Ram Air and the dyno

[enginetuna]

I will have to look into this over the weekend.  The motec will have logging for everything in it providing i told it to log.  Will have a look when i have time and get back to you

[gazza414]

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.

ET, I hope your not suggesting the 2 A/F values are due to ram air?

[enginetuna]

ET, I hope your not suggesting the 2 A/F values are due to ram air?

I'm not sure what you are asking me here?
One chart is from the dyno the other from track.

[gazza414]

ET, I thought you were suggesting that at the track and at  the dyno you could compare A/F's ? even down to 3 decimal places ?

[enginetuna]

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.

I have just checked the map along with the tempertures and pressures.  They were close enough to not be corrected loads.  Both runs were at 100% throttle.  MAP was within 2kPa but that could be from the change of location.  Further detail from track below, hope its of use.

[enginetuna]

ET, I thought you were suggesting that at the track and at  the dyno you could compare A/F's ? even down to 3 decimal places ?

Not at all.  There is a discussion between the difference between dyno and track AFR.  I'm merely showing what i had on dyno one day then track the next.  Maybe my correction tables are more accurate that suzuki?  I doubt it.  Don't know.  All i'm showing here is logging at pretty close to 13k rpm from both places.  But the bike was mapped on the dyno at a set AFR with a 65mph (approx) wind then the next day its on track doing 145mph and the AFR is pretty close, like less than 0.2 difference.  Now if there was a huge amount of extra air being rammed in there it would be showing lean but its not.  I see far more of an AFR difference between a hot and cold day on the dyno.

[GenII Busa]

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.

When tuning on the dyno, make the A/F 0.3 ~ 0.5 points richer to compensate for the ram-air effect on the road.

There have been numerous discussions if the Busa actively compensates for ram-air ... the resulting answer is no.  It's most likely compensated buy the ECU knowing what gear it's in, and what the engine RPMs are ... thus, giving it a calculated bike velocity and an A/F compensation based on the bike's speed since the ram-air pressure vs. speed curve is known by Suzuki.

This also brings up another interesting issue.  If a Busa is running a TRE that simulates something besides 6th gear then the ram-air compensation is thrown off slightly because the ECU thinks the bike is going slower than it really is.

[BusaSnoop]

If this will help enyone from my peak h.p. on dyno to peak performance at the strip I had to do a lot of tuning. I ended up with 4% more fuel and advanced the timing 4 degrees. I did it in small amounts and checked my ET splits I got 2.5 tenths back that I lost after dyno

[BusaSnoop]

One more thing I forgot. The TRE I had made my bike 1 tenth slower

[PetriK]

Not at all.  There is a discussion between the difference between dyno and track AFR.  I'm merely showing what i had on dyno one day then track the next.  Maybe my correction tables are more accurate that suzuki?  I doubt it.  Don't know.  All i'm showing here is logging at pretty close to 13k rpm from both places.  But the bike was mapped on the dyno at a set AFR with a 65mph (approx) wind then the next day its on track doing 145mph and the AFR is pretty close, like less than 0.2 difference.  Now if there was a huge amount of extra air being rammed in there it would be showing lean but its not.  I see far more of an AFR difference between a hot and cold day on the dyno.

Thanks - a quick look to the pictures makes me to notice the following:
- There is 4C degree difference in intake temp
- There is 2.6kpa difference between manifold pressure (could be because of ambient pressure difference ?)
- No information about ambient pressure which is the single biggest contributing factor to AFR
- About 5 degree difference in engine temp, in busa that would not make difference in AFR - dont know about Motec
- According to the rpm behaviour it looks like the bike has been accelerating rapidly introducing accel enrichment factor in Busa, dont know how Motec owrks
- No information if Motec uses manifold pressure at the given engine conditions to adjust AFR, busa certainly does not for constant full throttle positions.
- No information about gear compensation maps of the given ecu
- Unknown battery voltage which also affects compensation
- Slow speed to see the ram air effect compared to busa top speeds. The air pressure is not linear to speed, its rather exponential.

Would not use that information provided in those pictures much for making decisions to tune my Busa for ram air. If you can find the ambient air pressure for both then could estimate the differences.

I am not trying to argue here - all written earlier in this thread is just facts based on what anyone can learn by reading the ECU and learn from that how Suzuki has designed the engine to work.

One thing though - 65mph airspeed from dyno fans, that is about 104km/h. Normally when driving that speed I usually prefer to have my visor closed as the wind resistance is high when sitting up on the bike. If that airspeed is hitting the ram air tubes and driver behind, I would need to wear goggles when dynoing the bike...

