[jmmmrm]

OK. I finally got my bike up and running and recently got it dyno'd in. However, I am having a problem and need some help.



My bike is a 1995 900ss, converted to FI (1999 900ss ecu), 3 mm bore, 2mm stroke, ST2 cams at 108 lobe centers, Guy Martin full heads, open airbox, power commander. The first dyno is from when I first got it converted to FI with the ST2 cams and power commander. No head work and stock ECU. As you can see, it pulls to 8300 rpm with a hp of 92.4.

The second dyno is with Guy's heads and a remapped ECU. Run 008 is a full d&d 2 into 2 with no cross over and dyno 015 is with a spaghetti header and termi slip ons. It stops dropping power after 7800 rpm.

Why the drop? I am assuming that it has something to due to the flashed ECU. Sugestions? Also, anyone have a spare ecu (the sandwich type) that I can borrow/buy to narrow this issue down?



Thanks



Mike

 

[robnobrakes]

Different dyno and operator, different weather conditions.

By the way; fuel air ratio of 17.5 is way too lean.

 

[jmmmrm]

No. Different dyno and humidity etc might affect total HP/Torque, but it would not affect the line dropping off at 7800 rpm.

 

[jack]

So, how does it run on the street or track? Dynos are great but no body rides on a dyno ....

Personally, I would be thrilled with it. You got nearly 100 hp and huge mid range power without having wring it out. Shift early!

 

[944SS]

Congrats on getting your project together and 98.8HP on a 2V is a good problem to have!

Your challenge is that you changed a few variables at the same time: heads, 95mm bore and re-map. I was surprised the red heads didn't get you more top end as well since removing restrictions to flow at higher rpms is what they are all about. They certainly added a nice gain up to 7800 rpm though.

I guess I'm with you on the re-map being your prime suspect. Any chance the stock injectors hit the upper end of their duty cycle with this kind of power? I've run into that in the automotive world. Interesting the D&D with no crossover delivers a much nicer power curve and better torque. Mind you, that may disappear as you re-map and tune.

 

[1fast750ss]

Frankly, I'm not seeing any problems with the curve. It is a very typical power curve for a big bore, fuel Inj, 2 valve motor. Much nicer as it seems to have some nice work done to it. Typical VE falloff for the 2V motor, even with the mods you have.

Shift in the 7500-8000rpm range. She'll be a beast.

If you want to tinker some more, look into cam timing with the ST2 cams. You can probably play a bit with them, but you may have to compensate with less ignition up top. If you can flash your ECU, no big, but save the map you have. As mentioned earlier, the A/F seems a bit lean.

 

[jcns]

What was your A/F ration on the 2nd run? If it's lean, it may explain the drop after 8K rpm. It's possible that the injectors are maxed.
You can shift at 8k rpm and consider the rest of the rev range as "overrev". or tune it to shift the power curve to the top end.

 

[1fast750ss]

OK, I see the second dyno pulls(I'm not sure why it didn't come up the first time. I see what you are saying. The A/F looks good, but you are having falloff similar to a carby SS, with longer inlet manifolds.

The ST2 cam characteristics aren't showing here either. It looks more like a modded carby SS with stock cams or DP cams(the exhaust duration is only 230). You should see a flatter topend rather than the falloff. You may want to check your cams, by measuring your exhaust lift and duration(at 1mm), unless you are positive they are ST2 cams. If so, it would be a case of cam timing more than anything else here.

 

[Punch]

AFR, cams and mapping

I am in the process of remapping etc. and no expert, but have learnt quite a lot on the way.
As 944SS wrote, you have changed more than one thing, so that makes it difficult to pinpoint the cause.

