Ram Air and the dyno

[BusaSnoop]

How is ram air compensated for when dyno tuning. I had my bike dynoed took fuel and timing away made good power went to the track and it ran terrable. End result put fuel and timing back at it gained 2 tenths back in an hour of testing. Has anyone ran in to this and is their a standard amount that needs to be added back after dynoing.

[KSpecII]

ram air is not compensated on the dyno if the tuner follows the std a/f... so i guess you may be running lean when the ram air effect kicks in...

[entropy]

Does the Busa have an air pressure sensor monitoring the airbox/TB's?????

If so, wouldn't the ECU compensate for any ram air increases???

[KSpecII]

there's an IAP sensor.. but the ram air effect is normally not in full force due to the poor sealing of the air box to the ram air tubes...

the issue would then be when the ecu compensates for the air pressure, will it be sufficient given the different "breathing" patterns of the modded bike..

[Pete]

Does the Busa have an air pressure sensor monitoring the airbox/TB's?????

If so, wouldn't the ECU compensate for any ram air increases???

Yes but it only compensates for vacuum, not positive-pressure.

[whtrthanu]

when I tune on my dyno, and im sure that other shops that are experienced do, you do not have the best or peak hp numbers after you tune for track simulation....
i used a data logger on a test bike and went from the dyno to the track, and you be suprised how off the tune up is at high speed from the dyno...

[glenn71]

I,ve read each gear has differnt enrichments to allow for ram air..2 for 3rd,.3 for 4th,.4 for 5th,.5 for 6th.As my busa seems to make the most power (ON THE DYNO) around 13.6-7 and the bike is tuned in 4th gear on a dj250i my tuner maps it to 13.2 in that gear.Now if suzuki equated .3 for that gear enrichment the assumption is it,ll end up around 13.5 on the road.Interestingly those that have the gps mod and yosh tune their bikes may discover the .4 enrichment now applies to all gears making 1st and 2nd a bit rich and one guy i know struggled to lean it out on idle because of this.

[entropy]

Does the Busa have an air pressure sensor monitoring the airbox/TB's?????

If so, wouldn't the ECU compensate for any ram air increases???

Yes but it only compensates for vacuum, not positive-pressure.

please explain, i don't understand.

Also, where in the intake track is the Busa sensor? 

In the ZX12 the MAP sensor takes its feed from the TB, and the pressure is always less than ambient on the dyno.

However, at 190mph the ram air gets it up to ambient, just.

[enginetuna]

I generally find that on my superbike customers we will find on average it runs about 0.2 AF leaner on track than how i setup on dyno.  So 13.2 becomes 13.4 on track.  Fan air speed on my dyno is around 60-70mph.  But then these guys rarely go over about 150mph and that is only for a very short time.
One thing you will also find on some of the suzuki ecu's is the fuelling changes depending on how fast the engine accelerates.  I was testing a k6 1000 last week and found that 4th and 5th gear roll-on fuelled differently, as did sweep testing for the same gear and then step testing again was very different.  They do weird things with the timing and upper butterflies depending on load and rpm rate.  And upper/lower injector duty also changed.

[Pete]

Does the Busa have an air pressure sensor monitoring the airbox/TB's?????

If so, wouldn't the ECU compensate for any ram air increases???

Yes but it only compensates for vacuum, not positive-pressure.

please explain, i don't understand.

Also, where in the intake track is the Busa sensor? 

In the ZX12 the MAP sensor takes its feed from the TB, and the pressure is always less than ambient on the dyno.

However, at 190mph the ram air gets it up to ambient, just.

The anual says the sensor only compensates for vacuum, it's branched off all 4 tb's.

[gazza414]

Read also PetriK's thread 

also without a wideband its in open loop and the percentages are SFA

you can do the calcs or data log the airbox pressure..ya gotta be going fast for any "BOOST" influence

[PetriK]

Yep - as far as I have tested the IAP sensor does not adjust for anything at WOT (wide open throttle, well turns the fuel off if enginge stalls etc. but under normal running conditions).

