3.5 verse 3.6 conversion on a 80Sc

[ARCSinAK]

Gentleman-
Any thoughts about taking your stock 3.0 case and modifying it to 3.4, 3.5, 3.2ss ect verse going through the 3.6 conversion process? The way I see it its almost like six of one half dozen of the other.

Which way do you go? 8g's for a 964 3.6 with unknown history and 95 thousand miles, which may need gaskets or a re-fresh. 10 G's for a nice 933 vario, in addition to another +/- 6 grand in conversion parts for either 3.6 part like harness dme, engine tins, fly wheel, ect.

If your going to spend 16G would you rather build and bad ass 3.5 from the ground up or play the 3.6 game??

[JP911]

Tough question. You're looking at it from the right perspective -- used and unknown vs. fresh build. The 3.6 will be cheaper in the short term, but the long term is an unknown. That said, a bad ass 3.5 is going to cost more than $16K. If you do the work yourself you might keep it under $20K. Pay a skilled Porsche mechanic and you're looking at something closer to $40K.

[KTL]

It's not uncommon for 3.6 conversions end up in rebuild mode. If you've got a good SC engine to start with (heads are already good/don't need reconditioning, you've already got carbs, already have suitable headers) you can end up with a good 3.3L engine with some nice power. But it'll still come up short on TQ and HP to a good 3.6

Lots of options for a 3.0L you can go for displacement or rpms. Ported heads, matched cams, right induction and you can get 300 crank hp out of it. Building a 3.6 gets much more expensive.

A lot also depends on how you plan to use it.

[Bill Verburg]

The 3.6 is going to be worth a lot of extra cash to most buyers. It is a lot more than just a few extra ccs
you get

1. a motor designed from the ground up to put out 270-300 reliable hp w/o any fuss
2. ceramic inserts in the heads that keep head temps under control
3. the 993s have much bigger ports valves and are made from RR 530 heat resistant alloys, only 930 small port heads previously used this alloy
4. knock control
5. sophisticated engine management, tunable in the 55pin versions
6. decent exhaust is usually included in the 993 versions
7. oil filter on both inlet and outlet sides of the oil system in 993 versions
8. variable intake that increases midrange torque/hp

[don gilbert]

what Bill said. I always though i wanted to build something a little more exotic out of 3.0, but now that im older and smarter, just cant justify the 20g of cash flying out of my pocket for a morfidite engine. ( i have 9g in a 3.0 build, and thats doing all the work my self.) Im going 3.6 on the next one.

[KTL]

Originally Posted by Bill Verburg

The 3.6 is going to be worth a lot of extra cash to most buyers. It is a lot more than just a few extra ccs
you get

1. a motor designed from the ground up to put out 270-300 reliable hp w/o any fuss
2. ceramic inserts in the heads that keep head temps under control
3. the 993s have much bigger ports valves and are made from RR 350 heat resistant alloys, only 930 small port heads previously used this alloy
4. knock control
5. sophisticated engine management, tunable in the 55pin versions
6. decent exhaust is usually included in the 993 versions
7. oil filter on both inlet and outlet sides of the oil system in 993 versions
8. variable intake that increases midrange torque/hp

Fixed it for ya.

All very good points by Bill as always. Another plus for the 3.6 is the improved chain routing and chain tensioning. Porsche really made a nice improvement in the chain support ramps and chain tensioning system in the 3.6. May not seem like a big deal to most, but it's a big improvement in reliability. Porsche did away with the Carrera tensioners, tensioner oil supply lines, cam feed lines and made the pressure supply to the tensioning all internal to the engine and chain boxes. No more external lines to potentially leak.