Our 2V engines "like" an AFR of around 12.5 The lowest chart shows AFRs near this, but the higher chart shows higher AFRs. I would be having a very close look at that for a start. Typically a 4% change in fuel (injector duration) will change AFR by one whole point. If the PC allows it, maybe try a "global" plus 4% to see what your butt dyno senses. Plugs will also tell you a bit - check the NGK web site for reading plugs. Do you have a wideband oxygen sensor in the bike? I use the Innovate Motorsports LC-1 and comparing it to the dyno O2 sensor it is very accurate, but AFR will lag reality by about 500 rpm, but it will allow you to do some on road observation. It also comes with logging software, so if you have a laptop, you can strap it to the pillion seat and log. If you are scientific about it you can get a lot of info but planning the runs/logs. E.g. do a number of rides starting from different throttle positions and hence position in the map to see what AFRs you are getting.

Cam timing (my current project) is very important. Check bikeboy.org for dyno results in the Duc 2V section. Also check this excellent thread for details. http://www.ducati.ms/forums/showthread.php?t=57362&highlight=750+exhaust

Your map will now not be best to get maximum benefit from all the changes, so you have something to look forward to!. I am working with TuneBoy, who are only 45 minutes from me, to remap my EFI. Really good results, but it highlighted a mistake I made in making the exhausts restricted - I have had new pipes made and after cam timing will go back to TB to finalise the map. Also look at the TB website for comparisons to PC.
Have you enlarged the crossover yet?
Changing pipe length, diameter etc. can have a big impact on performance. Just Google exhaust tuning to read about pressure waves etc.

When doing dyno runs and mapping a number of runs should be made from a variety of starting throttle positions to "position" the bike in a number of spots in the map to then establish what has to be tweaked.
Ignition advance may well be out, particularly at high revs. TB found the DP ECU (Marelli 15M) to be mostly OK, but better at bit more advance at high revs. Here we did a few runs changing advance, then selected the least advance for the range of advances we tried when power remained the same.

I will watch with interest!

 

[jmmmrm]

Thanks for replies. I am happy with the set up and it runs great, BUT, since I spent the money on the heads, I might as well get the most of it.

The cams were set at a 108 degrees so the timing of them is not the problem.

The fuel injectors theory is an interesting one which I will look into, but my initall thought is that the powercommander should take care of any fuel issues. Not to mention the A/F ratio is still good until the end.

The exhaust issue I think is a mute point. The d&d's are larger than stock and I still get a drop off. I was surprised though that they gave more torque (though the humidity was lower) and got more hp quicker.

I intend to do the following and see if I can narrow it down.

1) Remove air box and see if that helps.

2) Try to get a stock ecu and run it again and see if they messed up on the flashing of mine. I know that they retarded the ignition, but as to how much I do not know yet.

If neither of these work, I will have to remove one of the cams and make sure that they are still st2 cams. Mistakes happen and perhaps they got mixed up (I don't think so though). And yes, they were definately ST2 cams as I took them out of an st2 myself.

Will keep you posted.

Mike

 

[Pablo Pirate]

Nice one JMMMRM!!! Impressive

Cheers Pablo

 

[Punch]

Various to your post

Cams 108 agrees with a few tuning sources.

Fuel injectors maxing out - I doubt that they have met maximum duration. 900SSie uses greentop Webers and I understand that 99X also do so, so they should not have met maximum "on time". "PC dealing with fuel issues" - in general these things only do what you tell them, unless like MyEcu, there is the option for closed loop operation, requiring a wideband O2 sensor installed. I.e. if it is not matched/setup for your mods, then it is pure guesswork.

Removing the airbox should if anything only lean off the AFR, not richen it which is what I think is needed from the charts shown. I tested AFR with a K&N and open airbox lid to no filter or lid at all. Not noticeable change in AFR, so well done K&N - excellent airflow.

Stock ECU - I seriously doubt if this will show anything as it will be well away from the correct map for all your mods, so could be equally as good or bad as whatever your ECU and PC combination is doing to the map.

Putting on my science hat for a moment, if it was my bike, I would start the experiments now by changing one thing at a time, keeping records, then tweaking based upon data.

