Who needs a Shrick???

[Andy Brookes 0]

wow wow wow!!! Kev, I did say I didnt want to start a fight!!!

 

I just thought that your explaination didnt provide enough proof with the circumstances that you put forward, the length of time etc etc between rolling road days at AMD and Stealth. Davidwort's explaination has more weight and supports yours to a certain extent. Dodgy old subject the rolling roads.

 

Just think that that kind of allegation needs to be handled with care on a forum like this, otherwise the the forum can suffer. Thats all. Didnt mean to upset anyone.....i'll go back to being quiet!

 

Cheers Andy

[Mike Edwards 0]

Maybe I should take my remapped VR6 along to Stealth for the VWCCGB Rolling Road Day, rather than the G60?

 

Then we can compare figures.

 

Mind, my 16v on Stealth's rollers made 154bhp when it ought to be making 136bhp...

[dr_mat 0]

The Mike Edwards touch.. How do you do it, Mike?

It's the nitrous isn't it? Go on, admit it! ;)

[Mike Edwards 0]

In this case, it might just be napalm...

[Kevin Bacon 5]

Napalm, LOL. I think Asims runs on that too as it's giving 212 as standard :shock:

 

Brookesy, yeah sorry if I appeared arsey, not intentional. I don't think doubting AmD's figures on here will cause any major ripples for them or any forum visitors. We all know our cars well enough to know if an extra 20bhp from a simple mod translates to more urge on the road, so a certain amount of salt needs to be taken with the readings.

 

Maybe taking the average of 3 different dyno results might give a better idea.

 

K

[Scott 0]

Have always found Dubsport rollers accurate myself.....

 

1.8 16V rollered at 138bhp

 

2.9 VR6 rollered at 192bhp

 

Not Bad! :lol:

[emax 0]

Another way to look at it is what is the "at the wheel" figures that you got? Does the difference at the wheel look right when compared with the difference "at the flywheel"?

 

Here is an interesting articles about rolling roads:

 

http://www.pumaracing.co.uk/trans.htm

http://www.pumaracing.co.uk/setup01.htm

[dr_mat 0]

Interesting reads, definitely.

Re-looking at the rolling road results I got from Stealth, my completely-standard-but-Schricked VR6 put out only 151 bhp to the wheels. Now in the absence of any evidence that suggests I have excessive transmission losses (I don't have dragging brakes, I don't have dodgy wheel bearings, I don't have a dead gearbox etc), I have to assume that's an accurate reflection of the engine's output.

 

While it's *nice* to think my VR is a 201bhp car, I'm MUCH more inclined to think a 120k miler is likely to be around 5-8bhp DOWN on "factory" output, than 10-11bhp UP, frankly... (Knowing, of course, that the Schrick adds little or nothing to the top end power.)

 

Of course, that doesn't mean I won't be telling all my mates I have a chart that says "201.1"... :)

[Kevin Bacon 5]

LOL, 151 bhp sounds very unimpressive!

 

Which makes me question how the Americans seem to get such high wheel hp figures all the time, from similar mods to what we do.....and they're 100cc down???

[dr_mat 0]

But it makes more sense.. Even Asim's giant-slaying VR6 is just around about factory standard output, going by the info in the above link, from the wheel figure he posted a few weeks back.

 

Good question about the Vortexers tho. Dunno how they get such claimed WHP...

Or is it just that - "claimed"?

[emax 0]

I have had my car rolling roaded twice since I have owned it and have a dyno plot from AmD with the previous owner.

 

At AmD, the car made 199bhp and 199lb/ft IIRC

 

I had the car rolling roaded (not at AmD and pre-schrick + remap) it made 192.5bhp and 183lb/ft and 158bhp at the wheels.

 

on the same rolling road, after the remap and schrick, it was up to 209bhp and 196lb/ft but the "at the wheels" figure only increased by 3.5bhp to 161.5bhp.

 

I find it interesting that, despite a significant increase in the "flywheel" figure of 16.5bhp, the increase "at the wheels" was only 3.5bhp.

 

I don't know how the "at the flywheel" figure is derived to be honest but I don't think it is worth the paper it is printed on.

[dinkus 10]

The only way to be sure is to get the car tested on the same rolling road before and after the mods. Then only go by the wheel hp figure.

 

The wheel hp figure is what the rolling road actually measures, so that's hard to fake. You then divide it by where the moon happens to be and how many letters are in the day of the week to get the crank hp rating, so it's always going to be off.

[PhatVR6 0]

just take it down the 1/4 mile.

 

time is a constant.........(and don't getting all stephen hawkins on me by saying it's not)

[dr_mat 0]

Just doing some maths..

