Why don't more people turbo the 3.6's?

[njansenv]

I've read a handful of posts on turbo'd 3.6 964's and 993's...and am surprised at how few have been turboed. There are quite a few supercharged cars out there, but not many turbo'd cars? Why is that? It seems you can make a ton of power on these with a basic turbo setup and machined stock pistons (964). The availability of Megasquirt and VEMS makes it easier. Am I missing something?

[Tippy]

Probably due to people hanging on to the "last air-cooled" 911, not wanting to molest the "best" air-cooled 911.

964? Good question. Prices are pretty good and a great car overall to start with.

I suspect it's simply not enough vendors making kits?

Me, I'd kill for a 993 C4S in black, 8:1 CR, and a huge snail with around 1.5-bar........mmm, mmm.....

[Jim2]

I think what you said about having to go inside the motor to reduce compression is a significant hurdle for most enthusiasts who would prefer bolt-on DIY arrangements like the current supercharger kits.

For turbo'ing there is a host of other issues which require custom built parts, which by comparison retrofit from a 930 onto pre 89 911s making them viable turbo candidates. Having BTDT I found that nothing retrofits onto the 3.6 platform so you'd require custom headers, oil scavenge system, engine tin mods, inlet pipe, intercooler, etc and there is difficulty with space due to the twin head distibuter, clearance issues with factory heat ducting components and space for a decent intercooler, list goes on and on. Even the intake manifold has issues as it was never designed for pressure so all the rubber unions pop apart much above 6 psi.

The 911 and 930 chassis are free of clutter whereas the 964/993 are more like modern cars with space constraints, just more custom stuff to deal with which would become cost prohibitive.

[Jim2]

Me, I'd kill for a 993 C4S in black, 8:1 CR, and a huge snail with around 1.5-bar........mmm, mmm.....

Hey Tippy, your dream car IS otherwise known as a 993tt!

[njansenv]

Fair enough.

I have a 'driver quality', no-history 964 C4 that needs new head studs and a reseal - at that point, machining the pistons seems incremental.

With Megasquirt or similar, going to COP ignition would solve the distributor issue, and the costs would largely be covered by the sale of the stock parts.

So my thoughts are:
1) machine pistons when resealing the motor
2) install MS as Naturally aspirated
3) bolt on a GT35R where the cat converter is as time permits. Basically the Ruf RCT solution...

Yes, I know I'm simplifying, but it sure sounds like a 'not unreasonable' path....

[Tippy]

Quote

Me, I'd kill for a 993 C4S in black, 8:1 CR, and a huge snail with around 1.5-bar........mmm, mmm.....

Hey Tippy, your dream car IS otherwise known as a 993tt!

I rather have the simplicity of the NA and a single turbo though. Plus, I rather not molest the TT. It's held in a higher regard in my eyes.

[Tippy]

Fair enough.



I have a 'driver quality', no-history 964 C4 that needs new head studs and a reseal - at that point, machining the pistons seems incremental.



With Megasquirt or similar, going to COP ignition would solve the distributor issue, and the costs would largely be covered by the sale of the stock parts.



So my thoughts are:

1) machine pistons when resealing the motor

2) install MS as Naturally aspirated

3) bolt on a GT35R where the cat converter is as time permits. Basically the Ruf RCT solution...



Yes, I know I'm simplifying, but it sure sounds like a 'not unreasonable' path....

My question would be how much material would be in the piston crown after machining? Too little and the piston won't be strong anymore. It would take a serious rebalance too I'd imagine.

Plenty of MS'ers to help, some with COP. If you want to make your life easier, look into EDIS to get going possibly.

[Tilikum Turbo]

Resale value will take a hit afterwards, because it's no longer stock.

I think especially a 993 would take a serious resale value hit afterwards. A factory 993 turbo
compared to a 993 that has been turbocharged are not the same animals.

It's all a slippery slope, just some more slippery...

[Uncle]

Anything can be done it's just a matter of is it worth doing. In this case you might just be better off looking at a 965 motor.

[TurboKraft]

Resale be damned, a turbocharged 964 or 993 3.6L is a fantastic, awesome engine with an enormous power band. Quiet valvetrain, smooth, responsive, durable. Sure, quite a bit of fabrication, but what's not to love about the results?
365whp/370wtq @ 0.5bar
450whp/460wtq @ 0.9bar
520whp/550wtq @ 1.2bar



(budget minimalist version for track)


If you could drive a 964 with an RCT-style engine, or a plain all-stock 964, what are you going to drive? :-)

[Tippy]

My lord that torque!!

[Uncle]

Chris, what are you doing to keep the plastic intake manifolds together at 1.2 bar?

[TurboKraft]

Originally Posted by Tippy

My lord that torque!!

Yeah, no kidding!

Here's an overlay of that purple car (red line) vs. a 993TT (yellow line), and the same boost (within 0.5psi).

The 993TT had free-flow cats, RSR mufflers, K1624s, fuel pressure regulator, and a sport ECU program.

The basic single turbo 964 wins everywhere, even making more torque at 3,000rpm than the Twin Turbo.



So much for single turbos having a lot of lag.

[TurboKraft]

Originally Posted by Uncle

Chris, what are you doing to keep the plastic intake manifolds together at 1.2 bar?

Upgrade all the rubber connectors between the manifold pieces, plus brackets to keep the manifold from popping up and popping apart.

The intercooler mounts to a plate which also serves to hold the manifolds together, plus provide a mount for engine sensors, idle motor, boost solenoid valve, relays, etc...

Tested at pressures over 1.5bar on race fuel, no problems thus far.

[Uncle]

OK cool thanks for the info. The plate seems like a good soltion to the movment problem.

[Jim2]

Chris, what static compression ratio is this 3.6 in the red car, and what fuel to run 1.2 bar? (if you don't mind saying)

964 cams or something else?

I could go on with questions...

Turbine dia and A/R?

I'm done now.

Thx!

[TurboKraft]

* 8.0:1 TK-spec pistons & LNE cylinders
* stock 964 cams
* stock heads except Turbo exhaust valves (sodium filled)
* stock 964 exhaust manifolds -- this was a budget job
* Garrett GT35R with a T04 flange -- kept the turbo "small" for response and midrange torque, but larger T04 flange so the client could switch to a bigger turbocharger in the future if so desired
* AEM engine management

Tuning done on 91-octane, except "high" was on 100-octane as that's the lowest octane race gas usually available. This was a conservative enough build that we could have tuned "high" to run on 91-oct pump gas.

[totle]

Great result Chis:-)
Nice build as always

[clutch-monkey]

this tempts me

except my gearbox would explode

[Tippy]

What box you have clutch-monkey?