Are rolling roads just for bragging

[obi_waynne]

I wondered what your thoughts were on rolling road sessions.

Are they just for bragging rights or do they serve a more useful purpose. So as not to sway this discussion I'll post my thoughts up later on.

So what is the point of having a rolling road session and getting a power graph printed out? Incidentally how many of us have used/got a rolling road report for our cars?

 

[turbonutter69]

I haven't had my car done but I took my mum's Scoob for a dyno session. But she only had it done because she'd just had Scooby clinic put a new clutch in and the dyno run was a freebie.
If your serious into tuning then they are a must but in most cases I think it is bragging rights.

 

[Prince]

I've never had my car done, but I think it's a good tool for finding out what power your car is putting out. I intend to put my Civic on a dyno after I have an engine conversion done, and then again after any major work.

I wouldn not put a car on a dyno if it has had no major mods done, or was completely standard (unless it was fairly old).

 

[CitizenErazed]

I dunno if anyone remembers my driving torque thread but I'd put my car on to see where my main power bands are and peak torque, it's useful information for taking the car onto the track no?

 

[Munday]

Useful for mapping and checking fuelling only IMO

Power runs can be waaay off and comparing different runs on different days on different rolling roads is pointless

 

[obi_waynne]

I agree CitizenErazed. Knowing where your power bands are helps you to optimise your gear changes.

No matter what fuel/atmospheric conditions prevail the peaks and troughs will always come at the same rpm they just might be a little higher on good days.

 

[pgarner]

Bragging rights for most people as every dyno will give you different readings depending on how they use and set them up.
however if your serious wanting to get the best from the engine then it allows you see where the improvements can / have been made during mapping - ie smoothing out the troughs and peaks. this will alow you to get the best map avalible before taking it out on the road / track to trial

 

[lutonmatt]

have never put a car on one before but when i get my new trans am it will be one of teh first things i do so i can get the bhp it is running at now before i do some mods
all going well i want it kicking out about 600 bhp by the end of the year but will be going on monday more then time if i can get a few bits cheap then it will be sooner

but want to know what its doing now then as i do stuff to it

 

[old-git]

If you are serious, then setting car up on a rollling road is an important part of getting the most out of your car.

1, Engine on dyno for running in and basic mapping.
2. Rolling road to set engine up in a more realistic setting (using car's exhaust, cooling system, air flow restrictions, etc.). A lot of issues will come to light at this point.
3. On track fine tuning.

 

[digital solutions]

i just bought this bit of kit, the g-tech pro ss, which gives you as it states in the manual, a true reading of current bhp, this is due to being done on a track or a road (being careful of speed ofcourse) it calibrates itself whilst in 2nd gear( which means no speeding, just noise) all you do is take it to 4k revs press a button, then the same at 2k revs, then drive drive normally or how ever you want to! and it records bhp, 0-60 time, g-force. the only thing is, is that it cost a couple of hundred quid and i saw on the web today that theres an app. on the i0phone that does it to for about £8. typical!!!!

 

[RobBentley]

Tried to run mine on one... given it was a freebie when I had the remap done, but getting an accurate reading was impossible due to the horrifically long gearing of the car.. amongst other things.

 

[pgarner]

Rob you should be able to do yours VAGCOM. would need to have a look and find what engine group your looking for but its a case of turning the torque from Nm to Ftlb then coverting this to HP. im trying to achive something for the carputer that gives me real time readings for some things


i guess the gtech runs off gps speed ?

 

[old-git]

i just bought this bit of kit, the g-tech pro ss, which gives you as it states in the manual, a true reading of current bhp, this is due to being done on a track or a road (being careful of speed ofcourse) it calibrates itself whilst in 2nd gear( which means no speeding, just noise) all you do is take it to 4k revs press a button, then the same at 2k revs, then drive drive normally or how ever you want to! and it records bhp, 0-60 time, g-force. the only thing is, is that it cost a couple of hundred quid and i saw on the web today that theres an app. on the i0phone that does it to for about £8. typical!!!!

Hmmm, I think I would take the results from an iphone with a LARGE pinch of salt.

