Twin turbo or 3.6 conversion for a 1983 SC?

Moses · 03-20-2002, 10:22 AM

The SC is a beautifully maintained ex-garage queen with 80,000 miles on it. The cylinders all compression test to 195 and the leakdown is less that 5 pounds/cylinder

The question:

Speedforce Racing can do a twin-turbo conversion complete for under $10K. How will the performance/ reliability compare with a 3.6 conversion?

If the cost were not an issue, which car would you prefer to drive?

widebody911 · widebody911's Garage

I assume you mean a stock, NA 3.6, right?

What's involved in the $10k twin turbo conversion. Sounds way too cheap to me, as my 3.6L conversion (sans rebuild) was much more than that. Sounds like it could be a hand grenade and you don't know where the pin is.

I looked at their site, which had nothing on the turbo conversion. There's a couple of 'bolt-on' turbo conversions out there, which run very low boost. Never ran one myself, don't personally know anyone who is. A guy on rennlist is getting the Protomotive version isntalled on his Carrera right now.

Would be a fun upgrade path, if it works and doesn't grenade your engine.

Jack Olsen · 03-20-2002, 01:05 PM

Juan Ruiz on this board has the Protomotive kit, I think. They start (without an intercooler) at about ten grand. I don't know anything about Speedforce Racing, but you're obviously going to be increasing your risks blowing a small engine that wasn't initially designed for it. A stock 3.6 with low miles is going to run like a tank, pretty much, and when you get bored with 250-300 hp, you can add a turbo to the 3.6, and really kill your 915.

Moses · 03-20-2002, 01:33 PM

The 3.6 seems a more reliable choice if you really love your car. Thanks. Thom, someday when I travel through Sacramento, I'd love to see your car.

juan ruiz · juan ruiz's Garage

Hello Jack,And yes i converted my 3.2 to turbo and yes those $10,000 $$ Sound WAYYYYY to cheap,just to give you some figures my fisrt step was $4999,at this time im having the engine pull and getting a $10,000 up grade to get 500 hp single turbo,so a twin turbo will run in the 30s +, for sure BUT if you do it yourself with used parts, own fabrication are a guru in tune ups you can do it all for under $7500 if you get it right the first time,this depate of turbos, superchargers,etc VS 3.6 in my opinion is a matter of choice whats good for you may not be for the other guy.
just my 0.02
Regards Juan
3.2 Undercover
http://MY88911.homestead.com/newwebpage.html

Jack Olsen · 03:14 PM

And just so I don't sound like I'm knocking the aftermarket turbo systems, let me re-state. I like 'em. They don't lower the CR as much as stock Turbos, so you get more low-end grunt, and less lag.

I may do it one day.

Here's 3.2 based beauty. Click on it to see Protomotive's basic offerings for a 3.6.

(This is what 915 transaxles see in their worst nightmares.)

dean · 03-20-2002, 07:25 PM

Hi
I second or third the opinion that $10k is waay to cheeep to have someone twin turbo your motor.
If cost were no object I would prefer a turbo over anything else. I am a boostaholic.
Dean

cary · 03-20-2002, 07:40 PM

My observations........

I was at RS in Portland a couple weeks ago. There were 3 cars in there getting 3.6 engine conversions.
All track cars .............But all in the NEED for speed.

WydRyd · 03-21-2002, 03:55 AM

Jack, that pic of the Protomotive engine is actually a 3.5L T.T, not a 3.2. It's actually based on a 3.2 Carrera platform, just bigger P&C's and machined case to accept the larger capacity. That's the engine they used in that 1 Mile record breaking 993 C4S I'm told (the silver car on their WEB page). Pretty impressive eh?

I know of two guys, Juan and "Mike The Mechanic" who are running a bolt-on Stage 1 Protomotive system on their stock 3.2's. They've been running these for a while and haven't grenaded yet ;-)

320 Crank HP on 0.5bar non-intercooled. Pretty impressive stuff!

orbmedia · 03-21-2002, 06:04 AM

I saw this one at a tech session at Protosport in NJ. It started out as a 3.2 Carrera but is now a 3.5 twin turbo making 650hp. I wish I had a better shot of the build sheet. This is a Promotive setup with Garret turbos and Tial wastegates.

RarlyL8 · RarlyL8's Garage

Does anyone have pictures of the twin high mounted turbos installed in the car?
I would like to see how the turbos clear all the other parts, such as the oil lines on the left hand side.

It is VERY obvious that NONE of these engines are disigned for anything resembling longevity. Plumbing nightmares that would require removal for the most rudimentary of maintenance issues.

You really have to take a hard look at how you want to use your car, how much you want to spend (time and money) on maintenance, and how much power you really need.
It's really difficult to not get caught up in the flash of all this exotic stuff.