There is an acceleration enrichment there, but that is related to the TPS change e.g. when doing a normal cluched gear change or trying to shoot for the best 60ft time. I am particularly intrested to tweak the accel enrichment (together with ignition) for first 60ft...

The key point is that there may be 3% difference between gear 1 low load and gear6 full load settings. With guys running TRE you can only have either rich streetbike or lean speedbike. This is one of the reasons why I am so keen on tuning the ECU directly to remove the 6th gear rpm limiters. If you dyno in static air (blowers do not really generate any ram air effect) you should dyno for a tad bit rich. Who cares if the mapping is done to +-1% if in real word its gonna be off for 3% at LSR events.

Below you can see the ram air compensation maps for 1st gear, 6th gear low load and 6th gear full load situations. Below that you can see the changes in terms of injector pulsewidth between gear 1 and gear 6 at 10.000rpm @ full throttle. This something to bear in mind when comparing air pressure when running 200mph vs. fans at dyno. It comes to around 3% which ever way you calculate it.






Anyhow its possible that Suzuki is fooling us and running the engines a bit rich at those speeds just to protect the engine so we dont know if those numbers are truly real. Only the guys who have been running WBO at LSR can give an exact answer to that. I would not trust the intake pressure sensor for that information as that affects not only the pressure but also propably the pulse tuning of intake and through that to the VE of the engine for any given speed. So only WBO can give an exact answer.

[entropy]

Petrik,
GREAT investigation!

If i understand you the Intake Air Pressure has no impact when in 6th gear.

Is the Intake air Pressure the same as the Manifold Air Pressure mentioned above?

 Does the Busa also have an atmospheric air pressure sensor.

On the ZX12, I was under the impression that the ECU took the differential between the MAP sensor (TB's), and the atmospheric pressure sensor (in the tail) and somehow computed changes to fuel.  Is this not true?

I am a bit confused
(not an unusual state)

[PetriK]

You are absolutely correct about ecu using the diffence between IAP (intake air pressure, ie. manifold pressure) and ambient pressure.

Anyhow for fuel calculations the IAP is not taken into account after appr 10% throttle opening (appr 28% voltage). Instead the ambient pressure affects also the TPS maps so by modifying the ambient sensor (with an additional resistor) you can fool your ecu to run higher rpms before getting FI light (in theory) and only after remapping all the fuelmaps (or getting the DaveO extended ecu mod).

[gazza414]

The fuel maps will need to be remapped as you prob know Karl as Dave O's and others  mod is simply to change the clock speed.

[BusaSnoop]

So to put all this in to terms most peaple can understand. If your tuning for peak H.P. on the dyno you will need to add 2-4% full throttle fuel at the strip\street to get the tune up right.  Thanks for the info to all.

[entropy]

The fuel maps will need to be remapped as you prob know Karl as Dave O's and others  mod is simply to change the clock speed.

gazza,
yep, i have a DaveO modded ECU, it works great, and as you poing out it needed just a titsch more fuel to accommodate the increased clock speed.

Also, i send it back back to DaveO each Spring and Fall to have the clock adjusted for Daylight Saving Time...

[gazza414]

The fuel maps will need to be remapped as you prob know Karl as Dave O's and others  mod is simply to change the clock speed.

gazza,
yep, i have a DaveO modded ECU, it works great, and as you poing out it needed just a titsch more fuel to accommodate the increased clock speed.

Also, i send it back back to DaveO each Spring and Fall to have the clock adjusted for Daylight Saving Time...

and here I'm thinking you guys dont have a sense of humour!!!!

Dave struggled with my clock speed ...14 hrs ahead here mate...my ECU runs in a cryo bath

all the best anyway Karl with that Kawa and hope ya break some records..head down , ass up seems to work at speed

[enginetuna]

So to put all this in to terms most peaple can understand. If your tuning for peak H.P. on the dyno you will need to add 2-4% full throttle fuel at the strip\street to get the tune up right.  Thanks for the info to all.

I would say at most 2% unless you are running way past 160mph

[Rollin99]

when I tune on my dyno, and im sure that other shops that are experienced do, you do not have the best or peak hp numbers after you tune for track simulation....
i used a data logger on a test bike and went from the dyno to the track, and you be suprised how off the tune up is at high speed from the dyno...

a good tuner will do this everytime if a customer is a track guy...you gotta know usage of the bike to give the customer the best tune...

