I have stock headers, H-pipe, stock resonators and RMB. The sound is awesome at 4k rpm. Just ask anyone at Watkins Glen last Friday on our parade laps through town and the old course. When my wife and I were walking through town later I had a couple guys commenting to me on how sweet it sounds.

Anyway, with the small backfires when rolling on decel, would a RRFPR (rising rate fuel pressure regulator) help?

 

The holy grail of sound and speed....
I had an '85 s 5 spd., lopped rear muffler off (this was before RMBs were around) and lost bottom end response. Replaced the center resonator with a Brullen, no change.
Added two hi flow mufflers to the rear, still very loud but lower response returned.

On my 83 Euro-
Dual-pipe test pipe to 928SP Afterburner exahust...WAAAY loud. Strong top end. Installed dynatech venturi cone after muffler, took a couple Db off but still too loud.
Went to Ott X-pipe to OEM cat-back. Still too loud, not much change in performance. Installed Dyna-tech inserts, took a few Db off, but not enough.

Currently have GT cats, Ansa 32V dual-pipe center section and new OEM Euro dual-in rear muffler- its louder than cars with stock exhaust by a bit, has good responsiveness.

Ideally I'd like to go to a better x-pipe and cats and install my '85 manifolds...the latter is a matter of time and equipment (manifold swap on back with no garage is not looking fun) and the former is a matter of not seeing data for the X-pipe's performance on 16V cars...the Euro cams are a whole different ballgame.

BTW- the benchmark I used for 'too loud' was my recollection of the sound of my '67 Tripower GTO with headers and glass packs......louder than that was NFG. I don't know whether its the aluminum vs cast heads or the extent to which the cylinder is shrouded or what, but the 928 motor passes a LOT of noise!

What I think I would LIKE to do someday is get a good x-pipe with performance resonators/mufflers, 86.5 center sections and RMB. I like my current sound level, but I hate the idea that the GT cats are robbing some power...Hopefully the fact that I have a 4.7L and they were designed for 5.0L flow mitigates that to some extent.

 

"Did you add two Borla mufflers or just one? Wich one did you use?"

This is what a single 3" Borla XR-1, no cat, 'RMB', 3" single exhasut 16v 928 sounds like:
http://www.putfile.com/media.php?n=928InCarVideo
(car is very loud in person, turn volume up)

Highest Rs achieved in video is about 5500(1-2 upshift).

Pic of system:


Complete system weight: 22lbs
Total system cost: about $500

 

Sounds similar to my H-pipe/resonator/RMB '87's set-up. Only mines faster, hahahahahahaha...........

 

Weissach:
My exhaust is a Y pipe 2.5" (where the cat use to be) then connects to the Borla SS pipe 2.5" then a resonator and finally the oval muffler.

m21sniper:
That sounds like my exh but without popping on deaccel. Does the 3" tubing drown out the radio? What muffler are you using?

 

HincheCliffe- "Sounds similar to my H-pipe/resonator/RMB '87's set-up. Only mines faster, hahahahahahaha..........."

You live pretty close to me. Care to put that boast to the test of asphault?

Unless you're SC'd/Gassed it's a pretty safe bet i'd beat you soundly in a 1/4 mile run. My Shark is by no means stock.

Ask Lance.

I ran his 83 Euro when he was running a 65shot of nitrous and took him 2 runs out of 3. From a standing start it wasn't even a very close race( i beat him by 2 1/2 or so lengths), so the next two runs we did rolling starts to even things up a little.

Do not underestimate the "UPS Shark".

 

"m21sniper:
That sounds like my exh but without popping on deaccel. Does the 3" tubing drown out the radio? What muffler are you using?"

LOL, note that in the beginning of the vid you can hear Ozzy Ozbourne playing on the CD player...until the moment i hit the go-pedal.

I'm running a 14.5x3" Borla XR-1 Off-road racing muffler.

 

Cool Thanks, little too loud for me,
and my amp is 300 watts..........

 

Huh, so watcha got inside? What times are you running/dyno results are you seeing?

 

I ran a 13.67 last year, and have since shaved about another 100lbs of weight from the car(plus added wider rear rims). I figure it's probably good for about a 13.5 in race trim now.

Probably a high 13 in street trim.

Never dynoe'd it(that's why god invented dragstrips, lol), but according to the ET/horsepower calculator and based on an estimated weight of 3300lbs(with driver) that works out to 332crank HP(255 RWHP).
http://www.race-cars.net/calculators...alculator.html

Based on my trap speed of 103.1mph this calculator: http://www.ajdesigner.com/phphorsepo...horsepower.php
states a crank HP figure of 282.25 hp.

So 282+332/2, and you get an avg. crank HP of 307, which based on the known times of a wide variety of vehicles in that power/weight range(such as the new Rustangs and LS-1 F bodies), strikes me as being very close to reality.

 

So the 'by no means stock' part is basically lightening, exhaust and intake hoses?

 

Cool Thanks, little too loud for me,
and my amp is 300 watts..........

 

"So the 'by no means stock' part is basically lightening, exhaust and intake hoses?"

I have no idea what all was done before i owned it. I'm not the original owner, and i'm not about to dissassemble the engine just to satisfy my curiosity.

Sorry, that's about all the help i can give.

Known mods are 3" runners, full borla custom off-road racing exhaust, 85' headers, RRFPR, custom built racing radiator, 50 degrees total advance, 245/45/16 tires on 16x8 rims and modified 4 speed transmission(always starts in first), Bilstien/Eibach suspension and about 350lbs of weight savings. The radiator, RRFPR, and headers were already in place when i got the car.

The 13.67 was accomplished with 20psi in the rears and 50psi in the fronts with an 1800rpm launch after an extended burnout to heat the tires.

Beyond that...your guess is as good as mine.

The 'by no means stock' refers to the ET.

No 83 928S ran a 13.67 1/4 mile, nor did they come close to that ET. So it is clearly 'by no means stock'.

 

Most S4's stock run a 260-270 RWHP on a dyno and they are 316 at the crank, supposedly. So figure you're just under that, which would make the 307 crank sound about right. Unless you'r car is a lot lighter than mine, I'd say we ae fairly even. With my exhaust I assume I get maybe 280 RWHP, so close to 325 crank?

 

Thanks. Wasn't trying to be critical or argumentative, was just interested in finding out whether you were being a little cagey or not.

I had a couple of similar experiences. My first 928 was an '85 32V, which appeared to be pretty stock except for twin Jacobs ignitions. It was really impressive in power delivery though, capable of breaking traction on dry roads in second and third when WOT was hit from a roll. Unfortunately *something* happened and that went away- no one was ever able to diagnose/explain..

My current '83 Euro was also extraordinarily robust as a couple of others can attest. It was also having 'issues' when it was performing that well. It had a pretty open exhaust..and one of the problems was that the distributor was screwed. It had a penchant for going off the chart with spark advance, was eventually found to be shorting out. So I think part of your performance might be from being able to sustain the 50 degree advance. I know some of the racers with my old-style mechanical injection saw gains from adding a few degress, maybe thats also the case with your car (and the updated fuel delivery).

Mine is running OK now, I'm toying with the idea of trying to start creeping forward with the advance too....its running better than it used to in many respects but not delivering the power...so you have a good philosophy, enjoy the fairy dust that gives it big *****, and don't mess with it too much.