TR6

I'm curious what performance and reliability upgrades you guys would do if you were rebuilding a normally aspirated 964 engine (bottom and top end). No 3.8 conversion. Assume you are staying with the stock capacity of 3.6 liters and staying within a real world budget (no exotic $20,000 engines). Also assuming the car is to remain a street legal car that is also used for DE'ing and general track events, but not club racing.

Wachuko

Subscribing... I would like to know also... for when the time comes.

Heads from our friends in the UK - 9M??

axl911

TR6,

Balance? Blue printing? RS cam? Porting and polishing? Machining the head to lower compression for your supercharger/turbo?

Or go for the ultimate!!! NOS!!!

axl911

9M heads and ECU rework. I heard most the gain is with the reworking of the 964 head.

springer3

I think it is difficult to get much more without reliability or driveability problems. Balance and blueprint will give some extra power with zero reliability concerns. You will think you got a lot more than you really did because of the smoothness.

Spend some serious money on weight reduction in the rest of the car - that is even better than extra HP, because it helps handling as well. See Robert Linton's threads - he is claiming 2260 lb with full leather interior and working AC. His car will be a rocket even with a bolt stock engine.

deep_uv

I'd spend extra money on reliability. Beefing up the common failure items etc..

Steve

sundog

High strength head studs, and connecting rod bolts.

GT-3 Oil pump, requires minor machining of case (cheaper by 50% than 964 oil pump).

Billet valve covers.

Racing Valve Springs.

TR6

My thoughts too. For example, using ARP rod bolts instead of OEM. Another suggestion was to upgrade the valve springs and retainers to help protect against valve failure at higher revs. Important features in an engine that will see spirited track use.

Another interesting suggestion was to cc the heads to ensure that each of them are at the spec'd 11.3 ratio. I'm told that while the factory spec was 11.3, that most engines came from the factory with varying cc readings, mostly lower than 11.3. I'm told that doing this will give it a little more power with no reliability problems. Not sure what it costs to do that.

Geoffrey

Bob Linton's engine is not a stock engine but a very special engine built for him by his friends at Porsche Motorsport. Like the rest of his car, it is fantastic.

The GT3 oil pumps just went up in price, they are now near $1800 compared to $600 of earlier this year. The pump is much better than a 964 pump, however, 964 pumps have been used as a performance upgrade for awhile.

If it were me, and I was on a budget, I would forgo balancing in favor of building the engine to specifications (blueprinting). I'd use non Porsche rod bearings because the latest bearings from the past 3 years seem to be comming apart and not lasting. We have had problems with delamination and have found rod bearing material in oil filters.

I'd use ARP rod bolts and have the rods resized and balanced as a set. Stock specification is something like within 9 grams of each other and that is a lot.

I'd ensure the engine was at 11.3:1 compression

I'd run a performance valve spring and ti retainer with them shimmed slightly more than the stock installed height for a little more seat pressure. I'd lightly clean up the ports by hand, use a Serdi valve machine for a proper valve job and install aftermarket valves and guides in 8mm stem (assuming you aren't racing the car in a stock class).

964 RS camshafts have the same profile as a standard C2 engine. I might consider an aftermarket camshaft slightly larger than a stock C2.

Use the RSR rocker shaft seals on the rocker shafts to help keep them from leaking.

onboost

Geoffrey,

You mention the use of "non Porsche rod bearings" and the "install of aftermarket valves and guides" along with "performance valve springs and ti retainers"... are there any particular brands, suppliers, manufacturers, and/or specs you would recommend?

Thanks,

Tom W

I second Geoffrey's recommendations. It's the approach taken with my engine.

A comment on the rod bearings. My engine was built about 2 years ago after the original blew up (the technical term for when a rod bolt comes off and the engine gets a fist sized hole in the case). To build the new engine, stock bearings were used with ARP rod bolts, Carillo rods, and stronger valve springs. Earlier this year, the shop pulled and stripped another 3.6 built about the same time as mine and found the bearings were shot. To be safe, and because there appeared to be an issue with the OEM bearings, my engine was also pulled and broken down. My bearings were not great, but not completely shot either (the engine had about 20 hours on it). Mine were probably in better shape because my engine runs cooler (oil temps about 180 °F even when ambient temps are 100 °F due to the 2nd oil cooler and great air flow over both).

My bearing were replaced with a new bearing (different materiall) that should wear better. The new bearings can be obtained from Jerry Woods/Smart Racing Products.

pcarcraig

Greg,

What happened to the engine? I recall that the chassis has some miles on it, but I thought the engine had substantially less. Also, how many miles are actually on the engine now that it's rebuild time.

Thanks

TR6

Don't know what happened for sure yet as it hasn't been torn down yet. But it appears to be a bad rod bearing. Symptom was a tapping noise and copper particles in the oil filter. Still had good oil pressure though. Its waiting to be taken apart as we speak.

The engine is a bit of a story. Its not the original engine that came with the car. A previous owner of my car supercharged the original engine and then swapped that engine with another guy I know locally for his normally aspirated C2 engine (which is what is in mine now). That engine was rebuilt by Porsche under warranty in the mid 90's before it was in my car and now has only about 60-65K miles estimated (the chasis has 145K on it). It has me wondering about the rod bearings that Porsche used when they rebuilt it. I'm trying to locate paperwork on it. Although its a moot point now.

The good news (if there is any), is that I am having it rebuilt by Buckley Racing to a much stronger reliability spec than original. ARP rod bolts, upgraded valve springs/retainers, balancing, etc. Its gonna cost, but it'll be rock solid when its done. I do want to learn more about which rod bearings to use though.

TR6

Okay, here is some of the extra stuff we're talking about doing to my engine for an ultra robust/reliable engine.

1) Jerry Woods rod bearings. They're expensive compared to OEM, but seem like good insurance for a long life at higher revs.
2) Crank: cross drilled and balanced. Cross drilling for more oil flow/lubrication.
3) Upgraded valve springs and Ti retainers.
4) RSR valve seals
5) Compression ratio matching. Getting each combustion chamber close to 11.3 as possible.
6) ARP rod bolts
7) Balancing the pistons/pins.
8) Carillo rods - I'm on the fence on this one. Its going to add about $1300 net extra cost to the rebuild (they are $1775, but if I don't go with Carillo, I still have to spend about $500 on my existing rods to replace one damaged one and balance all of them).

Welcome any comments/suggestions. Is this overkill for a car that doesn't race but does see a number of track days a year? I'm on the fence about the rods because the cost is starting to get a lot higher than I wanted. But its a one time opportunity while its apart. If I were to ever resell the car (God forbid), would having this kind of recently rebuilt engine in it add any significant value? Lots of dumb questions, I know...

BTW, we're also planning to use a new 964 oil pump.

TR6

Comments anyone? Especially on the Carillo rods? Worth it?