[enginetuna]

Petrik, i'm not sure you are reading the graphs properly.  The first i posted is an 8-second window of a 10-minute qualifying session.  The second is a 20-second window of an 11-minute race.  The dyno chart i posted under the first motec log is an rpm trace similar to the on track trace above just to show what AFR was in both situations.
I do not understand where you are getting a 2.6kPa manifold pressure difference from?  If you look at the 2nd picture i posted the cyan coloured line which is manifold pressure and during the 20 second window of logging i am showing the manifold pressure varies from 34.7 to 101.9kPa.  The figures you see on the right of the screen are just the figures at the point of time where the vertical blue line on the graphs is at this specific point.  The manifold pressure jumps around a lot even under constant tps conditions.
Ambient pressure is not logged here, i've just checked the logging setup.
Depending on the bike, i do have to wear goggles.  Mostly the air blows just enough under but some fairing shapes i have to pretect eyes.  The incoming air (0.5M diameter fan at very high speed) is pointed at the radiator but a portion hit the ramair intakes.
Nobody i know maps aftermarket racebike ecu's based on manifold pressure or the conditions i am showing here.  With 4 single throttle bodies there is too much pulsing going on for this to be of use.  If there was a large plenum and the pressure sensor was located in this then maybe you could go that way but that is not applicable for any bike i know of.
The acceleration on dyno is faster than on track.  I have some acceleration enrichment enabled but not for the rpm logged at the point on the graph where the black line is.
The acceleration shown is going through the gears on a straight with a quickshifter, similar to what you would see in a drag race so maybe somebody reading this may find it of some small use.
Petrik.  If you like, i can email you the motec map for this bike and the logging so that you can view all the various compensations and analyse the logging yourself.  All the data is contained in there.  You seem to be the few who understands what is happening.

[PetriK]

Havent seen any dynos so far where the fans are effective enough causing the operator to wear goggles, so that is cool  And yep - I dont really know how to read motec logs. Have only used Innovate LM1 so far... when have time could be interesting to read motec logs if the sw is avail easily.

Also I got a feeling that we are talking slightly different topics here. I am not suggesting to use manifold pressure for tuning the WOT or high power areas, this is nor the way how Suzuki has designed the ecu. Manifold pressure is only used for very small TPS positions to adjust the fuel. Well - saying that regardless of the load the manifold pressure is used to determine if PAIR should be on or off (in EU models) at full TPS range from 0-100%.

The reason why I am interested in about ambient pressure with logs that were presented: The ambient pressure is the single most important contributing external factor to the injector pulsewidht even at WOT. Without knowing how ambient pressure sensor is calibrated or mapped etc. the AFR can be anything.

For example: Busa atmospheric pressure sensor effect to the pulsewidth @ around 8000rpm, 3rd gear
3.15V = 10.2ms
3.27V= 10.8ms
3.5V = 11.5ms
The spec says that 0-600m means 3.1-3.6V sensor readings which may vary also according to the temperature. That is almost 10% of pulsewidth difference. Unfortunately I dont have a datasheet to have exact pressure readings but if that sensor is calibrated incorrectly or if there is big difference in readings it will cause big AFR differences.

In Busa the intake air difference of 4C degrees has almost no effect to the pulsewidth. Within operating range of 20-50C I can measure only < 0.01ms differences into pulsewidth @ WOT (or any other TPS position, of course I may have a problem with the test setup.).

This on the other hand puzzles me as the 4C temperature change to air density should be same as difference between 990mbar (low pressure) and 1010mbar (sunny nice day) air pressure (depending on dew point and if I got my math right, almost feels like my testing bench is not working properly) - but maybe the Suzuki engineers noticed that intake air temperature is too dependent on the engine warming the sensor up that they could only rely on external air pressure sensor ? Also the injector pulsewidht is also more dependent on coolant temperature sensor operating range values than intake air temperature sensor. (I know this because I have tested this on the desktop workbench - but like said above, I also may have something incorrect with the workbench setup. On the level I do things errors are very possible.)

And then getting back to the original discussion. The Suzuki ecu calculates the ram air pressure compensation factor based on RPM and gear. The intake air pressure sensor has nothing to do in that game. Anyhow the ram air pressure compensation factor is then multiplied by ambient air pressure factor amongst many other things. Therefore when estimating the ram air compensation correctiviness from AFR values we need always to know the ambient pressure sensor readings.

So because of the above I would not use the information provided on those images to decide on how ram air compensation works or not work.

Saying this I do not have a clue how motec works and it may be completely different ballgame with motec...

[enginetuna]

Yes my fan is pretty strong.  I can do heavy load testing on most bikes and they do not get too hot, especially this time of year.  I can have the headers glowing bright orange on a 30-second sweep test and water and oil temp are within reason.
You can download the motec ecu manager and log analysis software for free.  Motec is awesome kit.  Cost to map a superbike is about 15 times the price of a powercommander custom map but once its done you have something really special.
I will try and put an airbox pressure log on a bike this year.  Won't be a busa, maybe a gsxr600/1000 or an r6.
I don't need to bother with accurate compensation tables, as the maps get trimmed manually each session at the track if needed.
Good luck with the ecu hacking and creating new tables.  Takes me forever to get it all right and i've got a familiar and user-friendly interface.

[gazza414]

ET, if you are going to log air box pressure ..and you have a few xtra sensors can you place them in different locations ? and see if indeed there are local variations ? I had 1 in the rear of my land speed bike and I saw some wild fluctuations.

