TTS Supercharger development for RS4

[PetrolDave]

I totally disagree with the drag strip being the be all and end all.
It's completely unscientific and tests the driver as much as the car.
I've seen plenty of high powered cars get screwed by a bad launch or bad change.
Same goes for 0-60, 0-100 and the Nordschleife.

As for a dyno - there was a link posted here recently that really went through the problems with dyno testing.

3-8k in gear test completely takes out many of the variables. Driver, tyres, etc.. Sure you still need to know slope and conditions but it's considerably more repeatable.

+1

[sakimano]

I totally disagree with the drag strip being the be all and end all.
It's completely unscientific and tests the driver as much as the car.
I've seen plenty of high powered cars get screwed by a bad launch or bad change.
Same goes for 0-60, 0-100 and the Nordschleife.

As for a dyno - there was a link posted here recently that really went through the problems with dyno testing.

3-8k in gear test completely takes out many of the variables. Driver, tyres, etc.. Sure you still need to know slope and conditions but it's considerably more repeatable.

APR's original launch of their RS4 supercharger dyno'd great. It did welll in 3k-8k pulls. It got to 60mph well even. However when it was tested in pulls and at the dragstrip by customers who paid $19,000 for the kit, it was found that the car was maybe 1 or 2 car lengths faster than stock in pulls, and 2-3 tenths faster at the dragstrip. It dyno'd 100+ whp over itself pre-supercharger however. A 100+ whp (say 120 bhp) gain should not equate to 1 or 2 car lengths in a quick 3rd-5th pull.

The problem? the tune. If running through the gears, you find out what the tune is all about. APR asked a competitor's tuner to make some adjustments to the tune, and he scrapped it and started over. When he did, the car ran 12.1 @ 116 mph at the strip full weight (vs. 12.7 @ 107)...and APR ran another customer's car 11.83 @ 116 with no backseat.

If you really want to look at a microcasm of your car's performance (an in gear pull for 8 seconds) you'll get a microcasm of how well the car is performing. I'd much rather have information on how the car accelerates in gear, as well as coming out of one gear to the next...and all through multiple gears. For you and I testing our own cars, sure the 3k - 8k pull is great. For selling a nearly $20,000 supercharger kit, it's not exactly ideal.

As for getting overwhelmed by the dragstrip...really? Have you been in an Audi with quattro? While it's tough to get a perfect launch, it's not tough to get a decent launch. WE're not RWD cars that get sideways with a bad launch and need to ease into each gear, and end up with 2.4 60 foot times. In any event, a bad launch like my tire spinning 2.0 second 60 foot times last Saturday is only going to add about 2 tenths to your elapsed quarter mile time in an AWD Audi. If you run a best of 12.9 @ 110 mph after 4-5 runs in a supposedly 600 hp car, it'll be obvious that something is wrong...and even a good driver is only going to get that into the mid 12s, but trap speed won't change much. Any good driver can put up a decent time, but more importantly we'll see their trap speeds and all of the data on the various points of the run. 60 feet. 330 feet. 1/8th mile. 1000 feet. 1/4 mile. If you can't launch like you would in a spirited run from a stoplight...and if you can't row through gears 1-4 without mis-shifting when you get 4-5 runs to get it right, I'd hazzard a guess that you should probably not be the one driving the car when putting information out for a near $20,000 supercharger kit. MRC would never let that happen.

[adsgreen]

Why don't manufacturers publish 1/4 mile times?

What could you screw up on a tube that would affect gear shifting?
The only thing I could think of is the bypass valve control but you'd have to be an amateur of the first class to get that wrong.

Not being antagonistic - genuinely curious.

[lengster1]

Im sorry but i cant agree,i could of easily gone further with tuning my b5 RS4 and gained better outright power,sure on a dragstrip and barstool it would of been great but straight line performance and outright performance are not what make a fast car from a to b.Its easy to drive in a straight line keeping a big boost high power turbo car on the boil but in everyday situations driving like that would be a pain and get you banned.Drag strip has way too many personal skill variables involved to be accurate,a top driver could easily get a good result from a stock car but sit in another driver and the same car could do a much worse time quite easily

[adsgreen]

I agree with turbos as big = better on the drag strip but not on the road.
But in the case of supercharges shouldn't suffer with that issue.