Richard

 

[jmmmrm]

Well, just got my bike back today. I removed the airbox and installed some pod filters. Here is the result.

It does help out on the top end but I am still getting a steep drop after 8200 rpm. I was also told that I am getting detonation b/w 4500-5500 and on the top end. I guess I will have to have the ECU reflashed after all.



I think it is interesting however that b/w 0-6600 rpm there is no difference b/w an open airbox and the pod filters.



Anyway, broke the 100 mark with 103.

 

[ENGAKATS]

Great results so far from a 900FI engine!!

In your last graph there's an improvement on the top end but the rest of the graph hasn't realy changed. If I were you I'd work on Run_008 with the fatter mid-range and try to improve its top end :think:

...I was also told that I am getting detonation b/w 4500-5500 and on the top end...

Why do they say that? Can they hear it or what?

 

[jmmmrm]

I did not get into the specifics in great detail as to whether he heard or felt the detonation, but he definately assured me that it was happening.

Run 008 is kind of interesting b/c there is no crossover with the D&D system. However, I think I will wait on the exhaust tweaking until everything else is gone through (BTW, Punch makes an interesting comment about increasing the crossover).

I will be taking it to Doug in MN to get it on his dyno in the next couple of weeks to remap the ignition and make sure that that part of the equation is taken care of. Last thing I need is for a ring valley to collapse on me again due to detonation.

Will keep you posted.

Mike

 

[jmmmrm]

For those of you that care. Got my bike back today.

Changes that were made were:

1) Switched from DPR9EA to DR9EA plugs
2) Stock manifolds
3) Cams at 112.5

It no longer has any detonation problems and the curve is looking more in line with what I initially expected. So, no more tinkering until winter.

 

[944SS]

Comfortably over the ton....Fantastic result Mike! Love to hear your ride impressions, that thing's gotta be a beast.

 

[joepopp]

That kicks butt! Nice work.

 

[lechef]

Great results!

Strange with the no crossover exhaust making so much torque since the spagetti style headers is known for torque.

What exhaust where you using and what diameter where they.

Please spec both exhausts.

 

[pegaxs]

http://www.metacafe.com/watch/1813437/exhaust_systems_and_performance_2_into_1_vs_2_into_2/

Watch this video... I know its about Harleys and i know its about exhausts, but there is about 80% of the video explainging good and bad dyno graphs. starts at about the 3:30 mark... the interesting talk about what is happening to your bike starts about the 6:10 mark. Talks about peak numbers. Looks good at 105HP but your torque never increases. And probably why your first dyno graph was probably the best one of the lot.

I cant be bothered typing out 14 pages of what is good and what isnt, this video does a great job of explaining why a bike with 10hp less will probably pull past you.

So for everyone saying "well done on the HP man!!" i wouldnt just yet. He is losing torque somewhere. While the peak HP is up there, the torque has gone way down. From almost 80ft-lbs to just on 70ft-lbs and keeps losing it after about 7000rpm. Unfortunately the 1st dyno graph does not show any torque curve. Bike looks like its losing its "volumetric efficiency" somewhere... I would look at your exhaust system. Changing the filters just allowed it to get more air in quicker, but in doing that, it seems its escaping to fast ?

Part 2 of the video above is.. You should watch both... It's all about "2 into 2" and "2 into 1" exhausts.

http://www.metacafe.com/watch/1813484/exhaust_systems_and_performance_part_two/

http://en.wikipedia.org/wiki/Volumetric_efficiency

And one last quote i found was...

Real-world power is about area under the curve, not peak values. Dyno testing can give you peak values and may give you a graphical idea of the area under the curve, nothing beats a full-throttle blast down the track for measuring as-delivered power.

Or my other favorite...

Fully warmed-up dyno numbers will not impress people with how big your pee pee is. But they will allow you to accurately test the effectiveness of your HP mods.