sj_hendrikx

Hi there,

I'm thinking about buying an sc coupe. Ans i read all about the differences between 78-80 81-31 and the euro and US models. Mostly it comes down to compression and some minor things. In Holland where I live, good SC's are not there any more, because of salt on the roads, so we import a lot of US cars.

now my question: Is there any way that I can up the power a bit of the US models? (20 HP or so) without losing mid range torque? and prefferably without changing internals like pistons etc?

In holland, pre 1991 cars have no environment rules.

Im thinking:
-air filter
-cat delete and SSI
-PMO carbs (good sound!!)
-ignition timing etc.

any advice?

third_pedal

There are a couple of ways you can get more horse power out of an SC. The first way and the way I would recommend is to add SSI heat exchangers to the car. This will give you a substantial power upgrade. You could also add a cat-bypass which would give even more horsepower of added. The last way and most costly is to redo the gearing on the car. If done correctly it will add a substantial amount of horsepower even more then the ssi's and the cat-bypass. A good Porsche shop can point you in the right direction on how the gearing should be done.

Amber Gramps

Gearing doesn't add horsepower. A rear tire that is smaller in circumference (by as little as an inch) than the stock tire will allow the car to accelerate quicker because it lowers the gear ratio.

My path to better performance has been to put the car on a diet. Much less expensive than bolting on go-fast parts. Second gear in my car causes even seasons Porsche guys to question what is wrong with their own cars. My car is simply lighter than theirs.

DoninDen

+1 on the non cat SSI.

Anybody with experience with the cost/benefit of adjusting/changing the cam on a non cat SSI car?

third_pedal

Amber Lamps was right, gearing doesn't add horsepower. However gearing better utilizes the power from the SC's engine improving the car's performance significantly. This is an expensive upgrade but it will do wonders for your car.

Reiver

Some good suggestions but why not source an '83 930-10 204 HP euro for your US body/chassis?
If the older 911 SC's are rusting out they have to do something with the engines.
A Euro with SSI's and a proper sport muffler will get you 220 HP or a bit more.
Then lighten the car up.

JCP911S

On a US car, headers (or SSI) without CATS and a straight exhaust can get 15HP. The cheapest.

Without cams, the PMOs won't help you much.

Lowered weight and suspension mods will give you the best improvement in lap times.

If budget allows, close ratio gears will give you huge benefits in acceleration up to about 110 MPH, but reduce max speed.

Its all a trade-off... how do you plan to use the car?

Gears are extremely effective for performance, but you have to understand their use... they give much better acceleration on a road course, but limit top speed.

PMOs, cams and High Compression pistons will give another 30HP... but at great cost.

Having spent 20 years in HPDE and Racing in these cars,