Following the stuff on the puma racing site, I reckon that a Corrado VR6 (Cd 0.32, frontal area 19.54 sq ft, top speed 145mph, weight with person 1270kg)

requires 14bhp for rolling resistance, plus 130bhp to overcome wind resistance at 145mph. So it only actually requires 144bhp at the wheels. Which kinda implies to me that something is wrong in that maths, I'd say, either that or the gearing on the VR is wrong, and it would actually top out faster than that with a taller top gear (or a shorter one).

 

Given that most people's are recording 151 - 160 bhp at the wheels it implies those figures are out...

[Kevin Bacon 5]

1270Kg with person? A very skinny person!

 

With a person of average weight (75Kg) and a full tank, you're well over 1300kg....

[dr_mat 0]

Probably true.

Still, that doesn't make a huge difference - the biggest effect is wind resistance by far.

You need an extra 6bhp to make it from 143 to 145 mph, for example!!

[dinkus 10]

just take it down the 1/4 mile.

 

time is a constant.........(and don't getting all stephen hawkins on me by saying it's not)

 

Ah but time slows down the faster you go :D

[corradovr6sc 0]

LOL, 151 bhp sounds very unimpressive!

 

Which makes me question how the Americans seem to get such high wheel hp figures all the time, from similar mods to what we do.....and they're 100cc down???

 

Americans calculate whp as a 12.5% loss through the transmission so a stock 2.8 vr6 with 174 hp would produce 152 whp.

 

Transmission loss varies between cars but if they use this 12.5% figure based on crank hp they always end up with a high whp figure.

[davidwort 0]

...The wheel hp figure is what the rolling road actually measures...

 

well, no actually, it's torque at the wheels, everything else is calculated/guess-timated.

 

By far the most interesting data I've had is plots of my car on the same graph as others run on the same day, especially very similar vehicles, e.g. a bog standard 2.0 16v against my 16v with my ported KR head and cams on a 2.0 bottom end, you could clearly see the characteristics of the higher lift cams and the constraints of the catalyst equiped 9A engine.

What would be very useful for rolling road days is another benchmark, e.g. stick my bog standard 1.6 16v golf4 on there. Would some of these VR6's actually perform as if they had twice the power of the golf? (- it also weighs almost exactly the same as a C. 105bhp, about 10 sec 0-60 and nearly 120mph top speed.)

 

David.

[PhatVR6 0]

well, I'm not arguing about BHP figures here, but I can tell you for a FACT that my car ran a SH!T load faster with my mates AmD chipped ECU than it does with the stock one. A notable, real difference that you can physically (not phycoligically) feel. I'd estimate easily 15bhp more than how it runs now. and I'm prepared to find out at a rolling road day soon. I'll do a run with each ECU and let you know.

 

as for dubsprots rollers...don't forget my standard 8v put out 137.6 BHP there earlier this year....... :roll:

[Storm 0]

Just doing some maths..

Following the stuff on the puma racing site, I reckon that a Corrado VR6 (Cd 0.32, frontal area 19.54 sq ft, top speed 145mph, weight with person 1270kg)

requires 14bhp for rolling resistance, plus 130bhp to overcome wind resistance at 145mph. So it only actually requires 144bhp at the wheels. Which kinda implies to me that something is wrong in that maths, I'd say, either that or the gearing on the VR is wrong, and it would actually top out faster than that with a taller top gear (or a shorter one).

 

Given that most people's are recording 151 - 160 bhp at the wheels it implies those figures are out...

Washing machines are generally white, roads covered in Tarmac and persons under the age of 16 go to school. Policement wear Black uniforms, hang on this is meaningless twaddle. :roll: :)

[dr_mat 0]

You don't wanna know, you don't have to read it.

[Kevin Bacon 5]

LOL.

 

At the end of the day, RR figures are academical if the car feels good and strong on the road. I beat a Corsa 1.2 on the way home tonight, so I'm happy :lol:

[Storm 0]

LOL.

 

At the end of the day, RR figures are academical if the car feels good and strong on the road. I beat a Corsa 1.2 on the way home tonight, so I'm happy :lol:

Absofeckinglootley - If it feels good it is good.

[Joe M 0]

Just doing some maths..

Following the stuff on the puma racing site, I reckon that a Corrado VR6 (Cd 0.32, frontal area 19.54 sq ft, top speed 145mph, weight with person 1270kg)

requires 14bhp for rolling resistance, plus 130bhp to overcome wind resistance at 145mph. So it only actually requires 144bhp at the wheels. Which kinda implies to me that something is wrong in that maths, I'd say, either that or the gearing on the VR is wrong, and it would actually top out faster than that with a taller top gear (or a shorter one).

 

Given that most people's are recording 151 - 160 bhp at the wheels it implies those figures are out...

 

Depends what rpm and how much power the engines putting out at 145mph though, the engine might have passed its peak power and started dropping at 145mph. :?