3.6L rebuild options

e3photo · 08-22-2009, 08:33 AM

OK, time to start firming up some ideas and direction for my next project. I had been looking for a high mileage 993 without luck, so when I ran across a deal on a 3.6, I jumped on it. The engine came out of a 97 C2S with 70k on it. I bought it as a long block with extras. It came with varioram, fuel rails, full exhaust (- one muffler) and a couple of flywheels and plates and two boxes of misc.
I want to tear it all the way down and build it back, tweaking where I can. I have read everything I can find and it seems most don't consider going to 3.8 is cost effective. This engine will eventually end up in a 993 daily driver, maybe an occasional DE, so 3.8 would probably be overkill for me.
There just seems like there ought to be a sweet spot between stock and 3.8. I know you can get a lot of bang from a chip and sport muffler, but what else?ss cams? Can the varioram be ported any, sort of a mild approach to what 9m does?
I am basically hoping to get enough input to create a recipe for the motor.I will probably cross post because RL has the greatest 993 following, and Pelican has a higher number of engine rebuild participants.
Let's build an engine.

NoEardGoat · 08-23-2009, 06:57 AM

I bought a 93 3.6l motor that ended up having a broken piston ring. I wonder the same thing? Is there anything one do while rebuilding the motor to get a little more power, without braking the bank?

The only inexpensive things I have really seen so far is upgrading to Ti valve springs, chip, exhaust, RS pulley,

The 993 motor has a better designed crank that doesn't need a balancer, so your ahead of me there.

Someone is gonna say it so I will just say it right now. Twin turbo would get you plenty of Hp.

NoEardGoat · 08-23-2009, 07:03 AM

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e3photo · 08-23-2009, 08:54 AM

Hey NoEardGoat,
that would be quite the setup. I think I am going to stick with the non turbo route.

I had a reply from Steve Weiner on another forum and he said...

"I can tell you without question that a properly built 3.6 with RS cams, RS intake valves, good software and exhaust will make 305-310 BHP (more with a race exhaust). With the RS LWF kit and close-ratio gears, that makes a VERY potent package. "

I think this is the path I am headed down. I think you are right in that I have it easier with the 993 engine, and I have the varioram. Are you thinking of varioram upgrade, or PMOs, or stock fuel injection? Good luck with it and keep me posted on your path.

Cheers,
Emerald

Raceboy · Raceboy's Garage

I would suggest going ITB's with standalone engine management and better cams (RS maybe) together with some exhaust mods. That will get you great power with absolutely best throttle response.

NoEardGoat · 08-23-2009, 10:29 AM

Unfortunately I have to keep costs to a minimum so I plan on leaving the bottom end alone, having the head redone, putting it back together, and just running the stock 964 injection. I need to have the heads done so I maybe upgrading some parts in there. I have some bad spots on the cams so they will need to be refreshed, but I live in CA so I don't think I can run RS profile cams and still have a shot a passing smog. For exhaust I have a set of 993 HE that I cut the flanges off to flip around. For now I need to work on wiring and fuel line setup so its ready to go when the motor gets done. Not really looking forward to it...

Steve@Rennsport · 08-23-2009, 10:44 AM

Quote:

Originally Posted by NoEardGoat

The only inexpensive things I have really seen so far is upgrading to Ti valve springs, chip, exhaust, RS pulley,

FWIW,..Ti is ONLY used for the valve spring retainers, NOT the springs (thankfully).

Quote:

The 993 motor has a better designed crank that doesn't need a balancer, so your ahead of me there.

The RSR's used the stronger 964 crank as it has more rod bearing area for durability at high RPM.

The 993 cranks are OK, but not the preferred item for engines that will see north of 7K.

Raceboy · Raceboy's Garage

Quote:

Originally Posted by NoEardGoat

Unfortunately I have to keep costs to a minimum so I plan on leaving the bottom end alone, having the head redone, putting it back together, and just running the stock 964 injection. I need to have the heads done so I maybe upgrading some parts in there. I have some bad spots on the cams so they will need to be refreshed, but I live in CA so I don't think I can run RS profile cams and still have a shot a passing smog. For exhaust I have a set of 993 HE that I cut the flanges off to flip around. For now I need to work on wiring and fuel line setup so its ready to go when the motor gets done. Not really looking forward to it...

If you want to gain hp, then changing injectors to bigger ones is A MUST on 964 as those are barely adequate even for stock power (250 hp).

And going programmable EFI on 964 is not as hard as it may look. Check this thread: FS: VEMS PnP Motronic for 964

NoEardGoat · 08-23-2009, 01:30 PM

Quote:

Originally Posted by Raceboy

If you want to gain hp, then changing injectors to bigger ones is A MUST on 964 as those are barely adequate even for stock power (250 hp).

And going programmable EFI on 964 is not as hard as it may look. Check this thread: FS: VEMS PnP Motronic for 964

Do you have a suggestion for injectors? I still need to be able to throw the computer in a MAP that can pass CA smog req's. what about cam uprades?