[uwanna]

Originally Posted by Bill Verburg

The 3.6 is going to be worth a lot of extra cash to most buyers. It is a lot more than just a few extra ccs
you get

1. a motor designed from the ground up to put out 270-300 reliable hp w/o any fuss
2. ceramic inserts in the heads that keep head temps under control
3. the 993s have much bigger ports valves and are made from RR 530 heat resistant alloys, only 930 small port heads previously used this alloy
4. knock control
5. sophisticated engine management, tunable in the 55pin versions
6. decent exhaust is usually included in the 993 versions
7. oil filter on both inlet and outlet sides of the oil system in 993 versions
8. variable intake that increases midrange torque/hp

Also, due to the knock sensors and twin plugs, the compression ratio on the 3.6 is boosted to 11.3 vs 9.5 for a 3.2. Makes a 3.6 much more thermally efficient i.e better gas mileage and power. An older 3.0 motor would be a preignition nightmare at that compression ratio, unless you have a good cheap source of 100+ octane aviation gas!!

[racer]

Sell the carrera, take the 15K for the 3.6 conversion.. combine and buy a high mileage 996TT

[ARCSinAK]

I sure appreciate all of your comments.

[JeremyD]

It's a lot of money to do the conversion. It's a lot more money if you have to do the conversion AND rebuild the engine...

BUT - a 3.6 in an earlier car really scoots...

[Rodsrsr]

Just turbo it and you'll walk 3.6's

[JeremyD]

Or an LS 3 conversion.

Probably a turbo or LS conversions would not treat a 915 well (woops, there goes another expense)

Seriously - I've done both = built up a 3.4 993ss cam'd engine out a 3.2 (287 hp thank you very much) And now I've done a 3.6 conversion (and rebuilt a 3.6 heads, new P & C's, cams)

I really think that for all the $$$ I've forked over I might be inclined to fork over the money for a lower mileage (or rebuilt on someone elses $$) later car (964 or 993) and go with the whole car that's been built from the ground up with those systems in place.

964 and 993 both have engines, cooling systems, brakes, transmissions, suspension designed for each other. Probably where you could get the real performance increases is by reducing weight -

Just from someone who has been there, done that and got the T-shirt

(although it is nice to have a cooler older car that goes like a bat out of hell)

[KTL]

Originally Posted by uwanna

Also, due to the knock sensors and twin plugs, the compression ratio on the 3.6 is boosted to 11.3 vs 9.5 for a 3.2. Makes a 3.6 much more thermally efficient i.e better gas mileage and power. An older 3.0 motor would be a preignition nightmare at that compression ratio, unless you have a good cheap source of 100+ octane aviation gas!!

You can run a twin plug 3.0-based engine at 10.5:1 on 93 pump gas and have no problem with detonation.

Here's an extreme example of what you can build into a 3.0

Gert’s Engine Rebuild & Upgrade (Chasing 300Hp, yes another one sorry)

[Tom '74 911]

The prevailing sentiment seems to be on the side of a 3.6L so far from what I'm reading. I was at this exact junction a little over a year ago. . . and went w/the 3.6L. I would say in hindsight that unless you are trying to meet a specific race class or displacement requirement, that you should go with the solution that will result in the healthiest engine when the dust settles. By healthiest, I do not mean the one w/the most power, but the one that is in the best condition and will offer you the best reliability and trouble free running. I will also caution you (in as nice a way as possible!!) that depending on your expectations, $16K is the tip of the iceberg.

[JeremyD]

or this 3.0 from my friends at JB Racing...

JB Racing - Race Cars & Parts For Sale
357 hp @ 7900 rpm / 260 FT. LBS.TORQUE @ 6200 RPM



Tom - if you were to start your project with what you know today - what would you do??

[KTL]

The cheapest way i've seen the 3.6 done is to buy an already converted car and swap it into the car of your choice. einreb asked me to help him with his insanity. He bought pbs911's 3.6 '78 Targa off of ebay. Had it delivered here to IL and stored/converted at my house. We took apart the '78 and put the goods in his '88. The 3.2 went into the '78 and made it still be a nice little upgrade for an SC, albeit not the rorty 3.6 hotrod it once was. einreb sold it locally to a friend in our group of goofball 911 owners. All told the conversion process/car swapping probably cost $10-$12K after buying the '78 and selling it off. That's hard to beat.

Since we were going from the '78's 915 to the '88's G50, we had to source the appropriate flywheels and clutches. Aside from that, it was a pretty straightforward swap with the help of this forum and Steve Timmons at Instant-G.

