awilli6

Will the porken chips set work with stock injectors? Where can one acquire the 24 lb injectors? Are they plug & play or is modification required? How much are they? 87 S4 with fresh intake refresh looking for more power.

Do you have to get rid of stock cats with x pipe? Not necessarily looking for more sound, just more power. Is professional install required?

Thanks for the answers.

Ash

bureau13

Disclaimer: I have an S3, and don't yet have the chips (but I will) but from what I've read: You definitely need the 24lb injectors to avoid running lean. You can run an x-pipe with newer tech, better flowing cats. Not sure if you can run one with the stock cats, and not sure why you'd want to. I think the choice is between no cats and new cats, although I suspect you could make it work with stock cats if you really wanted to.

bogdann

No mods on the S3 with the 24lb injectors and I got mine off Roger at 928sRus. Also X pipe with new cats. Definite improvement in seat of pants but I never had a before and after dyno.

davek9

He has an S4, NOT an S3 !!!

24lb Injectors are stock on an S3 (stock S3 has lower Fuel Pressure than an S4)

S4 stock has 19lb Injectors, I've not read Ken's requirements for the S4 chips, OP, have you?

http://liftbars.com/indexpk.htm

MjRocket

24# injectors are a requirement, go to liftbars.com and read the requirements its all listed right there.

ROG100

We stock the X pipe and the 19/24Lb injectors.

safulop

X-pipe is not a good option in California where smog results are critical, is it? You still have to have a cat, and I've not heard anything good about the alternative cheapo catalytic converters. Plus we have regulations which say that cats have to be provided by a car dealer, I'm told.

GregBBRD

I'm guessing that most of the "gains" available in this proposed modification occur from removal of the cat. Certainly a reduction in back pressure should lead to better cylinder filling, which probably results in the ability to increase the amount of timing. And Porsche tuned these cars to very (perhaps overly) "safe" at WOT....so removing some fuel usually helps the top end.

Not many "X" pipes in California, without cats. Some people swap cats in and out for smog inspections, the risk being that some "savy" cop will look under the car and see that there are no cats (CHP has training for this). The fines are considerable.

I've seen gutted stock cats (people find a "dead" stock cat and gut it). This will pass a visual inspection and work almost as good as an x-pipe, I'd think. Still need to install the "good" cat every smog inspection....however that is pretty easy.

Tuning (changing or modifying the tables inside the chips) is simply about changing fuel and timing. Individual engines are going to require different amounts of each. The amount of timing and fuel required for optimum performance is largely dependent on compression (this varies significantly in the S4 engines, because of carbon build up) and cam timing of each individual engine. And since there are many different approaches to cam timing (different tensioner designs, cam belts that do not stretch like the stock belt), getting a generic chip designed for one engine is never going to be optimum for another engine. Autothority sold generic chips for 911s for years....some worked good on one 911 and the same chip was terrible for the next 911. When I was very active in the 911 world, we had 12 different chips for just the 3.2 engines....and those computers had a multi position switch inside that would change both fuel and timing for individual engine tuning.

What does all that mean?

Unless your engine is exactly like the engine that the chip maker designed the chip around, your results my differ greatly.

I ran into this problem on one S3 engine. A generic chip designed around one engine was very detrimental to the engine I tried it in....to the point of potentially damaging that engine.

However, that same exact chip set worked fine in another vehicle, with marginal power improvements....not anywhere near the improvements the designer had on his own engine...but some improvement.

Try to remember that engines are like fingerprints....no two are the same...and different engines are going to require different tuning.

Unless you are very lucky, a generic chip is likely to be a disappointment. Sharktuning (individually tuning each engine) will most likely be better.

All that being said, generic chips are relatively cheap....and for the small investment, they are certainly worth a try on your individual engine. However, don't be too frustrated when your results are not the same as those obtained by the designer of the chips....his engine is different than yours!

Approved aftermarket cats are available in 2" and 2.250" sizes....not 2.5".....so they are more restrictive than the stock convertors. (There are ways to get around this.)

Aftermarket cats do not last very long....unless the car is super clean before the cats. Catalytic convertors use precious metals as the catalysist...a used factory cat is worth more to the recyclers than a brand new cat retails for....by a bunch. Pretty simple logic to figure that out.

