I guess but I would think if Andial is the one developing this conversion then it probably is. They are usually very, very conservative with their offerings and claims and run prototype motors in Arnold's car for a good length of time.

I know Arnold put a good many miles on the very first 3.0L to 3.6L conversion that was done in the late '80's before the parts kit was released for sale.

Ralph

[Bill Verburg]

and the advantage of doing all this over starting w/ a 964 or 993 which has knock sensors and twin ignition stock would be.....?

[Porschekid962]

It's cooler more thats the difference. haha, who knows, why not, while i was in there, etc, etc.

[Carrera3.5L]

Originally posted by Bill Verburg
and the advantage of doing all this over starting w/ a 964 or 993 which has knock sensors and twin ignition stock would be.....?

Good point Bill. The newer motors have many advantages and should be considered. The wild card is cost and keeping your fingers crossed that the used 3.6L you bought will actually last 125K+. What's the point of transplanting a 3.6L with 50K-75K on the clock and then it needs to come apart 5K-10K later due to a problem? You're right back where you started. I saw just as many 3.6L heads at Ollie's being fitted for new guides as 3.0L and 3.2L heads. They have their share of issues as well. I can afford to do one rebuild and spend some money, but I couldn't afford to buy an expensive used 3.6L motor, not get much for my 3.2L core with bad guides and then potentially have to rebuild it again sooner rather then later.

Don't get me wrong, I would love a 3.6L Varioram with all of the bells and whistles and then tear it down and rebuild it for longevity. But I can't. I'm comfortable with the 3.5L conversion and the money I've spent.

Different strokes for different folks...

Ralph

[Bill Verburg]

What's the point of transplanting a 3.6L with 50K-75K on the clock and then it needs to come apart 5K-10K later due to a problem?

I agree and rebuilt my 993vram as a 993RS.

The end package is going to be superior when you start from a more advanced point. The total cost of a stock configuration rebuild will be much less than the cost of a custom configuration.

Last I looked the 993RSR p/c were actually cheaper than the earlier varients.

[Porschekid962]

Most transplanted 3.6's that I have seen here in socal are mostly stock, chip with modded exhaust or full blown street race engines with a little more reliability than a race motor. I guess if your going to buy a 3.6 and take it apart slightly to ensure reliability wouldnt it be a better bet with a 964 3.6 since it would be cheaper to buy?

Eh im just full of hot air today it seems. Back to work for me.

[1980 911 sc]

my intentions are:

to take my 1980 3.0 and open up the 3.2cylinders I just bought to 98mm. I am concidering getting the larger crank and high end rods, but I ESTIMATE an additional 4K in costs to do this. I think I have decided if I open the case and the crank is bad I will go larger, else stay with the one I have.

I plan on adding a supercharger to this motor, and hopefully UMSII if it comes out buy next winter. So what do I gain out of rebuilding my old motor?

a) a complete fresh rebuild
b) a hot rod porshce, I made myself
c) headaches, from hearing the wife whine about whatever I decide to spend OUR money on in this car... I am claiming I am undergoing a 3 year long midlife crisis, cause that is how long this is gonna take me...

[Porschekid962]

UMSII whats that? The more and more I think about it and start pricing things out it would just be easier to put a stock 3.2 in the back or possibly a 3.6 and do a top end job on that instead of tearing down a 3.0 and building it up.

What kind of supercharger are you thinking, belt drive or electric?

[Superman]

I would expect that a 3.6 transplant would be the best bang for the buck. And if the worst happens and you need to freshen it 50K later, then fine. Open her up, replace some parts, zip up and away you go.

Sometimes I wonder whether there are just two NA flat six engines that make sense to build (except for purpose-built race engines) They would include the 2.7 RS, complete with MFI, and the 3.6 or 3.8.

[Porschekid962]

I think the 2.8 MFI engine would be on my list or a tricked out 3.5. From what I have heard the 3.8 is rather costly and the gain is not that dramatic. A well done 3.6 with ITB's would be nice too!

[1980 911 sc]

UMSII = Ultramegasquirt, it was a typo. I have an Eaton M90 and TB from a 3.8 ford Tbird.

Page 108 of wayne,s how to rebuild and modify book is what I want...I can't sleep when I am thinking of it...

[rdane]

"Sometimes I wonder whether there are just two NA flat six engines that make sense to build.."


Just glad it is the engineers @ Porsche who decided such things and not you Jim