[uwanna]

Back in '92, I bought a 20k mile 964 3.6 complete with G50 for $6k. I then spent less than $3k in buying all the parts I needed to do the conversion which included a brand new in the crate 915/73 LSD trans from PAP for $1500. (no conversion kits back then, had to backyard engineer it all on my own). Then sold my old 3.2 and 915 for $4000, and the G50 for $1500. My total cost at completion netted out at $3500, not counting my labor! The car is an '80SC which I had previously upgraded to a 3.2 Carrera motor, but was not satisfied with the meager performance increase. Still own the car today and after 40k additional trouble free miles on the 3.6, it still runs like a rocket. After eight previous 911s and all my attempts at performance upgrades and improvements, the 3.6 solution was the end of my quest.

[Tom '74 911]

Originally Posted by JeremyD

Tom - if you were to start your project with what you know today - what would you do??

That's a good question - I don't think I have an easy, automatic answer. At the end of my first track day last summer I asked myself if the day had been more fun w/my new drivetrain - was it $XX,XXX.xx (the cost of all the drivetrain upgrades) more fun? The obvious answer was no. I had just as much fun w/my old 2.7L as my new 3.6L - albeit at a slower speed!

These cars are crazy capable in stock form I think. For street driving, never once did I feel the 2.7L inadequate (well maybe a few times). My thought on street driving however is that if you're consistently driving these cars to the limit on public roads, you should be thrown in jail. That's why I go to the track. My main point there is that so many people focus on HORSEPOWER and in the end, unless you're wheel to wheel racing, it's not as important as it's made out to be (just my opinion).

When considering swapping engines, I looked at EVERYTHING. Rebuilding my 2.7L was going to be close to $20K to get what I wanted. I was quoted $25K+ for a rebuilt 3.2L Spec 911 type motor from a top tier shop. I was hesitant to buy a used motor in basically unknown condition. To me, it all came down to value. Given the research I'd done, my budget and thinking at the time, I was set on a 3.6L and wouldn't have been happy w/a stockish 3.0L or 3.2L. Given hindsight, I'd now be happy w/a nicely built 3.2L. If I could've afforded it, I would've bought a motor like the JB Racing one you posted - but $35K was/is out of my range. I looked for a 3.6L for close to 2 years and I held out until I found one that had been rebuilt w/crazy low hours (10) and bought it from someone I grew to trust. I paid a lot for it - probably 2/3rds again as much as what used 3.6Ls go for. I didn't do the rebuild myself and do still fret every so often about its health (not knowing for certain because I didn't do it myself). My fingers remain crossed that it will provide many years of trouble free service. I did also buy a new/rebuilt 915 to go w/it, from G-Box.

Sorry to be so long. In a nut shell, I would make long term engine health and reliability my first priority given my budget - which wasn't skimpy I might add.

EDIT - just wanted to add that I DID do all the install/conversion work myself, in my own garage and still (just) got to a number w/2 digits before the comma. I'm sure it can be done cheaper, but that was not the path I took.

[gavinc69]

I am in or was in he same position. In the end I decided to have my 3.0 rebuilt and tweaked for a little extra power for now, that way I get a nice fresh engine ready to turbo charge in 12 months or so's time.
Ninemeister in the UK are doing the rebuild, 993 cams,993 studs, ported & polish heads and cutting the valves to RS spec.
Hopefully the car should be back at the end of the month.
Im also now starting to collect parts for the turbo conversion.
I guess I didn't want to spend money on a used unknown engine plus I just love the sound of a Zork tube on a turbo 911

[porschenut]

Originally Posted by JeremyD

I really think that for all the $$$ I've forked over I might be inclined to fork over the money for a lower mileage (or rebuilt on someone elses $$) later car (964 or 993) and go with the whole car that's been built from the ground up with those systems in place.

I agree completely. Maybe sell the Carrera, buy a 930 and add a 1 bar boost spring for an easy 400 hp. Plus, such a car will hold its value much better than a car with some sort of non-stock engine or conversion.