3.3 Turbo into '78 SC

Slideorama · 07-02-2004, 05:56 AM

Hi guys looking for your advice on a suggestion from my engine builder.

I have a '78 SC which is getting pretty tired in the engine department. I use the car as a daily driver with de's and autox when they are on. I have been searching for extra horsepower since purchasing it. I have already upgraded brakes/suspension and installed safety items such as rollcage and raceseats. I've been contemplating a 3.6 transplant but the initial engine cost and then the work required to fit over here in Australia is quite heavy.

My porsche engine builder is a friend he has a lot of interesting odds and ends lying around including a 3.3 Turbo motor. He is in need of a 3.0 engine for an SCRS tarmac rally car, he has put the following proposal to me -

Buy his 3.3L Turbo case with raceware fasteners, crank, barrels and pistons (hasn't been run since rebuild).
Car currently has has carillos which he will replace with standard rods (to lower cost)
Reco my 3L heads and use.
Use my SC cams and rocker boxes, injection, alternator, fan, tinware, clutch etc.
Use 3.2 exhaust manifold modified for turbo.
Garrett turbo and custom muffler.
Custom intercooler (seen his work it really is great).
Basic fuel controller and bigger fuel pump.
flywheel?

Question is does this sound like a decent way to go to improve torque and horsepower in an SC?
What kind of horsepower/torque figures should I expect from this setup?
What type of flywheel would be used to mate to a 915?
Any major flaws in the plan?

Price is within budget for me and to me it seems like a resonable plan but I'm a long way away from being an engine expert!

Any help greatly appreciated.

Brad Fisher

BURN-BROS · 07-02-2004, 06:03 AM

Just be easy on your trans. And I see no flaws.....power good.

Slideorama · 07-02-2004, 06:25 AM

I've read that the 915 is capable of up to 400hp? Is this correct? Mine is in pretty good shape and I wouldn't think the above engine would pushing anywhere close to that horspower?

BURN-BROS · 07-02-2004, 06:35 AM

It is capable with a billit side cover and other mods but I do not know for how long. Did 78 have an aluminum trans? How will you drive the car(track/street)?

David · David's Garage

What would you use for an intake manifold? It would probably be easier to find a stock 930 exhaust rather than modifying the 3.2 exhaust.

Slideorama · 07-02-2004, 06:51 AM

yeah '78 had aluminium trans. Car will be mainly used for street as a daily driver but with use on track/autox/de's etc. on weekends.

Really appreciate your help.

BURN-BROS · 07-02-2004, 08:13 AM

No problem. Welcome aboard. I am sure others will post their opinions/experiences so you can make the best decisions for your situation . David has brought up some good points, your budget may not factor these things in.

KobaltBlau · 07-02-2004, 09:45 AM

Sounds like lots of fun. I second the recommendation for stock (ROW, which shouldn't be a problem for you) 930 exhaust.

On the 915, I think the most important thing on the track with big torque (aside from respecting the trans) is to keep heat under control. I posted some info to that effect on a thread yesterday (with hints on searching) here:

Looking for 84-86 915 Transmission

unfortunately, it's in the for sale forum.

rick conrath · 07-02-2004, 11:11 AM

Unless your friend is going to give you a great deal on the machine work, I have some concerns about your budget. I think that you will find the cost of the tubo conversion will be as much if not more than a 3.6 , especially if you are paying for the switch from CIS to EFI. You will have to buy an engine management system and port the heads to match 3.2
The metal composition on the 3.0 heads is also not like the compostion of a true 3.3 turbo head. I bet you will spend every bit of 10 -15 K to hit the 450 hp threshold...and now for your transmission. The 915 isn't going to hold up with that kind of abuse.
I already had a 3.3 and was 12k in parts before I decided to twin turbo a 3.6 to save on the porting and custom fabrication costs. Sounds like fun, but the costs will add up quickly.
Rick
'78 930

Wayne 962 · Wayne 962's Garage

Sounds like a lot of trouble here. For one thing, you can't use your SC injection for the turbo. Also, driving a turbo is very different than a normally aspirated car...