[Stoffle32]

Im sorry but i cant agree,i could of easily gone further with tuning my b5 RS4 and gained better outright power,sure on a dragstrip and barstool it would of been great but straight line performance and outright performance are not what make a fast car from a to b.Its easy to drive in a straight line keeping a big boost high power turbo car on the boil but in everyday situations driving like that would be a pain and get you banned.Drag strip has way too many personal skill variables involved to be accurate,a top driver could easily get a good result from a stock car but sit in another driver and the same car could do a much worse time quite easily

+1

Its not about Drag times
And in an AWD drive car the slightest bog can loose you a second when you cross the line.

[MB2]

Why don't manufacturers publish 1/4 mile times?

What could you screw up on a tube that would affect gear shifting?
The only thing I could think of is the bypass valve control but you'd have to be an amateur of the first class to get that wrong.

Not being antagonistic - genuinely curious.

I guess the main reasons are that most of the public don't know what a decent time is, just from the Fast & the Furious that a "10 second car" is quick & probably a lot of cars will even out over the 1/4 mile so it is harder to make a hot hatch sound quick next to a regular saloon, just as top speeds have pretty much evened out ? It would certainly be less arbitary than 0-60 which is much more affected by gear-shifts ie if can reach 60 with one change or 2 will make a "big" difference on a manual car. Bikes have always been measured by 1/4 mile times, probably for the opposite reason as they all hit 60 so fast (3-4 seconds) that is hard to differentiate whilst 1/4 needs more bhp/aerodynamics.

[PetrolDave]

Istraight line performance and outright performance are not what make a fast car from a to b.

Its easy to drive in a straight line keeping a big boost high power turbo car on the boil but in everyday situations driving like that would be a pain and get you banned.

Well said, and I totally agree with you.

[sakimano]

Istraight line performance and outright performance are not what make a fast car from a to b.

Well said, and I totally agree with you.

well...you guys know that MRC and TTS are selling a POWER ADDER right? THey're selling a kit, in this thread, that adds straight line performance. Why the heck WOULDN'T you want to see straight line performance test results?

Maybe we should take it to a car-show so someone can tell us how pretty it is. Then, we'll take the car to a skidpad and measure the lateral Gs it can hold. Next, we'll do a braking test to see how well the TTS supercharged car stops from 60 and 80 mph. Then we'll do some math and talk about engineering principles.

Then, and only then, will RS246 be ready to determine whether we should all buy the APR, TTS or JHM supercharger kits. You guys are right. All this talk of measuring straight line performance...what a waste.

[PetrolDave]

You guys are right. All this talk of measuring straight line performance...what a waste.

By George, I think he's getting the point... NOT!

Any incompetent idiot of a driver in an overpowered ill handling shed of a car can drive fast in a straight line, that's NOT what RS models are about - they're about a complete balanced package of power AND handling.

If you're only interested in stright line times, then you've wasted your money buying an Audi - trade it in for a Holden HSV or a Corvette.

[S4Player]

I agree that the rs4 is not about straight line speed BUT when talking about one with a supercharger strapped on then surely straight line speed is a topic of conversation? It's not the b all and end all but it is a factor, I disagree that getting a good time on the strip is easy because it's not, all IMO of course

[Rick_RS4]

so whats the 1/4 mile time then? lol

[adsgreen]

I do agree that when talking about power upgrades then talking about bends isn't 100 relevant.
You do have to be careful as an ideal drag racing car would be damn awful on the road (eg, solid rear axle, peaky high rpm power, soft rear suspension...etc)
However wrt to supercharger mod this isn't an issue.

I am struggling to see what you could do to an engine map that on the road /dyno gives 100+ whp with corresponding in gear acceleration improvements but then end up with a car at the drags trip no faster than stock with another car just having an exhaust and map completely destroying it...

Fi does change the launch as you've got way more low down torque... Could be that or maybe the clutch wasn't up to the launch and gear change method...

This does remind me of a quote from a racing driver when asked if his car had enough power "when I can leave smoking black tyre marks from the exit of one corner to the entry to the next *then* I have enough power"

[BlingBling]

Drag strip runs are a good indicator of power through the gears. You can have a pap start but still record a good trap speed. The time is a bonus part for dick waving but in the main the end trap speed is more important.

[adsgreen]

thats true but the trap speeds for the APR are well off too - makes me wonder if there was some losses going on from say a wrecked/duff clutch or similar.