PorKen

Strange how the stock chip works so well on all of these. 'Tuning' a S4 is difficult, in fact, because the stock chips are fairly close to max performance.

The only option for better response and higher overall performance is to change the programming for more options that are available in the stock code (or that are available with a SharkTuner). Most so-called 'tuners' get caught up on full throttle mapping and forget that the majority of time one drives with the throttle just cracked open. Hundreds of hours go into making WOT as good as it can be on my chips, but they are mainly focused on part throttle response.

Of the myriad of programming changes in my S4 chips, the most advanced is new individual cylinder mapping for full throttle which customizes itself (using knock feedback) for each installation. These custom maps, with ~75 RPM divisions, are saved in semi-permanent memory. On top of this, there is adaptation to the highest permissible overall igntion advance level depending on conditions.

Of course, there are other niceties like a hard and soft rev limit, Sport Mode, which bypasses the O2 loop and enrichens the mix for better part throttle performance, etc., etc.

Ketchmi

Greg, I love ya' man but you are pretty far lost in your X-pipe generalization. The factory cats are indeed restrictive but all my dyno testing involved the best set of cats I tested out of about 10 sets. (not the worst like some places do). The gains I posted are verified by hundreds of customers, not just my bragging. You must know at least a little bit about fluid dynamics, I have seen a lot of your work that demonstrates that. A true scavenging crossover with proper inlet and outlet angles and opening dimension really does provide the horsepower that I advertise. By simply moving the opening 1 inch closer to the ports I lost 10hp. My crossover is optimized for power from every aspect, the 2D mandrel bends included.

The catalytic converters I had made for us are 100cpi and are not intended to last 20 years like the factory part. If they were, they would be considerably more expensive along the lines of factory replacment cats. They are dyno proven to lose less than 5hp and usually show 1.5 to 2 horsepower loss. I specified a higher quantity of "wash" on the metallic substrate than the usual cheaper/readily available aftermarket cats. They are not California legal, what is anymore?

All of my advertised results are from same day/dame dyno testing. Usually not even removing the car from the dyno to swap components. Further tuning will certainly improve my stated figures but that is not what I was trying to demonstrate. My gains are from bolt on and go without any hassle.

Every test I advertised was showing the stock output of the cars beforehand with the stock cats and the 85-86' cars all started at approx 245-250 rwhp and the S4's were 265-270 range which is what I have seen hundreds of times with properly running cars, not with wasted/plugged cats or other problems that could be unknowingly repaired by swapping in the crossover. Big's GTS went from 270 to over 300rwhp WITH CATS!

Greg, your opinion is highly valued but please do not disparage other's achievements without firsthand experience. There is a reason most 928 people don't put headers on their cars, the output levels between headers and my crossover is so small that it's not worth the extra hassle.

BTW, many years ago I gutted the cats on one of mine and ran them. It was horribly noisy and lost power. I don't know why and I no longer care but it was firsthand experience, not guessing.

I have a set of Ken's chips and intend to see what they will do with my latest personal driver. If they work well it will save me from sharktuning it until I supercharge it and are well worth the price if they do.

This dyno sheet shows stock cats vs. Louie's X w/cats vs. mine with cats. Both Louie's and mine used the same high flow cats.

safulop

What a great discussion I accidentally started.

ROG100

I have had Dave's X pipe and high flow cats on my GTS for about 10 years and she passes smog with very low numbers. The operator is often surprised at how clean the car is exhaust wise. Same with Zane's 87 until it was 25 years old.
We also put three cars on the same dyno, same day and same conditions. One manual GTS, one auto GTS and one 91GT. We measured with and without cats on an X pipe and found no measurable difference in HP.

bureau13

Just curious of the Header-X I got from Carl is based on one of these X-pipes. I haven't installed it yet (damn cats are welded to my cat-back) so I can't speak to performance.

Ketchmi

You would have to ask Carl on that one, he has the header X made for him. I do not have anything to do with it.

danglerb

Calif can be very fussy on the visual inspection, or not. Fussy regarding cats means they want the CARB EO# and date off the cats and it needs to match the state smog book. The catch right now is the book says up 90 single cat, with 90 first year of dual cats.

For no problems I would keep a factory cat handy.