[glenn71]

when you say 2% more fuel how does that equate to air fuel.is that like .2-.3 air fuel.I doubt it  as i saw that much change with directed fans on a dyno.I would have thought up to 1.0 change at approx 150mph?A wideband can log a map signal and i wish to do this at the drags this year with differnt air box ideas.people say theres barely any boost until 150mph.Have they compared airbox negative pressure on a dyno to pressure at speed.Less negative pressure is still better albeit not yet positive.

[PetriK]

That 2-3% number came directly from comparing injector pulsewidth with top speed on 6th gear (over 300km/h) and cruising speed from ECU factory settings. The point here is that usually when dynoed with TRE you only use one gearmap and compensate for static ramairpressure which does not reflect the real world conditions. The ramair pressure changes by speed that is within ecu calculated based on RPM. The powercommander map is based on RPM. So when dynoed and tuned against static airpressure you actually kind of reprogram you bike to remove the ramair compensation. The net result you can see from the powercommander maps - often with mildly modified bikes at dyno you take fuel off from high rpm to have optimum power under static ramair pressure...

For dyno you really should program the ecu for a flat 5th gear RAM air compensation map which equals the airpressure from cooling fans in to the ECU and then dyno the bike. Then after dyno you should reprogram the 5th gear compensation map back to original. With this method your fuelmap is not compensated against the 5th gear ram air compensation map and in real world driving conditions your afr ratios will be closer to the optimum. (This assuming that you dyno on the 5th gear). Alternatively of course a datalogger and real world situations will be the way to do it, especially as you one finetune the gearspecific ram air compensation maps by programming the ecu for optimum afr. Which ever way, having the TRE connected will mess the afr when speed increases. Well - in truth we are talking here only a couple of ponies, TRE is messing up the way how Suzuki designed fuel maps: to be as perfect as possible.

There is no need anymore to have TRE on the bike that in practise removes the ram air compensation. The top 6th gear speed limiter can be removed by reprogramming the ecu which allows the ram air compensation to work correctly. .... well the above really applies only to NA engines ... with nitrous and turbos the fuel requirement is dependent on other things. But also with turbo and nitrous reprogramming the ecu to remove the top speed limiter and raising the rpm limiters has its benefits. For nitrous I really like the ecu feature to reprogram the intake flap solenoid control to act as a nitrous window control switch.

But this is of course personal view from only... and I am not a bike tuner with LSR records.

ps. The dyno fan  may not be directed directly to the nose causing maximum pressure in the intake, usually they are directed towards the radiator for maximum cooling.

[enginetuna]

when you say 2% more fuel how does that equate to air fuel.is that like .2-.3 air fuel.I doubt it  as i saw that much change with directed fans on a dyno.I would have thought up to 1.0 change at approx 150mph?A wideband can log a map signal and i wish to do this at the drags this year with differnt air box ideas.people say theres barely any boost until 150mph.Have they compared airbox negative pressure on a dyno to pressure at speed.Less negative pressure is still better albeit not yet positive.

Here is dyno AFR (lower graph) and Motec lambda logging (upper graph) from the following day.  The logging is in 6th gear on a gsxr and the dyno run in 5th.  Looking at the 2 graphs, dyno lambda is 12.68 and track lambda for same rpm at 145mph is 12.797
My dyno fan is pushing around a 65mph air at the front of the bike so the ramair system is seeing a bit of this.

[glenn71]

great stuff.

[PetriK]

Here is dyno AFR (lower graph) and Motec lambda logging (upper graph) from the following day.  The logging is in 6th gear on a gsxr and the dyno run in 5th.  Looking at the 2 graphs, dyno lambda is 12.68 and track lambda for same rpm at 145mph is 12.797

Excellent - do you have the intake air temperature, ambient pressure and TPS sensor readings for these two different measurements ? Fuel injector pulse is highly dependent on ambient pressure as it is calculating the pulsewidth by based on difference between ambient and intake air pressure.