 

[RobBentley]

Rob you should be able to do yours VAGCOM. would need to have a look and find what engine group your looking for but its a case of turning the torque from Nm to Ftlb then coverting this to HP. im trying to achive something for the carputer that gives me real time readings for some things

Yeah - I know, and i've already got the relevant calculations here in an excel spreadsheet. I've just never got round to actually doing it!

 

[HDi fun]

Thre are so many factors that influence the final numbers. Even if we ignore the margin for error in the RR equipment itself it's unlikely that you'll get the same numbers even twice in a row with the same car on the same day. RRs serve a better purpose for tuning when multiple runs can be made whilst tuning a car.

It's trends that we should look for, rather than absolute figures.

 

[Sid447]

Useful for mapping and checking fuelling only IMO
Power runs can be waaay off and comparing different runs on different days on different rolling roads is pointless

A minority I would think,

Use them for what they are, as a valuable tuning tool that is certainly repeatable to within 5hp every-time when the operator knows what he's doing.
Munday, I agree with your initial sentiment; though as far as different readings on different days....a dynamometer has a correction factor that is part of the tuning tool.
So that everything is corrected (certainly in most modern dynos) to either J607 or the European equivalent (ECE/DIN/ISA) which is virtually the same, or the newer J1349 standard which would read about 4% lower than J607 and it's equivalents.
This way when an engine, for example is prepared by a workshop in a sub-zero climate it can be compared to an identically built engine, built to the same specs by another shop in a desert climate and they would show identical power curves.
Then they'd be able to send the engines they built to each other and then dyno'd again to the same standard correction & show identical power again.
It can be done if good standards of control are adhered to.

Though it all starts to get confusing when different types of dyno are used. As the USA mainly use inertia dynos (Dyno-Jet and Superflow) and EU and a lot of other countries use the eddie-current type and there can be between 12 and 20% difference even with proper control of the correction factor being applied accurately between these types.

If a person were to make use of a dyno, it is best to stay with the same dyno and input programme each time, as then the value of it when making modifications becomes particularly helpful because it will show the differences you've made to the car faithfully this way.
Comparing results from different dyno's is where most of the confusion comes from as correction factor with quite a few shops that are aware "horsepower sells" think up their own versions of correction factors that are more closely related to marketing than reality.

 

[obi_waynne]

I guess that is the placebo effect @Sid447 how many people think there mods give them an extra 40bhp when in reality they are only getting another 20 or so!

Dynos are useful for before and after comparisons but little more IMO due to the widely different setups and results shown!

 

[old-git]

A wheel dyno is essential for setting up and extracting the full potential from your vehicle. However, done properly this can take hours and cost hundreds.

However, even just having a power run done at a show will give you an indication as to how out of tune your engine is.

Stick to the same dyno and operator (and similar weather conditions) for subsequent runs if you want to be able to compare results in a meaningful way.

 

[SLEEPER]

If your car is highly tuned a dyno is the best place by far to map it . Thats unless you do it on the road with a laptopd which gives its own problems.

For me it isnt a question of bragging rights and whilst it is true that the conditions do change using the same dyno will give readings which are comparative which is all you need. This means I can say for example how much more (or less) power I have with say a larger intercooler.

It also isnt all about how much bhp. a dyno enables tuning across the whole range so you can have the power spread you want.

just read OGs post i could just have said +1

 

[TCJBOLDIE]

If your car is highly tuned a dyno is the best place by far to map it . Thats unless you do it on the road with a laptopd which gives its own problems.

For me it isnt a question of bragging rights and whilst it is true that the conditions do change using the same dyno will give readings which are comparative which is all you need. This means I can say for example how much more (or less) power I have with say a larger intercooler.

It also isnt all about how much bhp. a dyno enables tuning across the whole range so you can have the power spread you want.

just read OGs post i could just have said +1

I agree with this and have found a reliable tuner and always take the car to him after any mod/upgrade BEFORE I track it as the AFR's (air fuel ratio) may need a tweak/fine tune in some part of the rev range as it IMO be more likely need more fuel as do not want it to run lean and detonate.
IMO this is important if you are increaseing the boost as well as checking the D C of the injectors to ensure that they can supply the fuel required for the power levels of the motor.