Dan87951

I have a 88' 928 S4 auto and also a boosted 944 that will lay down a solid 270HP and 300 torque at the wheels (stock turbo still) and the 928 feels a little sluggish on the bottom end compared to my 944 Turbo. Don't get me wrong when you are on the highway and nail it, boy does it move. Its almost like Porsche put such tall gears in the 928 that it hurt its bottom end everyday city driving performance. I just ordered a RMB exhaust, K&N, and Autoauthority chips and hoping to gain some of that lown end speed back. I have heard the chips don't do much for these cars like the 85-86 but every little bit helps, right? Any other ideas other than a supercharger (currently way out of the budget)

Thanks

SeanR

If you use the K&N, don't put much oil on it or you will be buying a new MAF.

Talk to Roger at 928srus.com and he can get you an X-pipe. That will net you another 40hp.

michaelathome

Headers/ >< - Pipe are a bolt on 40hp from what I have read, that is the easiest quickest HP gain out there. I would try that before the RMB as w/the 88's smaller intermediate mufflers/resinators you might not like the "BWWWAAA" volume. Then again who knows

Michael

Panzer9

I'd bag the K&N- The RMB sounds & looks bad-***. I like the AA chipset, too. Been toying with the notion of an X pipe- But I don't want to reinstall the old "Platopus". I would probably like the sound of the X & RMB. I don't know if my neighbors would feel the same way, though.

Dan87951

Thanks for the info guys but who wouldn't like the bwwwwwaaaaaahh?

byrdman454

If acceleration is what you are looking for, increasing the stall on the stock converter is supposed to be the ticket. I am only talking about a few extra hunderd RPM. Do a search. Killav did it on his S4 auto for a couple hundred bucks and according to him it made a huge difference. I have an extra TC already rebuilt and ready to go in, in addition to a different tranny with the '89-newer 2.54 gear ratio versus the '87-88 2.20 ratio.

SwayBar

This mod is first one to do which will literally change the personality of the anemic automatic S4:

http://members.rennlist.com/v1uhoh/kickdown.htm

http://www.928oc.org/tip/tip093.htm

The S4 automatics should have come this way from the factory. This simple mod really wakes up the S4 automatics!

Unfortunately, not in this case. Ditch the Autothority chips, seriously, and instead use the money saved to buy an X pipe which will give you real horsepower gains.

The RMB will not get you any horsepower, but it sure sounds good with GT resonators, and as a result, is well worth the money!

Bill Ball

The 88 (and 87) S4 has a 2.2 rear-end, so it suffers off the line compared to the 89 which is 2.54, for example. [Oops! I now see Mike already covered that.] But if you can goose the hosepower, the 88 has more top speed potential, of course.

K&N will do nothing except potentially screw up your MAF. There is no measureable power gain and considerable loss of filtering. Take a look at the surface area of the stock airfilter. Must be 10 times the K&N. You can't make up for that with oily cotton.

As sawybar indicated, the AA chips do nothing for the S4s, although they are known to wake up the earlier, more conservatively tuned cars.

Although the RMB adds nothing HP-wise, the sound is glorious and you save 20 or so pounds of useless weight.

X-pipes provide 20 to 30+ RWHP & TQ. They have an odd effect on the V8 rumble and can be quite annoying when combined with the otherwise perfect RMB. Too bad because the power gain is so good.

I haven't tried headers, but they are known to be a good power adder.

GregBBRD

Have the car "Sharktuned" after you get a good exhaust system and forget the generic chips. Indeed, the K&N is worthless....unless you are John Speake and rebuild AFM's. I think he gives barely used K&N's away for free, btw........If he doesn't, I know we have an entire box of them at our shop. Can't hardly get them out fast enough. Just replaced a brand new Bosch AFM this week along with a K&N air filter. I don't know if anyone has checked out the price on a new Bosch AFM lately, but they are not cheap....

gb

Charley B

I'm sure there is something I'm missing, but I just don't get the parallel kickdown switch. Everything I read indicates it induces the tranny to shift down with the application of more throttle but not so much as to activate the normal kick down.

That seems to be accomplishing the same thing as pulling back the shfter a notch or two. the possible exception would be to kick down from 2nd to first, since there is no 1st gear notch. But if your moving in second and want to go to first gear, a quick stab of the throttle kick down, accomplishes the same thing.

Unless you just don't like manually selecting gears, what is the advantage of a parallel kick down?

This may have all been hashed out before, and if so I apolgize.

IcemanG17

Charley
I did hear the the kickdown switch helps alot at the track in downshifting.....from how i understand it (not entirely accurate)...is that with the switch "on" if you downshift to "2" at any speed above about 50mph it WILL NOT downshift..until you reach 50, when your already on the brakes.....I did have some problems locking up the rear end downshifting too soon into turn 9 at thunderhill....hopefully someone who understands better can clarify

bigmac

My 90 S4 (2.54 rear) auto (chipped & RMB) would easily spin the stock 245/16's on full throddle starts, small chirp with 275/17.
Come to Sharks in Hell for some comparisons. Mac

michaelathome

I am not the best one to try to describe this I am sure however the S4's have mappings to tell the car at what speed and rpm to shift at as well as fuel control. I think that you hit the nail on the head Charley.

The parallel "kickdown" if I understand it correctly tells the car to run the car on the "Wide Open Throttle" map for shifting. The car will shift later in RPM's than the standard map and get you into the HP available around 4-6000RPM.

Not sure if that helps, again I know that someone can explain it better.

Michael

928ntslow

I did several of the mentioned bolt on's to my 82 and the best/most bang for the buck, was the combination of the high stall converter with the kick-down switch. Cost approximately $250 since I did all the work myself. Gave the car a new life!!!

buskey

Hi guys,

I've just picked up my first 928 S4, been strictly a 944 guy up to now but always had an eye open for a great Shark deal. Thanks for all of the great tips and suggestions. Of course, first thing I do is begin to look at performance mods to "enhance" my driving experience.

Can't wait to install the x-pipe, high flow cats and kick-down switch. Thanks to your advice, going to pass on the RMB and perf chip for now.

Let the modding commence!