Any dyno number on SC with car-bypass?

JackT · 01-22-2003, 04:48 AM

I have seen alot of dyno numbers on 84 to 89s with backdated exhaust, cat-bypass and SSI's but non on SC's.
Does the cat-bypass make a difference on SC's from a performance standpoint compared to the other exhaust options?

chuckr · 01-22-2003, 05:48 AM

I dyno'd my 83SC last year,183HP at the rear wheels. I have a cat by-pass with the Bursch muffler and a K&N air filter.I got almost 20HP over factory spec ! The dyno session was photographed and is on the Austin PCA web site www.hcrpca.org, look under photos then Dyno Day
it lists the mods for each car as well as the results of the run.

Wil Ferch · 01-22-2003, 06:08 AM

The cat by pass by itself should account for 4-7 hp..the rest of the gain from the sport main muffler ( to get a total of 13-20, or so). Caveat...this is for the Porsche pre-muffler piece...YMMV for anyone else'e "straight pipe".
---Wil Ferch

Denis54 · 09-02-2003, 01:17 PM

Chuckr the link does not seem to work. I would like to know the modifications on your car.

MotoSook · 09-02-2003, 01:30 PM

http://www.hcrpca.org/pictures/200104Dyno/dyno_day_results.html

Noel · 09-02-2003, 01:36 PM

Here's the correct link:

http://www.hcrpca.org/pictures/200104Dyno/dyno_day_results.html

Mike Feinstein · Mike Feinstein's Garage

Hmmm. Now I'm concerned. I recently dyno'd 195 rwhp with the identical mods to the car that dyno'd 222.3. Could there be variability in dyno's? Are you sure that this is rear wheel hp? That's almost a 30 hp difference! Car has no issues what-so-ever.

ttweed · ttweed's Garage

Quote:

Originally posted by Mike Feinstein
Hmmm. Could there be variability in dyno's?

Oh yah, big differences. Do a search on "dynos".

TT

JackT · 09-03-2003, 03:31 AM

Has anyone done a before and after dyno with and without the cat by pass?

chuckr · 09-03-2003, 06:00 AM

I hope you got to the link and found what you were looking for.
I did do a before and after on the K&N, the K&N added 7 HP. We had a discussion about the same cars getting much different results. The best answer was that Porsche had some variance on the power of some engines.The story that was told was in Denver Co. the Club there had a Dyno Day and several SC's dyno'd and all had different numbers. I have to admit that I was very suprized at my 183 number, at the time of the dyno I had around 225,000 miles on an untouched motor, granted it had valves done and new injectors but that is it. The only other thing that was not mentioned was that I run Redline Synthetic Oil.I have always been suprized at the dyno results, good or bad at least you know and have some idea of what works and what does not.All I did to the car was a Bursch cat by-pass with Bursch muffler, K&N filter,Redline Oil and new injectors.Swepco tranny fluid.The new injectors helped the most, in my opinion.The funny thing is that two weeks after the dyno my fuel pump went out, it was the origional pump, it had to be weak at the dyno! Hope this helps and Good Luck

Noel · 09-03-2003, 08:31 AM

"the K&N added 7 HP"

That is interesting, as many who have tested mention that there is no change. In fact, running w/o a filter gives no change. However, this was for cars that had stock exhaust. Perhaos with a bybass and a hi-flow muffler, the bottleneck becomes the intake.

Noel