[PetriK]

Maybe this is getting a bit too techy - but there is now something I dont anymore understand. There is interest to measure the airbox internal pressure - where as I am mainly interested in about the airmass velocity through the system ? I.e. if the engine breathes better with higher gas velocity there should not necessarily be increased airbox pressure - on the other hand, there should always be higher gas velocity present ? To me Ramair is not about pressure, its about increased velocity - unless the TPS is 0%.

So far measuring the airbox pressure (for me) has not yielded useable results due to the intake pulses existing within the box causing resonanse, i.e. pressure waves going through the box. Pressure pattern inside the box (or intake manifold) has anyhow given useful information about e.g. misaligned intake cam. Also small things like just leaving out the ramair tubes during dynoing made the bike to loose 5-7hp top end outlining the importance of keeping the velocity for full ramair tube lenght.

Is there something I am missing to understand because of lack of experience and lack of repetiive logger data ?

[enginetuna]

I wouldn't look at the ramair system and tubes as a means of ramming air in but more as a way of reducing restriction and providing a clean air supply.  The size and volume of this system is very critical on the delivery.  I have done a fair bit of dyno testing with airboxes and on this one big airbox with a specific high pressure air feed sealed into it, the fiberglass airbox lid would bow outwards and then suck in a couple of times climbing through the rpm range.  I was shocked.  Opened my eyes to what goes on. 
You might also want to think of the airbox and tubes as a damper.

[entropy]

leaving out the ramair tubes during dynoing made the bike to loose 5-7hp top end outlining the importance of keeping the velocity for full ramair tube lenght.

We saw exactly this same loss with my built ZX12 on JohnnyCheese dyno a couple years ago.

pretty weird.

[GenII Busa]

You guys are making this way more complicated by trying to blow air into the ram-air ducts on the dyno to simulate ram-air pressure and trying to measure the airbox pressure.  Without ram-air, the airbox pressure will always be below ATM pressure when on the dyno.  I believe at around 60 or 70 mph on the road is when the airbox starts building pressure up over ATM pressure.  Also, the closer the pressure sensor is to the throttle body intake tubes, the more turbulent and the more pulsations there will be in that local area.

If you just add 0.5 A/F points richer at the top end without trying to simulate any road airflow, then it's going to be pretty damn close when on the road.

[Busa Quick]

You guys are making this way more complicated by trying to blow air into the ram-air ducts on the dyno to simulate ram-air pressure and trying to measure the airbox pressure.  Without ram-air, the airbox pressure will always be below ATM pressure when on the dyno.  I believe at around 60 or 70 mph on the road is when the airbox starts building pressure up over ATM pressure.  Also, the closer the pressure sensor is to the throttle body intake tubes, the more turbulent and the more pulsations there will be in that local area.

If you just add 0.5 A/F points richer at the top end without trying to simulate any road airflow, then it's going to be pretty damn close when on the road.

 It would be nice to see the charts or info that makes your decision of .5 A/F the right one. I am not arguing with you but, the conversation is how to get exact numbers using recorded data.

Mark

[quizesilver]

so for dyno run
we juz need to tune it to abt 0.2 to 0.3 richer then std?
for all gear ?

[GenII Busa]

You guys are making this way more complicated by trying to blow air into the ram-air ducts on the dyno to simulate ram-air pressure and trying to measure the airbox pressure.  Without ram-air, the airbox pressure will always be below ATM pressure when on the dyno.  I believe at around 60 or 70 mph on the road is when the airbox starts building pressure up over ATM pressure.  Also, the closer the pressure sensor is to the throttle body intake tubes, the more turbulent and the more pulsations there will be in that local area.

If you just add 0.5 A/F points richer at the top end without trying to simulate any road airflow, then it's going to be pretty damn close when on the road.

 It would be nice to see the charts or info that makes your decision of .5 A/F the right one. I am not arguing with you but, the conversation is how to get exact numbers using recorded data.

Mark

The best way to get exact number with recorded data is to put an on-board wide band O2 sensor and data logger on the bike and go tune it on the road.  Of course, that's too expensive and complicated for most.  The 0.5 A/F richer on the dyno was verified by Motorhead many moons ago.  If someone with an on-board O2 data logger tuned the bike on the road to be perfect and then ran it on the dyno with zero ram-air, then it's going to be slightly richer on the top end when on the dyno.

Besides, IMO 0.5 A/F off at near redline in 6th gear probably isn't going to be noticeable except for guys strictly running for top end speed contests.

[GenII Busa]

so for dyno run
we juz need to tune it to abt 0.2 to 0.3 richer then std?
for all gear ?

I believe that is for 6th gear -- but it's more like 0.3 to 0.5 richer A/F.  If you use lower gears then it won't be quite that much.  In 6th gear is when the ECU is compensating for the ram-air the most since at X RPM in 6th gear makes the bike go faster than say X RPM in 4th gear.  The faster the bike is going, the higher the ram-air pressure and the more fuel compensating there is.