Rolling Roads Results

[Dizeee]

Just thought I would introduce a new topic to the family...


Would be interested to see what we have on here in terms of official readings. Its a good family, so, we should be able to share our figures! But we all have stories. Here's mine.

I was always petrified about RR the car, but in the presense of some good PH friends I did it. I always knew the car was strong by what it can do.

But - pub talk. Say no more.

And I know the bhp/tonne can't be that embaressing, only by driving it. So I had faith. I knew the car, I had confidence. But I didnt "know". Does that make sense?

I expected what I was told by the tuners. "At least 270bhp" they said.

I went to Vixpy1 - PH member and Surrey RR director....


http://i47.photobucket.com/albums/f155/jamesdennis556/Car/DSCI0003-6.jpg


It was a warm day and I had a heck of an audience. Most could not believe my quote of 270bhp, but with my Remus / EDS map / 100 cell Cat - I was quietly expecting + 280.


"But it's an Astra".... etc etc


I made a bizarre reading for a stage 2 VXR - only 266bhp. Most see minimum of 280bhp.

However, it was summer, and I dont have any sort of intercooler. I was still very unhappy with the 266 as it was very low.

I knew what the car did "on the road" and I decided on a 2nd opinion from long term VX specialists Regal. I booked it in with a "problem" based on figures. I knew there was no issue but needed a 2nd opinion.

Regal having received the car stated it was a more than healthy Stage 2 VXR. Tests done / plugged in / RR's and all good. It was later in the year, so coldeer air now. Car has also benefited from a K and N, and Iridium Plugs since then.


http://i47.photobucket.com/albums/f155/jamesdennis556/Car/DSCI0005-2.jpg


http://i47.photobucket.com/albums/f155/jamesdennis556/Car/DSCI0003-8.jpg


http://i47.photobucket.com/albums/f155/jamesdennis556/Car/DSCI0006-1.jpg


Even managed to record the golden stats:



http://www.youtube.com/watch?v=8FMbqPHceXs











Whats your story?????

[alfamale]

Dyno figures vary so much between equipment its almost impossible to get a benchmark, we all want to see big numbers and dyno operators tweak them on the high side to keep everybody happy.

[Ben-san]

Good work Diz... I trust you had the seats down? :D

I do agree with the above - figures vary so much that I don't quite know where to put my trust. It becomes more apparent when we compare dyno systems, like the difference in figures between Dyno Dynamics and Dynapack for example. The US call the former 'The Heartbreaker' because it reads lower, sometimes as much as 100hp.

And then, there's the dyno operator. How he calibrates his dyno or whether he factors in things like vehicle inertia is anyone's guess. Plus, tranny losses are mostly guessed at. One way to get around these variables is of course a Bench Dyno - but that's ridiculously expensive and quite frankly impractical for most people.

Still, it's really a bit of fun for me, and I just like to know what the car's capable of.

[Dizeee]

My low figure was achieved on Dyno Dams... didnt know they were known to read low, makes me feel a little better...

[Ben-san]

My low figure was achieved on Dyno Dams... didnt know they were known to read low, makes me feel a little better...

No, they don't read low dude. The Dynapack reads high...

[BigShow]

I've done 70+ dyno pulls now and most of those were done on a hoffman dyno owned by 1320MINI, they dyno'd me when my Cooper S was stock at 163 bhp and my mates Elise 111R at 191 bhp so I know they're accurate and they take the utmost care with the car.

Also, used Surrey & AMD giving varying results each time but 1320 always hits the nail on the head.

Last dyno day I hit 282.6 bhp and 214 lbs ft torque then backed it up at the strip running 13.61@105.6 mph and using the VBOX running 0-60 in 5.6, 0-100 in 12.6 and 30-70 in 4.2.

Dyno's are great but you know you've found a good one when your Santa Pod results back it up.

Weird thing was before John Barker from Evo drove my car at Bedford I had the stock cat back exhaust put on to ensure no noise reg issues and dyno'd again and lost 10 bhp taking it back to 272. Asked John to guess the power and he thought about 265-270 bhp!! I want his experience!.... His butt-dyno is the most accuarate one I know of :D

[bruce fielding]

I HATE dynos.

When they're used properly - to tune an individual car and eliminate flat spots - they're great

When employed for bragging - worse than useless. I know of no one who has ever been anything but disappointed.

[Angelis]

I've had my Ferrari 348 on both a rolling road and a Hub dyno.

One thing I've found is that Ferrari owners don't tend to put their cars on a Dyno as their figures are usually down on the factory figures provided. Then again, most people reckon the factory massage the figures anyway. :p

I also recall reading an article in EVO magagine where they dyno'd a 599. The figures were way down, so they changed the wheels/tyres and got an extra 40bhp!!!