For example, right now I wouldn't hesitate to jump in the SC and drive a few hundred miles. Would or could you do that with an ultra high dollar twin turbo exotic monster mounted out back? I doubt it. Would you do that with a mildly modded twin turbo 930 engine? Yes. I think in the months to come we will see some of the members doing things just like that. Daily driver neo-exotics.
I'm looking forward to it.

beepbeep · 03-21-2002, 10:03 AM

Guys...i'm not trying to sound paternizing, but why do this??

It's cheaper and more reliable to sell your SC, buy yourself a 930 and do some normal mods. Or if you really want power and have $$$ , buy a 930-chassie and dip TT-converted 3.6L-engine in it...

Turbocharging SC's to those figures is costly...and you are probably going to have problems to make that car street-legal as well. 930 is a turbo car, has bigger brakes, sturdier suspension...etc. Use it.

P.S. I never heard about good N/A -> Turbo conversion except pure drag-racing cars ...

dean · 03-21-2002, 10:15 AM

One reason I didn't just sell my SC and buy a Turbo is that I enjoy the proscess as much as the end product. More tinker time during the long winter.
Dean

pbs911 · pbs911's Garage

I agree. Anyone with desire and money can buy a car. What makes the car special to me is the process of creating the car myself.

frogers911 · 03-21-2002, 10:38 AM

Can anyone point me in the right direction (books, websites). I want to get better understanding of turbo charging or super charging an engine. I currently have an 81 SC with 202k on the orginial engine and was just thinking ahead to want I can do for more HP.

WydRyd · 03-21-2002, 01:56 PM

RarlyL8,

I have to disagree on the longevity issue.

These engines are built to be reliable.

We're talking upgraded performance components such as:

complete valve train
head/rod bolts
flame ringed liners
high quality F1 spec wastegates
higher flow oil pumps
larger splash valves
bigger injectors etc... etc...

Obviously the longevity is determined by the way you drive the car and what boost levels you set the thing to run at.

If a 930 can run reliably on 1bar, then these engines with completely upgraded components running 1.25bar should have no problems at all.

Heat is a big factor, so they'd look at every avenue of cooling improvement for longevity. Just check out the size of the intercooler! According to Protomotive, these can be daily driven beasts. Contact Todd Knighton and he'll give you the low down on how reliable these actually are.

I personally would stick to German designed/engineered turbo's such as KKK K24's, but Garrett also has a good track record for being reliable.

Just my 2c FWIW

RarlyL8 · RarlyL8's Garage

Boost kills.

Yes, I'm doing it too. But I'm under no dilusion that running 1.0 bar on the 3.3t isn't going to significantly shorten its life. It is extremely rare for a 930 engine to go 100K miles bone stock without a rebuild. I expect to cut that figure in half with the mods I have. 650hp reliable out of 3.5L? Come on. You know better.

My main point was that I personally would be much more likely to actually drive a car long distances if it had a modded 3.3t vs an exotic 3.2 based twin turbo. The reason is simple. Parts availability and mechanical knowledge. Have a problem with your warmed over 930 and your hundreds of miles from home? Just find a P-mechanic or dealer.

Good parts don't always make a reliable engine. I've got a street machine in my garage with the finest parts that the good ol' boys can thow at it. Reliable? Any engine built on the edge isn't what I'd consider to be reliable. They're all one missed shift away from scrap metal, nomatter what the salesman tells you.

As for supercharging, turbocharging, or engine swaps, a project usually doesn't begin with that in mind. They take on a life of their own, evolving with the owners taste and pocketbook over the years.
I know I sure didn't buy my SC with the intension of swapping in a 930 motor. Hindsight? Yes, I'd buy a 930. Such is human nature.

By no means would I discurage anyone from modding their car and making dreams come true. You only live once. Reality checks are important though.
Your dream can easily become a nightmare.

Frogers911 - there are lots of books out there. Start with B. Anderson's 911 Handbook.
Maximum Boost by Corky Bell
Street Supercharging by Pat Ganahl
all good books to get you going.

Natchamp · 03-21-2002, 06:50 PM

Rarly dude, you are spot on.

juan ruiz · juan ruiz's Garage

Rarly L8,VERY GOOD POINT! When i purchase my car i had no idea what a G50 was,that my car will have this valve guide sicknes,and so on all i wanted was a sport nice car with nice curves, as you mention the proyect takes a life of their own should i know all i have learned in 3 years and money in hand i be driving a 94 3.6 Turbo to start with ,but is like having wine taste with beer pockets! but as long as everyone is happy with their own dream car hell lets share and have fun!!!!!!!!
Regards Juan