good to know! if anything the tach gets slow up top

 

This run included going down a hill I must add, I was experiencing something similar to you with 100mph seeming like the limit. I regret not shifting into 5th, I'm almost positive I would've gotten another 5mph. When I did this my plugs were very new, but I want to corksport headerback exhaust, new wires, and fuel filter and go give it another shot and shift into 5th!!!

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top gear tested a brand new s4 and got it to hit 133 i think

 

134mph was the quoted top speed for the S4 in that clip from Top Gear, as they were pitting it against a Porsche 944. The clip is on youtube, but I'm just too lazy to go dig it up.

As for the OP's problem, that sounds like a clogged fuel filter to me. Haven't recently been into the standalone section, but I'm pretty sure that fuel needs increase somewhat exponentially compared to engine rpm and horsepower. Sorta like how to go 150mph, you only need around 270hp but hitting 250mph requires another 730hp (referenced in the Veyron top speed test by Top Gear, also on youtube).

Before doing the 5-speed swap, I had some jackass in a BMW think he was hot **** by staying on my *** for way too long. So I let it wind out and 100mph was roughly 3300rpm in a stock S4 GXL automatic in its top gear and it was BEGGING to go faster too (even with disconnected aux ports). At 100mph, I let off and let the douche go. A couple miles down the road, he was on the side of the road with the highway patrol *insert Nelson laugh from the Simpsons here*

 

Pretty much been said, but a healthy stock(ish) na, S4 or S5 should be good to roughly 130mph (230kph). I'll hit 200kph lap after lap on the front straight of the local track - 210k is the most I've personally had mine to. Hitting a wall at 100mph would seem to indicate a problem with fuel, spark, or aux ports or VDI function. Or if the cat is still on it, maybe it's clogged or broken down. My dd Passat had a partially melted cat, it cut significantly into mileage and top end power, even though I didn't know it until I replaced it. Exhaust leaks can have a big impact on power with na rotaries as well.

 

+1 on checking the exhaust and cat as well. my exhaust was full of holes when I got my car, and it was significantly faster after I welded it up (temp fix until $$$ for new exhaust). If its like hitting a wall though then I would suspect it to be more of a fuel or spark problem.

 

fastest ive gone in my t2 is 130, got scared after that (can't afford to get a ticket right now)

fastest i could go in my buddies s5 n\a before i let off was 110

maybe it's a werid s4 thing?

 

are you sure about that 270hp thing? my buddies s4 t2 with a street port + stock turbo could burry the needle (took awhile but it could do it) and he never dyoned it either everything was done with the butt dyno haha (guessing he had 230~250hp)

 

From my experiments on the dyno with my T2, the speedometer is within 2mph. By 8000 rpm (as read by the ECU) my s4 turbo tach reads anywhere from 300-500 rpm too low. The s5 n/a tach might be a little better because it goes up to 9000rpm.

 

THey were talking about the Veyron, a much heavier and bigger car. Its probably a lot less for us, but doubt we would make it to 250mph regardless.

 

Tell your Dad to slow down.