-Wayne

Henry Schmidt · Henry Schmidt's Garage

Wayne is right, the SC injection is not appropriate for a turbo engine.
That said, 300 hp, 280 ft/lb torque. What could be more fun. I have build 3 911 SC for my own use with turbos and they are great. If you can build a non intercooled engine so you don't need a tail you end up with a wolf in sheep's clothing.
As for the clutch and trans issue. Use a Center Force clutch package and don't pretend to be John Force and you'll be fine. I wore out two set of rear tires in 16K and had no trans issues.
Good luck

BURN-BROS · 07-02-2004, 01:11 PM

I picked up a complete Euro CIS turbo intake/injection system for a good price. If your budget is thin, go that route and do some porting to the intake manifold. Longer intake studs will be needed as well. Unless I have missed something this would take care of most of the issues.

Slideorama · 07-03-2004, 12:39 AM

thanks for your advice. Any other suggestions gretaly appreciated.

excuse my noobiness, I thought the sc's and the 3.3 turbo's both ran cis/kjet intake injection.

David · David's Garage

They both run CIS but it's a completely different system. The little parts may interchange, but the big expensive parts are all different. The easiest approach would be to find a CIS system off a 3.3 turbo. This shouldn't be that hard since so many people are going to EFI.

Actually the easiest, and probably cheapest approach would be to buy a complete 3.3 turbo engine. They go for about $7500US around here.

350HP930 · 07-03-2004, 05:44 PM

Quote:

Originally posted by Henry Schmidt

That said, 300 hp, 280 ft/lb torque. What could be more fun.

Thats weak . . .

Even during its end days my 930 had over 325 lbs of torque at the back wheels.

Slideorama · 02:37 AM

Ok got a bit more information from a session with my engine builder yesterday -

3.3 case
3.3 crank/rods/pistons/cylinders (8:1 comperssion)
raceware fasteners
3.0SC heads machined and rebuilt to suit application
3.0SC cams
k27 turbo
Custom intercooler
3.2 headers/heatexchangers, custom muffler

intake still seems to be the big killer...will look for row 3.3 intake as suggested (by you kindly folk here!) or maybe look at motec?

I'm looking for something that is reliable enough to drive everyday, but still packs a good punch on the track when required. I'm used to driving high horspower turbo cars and the standard power (not enough!) of the SC has led me to here.

Car already has brake and suspension upgrades performed, rollcage installed, turbo 7 & 9" wheels, turbo tail and front rubber, waiting on racing seats and all the rest of the interior is off at the retrimmer now! Just need it to go as good as it looks!

I'm also very interested in any suggestions of rebuilding my sc3.0 maybe as a turbo 3.0? Anyone here gone down that road? Am I going to run into the same induction problems as with a 3.3 or will 3.0 cis handle adding a turbo to a nicely rebuilt motor?

Thanks again for all your help and putting up with a porsche engine noobie.
Brad

rick conrath · 07-04-2004, 05:41 AM

You have a good formula here. What are you going to do for engine management? You know...Motec should be familiar to you based upon where you live. Not cheap, but very reliable. I think the hardest part of your setup is going to be the manifold, throttle body position, and intercooler setup. If you can find a 993TTthrottle body and intercooler, you are half way home. Many guys just flip the 3.2 manifold around facing forward if you can't find one of those....I know that I couldn't.
Stick with the intercooled 3.3 engine vs. the earlier 3.0 setup. I would definately not go though this whole exercise and then leave a bunch of horsepower on the table.
The jury is mixed as to whether you will see any long range problems using non-turbo heads in a turbo application. As I indicated earlier the metallic composition is different, and with my research I found several very reputable machine shops that advised against that route. The non-turbo heads will work, you just run the risk of cracking around the valve seats. Before you spend gobs of money setting up your heads, I would look to see if you couldn't find a turbo set.
Hope this helps.
Rick
'78 930

iamchappy · iamchappy's Garage

Follow this thread if your interested in turbocharging your 3.0.
I did it to my 3.0 and am quite happy with the results.
911SC Turbo

Mark McClure · 07-07-2004, 10:36 PM

Slideorama are you talking with Michael harris?

Cheers

Mark...

Fishcop · Fishcop's Garage

I'd be inclined to spend my money on your own SC engine with upgraded pistons, injection (or PMO carbs), and camshafts. A well sorted 3.0 should give you 240 or 250 hp...

Another good buy are the Host's (Wayne Dempsey) two books and the Bruce Anderson book. Between them you should be able to pin down the type of motor you want to build.