Raceboy · Raceboy's Garage

It depends on the power goals you have. Roughly the required injector size in cc is the number of hp you want. Like if you want 300hp, then 300cc injectors are minimum. Stock 964 injectors are 220cc IIRC but 964 has higher base pressure than 3bar (it was 3,8 IIRC), that's why it gets away with these minuscule injectors, but it's barely adequate with stock power.

If you look for injectors, avoid ancient EV1-type crap (the ones that look like stock fat-type injectors) because the have poor response and atomization. Prefer newer, pencil-style injectors, they are directly swappable with the old ones.

They look like this:

With properly tuned standalone, modified cars pass smog tests easily assuming the cats are still present and sometimes even without it (depends on lot of things).

Jim Dorociak · 08-23-2009, 02:12 PM

Just a thought - I know you have your sights set on a motor project --- but! The Varioram in stock configuration produced 282 hp. If you have a brain than can change a chip or have your dme re flashed then in stock configuration 300 hp is not a difficult task. If the engine does not need a rebuild - then do not do it. PMO's, ITB - RSR intakes - anthing else that you plan in your project will quickly turn it into mega bucks and the slippery slope begins. You have enough dollars to spend just to put your engine back into a complete form. Do you have a 97 or 98 brain? How much of your Varioram is missing? - Prices for PMO's are not cheap, and then you need crankfire ignition or some other method to fire your twin plug engine. Jim

Steve@Rennsport · 08-23-2009, 02:42 PM

Great advice from Jim D,...

Beyond an ECU upgrade, I'd spend the money on close-ratio gears,........

e3photo · 08-23-2009, 07:19 PM

Thanks for the great input Jim. I do not have a brain yet

, as I only have the engine. I guess I could wait till I find a car, and maybe look for a specific year. I am going to do a leak down per Steve's suggestion, and then go from there. I do not know the history of the engine except it has 70k and is relatively clean. I just want to make sure that once it is put in a car, it will be a reliable daily driver. I am not sure, but I think I have a pretty complete Varioram. I am missing the distributor and alternator/fan assembly.
Thanks again for the input.It is always good to have a different perspective.

Cheers,
Emerald

DW SD · 08-24-2009, 01:56 PM

Quote:

Originally Posted by Steve@Rennsport

FWIW,..Ti is ONLY used for the valve spring retainers, NOT the springs (thankfully).

The RSR's used the stronger 964 crank as it has more rod bearing area for durability at high RPM.

The 993 cranks are OK, but not the preferred item for engines that will see north of 7K.

Steve,
When the factory used the 964 crank, did they run a special harmonic balancer? Or leave it off? Patrick Motorsports claims no reported crank breakages with the use of their crankpulley for eliminating the harmonic balancer.

Emerald,
I'd keep things very simple and advocate not spending additional $ where they may be unnecessary. Chip and exhaust should put things into a nice power range.

You could consider use of the earlier 964 cams along with a cam upgrade, which wouldn't be terribly expensive. I use a 993 supersport grind which has a nice flat curve, but seems to offer improvment. Maybe the solid lifter can follow a more aggressive profile than the hydraulic lifter?

Email me and I'll send you back the dyno #s for my setup (3.6, '95 non vram intake and engine management).

Doug

Steve@Rennsport · 08-24-2009, 02:06 PM

Quote:

Originally Posted by DW SD

Steve,
When the factory used the 964 crank, did they run a special harmonic balancer? Or leave it off? Patrick Motorsports claims no reported crank breakages with the use of their crankpulley for eliminating the harmonic balancer.

Doug,

The factory used a simple pulley; plain sheave and later, multi-ribbed for durability.

No additional balancer was used. The Patrick pulleys are OK, but a bit small so we make a larger one that maintains fan speed and cooling.

e3photo · 08-24-2009, 06:08 PM

Well I did my first leak down test. Did it several times, because it is not that intuitive. I used the tester from harbor freight. I think I have 10% on 1 and about 20% on the rest. I can hear the air escaping past the valves. intake on 3 - exhaust on 4,5 & 2 and intake and exhaust on 1 & 3. Does this sound about right? Anybody have a set routine they like when using the harbor freight gauges?

Cheers,
Emerald

e3photo · 08-25-2009, 06:50 PM

I also did not hear any air escaping thru the oil filler, which is good. I guess next I will start breaking it down, and send the heads to Steve for some work. I guess next will be inspecting P/C's and rings and such.

Cheers,
Emerald

TimT · 08-25-2009, 08:17 PM

I say toss a mountain of money at it

Get ITB's, and then mount the vario ram plenum on top of them.....I suppose you could use the stock DME and have a chip burned to suit...

so many different paths..

well that's my plan for an engine I'm building right now... but smaller displacement..

CaptainCalf · 07-09-2010, 04:47 AM

Sorry for the dust in your face, but did OP get that motor built? I ask cuz I'm looking at '95 3.6L with 120k miles as a candidate for rebuild....

Are the 1995 brains flashable at all or will I need a later model ECU that's programmable?

Thanks,
Rick C.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by CaptainCalf

Sorry for the dust in your face, but did OP get that motor built? I ask cuz I'm looking at '95 3.6L with 120k miles as a candidate for rebuild....

Are the 1995 brains flashable at all or will I need a later model ECU that's programmable?

Thanks,
Rick C.

The '95s have a user replaceable chip