911 SC Engine Power Help
 

I LOVE THIS FORUM!

Ok, onto my question, which is hopefully not dumb:

I have a 1981 SC Targa with a 'fresh' 83 SC Engine. The car is totally stock and runs like a purring kitten. However, I want to find a cost effective way to increase the horsepower. I am trying to avoid removing the engine if possible and completing a rebuild. I have read the backdating the headers and heat exchangers will make a good improvement... what else would you suggest to get more power to the wheels? Also, I do use this car as a daily driver on nice days...so reliability is a needed.

Thanks for your help!!

Try a Steve Wong chip first

It's an SC, no chip. Make it a lot easier if it did:cool:

Exhaust is about the only way without an engine drop...

if i remember correctly a chip can only work on 84 and up engines.^^^^^ beat me to it by a minute! lol

SSI early style exhaust with Dansk Sport muffler. You really feel the additional horsepower. Plus it sounds awesome. Good luck.

Ed Garcia
1977 Carrera 3.0

Oh woops yes, well forget the CIS system. Go with headers or SSI backdate and a muffler. Or add carbs (PMO, Weber). Or a 3.2 FI setup. All not easy or cheap.

the easiest, and cheapest, method is to remove weight from the car. take out anything and everything you absolutely do not need.

ssi+dansk=10hp +/-
ACC 964 +ssi+dansk

Yep. SSI's (which will require an oil line backdate), good flowing muffler, and remove weight. Other than that be sure it's tuned properly and your done.

I would spend my money on suspension and tires first. It makes the car a lot faster per dollar in the twisties.

Exhaust is the standard barer, Carb's also transform these cars, taking weight out is a great idea.

If it was me I would put a cat bypass and sport muffler on it. The difference from going all the way with SSI's or a back date is not that significant in the 4-7k rpm range but dose help low end response and sounds great.

Next I would go after improving my Air Fuel Ratios and Ignition values.

Might start with a wide band O2 sensor or do it on a dyno. Would make it a goal to get to 13 to 13.2/1 AFR's at wide open throttle from 4000rpm to red-line.

Once I had the AFR's dialed in I would go after the ignition side. Probably would go with a programmable MSD and rebuild the advance curve from scratch. The MSD would also allow larger plug gaps that helps with ignition.

Alternately might just put it on the dyno and play with advance till HP is maximized and pull it back a deg or two for safety. Might check with Andial and see if they have a program for the SC's to re-curve the dist from its smog settings to a more performance set up.

Getting the fuel and timing right is equivalent to putting a chip in a newer car. On a CIS smog car getting this part to its best will make for a solid improvement in throttle response, operating temp, and power.

Another opportunity. The euro and some of the US CIS cars have a 'vacuum sensing' WUR that lowers 'control pressure' (this richens the AFR's) with acceleration.

I would make sure I had this or change over to this. This allows an efficient AFR at idle and cruse with a quick increase in the AFR's to a more ideal value for acceleration AFR. Once dialed in should maintain about 14.5 AFR's at part throttle and near 13/1 AFR's with acceleration. This also helps get the metering plate moving with WOT so it creates a little less restriction in the intake tract.

Last, rear wheel diameter can make a difference. Running a 24" v 25" rear tire size can reduce your effective gear ratio about 4% and get you to into your power band quicker.

Couple of easy ones as others have said:

Make sure it is in tune. A/F ratio right on and ignition timing.
Make sure you are getting full throttle. I have seen many that dont.
Take out rear seats and anything else you dont need.

For some $s:
Back date exhaust

For more $s (cheapest to most expensive)
Add carbs - Zeniths, webers, PMOs

For even more $s
Cams, P/Cs

i love new guys.

exhaust.

replace all rubber related to CIS.

suspension

Hp
 

No such thing as cheap horsepower on a 3.0l.
Ask me how I know? see below:D

I feel like a virgin.

It would appear I have my work cut out for me on this one. Perhaps Hershey will offer up some goodies to help me squeeze more power out of it.

Thanks for all the tips. I need to de-viginize a bit and absorb as much as humanly possible about the A/F ratios. I am still learning - but a diligent student.

J

1- exhaust, ssi's or headers and a monty or M&K muffler
2- strip her, gut her, FG bumpers
3- carbs

Thats it. If thats not enuf start thinkin 3.6. Not much more to do.

Anything you do will require the SSIs and the exhaust, so do that first.

I have that, Euro P&C, Euro fuel distributor, cams. Car is fast, pulls hard.

From what I understand, doing the exhaust and going to carbs is a pretty hot ticket. Lots broader power and snap acceleration under throttle.

I also hear that if you have a tranny that has the high gears that going to the earlier ring and pinion is really what you need. My car pulls hard in third all the way to 100. That's kind of high.

My previous 81 euro had the lower gears, and it was quick and fast. It was also geared well for the corners, and would rocket out in second or third. Very nice setup.

If you're thinking of carbs, make sure you can with your state's emissions regs.

Many states you need to keep the CIS.

Yeah. Look I am just an idiot, but what you want is a broad powerband, and geariing that will let you use it. If I get on my SC, get it up over 4K and keep it there through the gears, it will easily run a stock Carrera. But, IMO, a car with the right gears and a broad torque curve will give you a lot of oomph all the time.

SCs are great cars. Well set up SCs are really great.

I am going to Hershey in a few weeks and will look for SSIs and as Dansk exhaust. Good place to start. Although, I fear I may need to pay a professional in case I snap one of the bolts. That would suck... However, here is something interesting I discovered this weekend:

I replaced the spark plug wires with a new set of Beru, and installed new spark plugs, air filter, distributor cap / rotor AND adjusted the valves. WHAT A DIFFERENCE! The car pulls stronger than it ever has!! Although, I may have created a small problem in the process... I am going to post for any ideas on a possible solution.

3 things made a HUGE difference in my 83

1. Recurve the distributor for Mechanical Advance, no retard, 35 degrees inside.
2. Backdate Exhaust/SSI's
3. PMO ITB's with a good EFI setup.

Seriously what made the most difference was the Distibutor Recurve.

The EFI was pretty simple to set up with Studio Tuner. I have no issues with mine except Cold Start and I have a manual Throttle for that... and Im in TX...

You can also upgrade your suspension and it will feel faster...

Good luck...