My 348 is supposed to have 320bhp stock. At the time it was also decatted (worth an extra 5bhp), K & N air filter and a sports exhaust. When I put it on a rolling road it only had 304.8bhp at the crank. As Bruce said above, very dissapointing.

After doing an engine out cambelt service and the cam timing (amongst other things) it was put onto a Hun Dyno at TDi in Lakeside Thurrock. This time I had 281bhp (with sporst cats) at the hub which worked out between 332 to 352 bhp depending on the transmission loss (15% to 20%).

To be honest, the additional figures were more of an ego boost than anything else. However, it was only until a few months later when I was at an Airfiled Day that I really noticed the difference. I was 5 seconds faster per lap.

[Marcellus]

I think a big issue (certainly with the ST) is that cars are too damned clever..

In the example of the ST (in case people didn't know);
Issue #1
> it has traction control
> traction control has a sensor on each wheel and if one wheel starts to move at a different speed from the others then it throttles back the power to that wheel until it meets parity with the others.
> On a rolling road you strap two wheels to the kit and run the other two in the rollers.
> The magic voodoo thing called the ECU thinks the front wheels have lost traction best ease it back a bit!!
> hit the traction off button and it still doesn't 100% turn off (Ford scared of litigation) so it turns it down to about 20% active.
> if you persist at this 20% and turn the wheels it will eventually think it's broken and disengage!

Issue #2
> It's got a turbo, not the biggest but it's there
> Turbos need to be kept cool to run at their optimum
> The ST has a small intercooler as standard (Ford did this to reduce the power)

The test process
> Rolling roads require you to run a car upto it's limit in a gear and then lift off and it measures all the result, does some voodoo magic and comes up with a magic number.
> Often to ensure accuracy you should repeat this process a couple of times to ensure consistency and therefore accuracy.

Results
So, you have to run the ST in 1st until the computer thinks that the traction control is buggered and then start your 1st run.

By this time the ST has done a run the intake temperatures are getting warm.

The engine senses this and to prevent potential damage tunes down the engine therefore the figures will never really get to where people want/think they should be.

Over the years of working with the Tuning companies for the ST we tried all things (larger intercoolers, nitros sprayed onto the intercooler, stupidly big fans) but never got a truley satisfactory result.

What you're trying to recreate is a car driving from 10mph to 110mph as quickly as possible and the resultant airflow, not just into the intercooler but under, over, round and through the whole engine bay.

So I suspect anything with the engine in the back, anything where the there's a turbo and anything where the manufacturers have had to compromise design or quality for the sake of cost/aesthetics will have the same issues!!

[Dizeee]

Most of all that is no different with the VX owners either.

Its al very interesting when it seems to spread to the Ferrari owners aswell. Its amazing as people have sold cars solely down to dyno figures.

It makes me feel a whole lot better when I see that I am not in my own with issus surrounding figures etc.

[Marcellus]

Porsche driver too IIRC......rear engined...in fact most cars that are designed for the roads as they've had to compromise the design from pure performance into budget, driveability and appearence...

After all not many people would drive a car with massive radiators exposed at the front.....

As Bruce says Rolling roads are usefull for tuning and measuring the change/improvement to see the benefit of a versus b but not for the actual number.

IIRC engine manufacturers bench test engines (without the rest of the car/engine bay) to get the numbers and then go from there.

[chevy-stu]

On the odd occasion the figures do add up, at Vixpy's couple of years ago now, some peoples cars did actually achieve what they expected..
(might be good organise another one if anyones up for it)

Interesting info with the traction control thing on the ST's, do all modern cars with TC do that ? I know any turbo car will struggle to stay cool to make the power, do you notice a difference in power summer to winter, cos I do in the VR4.

I'd love to get the chevy down to a rolling road soon, supposed to have genuine 460 BHP, but I'm guessing this is on a generous 'american' bench dyno, with no power steering or alternator pulleys sucking the power, no guessed transmission losses and at ideal temps too..

[Marcellus]

STu - yes tehre is a noticable difference summer to winter in the ST!!

As for the TC....it was explained to me that all the manufacturers are so scared of litigation that they make it very difficult to turn it off 100%!!

That said..I have driven a few cars where you can switch off the TC and get some very nice power slides going on so when the TC cuts in I couldn't say!!

[Dizeee]

Also notice a big difference in performance depending on air temp. A hot summers day can the car be quite lethargic, however a crisp winters morning the car can be almost unmanageable.

[Harsh]

a bit like me really!

[Gaz]

I didn't realise the VXR didn't have an intercooler!

I changed mine after my OEM one was badly damaged by corrosion and debris, I replaced it with a direct replacement and my Vmax results shot up from 153mph to 161mph in similar conditions at bruntingthorpe, it also felt a lot stronger in the 2nd half of the runway from the last time round.

As good and honest SRR are, I prefer DSA have they have better cooling facilites and it's easier to get the cars on and off, and given that a lot of race teams use them through choice they are good enough for me.