GP964

Hello everyone,

Im in a real dilemma here on modifications.
mod#1- "CUP chip" and drilled factory airbox.
mod#2- Autothority Mass Air flow system.

With $$$ not an issue, which mod will provide more horsepower? Has anyone experience any or both mods?

Any info would be appreciated.

Thanks

Kevin

I have a 93 RSA. I installed the Mass Air Kit, which includes a new reprogramed chip. You could really feel the increase in the midrange torque. Since then I have installed the RS lightened flywheel, AutoThority did the second reprogram. The engine is alot more responsive. I have had little to no stalling problems, except the ones on my mistake. Right now as we speak I have rewelded the passenger side 993 heat exchanger (flipped the ears) and am in the process of fitting a 95 993 exhaust system on the car. It will be done with using 90% factory parts. I guess the bottem line is with a mass sensor and chip system, Autothority will always work with you on any upgrade. I will run the car on a dyno to get the results after the 993 exhaust is finished. My goal is to exceed the 272hp from a 95 993, and run close to the 285 to 295 range with the Mass sensor, chip, flywheel, exhaust change.

Kevin

Sorry, I forgot to add, the Carrera RS published HP is 260 horses verses the stock 250hp. Autothority dyno slips are 13hp with +16 torque increase for a chip change. And 30hp rear wheel increase, with +35 torque increase. We must put in perspective that the Carrera RS 3.8 put out 300hp in street form.

Randall G.

Hi Kevin,

Sounds very, very interesting. I am also (re) investigating installing 993 headers on my car.

Perhaps I'm naive, but it seems like some vendor would offer catalytic converter compatible headers/heaters to fit a 964. Remove the primary muffler and place the cat. there, and run the cat's output to the secondary muffler. Am I overlooking something?

Having just heard Tom Sharpes' car this past weekend, I can say that a 964 sounds very nice running on the secondary muffler alone. Hardly louder than stock, with a hint of American V8 sound--but still distinctly air-cooled!

What sort of mufflers are you going to use with the 993 headers, Kevin?

Kevin

Randall;
Well the cats out of the bag. I guess to respond to your first question regarding the Cat situation--Liability $10-$20K fine for messing with the emission on a car. And to make it legitimate the system would have to be certified. Yes there are replacement cats, like the one from Walker, you've probably seen them as a replacement for a stock cat. I am using the stock 993 Cat, and I will use the stock mufflers. There are two problems, the upper Oil line from oil filter, and left rear bumper extension. The after market companies offer a stainless braided line. I'm going to try to modify the stock one. I have plastic welded a C-2 turbo extension to a stock rear extension. Very time consuming. I need help with making a mold. I have contacted AIR, Getty, no one has a fiberglass narrow body extension with a exhaust outlet. I hope to get it fired off this weekend. I will then cut open the mufflers and modify them to get a sweeter sound. I have a second 993 cat that was dropped or involved in an accident and the honeycone material is broken. I am going to turn that into my track test bypass tube, it will be interesting to see the HP numbers. One could then install the RSR muffler bypass pipes, but they are very loud. I would not use them for the street.

GP964

Kevin, Thanks for the info.
Just to clarify

Autothority dyno slips are 13hp with +16 torque increase for a chip change.....just by the chip right?

And 30hp rear wheel increase, with +35 torque increase...for the MAF setup right?

and these #'s are rear wheel hp?

I currently have a K&N filter w/ drilled air box and dual euro rsr exhaust, with a TRE chip....and pushing from my last dyno 233hp at the wheels, take in consideration elevation of 2500-3000 ft above sea level.
80 F temp.

I hope the MAF setup boost the hp even more.

thanks

Kevin

GP964
Yes, those numbers are correct. So for a ballpark figure lets subtract 13 horses,and add 30. We are talking at around 250HP, if you correct for engine to gear train friction @ 20%, we are getting a untested number of 300HP, while you are around 279.6HP at engine flywheel. What type of bumper extension are you using? Posts some pics if you can.

Randall G.

Hi Kevin,

If I understand you correctly, you are making a custom mold to create enough space for the stock 993 mufflers? Is that right? Wow!

You have found that the 993 mufflers won't fit in the stock 964 body, haven't you?

As for a left rear valence panel that has a hole for a second exhaust, I had one for awhile as the 993 engine was being installed in my car. Got it from Performance Products. After it became apparent that we were going to use the 964 exhaust, I sent it back.

Have you considered routing the 993's catalytic converter outputs to the 964's secondary muffler? I don't have the header/disassembled body in front of me, but it seems like it might be easier than widening the fenders--even if it doesn't quite maximize hp.