Rolling Road argument (Car thread but sort of bike related)

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Hi Guys,

On another forum I occasionally frequent, there is a minor argument about fuel mapping on turbocharged cars.

Apparently the best way (according to the members of this forum) to build a fuel injection and ignition map for a turbocharged car is to have a passenger sit in the passenger seat with a laptop connected to the ECU and a pair of det cans (which I assume is some sort of knock sensor on a pair of earphones) and set up the car that way.

I find this strange, because as far as bikes are concerned, the only way to set them up after exhaust or intake mods is on a dyno. I've always been schooled with the idea that a Dynamometer is the only way to measure and set up fuelling. The Dyno can produce varying loads on the engine, and it can test the engine running through the gears (we all know there are different fuel maps for different gears on bikes, but what about cars?).

So how the hell can these guys say that 'generic maps' or a guy with a laptop being driven around can get the fuelling as perfect as a trained Dyno operator and a proper calibrated rolling road? The guy with the laptop can't even tell if the engine is making more power? Driving around cannot let the engine rev from idle to redline in every gear and cannot measure the load on the engine.

I'm confused, and I'm sure that I'm right in this case. If I'm wrong then why do people bother to build rolling road dynos for cars? Another few members are also arguing that you don't need to remap after modifications? I think they are crazy. Or are they?

____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

On your last point first, most cars run closed loop systems. To a large extent on anything other than very large throttle openings the car doesn't care how its fueling is mapped as it will just redo it from the feedback from the lambda probe anyway.

You can actually determine power from a laptop like that. Change in time time between sparks means you can get a pretty accurate view of acceleration, and plumb in the weight of the car and the like and you can work it out. However for mapping you want consistancy so you would need to use the same stretch of road (and really the same fuel load.

The main thing it sounds like they are mapping is the allowable boost and ignition timing rather than fuel mixture. And for this an accurate way of finding when detonation becomes a problem is needed.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

So I could increase the boost that my car produces and I would make more peak power. Simple as that? I'm really disappointed now. I know for example that the PPP ECU runs 1.2 bar max boost, and my standard ECU runs 0.9 bar boost. I've had the other PPP mods done (exhaust, centre de-cat, strengthened intercooler hose) so I could just put my boost up to 1.2bar (if I had the right software and an ODBII cable) and my car won't blow up?

I thought engine tuning was a black art, and it turns out that simply bolting stuff on can work. Sad

Damn you closed-loop fuelling systems!! Laughing

I'm still unconvinced. I'm certain a re-map will make my car faster. Maybe boost and ignition timing need to be tweaked.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

Dom_ · Points Mean Prizes Joined: 02 Aug 2004 Karma :

Simple bolt on mods only require generic maps which you can easily get hold of. So you wouldn't really need to get the car mapped and if you did it wouldn't make /that/ much difference.

"a guy with a laptop" is usually someone who knows how to map properly and has experience of it, not just some regular joe.

I don't understand mapping properly but it is a fine art, if anyone could do it then specialists would go out of business.

Live mapping (as its called) I would thought is more accurate due to it being real life situation with real loads. A few people who I know with tuned cars have all had their car tuned this way.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

With bikes you can also run into the problem that the Dyno room can act like an air box giving a huge still air supply at a higher pressure than the air inside the air box. Then when you take your bike on the road and start doing high speeds the air inside the air box ends up at a higher pressure than the air outside the bike which is moving at a relatively higher speed so the bike has trouble breathing.

The John Robinson books are good for studying this kind of stuff.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

That requires a hell of a lot of air. Unlikely any fan could manage it.

Most of the air piped to things on dynos is for cooling.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

May Veypor can calculate power/torque if you enter the weight and frontal-area.

As others have mentioned, in some ways it can be better than stuck in a dyno-room.

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

I'll give you that, it can be read both ways Wink

too used to arguing with you Razz

In my experience bikes set up on Dyno's should be taken for a test run afterwards to make sure they actually work in the real world as it's surprising how often they don't.

Bit like software I suppose, you build it in a lab then hand it over for someone to try and destroy. Trouble with Dyno's is people seem to think they can work miracles when all they are is a tool and you should always double check your work.